WO2008128591A1

WO2008128591A1 - Reciprocating pump for a high-pressure cleaning device

Info

Publication number: WO2008128591A1
Application number: PCT/EP2008/001250
Authority: WO
Inventors: Robert Nathan
Original assignee: Alfred Kärcher Gmbh & Co. Kg
Priority date: 2007-04-20
Filing date: 2008-02-19
Publication date: 2008-10-30
Also published as: EP2137410A1; CN101663487A; DE102007020298A1; CN101663487B

Abstract

The invention relates to a reciprocating pump for a high-pressure cleaning device, comprising at least one pump chamber, into which a reciprocating piston plunges, being connected via a suction valve to a suction line for drawing in fluid and being connected via a pressure valve to a pressure line for discharging pressurized fluid, wherein the reciprocating pump comprises a pump block into which the at least one piston extends, a pump head fitted on the pump block and furthermore the suction line and the pressure line. In order to refine the reciprocating pump such that it has a more simple design, it is proposed according to the invention that the pump head comprise tension rods extending at least partially beyond the pump block in the axial direction and being releaseably connected to the pump drive, wherein the pump block is clamped between the pump head and the pump drive.

Description

Piston pump for a high-pressure cleaner

The invention relates to a piston pump for a high-pressure cleaning device, with at least one pump chamber, in which a reciprocable piston dips and which via a suction valve with a suction line for sucking liquid and a pressure valve with a pressure line for discharging pressurized liquid is connected, wherein the piston pump comprises a pump block, in which projects the at least one piston, and a pump head which is mounted on the pump block and the suction line and the pressure line has.

Such piston pumps are known from DE 195 48 498 C2. With their help, a liquid, preferably water, sucked, placed under pressure and then discharged. An accessory device can be connected to the pressure line, for example a high-pressure hose which leads to a dispensing device.

In DE 195 48 498 C2 it is proposed to clamp the pump head and the pump block by means of a tension element with the pump drive. The tension element can be placed on a discharge nozzle of the pump head and screwed to the pump drive, wherein it acts on the pump head and the pump block with an axial clamping force.

Object of the present invention is to develop a piston pump of the type mentioned in such a way that it has a structurally simpler structure.

This object is achieved according to the invention in a piston pump of the type mentioned in that the pump head comprises tension rods which at least partially overlap the pump block in the axial direction and are releasably connectable to the pump drive, wherein the pump block between the pump head and the pump drive is clamped.

The piston pump according to the invention is characterized by a structurally simple construction. The pump block is clamped between the pump head and the pump drive, separate connection means for fixing the pump block on the pump drive can be omitted. The determination of the pump block on the pump drive is rather via the pump head, which exerts a clamping force on the pump block and is releasably connected by means of its tie rods with the pump drive. The tie rods extend in the axial direction at least over a portion of the pump block, preferably they engage over the pump block completely. Due to their axial alignment, they can control high tensile forces even with relatively little use of material and acting on the pump head bending moments can be kept very low. This makes it possible to provide both the pump block and the pump head with a low material thickness, so that the piston pump according to the invention has a low weight, and yet the liquid to be delivered can be placed under a high pressure, for example a pressure of over 100 bar , The piston pump is thus subject to an occurring in the pump cycle, pulsating pressurization. By the use of the pump block in the axial direction at least partially overlapping tension rods occurring pressure applications can be transformed into a tensile load, which is well manageable even with relatively low material usage. Additional connecting means for the pump block can be completely eliminated, so that the entire piston pump can be fixed solely by means of the tension rods on the pump drive.

Another advantage of the piston pump according to the invention is that the design of the pump block is subject to only limited restrictions. The pump block can therefore be configured in many ways, without the costly precautions must be taken to him reliably set on the pump drive.

It is advantageous if the pump head overhangs the pump block like a hood. It can be provided, for example, that the pump head covers a side facing away from the pump drive end of the pump block, wherein it forms a receptacle for the end face of the pump block and with at least obliquely aligned to the longitudinal axis of the piston pump pull rods the pump block at least partially overlaps.

It is particularly favorable if the pump head is bell-shaped or dome-shaped. It has been found that with such a shaping occurring during operation of the piston pump pulsating pressurization can be safely controlled with low material usage for the pump head and the pump block.

Preferably, the tension rods are screwed to a bearing plate or a housing of the pump drive. By way of example, the pump drive may comprise a gear housing which surrounds a swash plate on which the and her movable piston abut. The tension rods can be screwed to the gearbox housing. However, it can also be provided that the tension rods can be screwed to a piston guide of the pump drive. The piston guide can form a cover of the transmission housing.

A particularly simple assembly of the piston pump according to the invention is achieved in a preferred embodiment in that the contact surfaces of the tie rods define a parting plane on the pump drive. The arrangement of the contact surfaces of the tie rods in a common parting plane makes it easier to connect the tie rods with the pump drive, for example, to screw.

Of particular advantage with regard to the highest possible mechanical stability of the piston pump, it is when the separation surface between the pump head and the pump block is curved or stepped, with a central region of the separation surface axially opposite to an edge region of the separation surface in the direction away from the pump drive protrudes. For example, the pump block may have a central portion projecting axially beyond an edge region of the pump block, and the pump head may form a complementary interface with an axially recessed central portion and an edge region protruding from the central portion. It has been shown that a particularly resilient mechanical connection between the pump block and the pump head can be achieved by a curved or stepped separation surface solely by the fact that the pump head is clamped by means of tie rods with the pump drive. Compressive forces that occur in the central area between the pump head and the pump block can be caused by the curved or curved Stepped design of the interface can be controlled safely without the occurring in the pump cycle pulsating pressurization lead to leakage or damage to the piston pump.

In order to simplify the assembly of the piston pump according to the invention, it is provided in a preferred embodiment that the pump head and the pump block form between them a central valve chamber, in which a central check valve is arranged, via which all pump chambers are connected to the pressure line. The pressure line is formed by the pump head and communicates via the central check valve with the pump chambers provided by the pump chambers. For the design of the central valve chamber, the pump block may have an end-side recess and the pump head has a recess on the back, wherein the two recesses are aligned with each other when placing the pump head on the pump block. Before the pump head is placed on the pump block, the central check valve can be inserted into the frontal depression of the pump block. The assembly of the piston pump is thus quite simple.

The central check valve preferably has a valve housing arranged in the central valve chamber, which forms a valve seat and is sealed by a first sealing ring relative to the pump head and by means of a second sealing ring relative to the pump block, wherein the two sealing rings are arranged concentrically to one another. The concentric arrangement of the two sealing rings facilitates assembly and in addition, by the use of the two sealing rings a reliable seal of Valve housing secured against the pump block and the pump head.

It when the two sealing rings are aligned concentrically to the central axis of the piston pump is particularly advantageous.

To seal the boundary between the pump head and the pump block, a sealing ring can be used, which is clamped in the joint area between the pump head and the pump block. The sealing ring may be formed in the usual way in the form of an O-ring.

It is advantageous if the sealing ring clamped between the pump head and the pump block is arranged concentrically to the center axis of the piston pump.

It is particularly advantageous if the sealing ring is clamped between an axially projecting in the direction of the pump block collar of the pump head and a plunging into the collar contact surface of the pump block. It can be provided that the sealing ring surrounds the pump block in the circumferential direction. This facilitates the assembly of the piston pump.

As already explained, the pump head forms the pressure line of the piston pump. In a preferred embodiment, a connection part can be placed on the end face of the pump head, which forms a pressure connection to which, for example, a high-pressure hose can be connected. The connecting part and the pump head can form between them a control chamber for receiving a control piston, which cooperates with a switching device for switching off the piston pump. The control piston is movably held in the control chamber.

Preferably, the piston pump has an injector which is connected to a supply line for a cleaning chemical which can be admixed with the pressurized liquid. The control piston is frontally acted upon by the pressure prevailing in the supply line and the pressure prevailing at the rear of the injector. It is particularly advantageous if the injector is displaceable together with the control piston as a function of the pressures acting on the control piston. In normal operation of the piston pump, the injector is flowed through by the pressurized liquid. Here, a cross-sectional constriction of the injector leads to the generation of a negative pressure in the supply line branching off from the injector. The negative pressure is transmitted to the end face of the control piston, which is acted upon at the back with the pressure prevailing upstream of the injector. The pressure difference thus acting on the control piston has the consequence that this occupies a defined position in which the switching device coupled to it remains unactuated and thus the drive of the pump is not interrupted. If the delivery of pressurized fluid interrupted, for example by closing a connected to the pressure line via a high-pressure hose dispensing device, in particular a jet pipe or a spray lance, then due to the first still working piston pump in the pressure line, a very high pressure builds up and simultaneously is omitted flow through the injector, so that in this area no dynamic pressure reduction occurs. This results in the same pressure on both sides of the control piston. Since the end face of the control piston acted upon by the pressure of the supply line is greater than the rear side acted upon by the pressure upstream of the injector, the control piston is displaced at identical pressures to the extent that the switching device is actuated. This then switches off the drive of the pump. As a result, a permanent high pressure load of the piston pump is avoided.

The following description of a preferred embodiment of the invention serves in conjunction with the drawings for further explanation. Show it :

Figure 1: a schematic side view of a piston pump according to the invention and

FIG. 2 shows a sectional view of the piston pump from FIG. 1.

In the drawing, a piston pump 10 according to the invention is shown schematically. This can be placed on a pump drive 12 shown only in excerpts in the drawing. The pump drive 12 has for this purpose a bearing plate 14 with laterally outwardly projecting screw receivers 15, each having an internal thread, so that in each case a clamping screw 17 can be screwed into a screw 15 of the bearing plate 14. In addition to the bearing plate 14, the pump drive 12 may comprise in a conventional manner a swash plate which is rotated by an electric motor in rotation. The piston pump 10 has a plurality of pistons 19, each immersed in a pump chamber 21 and the pump drive 12 in the usual manner in the pump chamber 21 back and forth can be moved. As a result, the volume of the pumping spaces 21 can be changed periodically.

The pump chambers 21 are connected via a suction valve 23 with a suction line 24 in connection, via which a cleaning liquid can be sucked from a supply. The pump chambers 21 are also in each case via a pressure valve 26 and a common pump chambers 21 common check valve 27 with a pressure line 29 in flow communication, which opens into a control chamber 31. Connected to the control chamber in the flow direction of the pressurized cleaning liquid is a connection line 33, which opens into an outlet line 35 formed by a pressure connection 34. To the discharge nozzle 34 can be connected in a conventional and therefore not shown in the drawing manner any accessory device, such as a high-pressure hose, which leads to a dispensing device, in particular to a jet pipe or a spray lance.

Immediately downstream of the central check valve 27 branches off from the pressure line 29 from a bypass line 37, in which a known per se and therefore only schematically shown in the drawing bypass valve 38 is arranged. The bypass line 37 connects the pressure line 29 to the suction line 24.

In the control chamber 31, a control piston 40 is slidably held, which is integrally connected to an injector 41. The injector 41 dips into the connecting line 33 and has in the usual way a cross-sectional connec- tion, from which a supply line 43 via a transverse bore. Via the supply line 43 and a connecting piece 44 adjoining it, a cleaning chemical can be added to the pressurized cleaning liquid.

The injector 41 is arranged on the end face of the control piston 40 facing away from the pressure line 29. On its side facing the pressure line 29, the control piston carries a parallel to the injector 41 and offset to this arranged switching rod 46 which is like the injector 41 integrally connected to the control piston 40 and passes through a through hole 47 with its free end. With its over the through hole 47 outwardly projecting end portion of the shift rod 46 is connected to a known per se and therefore not shown in the drawing switching device, which is coupled to the pump drive 12. By shifting the switching rod 46, the switching device for switching on and off of the pump drive 12 can be actuated.

As can be seen in particular from FIG. 1, the piston pump 10 comprises a pump block 50 and a pump head 55 as well as a connection part 58. The pump block 50 is clamped between the pump head 55 and the pump drive 12. For this purpose, the pump head 55 obliquely to the central axis 60 aligned, substantially axially extending tension rods 62 which extend on the outside of the pump block 50 and are screwed by means of the clamping screws 17 in a common parting plane 63 with the bearing plate 14 of the pump drive 12. The pump head 50 extends over the pump block 50 in the manner of a bell-shaped or dome-shaped hood. The connecting part 58 is placed on the pump block 50 facing away from the end face on the pump head 55. It comprises the connecting piece 44 and also the pressure port 34 and the connecting line 33. In addition, the connecting part 58 in combination with the pump head 55 forms the subsequent to the pressure line 29 of the pump head 55 control chamber 31.

The pump head 55 and the pump block 50 form when assembled between a central valve chamber 64, in which the central check valve 27 is arranged. The latter has a valve housing in the form of an insert 66, which forms a sealing seat and surrounds an axially movably held closing body 67. The insert 66 is circumferentially surrounded by two ring seals 68, 69 which seal the insert 66 against the pump block 50 and the pump head 55, respectively. To form the central valve chamber 64, the pump head 55 on the back, d. H. facing the pump block 50, a central rear recess and the pump block 50 has the front side, so the pump head 55 faces, a central end-side recess. The two recesses are arranged in alignment with each other.

The bell-shaped or dome-like pump head 55 forms the pump block 50 facing a collar 72, on which an outer sealing ring 43 is arranged, which surrounds a collar 72 facing contact surface 74 of the pump block 50 in the circumferential direction.

The bell-shaped or dome-like configuration of the pump head 55 has the consequence that the separation surface between the pump head 55 and the pump block 50 is curved. A central area of the interface, namely the rich of the separating surface in the amount of the central valve chamber 64, is offset from an edge region of the separating surface, namely the region of the collar 72 in the axial direction. The curvature of the parting surface is continued by the tension rods 62 on the outside of the pump block 50. As a result, the pulsating pressure forces acting in the axial direction can be reliably absorbed by the pump head 55 during the operation of the piston pump 10, without requiring a massive embodiment of the pump head 55 for this purpose. The wall thickness of the pump head 55 can rather be kept relatively small as well as the wall thickness of the pump block 50. This gives the piston pump 10 a total of a low weight. Like the pump block 50, the pump head 55 can be made of metal, in particular in the form of an aluminum die-cast part. The connection part 58 may also be made of metal, preferably of an aluminum material.

Claims

PATENT APPLICATIONS

A piston pump for a high-pressure cleaner, having at least one pumping space in which a reciprocating piston is immersed and which is connected via a suction valve with a suction line for sucking liquid and a pressure valve with a pressure line for discharging pressurized liquid wherein the piston pump comprises a pump block, in which projects the at least one piston, and a pump head, which is mounted on the pump block and the suction line and the pressure line, characterized in that the pump head (55) tension rods (62), which the pump block (50) in the axial direction at least partially overlap and with the pump drive (12) are releasably connectable, wherein the pump block (50) between the pump head (55) and the pump drive (12) is clamped.

2. Piston pump according to claim 1, characterized in that the pump head (55) overhangs the pump block (50) like a hood.

3. Piston pump according to claim 1 or 2, characterized in that the pump head (55) is configured bell-shaped or dome-shaped.

4. Piston pump according to claim 1, 2 or 3, characterized in that the tie rods (62) with a bearing plate (14) or a housing of the pump drive (12) can be screwed.

5. Piston pump according to one of the preceding claims, characterized in that the contact surfaces of the pump rods (62) on the pump drive (12) define a parting plane.

6. Piston pump according to one of the preceding claims, characterized in that the separation surface between the pump head (55) and the pump block (50) is curved or stepped, wherein a central region of the separating surface with respect to an edge region of the separating surface in which the pump drive (12). axially facing away from the direction.

7. Piston pump according to one of the preceding claims, characterized in that the pump head (55) and the pump block (50) between them form a central valve chamber (64) in which a central check valve (27) is arranged, via which all pump chambers ( 21) are connected to the pressure line (29).

8. Piston pump according to claim 7, characterized in that the central check valve (27) on an axially extending central axis (60) of the piston pump (10) is arranged.

9. Piston pump according to claim 7 or 8, characterized in that the central check valve (27) in the central valve chamber (64) arranged valve housing (66) which forms a valve seat and by means of a first sealing ring (68) relative to the pump head ( 55) and by means of a second sealing ring (69) relative to the pump block (50) is sealed, wherein the two sealing rings (68, 69) are arranged concentrically with each other.

10. Piston pump according to claim 9, characterized in that the two sealing rings (68, 69) are arranged concentrically to the central axis (60) of the piston pump (10).

11. Piston pump according to one of the preceding claims, characterized in that in the joining region between the pump head (55) and the pump block (50) a sealing ring (73) is clamped.

12. Piston pump according to claim 11, characterized in that between the pump head (55) and the pump block (50) clamped sealing ring (73) is arranged concentrically to the central axis (60) of the piston pump (10).

13. Piston pump according to claim 11 or 12, characterized in that the sealing ring (73) between a in the axial direction of the pump block (50) projecting collar (72) of the pump head (55) and in the collar (72) dipping contact surface (74 ) of the pump block (50) is clamped.

14. Piston pump according to one of the preceding claims, characterized in that the front side of the pump head (55), a connecting part (58) can be placed, which has a discharge nozzle (34).

15. Piston pump according to claim 14, characterized in that the

Pump head (55) and the connecting part (58) between them form a control chamber for receiving a control piston (40) which cooperates with a switching device for switching off the pump drive (12).