Piston pump for high-pressure cleaning devices

Abstract

The invention relates to a piston pump (10) for a high-pressure cleaning device, having a pump housing (12) with a first housing part (14) and a second housing part (16) each designed as a metal piece. The first housing part (14) is configured with a suction line (20) and a pressure line (22), and the second housing part (16) is configured with a plurality of pump chambers (24) into which reciprocating pistons (26, 28) each dip, and the pump chambers are each in flow connection with the suction line (20) via an inlet channel (32) and with the pressure line (22) via an outlet channel (34). The inlet channel (32) can be closed by an inlet valve (52), and the outlet channel (34) can be closed by an outlet valve (99). The inlet valve (52) has a first insertion part (54) which is inserted into the inlet channel (32), and an inlet closure body (56) which is reciprocally movable relative to the first insertion part. The first insertion part (54) has an inlet valve seat (62) and a guide portion (84) which is arranged offset to the inlet valve seat. The inlet closure body (56) has an inlet valve disc (88) which can be seated in a sealing manner on the inlet valve seat (62), and an inlet valve stem (90) which is coupled to the inlet valve disc and is movably supported on the guide portion (84). In order to improve the piston pump (10) in such a way that the piston pump can be produced inexpensively and has improved suction performance, it is proposed that the first insertion part (54) is made of a plastic material and has an annular inlet valve seat body (60) which faces the pump chambers (24) and which forms the inlet valve seat (62), wherein the guide portion (84) is arranged upstream of the inlet valve seat (62).

Description

TECHNICAL FIELD

[0001] The invention relates to a piston pump for a high-pressure cleaning device for conveying cleaning liquid, having a pump housing with a first housing part and a second housing part, which are each designed as a metal piece, wherein the first housing part is configured with a suction line and a pressure line, and wherein the second housing part is configured with a plurality of pump chambers into which each a reciprocally movable piston is sunk, and the pump chambers are each in flow connection with the suction line via an inlet channel and with the pressure line via 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 has a first insertion part which is inserted into the inlet channel, and an inlet closure body which is movable reciprocally relative to the first insertion part, wherein the first insertion part has an inlet valve seat and a guide portion which is arranged offset to the inlet valve seat, and wherein the inlet closure body has an inlet valve disc which can be seated in a sealing manner on the inlet valve seat, and an inlet valve stem which is coupled with the inlet valve disc, the inlet valve stem being supported in a movable manner on the guide portion. BACKGROUND

[0002] Such a piston pump is known from DE 10 2009 049 095 A1. By means of the piston pump, cleaning liquid, for example water, which is conveyed via the suction line, can be pressurized and fed out via the pressure line. For example, a pressure hose can be coupled with the pressure line, which pressure hose carries a nozzle head on its free end, via which pressurized cleaning liquid can be directed at an object. The piston pump is driven by a drive motor, which is coupled with the pistons of the piston pump, for example via a swash plate transmission, and drives the pistons in a reciprocating linear motion. The reciprocating motion of the pistons sunk into the pump chambers respectively causes a periodic increase and decrease of the pump chamber volume, so that cleaning liquid is sucked into the pump chambers via the inlet channels and pressurized and fed out via the outlet channels. The pressure can be at least 80 bar, for example. In order to be able to withstand the pressure load, the pump housing has a first and a second housing part, which are each designed as a metal piece. The first housing part is configured with the suction line and the pressure line, and the second housing part is configured with the pump chambers and the inlet channels and the outlet channels, via which the pump chambers are each in flow connection with the suction line and the pressure line.

[0003] The inlet channels can be closed by inlet valves, respectively, and the outlet channels can be closed by outlet valves, respectively. Inlet valves as proposed in DE 10 2009 049 095 A1 have a seating part and an inlet closure body which is displaceable relative to the seating part, respectively. The seating part is configured with an inlet valve seat and a guide portion which is arranged offset to the inlet valve seat in the direction of the associated pump chamber. The inlet closure body has an inlet valve disc which can be seated in a sealing manner on the inlet valve seat and an inlet valve stem which is coupled to the inlet valve disc in the direction of the associated pump chamber, the inlet valve stem being supported in a movable manner on the guide portion. The seating part is usually made of stainless steel and is pressed into the inlet channel or is held in the inlet channel in a rotationally fixed and axially immovable manner by a flange. This is associated with non-negligible manufacturing costs.

[0004] In the piston pump known from DE 10 2009 049 095 A1, the guide portion and the inlet valve stem which is held in a movable manner on the guide portion are arranged downstream of the inlet valve seat relative to the flow direction of the cleaning liquid. This increases the pump chamber volume which cannot be pushed by the piston when the piston is moved in the direction of the inlet valve seat, the so-called dead volume. This in turn adversely affects the suction performance of the piston pump.

[0005] Piston pumps for high-pressure cleaning devices are known from WO 2008 / 086950 A1 and EP 2 805 050 B1, in which two housing parts of the pump housing are made of a plastic material. This allows the inlet valve seat to be formed directly into the housing part, which is also configured with a guide portion for the inlet closure body, wherein the guide portion is arranged upstream of the inlet valve seat. However, a pump housing made of a plastic material has a lower pressure resistance than a pump housing formed from a metal piece. SUMMARY

[0006] The task of the present invention is to improve a piston pump of the type mentioned at the outset, so that the piston pump can be produced more inexpensively and has an improved suction performance.

[0007] This task is solved according to the invention in a piston pump of the type mentioned at the outset in that a first seating part is made of a plastic material and has an annular inlet valve seat body which faces the pump chamber, the inlet valve seat body forming an inlet valve seat, wherein the guide portion is arranged upstream of the inlet valve seat relative to the flow direction of the cleaning liquid.

[0008] The pump housing of the piston pump according to the application has two housing parts, which are each designed as a metal piece and thus have a very high compressive strength. The second housing part is configured with an inlet channel, into which a first insert part made of a plastic material is each inserted. The first insert part has an annular inlet valve seat body, which faces the associated pump chamber and constitutes an inlet valve seat. Upstream of the inlet valve seat body with respect to the flow direction of the cleaning fluid, i.e. in the direction of the suction line, the first insert part is configured with a guide portion, on which the inlet valve seat body is supported in a movable manner. The first insert part made of plastic allows the inlet valve seat to be provided in an inexpensive manner without the second housing part made of metal having to be subjected to an elaborate reworking. Since the first insert part is made of plastic, the manufacturing costs of the first insert part are comparatively low. The first insert part can be inserted into the inlet channel from the side of the inlet channel facing the associated pump chamber, so that the guide portion constituted by the first insert part occupies a position upstream of the inlet valve seat. This makes it possible to keep the volume that cannot be pushed by the piston, the so-called dead space, very low. The piston pump according to the application is therefore characterized by comparatively low manufacturing costs and improved suction performance.

[0009] The first housing part and / or the second housing part is preferably designed as a die casting or a reshaped piece.

[0010] Preferably, the first housing part and / or the second housing part is made of aluminum or brass material.

[0011] Advantageously, the inlet valve seat body projects from the inlet channel in the direction of the pump chamber.

[0012] Advantageously, the second housing part is configured with an annular first support surface which is coupled to the inlet channel in the direction of the pump chamber, which first support surface is oriented perpendicular to the longitudinal axis of the inlet channel and on which the inlet valve seat body rests with a resting surface. In this design, the inlet valve seat body is supported by the first support surface of the second housing part.

[0013] Preferably, the inlet valve seat body has a seal ring receptacle coupled with the abutment face, in which a seal ring is arranged which seals the first support face relative to the inlet valve seat body in the axial direction. The seal ring arranged between the inlet valve seat body and the first support face of the second housing part constitutes a seal in the axial direction with respect to the longitudinal axis of the inlet channel. This has the advantage that possible lines which can occur when manufacturing the second housing part, which are oriented parallel to the longitudinal axis of the inlet channel and which can occur when the second housing part is manufactured, do not impair the sealing effect of the seal ring. In particular when the second housing part is designed as a die casting, such lines can occur when the second housing part is manufactured by performing a demolding. The possible lines which occur when demolding extend in the demolding direction, that is to say these lines extend parallel to the longitudinal axis of the inlet channel, but not parallel to the first support face, since this is oriented perpendicularly to the longitudinal axis of the inlet channel. Thus, the lines which occur when the second housing part is demolded do not impair the seal in the axial direction.

[0014] In an advantageous embodiment of the piston pump according to the application, the seal ring receptacle is configured with an annular groove which surrounds the inlet valve seat body in the peripheral direction, the annular groove having a first groove wall coupled with the abutment face, a second groove wall being coupled with the first groove wall, wherein the outer diameter of the inlet valve seat body increases the further it is from the second groove wall and the closer it is to the abutment face. The outer diameter which increases in the direction of the abutment face reduces the risk of the seal ring which is inserted into the seal ring receptacle unintentionally coming loose from the seal ring receptacle when the first insertion part is fitted. Furthermore, the abutment face can be designed relatively large.

[0015] The first groove wall can be designed, for example, in the type of a cone, wherein the cone angle is preferably approximately 10° to approximately 30°, preferably approximately 15° to approximately 25°, in particular approximately 20°.

[0016] Advantageously, the outer diameter of the inlet valve seat body increases via the second groove wall the further it is from the abutment face. In this design, the seal ring receptacle is designed in the type of a circumferential groove into which the seal ring can be inserted without the risk of the seal ring coming loose from the seal ring receptacle when the first insertion part is inserted into the inlet channel.

[0017] Advantageously, the first insertion part is held relative-rotationally and axially immovably with respect to the inlet channel.

[0018] It can be provided, for example, that the first insertion part can be latched with the second housing part.

[0019] In a preferred embodiment of the application, the first insertion part has at least one holding arm which is coupled to the inlet valve seat body in the direction of the suction line and held against relative rotation with respect to the inlet channel. In this embodiment, the first insertion part has at least one holding arm upstream of the inlet valve seat body. By means of the holding arm, the first insertion part can be fastened in a simple manner on the inlet channel. The at least one holding arm is here sunk into the inlet channel.

[0020] Preferably, the at least one holding arm penetrates the inlet channel.

[0021] It is particularly advantageous if the at least one holding arm engages from behind the inlet channel on the side of the inlet channel facing the suction line. Thereby it can be ensured that, after the first insertion part has been inserted into the inlet channel from the side facing the associated pump chamber so that the at least one holding arm engages from behind the inlet channel on the side facing away from the pump chamber, the first insertion part can then no longer be easily removed from the inlet channel.

[0022] In a preferred embodiment of the application, the at least one holding arm is connected to the inlet valve seat body in a material-locking manner. In this embodiment, the at least one first holding arm forms, together with the inlet valve seat body, a one-piece plastic forming.

[0023] Preferably, the first insertion part has two holding arms which are diametrically opposite each other with respect to the longitudinal axis of the inlet channel, which allow the first insertion part to be designed mirror-symmetrically and thus to be able to withstand high loads.

[0024] As already mentioned, the inlet closure body has an inlet valve stem which is movably supported on a guide of the first insertion part. Advantageously, the guide is fastened on the at least one holding arm.

[0025] Preferably, the guide is connected to the at least one holding arm in a material-locking manner. In this embodiment, the guide forms, together with the at least one holding arm and preferably together with the inlet valve seat body, a one-piece plastic forming.

[0026] Advantageously, the at least one holding arm has an end section facing away from the inlet valve seat body, which is sunk into a recess of the second housing part.

[0027] It can be provided in particular that the end section of the at least one holding arm forms a form-locking with the recess of the second housing part. This enables the fastening of the first insertion part against relative rotation on the second housing part in a simple manner.

[0028] It is particularly advantageous if the end section of the at least one retaining arm is heat deformable. This allows the at least one retaining arm to be deformed by means of heat loading in a simple manner after it has been introduced into the inlet channel from the side facing the associated pump chamber. To this end, the at least one retaining arm can be composed of a plastic material which is heat deformable.

[0029] The at least one retaining arm can be designed, for example, straight before it is introduced into the inlet channel and can be heat deformed into a curved or angular shape after it has been introduced into the inlet channel.

[0030] It can be provided, for example, that the end section of the at least one retaining arm which is remote from the inlet valve seat body is heat deformed radially outwards after the retaining arm has been introduced into the inlet channel, so that the end section points outwards after the heat deformation with respect to the longitudinal axis of the inlet channel and engages behind the inlet channel on the side remote from the pump chamber.

[0031] It is advantageous if the first introduction portion constitutes a one-piece plastic forming in its entirety.

[0032] Preferably, the first introduction portion is composed of a POM material (polyoxymethylene material).

[0033] The inlet closure body has an inlet valve disc and an inlet valve stem which is coupled to the inlet valve disc on the side remote from the pump chamber. The inlet valve disc can be placed against the inlet valve seat of the first introduction portion in a sealing manner, and the inlet valve stem is supported in a movable manner on the guide portion of the first introduction portion. Preferably, the inlet valve disc is connected to the inlet valve stem in a material-locking manner.

[0034] The guide portion is preferably designed in an annular manner.

[0035] It is advantageous if the inlet valve stem passes through the guide portion and has a stem section which projects out of the guide portion in the direction of the suction line, on which stem section a spring holder is fastened, wherein the inlet valve spring is clamped between the spring holder and the guide portion. By means of the inlet valve spring which is supported on the spring holder on the one hand and on the guide portion on the other hand, the inlet valve stem is loaded with a spring force and with this inlet valve stem also the inlet valve disc is loaded with a spring force, against which spring force the inlet valve disc is pressed against the inlet valve seat. In a suction movement of the piston which dips into the pump chamber, the inlet valve disc can be lifted from the inlet valve seat against the action of the inlet valve spring, so that cleaning liquid can flow from the suction line into the pump chamber via the inlet valve. If the piston carries out a push movement which points in the opposite direction, the inlet valve disc is pressed by the inlet valve spring against the inlet valve seat, so that cleaning liquid cannot flow back into the suction line via the inlet valve.

[0036] In an advantageous design of the application, the guide is configured with a stop which limits the movement of the inlet valve stem in the direction of the pump chamber and thus also the movement of the inlet valve disc in the direction of the pump chamber. When the inlet valve stem is moved in the direction of the pump chamber, the spring retainer fastened to the inlet valve stem comes closer and closer to the guide and finally comes into abutment with the stop of the guide, thereby preventing further movement of the inlet valve stem in the direction of the pump chamber and thus also preventing further lifting of the inlet valve disc from the inlet valve seat.

[0037] In an advantageous design, the manufacturing costs of the piston pump according to the application are further reduced by the second housing part having a valve receptacle into which the outlet channel opens and by the piston pump having an outlet valve structure assembly which constitutes all of the outlet valves, wherein the outlet valve structure assembly has a second insert part which is made of a plastic material and is inserted into the valve receptacle and which has a plurality of annular outlet valve seat bodies which each constitute an outlet valve seat. In this design, the second housing part which is configured as a metal piece has the valve receptacle. The second insert part of the outlet valve structure assembly is inserted into the valve receptacle. The second insert part is made of a plastic material and has a plurality of annular outlet valve seat bodies which each constitute an outlet valve seat, in particular oriented in alignment with the outlet channel. Thus, the outlet valve seats are provided by the second insert part, so that the costly reworking of the second housing part which is designed as a metal piece can be dispensed with. Here, only one second insert part is used which has all of the outlet valve seats of the piston pump according to the application. This facilitates the assembly of the piston pump.

[0038] Preferably, the valve receptacle is arranged on the side of the second housing part which faces the first housing part.

[0039] The outlet valve structure assembly is advantageously designed as a preassemblable structural unit. This allows the outlet valve structure assembly which constitutes all of the outlet valves to be assembled even before the entire piston pump is assembled as a structural unit which can be handled independently. The outlet valve structure assembly can be assembled at a first assembly site and then transported to a second assembly site where the entire piston pump is assembled.

[0040] In a preferred embodiment of the application, the second housing part is configured with a plurality of annular second support surfaces in the region of the valve receptacle, which are oriented perpendicular to the longitudinal axis of the valve receptacle and are respectively coupled to the outlet channel in the flow direction of the cleaning liquid and on which the outlet valve seat bodies respectively abut with a sealing ring in between. The perpendicular orientation of the second support surfaces allows the sealing ring abutting on the second support surfaces to be designed as an axial seal, so that linear marks which can occur in the region of the valve receptacle when manufacturing the second housing part and which are oriented parallel to the longitudinal axis of the valve receptacle do not impair the sealing effect of the sealing ring. Such linear marks can occur in particular when the second housing part is designed as a die casting, when demoulding is performed in the manufacture thereof. The possible linear marks which occur in the region of the valve receptacle when demoulding all extend in the demoulding direction, that is to say they extend parallel to the longitudinal axis of the valve receptacle, but not parallel to the second support surfaces, since these are oriented perpendicular to the longitudinal axis of the valve receptacle. Thus, the possible linear marks which occur in the region of the valve receptacle when demoulding the second housing part do not impair the sealing which acts in the axial direction.

[0041] Preferably, the second support surfaces are respectively coupled to the outlet channel in the flow direction of the cleaning liquid.

[0042] Advantageously, the outlet valves respectively have an outlet closure body which is reciprocally movable relative to the second insertion part, the outlet closure body having an outlet valve disc which can be seated in a sealing manner onto the outlet valve seat and an outlet valve stem which is coupled to the outlet valve disc in a direction away from the outlet channel. The outlet valve stem is arranged downstream of the outlet valve seat relative to the flow direction of the cleaning liquid. This leads to a further reduction of the dead space of the associated pump chamber and thus to an improved suction performance of the piston pump.

[0043] Preferably, the outlet valve arrangement has a guide body which is made of a plastic material and has a plurality of guide elements on which the outlet valve stems are respectively supported in a movable manner. In such an embodiment, all outlet valve stems are guided by means of the guide body. This leads to a further simplification of the assembly of the piston pump.

[0044] The guide body has a plurality of guide elements which respectively guide the outlet valve stem of the outlet closure body. In a preferred embodiment of the application, the guide elements are respectively configured with a guide receptacle into which the outlet valve stem sinks.

[0045] Advantageously, the guide receptacles respectively have at least one inner groove which extends in the longitudinal direction of the guide receptacle. The cleaning liquid can escape from the respective guide receptacle via the inner groove.

[0046] Advantageously, the outlet valve spring is clamped between the guide element and the outlet valve disc. The outlet valve spring allows the outlet valve disc to be preloaded toward its corresponding outlet valve seat.

[0047] In an advantageous embodiment of the invention, the guide body can be releasably and fluid-tightly connected to the second insertion portion. This allows the outlet valve structural assembly to be designed as a pre-assembled structural unit in a particularly simple manner. For this purpose, in a first assembly step, the outlet valve stem can be inserted into the guide receiving portion of the guide body, wherein the outlet valve stem is surrounded by an outlet valve spring in the area extending from the guide receiving portion, the outlet valve spring being supported on both the guide receiving portion and the outlet valve disc. Subsequently, the guide body can be fluid-tightly connected to the second insertion portion, preferably with a sealing ring present. In a subsequent assembly step, the second insertion portion connected to the guide body can be inserted into the valve receiving portion of the second housing portion. The two housing portions of the pump housing can then be joined together.

[0048] Preferably, the guide body can be connected to the second insertion portion in a plug-like manner. For example, it can be configured such that the guide body can be inserted into the second insertion portion with at least one sealing ring present in the middle.

[0049] A particularly advantageous feature is that the guide body is configured with a check valve seat for a centrally located check valve downstream of the outlet valve. In this design, the second insert constitutes the valve seat of the outlet valve, while the guide body constitutes the valve seat of the central check valve. This further simplifies the assembly of the piston pump. The check valve closing body can occupy a position immediately downstream of the check valve seat formed by the guide body and can be preloaded towards the check valve seat by a check valve spring.

[0050] The central check valve is preferably located in the pressure line.

[0051] It can be configured such that the first housing portion has a housing recess aligned with the valve receiving portion of the second housing portion, and with at least one sealing ring present in between, the guide body is recessed into the housing recess. In this design, the outlet valve structure assembly occupies a position between the first and second housing portions, wherein the first housing portion has a housing recess on its side facing the second housing portion, the guide body is recessed into the housing recess, and wherein the second housing portion has a valve receiving portion on its side facing the first housing portion, aligned with the housing recess, into which the second insertion portion is inserted. The guide body is fluid-tightly connected to the first housing portion, and the second insertion portion is fluid-tightly connected to the second housing portion, and furthermore, the guide body and the second insertion portion are fluid-tightly connected to each other.

[0052] The pressure line is advantageously coupled with the outlet valve arrangement assembly in the flow direction of the cleaning liquid.

[0053] It is advantageous if at least one sealing ring arranged between the guide body and the housing recess of the first housing part encloses the guide body in peripheral direction.

[0054] It is particularly advantageous if the guide body has an outwardly protruding annular projection, to which an annular projection is assigned a step pointing radially inwards with respect to the longitudinal axis of the housing recess, wherein a sealing ring is arranged between the annular projection and the step. The cover sealing ring can constitute an axial seal, so that a line mark which can occur in the region of the housing recess during the manufacture of the first housing part and which is oriented parallel to the longitudinal axis of the housing recess does not impair the sealing effect of the sealing ring. Such line marks occur in particular when the first housing part is designed as a die casting, in which case they occur during the ejection during the manufacture. The possible line marks which occur in the region of the housing recess during the ejection extend in the ejection direction, i.e. they extend parallel to the longitudinal axis of the housing recess, but not parallel to the radially inwards pointing step. Thus, the possible line marks which occur in the region of the housing recess during the ejection of the first housing part do not impair the sealing which acts in axial direction. BRIEF DESCRIPTION OF DRAWINGS

[0055] The following description of preferred embodiments of the application serves for a detailed explanation in conjunction with the drawings.

[0056] wherein:

[0057] Figure 1 : shows a sectional view of a piston pump;

[0058] Figure 2 : shows a sectional view of a piston pump; Figure 1 : shows a sectional view of a piston pump;

[0059] Figure 3 : shows a sectional view of a piston pump; Figure 2 : shows an enlarged sectional view of detail X of

[0060] Figure 4 : shows a perspective view of a second housing part of a piston pump;

[0061] Figure 5 : shows an enlarged sectional view of detail Y of Figure 2 : shows an enlarged sectional view of detail Y of

[0062] Figure 6 : shows a sectional view of the inlet valve of Figure 5 : shows a sectional view of the inlet valve of

[0063] Figure 7 : shows a sectional view of the inlet valve of Figure 5perspective view of the first insertion portion of the inlet valve before assembly;

[0064] Figure 8 : shows Figure 7 : shows a cross-sectional view of the first insertion portion of the inlet valve;

[0065] Figure 9 : shows a perspective view of the first insertion portion of the inlet valve after assembly;

[0066] Figure 10 : shows Figure 9 : shows a cross-sectional view of the first insertion portion of the inlet valve;

[0067] Figure 11 : shows Figure 3 : shows a cross-sectional view of the outlet valve structure assembly. DETAILED DESCRIPTION

[0068] An advantageous embodiment of a piston pump for a high-pressure cleaning device according to the application is shown schematically in the figures and is designated as a whole by the reference numeral 10. By means of the piston pump 1, cleaning fluid, preferably water, can be conveyed. The piston pump 10 comprises a pump housing 12 having a first housing part 14 and a second housing part 16. Both housing parts 14, 16 are designed as metal parts. In the embodiment shown, they are each designed in the form of a die-cast aluminum part.

[0069] The first housing part 14 delimits a front side 18 of the piston pump 10 and is configured with a suction line 20 and a pressure line 22. The second housing part 16 is configured with three pump chambers, into each of which a piston is sunk. For the sake of a better overview, only the pump chamber 24 and two pistons 26, 28 are shown in the figures. All pistons are moved in an oscillating manner into the respective pump chamber 24 by means of a swash plate known per se, which is not shown in the figures, and are moved out of the pump chamber again by means of a helical spring 30 surrounding the respective piston, so that the volume of the pump chamber 24 is periodically changed.

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

[0071] On the side facing the suction line 20, two recesses 36, 38 of the second housing part 16, which are diametrically opposite one another, are respectively coupled to the inlet channels 32. This is particularly clear from Figure 4 In the direction of the pump chamber 24, an annular first support face 40 is respectively coupled to the inlet channels 34, which first support face is formed by the second housing part 16 and faces the respective pump chamber 24. This is particularly clear from Figure 2 andFigure 5 It is clearly visible that the first support surface is oriented perpendicular to the longitudinal axis 33.

[0072] The cleaning liquid to be pressurized can be sucked into the respective pump chamber 24 via the inlet channel 32, and the cleaning liquid can be delivered from the pump chamber 24 via the outlet channel 34. The outlet channel 34 opens into a central valve accommodation 42 of the second housing part 16, which is delimited in the peripheral direction by a cylindrical wall 44. The valve accommodation 42 is arranged on the side of the second housing part 16 facing the first housing part 14 and has a longitudinal axis 43 which is oriented parallel to the longitudinal axis 33 of the inlet channel 32.

[0073] The first housing part 14 has a housing recess 46 on its side facing the second housing part 16, which is oriented in register with the valve accommodation 42 of the second housing part 16, and the pressure line 22 is coupled with the housing recess in the direction of the front side 18 of the first housing part 14.

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

[0075] The inlet channels 32 can each be closed by an inlet valve 52. These inlet valves 52 are identical in design and each have a first insert part 54 which is formed from a plastics material, preferably from a POM material, and which is inserted into the inlet channel 32. In addition, the inlet valves 52 each have an inlet closure body 56 which can be moved reciprocatingly in the axial direction relative to the first insert part 54.

[0076] The first insert part 54 has 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 projects into the respective assigned pump chamber 24 and is supported on the first support surface 40 which is coupled with the respective inlet channel 32 in the direction of the pump chamber 24 with a bearing surface 64 facing away from the respective pump chamber 24.

[0077] Coupled with the bearing surface 64 is a sealing ring accommodation 66 in the form of an annular groove 68 which extends on the periphery of the inlet valve seat body 60 and has a first groove wall 70 which is coupled directly with the bearing surface 64 and a second groove wall 72 which is coupled with the first groove wall. Via the first groove wall 70, the outer diameter of the inlet valve seat body 60 is constantly reduced as the distance from the bearing surface 64 increases, while via the second groove wall 72, the outer diameter of the inlet valve seat body 60 is constantly increased as the distance from the bearing surface 64 increases. This is particularly evident from the cross-sectional view in Fig. 2. Figure 7 andFigure 9 It is clear to see.

[0078] The seal ring receptacle 66 accommodates a first seal ring 74, which seals the inlet valve seat body 60 in relation to the first support face 40 in the axial direction.

[0079] In the direction of the suction line 20, two diametrically opposite retaining arms 76, 78 in relation to the longitudinal axis 33 of the inlet channel 32 are coupled to the inlet valve seat body 60 of the first insert part 54, pass through the inlet channel 34 and have end sections 80, 82, respectively, which project away from the inlet valve seat body 60 on the side of the inlet channel 32 facing away from the pump chamber 24 and, in the assembled state of the inlet valve 52, engage behind the respective inlet channel 32 in such a way that the end sections sink into the recesses 36, 38 of the second housing part 16 and form a form-fit therewith. This will be explained in detail below.

[0080] The retaining arms 76, 78 accommodate an annular guide 84 between them in the region of the inlet channel 32. The guide 84 has an outer diameter which is smaller than the diameter of the inlet channel 32, which allows the cleaning liquid to flow around the guide 84 inside the inlet channel 32.

[0081] The guide 84 is connected to the retaining arms 76, 78 in a material-locking manner and the retaining arms 76, 78 are connected to the inlet valve seat body 60 in a material-locking manner.

[0082] In the illustrated embodiment, the first insert part 54 constitutes a one-piece plastic formed part which defines the inlet valve seat body 60, the retaining arms 76, 78 and the guide 84.

[0083] The inlet closure body 56 comprises an inlet valve disc 88 and an inlet valve stem 90 which is coupled to the inlet valve disc 88 in one piece on the side of the inlet valve disc 88 facing away from the pump chamber 24. The inlet valve disc 88 can be seated in a sealing manner on the inlet valve seat 62 of the inlet valve seat body 60 and the inlet valve stem 90 extends through the guide 84 in the direction of the suction line 20.

[0084] A spring holder 94 is fastened on a stem section 92 of the inlet valve stem 90 which projects away from the guide 84 in the direction of the suction line 20. An inlet valve spring 96 is clamped between the spring holder 94 and the guide 84. The inlet valve spring 96 is designed as a coil spring which is supported on the spring holder 94 on the one hand and on the guide 84 on the other hand and surrounds the inlet valve stem 90 in the peripheral direction in the region between the guide 84 and the spring holder 94. The inlet valve disc 88 which is connected in one piece to the inlet valve stem 90 is pressed by the inlet valve spring 96 against the inlet valve seat 62 of the inlet valve seat body 60, so that the inlet valve 52 assumes its closed position.

[0085] If the pistons 26, 28 sunk into the respective pump chamber 24 are moved in the direction away from the inlet channel 32, the inlet valve 52 is opened by the inlet valve disc 88 being lifted from the inlet valve seat 62 against the spring force of the inlet valve spring 96 and thereby releasing the flow connection from the suction line 20 to the pump chamber 24, so that cleaning liquid can flow from the suction line 20 into the pump chamber 24 via the inlet channel 32. The cleaning liquid can flow here from the outside around the spring retainer 94, the inlet valve spring 96 and the guide 84, so that the flow losses can be kept low.

[0086] The inlet valve disc 88 can be lifted from the inlet valve seat 62 until the spring retainer 94 comes to rest against the stop 98 of the type of a press projection or sleeve of the guide 84. The stop 98 thus limits the linear movement of the inlet valve disc 96.

[0087] If the pistons 26, 28 are moved in the direction of the inlet channel 32, the inlet valve disc 88 occupies its position on the inlet valve seat, so that cleaning liquid cannot flow back into the suction line 20.

[0088] For the assembly of the inlet valve 52, in a first assembly step, as shown in Figure 7 and Figure 8 , the first insertion part 54 can be inserted into the inlet channel 32 from the side facing the pump chamber 24 with initially linearly oriented retaining arms 76, 78, so that the abutment face 64 comes into contact with the first support face 40 and the end sections 80, 82 of the retaining arms 76, 78 project out of the inlet channel 32 on the side facing away from the pump chamber 24. Subsequently, the end sections 80, 82 can be thermally deformed, wherein the end sections 80, 82 are pressed radially outwards and sink into the recesses 36, 38 and form a form-fit with the recesses, respectively. This results in the first insertion part 54 being axially immovable and held against relative rotation on the inlet channel 32. In a further assembly step, the inlet closure 56 can then be assembled on the first insertion part 54 by inserting the inlet valve rod 90 into the first insertion part 54 from the side facing the pump chamber 24, wherein the inlet valve rod 90 passes through the guide 84. The inlet valve spring 96 can then be placed on the rod section 92 projecting out of the guide 84 on the side facing away from the pump chamber 24 and subsequently the spring retainer 94 can be fastened on the rod section 92. The spring retainer 94 can be fastened on the rod section 92, for example, by means of ultrasonic welding.

[0089] The outlet channels 34 leading into the valve receptacles can each be closed by an outlet valve 99. The outlet valves 99 are designed identically and are formed by an outlet valve arrangement 100 which can be preassembled and 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 arrangement 100 is shown enlarged in Figure 3 and Figure 11 . It comprises a second insert part 102 which is formed from a plastic material, for example from a POM material. The second insert part 102 is inserted into the valve receptacle 52 and has a plurality of annular outlet valve seat bodies 104 which each form an outlet valve seat 106 of an outlet valve 99.

[0091] In addition to the second insert part 102, the outlet valve arrangement 100 has a guide body 108 which is likewise formed from a plastic material, for example from a fibre-reinforced plastic material, and which is connected to the second insert part 102 in a releasable and fluid-tight manner. The guide body 108 is configured with guide elements 110 in the form of guide receptacles 112 which are each 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 closure bodies 114 which are movable reciprocatingly relative to the second insert part 102 and the guide body 108 and each have an outlet valve disc 116 of an outlet valve 99 and an outlet valve stem 118 which is integrally coupled with the outlet valve disc. The outlet valve disc 116 can be seated in a sealing manner on the outlet valve seat 106 and the outlet valve stem 118 which is coupled with the outlet valve disc on the side of the outlet valve disc which is remote from the outlet valve seat 106 sinks into the guide receptacle 112 in which the outlet valve stem is movably supported.

[0093] An outlet valve spring 120 of the outlet valve 99 is clamped between the guide receptacle 112 and the outlet valve disc 116, which outlet valve spring is supported on the guide receptacle 112 and on the outlet valve disc 116 and surrounds the outlet valve stem 118 in the peripheral direction in the region between the outlet valve disc 116 and the guide receptacle 112. This is clearly seen in particular from Figure 11 .

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

[0095] In the region of the valve accommodation 42, the second housing part 16 is configured with annular second support faces 124 which are respectively coupled to the outlet channels 34 in the direction of the valve accommodation 42 and are oriented perpendicular to the longitudinal axis 43 of the valve accommodation 42. The outlet valve seat bodies 114 are respectively supported on the second support faces 124 with their end sides facing away from the respective outlet valve seat 16, wherein a second sealing ring 128 is respectively arranged between the end side 126 and the second support face 124, which seals the respective outlet valve seat body 104 in the axial direction with respect to the second housing part 16.

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

[0097] In the direction of the housing recess 46, the annular groove 130 is coupled to an annular protrusion 134 which extends over the outer periphery of the guide body 108. Spaced apart from the annular protrusion 134, the housing recess 46 is configured with a step 136 which points radially inwards. A fourth sealing ring 138 is positioned between the annular protrusion 134 and the step 136, which seals the guide body 108 in the axial direction with respect to the first housing part 14.

[0098] The guide body 108 is configured in the region in which it sinks into the housing recess 46 with a check valve seat 140 facing away from the second insertion part 102, against which a check closure body 142 can be seated in a sealing manner. The check valve seat 140 and the check closure body 142 in combination constitute a central check valve 144.

[0099] The outlet valve structure assembly 100 is designed as a preassembled structural unit and can be inserted into the valve accommodation 42 and the housing recess 46 in the assembled state of the piston pump 10. Since the outlet valve structure assembly 100 constitutes all of the outlet valves 99, this facilitates the assembly of the piston pump 10.

[0100] As already mentioned, the two housing parts 14 and 16 are designed as metal pieces. The two housing parts 14 and 16 can be designed, for example, as die cast parts or reshaped parts, respectively. They can be made, for example, of aluminum or brass material. The provision of the inlet valves 52 and the outlet valves 99 does not require subsequent processing of the metal pieces here, since the inlet valves and the outlet valves 52, 99 are inserted into the metal pieces in the form of plastic pieces and have the respective valve seats. Thus, the piston pump 10 can be produced inexpensively.

[0101] Furthermore, the piston pump 10 is characterized by good suction performance, since the volume of the pump chamber 24 which cannot be pushed by the pistons 26, 28 of the piston pump 10 can be kept very low.

Claims

1. Piston pump for conveying cleaning liquid of a high-pressure cleaning device, having a pump housing (12) with a first housing part (14) and a second housing part (16) each designed as a metal piece, wherein The first housing part (14) is configured with a suction line (20) and a pressure line (22), and wherein the second housing part (16) is configured with a plurality of pump chambers (24) into which reciprocably movable pistons (26, 28) are respectively sunk, and the pump chambers are respectively in flow connection with the suction line (20) via an inlet channel (32) and with the pressure line (22) via an outlet channel (34), wherein the inlet channel (32) can be closed by an inlet valve (52), and the outlet channel (34) can be closed by an outlet valve (99), wherein the inlet valve (52) has a first inserted part (54) which is inserted into the inlet channel (32) and an inlet closure body (56) which is reciprocally movable relative to the first inserted part (54), wherein the first inserted part (54) has an inlet valve seat (62) and a guide portion (84) which is arranged offset to the inlet valve seat (62), and wherein the inlet closure body (56) has an inlet valve disc (88) which can be seated on the inlet valve seat (62) in a sealing manner and an inlet valve stem (90) which is coupled with the inlet valve disc (88), the inlet valve stem being movably supported on the guide portion (84), characterized in that the first inserted part (54) is made of a plastic material and has an annular inlet valve seat body (60) which faces the pump chambers (24), the inlet valve seat body forming the inlet valve seat (62), wherein the guide portion (84) is arranged upstream of the inlet valve seat (62) relative to the flow direction of the cleaning liquid.

2. The piston pump of claim 1, wherein The inlet valve seat body (60) projects out of the inlet channel (32) in the direction of the pump chambers (24).

3. The piston pump of claim 2, wherein, The second housing part (16) is configured with an annular first support face (40) which is coupled with the inlet channel (32) in the direction of the pump chambers (24), the first support face being oriented perpendicular to a longitudinal axis (33) of the inlet channel (32), and the inlet valve seat body (60) is seated against the first support face with a seating face (64).

4. The piston pump of claim 3, wherein The inlet valve seat body (60) has a sealing ring receptacle (66) which is coupled with the seating face (64), in which a sealing ring (74) is arranged which seals the inlet valve seat body (60) relative to the first support face.

5. The piston pump of claim 4, wherein, The sealing ring receptacle (66) is formed as an annular groove (68) which circumferentially surrounds the inlet valve seat body (60), the annular groove having a first groove wall (70) which is coupled with the seating face (64), and a second groove wall (72) which is coupled with the first groove wall, wherein an outer diameter of the inlet valve seat body (60) increases as it gets closer and closer to the seating face (64) starting from the second groove wall.

6. The piston pump of claim 5, wherein, On the second groove wall (72), the outer diameter of the inlet valve seat body (60) increases as the distance to the seating face (64) increases.

7. The piston pump of claim 1, wherein, The first insertion portion (54) has at least one retaining arm (76, 78) which is coupled to the inlet valve seat body (60) in the direction of the suction line (20) and is held against relative rotation with respect to the inlet channel (32).

8. The piston pump of claim 7, wherein, The at least one retaining arm (76, 78) counter-clamps the inlet channel (32) on its side facing the suction line (20).

9. The piston pump of claim 7, wherein, The at least one retaining arm (76, 78) is connected to the inlet valve seat body (60) in a material-locking manner.

10. The piston pump of claim 7, wherein, The first insertion portion (54) has two retaining arms (76, 78) which are diametrically opposite with respect to the longitudinal axis (33) of the inlet channel (32).

11. The piston pump of claim 7, wherein, The guide portion (84) is fixed on the at least one retaining arm (76, 78).

12. The piston pump of claim 7, wherein, The guide portion (84) is connected to the at least one retaining arm (76, 78) in a material-locking manner.

13. The piston pump of claim 7, 8, 9, 10, 11 or 12, wherein, The at least one retaining arm (76, 78) has an end section (80, 82) which faces away from the inlet valve seat body (60) and which is sunk into a recess (36, 38) of the second housing portion (16).

14. The piston pump of claim 13, wherein, The end section (80, 82) of the at least one retaining arm (76, 78) is form-locked with the recess (36, 38).

15. The piston pump of claim 13, wherein, The end section (80, 82) of the at least one retaining arm (76, 78) is heat-deformable.

16. The piston pump of claim 1, wherein, The first insertion portion (54) is a one-piece plastic formed part.

17. The piston pump of claim 1, wherein, The inlet valve stem (90) passes through the guide portion (84) and has a stem section (92) which projects out of the guide portion (84) in the direction of the suction line (20), on which a spring holder (94) is fastened, wherein an inlet valve spring (96) is clamped between the spring holder (94) and the guide portion (84).

18. The piston pump of claim 17, wherein, The guide portion (84) is configured with a stop which limits the movement of the inlet valve disc (88) in the direction of the pump chamber (24).

19. The piston pump of claim 1, wherein, The second housing portion (16) has a valve receptacle (42) into which the outlet channel (34) opens, and the piston pump (10) has an outlet valve structure assembly (100) which constitutes all outlet valves (99), wherein the outlet valve structure assembly (100) has a second insertion portion (102) which is made of a plastic material and is inserted into the valve receptacle (42), and the second insertion portion has a plurality of annular outlet valve seat bodies (104) which each constitute an outlet valve seat (106).

20. The piston pump of claim 19, wherein, The outlet valve structure assembly (100) is designed as a pre-assembled structural unit.

21. The piston pump of claim 19, wherein, The second housing part (16) is configured with a plurality of annular second support faces (124) in the region of the valve receptacle (42), which are oriented perpendicular to the longitudinal axis (43) of the valve receptacle (42) and are respectively coupled to the outlet channel (34) in the flow direction of the cleaning liquid and respectively have an outlet valve seat body (104) resting on the second support face with an intermediate sealing ring.

22. The piston pump of claim 19, wherein, The outlet valve (99) respectively has an outlet closure body (114) which is displaceable relative to the second insertion part (102), which has an outlet valve disc (116) which can be seated on the outlet valve seat (106) in a sealing manner and an outlet valve stem (118) which is coupled to the outlet valve disc (116) in a direction away from the outlet channel (34).

23. The piston pump of claim 22, wherein, The outlet valve arrangement (100) has a guide body (108) which is made of a plastic material and has a plurality of guide elements (110) on which the outlet valve stem (118) is respectively supported in a displaceable manner.

24. The piston pump of claim 23, wherein, The guide elements (110) are respectively configured with a guide receptacle (112) into which the outlet valve stem (118) is sunk.

25. The piston pump of claim 24, wherein, The guide receptacles (112) respectively have at least one inner groove (122) which extends in the longitudinal direction of the guide receptacle (112).

26. The piston pump of claim 23, wherein, Outlet valve springs (120) are respectively clamped between the guide elements (110) and the outlet valve disc (116).

27. The piston pump of claim 23, wherein, The guide body (108) can be connected to the second insertion part (102) in a releasable and fluid-tight manner.

28. The piston pump of claim 23, wherein, The guide body (108) is configured with a check valve seat (140) for a centrally arranged check valve (144) downstream of the outlet valve (99) relative to the flow direction of the cleaning liquid.

29. The piston pump of claim 23, wherein, The first housing part (14) has a housing recess (46) which is oriented in alignment with the valve receptacle (42), into which the guide body (108) is sunk with at least one sealing ring (132, 138) in between.

30. The piston pump of claim 29, wherein, The at least one sealing ring (132, 138) circumferentially surrounds the guide body (108).

31. The piston pump of claim 29, wherein, The guide body (108) has an outwardly projecting annular protrusion (134) to which a radially inwardly pointing step (136) of the housing recess (46) of the first housing part (14) is assigned, wherein a sealing ring (138) is arranged between the protrusion (134) and the step (136).

Images