PISTON PUMP FOR A HIGH PRESSURE CLEANING DEVICE

Abstract

A piston pump for a high pressure cleaning device is provided, having a pump housing, which includes a first housing part and a second housing part. The first housing part forms a suction conduit and a pressure conduit, and the second housing part forms a plurality of pump chambers each in flow connection with the suction conduit by an inlet channel and with the pressure conduit by way of an outlet channel. The first insert part includes an inlet valve seat and a guide member arranged offset from said inlet valve seat. The inlet closing body includes an inlet valve stem that adjoins the inlet valve plate and is displaceably mounted on the guide member. The first insert part includes an annular inlet valve seat body that points toward the pump chamber and forms the inlet valve seat, wherein the guide member is arranged upstream of the inlet valve seat.

Claims

1. A piston pump for a high pressure cleaning device for conveying a cleaning liquid, having a pump housing, which comprises a first housing part and a second housing part that are each configured as a metal part, wherein the first housing part forms a suction conduit and a pressure conduit, and wherein the second housing part forms a plurality of pump chambers into each of which a reciprocally movable piston dips and which are each in flow connection with the suction conduit by way of an inlet channel and with the pressure conduit by way of an outlet channel, wherein the inlet channel can be closed by an inlet valve and the outlet channel can be closed by an outlet valve, wherein the inlet valve comprises a first insert part inserted into the inlet channel and an inlet closing body that is reciprocally displaceable relative to the first insert part, wherein the first insert part comprises an inlet valve seat and a guide member arranged offset from the inlet valve seat, and wherein the inlet closing body comprises an inlet valve plate that can sealingly abut against the inlet valve seat and an inlet valve stem that adjoins the inlet valve plate and is displaceably mounted on the guide member, wherein the first insert part consists of a plastic material and comprises an annular inlet valve seat body, which points toward the pump chamber and forms the inlet valve seat, wherein the guide member is arranged upstream of the inlet valve seat relative to the flow direction of the cleaning liquid.

2. The piston pump in accordance with claim 1, wherein the inlet valve seat body protrudes out of the inlet channel in the direction of the pump chamber.

3. The piston pump in accordance with claim 2, wherein the second housing part forms an annular first support surface that adjoins the inlet channel in the direction of the pump chamber and is oriented perpendicularly to a longitudinal axis of the inlet channel and against which the inlet valve seat body abuts with an abutment surface.

4. The piston pump in accordance with claim 3, wherein the inlet valve seat body comprises a sealing ring receptacle, which adjoins the abutment surface and in which a sealing ring that seals off the inlet valve seat body relative to the first support surface is arranged.

5. The piston pump in accordance with claim 4, wherein the sealing ring receptacle forms an annular groove surrounding the inlet valve seat body in the circumferential direction, with a first groove wall that adjoins the abutment surface and is adjoined by a second groove wall, wherein the outer diameter of the inlet valve seat body increases commencing from the second groove wall with increasing proximity to the abutment surface.

6. The piston pump in accordance with claim 5, wherein the outer diameter of the inlet valve seat body increases over the second groove wall with increasing distance from the abutment surface.

7. The piston pump in accordance with claim 1, wherein the first insert part comprises at least one holding arm, which adjoins the inlet valve seat body in the direction of the suction conduit and is held in a rotationally-fixed manner relative to the inlet channel.

8. The piston pump in accordance with claim 7, wherein the at least one holding arm engages behind the inlet channel on its side pointing toward the suction conduit.

9. The piston pump in accordance with claim 7, wherein the at least one holding arm is materially bonded to the inlet valve seat body.

10. The piston pump in accordance with claim 7, wherein the first insert part comprises two diametrically opposed holding arms with respect to a longitudinal axis of the inlet channel.

11. The piston pump in accordance with claim 7, wherein the guide member is fixed to the at least one holding arm.

12. The piston pump in accordance with claim 7, wherein the guide member is materially bonded to the at least one holding arm.

13. The piston pump in accordance with claim 7, wherein the at least one holding arm comprises an end portion, which points away from the inlet valve seat body and dips into a recess of the second housing part.

14. The piston pump in accordance with claim 13, wherein the end portion of the at least one holding arm forms a positive engagement with the recess.

15. The piston pump in accordance with claim 13, wherein the end portion of the at least one holding arm is thermally deformable.

16. The piston pump in accordance with claim 1, wherein the first insert part forms a one-piece plastic molded part.

17. The piston pump in accordance with claim 1, wherein the inlet valve stem passes through the guide member and comprises a stem portion, which protrudes out of the guide member in the direction of the suction conduit and to which a spring holder is fixed, wherein an inlet valve spring is clamped between the spring holder and the guide member.

18. The piston pump in accordance with claim 17, wherein the guide member forms a stop, which delimits the movement of the inlet valve plate in the direction of the pump chamber.

19. The piston pump in accordance with claim 1, wherein the second housing part comprises a valve receptacle into which the outlet channels open, and wherein the piston pump comprises an outlet valve assembly that forms all outlet valves, wherein the outlet valve assembly comprises a second insert part, which consists of a plastic material and is inserted into the valve receptacle and comprises a plurality of annular outlet valve seat bodies, which each form an outlet valve seat.

20. The piston pump in accordance with claim 19, wherein the outlet valve assembly is configured as a unit that can be preassembled.

21. The piston pump in accordance with claim 19, wherein the second housing part in the region of the valve receptacle forms a plurality of annular second support surfaces, which are oriented perpendicularly to a longitudinal axis of the valve receptacle and each adjoin an outlet channel in the flow direction of the cleaning liquid and against each of which a respective outlet valve seat body abuts with the interposition of a sealing ring.

22. The piston pump in accordance with claim 19, wherein the outlet valves each comprise an outlet closing body, which is reciprocally displaceable relative to the second insert part and which comprises an outlet valve plate that can sealingly abut against an outlet valve seat and comprises an outlet valve stem adjoining the outlet valve plate in the direction pointing away from the outlet channel.

23. The piston pump in accordance with claim 22, wherein the outlet valve assembly comprises a guide body, which consists of a plastic material and comprises a plurality of guide elements on each of which an outlet valve stem is displaceably mounted.

24. The piston pump in accordance with claim 23, wherein the guide elements each form a guide receptacle into which an outlet valve stem dips.

25. The piston pump in accordance with claim 24, wherein the guide receptacles each comprise at least one inner groove extending in the longitudinal direction of the guide receptacles.

26. The piston pump in accordance with claim 23, wherein a respective outlet valve spring is clamped between the guide elements and the outlet valve plates.

27. The piston pump in accordance with claim 23, wherein the guide body is connectable to the second insert part in a releasable and liquid-tight manner.

28. The piston pump in accordance with claim 23, wherein the guide body forms a check valve seat for a central check valve arranged downstream of the outlet valves relative to the flow direction of the cleaning liquid.

29. The piston pump in accordance with claim 1, wherein the first housing part comprises a housing recess oriented in alignment with the valve receptacle, into which the guide body dips with the interposition of at least one sealing ring.

30. The piston pump in accordance with claim 29, wherein the at least one sealing ring surrounds the guide body in the circumferential direction.

31. The piston pump in accordance with claim 29, wherein the guide body comprises an outwardly protruding annular projection, with which a radially inwardly directed step of the housing recess of the first housing part is associated, wherein a sealing ring is arranged between the projection and the step.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] FIG. 1 shows a section view of a piston pump;

[0058] FIG. 2 shows an enlarged partial view of the piston pump from FIG. 1;

[0059] FIG. 3 shows an enlarged section view of detail X from FIG. 2, which shows an outlet valve assembly of the piston pump;

[0060] FIG. 4 shows a perspective depiction of a second housing part of the piston pump;

[0061] FIG. 5 shows an enlarged section view of detail Y from FIG. 2, which shows an inlet valve of the piston pump;

[0062] FIG. 6 shows a section view of the inlet valve from FIG. 5 along line 6-6;

[0063] FIG. 7 shows a perspective depiction of a first insert part of the inlet valve from FIG. 5 before the assembly thereof,

[0064] FIG. 8 shows a section view of the first insert part from FIG. 7;

[0065] FIG. 9 shows a perspective depiction of the first insert part of the inlet valve after the assembly thereof,

[0066] FIG. 10 shows a section view of the first insert part from FIG. 9;

[0067] FIG. 11 shows a section view of the outlet valve assembly from FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

[0068] An advantageous embodiment of a piston pump, in accordance with the invention, for a high pressure cleaning device is schematically depicted in the drawing and is denoted as a whole with the reference numeral 10. A cleaning liquid, preferably water, can be conveyed by means of the piston pump 10. The piston pump 10 comprises a pump housing 12 with a first housing part 14 and a second housing part 16. The two housing parts 14, 16 are each configured as a metal part. In the depicted embodiment, they are each configured in the form of an aluminum die-cast part.

[0069] The first housing part 14 defines the front side 18 of the piston pump 10 and forms a suction conduit 20 and a pressure conduit 22. The second housing part 16 forms three pump chambers into each of which a piston dips. For a better overview, only one pump chamber 24 and two pistons 26, 28 are shown in the drawing. All pistons are pushed into the respective pump chamber 24 by a swash plate known per se, which is not shown in the drawing, and pushed back out of the pump chamber by a coil spring 30 surrounding the respective piston, such that the volume of the pump chambers 24 changes periodically.

[0070] Each pump chamber 24 is in flow connection with the suction conduit 20 by way of an inlet channel 32 of the second housing part 16. Each pump chamber 24 is in flow connection with the pressure conduit 22 by way of an outlet channel 34 of the second housing part 16. The inlet channels 32 are oriented in parallel to one another and each have a longitudinal axis 33.

[0071] Two diametrically opposed recesses 36, 38 of the second housing part 16 adjoin the inlet channels 32 on the side pointing toward the suction conduit 20. This is made clear in particular in FIG. 4. A respective annular first support surface 40, which is formed by the second housing part 16 and faces toward the respective pump chamber 24, adjoins each of the inlet channels 34 in the direction of the pump chambers 24. This is clear in particular from FIGS. 2 and 5. The first support surfaces are oriented perpendicularly to the longitudinal axes 33.

[0072] Cleaning liquid to be pressurized can be sucked via the inlet channels 32 into the respective pump chamber 24, and the cleaning liquid can be dispensed via the outlet channels 34 from the pump chambers 24. The outlet channels 34 open into a central valve receptacle 42 of the second housing part 16, which is delimited in the circumferential direction by a cylinder wall 44. The valve receptacle 42 is arranged on the side of the second housing part 16 pointing toward the first housing part 14 and has a longitudinal axis 43 which is oriented in parallel to the longitudinal axes 33 of the inlet channels 32.

[0073] The first housing part 14 comprises a housing recess 46 on its side pointing toward the second housing part 16, which is oriented in alignment with the valve receptacle 42 of the second housing part 16 and which is adjoined by the pressure conduit 22 in the direction of the front side 18 of the first housing part 14.

[0074] From the housing recess 46 branches off a bypass conduit 48, which is formed from the first housing part 14 and in which a bypass valve 50 is arranged, which is known per se and therefore is only schematically depicted in the drawing. The bypass conduit 48 establishes a flow connection between the housing recess 46 and the suction conduit 20 and can be closed by means of the bypass valve 50.

[0075] The inlet channels 32 can each be closed by a respective inlet valve 52. The inlet valves 52 are of identical configuration and each comprise a first insert part 54, which consists of a plastic material, preferably of a POM material, and which is inserted into an inlet channel 32. In addition, the inlet valves 52 each comprise an inlet closing body 56, which is reciprocally movable relative to the first insert part 54 in the axial direction.

[0076] The first insert part 54 comprises an inlet valve seat body 60, which forms an inlet valve seat 62 of the respective inlet valve 52. The inlet valve seat body 60 protrudes into the respectively associated pump chamber 24 and is supported with an abutment surface 64 pointing away from the respective pump chamber 24 on the first support surface 40 adjoining the respective inlet channel 32 in the direction of the pump chamber 24.

[0077] The abutment surface 64 is adjoined by a sealing ring receptacle 66 in the form of an annular groove 68, which extends over the circumference of the inlet valve seat body 60 and comprises a first groove wall 70 directly adjoining the abutment surface 64 and a second groove wall 72 adjoining said first groove wall 70. The outer diameter of the inlet valve seat body 60 decreases continuously over the first groove wall 70 with increasing distance from the abutment surface 64, and the outer diameter of the inlet valve seat body 60 continuously increases over the second groove wall 72 with increasing distance from the abutment surface 64. This is clear, in particular, in FIGS. 7 and 9.

[0078] The sealing ring receptacle 66 accommodates a first sealing ring 74, which seals off the inlet valve seat body 60 in the axial direction relative to the first support surface 40.

[0079] The inlet valve seat body 60 of the first insert part 54 is adjoined in the direction of the suction conduit 20 by two diametrically opposed holding arms 76, 78 with respect to the longitudinal axis 33 of the inlet channel 32, which pass through the inlet channel 34 and each comprise an end portion 80, 82 pointing away from the inlet valve seat body 60, which protrudes out of the inlet channel 32 on the side of the inlet channel 32 pointing away from the pump chamber 24 and, in the assembled state of the inlet valve 52, engages behind the respective inlet channel 32 by dipping into a recess 36, 38 of the second housing part 16 and forming a positive engagement therewith. This is described in more detail below.

[0080] The holding arms 76, 78 accommodate an annular guide member 84 between them in the region of the inlet channel 32. The outer diameter of the guide member 84 is smaller than the diameter of the inlet channel 32. This allows the cleaning fluid to flow around the guide member 84 within the inlet channel 32.

[0081] The guide member 84 is materially bonded to the holding arms 76, 78, and the holding arms 76, 78 are materially bonded to the inlet valve seat body 60.

[0082] In the depicted embodiment, the first insert part 54 forms a one-piece plastic molded part, which defines the inlet valve seat body 60, the holding arms 76, 78, and the guide member 84.

[0083] The inlet closing body 56 comprises an inlet valve plate 88 and an inlet valve stem 90, which adjoins said inlet valve plate 88 in one piece on the side of the inlet valve plate 88 pointing away from the pump chamber 24. The inlet valve plate 88 can sealingly abut against the inlet valve seat 62 of the inlet valve seat body 60, and the inlet valve stem 90 extends through the guide member 84 in the direction toward the section conduit 20.

[0084] A spring holder 94 is fixed to a stem portion 92 of the inlet valve stem 90 that protrudes out of the guide member 84 in the direction of the suction conduit 20. An inlet valve spring 96 is clamped between the spring holder 94 and the guide member 84. The inlet valve spring 96 is configured as a coil spring, which is supported on the spring holder 94 on the one hand and on the guide member 84 on the other hand, and surrounds the inlet valve stem 90 in the circumferential direction in the region between the guide member 84 and the spring holder 94. Under the action of the inlet valve spring 96, the inlet valve plate 88 connected to the inlet valve stem 90 in one piece is pressed against the inlet valve seat 62 of the inlet valve seat body 60, such that the inlet valve 52 adopts its closing position.

[0085] When the piston 26, 28 dipping into the respective pump chamber 24 moves in the direction pointing away from the inlet channel 32, the inlet valve 52 thus opens by the inlet valve plate 88 lifting off from the inlet valve seat 62 against the spring force of the inlet valve spring 96 and thereby unblocking a flow connection from the suction conduit 20 to the pump chamber 24, such that cleaning liquid is able to flow from the suction conduit 20 via the inlet channel 32 into the pump chamber 24. The cleaning fluid can hereby flow around the spring holder 94, the inlet valve spring 96, and the guide member 84 on the outside, such that flow losses can be kept to a minimum.

[0086] The inlet valve plate 88 can lift off from the inlet valve seat 62 so far that the spring holder 94 comes into abutment against a stop 98 of the guide member 84 configured as a projection or a sleeve. The stop 98 thus delimits the lifting movement of the inlet valve plate 96.

[0087] When the piston 26, 28 moves in the direction of the inlet channel 32, the inlet valve plate 88 thus adopts its position on the inlet valve seat, such that the cleaning liquid cannot flow back into the suction conduit 20.

[0088] For the assembly of the inlet valve 52, in a first assembly step, the first insert part 54 can be inserted with initially rectilinearly oriented holding arms 76, 78, as they are depicted in FIGS. 7 and 8, from the side pointing toward the pump chamber 24 into the inlet channel 32, such that the abutment surface 64 comes into abutment against the first support surface 40 and the end portions 80, 82 of the holding arms 76, 78 protrude out of the inlet channel 32 on the side of the inlet channel 32 pointing away from the pump chamber 24. The end portions 80, 82 can then be thermally reshaped, the end portions 80, 82 being pushed radially outwardly and dipping into the recesses 36, 38 and with them in each case forming a positive engagement. As a result, the first insert part 54 is held on the inlet channel 32 in an axially immovable and rotationally-fixed manner. In a further assembly step, the inlet closing body 56 can then be mounted on the first insert part 54 by inserting the inlet valve stem 90 from the side pointing toward the pump chamber 24 into the first insert part 54, wherein the inlet valve stem 90 passes through the guide member 84. The inlet valve spring 96 can then be placed on the stem portion 92 protruding out of the guide member 84 on the side pointing away from the pump chamber 24, and then the spring holder 94 can be fixed to the stem portion 92. The fixing of the spring holder 94 to the stem portion 92 may be effected, for example, by means of ultrasonic welding.

[0089] The outlet channels 34 opening into the valve receptacle can each be closed by a respective outlet valve 99. The outlet valves 99 are of identical configuration and are formed by an outlet valve assembly 100 that can be pre-assembled and that is accommodated by the valve receptacle 42 of the second housing part 16 and the housing recess 46 of the first housing part 14.

[0090] The outlet valve assembly 100 is shown enlarged in FIGS. 3 and 11. It comprises a second insert part 102, which consists of a plastic material, for example of a POM material. The second insert part 102 is inserted into the valve receptacle 52 and comprises a plurality of annular outlet valve seat bodies 104, each forming an outlet valve seat 106 of an outlet valve 99.

[0091] In addition to the second insert part 102, the outlet valve assembly 100 comprises a guide body 108, which also consists of a plastic material, for example of a fiber-reinforced plastic material, and which is connectable to the second insert part 102 in a releasable and liquid-tight manner. The guide body 108 forms guide elements 110 in the form of guide receptacles 112, which are oriented in alignment with an outlet valve seat 106.

[0092] The second insert part 102 and the guide body 108 accommodate between them a plurality of outlet closing bodies 114, which are reciprocally displaceable relative to the second insert part 102 and to the guide body 108 and each comprise an outlet valve plate 116 and an outlet valve stem 118 of an outlet valve 99 adjoining said outlet valve plate 116 in one piece. The outlet valve plate 116 can sealingly abut against an outlet valve seat 106, and the outlet valve stem 118 adjoining the outlet valve plate 116 on the side thereof pointing away from the outlet valve seat 106 dips into a guide receptacle 112, in which it is displaceably mounted.

[0093] Clamped between the guide receptacles 112 and the outlet valve plates 116 is a respective outlet valve spring 120 of an outlet valve 99, which is supported on a guide receptacle 112 on the one hand and on an outlet valve plate 116 on the other hand and surrounds an outlet valve stem 118 in the circumferential direction in the region between the outlet valve plate 116 and the guide receptacle 112. This is made clear in particular in FIG. 11.

[0094] An inner groove 122 extending in the longitudinal direction of the guide receptacle 112 is molded into the guide receptacle 112, via which inner groove 122 cleaning liquid can escape from the guide receptacle 112.

[0095] In the region of the valve receptacle 42, the second housing part 16 forms annular second support surfaces 124, which each adjoin an outlet channel 34 in the direction of the valve receptacle 42 and are oriented perpendicularly to the longitudinal axis 43 of the valve receptacle 42. The outlet valve seat bodies 114 are each supported with their end face 126 pointing away from the respective outlet valve seat 106 on a second support surface 124, wherein arranged between the end faces 126 and the second support surfaces 124 is a respective second sealing ring 128, which seals off the respective outlet valve seat body 104 in the axial direction relative to the second housing part 16.

[0096] The guide body 108 is surrounded in the circumferential direction by an annular groove 130, in which a third sealing ring 132 is arranged. The third sealing ring 132 ensures the liquid-tight connection between the second insert part 102 and the guide body 108.

[0097] The annular groove 130 is adjoined in the direction of the housing recess 46 by an annular projection 134 extending over the outer circumference of the guide body 108. At a distance from the annular projection 134, the housing recess 46 forms a radially inwardly directed step 136. A fourth sealing ring 138 is positioned between the annular projection 134 and the step 136, which seals off the guide body 108 in the axial direction relative to the first housing part 14.

[0098] In its region dipping into the housing recess 46, the guide body 108 forms a check valve seat 140 pointing away from the second insert part 120, against which seat a check valve closing body 142 can sealingly abut. In combination with the check valve closing body 142, the check valve seat 140 forms a central check valve 144.

[0099] The outlet valve assembly 100 is configured as a unit that can be preassembled and can be inserted into the valve receptacle 42 and the housing recess 46 during the assembly of the piston pump 10. Since the outlet valve assembly 100 forms all outlet valves 99, this makes the assembly of the piston pump 10 easier.

[0100] As already mentioned, the two housing parts 14 and 16 are configured as metal parts. The two housing parts 14 and 16 may each be configured, e.g., as a die-cast part or as a reshaped part. For example, they may consists of an aluminum or brass material. Here, the provision of the inlet valves 52 and the outlet valves 99 requires no post-processing of the metal parts, because the inlet and outlet valves 52, 99 are inserted in the form of plastic components into the metal parts and comprise the corresponding valve seats. The piston pump 10 can therefore be produced cost-effectively.

[0101] In addition, the piston pump 10 is characterized by good suction characteristics, since the volume of the pump chambers 24 that cannot be displaced by the pistons 26, 28 of the piston pump 10 can be kept very low.