Piston pump for high-pressure cleaning equipment

Abstract

The present invention relates to a piston pump (10) for use in a high-pressure cleaning system, the piston pump having a pump housing (12) including a first housing part (14) and a second housing part (16), each constructed as a metal part. The first housing part (14) defines a suction line (20) and a pressure line (22), and the second housing part (16) defines a plurality of pump chambers (24), each of which receives a reciprocable piston (26, 28). Each of the pump chambers is fluidly connected to the suction line (20) via an inlet channel (32) and to 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 outlet valves 99 each include a stationary outlet valve seat 106 and an outlet closure 114 that is displaceable relative to the outlet valve seat and includes an outlet valve plate 116 that can sealingly abut the outlet valve seat 106. In order to further develop the piston pump 10 in a manner that makes it more cost-effective to manufacture, it is proposed that the second housing part 16 includes a valve receiver 42 through which all outlet channels 34 communicate, and that the piston pump 10 includes an outlet valve assembly 100 that forms all of the outlet valves 99, the outlet valve assembly 100 including an outlet part 102 made of plastic material and inserted into the valve receiver 42 to form all of the outlet valve seats 106.

Description

[Technical Field]

[0001] The present invention relates to a piston pump for a high-pressure cleaning device for conveying a cleaning liquid, the piston pump having a pump housing including a first housing part and a second housing part, each of which is constructed as a metal part, the first housing part forming a suction line and a pressure line, the second housing part forming a plurality of pump chambers, into each of which a reciprocable piston is inserted, each of which is flow-connected with the suction line via an inlet channel and with the pressure line via an outlet channel, each of which is closeable by an inlet valve, each of which is closeable by an outlet valve, and each of which is comprised of an outlet valve seat held stationary and an outlet closure body including an outlet valve plate that is displaceable relative to the outlet valve seat and can sealingly abut against the outlet valve seat. [Background technology]

[0002] Such piston pumps are known from DE 10 2009 049 095 A1. These piston pumps can be used to pressurize a cleaning liquid, such as water, supplied via a suction line and then expel it via a pressure line. For example, a pressure hose can be connected to the pressure line, with a nozzle head at its free end through which pressurized cleaning liquid can be directed toward the object. The piston pump is driven by a drive motor, which is connected to the pistons of the piston pump via, for example, a swash plate transmission, and drives the pistons in a reciprocating stroke motion. The reciprocating movement of each piston into the pump chamber periodically increases and decreases the volume of the pump chamber, and cleaning liquid is sucked into the pump chamber via the inlet channel and expelled under pressure via the outlet channel. The pressure can be, for example, at least 80 bar. To be able to withstand the pressure load, the pump housing includes first and second housing parts, each constructed as a metal part. The first housing part forms a suction line and a pressure line, and the second housing part forms a pump chamber and inlet and outlet channels, the pump chamber being in flow connection with the suction line and the pressure line via the inlet and outlet channels.

[0003] Each inlet channel can be closed by a respective inlet valve, and each outlet channel can be closed by a respective outlet valve. DE 10 2009 049 095 A1 proposes outlet valves each having an outlet part and an outlet closure body that is mutually displaceable with respect to the outlet part. The outlet part forms an outlet valve seat, and the outlet closure body includes an outlet valve plate that can sealingly abut against the outlet valve seat. Each outlet part is held stationary within the outlet channel. Typically, the outlet part is made of stainless steel and is pressed into the outlet channel or is held within the outlet channel by crimping in a rotationally fixed and axially non-displaceable manner.

[0004] WO 2008 / 086950 A1 and EP 2 805 050 B1 disclose piston pumps for high-pressure cleaning systems, in which two housing parts of the pump housing are made of plastic material. This allows the outlet valve seat to be formed directly in the housing part, eliminating the need for an additional outlet part. However, pump housings made of plastic material have lower compressive strength than pump housings made of metal parts. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] DE 10 2009 049 095 A1 [Patent Document 2] WO 2008 / 086950 A1 [Patent Document 3] EP 2 805 050 B1 Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present invention to further develop a piston pump of the type mentioned at the outset in such a way that it can be produced more cost-effectively. [Means for solving the problem]

[0007] This object is achieved according to the invention in that in a piston pump of the general type, the second housing part comprises a valve receiver through which all outlet channels communicate, the piston pump comprises an outlet valve assembly forming all outlet valves, the outlet valve assembly comprising outlet parts made of plastic material and inserted into the valve receiver to form all outlet valve seats.

[0008] The piston pump according to the present invention includes an outlet valve assembly, which forms all of the outlet valves. The outlet valve assembly includes an outlet part, which is inserted into a valve receiver. The valve receiver is formed by the second housing part, which is constructed as a metal part. The outlet part is made of a plastic material and includes all of the outlet valve seats. The outlet valve seats of the piston pump are therefore provided by the outlet part. This eliminates the need to fix individual outlet parts forming the outlet valve seats in the outlet channel for each outlet valve. Complex post-processing of the second housing part, which is constructed as a metal part, can also be omitted. A single outlet part is used, which includes all of the outlet valve seats of the piston pump according to the present invention and is made of a plastic material. This reduces the manufacturing costs of the piston pump and facilitates its assembly.

[0009] The first housing part and / or the second housing part are preferably configured as die-cast or remolded parts.

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

[0011] Preferably, the valve receiver is arranged on the side of the second housing part pointing towards the first housing part.

[0012] The outlet valve assembly is conveniently configured as a pre-assembled unit, which allows the outlet valve assembly to be assembled as a stand-alone unit prior to assembling the complete piston pump, and can be assembled at a first location and then transported to a second location where assembly of the complete piston pump takes place.

[0013] Preferably, the outlet piece includes a plurality of annular outlet valve seat bodies each defining an outlet valve seat.

[0014] Preferably, the outlet valve seat is oriented to align with the outlet channel.

[0015] In a preferred embodiment of the present invention, the second housing part forms a plurality of annular outlet support surfaces in the region of the valve seat, which are oriented perpendicular to the longitudinal axis of the valve seat and adjacent to the outlet channel in the flow direction of the cleaning liquid, and which abut against each of the outlet support surfaces, respectively, via a sealing ring. The perpendicular orientation of the outlet support surfaces allows the sealing rings abutting the outlet support surfaces to be configured as axial seals, so that striations oriented parallel to the longitudinal axis of the valve seat that may occur in the region of the valve seat during manufacturing of the second housing part do not impair the sealing effect of the sealing ring. Such striations may occur, in particular, when the second housing part is configured as a die-cast part that undergoes demolding during its manufacturing. Any striations that occur in the region of the valve seat during demolding extend in the demolding direction, i.e., parallel to the longitudinal axis of the valve seat, and not parallel to the outlet support surfaces. This is because the striations are arranged perpendicular to the longitudinal axis of the valve receiver, so that any striations that occur in the area of ​​the valve receiver during demolding of the second housing part cannot impair the axially acting seal.

[0016] Preferably, each of the outlet support surfaces is adjacent to an outlet channel in the direction of flow of the cleaning liquid.

[0017] As already mentioned, the outlet valve assemblies form all the outlet valves of the piston pump. Advantageously, each of the outlet valves comprises an outlet closure body, which comprises an outlet valve plate mutually displaceable with respect to the outlet part and adapted to sealingly abut an outlet valve seat, and an outlet valve stem adjacent to the outlet valve plate in a direction pointing away from the outlet channel. The outlet valve stem is arranged downstream of the outlet valve seat in the flow direction of the cleaning liquid.

[0018] The outlet valve assembly preferably includes a guide body made of plastic material and including a plurality of guide elements on each of which a respective outlet valve stem is displaceably mounted. In this type of embodiment, all outlet valve stems are guided by the guide body. This further simplifies assembly of the piston pump.

[0019] The guide elements are set to respectively guide the outlet valve stem of the outlet closure.

[0020] In a preferred embodiment of the invention, said guide elements each form a guide receptacle into which an outlet valve stem fits.

[0021] Advantageously, said guide receivers each include at least one internal groove extending in the longitudinal direction of said guide receiver, through which cleaning fluid can escape from each guide receiver.

[0022] Advantageously, an outlet valve spring is respectively clamped between the guide element and the outlet valve plate, by means of which the outlet valve spring can bias the outlet valve plate in a direction towards an associated outlet valve seat.

[0023] In an advantageous embodiment of the invention, the guide body can be releasably and fluid-tightly connected to the outlet part. This makes it particularly simple to configure the outlet valve assembly as a pre-assembled unit. For this purpose, in a first assembly step, the outlet valve shafts can each be inserted into a respective guide holder of the guide body, and in their area protruding from the guide holder, the outlet valve shafts are surrounded by outlet valve springs, one supported on the guide holder and the other supported on the outlet valve plate. The guide body can then be connected to the outlet part in a fluid-tight manner, preferably via an intervening sealing ring. In a subsequent assembly step, the outlet part connected to the guide body can be inserted into the valve holder of the second housing part. The two housing parts of the pump housing can then be joined together.

[0024] Preferably, the guide body is pluggably connectable to the outlet piece with one or more sealing rings interposed therebetween.

[0025] For example, the guide body may be insertable into the outlet piece with at least one sealing ring interposed therebetween.

[0026] It is particularly advantageous if the guide body forms a check valve seat for a central check valve arranged downstream of the outlet valve. In such a configuration, the outlet part forms the valve seat of the outlet valve and the guide body forms the valve seat of the central check valve. This further simplifies assembly of the piston pump. This allows a check valve closing body to be positioned immediately downstream of the check valve seat formed by the guide body and to be biased towards the check valve seat by a check valve spring.

[0027] The central check valve is preferably located in the pressure line.

[0028] The first housing part may include a housing recess on its side pointing toward the second housing part, the housing recess being oriented to align with the valve receptacle of the second housing part, and the guide body may be inserted into the housing recess via at least one sealing ring. In such an embodiment, the outlet valve assembly is positioned between the first housing part and the second housing part, the first housing part including a housing recess on its side pointing toward the second housing part into which the guide body is inserted, and the second housing part including a valve receptacle on its side pointing toward the first housing part, oriented to align with the housing recess, and into which the outlet part is inserted. The guide body is connected to the first housing part in a liquid-tight manner, the outlet part is connected to the second housing part in a liquid-tight manner, and further the guide body and the outlet part are connected to each other in a liquid-tight manner.

[0029] The pressure line is advantageously adjacent to the outlet valve assembly in the direction of flow of the cleaning liquid.

[0030] Advantageously, the at least one sealing ring circumferentially surrounds the guide body, the sealing ring being arranged between the guide body and the housing recess of the first housing part.

[0031] It is particularly advantageous if the guide body includes an outwardly protruding annular protrusion associated with a step of the housing recess directed radially inward relative to the longitudinal axis of the housing recess, with a sealing ring arranged between the annular protrusion and the step. The sealing ring can form an axial seal, and striations do not impair the sealing effect of the sealing ring. Striae may occur in the region of the housing recess during production of the first housing part and are oriented parallel to the longitudinal axis of the housing recess. Such striations may occur, in particular, when the first housing part is constructed as a die-cast part that undergoes demolding during its production. Any striations that occur in the region of the housing recess during demolding extend in the demolding direction, i.e., parallel to the longitudinal axis of the housing recess, and not parallel to the radially inward step. Therefore, any striations that occur in the region of the housing recess during demolding of the first housing part do not impair the axially acting seal.

[0032] In an advantageous embodiment, the inlet valves each have an inlet part inserted into the inlet channel and an inlet closure body mutually displaceable with respect to the inlet part, the inlet part including an inlet valve seat and a guide member arranged offset from the inlet valve seat, the inlet closure body including an inlet valve plate that can sealingly abut against the inlet valve seat and an inlet valve stem adjacent to the inlet valve plate and displaceably mounted on the guide member, the inlet part made of plastic material and including an annular inlet valve seat body that points towards the pump chamber and forms the inlet valve seat, the guide member being arranged upstream of the inlet valve seat in the flow direction of the cleaning liquid, thereby achieving a further reduction in the manufacturing costs of the piston pump according to the invention.

[0033] In this configuration of the piston pump, the second housing parts form inlet channels into which inlet pieces made of plastic material are inserted. The inlet pieces include annular inlet valve seat bodies that point toward the associated pump chamber and form the inlet valve seats. Upstream of the inlet valve seat bodies with respect to the flow direction of the cleaning liquid, i.e., offset from the inlet valve seat body in the direction of the suction line, the inlet pieces form a guide member on which the inlet closure body is displaceably mounted. The inlet pieces being made of plastic allow for cost-effective provision of inlet valve seats without the need for complex post-processing of the second housing parts. Because the inlet pieces are made of plastic, their manufacturing costs are relatively low. The inlet pieces can be inserted into the inlet channels from the side of the inlet channel that points toward the associated pump chamber, so that the guide member formed by the inlet piece is located upstream of the inlet valve seat and therefore outside the pump chamber. This makes it possible to minimize the volume of the pump chamber that cannot be displaced by the piston when moving towards the inlet valve, i.e. the so-called dead space, thereby improving the suction characteristics of the piston pump.

[0034] Advantageously, the inlet valve seat body projects from the inlet channel in the direction of the pumping chamber.

[0035] Advantageously, the second housing part forms an annular inlet support surface adjacent to the inlet channel in the direction of the pump chamber and oriented perpendicular to the longitudinal axis of the inlet channel, against which the inlet valve seat rests with an abutment surface. In such a configuration, the inlet valve seat is supported by the inlet support surface of the second housing part.

[0036] Preferably, the inlet valve seat body includes a sealing ring receptacle adjacent to the abutment surface, in which a sealing ring is arranged for axially sealing the inlet valve seat body against the inlet support surface. The sealing ring, arranged between the inlet valve seat body and the inlet support surface of the second housing part relative to the longitudinal axis of the inlet channel, forms an axially acting seal. This has the advantage that any striations oriented parallel to the longitudinal axis of the inlet channel and occurring during the manufacture of the second housing part, which is constructed as a metal part, do not impair the sealing effect of the sealing ring. Such striations may occur, in particular, when the second housing part is constructed as a die-cast part that is demolded during its manufacture. Any striations occurring during demolding extend in the demolding direction, i.e., parallel to the longitudinal axis of the inlet channel, rather than parallel to the inlet support surface, since the inlet support surface is oriented perpendicular to the longitudinal axis of the inlet channel. Therefore, striations occurring during demolding of the second housing part cannot impair the axially acting seal.

[0037] In an advantageous embodiment of the piston pump according to the invention, the sealing ring holder forms an annular groove circumferentially surrounding the inlet valve seat body, the annular groove comprising a first groove wall adjacent to the abutment surface, on which the outer diameter of the inlet valve seat body continuously decreases with increasing distance from the abutment surface, and a second groove wall adjoins the first groove wall.

[0038] The sealing ring receiver is preferably configured by way of a circumferential groove into which a sealing ring can be inserted, thereby reducing the risk of the sealing ring being unintentionally dislodged from the sealing ring receiver when the inlet piece is inserted into the inlet channel.

[0039] Said first groove wall may for example be configured in a conical manner, the cone angle being preferably between about 10° and 30°, preferably between about 15° and 25°, in particular 20°.

[0040] Advantageously, the outer diameter of the inlet valve seat body increases continuously on the second groove wall with increasing distance from the abutment surface.

[0041] The inlet piece is advantageously held rotationally fixed and axially non-displaceable relative to the inlet channel.

[0042] For example, the inlet part may be hookable to the second housing part.

[0043] In a preferred embodiment of the invention, the inlet part comprises at least one retaining arm, which is adjacent to the inlet valve seat in the direction of the suction line and is held in a rotationally fixed manner relative to the inlet channel. In such an embodiment, the inlet part comprises at least one retaining arm upstream of the inlet valve seat. The retaining arm allows the inlet part to be fixed to the inlet channel in a simple manner, whereby the at least one retaining arm extends into the inlet channel.

[0044] The at least one retaining arm preferably passes through the inlet channel.

[0045] It is particularly advantageous if the at least one retaining arm engages the rear of the inlet channel on the side facing the suction line, which can ensure that the inlet piece can no longer be easily removed from the inlet channel after it has been inserted into the inlet channel from the side pointing towards the associated pump chamber until the at least one retaining arm engages the rear of the inlet channel on the side pointing away from the pump chamber.

[0046] In a preferred embodiment of the invention, the at least one retaining arm is materially bonded to the inlet valve seat body, in such an embodiment the at least one first retaining arm forms together with the inlet valve seat body an integral plastic moulded part.

[0047] Preferably, the inlet part comprises two retaining arms diametrically opposed with respect to the longitudinal axis of the inlet channel, which allow the inlet part to be constructed with mirror symmetry and therefore highly flexible.

[0048] As already mentioned, the inlet closure body comprises an inlet valve stem which is displaceably mounted on a guide member of the inlet part, which guide member is advantageously fixed to the at least one retaining arm.

[0049] Preferably, the guide member is materially bonded to the at least one retaining arm. In such an embodiment, the guide member together with the at least one retaining arm, and preferably together with the inlet valve seat body, form a one-piece plastic moulded part.

[0050] Advantageously, the at least one retaining arm includes an end portion which points away from the inlet valve seat and extends into a recess in the second housing part.

[0051] In particular, the end portion of the at least one retaining arm may form a positive engagement with the recess of the second housing part, which makes it possible in a simple manner to fix the inlet part to the second housing part in a rotationally fixed manner.

[0052] It is particularly advantageous if the end portion of the at least one holding arm is heat-deformable, so that the at least one holding arm can be easily reshaped by applying heat after insertion into the inlet channel from the side of the inlet channel pointing towards the associated pump chamber. For this purpose, the at least one holding arm may consist of a heat-deformable plastic material.

[0053] The at least one retention arm may, for example, have a straight configuration prior to insertion into the inlet channel and may be thermally deformed into a curved or angled shape after insertion into the inlet channel.

[0054] For example, the end portion of the at least one retaining arm pointing away from the inlet valve seat body is thermally deformed radially outward after inserting the retaining arm into the inlet channel, and after thermal deformation, the end portion is oriented outward with respect to the longitudinal axis of the inlet channel, thereby room The side pointing away from the inlet channel may engage the rear of the inlet channel.

[0055] Advantageously, the inlet part as a whole forms a one-piece molded plastic part.

[0056] Preferably, the inlet piece is made of POM material (polyoxymethylene material).

[0057] The inlet closure body includes an inlet valve plate and an inlet valve stem adjacent to the inlet valve plate on a side pointing away from the pump chamber, the inlet valve plate being able to sealingly abut the inlet valve seat of the inlet part, and the inlet valve stem being displaceably mounted on the guide member of the inlet part. Preferably, the inlet valve plate is materially bonded to the inlet valve stem.

[0058] The guide member is preferably of annular configuration.

[0059] Advantageously, the inlet valve stem passes through the guide member and includes a stem portion that projects from the guide member toward the suction line, a spring holder fixed to the stem, and the inlet valve spring is clamped between the spring holder and the guide member. One end of the inlet valve spring is supported on the spring holder, and the other end is supported on the guide member. The inlet valve spring can apply a spring force to the inlet valve stem and, together with the inlet valve stem, to the inlet valve plate, which is pressed against the inlet valve seat under the action of this spring force. When the piston moving into the pump chamber performs a suction movement, the inlet valve plate can rise from the inlet valve seat against the action of the inlet valve spring, thereby allowing cleaning fluid to flow from the suction line through the inlet valve into the pump chamber. When the piston performs a compression movement in the opposite direction, the inlet valve plate is pressed against the inlet valve seat by the inlet valve spring, so that the cleaning liquid cannot flow back into the suction line through the inlet valve.

[0060] In an advantageous embodiment of the invention, the guide member forms a stop that limits the movement of the inlet valve stem toward the pump chamber, and therefore also the movement of the inlet valve plate toward the pump chamber. As the inlet valve stem moves toward the pump chamber, the spring holder fixed to the inlet valve stem gradually approaches the guide member and finally abuts against the stop. Thus, further movement of the inlet valve stem toward the pump chamber, and therefore further lifting of the inlet valve plate from the inlet valve seat, is prevented.

[0061] For further explanation, preferred embodiments of the present invention will now be described in conjunction with the drawings. [Brief explanation of the drawings]

[0062] [Figure 1] FIG. 1 is a cross-sectional view of a piston pump. [Figure 2] FIG. 2 is an enlarged partial view of the piston pump of FIG. 1. [Figure 3] 3 is an enlarged cross-sectional view of detail X in FIG. 2 showing the outlet valve assembly of the piston pump. [Figure 4] FIG. 2 is a perspective view of a second housing part of the piston pump. [Figure 5] 3 is an enlarged cross-sectional view of detail Y in FIG. 2 showing the inlet valve of the piston pump. [Figure 6] 6 is a cross-sectional view of the inlet valve of FIG. 5 taken along line 6-6. [Figure 7] 6 is a perspective view of the inlet components of the inlet valve of FIG. 5 before assembly. [Figure 8] 8 is a cross-sectional view of the inlet part of FIG. 7. [Figure 9] FIG. 10 is a perspective view of the assembled inlet parts of the inlet valve. [Figure 10] FIG. 10 is a cross-sectional view of the inlet piece of FIG. [Figure 11] FIG. 4 is a cross-sectional view of the outlet valve assembly of FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0063] An advantageous embodiment of a piston pump for a high-pressure cleaning device according to the invention is depicted diagrammatically in the drawings and generally designated by the reference numeral 10. The piston pump 10 can convey a cleaning liquid, preferably water. 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 constructed as metal parts. In the illustrated embodiment, the housing parts 14, 16 are each constructed in the form of an aluminum die-cast part.

[0064] The first housing part 14 defines the front side 18 of the piston pump 10 and forms a suction line 20 and a pressure line 22. The second housing part 16 forms three pump chambers into each of which a piston resides. For a better overview, only one pump chamber 24 and two pistons 26, 28 are shown in the drawings. All pistons are pushed into their respective pump chambers 24 by a swash plate (not shown), known per se, and are pushed back from the pump chambers by coil springs 30 surrounding the respective pistons, so that the volume of the pump chambers 24 varies cyclically.

[0065] Each pump chamber 24 is flow connected to the suction line 20 via an inlet channel 32 in the second housing part 16. Each pump chamber 24 is flow connected to the pressure line 22 via an outlet channel 34 in the second housing part 16. The inlet channels 32 are oriented parallel to one another and each have a longitudinal axis 33.

[0066] Two diametrically opposed recesses 36, 38 of the second housing part 16 adjoin the inlet channels 32 on the side pointing towards the suction line 20. This is particularly clear in Figure 4. In the direction of the pump chambers 24, each inlet channel 34 is adjoined by a respective annular support surface 40. The annular support surfaces 40 are formed by the second housing part 16 and face the respective pump chambers 24. This is particularly clear in Figures 2 and 5. The inlet support surfaces are oriented perpendicular to the longitudinal axis 33.

[0067] Pressurized cleaning fluid can be drawn into the respective pump chambers 24 via the inlet channels 32 and pumped out of the pump chambers 24 via the outlet channels 34. The outlet channels 34 lead into a central valve receiver 42 in the second housing part 16, which is circumferentially defined by a cylindrical wall 44. The valve receiver 42 is arranged on the side of the second housing part 16 pointing towards the first housing part 14 and has a longitudinal axis 43 oriented parallel to the longitudinal axis 33 of the inlet channels 32.

[0068] The first housing part 14 includes a housing recess 46 on the side pointing towards the second housing part 16, the housing recess being oriented to align with the valve receptacle 42 of the second housing part 16, and the housing recess being adjacent to the pressure line 22 in the direction of the front side 18 of the first housing part 14.

[0069] A bypass line 48 branches off from the housing recess 46, the bypass line 48 being formed from the first housing part 14 and having a bypass valve 50 arranged in the bypass line 48. Bypass valves are known per se and are therefore only depicted diagrammatically in the drawings. The bypass line 48 establishes a flow connection between the housing recess 46 and the suction line 20 and can be closed by the bypass valve 50.

[0070] The inlet channels 32 can each be closed by a respective inlet valve 52. The inlet valves 52 are identical and each include an inlet piece 54. The inlet piece is made of a plastic material, preferably a POM material, and is inserted into the inlet channel 32. Additionally, the inlet valves 52 each include an inlet closure body 56, which is axially reciprocable relative to the inlet piece 54.

[0071] The inlet piece 54 includes an inlet valve seat body 60 that forms an inlet valve seat 62 for each inlet valve 52. The inlet valve seat body 60 projects into the respective associated pump chamber 24 and is supported, with an abutment surface 64 facing away from the respective pump chamber 24, on the inlet support surface 40 adjacent the respective inlet channel 32 in the direction of the pump chamber 24.

[0072] Adjacent the abutment surface 64 is a sealing ring receptacle 66 in the form of an annular groove 68 that extends circumferentially around the inlet valve seat body 60 and includes a first groove wall 70 immediately adjacent the abutment surface 64 and a second groove wall 72 adjacent the first groove wall 70. The outer diameter of the inlet valve seat body 60 decreases continuously along the first groove wall 70 with increasing distance from the abutment surface 64. The outer diameter of the inlet valve seat body 60 increases continuously along the second groove wall 72 with increasing distance from the abutment surface 64. This is particularly apparent in Figures 7 and 9.

[0073] The sealing ring receiver 66 receives a first sealing ring 74 which axially seals the inlet valve seat body 60 against the inlet support surface 40 .

[0074] The inlet valve seat body 60 of the inlet part 54 is adjacent, in the direction of the suction line 20, to two diametrically opposed retaining arms 76, 78 relative to the longitudinal axis 33 of the inlet channel 32, which retaining arms 76, 78 pass through the inlet channel 34 and each include an end portion 80, 82 pointing away from the inlet valve seat body 60, which protrude from the inlet channel 32 on the side of the inlet channel 32 pointing away from the pump chamber 24 and which, in the assembled state of the inlet valve 52, penetrate into and positively engage with the recesses 36, 38 of the second housing part 16, thereby engaging at the rear of the respective inlet channel 32, as will be described in more detail below.

[0075] The retaining arms 76, 78 receive 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.

[0076] The guide member 84 is materially bonded to the retaining arms 76 , 78 , which are materially bonded to the inlet valve seat body 60 .

[0077] In the illustrated embodiment, the inlet piece 54 forms a one-piece molded plastic part that defines the inlet valve seat body 60 , the retaining arms 76 , 78 and the guide member 84 .

[0078] The inlet closure body 56 includes an inlet valve plate 88 and an inlet valve shaft 90, the inlet valve shaft 90 being integrally adjacent to the inlet valve plate 88 on a side of the inlet valve plate 88 facing 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 shaft 90 extends through the guide member 84 in a direction towards the section conduit 20.

[0079] A spring holder 94 is fixed to a shaft portion 92 of the inlet valve shaft 90 that protrudes from the guide member 84 in the direction of the suction line 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, one end of which is supported on the spring holder 94 and the other end of which is supported on the guide member 84, and which circumferentially surrounds the inlet valve shaft 90 in the region between the guide member 94 and the spring holder 94. The inlet valve plate 88, which is integrally connected to the inlet valve shaft 90, is pressed against the inlet valve seat 62 of the inlet valve seat body 60 under the action of the inlet valve spring 96, and the inlet valve 52 assumes its closed position.

[0080] Thus, movement of the pistons 26, 28 into their respective pumping chambers 24 in a direction pointing away from the inlet channel 32 causes the inlet valve plate 88 to lift off the inlet valve seat 62 against the spring force of the inlet valve spring 96, thereby opening the inlet valve 52 and unblocking the flow connection from the suction line 20 to the pumping chamber 24, allowing cleaning fluid to flow from the suction line 20 through the inlet channel 32 and into the pumping chamber 24. This allows the cleaning fluid to flow externally around the spring holder 94, inlet valve spring 96 and guide member 84, minimizing flow losses.

[0081] The inlet valve plate 88 can rise from the inlet valve seat 62 until the spring holder 94 abuts against a stop 98 on the guide member 84, which stop 98 is configured as a protrusion or sleeve. The stop 98 thus limits the upward movement of the inlet valve plate 96.

[0082] Thus, as the pistons 26 , 28 move toward the inlet channel 32 , the inlet valve plate 88 assumes its position on the inlet valve seat and irrigation fluid is prevented from flowing back into the aspiration line 20 .

[0083] To assemble the inlet valve 52, the first assembly step is as shown in FIG. 7 and Figure 8As depicted in FIG. 1, the inlet piece 54 can be inserted into the inlet channel 32 from the side pointing toward the pump chamber 24, with the retaining arms 76, 78 first linearly aligned, the abutment surfaces 64 abutting the inlet support surfaces 40, and the end portions 80, 82 of the retaining arms 76, 78 protruding from 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 properly reshaped, and the end portions 80, 82 are forced radially outward into the recesses 36, 38, respectively, forming positive engagement with the recesses 36, 38. As a result, the inlet piece 54 is immobilized axially and is held in a rotationally fixed manner on the inlet channel 32. Thereafter, in a further assembly step, the inlet closure 56 can be mounted onto the inlet piece 54 by inserting an inlet valve stem 90 into the inlet piece 54 from the side pointing toward the pump chamber 24. The inlet valve stem 90 passes through the guide member 84. The inlet valve spring 96 can then be placed on the shaft portion 92 that projects from the guide member 84 in a direction pointing away from the pump chamber 24, and the spring holder 94 can then be fixed to the shaft portion 92. Fixing of the spring holder 94 to the shaft portion 92 can be done, for example, by ultrasonic welding.

[0084] The outlet channels 34 leading into the valve receiver can each be closed by a respective outlet valve 99. The outlet valves 99 are identical and are formed by an outlet valve assembly 100. The outlet valve assembly 100 can be pre-assembled and is received by the valve receiver 42 of the second housing part 16 and the housing recess 46 of the first housing part 14.

[0085] 3 and 11 show an enlarged view of the outlet valve assembly 100. The outlet valve assembly 100 includes an outlet part 102 made of a plastic material, such as a POM material. The outlet part 102 is inserted into the valve receiver 52 and includes a plurality of annular outlet valve seat bodies 104, each of which forms an outlet valve seat 106 for an outlet valve 99.

[0086] In addition to the outlet part 102, the outlet valve assembly 100 includes a guide body 108, which is also made of a plastic material, for example a fiber-reinforced plastic material, and which is connectable in a releasable and liquid-tight manner to the outlet part 102. The guide body 108 defines a guide element 110 in the form of a guide receptacle 112, which is oriented so as to be aligned with the outlet valve seat 106.

[0087] The outlet piece 102 and the guide body 108 house therebetween a plurality of outlet closure bodies 114, which are mutually displaceable relative to the outlet piece 54 and the guide body 108, and each include an outlet valve plate 116 and an outlet valve stem 118 of an outlet valve 99 integrally adjacent the outlet valve plate 116. The outlet valve plate 116 can sealingly abut against the outlet valve seat 106, and the outlet valve stem 118, adjacent the outlet valve plate 116 on the side pointing away from the outlet valve seat 106, extends into the guide receiver 112 in which the outlet valve stem 118 is displaceably mounted.

[0088] Between the guide receiver 112 and the outlet valve plate 116, an outlet valve spring 120 of each outlet valve 99 is clamped, one of the outlet valve springs 120 being supported on the guide receiver 112 and the other being supported on the outlet valve plate 116, and surrounding the outlet valve shaft 118 in the circumferential direction in the region between the outlet valve plate 116 and the guide receiver 112. This is particularly true in the region shown in FIG. 11 This is clear in

[0089] An internal groove 122 extending longitudinally of the guide receiver 112 is molded into the guide receiver 112 and allows cleaning fluid to escape from the guide receiver 112 via the internal groove 122 .

[0090] The second housing part 16 forms annular outlet support surfaces 124 in the region of the valve receiver 42, each adjacent to the outlet channel 34 in the direction of the valve receiver 42 and oriented perpendicular to the longitudinal axis 43 of the valve receiver 42. The outlet valve seat bodies 114 are each supported on the outlet support surface 124 by their end faces 126 pointing away from the respective outlet valve seat 106, and arranged between the end faces 126 and the outlet support surface 124 is a respective second sealing ring 128, which axially seals the respective outlet valve seat body 104 against the second housing part 16.

[0091] The guide body 108 is circumferentially surrounded 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 outlet piece 102 and the guide body 108.

[0092] Adjacent to the annular groove 130 is an annular projection 134 which extends on the outer periphery of the guide body 108 in the direction of the housing recess 46. The housing recess 46 forms a radially inwardly directed step 136 at a distance from the annular projection 134. A fourth sealing ring 138 is positioned between the annular projection 134 and the step 136, and the fourth sealing ring 138 axially seals the guide body 108 relative to the first housing part 14.

[0093] In its area extending into the housing recess 46, the guide body 108 forms a check valve seat 140 pointing away from the outlet piece 102, against which a check valve closing body 142 can sealingly abut. The check valve seat 140 combines with the check valve closing body 142 to form a central check valve 144.

[0094] The outlet valve assembly 100 is configured as a pre-assembled unit that can be inserted into the valve receiver 42 and housing recess 46 during assembly of the piston pump 10. This makes assembly of the piston pump 10 easier, as the outlet valve assembly 100 forms all of the outlet valves 99.

[0095] As already mentioned, the two housing parts 14 and 16 are constructed as metal parts. The provision of the inlet valve 52 and the outlet valve 99 here does not require any post-processing of the metal parts, since the inlet part 54 and the outlet part 102 are inserted into the metal parts in the form of plastic elements to provide valve seats. Therefore, the piston pump 10 can be manufactured cost-effectively.

[0096] Furthermore, the volume of the pump chamber 24 that cannot be displaced by the pistons 26, 28 of the piston pump 10 can be kept low, so that the piston pump 10 is characterized by good suction characteristics.

Claims

1. A piston pump for a high-pressure cleaning device for conveying cleaning liquid, The pump housing (12) includes a first housing part (14) and a second housing part (16), each of which is constructed as a metal part; the first housing part (14) defines a suction line (20) and a pressure line (22); the second housing part (16) defines a plurality of pump chambers (24), each of which receives a reciprocable piston (26, 28), and each of which is in flow communication with the suction line (20) via an inlet channel (32) and with the pressure line (22) via an outlet channel (34); each of the inlet channels (34) is closable by an inlet valve (52), and each of the outlet channels (34) is closable by an outlet valve (99); Each of the outlet valves (99) includes an outlet valve seat (106) held stationary and an outlet closure body (114) including an outlet valve plate (116) that is displaceable relative to the outlet valve seat (106) and that can sealingly abut the outlet valve seat (106). In a piston pump, the second housing part (16) includes a valve receptacle (42) through which the outlet channel (34) communicates; and the piston pump (10) includes an outlet valve assembly (100) forming all outlet valves (99), the outlet valve assembly (100) including an outlet part (102) made of plastic material and inserted into the valve receiver (42) to form all outlet valve seats (106); A piston pump characterized by:

2. 2. The piston pump of claim 1, wherein the outlet valve assembly (100) is configured as a pre-assembled unit.

3. 3. The piston pump of claim 1, wherein the outlet piece (102) includes a plurality of annular outlet valve seat bodies (104), each of the plurality of annular outlet valve seat bodies (104) defining an outlet valve seat (106).

4. 4. The piston pump according to claim 3, wherein the second housing part (16) forms a plurality of annular outlet support surfaces (124) in the region of the valve receiver (42), the plurality of annular outlet support surfaces (124) being oriented perpendicular to the longitudinal axis (43) of the valve receiver (42) and each adjacent to an outlet channel (34) in the flow direction of the cleaning liquid, and a respective outlet valve seat body (104) abutting against each of the plurality of annular outlet support surfaces (124) with a sealing ring (128) interposed therebetween.

5. 5. The piston pump according to claim 1, wherein the outlet closure bodies (114) each include an outlet valve stem (118) adjacent the outlet valve plate (116) in a direction pointing away from the outlet channel (34).

6. 6. The piston pump of claim 5, wherein the outlet valve assembly (100) includes a guide body (108) made of a plastic material and including a plurality of guide elements (110) on each of which an outlet valve stem (118) is displaceably mounted.

7. 7. A piston pump according to claim 6, characterized in that the guide elements (110) each form a guide receptacle (112) into which an outlet valve stem (118) fits.

8. 8. The piston pump of claim 7, wherein each of the guide receivers (112) includes at least one internal groove (122) extending in the longitudinal direction of the guide receiver (112).

9. 9. A piston pump according to claim 6, 7 or 8, characterized in that an outlet valve spring (120) is clamped between the guide element (110) and the outlet valve plate (116), respectively.

10. 10. The piston pump according to any one of claims 6 to 9, characterized in that the guide body (108) is connectable to the outlet piece (102) in a releasable and liquid-tight manner.

11. 11. The piston pump according to claim 6, wherein the guide body (108) forms a check valve seat (140) for a central check valve (144) arranged downstream of the outlet valve (99) in relation to the flow direction of the cleaning liquid.

12. 12. The piston pump according to claim 6, wherein the first housing part (14) includes a housing recess (46) oriented to align with the valve receiver (42), and the guide body (108) enters the housing recess (46) with at least one sealing ring (132, 138) interposed therebetween.

13. 13. The piston pump according to claim 12, wherein the at least one sealing ring (132, 138) circumferentially surrounds the guide body (108).

14. 14. The piston pump according to claim 12 or 13, wherein the guide body (108) includes an outwardly protruding annular projection (134) with which a radially inwardly directed step (136) of the housing recess (46) of the first housing part (14) is associated, and a sealing ring (138) is arranged between the projection (134) and the step (136).

15. A piston pump according to any one of claims 1 to 14, Each of the inlet valves (52) includes an inlet part (54) inserted into the inlet channel (32) and an inlet closure (56) mutually displaceable with respect to the inlet part (54); the inlet piece (54) includes an inlet valve seat (62) and a guide member (84) disposed offset relative to the inlet valve seat (62); the inlet closure body (56) includes an inlet valve plate (88) capable of sealingly abutting the inlet valve seat (62), and an inlet valve stem (90) adjacent the inlet valve plate (88) and displaceably mounted on the guide member (84); the inlet piece (54) is made of a plastic material and includes an annular inlet valve seat body (60) facing the pump chamber (24) and forming the inlet valve seat (62); the guide member (84) is arranged upstream of the inlet valve seat (62) in the direction of flow of the cleaning liquid; A piston pump characterized by:

16. 16. The piston pump of claim 15, wherein the inlet valve seat body (60) projects from the inlet channel (32) in the direction of the pump chamber (24).

17. 17. The piston pump according to claim 16, wherein the second housing part (16) forms an annular inlet support surface (40) adjacent to the inlet channel (32) in the direction of the pump chamber (24) and oriented perpendicular to the longitudinal axis (33) of the inlet channel (32), and the inlet valve seat body (60) abuts against the annular inlet support surface (40) with an abutment surface (64).

18. 18. The piston pump of claim 17, wherein the inlet valve seat body (60) includes a sealing ring receptacle (66) adjacent the abutment surface (64), and a sealing ring (74) disposed within the sealing ring receptacle (66) sealing the inlet valve seat body (60) against the annular inlet support surface (40).

19. 19. The piston pump of claim 18, wherein the sealing ring receptacle defines an annular groove circumferentially surrounding the inlet valve seat body, the annular groove having a first groove wall adjacent the abutment surface, on which the outer diameter of the inlet valve seat body continuously decreases with increasing distance from the abutment surface, and a second groove wall adjacent to the first groove wall.

20. 20. The piston pump of claim 19, wherein the outer diameter of the inlet valve seat body (60) increases continuously on the second groove wall (72) as the distance from the abutment surface (72) increases.

21. 21. The piston pump according to claim 15, wherein the inlet part (54) comprises at least one retaining arm (76, 78), which adjoins the inlet valve seat body (60) in the direction of the suction line (20) and is held in a rotationally fixed manner relative to the inlet channel (32).

22. 22. The piston pump according to claim 21, wherein the at least one retaining arm (76, 78) engages the rear of the inlet channel (32) on the side pointing towards the suction line (20).

23. 23. A piston pump according to claim 21 or 22, characterized in that the at least one retaining arm (76, 78) together with the inlet valve seat body (60) form an integral plastic moulded part.

24. 24. A piston pump according to claim 21, 22 or 23, characterized in that the inlet piece (54) comprises two retaining arms (76, 78) diametrically opposed with respect to the longitudinal axis (33) of the inlet channel (32).

25. A piston pump according to any one of claims 21 to 24, characterized in that the guide member (84) is fixed to the at least one retaining arm (76, 78).

26. 26. A piston pump according to any one of claims 21 to 25, characterized in that the guide member (84) together with the at least one retaining arm (76, 78) forms an integral plastic moulded part.

27. 27. The piston pump according to claim 21, wherein the at least one retaining arm (76, 78) includes an end portion (80, 82) that points away from the inlet valve seat body (60) and extends into a recess (36, 38) in the second housing part (16).

28. 28. A piston pump according to claim 27, characterized in that the end portion (80, 82) of the at least one retaining arm (76, 78) engages the recess (36, 38).

29. 29. A piston pump according to claim 27 or 28, characterized in that the end portion (80, 82) of the at least one retaining arm (76, 78) is heat deformable.

30. A piston pump according to any one of claims 15 to 29, characterised in that the inlet part (54) forms a one-piece plastic moulded part.

31. 31. The piston pump according to claim 15, wherein the inlet valve stem (90) passes through the guide member (84) and includes a stem portion (92), the stem portion (92) protruding from the guide member (84) in the direction of the suction line (20), a spring holder (94) fixed to the stem portion (92), and an inlet valve spring (96) is clamped between the spring holder (94) and the guide member (84).

32. 32. The piston pump of claim 31, wherein the guide member (84) forms a stop that limits movement of the inlet valve plate (88) toward the pump chamber (24).

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