WO2008128667A1

WO2008128667A1 - Reciprocating pump for a high-pressure cleaning device

Info

Publication number: WO2008128667A1
Application number: PCT/EP2008/002920
Authority: WO
Inventors: Robert Nathan
Original assignee: Alfred Kärcher Gmbh & Co. Kg
Priority date: 2007-04-20
Filing date: 2008-04-12
Publication date: 2008-10-30
Also published as: EP2140140A1; DE102007020300A1

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 and which is connected via a suction valve to a suction line for drawing in fluid and connected via a pressure valve to a pressure line for discharging pressurized fluid, wherein the at least one piston is displaceably held on a piston guide. In order to refine the reciprocating pump such that the danger of a piston seizure is reduced, it is proposed according to the invention that the reciprocating pump comprise a piston chamber for each piston, a piston guide having two guide surfaces aligned true with one another being provided in the piston chamber, the piston making sliding contact with said surfaces.

Description

Piston pump for a high-pressure cleaner

The invention relates to a piston pump for a high-pressure cleaner with at least one pump chamber into which a reciprocable 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 at least one piston is slidably supported on a piston guide.

Such piston pumps are known from DE 198 01 146 Cl. 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 carries at its free end a dispensing device, in particular a spray lance or spray nozzle.

To guide the piston is usually a piston guide is used, which is designed as a separate component and positioned between the piston pump and a pump drive. The piston pump usually has a plurality of pistons, preferably three pistons, each immersed in a pumping chamber and are held together displaceable on the separate piston guide. The piston guide must be aligned exactly with the pumping chambers to prevent the pistons from tilting. The production of the pump chambers and the piston guide must be carried out with very low manufacturing tolerances and the assembly of the piston guide on the piston pump must be carried out very carefully and by experienced personnel. the. Even with proper installation of the piston guide on the piston pump, there is still the danger that during operation of the piston pump, a piston jammed due to the different thermal expansion of the piston guide and surrounding the respective pumping chamber region of the piston pump.

Object of the present invention is to develop a piston pump of the type mentioned in such a way that the risk of jamming a piston is reduced.

This object is achieved in a piston pump of the generic type according to the invention that the piston pump for each piston has a piston chamber in which a piston guide is arranged with two aligned mutually aligned guide surfaces against which the respective piston slidably.

The piston pump according to the invention has a piston chamber for each piston, in which a piston guide is arranged. Each piston is associated with a separate piston guide, and the respective piston guide is positioned in a piston chamber of the piston pump. A common piston guide for all pistons of the piston pump can thus be omitted. Instead, a separate piston guide is used for each piston, which is integrated into the respective piston chamber. Each piston guide has two guide surfaces, which are aligned with each other and to which the respective piston slidingly abuts. It has been found that thereby the risk of jamming a piston can be significantly reduced. Also the manufacture and assembly of the piston pump including the piston guide designed relatively simple and can be done with larger tolerances within a short time. Due to its positioning within the piston chamber, the piston guide has virtually the same temperature as the area of the piston pump surrounding the respective pump chamber. This has the consequence that even during operation mechanical stresses that could lead to jamming of the piston can be kept very low.

A particularly simple assembly is achieved in an advantageous embodiment, characterized in that the piston guide from the pump chamber facing away from the side - that is from behind - can be inserted into the piston chamber.

It is advantageous if the piston guide comprises two fixed in the piston chamber guide elements, each forming a guide surface for the piston. The two guide elements can be arranged axially spaced from each other. However, it can also be provided that the two guide elements lie directly against one another. This will be explained in more detail below.

It is advantageous if at least one guide element is glued into the piston chamber. Preferably, both guide elements are glued into the piston chamber. This facilitates the assembly of the piston guide. Alternatively it can be provided, for example, that at least one guide element is pressed into the piston chamber.

Preferably, at least one guide element is configured as a guide ring surrounding the piston in the circumferential direction. The guide ring can open simple manner are used in the back of the piston chamber and he defines a piston surrounding the piston in the circumferential direction guide surface on which the piston is slidably applied.

In a preferred embodiment, at least one sealing ring is arranged between the two guide surfaces, which surrounds the piston in the circumferential direction. The sealing ring can be designed in the form of an oil seal. Preferably, the sealing ring comprises at least one sealing lip, which rests sealingly on the outer circumference of the piston. It when the sealing ring comprises two V-shaped mutually aligned sealing lips, which rest in each case sealingly on the outer circumference of the piston is particularly favorable.

In a preferred embodiment, a drainage hole opens into the piston chamber between the two guide surfaces. In the event of a leak, liquid can be led out of the piston chamber via the drainage hole.

Conveniently, at least one guide surface is formed by a guide element of the piston guide, which supports a surrounding the piston in the circumferential direction sealing ring in the axial direction. The guide element thus not only serves to guide the piston, but also forms a support for a sealing ring. The sealing ring may for example be designed in the form of a high-pressure seal, with which the pump chamber is sealed against the piston chamber. It can also be provided that the sealing ring is designed as an oil seal, which prevents the penetration of oil into the piston chamber. Preferably, at least one sealing ring is clamped between a constriction of the piston chamber and a guide element of the piston guide. The constriction may be in the form of a step. It can also be provided that the constriction has a conical or rounded shape. By means of the constriction and the guide element arranged at a distance therefrom, a sealing ring can be fixed axially in the piston chamber in a structurally simple manner.

It can also be provided that a sealing ring is clamped between two guide elements, which each form a guide surface for the piston. Such a configuration has the advantage that a narrowing of the crank chamber for supporting the sealing ring can be omitted.

In a particularly preferred embodiment of the invention, the assembly of the piston guide is simplified in that the piston guide forms an insertable into the piston chamber insert with two mutually spaced guide surfaces on which the piston is slidably applied. The insert can be designed in the manner of a cartridge which can be inserted into the piston chamber. The insert can be glued to the piston chamber. It is advantageous if, in addition to the two guide surfaces, the insert has at least one sealing ring which surrounds the piston in the circumferential direction.

Preferably, the insert comprises a front and a rear insert, each forming a guide element with a guide surface and connected to each other. The inserts can be sleeve-shaped, for example.

Preferably, the two insert parts are connected to one another via a plug connection. It can be provided, for example, that one of the insert parts comprises a collar which can be inserted into the other insert part.

The two insert parts can be locked together in a preferred embodiment.

Between the two insert parts, a sealing ring is arranged in an advantageous embodiment of the invention. The sealing ring may be fixed to a retaining ring, which in turn is fixed to at least one insert part. The retaining ring may for example be made of a metal or of a plastic material, for example of a polyamide material.

It is advantageous if, facing away from the rear insert part, a sealing ring is held on the front insert part. The sealing ring may be formed as a high-pressure seal, which seals the pump chamber relative to the piston chamber. For this purpose, the sealing ring may have at least one sealing lip, which is preferably inclined obliquely to the longitudinal axis of the piston in the direction of the pumping chamber.

The following description of preferred embodiments of the invention is used in conjunction with the drawings for further explanation. Show it: FIG. 1 shows a sectional view of a piston pump according to the invention with a first embodiment of a piston guide inserted in a piston chamber;

Figure 2 is a sectional view of a second embodiment of a piston guide for the piston pump of Figure 1;

Figure 3 is a sectional view of a third embodiment of a piston guide for the piston pump of Figure 1 and

FIG. 4 shows a sectional view of a fourth embodiment of a piston guide for the piston pump from FIG. 1.

FIG. 1 schematically shows a piston pump 10 according to the invention. This can be placed in a conventional manner on a pump drive, not shown in the drawing, known per se, which comprises a swash plate against which the piston explained in more detail below.

The piston pump 10 has a plurality of reciprocally movable pistons 12, each of which pass through a piston chamber 14 and dive into a pump chamber 16. Due to the reciprocating movement of the pistons 12, the volumes of the pumping spaces 16 can be changed periodically. The pump chambers 16 are in each case via a suction valve 18 with a suction line 20 in communication, via which a liquid, preferably water, can be sucked from a supply. In addition, the pump chambers 16 are in each case connected via a pressure valve 22 and a central non-return valve common to all pump chambers 16. valve 24 with a pressure line 26 in fluid communication, which opens into a control chamber 28. Connected to the control chamber 28 in the flow direction of the pressurized liquid is a connecting line 30, which opens into an outlet line 34 formed by a pressure port 32, to which, for example, a high-pressure hose can be connected.

Immediately downstream of the central check valve 24 branches off from the pressure line 26 from a bypass line 36, in which a per se known and therefore only schematically illustrated in the drawing bypass valve 38 is arranged. The bypass line 36 connects the pressure line 26 with the suction line 20th

In the control chamber 28, a control piston 40 is slidably held, which is integrally connected to an injector 42. The injector 42 dips into the connecting line 30 and has in the usual way a cross-sectional constriction, from which a supply line 44 branches off via a transverse bore. About the supply line 44 and an adjoining this connecting piece 46 of the pressurized liquid can be added to a chemical.

The injector 42 is arranged on the end face of the control piston 40 facing away from the pressure line 26. On its side facing the pressure line 26, the control piston 40 carries a parallel to the injector 42 and offset to this arranged shift rod 48, which passes through a through hole 50 with its free end portion. By means of the shift rod 48 may be a known per se and therefore not shown in the drawing switching device tion are actuated by the shift rod 48 is moved. By means of the switching device, the pump drive can be switched on and off. For this purpose, the control piston 40 is frontally acted upon by the pressure prevailing in the supply line 44 and the pressure prevailing at the rear of the injector 42. In normal operation of the piston pump 10, the injector 42 is flowed through by pressurized liquid. Here, the cross-sectional constriction of the injector 42 leads to the generation of a negative pressure in the supply line 44 branched off from the injector. The negative pressure is transmitted to the end face of the control piston 40, which is acted upon at the rear by the pressure prevailing upstream of the injector. The thus acting on the control piston 40 pressure difference has the consequence that this occupies a forward position in which the coupled via the shift rod 48 to the control piston 40 switching device 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 26 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 10 in the pressure line 26, a very high pressure builds On and at the same time a flow through the injector 42 is omitted, so that no dynamic pressure reduction occurs in this area. This results in the same pressure on both sides of the control piston 40. Since the acted upon by the pressure of the supply line 44 end face of the control piston is selected to be greater than the pressure applied upstream of the injector 42 back of the control piston 40, the control piston 40 is pushed at identical pressures so far back that the switching device of the shift rod 48th is pressed. Thus, the drive of the piston pump 10 is turned off and a permanent high pressure load of the piston pump is avoided.

To promote the liquid, the pistons 12 are driven to reciprocate. For the axial guidance of the pistons 12, a piston guide, which is arranged in the respective piston chamber 14, is used in each case.

In FIG. 1, a first embodiment of a piston guide is designated by the reference numeral 52. It comprises a first guide element in the form of a first guide ring 54 and a second guide element in the form of a second guide ring 56. The two guide rings 54, 56 are arranged axially spaced from one another and support on their respective end face, which faces the pump chamber 16, a first Sealing element 58 and a second sealing element 60 from. The first sealing element 58 is designed in the form of a high-pressure seal which seals the pump chamber 16 with respect to the piston chamber 14. The second sealing element 60 is formed in the form of an oil seal, which prevents the penetration of oil into the piston chamber 14. For this purpose, it has two V-shaped mutually projecting sealing lips 61, 62, which bear sealingly on the outer circumference of the piston 12.

The first sealing element 58 bears against a conical constriction 64 of the piston chamber 14, and the second sealing element 60 bears against a stepped constriction 65 of the piston chamber 14. Between the first guide ring 54 and the second guide ring 56, the piston 12 is surrounded within the piston chamber 14 by an annular space 67 into which a drainage hole 68 opens.

The two guide rings 54 and 56 each define a guide surface 70 and 71 for the piston 12, which abuts the guide surfaces 70, 71 slidably. The guide surfaces 70 and 71 are aligned with each other. The guide rings 54 and 56 can be used for mounting the piston pump 10 back into the piston chamber 14. For axial fixing of the guide rings 54 and 56, these can be glued to the piston chamber 14.

2 shows a second embodiment of a piston guide is shown, which is generally designated by the reference numeral 74. The piston guide 74 is configured in the form of a preassembled insert and comprises a front insert part 75 and a rear insert part 76, which can be connected to one another via a plug connection and jointly inserted into the piston chamber 14 at the rear. The front insert member 75 forms at its front end a guide ring 78 with a guide surface 79 and the rear insert member 76 forms at a distance from the front guide ring 78, a rear guide ring 81 with a rear guide surface 82. At the two guide surfaces 79 and 82, the piston 12 sliding abut.

On the front guide ring 78, the rear insert part 76 facing away integrally connects a support ring 84, on which the first sealing element 58 can be supported, wherein this is biased in the direction of the pump chamber 16. The rear insert 76 dives with a collar 86 in the front insert part 75, which has a step 88 at a distance from the collar 86. The step 88 forms a constriction of the front insert part 75. Between the step 88 and the end face of the collar 86, a retaining ring 90 is inserted. clamped, which carries a sealing ring 91 with two V-shaped mutually aligned sealing lips 92 and 93. The retaining ring 90 is made of metal, whereas the sealing ring 91 is made of a plastic material.

The front insert part 75 has on the side facing away from the support ring 84 of the front guide ring 78 has a transverse bore 95, which is aligned after insertion of the piston guide 74 into the piston chamber 14 with the drainage hole 68 of the piston chamber 14.

FIG. 3 shows a third embodiment of a piston guide, designated overall by the reference numeral 98, which, like the piston guide shown in FIG. 4, is designed substantially identically to the piston guide 74 illustrated in FIG. 2. For identical components, therefore, FIGS The same reference numerals are used as in Figure 2. With regard to these components reference is made to the above explanations to avoid repetition.

The piston guide 98 shown in Figure 3 differs from the piston guide 74 in that the two insert parts 75 and 76 abut each other in the piston guide 98 without a plug connection is used. The two insert parts 75, 76 are glued together and take between them a retaining ring 99 on which a sealing ring 100 is held with V-shaped mutually aligned sealing lips 101, 102.

FIG. 4 shows a fourth embodiment of a piston guide, which is designated as a whole by the reference numeral 106 and in which likewise two insert parts 75, 76 connected to one another via a plug connection are used come. In the piston guide 106, the step 88 of the front insert part 75 in combination with the end face of the collar 86 of the rear insert 76 forms a dovetail-shaped receptacle for a retaining ring 107 to which a sealing ring 108 with two V-shaped aligned sealing lips 109 and 110 is fixed ,

The piston guides 52, 74, 98 and 106 make it possible in a structurally simple manner to guide the piston 12 of the piston pump 10 reliably in the axial direction, without the risk that the piston 12 tilt. The assembly of the piston guides 52, 74, 98 and 106 is very simple, by being able to be inserted from behind into the piston chamber 14 of the piston pump 10.

Claims

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 to a suction line for sucking liquid and a pressure valve to a pressure line for discharging pressurized liquid, wherein the at least one piston is displaceably held on a piston guide, characterized in that the piston pump (10) has for each piston (12) a piston chamber (14) in which a piston guide (52; 74; 98; 106) is arranged with two in alignment with each other aligned guide surfaces (70, 71, 79, 82), on which the respective piston (12) slidably.

2. Piston pump according to claim 1, characterized in that the piston guide (52; 74; 98; 106) can be inserted from the side facing away from the pump chamber (16) into the piston chamber (14).

3. Piston pump according to claim 1 or 2, characterized in that the piston guide (52; 74; 98; 106) comprises two guide elements (54, 56; 78, 81) fixed in the piston chamber (14), each having a guide surface (70 , 71, 79, 82) for the piston (12) form.

4. Piston pump according to claim 3, characterized in that at least one guide element (54, 56, 78, 81) is glued into the piston chamber (14).

5. Piston pump according to claim 3 or 4, characterized in that at least one guide element as the piston (12) in the circumferential direction surrounding the guide ring (54, 56, 78, 81) is configured.

6. Piston pump according to one of the preceding claims, characterized in that between the two guide surfaces (70, 71, 79, 82) at least one sealing ring (60; 91; 100; 108) is arranged, which surrounds the piston (12) in the circumferential direction ,

7. Piston pump according to one of the preceding claims, characterized in that between the two guide surfaces (70, 71, 79, 82) a drainage hole (68) opens into the piston chamber (14).

8. Piston pump according to one of the preceding claims, characterized in that at least one guide surface (70, 71, 79, 82) of a guide element (54, 56, 78, 81) of the piston guide (52, 74, 98, 106) is formed wherein the guide element (54, 56, 78, 81) supports a sealing ring (58, 60, 91, 100, 108) surrounding the piston (12) in the circumferential direction in the axial direction.

9. Piston pump according to claim 8, characterized in that at least one sealing ring (58, 60) between a constriction (64, 65) of the piston chamber (14) and a guide element (54, 56) of the piston guide (52) is clamped.

10. Piston pump according to claim 8 or 9, characterized in that a sealing ring (91; 100; 108) between two guide elements (78, 81) is clamped, each forming a guide surface (79, 82) for the piston (12).

11. Piston pump according to one of the preceding claims, characterized in that the piston guide (74; 98; 106) forms an insert which can be inserted into the piston chamber (14) with two guide surfaces (79, 82) arranged at a distance from one another, on which the piston ( 12) slidingly abuts.

12. Piston pump according to claim 11, characterized in that the insert has a front and a rear insert part (75, 76) which each form a guide element (78, 81) with a guide surface (79, 82) and are interconnected.

13. Piston pump according to claim 12, characterized in that the two insert parts (75, 76) are connected to one another via a plug connection.

14. Piston pump according to claim 12 or 13, characterized in that between the two insert parts (75, 76) a sealing ring (91, 100, 108) is arranged.

15. Piston pump according to claim 12, 13 or 14, characterized in that on the front insert part (75) the rear insert part (76) facing away from a sealing ring (58) is held.