Liquid heating pump for conveying and heating liquid in a water-bearing domestic appliance

Abstract

A liquid heating pump includes an impeller chamber having an impeller, which can be rotatably driven, and a diffusor chamber and/or pressure chamber arranged axially downstream in the flow direction and having a stationary diffusor. A heating device is associated with the diffusor and/or pressure chamber. The diffusor has a main body, in particular in the shape of a circular cylinder. The main body has a front wall on which a guide blade portion is arranged which axially protrudes in a direction of the impeller into a liquid ejection region of the impeller arranged around an outer periphery of the impeller and which extends away from the liquid ejection region outwardly toward an axial outer casing of the main body, which axial outer casing is arranged radially further outwardly than the liquid ejection region of the impeller.

Claims

1. A liquid heating pump for conveying and heating liquid in a household appliance which uses water, the liquid heating pump being at least one of a household dishwasher heating pump or a washing machine heating pump, said liquid heating pump comprising: a housing having a centrally arranged suction channel for suctioning the liquid in an axial suction direction, an impeller chamber arranged axially downstream of the suction channel and receiving suctioned liquid, and a diffusor and/or pressure chamber which is arranged axially downstream of the impeller chamber, viewed counter to the suction direction, and which is arranged externally, coaxially, at least around a partial portion of the suction channel; an impeller rotatably mounted in the impeller chamber for conveying the liquid into the diffusor and/or pressure chamber; a stationary diffusor in the diffusor and/or pressure chamber, said stationary diffusor comprising a main body having a front wall in facing relation to the impeller chamber to form a front defining wall of the impeller chamber, said main body of the stationary diffusor including on the front wall at least one guide blade portion which axially protrudes in a direction of the impeller into a liquid ejection region of the impeller arranged around an outer periphery of the impeller, said at least one guide blade portion extending away from the liquid ejection region, positioned obliquely deviating from a radial direction in the impeller direction, toward an axial outer casing of the main body as far as the axial outer casing of the main body, which is arranged further radially outwardly than the liquid ejection region of the impeller; a heating device operably connected to the diffusor and/or pressure chamber for heating the liquid, said heating device comprising at least one axially extending, partial portion of an external defining wall of the diffusor and/or pressure chamber, with the axial outer casing of the main body of the stationary diffusor forming at least one axially extending, partial portion of an internal defining wall of the diffusor and/or pressure chamber; and a discharge port for ejecting the liquid.

2. The liquid heating pump of claim 1, wherein the main body of the diffusor has the shape of a circular cylinder, said axial outer casing being defined by a diameter which is selected to be at least equal to 80% of an external diameter of the diffusor and/or pressure chamber.

3. The liquid heating pump of claim 1, wherein the impeller has an external diameter which is selected to be between 40% and 80% of the diameter of the axial outer casing of the main body of the stationary diffusor.

4. The liquid heating pump of claim 1, wherein the heating device, on the partial portion formed thereby or an entire portion formed thereby of the external defining wall of the diffusor and/or pressure chamber, provides an electrical surface heating load of between 30 W/cm.sup.2 and 50 W/cm.sup.2, said diffusor and/or pressure chamber having a cross section in a shape of an annular gap to define a cross-sectional passage surface area for heat dissipation of the electrical surface heating load, said cross-sectional passage surface area being selected to be between 8 cm.sup.2 and 20 cm.sup.2.

5. The liquid heating pump of claim 4, wherein the at least one guide blade portion is integrally formed on the front wall of the main body of the stationary diffusor, such that the at least one guide blade portion assumes an oblique position relative to the radial direction of the impeller in a rotational direction thereof, when viewed from a radially inwardly located initial portion to a radially outwardly located end of the at least one guide blade portion.

6. The liquid heating pump of claim 5, wherein the at least one axially protruding guide blade portion extends outwardly with the radially inwardly located initial portion tangentially away from an internal peripheral point on a circle of the liquid ejection region of the impeller, said radially outwardly located end portion opening tangentially on an outer peripheral point on an outer peripheral circle of the axial outer casing of the main body which outer peripheral point is different from the internal peripheral point.

7. The liquid heating pump of claim 4, wherein the at least one guide blade portion has a direction of curvature in a rotational direction of the impeller on the front wall of the main body of the stationary diffusor.

8. The liquid heating pump of claim 4, wherein the at least one guide blade portion extends in the form of an outwardly opening arcuate portion.

9. The liquid heating pump of claim 4, wherein the main body includes three of said at least one guide blade portion which are integrally formed on the front wall of the main body of the stationary diffusor facing the impeller chamber, such as to extend, when viewed from their radially inwardly located initial portion to their radially outwardly located end, in a peripheral direction over an angular range of between 45° and 90°, respectively, and thereby respectively cover in a plane spanned by the front wall of the main body a radial distance, which is located between the liquid ejection region of the impeller and the axial outer casing of the base body.

10. The liquid heating pump of claim 9, wherein the radial distance is between 5 mm and 10 mm.

11. The liquid heating pump of claim 4, wherein the main body includes a plurality of said axially protruding guide blade portion arranged in offset relation by approximately a same centering angle, such as to establish between two adjacent ones of the axially protruding guide blade portions, viewed in a peripheral direction, a liquid guide channel leading outwardly to the axial outer casing of the main body.

12. The liquid heating pump of claim 4, wherein the axially protruding guide blade portion has at least an initial portion, along an entire extent thereof, to cover from outside the liquid ejection region of the impeller on the outer periphery, across an axial width thereof with a remaining radial gap.

13. The liquid heating pump of claim 12, wherein the remaining radial gap is selected in a region of the initial portion to be between 0.5 mm and 2 mm.

14. The liquid heating pump of claim 4, wherein the impeller includes a blade which has an oblique position relative to the radial direction of the impeller counter to a rotational direction of the impeller.

15. The liquid heating pump of claim 14, wherein an acute intermediate angle of at most 50° is enclosed between an imaginary, tangential, extension of a radial outer end portion of the blade of the impeller and an imaginary, tangential, extension of the initial portion of the at least one guide blade portion protruding from the front wall of the main body facing the impeller chamber in an axial direction.

16. The liquid heating pump of claim 14, wherein the guide blade portion has a radially inwardly located initial portion which has a contour which is different from a contour of an end of the blade of the impeller on an outlet side.

17. The liquid heating pump of claim 4, wherein the axial outer casing of the main body of the stationary diffusor includes at least one radially protruding guide blade portion.

18. The liquid heating pump of claim 17, wherein the radially protruding guide blade portion extends in the form of a helical portion outwardly on the cylindrical main body.

19. The liquid heating pump of claim 17, wherein, when viewing in the direction of a front wall of the main body facing the impeller chamber, the radially protruding guide blade portion extends on the axial outer casing of the main body of the stationary diffusor at least in an outer peripheral region of the main body which is located between a radially outwardly arranged end of a first one of the at least one axially protruding guide blade portion and a radially inwardly arranged initial portion of a second one of the at least one axially protruding guide blade portion arranged downstream, when viewed in a rotational direction of the impeller.

20. The liquid heating pump of claim 17, further comprising an outlet, for an end portion without guide blades of the axial outer casing, between a downstream end of a first one of the at least one radially protruding guide blade portion radially protruding on an axial outer casing side, and an upstream end of a second downstream one of the at least one radially protruding guide blade portion radially protruding on the axial outer casing side, viewed in a rotational direction of the impeller, wherein in an installed position of the stationary diffusor the outlet is arranged in an upper region of the main body, approximately in the 12 o'clock position thereof.

21. The liquid heating pump of claim 17, wherein the at least one axially protruding guide blade portion is continuously connected, via a connecting portion integrally formed thereon, to a downstream one of the at least one radially protruding guide blade portion assigned thereto on an axial outer casing side, viewed in a rotational direction of the impeller, to form a combined guide blade.

22. The liquid heating pump of claim 21, wherein the connecting portion extends along an outer peripheral portion of the front wall of the main body facing the impeller chamber.

23. The liquid heating pump of claim 21, wherein the connecting portion comprises an axially protruding, circular arc projecting portion, and a projecting portion protruding radially in a helical manner, on an axial front face of the axially protruding, circular arc projecting portion.

24. The liquid heating pump of claim 23, wherein the axially protruding, circular arc projecting portion has an axial extent which reduces continuously from an initial portion connected to the at least one axially protruding guide blade portion as far as an end connected to the at least one radially protruding guide blade portion on the axial outer casing side.

25. The liquid heating pump of claim 21, wherein, when viewed on a front wall of the main body facing the impeller chamber, the at least one guide blade portion radially protruding on the axial outer casing of the main body of the stationary diffusor and an upstream extension formed by the radially protruding projecting portion of the connecting portion extends in an outer peripheral region of the main body in a gap between a radial outer end of a first one of the at least one axially protruding guide blade portion and a radial outer end of a second adjacent one of the at least one axially protruding guide blade portion, viewed in the rotational direction of the impeller.

26. The liquid heating pump of claim 21, wherein, viewed in an installed position of the diffusor, the at least one axially protruding guide blade portion and the connecting portion to the at least one radially protruding guide blade portion assigned thereto on the axial outer casing side, are arranged in an upper region of the front wall of the main body facing the impeller chamber such that an air bubble which may be present above the main body in the diffusor and/or pressure chamber is prevented from flowing back inwardly in a direction of a center of the impeller chamber in a rotational operation of the impeller.

27. The liquid heating pump of claim 17, wherein the at least one guide blade portion axially protruding on the front wall of the main body facing the impeller chamber, terminates on an outer periphery of the main body, in a peripheral position in which an upstream one of the at least one radially protruding guide blade portion on an axial outer casing side, viewed in the rotational direction of the impeller, terminates on the axial outer casing of the main body, viewed downstream, with an axial spacing from the front wall of the main body of the stationary diffusor facing the impeller chamber.

28. The liquid heating pump of claim 1, wherein the front wall of the main body of the diffusor has a radial outer edge zone which is configured to transition into an axial longitudinal extent of the axial outer casing of the main body in the form of a rounded portion.

29. The liquid heating pump of claim 1, wherein the heating device has an initial portion which viewed in an axial outflow direction counter to the axial suction direction is arranged in the impeller chamber.

30. A household appliance which uses water, the household appliance being at least one of a household dishwasher or a household washing machine, comprising a liquid heating pump, said liquid heating pump comprising a housing having a centrally arranged suction channel for suctioning the liquid in an axial suction direction, an impeller chamber arranged axially downstream of the suction channel and receiving suctioned liquid, and a diffusor and/or pressure chamber which is arranged axially downstream of the impeller chamber, viewed counter to the suction direction, and which is arranged externally, coaxially, at least around a partial portion of the suction channel, an impeller rotatably mounted in the impeller chamber for conveying the liquid into the diffusor and/or pressure chamber, a stationary diffusor in the diffusor and/or pressure chamber, said stationary diffusor comprising a main body having a front wall in facing relation to the impeller chamber to form a front defining wall of the impeller chamber, said main body of the stationary diffusor including on the front wall at least one guide blade portion which axially protrudes in a direction of the impeller into a liquid ejection region of the impeller arranged around an outer periphery of the impeller, said at least one guide blade portion extending away from the liquid ejection region, positioned obliquely deviating from a radial direction in the impeller direction, toward an axial outer casing of the main body as far as the axial outer casing of the main body, which is arranged further radially outwardly than the liquid ejection region of the impeller, a heating device operably connected to the diffusor and/or pressure chamber for heating the liquid, said heating device comprising at least one axially extending, partial portion of an external defining wall of the diffusor and/or pressure chamber, with the axial outer casing of the main body of the stationary diffusor forming at least one axially extending, partial portion of an internal defining wall of the diffusor and/or pressure chamber, and a discharge port for ejecting the liquid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention and its advantageous embodiments and developments and the advantages thereof are described hereinafter in more detail with reference to drawings showing exemplary embodiments. In each case, in a schematic sketch:

(2) FIG. 1 shows in a schematic view a household dishwasher with an advantageous variant of a liquid heating pump configured according to the invention,

(3) FIG. 2 shows in a schematic longitudinal sectional view the liquid heating pump of FIG. 1,

(4) FIG. 3 shows schematically in longitudinal section the diffusor of the liquid heating pump of FIG. 2,

(5) FIG. 4 shows schematically in a perspective view the liquid heating pump of FIG. 2 in the open state in which its first housing part with the drive unit contained therein is omitted, wherein the viewing direction is toward the front wall of its second housing part facing the first housing part with the hydraulic unit contained therein,

(6) FIG. 5 shows the second housing part with the hydraulic unit of the liquid heating pump of FIG. 4 viewed in the direction of the axial outflow, wherein the rear cover disk of the impeller of the hydraulic unit viewed in the suction direction is omitted,

(7) FIG. 6 shows schematically in a perspective view as a detail of the liquid heating pump of FIG. 4, the diffusor thereof together with the impeller arranged upstream of the wall on the front face thereof, viewed in the axial outflow direction,

(8) FIG. 7 shows schematically in a perspective view an advantageous modification and/or alternative of the diffusor configured according to the invention of FIG. 6, together with the impeller arranged upstream of the wall on the front face thereof, viewed in the axial outflow direction, and

(9) FIG. 8 shows schematically in a perspective view a further advantageous modification of the diffusor configured according to the invention of FIG. 6 with the impeller assigned on the front face.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE PRESENT INVENTION

(10) In FIGS. 1-8, parts corresponding to one another are provided with the same reference numerals. In this case only those components of a household appliance which uses liquid and/or water which are required for understanding the invention are provided and described with reference numerals.

(11) The construction principle according to the invention of a liquid heating pump which is installed in a household dishwasher is described hereinafter. This liquid heating pump may optionally also be provided in other household appliances which use liquids, such as for example in a washing machine, as a component of the washing unit and/or liquid circulation circuit thereof.

(12) FIG. 1 shows in a schematic view a household dishwasher 1 viewed from the side. Said dishwasher comprises a washing container 2 for receiving items to be washed, such as crockery, pans, cutlery, glasses, cooking utensils and the like to be cleaned by liquid and then to be dried. The washing container 2 preferably comprises a substantially rectangular contour (viewed from above) with a front face V facing a user in the operating position. A loading opening which is accessible from the front is present here. This is able to be closed by a front door 3. The door 3 is shown in FIG. 1 in the closed position and, for example, is able to be pivoted up about a horizontal axis 3a. Naturally the loading opening may also be provided at a different point of the washing container, such as for example in the upper face thereof, and is able to be closed and opened by a closure element, such as for example a flap.

(13) In the interior of the washing container 2, one or more receiver containers, such as for example washing baskets 4, 5 for receiving or retaining items to be washed are provided. Here in the exemplary embodiment of FIG. 1 by way of example just two washing baskets and/or crockery baskets 4, 5 are provided on top of one another. The number of washing baskets may be varied depending on the extent and type of household dishwasher 1. Also a so-called cutlery drawer may additionally be provided. These crockery baskets 4, 5 are able to be subjected via one or more spray devices 6, 7, 8 to fresh water FW and/or to circulating water, depending on the partial wash cycle of the wash cycle to be carried out of a dishwashing program, in each case cleaning agent, rinsing agent, and/or other aids being able to be added thereto, i.e. so-called washing liquor liquid and/or washing liquor, and thus generally expressed by washing liquid FL which substantially contains water.

(14) In each case, preferably rotatable spray arms are provided in the interior of the washing container 2 as one or more spray devices. Here in the exemplary embodiment of FIG. 1, for example, two rotatable spray arms 6, 7 are accommodated in the washing container 2, which subject the items to be washed in the crockery baskets 4, 5 in particular to an upwardly oriented spray component. In this case, the lower spray arm 6 is arranged below the lower crockery basket 4. The upper spray arm 7 is arranged below the upper crockery basket 5. Additionally or independently from the two rotatable spray arms 6, 7 other types of spray devices may also be provided. Thus, for example, one or more individual spray nozzles may also be accommodated in a fixed manner in the washing container 2. In the exemplary embodiment of FIG. 1, in addition to the upper rotatable spray arm 7 a spray device 8 is arranged below the upper crockery basket 5 and assigned thereto. It comprises one or more individual nozzles which also convey the liquid FL with an upwardly oriented component to the items to be washed in the upper crockery basket 5. Alternatively, it is also possible to subject the items to be washed to a downwardly oriented spray component. Thus, for example, from the upper spray arm 7 liquid spray jets may also be oriented downwardly onto the items to be washed in the lower crockery basket 4. Also other spray devices are alternatively or additionally possible. Thus on the top wall of the washing container 2 optionally a so-called top spray may be provided, which has been omitted here in FIG. 1 for the sake of illustrative simplicity.

(15) Moreover, the washing baskets 4, 5 may be displaceable to the front, for example on rollers 10, in order for the user to reach an access position in which the user is able to load and unload the washing baskets 4, 5 comfortably. Lateral rails are provided in the washing container 2 as tracks for the rollers 10. Optionally, pull and push handles may be provided on the front edge planes of the washing baskets 4, 5 for simplifying the insertion and extension of the washing baskets 4, 5.

(16) The fresh water FW and/or the circulating washing liquor mixed with cleaning agent, rinse agent, additives and/or dirt from the items to be washed, i.e. in general terms the treatment liquid FL which substantially contains water, passes downwardly, after its distribution in the washing container 2 by being sprayed onto the items to be washed, to a collecting region and/or pump sump 11 which is preferably arranged so as to be recessed in the floor of the washing container 2. Here the liquid passes through a filter unit which is also indicated in dashed lines in FIG. 1. From this collecting region the liquid is conducted in the spraying operation and/or circulating operation of the spray devices to a liquid heating pump 12 fluidically connected to the collecting region 11 and/or suctioned therefrom. The liquid heating pump 12 comprises a circulating pump and in combination therewith additionally a heating device. By means of the circulating pump of the liquid heating pump 12 the liquid is pumped to a distributor unit 14, fluidically connected thereto, in particular a water distribution device, and conducted from there to the spray devices 6, 7, 8. Optionally the distributor unit may also be dispensed with. For pumping out the liquid from the washing container 2 this liquid is pumped out by means of a drainage pump 9 as waste water AW from the washing container 2.

(17) FIG. 2 shows in a schematic longitudinal sectional view a first advantageous exemplary embodiment of a liquid heating pump 12 configured according to the invention. This liquid heating pump comprises two main subassemblies: a first housing part 28 with a drive unit 18 accommodated therein, in particular an electric motor accommodated therein, and a second housing part 29 with a hydraulic unit 19 accommodated therein. In the first housing part 28 the electric motor 18 is mounted such that its drive shaft 20 is substantially oriented in the axial direction AR. The axial direction AR may preferably extend, as here in the exemplary embodiment, substantially horizontally when the liquid heating pump 12 is installed below the floor of the washing container 2 in the floor subassembly of the household dishwasher 1. Alternatively, it may naturally also extend in the installed state so as to deviate from the horizontal, such as for example at an angle of between 10° and 70° to the horizontal. The first housing part 28 is substantially configured to be hollow-cylindrical. The drive shaft 20 protrudes from the front wall of the first housing part 28 facing the hydraulic unit 19 with an end portion. On this end portion of the drive shaft 20 facing the hydraulic unit 19, an impeller 17 is attached fixedly to the front face. This impeller is configured to be substantially circular in cross section, i.e. in a cutting plane to which the rotational axis 191 of the impeller extends in a perpendicular manner. The second housing part 29 with the hydraulic unit 19 accommodated therein forms in the assembled state of the liquid heating pump 12 an axial extension of the first housing unit 28. In this case, the second housing part 29 is also configured to be substantially hollow-cylindrical. The first housing unit 28 and the second housing unit 29 are joined together via preferably releasable coupling means and/or fastening means 30 to form a closed compact pump housing in the axial direction. Both the first housing part 28 with the drive unit 18 accommodated therein and the second housing part 29 with the hydraulic unit 19 accommodated therein are in each case preferably configured to be substantially rotationally symmetrical relative to the rotational axis 191 of the drive shaft 20 and/or the imaginary extension thereof as a central axis of the liquid pump 12.

(18) The hydraulic unit 19 comprises a centrally arranged suction channel 16 for suctioning the liquid FL in an axial suction direction 31 and for supplying the suctioned liquid FL into an impeller chamber 40 arranged axially downstream. The liquid FL is symbolized in FIG. 2 by dots. The central axis 192 of the suction channel 16 in this case is oriented so as to be aligned with the rotational axis and/or central axis 191 of the drive shaft 20. The suction channel 16 is preferably formed by one or more circular cylindrical tubular portions which in each case are arranged concentrically to the central axis 192 of the liquid heating pump 12. If the two housing parts 28 and 29 in the axial direction AR, i.e. relative to their central axes 191, 192, are combined so as to be aligned with one another, the impeller chamber 40 viewed in the suction direction 31, is defined by a rear wall which is formed by one or more wall parts on the front face of the first housing part 28 on which the drive shaft 191 with the impeller 17 fastened at the end thereof protrudes into the impeller chamber 40 counter to the suction direction 31. Moreover, viewed in the suction direction 31, the impeller chamber 40 is defined by a front wall which is formed by one or more wall parts on the front wall of the second housing part 29 which faces the first housing part 28. The suction channel 6 discharges into this front wall of the impeller chamber 40 with its centrally arranged circular outlet opening 401, viewed in cross section, i.e. its central axis 192 is oriented so as to be aligned with the rotational axis 191 of the drive shaft 20. The axial width of the impeller chamber 40 is selected such that between the front wall facing the impeller 17 of the tubular, in particular circular cylindrical, suction channel 16 and the front wall on the suction side of the impeller 17, an axial gap ASP and a radial gap RS remain in order to ensure the free rotatability of the impeller 17. Expediently, the axial gap ASP has an axial width of between 0.5 mm and 1.5 mm and the radial gap RS has an axial width of between 0.5 mm and 1.5 mm.

(19) The impeller here in the exemplary embodiment is preferably configured as a bladed impeller. Viewed in the axial suction direction 31 it has a front cover disk 171 facing toward the suction channel 16 and an opposing rear cover disk 172 in the axial spacing facing the first housing part 28. The blades 174 of the impeller 17 extend between the two cover disks 171, 172. Both the front cover disk 171 and the rear cover disk 172 in each case are curved, viewed from the suction channel 16, in the direction opposing the axial suction direction 31, i.e. to the rear. In particular, in each case they are configured to be concave. In this case a centrally arranged inlet opening 402 which is substantially aligned with the outlet opening 401 of the outlet channel 16 is provided in the front cover disk 171. The rear cover disk 172, however, is designed to be closed. The impeller 17 is attached to the drive shaft 20 such that it is arranged with its rear cover disk 172 in a receiving recess which is recessed in the axial direction AR in the rear wall of the impeller chamber 40 with a predetermined axial gap from the rear wall and thus is freely rotatable, i.e. not in abutment. The curvature of the rear cover disk 172 is extended and/or increased by the wall portion of the rear wall of the impeller chamber surrounding the cover disk, viewed further radially outwardly, substantially without axial offset. Correspondingly, the wall part of the front wall of the impeller chamber 40 surrounding the front cover disk 171 further outwardly, viewed radially, extends the curvature and/or convexity of the inner face of the front cover disk 171 through which liquid flows, substantially without axial offset.

(20) The impeller blades 174 in each case bridge the axial gap spacing between the two axially spaced-apart opposing cover disks 171, 172 and are attached, in particular fastened, to the inner walls thereof facing one another. A liquid through-passage is respectively present between two impeller blades 174 adjacent in the peripheral direction. The blades 174 of the impeller 17 in each case are curved counter to the rotational direction 60 of the impeller 17. The blades extend in each case in the form of a circular arc portion or spiral portion opening outwardly, the radial internal end thereof starting approximately at the peripheral circle of the inlet opening 402 of the front cover disk 171 and the radial outer end thereof approximately ending at the outer periphery and/or external diameter of the front and rear cover disk 171, 172. The respective blade of the impeller is preferably spring-loaded relative to the radial direction (viewed in a normal plane to which the rotational axis 191 extends in a perpendicular manner). If the impeller 17 is driven rotatably by means of the drive unit 18 via the drive shaft 20, the liquid FL present in the impeller chamber 40 is forced away from the center of the impeller 17 outwardly with a radial and circular and/or azimuthal speed component into the radial outer region of the impeller chamber 40. As a result, a greater pressure prevails on the radial outer periphery of the impeller in the impeller chamber 40 than in the center thereof. In this manner, the impeller 40 suctions liquid via the suction channel 16 from the pump sump and/or collecting region 11. The rear curvature of the front cover disk 171 and the rear cover disk 172 and the rear wall assists the liquid conveyed by the impeller to pass through a curved path and to be deflected in the opposing direction to the suction direction 31. This approximate 180° deflection is illustrated in FIG. 2 by the directional arrow 32. In addition to or independently from the geometric shape of the impeller, optionally—as here in the exemplary embodiment of FIG. 2—it may be expedient if the rear wall surface of the impeller chamber and/or the initial portion of the diffusor and/or pressure chamber which, viewed in the flow direction, is immediately downstream of the impeller chamber, also contributes to deflecting the conveyed liquid coming from the axial suction direction 31 by approximately 180° in the opposing direction, i.e. in the axial outflow direction.

(21) In general terms, the impeller has a liquid ejection region around its outer peripheral edge, from which in pumping mode and/or rotational operation (i.e. with the rotating impeller) the liquid is thrown outwardly from the through-passages between its blades. This peripheral liquid ejection region in FIGS. 1-8 is in each case denoted by 173. In the case of the impeller 17 of FIGS. 1-8, the peripheral liquid ejection region is located between the front and the rear cover disks 171, 172.

(22) The liquid FL conveyed in this manner from the impeller 17, then flows into an axially downstream diffusor and/or pressure chamber 50 viewed counter to the suction direction 31. This diffusor and/or pressure chamber is arranged at least along a partial portion of the suction channel 16 outwardly around this suction channel. The diffusor and/or pressure chamber surrounds the suction channel 16 substantially concentrically and/or coaxially. Viewed in cross section, i.e. in a cutting plane transversely to the axial longitudinal extent of the liquid heating pump 12 to which the rotational axis 191 substantially extends in a perpendicular manner, the diffusor and/or pressure chamber 50 is configured to be substantially circular. A diffusor and/or a flow conditioning device 23 which converts the kinetic energy induced by the rotational movement of the impeller 17 into the liquid flow partially into dynamic pressure, is provided in a stationary manner in the diffusor and/or pressure chamber 50. It has a longitudinally extended main body 231 which forms an axially extending partial portion of the internal defining wall or the entire internal defining wall of the diffusor and/or pressure chamber 50. It may be expedient if—as here in the exemplary embodiment of FIG. 2—a tubular portion is provided, in particular integrally formed, on the main body 231 of the diffusor 23 on the inner face, said tubular portion forming an axial partial portion, preferably an end portion assigned to the impeller 17, of the centrally arranged suction channel 16. Additionally or independently thereof, it may be advantageous if the main body 231 of the diffusor 23 is supported on the housing of the centrally arranged suction channel 16 or attached there. In the exemplary embodiment of FIG. 2, the main body 231 is additionally fixed or attached via an axially extending tubular support portion SAB to the housing part 29.

(23) The main body 231 preferably has an elongated substantially circular cylindrical tube, the front wall thereof facing the impeller 17 being configured as a wall around the outlet opening 401 of the suction channel 16 and, viewed in the axial suction direction 31, forming the front defining wall of the impeller chamber 30. This front wall has a circular receiving recess AM1 arranged around the outlet opening of the suction channel 16, for the front cover disk 171 of the impeller 17. The internal contour of this receiving recess in this case substantially corresponds to the outer contour on the suction side of the front cover disk 171. Its axial depth is selected such that the impeller 17 penetrates therein with its front cover disk 171, such that on the inner face of the impeller, a substantially flush continuous transition is produced between the inner wall of the front cover disk 171 and the front surface edge which protrudes relative to the receiving recess AM1 in the direction of the impeller 17 located further radially outwardly, as far as the radial gap RS which remains free, for the free running of the impeller.

(24) The radial outer edge zone of the front wall 233 of the main body 231 facing the suction side of the impeller 17 expediently transitions into the axial longitudinal extent of the axial outer casing 232 of the circular cylindrical main body 231 in the form of a rounded portion AB. This rounded portion AB is also curved to the rear from the suction channel 16, viewed in the axial suction direction 31, in particular in a concave manner. By this rounded portion AB on the front face in the transition from the front wall 233 of the main body 231 into the axial outer casing 232, in particular into the circular cylindrical casing surface, of the main body 231, undesired directional influences, eddy losses or deceleration of the liquid FL ejected from the impeller 17 are substantially prevented. In particular by this rounded portion AB between the radial outer edge zone of the front wall 233 of the main body 231 and the circular cylindrical axial outer casing 232, the reverse path of the liquid flow from the axial suction direction 31 in the 180° opposing direction is promoted. Alternatively to the rounded portion, optionally a recess or groove may be provided on the radial outer edge zone of the front wall 233 of the main body 231 facing the suction side of the impeller 17 as a transition zone between the front wall 233 and the axial outer casing 232.

(25) A heating device 26 which serves for heating the liquid FL conveyed by the impeller 17 is assigned to the diffusor and/or pressure chamber 50. Preferably, the heating device forms a preferably axially extending partial portion or the preferably axially extending entire portion of the outer defining wall of the diffusor and/or pressure chamber 50. As a heating device 26 advantageously a preferably circular cylindrical heating tube HZ is provided extending in the axial direction AR. This heating tube HZ surrounds the circular cylindrical main body 231 from outside substantially concentrically and/or coaxially along an axial partial length or as here in the exemplary embodiment of FIG. 2 substantially along the entire axial length of the main body 231 with a predetermined radial gap spacing 501, such that the diffusor and/or pressure chamber 50 between the axial outer casing 232 of the circular cylindrical main body 231 and the axial inner casing 261 of the circular cylindrical heating tube HZ, viewed in cross section, i.e. viewed in a normal plane to which the rotational axis extends in a perpendicular manner, is configured in the shape of an annular gap.

(26) In the liquid heating pump constructed according to the principle according to the invention which has been successfully tested for mass production in household dishwashers, the radial gap spacing 501 of the diffusor and/or pressure chamber 50 between the axial outer casing 232 of the preferably circular cylindrical main body 231 and the smooth axial inner casing 261 of the preferably circular cylindrical heating tube HZ arranged further radially outwardly relative thereto, is expediently between 3 mm and 8 mm, in particular approximately 5.5 mm. This is a clear reduction, in particular approximately a halving, of the radial gap dimension between the axial outer casing 232 of the main body 231 and the axial inner casing surface 261 of the heating tube HZ through which liquid flows, relative to liquid heating pumps used hitherto in household dishwashers.

(27) Expediently, the in particular circular cylindrical main body of the diffusor in the liquid heating pump configured according to the invention is preferably expanded and/or increased such that the external diameter 503 of its axial outer casing 232 is at least equal to 80%, in particular between 80% and 90%, preferably approximately equal to 86% of the external diameter 505 of the diffusor and/or pressure chamber 50 and/or the external diameter 505 of the outer defining wall 261 of the diffusor and/or pressure chamber 50. This leads to a reduction in the annular gap-shaped through-passage surface in the diffusor and/or pressure chamber, such that with an equal volumetric flow of liquid FL provided by the impeller 17, the flow speed through the diffusor and/or pressure chamber 50 is increased, such that in a reliable manner sufficient heat is dissipated by the liquid FL conveyed by the rotating impeller from the heating device 26, as may be ensured in this case in the exemplary embodiment from the axial inner casing surface 261 of the circular cylindrical heating tube HZ, through which the liquid flows. Additionally, the dead space volume in the pump housing for the liquid to be conveyed may be reduced. The reduction in the annular cross-sectional passage surface in the diffusor and/or pressure chamber 50 is associated with an improved displacement effect for the liquid flowing through. This results in a reduction in the total quantity of liquid circulating in the liquid heating pump according to the invention. As a result, the so-called transfer of dirty liquor may be further reduced, which may occur when changing the washing bath, i.e. when the washing bath quantity used for a water-conducting partial wash cycle of a dishwasher program is pumped out partially or entirely by means of the drainage pump from the washing container of the dishwasher and fresh water for the next water-conducting partial wash cycle of this dishwasher program, for a further washing bath, is introduced into the washing container. Since the circulating pump of the liquid heating pump during the drainage process of the previously completed partial wash cycle is generally switched off, dirty washing liquid used from this previous water-conducting partial wash cycle remains therein and only when the liquid heating pump is started up again in the following partial wash cycle is this quantity of already used washing water pumped out of the liquid heating pump from the pump housing and in the course of the partial wash cycle introduced via the one or more spray devices into the washing container. Due to the reduced dead space volume in the liquid heating pump according to the invention also less water may be used overall per washing bath. By the reduction of the circular passage cross section of the diffusor and/or pressure chamber additionally the flow speed of the liquid flowing through is increased. As a result, an improved dissipation of the heating power provided by the heating device to the liquid flowing through the diffusor and/or pressure chamber is ensured. This is associated with a reduced temperature load of the heating device 26. The surface of the heating device 26 in contact with the conveyed liquid, in this case in the exemplary embodiment of FIG. 2 the inner wall surface 261 of the preferably circular cylindrical heating tube HZ, tends therefore less to the formation of limescale deposits which impair the heat transfer from the heating device 26 to the liquid FL, here from the inner wall surface 261 of the heating tube HZ to the liquid flowing through said heating tube, and associated therewith tends less to the formation of so-called hot spots, i.e. local overheating points which may lead to thermal and/or electrical damage of the heating device.

(28) Correspondingly, for the diffusor and/or pressure chamber in the exemplary embodiment of FIG. 2, the diameter 505 of the impeller chamber 40 is also increased relative to the external diameter 504 of the impeller 17. Here it is selected to be approximately equal to the diameter of the outer defining wall of the diffusor and/or pressure chamber. As a result, an initial portion of the heating device 26 may even be accommodated in the impeller chamber 40, and then extend further into the diffusor and/or pressure chamber 50 arranged downstream. In particular, an initial portion of the heating device 26 forms a partial portion or the entire portion of the outer defining wall of the impeller chamber. In this manner, the axial length of such an advantageously configured liquid heating pump may be shortened relative to previous liquid heating pumps, so that (in comparison with a construction in which the initial portion of the heating device only starts in the diffusor and/or pressure chamber) less installation space is required in the floor subassembly of the dishwasher 1 of FIG. 1.

(29) In summary, in the exemplary embodiment here, the heating device is expediently provided by a heating tube HZ which forms the outer defining wall 261 of the diffusor and/or pressure chamber 50 along a partial length or the entire length of the axial extent thereof. The heating tube HZ may, in particular, comprise, for example, a circular cylindrical metal tube, the conveyed liquid flowing over the smooth inner casing surface thereof and/or inner wall surface 261 thereof. On its outer casing surface, remote from the diffusor and/or pressure chamber 50, it preferably has an electrical insulating layer with heat conductors attached thereto on the outer face. The heat conductors may expediently be covered outwardly by an additional covering layer, in particular an electrical insulating layer. The electrical insulating layer, the heat conductor tracks and/or the covering layer may, in particular, be applied by a thick film technique or by a physical gas phase deposition method, such as for example PVD (physical vapor deposition) method. Naturally, other types of heating tubes are also possible.

(30) In a liquid heating pump constructed according to the principle according to the invention, such as for example 12, which has been tested successfully for mass production in household dishwashers, the heating device 26 for heating up the washing liquid to a desired temperature in the respective partial wash cycle, such as for example during a cleaning cycle or rinsing cycle, of a dishwashing program to be carried out, preferably provides an electrical surface thermal load of between 30 W/cm.sup.2 and 50 W/cm.sup.2. For the heat dissipation thereof, by means of the liquid FL conveyed in the pumping mode, in this case the cross-sectional passage surface QF of the annular gap-shaped diffusor and/or pressure chamber 50, viewed in cross section, is advantageously selected to be between 8 cm.sup.2 and 20 cm.sup.2, in particular approximately 12 cm.sup.2. This dimensioning is advantageous, in particular, if the impeller—in particular with an external diameter of approximately 4.2 cm—expediently revolves at between 3800 and 4800 rpm, in particular 4200 rpm in pumping mode. In this case the external diameter of the impeller, in particular, is selected to be between 3.8 and 4.5 cm, preferably approximately 4.2 cm. The circular cylindrical diffusor main body of this successfully tested liquid heating pump expediently has an external diameter of approximately 6.2 cm and the heating tube an internal diameter of approximately 7.3 cm.

(31) In summary, the liquid heating pump 12 comprises a centrally arranged suction channel 16 for suctioning the liquid FL in an axial suction direction 31 and for supplying the suctioned liquid into an impeller chamber 40 arranged axially downstream. In the impeller chamber 40 an impeller 17 is provided to be rotatably drivable, in order to convey the liquid into a diffusor and/or pressure chamber 50 arranged axially downstream, viewed counter to the suction direction 31. This diffusor and/or pressure chamber is preferably coaxially arranged around an axial partial portion or the axial entire portion of the suction channel 16 on the outside. A stationary diffusor 23 is assigned to the diffusor and/or pressure chamber 50. This diffusor has an, in particular, circular cylindrical main body 231, the front wall 233 thereof facing the impeller 17 forming a defining wall of the impeller chamber 40 on the suction side, i.e. on the front, and the axial outer casing 232 thereof forming, in particular, the axially extending partial portion or the entire portion of the inner defining wall of the diffusor and/or pressure chamber 50 extending, in particular, axially. Additionally, the heating device assigned to the diffusor and/or pressure chamber 50 for heating the conveyed liquid FL expediently forms at least one, in particular axially extending, partial portion or the entire portion of the outer defining wall 261 of the diffusor and/or pressure chamber 50, in particular extending axially.

(32) Downstream of the diffusor and/or pressure chamber 50 concentrically arranged around the suction channel 16, viewed counter to the suction direction 31, i.e. in the axial outflow direction, is a housing outlet 271 preferably extending with an axial extent in a helical and/or spiral-shaped manner with an assigned tubular discharge port 272, branching off laterally, in particular approximately tangentially on the outlet side for ejecting the liquid FL. The outflow direction of the conveyed liquid, facing upwardly in the exemplary embodiment of FIG. 2, is indicated by a directional arrow 34. The central axis ZA of the discharge port 272 is positioned obliquely relative to the radial direction RR counter to the axial suction direction 31, i.e. in the outflow direction, preferably by an acute angle SWI, in particular between 5° and 20°, preferably approximately 10°. Naturally, if required it is possible to provide to the housing outlet 271 and/or the discharge port 272 a path which deviates from the axial spiral housing or a geometric shape which deviates therefrom.

(33) The liquid heating pump 12 is expediently installed in a bottom support and/or a floor subassembly below the floor of the washing container 2, such that the discharge port 272 protrudes from the second housing part 29 upwardly in the direction of the floor of the washing container 2. The liquid heating pump 12 is thus installed with a rotational axis extending substantially in the horizontal and/or in the axial direction of its drive shaft and thus is installed in the dishwasher 1 so as to be located in the floor subassembly below the floor of the washing container 2. As the outlet 271 is preferably configured with the discharge port 272 as an outwardly opening spiral portion which is integrally formed on the second housing part 29 on the front wall remote from the first housing part 28, and opposing the cross-sectional plane to which the rotational axis 191 extends in a perpendicular manner, and extends counter to the axial suction direction 31 and/or counter to the direction of gravity obliquely by an acute angle, the liquid flow which preferably moves in the diffusor and/or pressure chamber 50 in the form of a helix and/or helical line migrating counter to the suction direction 31 in the axial outflow direction toward the discharge port may be conveyed out of said discharge port by continuing this flow movement from the discharge port 272. As a result, hydraulic losses are substantially prevented, i.e. the hydraulic efficiency of the liquid heating pump is improved. In FIG. 2 this helical flow path of the liquid FL in the diffusor and/or pressure chamber and downstream thereof into the discharge port 272 is indicated by the flow arrow 33.

(34) Within the scope of the invention the hydraulic-mechanical efficiency, in particular, encompasses the pressure losses and frictional losses in the components of the liquid heating pump. The volumetric efficiency thereof, however, is determined, in particular, by any leakage losses which are present.

(35) In contrast or alternatively to the advantageous spatial-geometric shape of the impeller chamber and/or the impeller arranged therein of the exemplary embodiment of FIG. 2, optionally other designs of the impeller chamber and/or the impeller may also be expedient, provided these ensure in each case that liquid from the pump sump 11 is suctioned through the suction channel 16 in the axial suction direction 31 into the impeller chamber 40 and is able to be deflected there by approximately 180° in the opposing direction into the diffusor and/or pressure chamber 50 arranged downstream, and at the same time the liquid in the impeller chamber may be provided with a sufficient speed component by the rotational movement of the impeller in the radial direction and in the circular direction. Thus, for example, it may also be sufficient to accommodate an open impeller in the impeller chamber on the suction side. In particular, it may be expedient if, instead of simply curved blades, the impeller comprises three-dimensionally curved blades, i.e. so-called 3D blades. Advantageously—as here in the exemplary embodiment of FIG. 2—a so-called half-axial, half-radial impeller is used. Instead of this, a so-called radial impeller may also be accommodated in the impeller chamber 40. In the exemplary embodiment of FIG. 2 a so-called closed impeller is provided in which the impeller blades on both sides are connected to one respective disk. This increases the hydraulic efficiency and stabilizes the impeller.

(36) Generally, the problem occurs in impellers, the rotating impeller blades thereof setting the liquid in rotation, i.e. subjecting the liquid to a circular speed component, that by means of centrifugal forces air collects in the center of the impeller chamber and/or around the hub 175 of the impeller and the liquid through-passages between the blades thereof “block up”. If air collects in the center of the impeller chamber during rotational operation of the impeller, the impeller is no longer able to create sufficient pressure in order to suction liquid through the suction channel from the pump sump and to convey the liquid through the impeller chamber and the downstream diffusor and/or pressure chamber out of the discharge port on the outlet side.

(37) In order to counteract a collection of air in the center of the impeller chamber 40 and/or about the hub 175 of the impeller, i.e. to prevent this as far as possible, according to the construction principle according to the invention one or more guide blade portions 24 which axially protrude in the direction of the impeller chamber 40 are provided on the front wall 233 facing the impeller chamber 40 of the preferably circular cylindrical main body 231 of the diffusor 23 in the exemplary embodiment here. In the exemplary embodiment of FIG. 2 advantageously three axially protruding guide blade portions 241, 242, 243 are attached to the front wall 233 of the main body 231 facing the impeller chamber, in particular integrally formed. FIG. 4 shows the liquid heating pump 12 of FIG. 2 schematically in a perspective view in the open state. In this case, the first housing part 28 with the preferably electrical drive unit 18 contained therein is omitted. The viewing direction is toward the front wall of the second housing part 29 facing the first housing part 28, with the hydraulic unit 19 contained therein. Corresponding to FIG. 4, FIG. 5 now shows in a front view the front wall of the open second housing part 29 of the liquid heating pump 12 of FIG. 2 facing the first housing part 28, when viewed in the axial outflow direction, wherein the rear cover disk 172 of the impeller 17 of the hydraulic unit 19, viewed in the suction direction 31, is also omitted. Finally, FIG. 6 illustrates schematically in a perspective view, as a detail of the liquid heating pump 12 of FIG. 4, the diffusor 23 thereof together with the impeller 17 arranged downstream of the wall 233 thereof on the front face (viewed in the suction direction 31).

(38) The three axially protruding guide blade portions 241, 242, 243 are fixedly arranged on the front wall of the stationary main body 231 facing the impeller chamber in the peripheral direction, in each case offset to one another by the same centering angle of approximately 120° such that a liquid guide channel such as for example RK12 is present between two adjacent axially protruding guide blade portions, viewed in the peripheral direction, such as for example 241, 242, away from the peripheral liquid ejection region 173 of the impeller 17, said liquid guide channel in the front wall 233 of the main body 231 which faces the impeller chamber 40 leading outwardly to the axial outer casing 232 of the main body 231. As a result, three liquid guide channels RK12, RK23, RK31 are provided, starting from the outer peripheral and/or peripheral liquid ejection region 173 of the impeller 17 to the axial outer casing 232 of the main body 231. In detail, viewed in the rotational direction 60 of the impeller 17, the liquid guide channel RK12 is provided between the first axially protruding guide blade portion 241 and the second axially protruding guide blade portion 242, downstream in the peripheral direction, the liquid guide channel RK23 is provided between the second axially protruding guide blade portion 242 and the third axially protruding guide blade portion 243, downstream in the peripheral direction, and the liquid guide channel RK31 is provided between the third axially protruding guide blade portion 243 and the first axially protruding guide blade portion 241, downstream in the peripheral direction. The respective axially protruding guide blade portion 241, 242, 243 extends in this case approximately from the peripheral circle which is predetermined by the peripheral liquid ejection region 173 on the outer periphery of the impeller 17 as far as the outer periphery of the circular cylindrical main body 231. In this case, it is attached, in particular integrally formed, onto the closed cover surface 233 of the circular cylindrical main body 231 facing the impeller chamber 40, which extends between the outer periphery of the outlet opening 401 of the suction channel 16 and the outer periphery of the main body 231. Preferably it may be produced from the same plastics material as the main body 231, in this case as the circular cylindrical cover thereof. In general terms, the respective axially protruding guide blade portion is made from a single material and is integrally formed on the front face 233 of the main body 231 facing the impeller chamber 40. In this manner, the respective guide blade portion 241, 242, 243 axially protruding into the impeller chamber 40 extends inside the outer periphery of the preferably circular cylindrical main body 231 here, but not beyond the axial outer casing of the main body in the radial direction. At least its initial portion AA covers the axial width AB of the liquid outlet region 173 between the two cover disks 171, 172 of the impeller 17. Viewed in the radial direction RR, a radial gap RS which is as small as possible remains between the initial portion A of the respective axially protruding guide blade portion 241, 242, 243 and the outer periphery of the impeller. In particular, the radial gap RS is selected to be between 0.5 mm and 2 mm. As a result, circular leakage volumetric flows, which could circulate once or repeatedly around the outer periphery of the impeller 17, are substantially prevented. This improves, in particular, the volumetric efficiency of the liquid heating pump 12 constructed according to the invention. Preferably the respective axially protruding guide blade portion 241, 242, 243 covers the entire axial extent ABR of the peripheral liquid outlet region 173 along its entire extent which here in the exemplary embodiment reaches as far as the outer periphery of the circular cylindrical casing 232 of the main body 231.

(39) The respective axially protruding guide blade portion 241, 242, 243 extends such that, viewed from its further radially inwardly located initial portion A as far as its further radially outwardly located end E, it has an oblique position of in particular between 90° and 135°, preferably of approximately 120°, relative to the radial direction RR of the impeller 17 in the rotational direction 60 thereof. As a result, it forms for the liquid ejected from the liquid ejection region 173 of the impeller 17, with a radial and circular and/or azimuthal speed component, a slope rising from the peripheral liquid outlet region 173 to the outer periphery of the axial outer casing 232, i.e. it forms a lifting aid which brings the liquid FL ejected from the impeller 17 onto a defined guide path which leads from the peripheral liquid ejection region 173 to the axial outer casing 232 of the main body 231. In particular, the respective axially protruding guide blade portion 241, 242, 243 has an arcuate shape with a direction of curvature in the rotational direction 60 of the impeller 17. This path of the respective axially protruding guide blade portion 241, 242, 243 lifts the liquid ejected from the impeller with a radial and circular directional component from the respective outlet point thereof on the peripheral liquid ejection region 173 and guides the liquid in a defined manner outwardly to an inlet on the axial outer casing 232 of the main body 231, which is different from the outlet, (viewed in the rotational direction 60) into the diffusor and/or pressure chamber 50. It is expedient, in particular, if when viewing the front wall 233 of the main body 231 of the diffusor 23 facing the impeller chamber 40, the respective axially protruding guide blade portion, such as for example 241, with its further radially inwardly located initial portion AA preferably extends outwardly, substantially tangentially, from an internal peripheral point on the circle of the liquid ejection region 173 of the impeller 17 and with its radially outwardly located end portion EA discharges substantially tangentially on an outer peripheral point on the outer peripheral circle of the axial outer casing 232 of the main body 231, which is different from this internal peripheral point. This advantageously promotes the removal of the conveyed liquid from the peripheral outer periphery of the impeller in a flow path to the axial outer casing of the main body and into the preferably circular cylindrical diffusor and/or pressure chamber, where it continues to circulate in the axial direction around the preferably circular cylindrical axial outer casing of the main body in a helical manner. In this regard, the kinetic energy provided by the rotating impeller to the liquid is partially maintained when the impeller chamber transitions into the diffusor and/or pressure chamber. To this end, in particular, it is advantageous if the respective axially protruding guide blade portion, as in the exemplary embodiment here of FIGS. 2-6, viewed in the viewing direction of the front wall 233 in the axial outflow direction, extends from its further radially inwardly arranged initial portion A to its further radially outwardly arranged end E relative thereto, in the form of an outwardly opening circular arc portion or spiral portion. It is particularly advantageous if the respective axially protruding guide blade portion extends in the form of a spiral portion, the radius of curvature thereof increasing from its further radially inwardly arranged initial portion A to its further radially outwardly arranged end E relative thereto.

(40) The three axially protruding guide blade portions 241, 242, 243 are integrally formed on the wall 233 of the main body 231 on the front face facing the impeller chamber 40, such that in each case, viewed from their further radially inwardly located initial portion A to their further radially outwardly located end E, they extend in the peripheral direction, in each case via a predetermined centering angle range of preferably between 45° and 90° (viewed in the rotational direction 60) in the successfully tested liquid heating pump and in this case, in the plane spanned by this front wall 233 of the main body 231 or a plane parallel thereto, cover a radial slope and/or a radial distance which corresponds approximately to the radial spacing RA between the liquid ejection region 173 and the axial outer casing 232 of the main body 231. The respective axially protruding guide blade portion thus serves firstly as removal means and/or a lifting aid (in the radial direction) for the liquid FL on the outer periphery of the impeller ejected further radially inwardly therefrom, into the further outwardly located diffusor and/or pressure chamber 50, viewed radially. Secondly, the freely axially protruding guide blade portions, viewed around the outer periphery of the impeller, serve as interruption means in the peripheral direction which prevent the formation of a single or repeated 360° circular flow in the impeller chamber. In other words, they remove the liquid ejected on the outer periphery of the impeller 17 from the peripheral liquid outlet region 173 thereof, in the direction of the axial outer casing 232 of the main body 231 in a defined manner and in good time, so that it barely results in a circular flow which circulates once or repeatedly by 360°, or not at all.

(41) In the successfully tested liquid heating pump for mass production in a household dishwasher which is constructed according to the principle according to the invention, the radial spacing RA is between 5 mm and 10 mm. The respective axially protruding guide blade portion 241, 242, 243 preferably has an axial extent of between 3 mm and 8 mm, in particular of approximately 5 mm. By the axially protruding guide blade portions 241, 242, 243 which are arranged offset to one another approximately in the peripheral direction, by the same centering angle of approximately 120°, and which in each case viewed in the peripheral direction approximately cover an angular range of between 45° and 90°, the liquid flow which flows out of the impeller 17 at the peripheral liquid outlet region 173 thereof may be acted upon substantially uniformly by a radial and circulating deflection component and, viewed in the peripheral direction, the liquid is distributed substantially uniformly into the diffusor and/or pressure chamber 50 which is circular in cross section.

(42) In order to ensure that the liquid, which emerges from a peripheral point on the outer peripheral and/or peripheral liquid outlet region 173 of the impeller 17, is still able to pass from there along a partial angular range of a full 360° angle around the impeller in the rotational direction 60 before it is deflected and/or diverted by an axially protruding guide blade portion, positioned downstream in the rotational direction 60, in the direction of the axial outer casing, in particular as in the exemplary embodiment here advantageously to the axial outer casing 232 of the main body 231, it is expedient if the respective axially protruding guide blade portion, viewed from its further radially inwardly located initial portion A to its further radially outwardly located end E relative thereto, in the peripheral direction extends over an angular range of at least 30° and at the same time in each case in the plane spanned by the front wall 233 of the main body 231, preferably covers a radial slope RA which corresponds to the radial spacing between the liquid ejection region 173 of the impeller 17 and the axial outer casing 232 of the main body 231.

(43) Between the imaginary, in particular tangential, extension of the radial outer end portion of the respective impeller blade 174 and the imaginary, in particular tangential, extension of the initial portion AA of the respective axially protruding guide blade portion 241, 242, 243, preferably an acute intermediate angle WI of at most 50°, in particular of between 30° and 45°, is enclosed. In the liquid heating pump successfully tested for mass production in household dishwashers, the intermediate angle WI is advantageously selected to be approximately equal to 41°. The intermediate angle WI is made up from the outlet angle AW which is enclosed between the tangential extension of the outer end portion of the respective impeller blade 174 and the tangent which at the intersection between the outer impeller blade end and the outer peripheral circle of the impeller 17 is positioned thereon, and the inlet angle EW, which is enclosed between the tangent on the initial portion AA of the respective axially protruding guide blade portion, such as for example 241, and the tangent which at the intersection of the initial portion AA of the guide blade portion, such as for example 241, with the outer peripheral circle of the impeller 17, is positioned thereon. In order to be able to lift the liquid ejected from the blades of the impeller from the outer periphery of the impeller and/or the circular liquid ejection region 173 thereof to a liquid path which leads to the axial outer casing 232 of the main body 231 and at the same time keeps losses of kinetic energy, which has been provided to the liquid by the rotational movement of the impeller blades, as low as possible or prevents losses as far as possible, the inlet angle EW is expediently selected to be less than 15°, in particular between 8 and 12°.

(44) In this manner, the respective guide blade portion, such as for example 241, 242, 243, for the liquid ejected on the outer periphery of the impeller has a guide track and/or a guide path which, relative to the flow path thereof provided by the impeller blades, has a slighter larger pitch in order to force the liquid from the outer peripheral circle 173 of the impeller 17 away into an ascending path leading to the axial outer casing 232 of the diffusor main body. As the intermediate angle WI is selected, in particular, to be at most equal to 50°, the losses of kinetic energy may be kept low when supplying the liquid emerging from the liquid ejection region 173 to the respective axially protruding guide blade portion.

(45) The further radially inwardly located initial portion A of the respective axially protruding guide blade portion, such as for example 241, 242, 243, expediently has a contour which is different from the contour of the outlet side end of the respective impeller blade. In this case in the exemplary embodiment of FIGS. 2-6, the initial portion A of the respective axially protruding guide blade portion extends in the form of a bevel transversely to the end contour of the outlet side end of the respective blade of the impeller. Expediently, an acute angle of SW between 20° and 60° is enclosed between the edge extending the axial direction of the outer end of the respective impeller blade and the edge of the initial portion A, positioned transversely to this impeller blade end edge, of the respective axially protruding guide blade portion. By the different contours of the impeller blade end and the initial portion of the respective axially protruding guide blade portion inadmissibly high noise excitation by the liquid ejected from the impeller and striking the initial portion A of the respective axially protruding guide blade portion is substantially prevented.

(46) Here in the exemplary embodiment of FIGS. 2-6, additionally on the axial outer casing 232 of the main body 231, three radially protruding guide blade portions 251, 252, 253, viewed in the rotational direction 60, in each case are arranged offset to one another by approximately the same peripheral angle of preferably approximately 120°. In the liquid heating pump successfully tested for mass production, these three radially protruding guide blade portions 251, 252, 253 acting on the liquid flow in the diffusor and/or pressure chamber 50 with an axial directional component, in each case protrude radially between 2 mm and 3 mm from the axial outer casing 232 into the diffusor and/or pressure chamber 50. They extend in each case in the form of a helix portion and/or helical portion around an axial longitudinal portion of the circular cylindrical main body 231. The helix portion of the respective radially protruding guide blade portion 251, 252, 253 in this case begins at the end of the axial outer casing 232 facing the impeller chamber 40, i.e. at the axial longitudinal point of the main body, from which it extends into the axial outflow direction. In the liquid heating pump tested for mass production, the respective helical radially protruding guide blade portion has an axial pitch, preferably of between 2.5 and 3.5 cm, in particular of approximately 3 cm, on the axial outer casing. Downstream of the portion provided with the three radially protruding guide blade portions 251, 252, 253 of the circular cylindrical main body 231, viewed in the axial outflow direction, is an end portion of the main body which is free of guide blades. This has an axial length, preferably of between 2 cm-5 cm for the liquid heating pump tested for mass production.

(47) The further radially outwardly arranged end portion EA of the respective guide blade portion axially protruding on the front face, such as for example 241 in this case in the exemplary embodiment of FIGS. 2-6 via a connecting portion VA in particular integrally formed thereon, is connected to an assigned, radially protruding guide blade portion, such as for example 251, arranged downstream on the outer casing side, viewed in the rotational direction 60 of the impeller 17. In this case, the connecting portion VA ensures a substantially continuous, uninterrupted, i.e. continual transition between the end portion EA of the guide blade portion axially protruding on the front wall 233 of the main body 231, such as for example 241, and the initial portion of the radially protruding guide blade portion, for example 251, assigned thereto on the axial outer casing 232 of the main body 231. The connecting portion VA is removed from the liquid ejection region 173 of the impeller 17 preferably by a spatial distance which approximately corresponds, viewed in a normal plane to the rotational axis, to the radial distance between the outer periphery of the impeller 17 and the outer periphery of the front wall 233. In the liquid heating pump successfully tested for mass production in household dishwashers, the connecting portion VA is preferably spatially removed between 0.8 cm and 1.2 cm from the impeller 17.

(48) The connecting portion VA extends along an outer peripheral portion of the front wall 233 of the main body 231 facing the suction side of the impeller 17. It has an axially protruding circular arc-like projecting portion AST which, viewed in the cross-sectional plane of the front wall 233 and/or when viewing from the impeller chamber to the front wall 233, is attached, in particular integrally formed, on the outer edge of the front wall 233 along a portion of the circular arc-shaped outer periphery thereof.

(49) Additionally on the front face of this axially protruding circular arc portion-like projecting portion AST facing the impeller chamber 40, a radially protruding projecting portion RST is attached, in particular integrally formed, along the entire length thereof. The radially protruding projecting portion RST in this case forms an edge angled at approximately 90° to the axially protruding projecting portion AST. It may be advantageous in this case, in particular, if the axial extent of the axially protruding projecting portion AST, from its end facing the axially protruding guide blade portion, such as for example 241, continuously reduces as far as its end facing the radially protruding guide blade portion, such as for example 251, on the axial outer casing side. As a result, it is possible in a structurally simple manner to lengthen the radially protruding guide blade portion on the axial outer casing side, such as for example 251, preferably corresponding to the spiral-shaped path thereof. Viewed in the plane of the front wall 233 the axially protruding projecting portion AST, however, lengthens the axially protruding guide blade portion on the front face, such as for example 241, by a circular arc portion, which is integrally formed on a peripheral edge portion of the outer periphery of the front wall. If the axially protruding guide blade portion, such as for example 241, viewed in the plane of the front wall 233 is configured to be in the manner of a spiral portion, the axially protruding projecting portion AST according to an alternative embodiment may correspondingly lengthen this spiral portion path of the axially protruding guide blade portion, such as for example 241, in the downstream direction.

(50) In this manner, the connecting portion VA connects the axially protruding guide blade portion on the front face, such as for example 241, with the radially protruding guide blade portion assigned thereto on the axial outer casing side, such as for example 251, preferably integrally and in a single material to form a continuous guide blade. As a result, the hydraulic efficiency of the liquid heating pump constructed according to the invention and the aeration behavior thereof is particularly improved. This is because the radially protruding projecting portion RST acts counter to the axial outflow direction as a barrier and/or obstacle which hinders or prevents an axial flow of an air bubble from the diffusor and/or pressure chamber back into the impeller chamber and thus ultimately into the center of the impeller chamber, when the liquid heating pump is operating in pumping mode. The axially protruding projecting portion AST serves as an extension of the radial outer end portion of the axially protruding guide blade portion of the combined guide blade and preferably permits a continuous transition into the radially protruding guide blade portion assigned thereto on the axial outer casing side. Additionally it acts in the impeller chamber counter to the radial ejection direction of the impeller as a barrier and/or obstacle which hinders or prevents a flow of an air bubble from the diffusor and/or pressure chamber radially inwardly back into the center of the impeller chamber when the liquid heating pump is working in pumping mode.

(51) If as here in the exemplary embodiment of FIGS. 2-6 three axially protruding guide blade portions are provided on the front face 233 of the diffusor main body 231 facing the impeller chamber 40, offset to one another by approximately 120° in the rotational direction 60, in particular the following angular distribution is expedient: the respective guide blade portion 241, 242, 243 axially protruding on the front face, viewed in the peripheral direction, extends over a centering angle range W241, W242, W243 of between 50° and 90°, its connecting portion VA viewed in the peripheral direction extends over a centering angle range of between 30° and 60°, and the radially protruding guide blade portion 251, 252, 253 assigned thereto on the axial outer casing side extends over a centering angular range of between 50° and 90°. The diffusor 23 in its installed position is expediently positioned to be aligned such that one of the three guide blade portions, such as for example the guide blade portion 241, viewed in the polar coordinate system, extends in the angular range of between 10° and 90°, its connecting portion VA extends in the angular range of between 90° and 135° and the radially protruding guide blade portion assigned thereto on the axial outer casing side, such as for example 251, extends in the angular range of between 135° and 205°. As a result, it is substantially prevented that an air bubble, in particular from the 12 o'clock region, i.e. from the upper zone of the diffusor and/or pressure chamber 50 when starting up the liquid heating pump 12 constructed according to the invention, is able to flow back into the impeller chamber 40 counter to the predetermined pump outflow direction. When viewing the front wall of the main body 231 facing the impeller chamber 40, (viewed from the impeller) the respective radially protruding guide blade portion, such as 251 for example, extends on the axial outer casing 232 of the main body 231, and its extension on the upstream side extends through the radially protruding projecting portion RST of the connecting portion VA in an outer peripheral region of the main body 231, in the gap between the radial outer end E of a first axially protruding guide blade portion, such as for example 241, and the radial outer end E of an adjacent second axially protruding guide blade portion, viewed in the rotational direction 60 of the impeller 17, such as for example 242. The radially protruding projecting portion RST of the connecting portion VA in this case produces an axial barrier for an air bubble which is located on the downstream side of the connecting portion VA in the diffusor and/or pressure chamber 50, so that in rotational operation of the impeller 17 this air bubble is prevented from flowing back into the impeller chamber 40. Such an air bubble may be present in an upper cavity of the housing part 29, in particular after a stoppage phase of the impeller of the liquid heating pump, and in the case of a conventional liquid heating pump, when starting up the impeller, this air bubble could flow back into the center of the impeller chamber (by the active centrifugal forces which project the liquid outwardly due to the greater density thereof, while by the vacuum produced in the center of the impeller chamber the air flows therein).

(52) Viewed in the installed position of the diffusor 23, in particular, the first axially protruding guide blade portion 241 and its connecting portion VA for the first radially protruding guide blade portion 251 assigned thereto on the axial outer casing side is arranged in the upper region of the main body 231, such that they prevent any air bubble which is present above the main body 231 in the diffusor and/or pressure chamber 50 from flowing back radially inwardly in the direction of the center of the impeller chamber 30 during the rotational operation of the impeller. This is advantageous, in particular, when during start-up, i.e. when starting the impeller, an air bubble is present in an upper cavity of the second pump housing part 29, in particular in the upper region of the diffusor and/or pressure chamber 50 or the outlet 271 optionally downstream thereof.

(53) Optionally it may be sufficient, in particular, to provide in the liquid heating pump a simplified diffusor which has only a single combined guide blade (as specified above) with an angular position in the upper region of the main body. A simple means for preventing an air bubble from flowing back into the center of the impeller chamber may even be provided thereby. In a further simplified manner, it may be sufficient, in particular, if only one single axially protruding guide blade portion is provided in the 12 o'clock region of the front face of the main body facing the impeller chamber, the circular cylindrical main body otherwise being configured on its axial outer casing without guide blades.

(54) Returning to the exemplary embodiment of FIGS. 2-6, the respective axially protruding guide blade portion, such as for example 241, on the front wall 233 of the main body 231 facing the impeller chamber 30, terminates on the outer periphery of the main body in the peripheral position in which the upstream radially protruding guide blade portion on the axial outer casing, viewed in the rotational direction 60 of the impeller 17, such as for example 253, viewed downstream on the axial outer casing 232 of the main body 231 (in the direction of the discharge port 272) terminates with an axial spacing from the front wall 233 of the main body 231 of the diffusor 23 facing the impeller chamber 40. This ensures that by means of two tool parts and/or mold parts which may be moved in the axial direction toward one another and away from one another, the diffusor may be produced in a simple manner in a plastics injection-molding method and fault-free unmolding of the radially protruding and axially protruding guide blade portions on the main body of the diffusor is possible.

(55) By these combined, i.e. 3D, guide blades which in each case are made up from a guide blade portion axially protruding on the front face, a connecting portion and an associated radially protruding guide blade portion, the kinematic energy provided to the liquid ejected by the impeller may be converted with a high level of efficiency into pressure. The guide blades additionally permit short transit times for air bubbles which may potentially enter the suction channel on the input side. For the liquid heating pump successfully tested for mass production, a transit time preferably of at most 6 seconds, in particular of between 3 and 6 seconds, elapses between the time when an air bubble enters the suction channel and the time when it is ejected from the discharge port.

(56) FIG. 7 shows schematically in a perspective view a modification of the diffusor 23 of FIGS. 2-6. The modified diffusor is denoted by 23*. Viewed in the outflow direction (i.e. in the 180° direction opposing the suction direction 31), the impeller 17 is arranged upstream of the front face thereof facing the impeller chamber. This diffusor 23* has no combined guide blades but on the front face of the main body 231 of the modified diffusor 23* facing the impeller chamber and/or the suction side, three individual separate guide blade portions 241*, 242*, 243* protrude axially in the direction of the impeller. The guide blade portions are in each case arranged offset to one another by approximately the same angle of approximately 120° in the peripheral direction. The path thereof otherwise corresponds to that of the axially protruding guide blade portions 241, 242, 243 of the diffusor 23 of FIGS. 2-6. Individual radially protruding guide blade portions 251*, 252*, 253* are provided in each case separated by a gap from the axially protruding guide blade portions 241*, 242*, 243* on the axial outer casing of the main body of the diffusor 23*. The guide blade portions have approximately the same spiral portion-shaped path as the radially protruding guide blade portions 251, 252, 253 on the axial outer casing 232 of the main body 231 of the diffusor 23 of FIGS. 2-6. The respective axially protruding guide blade portion, such as for example 241*, viewed in the peripheral direction, is positioned such that viewed in the axial direction it preferably covers the gap between a first radially protruding guide blade portion, such as for example 253*, and, viewed in the rotational direction 60 of the impeller, a downstream radially protruding guide blade portion, such as for example 251*. Also it may be substantially prevented thereby that when starting up the impeller and/or during rotational operation of the impeller an air bubble which is located in the upper, approximately 12 o'clock, region of the diffusor and/or pressure chamber is able to flow back to the center of the impeller chamber. This modified diffusor 23*, by the separate axially protruding guide blade portions 241*, 242*, 243*, and the radially protruding guide blade portions 251*, 252*, 253* separated therefrom, i.e. unconnected thereto, may be produced in a simple manner by means of two tool parts which may be moved in the axial direction toward one another and away from one another in a plastics injection-molding method. In this case, fault-free unmolding of the separate radially protruding guide blade portions and the separate axially protruding guide blade portions unconnected thereto on the main body of the diffusor is possible.

(57) Finally FIG. 8 shows schematically in a perspective view a second modification of the diffusor 23 of FIGS. 2-6. In this case in turn the impeller (viewed in the axial outflow direction) is illustrated upstream of the front face of the main body of the diffusor facing the impeller chamber. The modified diffusor is illustrated in FIG. 8 by 23**. The guide blade portions 251-253 radially protruding on the axial outer casing of the main body are omitted therein. The diffusor has only the guide blade portions 241, 243 axially protruding into the impeller chamber 30. The respective axially protruding guide blade portion 241-243 is, in particular, configured to be enlarged by the axially protruding arcuate projecting portion AST. The respective axially protruding guide blade portion 241, 242, 243 on the front face 233 of the main body 231 facing the impeller chamber 30 in the direction of the impeller 17 protrudes on its further radially outwardly located end portion EA less in the axial direction of the impeller than on its further radially inwardly located initial portion AA. By this shape of the respective axially protruding guide blade portion, in the plane of the front face of the main body facing the impeller chamber, a lifting aid for the liquid ejected from the running impeller is provided in a simple manner on the otherwise smooth circular cylindrical axial outer casing of the main body and a barrier is provided to prevent an air bubble from flowing back radially inwardly from the diffusor and/or pressure chamber.

(58) In a modification of the advantageous variants of FIGS. 1-8, optionally it may even be sufficient to provide only a single axially protruding guide blade portion approximately in the 12 o'clock region, i.e. in the upper region of the front wall 233 of the main body 231 of the diffusor facing the impeller chamber. Also a barrier, which is located downstream in the upper region of the diffusor and/or pressure chamber, may even be provided in the direction of gravity and/or vertical direction LO to prevent an air bubble from flowing radially inwardly back to the center of the impeller chamber. This is advantageous, in particular, when starting up the impeller.

(59) Particularly advantageous are three axially protruding guide blade portions corresponding to the exemplary embodiments of FIGS. 2-8. These guide blade portions are preferably in each case arranged offset to one another in the peripheral direction by approximately 120°. Correspondingly, it is expedient if three radially protruding guide blade portions in each case are arranged offset by approximately 120° in the peripheral direction on the axial outer casing of the main body of the diffusor, as is the case in the exemplary embodiments of FIGS. 2-8. Due to this number, the production of the diffusor remains simple. At the same time, the liquid in the impeller chamber and diffusor and/or pressure chamber which, viewed in cross section, is configured to be circular, may be acted upon substantially uniformly.

(60) Optionally two axially protruding guide blade portions may also be sufficient on the front face of the main body of the diffusor facing the impeller chamber. The guide blade portions then expediently subdivide the peripheral liquid outlet region, viewed around the outer periphery of the impeller, into approximately 180°—sized angular ranges. Also a circular flow may even be subdivided thereby into two 180° components so that it does not result in the formation of a circular flow which circulates around 360°.

(61) Advantageously, there may be up to six axially protruding guide blade portions. These guide blade portions are then, in particular, in each case arranged offset to one another by approximately 60° in the peripheral direction and in each case assigned to a peripheral angular range of between 40° and 60°. Expediently, a plurality of radially protruding guide blade portions on the axial outer casing of the main body may be correspondingly assigned to these axially protruding guide blade portions.

(62) Within the scope of the invention, in particular, the following features may also be expedient individually or in combination:

(63) In the interior of the pump chamber, a stator and/or diffusor with guide blades is fastened fixedly in terms of rotation concentrically around the suction channel. This stator and/or this diffusor has a main body which is preferably configured to be circular cylindrical. It is, in particular, increased by expansion of its external diameter as a solid body toward the heating surface of the heating tube and/or heating pipe which preferably forms an axial partial portion or the entire portion of the outer defining wall of the diffusor and/or pressure chamber. Expediently, the main body of the diffusor is configured as a hollow body. By increasing the external diameter of the main body, the radial extent, i.e. the radial height, of the spiral-shaped axially acting guide blade portions reduces proportionally. The diffusor and/or pressure chamber which is circular in cross section and through which water and/or liquid flows, also correspondingly reduces in cross section, whereby with the same volumetric flow the flow speed in this region increases, as does the heat transfer to the cylinder wall of the heating pipe heated from outside. The water volume and/or liquid volume in the interior of the diffusor and/or pressure chamber also correspondingly reduces. By the novel geometry of the main body of the stationary stator and/or stationary diffusor on the stator, guide blades protruding in the axial direction and thus radially acting on the liquid ejected from the impeller, may be directly placed around the impeller, in particular the bladed impeller, which noticeably improve the aeration behavior of the hydraulic unit after the introduction of air, when changing the liquid and water or when changing the water distribution device. On the front wall of the main body facing the impeller chamber advantageously one or more axially protruding guide blade portions are provided, preferably in addition to one or more guide blade portions radially protruding on the axial outer casing of the main body. In this case, one respective radially protruding guide blade portion and one respective axially protruding guide blade portion assigned thereto of the stator, can preferably directly transition into one another and form a combined guide blade pair protruding axially and radially and transitioning into one another in a 3D-like manner. These additional radially acting guide blade portions which in each case protrude in the axial direction on the front face of the main body facing the impeller chamber, in particular the combined 3D-type axially radially protruding guide blade pairs, which transition into one another, provide a significant improvement with regard to the entire operating behavior of the liquid heating pump constructed according to the invention. Noise excitation of the water by the axially protruding blade edges may be reduced or prevented by beveling or rounding the blade edges on which the water flows and which face the impeller, in particular the bladed impeller. The diameter of the stator, the number, height, pitch and/or curvature of the axially and radially protruding guide blade portions and the position thereof may accordingly be optimized for the desired results. The fastening of the stator in the pump housing may take place by orienting the angular position, in particular by a latching connection, frictional welding, ultrasonic welding, laser welding, mirror welding, bonding, and/or by simple axial clamping between other components of the hydraulic unit. With an airtight seal of the stator interior from the remaining hydraulics, positive effects on hygiene, water consumption, transfer of dirty liquor and frost resistance may be anticipated. This may be implemented by additional sealing elements and by forming as a two-component plastics part or cost-effectively by welded connections. The geometry of the stator may preferably be designed such that a cost-effective production by plastics injection-molding is possible by means of simple open-closed molds without slides.

(64) Increasing the external diameter of the main body of the diffusor results in a reduced dead space in the diffusor and/or pressure chamber for water by the displacement effect in the hydraulic chamber and a resulting reduction in the circulating water quantity, with correspondingly less transfer of dirty liquor between washing baths, and overall less water used per washing bath. The increased flow speed of the water on the heated surface of the heating device also results in an improved heat dissipation, with a reduced temperature load of the heating system, with the resulting reduced tendency to the formation of limescale deposits and hot spots. The combination of radial and axial guide blade portions improves the aeration behavior of the pump after changing the water, switching the spraying plane or in the case of spin losses. The liquid heating pump constructed according to these advantageous features, therefore, has a reduced tendency for malfunctioning in extreme operating conditions. It is also characterized by an improved efficiency of its hydraulic part and/or its hydraulic unit by optimized flow guidance. In summary, its overall performance, reliability and service life is improved. The liquid heating pump configured according to the construction principle according to the invention exhibits a low failure rate, which could be caused by limescale deposits from the water on the surface of the heating pipe on which the liquid flows. Thus the heat transfer from the heating pipe to the water is improved. An impairment of the heat transfer between the heating pipe and the water as a result of limescale deposits, and in a self-energizing manner due to “PTC effects”, for example on heating conductors which are attached to the outer face of the heating pipe, and thus associated “hot spots”, are reduced or prevented. At such points the heating system would otherwise malfunction, due to overheating and heat dissipation of the electrical insulating layer of the heating pipe. The hydraulic and volumetric efficiency of the liquid heating pump configured in such a manner are improved, the aeration time thereof is reduced and the water volume present therein reduced. By increasing the flow speed and optimizing the flow guidance on the surface of the heating pipe on which the liquid flows, the formation of limescale deposits may be reduced or prevented or—if limescale deposits have been formed—the removal thereof may be accelerated.