Impeller pump

Abstract

An impeller pump has a pump casing including a pump chamber and an inlet and an outlet thereon and an impeller therein, and including a heating device for heating the conveyed medium, which heating device forms an external wall of the pump chamber. The pump chamber extends annularly around the impeller and away from the pump chamber floor, wherein the outlet leads off on a region of the pump chamber which, viewed in the axial direction of the impeller pump, is pointing away from the pump chamber floor. The cross-sectional area of the pump chamber decreases in the axial direction of the longitudinal center axis of the impeller pump away from the pump chamber floor toward the outlet by virtue of an obliquely inwardly inclined external wall.

Claims

1. An impeller pump for the conveyance of a medium, comprising: a pump casing comprising a pump chamber and an inlet and an outlet thereon; an impeller, disposed in said pump chamber, behind said inlet and before said outlet within a conveyance path; and a heating device to heat said conveyed medium, said heating device forming at least part of an external wall of said pump chamber, wherein said impeller is arranged on a pump chamber floor and, starting therefrom, said pump chamber extends annularly around said impeller and away from said pump chamber floor, and wherein said outlet leads off on a region of said pump chamber which, viewed in an axial direction of the impeller pump, is pointing away from said pump chamber floor, wherein a cross-sectional area of said pump chamber decreases continuously in said axial direction of a longitudinal center axis of said impeller pump away from said pump chamber floor and toward said outlet, and wherein said outlet runs in a direction at right angles to said axial direction, wherein said heating device is tubular in configuration, and wherein said heating device is rotationally symmetrical to said longitudinal center axis, wherein it is configured such that it tapers conically away from said pump chamber floor.

2. The impeller pump according to claim 1, wherein said decrease is uniform, with an angle of an oblique external wall of said pump chamber to said longitudinal center axis of said impeller pump from 3° to 25°.

3. The impeller pump according to claim 2, wherein said angle of said oblique external wall of said pump chamber to said longitudinal center axis of said impeller pump ranges from 5° to 15°.

4. The impeller pump according to claim 1, wherein a radially inner wall of said pump chamber runs straight and parallel to said longitudinal center axis of said impeller pump, and with constant radius.

5. The impeller pump according to claim 4, wherein said radially inner wall of said pump chamber has constant shape.

6. The impeller pump according to claim 1, wherein said heating device runs around at least a major part of said pump chamber.

7. The impeller pump according to claim 6, wherein said heating device runs fully around said pump chamber.

8. The impeller pump according to claim 1, wherein an output per unit of area of said heating device, viewed over a basic region of said heating device, is the same.

9. The impeller pump according to claim 1, wherein said heating device lies on a side outside said pump chamber.

10. The impeller pump according to claim 1, wherein said inlet ends at less than 50% of a height of said pump chamber in said axial direction.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) Illustrative embodiments of the invention are represented schematically in the drawings and are explained in greater detail below. In the drawings:

(2) FIG. 1 shows a lateral sectional view through an inventive pump comprising a pump chamber tapered by a conical shape of an external wall,

(3) FIG. 2 shows a variation of the pump from FIG. 1, comprising a pump chamber tapered by a conical shape of internal wall and external wall, and

(4) FIG. 3 shows a top view of the pump from FIG. 1.

DETAILED DESCRIPTION

(5) In FIG. 1, an inventive impeller pump is represented in sectioned side view. The pump 11 has a pump casing 12, comprising a pump chamber 13. An inlet 15 leads into the center of the pump chamber 13 and an outlet 16 leads out at the upper rim. It can be seen that the inlet 15 is axially aligned with the longitudinal center axis 17 (shown in dashed representation), while the outlet 16, as is also shown by the top view from FIG. 3, runs at right angles thereto or tangentially to the circumferential pump chamber 13. The pump chamber 13 is limited in the downward direction substantially by an external wall 19 and an internal wall 20, as well as by a pump chamber floor 21. It can also be seen that the height of the pump chamber 13 in the axial direction has roughly four to six times the width of the pump chamber 13 close to the pump chamber floor 21, namely in the radial direction.

(6) Just above the pump chamber floor 21 rotates an impeller 23, which reaches to close to the inlet 15 and is driven by a pump motor (not represented) via a motor shaft 24. The rotational direction of the impeller 23 is in FIG. 3 counterclockwise and in FIG. 1 on the left of the impeller 23 out of the plane of the drawing and on the right into the plane of the drawing, as is represented by appropriate symbols. In this respect, the structure of the pump 11 substantially corresponds to the prior art stated in the introduction, in the form of EP 2150165. Liquid which is to be conveyed and heated, in particular water in a dishwasher, washing machine or the like, is introduced to the inlet 15 along the longitudinal center axis 17 and is discharged by the rotating impeller 23 in the radial direction, namely just above the pump chamber floor 21. The liquid has a circulating direction corresponding to the rotational direction of the impeller 23. At the same time, it rises further and further upward in the pump chamber 13, mainly along the external wall 19, until it finally after several revolutions, advantageously three to ten revolutions, is fed out to the outlet 16. In the pump chamber, it is hereupon warmed. This is respectively illustrated by the three arrows, wherein the arrow in the pump chamber 13 shows only the upward motional component and not the predominant motional component in the circulating direction in the pump chamber.

(7) Since the pump casing 12 according to FIG. 3 is substantially, except for the outlet 16, of rotationally symmetrical configuration, it is evident that the cross section of the pump chamber 13, which along the circulating direction at an axial height is always the same, tapers from the pump chamber floor 21 or from the impeller 23 and toward the outlet 16. In particular, the width of the pump chamber 13 right at the top beneath the apex or just in front of the outlet 16 amounts to only about 40% of the width at the height of the impeller 23. This is therefore a significant reduction in the cross-sectional area of the pump chamber. Here it can also be seen that the internal wall 20 stands at right angles to the plane of the pump chamber floor 21, and the angle β between its course and the perpendicular to the pump chamber floor 21 or to the longitudinal center axis 17 measures 0°. The internal wall 20 also runs straight.

(8) The external wall 19 likewise runs straight, but stands at an angle α of about 10° to the perpendicular to the pump chamber floor 21. Thus the external wall 19 is tilted inward or slanted by α=10°.

(9) It can further be seen that the internal wall 20 is configured in one piece with the inlet 15, as well as with the upper region of the pump casing 12, configured virtually as a cover, from which also the outlet 16 leads off in one piece. This part is advantageously made of plastic. The largest region of the external wall 19 (also referred to herein as outer wall 19) is configured as a heating device 26, as is fundamentally known also from the external wall of EP 2150165. There, however, the heating device is of circularly cylindrical and straight configuration, i.e. of constant cross-sectional area, which is specifically not the case here. The heating device 26 represented on the left in FIG. 1 has a support as part of the external wall 19, which support advantageously consists of metal or a special steel. On its outer side, as is known, once again, from the prior art, it is at least partially provided with an insulation, to which, once again, heating elements are applied. In the case of the heating device 26 represented on the left, these are heating elements 28a to 28e, which are configured, for example, as broadly circumferential resistance strips, advantageously in a thick-film heating element. They can be electrically connected to one another in parallel. It can be seen that the width of the heating elements 28 decreases away from the pump chamber floor 21 toward the outlet 16, and thus the heat generation in the upward direction increases due to the cumulative effect of heating elements 28a to 28e.

(10) On the right in FIG. 1, a heating device 26′ comprising a planar heating element 28′ is represented. This is meant primarily to illustrate that here, unlike on the left side, the output per unit of area in the direction away from the pump chamber floor 21 remains the same for the heating device 26′.

(11) The principal technical effect of the decrease in cross-sectional area or the tapering of the pump chamber 13 from bottom to top consists in the fact that here the flow velocity is increased. This promotes a heat removal from the heating device 26. Specifically in connection with the heating device 26 (represented on the left) with upwardly increasing output per unit of area of the heating means, this is of advantage. In this way, a better heating of the conveyed medium or of the conveyed liquid can be achieved without local overheating of the heating device 26.

(12) It can be seen that the external wall 19 is formed above the heating device 26 by the plastics part of the pump casing 12. A sealed connection between these two parts is easily realizable for the person skilled in the art, for example by means of rubber seals. Although the heating device 26 could also be extended still higher, there are then, however, design problems on account of the outlet 16. In similar form, a seal can also be made between the lower region of the heating device 26 or 26′ and the pump chamber floor 21.

(13) In the variation of the invention as a pump 111 according to FIG. 2 (shown in simplified representation), a pump casing 112 comprising a pump chamber 113 is once again provided, as well as an inlet 115, an outlet 116 and a longitudinal center axis 117 (shown in dashed representation). An external wall 119 is once again slanted relative to the longitudinal center axis 117 or to a pump chamber floor 121. However, it can here clearly be seen that the angle α′ is smaller than in FIG. 1 and advantageously is only 5°. Here too, however, an internal wall 120 of the pump casing 112 is obliquely inclined, namely obliquely outward. An angle β′ here likewise measures 5° in accordance with the angle α′, though this is not absolutely necessary. Likewise, as a result, a pump chamber 113 of, in the direction away from the pump chamber floor 121, reduced cross-sectional area, i.e. an upwardly tapered pump chamber 113, is thereby obtained.

(14) With respect to the heating device 126, as a large part of the external wall 119 of the pump chamber 113, a planar heating element 128 is shown in purely general representation. For this heating element 128, the same design options as in FIG. 1, or even yet further options, can apply.

(15) The top view of the pump 11 according to FIG. 1, which is represented in FIG. 3, is meant essentially to illustrate to what extent the pump 11 or the pump casing 12 without the outlet 16 is of rotationally symmetrical, i.e. circular configuration. This applies above all to the external wall 19 and the internal wall 20. This rotational symmetry is not essential, however, though it is simple and advantageous for the manufacture of the pump, in particular as regards the manufacture of the heating device 26 as a fundamental component of the external wall 19.