EP1047878A1

EP1047878A1 - Piston pump for a high-pressure cleaning device

Info

Publication number: EP1047878A1
Application number: EP98966605A
Authority: EP
Inventors: Thomas BÄRLIN; Robert Nathan; Joachim Daiss
Original assignee: Alfred Kaercher SE and Co KG
Current assignee: Alfred Kaercher SE and Co KG
Priority date: 1998-01-14
Filing date: 1998-12-01
Publication date: 2000-11-02
Anticipated expiration: 2018-12-01
Also published as: AU2412899A; ATE216465T1; DE19801146C1; CN1285898A; DE59803886D1; DK1047878T3; US6428291B1; WO1999036700A1; JP2002509225A; EP1047878B1; ES2175856T3; CN1110634C

Abstract

In the case of a reciprocating pump for a high pressure cleaning appliance including a pump housing in which there is disposed at least one pumping chamber having an inlet valve, an outlet valve and a reciprocating piston that projects thereinto in sealed manner, said pump housing comprising a pump block and a pump head which abut closely together at a interface, wherein the pumping chambers and/or the connecting conduits penetrate the interface in sealed manner and, in the region of the interface, accommodate inserts that are insertable into the pumping chambers and/or the connecting conduits from the interface, said inserts being fixed between the pump block and the pump head when in their inserted position, it is proposed that the whole construction be simplified by making the inserts themselves and the region of the pumping chambers and the connecting conduits in which the inserts are accommodated out of a thermally softenable synthetic material, and by connecting the inserts to the wall of the pumping chamber or the connecting conduit in which they are accommodated by means of a welded joint.

Description

Piston pump for a high pressure cleaning device

The invention relates to a piston pump for a high-pressure cleaning device with a pump housing, in which at least one pump chamber with an inlet valve and an outlet valve is arranged, in which a recurrently driven piston plunges in a sealed manner, the pump housing comprising a pump block and a pump head, which lie close to each other on a separating surface, the pumping chambers and / or connecting lines penetrating the separating surface in a sealed manner and in the region of the separating surface receiving insertable inserts into the pumping chambers and / or the connecting lines, which in the inserted position between the pump block and the Pump head are set.

In an effort to make piston pumps for high-pressure cleaning devices increasingly compact and lighter, many have started to also manufacture the pump housing from plastic. Difficulties arise in the construction of high-pressure pumps in that very high forces can occur in the area of the separating surface between the pump block and the pump head. These are caused by inserts that are inserted into the pumping chambers or the connecting lines and that are clamped in the area of the separating surface between the pump head and the pump block. Due to the high pressure of the funded media, these inserts can large forces act in the axial direction, and these forces must be absorbed in conventional pump designs by tensioning the pump head and pump block against each other. Complex safety measures are necessary to prevent the pump housing from "breathing" as a result of the pulsating pressures occurring in the pump cycle, for example the pump heads must be covered with metal caps.

It is an object of the invention to design a generic piston pump in such a way that such forces in the area of the pump head and pump block are avoided.

This object is achieved according to the invention in a piston pump of the type described in the introduction in that the pumping chambers and the connecting lines in the receiving area of the inserts and the inserts consist of a thermally softenable plastic material and that the inserts are connected by welding to the wall of the pumping chamber or connecting line receiving them are.

In contrast to known constructions, the inserts in the pumping chambers and connecting lines are therefore not fixed by being clamped between the pump head and pump block, but rather the inserts are permanently welded to the wall of the pump head or the pump block surrounding them.

Furthermore, it can be provided that the pump block and pump head, at least in the area of the separating surface, consist of a nem softenable plastic material and are connected to each other by a weld at the interface. This eliminates the need for complex screw connections, the welding is sufficient to permanently connect the pump block and pump head to one another, in particular with a view to the fact that the forces in the contact area between the pump head and the pump block are reduced in that the inserts in the connecting lines and / or the Pump chambers are fixed by welding.

In a further preferred embodiment it can be provided that the pump housing has a connection for the suction of a chemical with a valve insert, which is inserted into a receptacle of the pump housing, and that the valve insert and the receptacle, at least in its contact area, consist of a softenable plastic material and in this contact area are connected to each other by a weld. In this embodiment, a valve insert is fixed in a receptacle by welding softenable plastic materials not only in the area of the separating surface, but also with other valve inserts, in this case with a valve insert for a chemical suction.

According to preferred embodiments, the welding can be carried out in various ways, for example the welding can be an ultrasonic welding, a vibration welding, a friction welding or a mirror welding. In the case of ultrasonic welding, the parts to be welded are moved against one another with a small amplitude and high frequency, for example rotated relative to one another about the longitudinal axis of the pumping chamber or the connecting line, and this movement causes such a strong heating in the contact area that the plastic material both the surrounding wall and of use melts. The molten plastic materials mix and form a reliable weld between the insert and the surrounding wall after cooling and the associated solidification. This welded joint not only has the advantage that the inserts are permanently fixed in the inserted position in the pumping chamber or the connecting line, but all axial forces are also absorbed via the welded joint, so that no axial forces are present in the area of the interface between the pump head and the pump block must be transmitted, which could lead to a "breathing" of the pump housing during operation. Finally, there is an optimal seal between the insert and the surrounding wall, so that additional seals can be dispensed with in this area, for example it is no longer necessary to arrange O-ring seals on the outer circumference of the inserts.

In the case of vibration welding, the parts to be welded are moved against one another at a frequency which is substantially lower than that of ultrasonic welding, namely by vibrating one of the two parts to be welded relative to the other. The relative movement that occurs and the friction between the parts to be welded result in heating. tion that softens the material to be welded.

A similar procedure is used for friction welding, in which the parts to be welded are heated and melted by a more or less continuous movement and the resulting frictional heat.

Finally, during mirror welding, thin heating elements are introduced in the area of the contact surface of the two parts to be connected, which are removed after the adjacent material has melted. The melted material can then mix intimately with one another and form the welded joint. In the case of an insert which is inserted into a pumping chamber or bore, the thin heating elements could, for example, be designed in the manner of a sector diaphragm, which are drawn radially inward into the interior of the insert after the material has been heated and then after the weld connection has been formed from the insert can be pulled out.

It is favorable if the insert is a sleeve.

In a preferred embodiment it can be provided that the edge of the sleeve facing away from the separating surface is designed as a sealing seat for a valve body. Such a valve body exerts large forces on its sealing seat in the axial direction; these forces can be introduced by the insert directly into the surrounding wall by means of ultrasonic welding, without this forces are transmitted to the other part of the pump housing.

It is also favorable if the sleeve is designed as a sealing sleeve and protrudes beyond the separating surface. The protruding part can then be immersed in corresponding parts of the pumping chambers or connecting lines in the other part of the pump housing and there effect a seal in the separating surface area.

In a further preferred embodiment it is provided that the insert serves as a support for a spring which pushes a valve body against a sealing seat

A particularly favorable embodiment is one in which it is provided that the insert and the pumping chamber or connecting line receiving it bear ring shoulders which abut against one another when the insert is inserted and, after the material has been thermally softened by the ultrasonic welding, deformed and welded to one another when the insert is further inserted become.

In such an embodiment, the ring shoulders abut each other in the direction of insertion, during ultrasonic welding and the micro-movement of the two parts produced thereby, the ring shoulders are heated in this contact area so that the material melts and mixes in this area. In this way, when the insert is pressed in, an optimal material penetration and thus a reliable sige welded connection, which extends in the axial direction practically over the entire insertion depth of the insert, starting with the first contact of the ring shoulders of the insert or the pumping chambers or connecting line.

It is also possible to incorporate ring grooves into the mutually facing wall parts of the insert or the pumping chambers or connecting lines, these ring grooves serve to hold molten material and additionally lead to a form-fitting and material-fitting connection of the insert to the surrounding wall.

The following description of preferred embodiments of the invention serves in conjunction with the drawing for a more detailed explanation. Show it:

Figure 1: a longitudinal sectional view through a

Piston pump for a high pressure cleaning device;

Figure 2 is an enlarged detail sectional view of the pump block with an attached ultrasonic welding tool before performing the weld and

Figure 3: a view similar to Figure 2 without

Ultrasonic welding tool after performing the ultrasonic welding.

The invention is explained below using the example of a piston pump in which three pistons are parallel to one another. are arranged differently, these pistons are driven via a swash plate, not shown in the drawing. However, it goes without saying that the invention can also be used in piston pumps of a different design, in which the pump housing is divided into two parts which abut one another along a separating surface.

The high-pressure pump 1 shown in the drawing comprises a housing 2 with a pump block 3 and a pump head 4. Pump block 3 and pump head 4 lie flat against one another along a flat separating surface 5 and are clamped against one another by means of clamping means not shown in the drawing, for example by screws.

The pump block 3 accommodates pump chambers 6, into each of which a cylindrical piston 7 is immersed. This piston 7 is sealed off from the pump chamber 6 by suitable seals 8, 9, 10. The piston 7 is oscillatingly inserted into the pumping chamber 6 by a swash plate (not shown in the drawing) and pulled out of it again by a helical spring 11 surrounding it, so that the volume of the pumping chamber 6 changes periodically.

The pump chamber 6 is connected via a connecting line 12 which leads through the separating surface 5 to a suction line 13 which is located in the pump head 4. In the same way, a connecting line 14 leads from the pumping chamber 6 through the separating surface 5 to a pressure line 15 in the pump head 4; a high-pressure line connects to this pressure line 15. device 16 through which conveyed cleaning medium is transported in a manner known per se to a dispensing device, for example a spray lance.

The connecting lines 12 and 14 are sealed against one another in the area of the separating surface 5 by sleeve-shaped inserts 17, 18, which dip into the connecting lines 12 and 14 on both sides of the separating surface 5 and there, in part, via O-ring seals 20 inserted in circumferential grooves 19 for sealing effect surrounding wall.

The insert 17 in the connecting line 12 is essentially a cylindrical sleeve, the edge 21 facing the pump chamber 6 is designed as a sealing seat for a longitudinally displaceable valve body 22 which is pressed against the edge 21 by a compression spring 23. This arrangement forms a suction valve for the pump chamber 6.

The sleeve-shaped insert 17 is provided on its outside with a plurality of steps or ring shoulders 24, which have a very small extension in the radial direction and correspond to the projecting ring shoulders 25 on the inner wall 26 of the connecting line 12.

When the insert 17 is inserted into the connecting line 12, the annular shoulders 24 and 25 strike one another and in this way prevent complete insertion. In this position, an ultrasonic welding tool 27 is placed on the front end of the insert 17 protruding from the pump block 3. set 17 simultaneously presses into the connecting line 12 and the insert 17 moves slightly oscillating with respect to the surrounding inner wall 26. This pressure and the simultaneous periodic movement result in a strong heating of the material in the contact area between the annular shoulders 24 and 25, and this heating leads to the material melting in the contact area. The melted material of the annular shoulders 24 and 25 mixes, and the axial feed exerted by the ultrasonic welding tool 27 allows the insert 17 to be gradually pushed deeper into the connecting line 12, with a mixing of the melted material from the inner wall 26 on the one hand and the insert 17 on the other hand in the contact area results.

In this way, the insert 17 is pushed into the connecting line 12 by a certain feed distance, for example by 1 to 5 mm, and such a insertion height results in a welded connection which, after the material has cooled, not only the insert 17 in the connecting line 12 reliably sets, but also causes an all-round sealing of the insert 17 against the surrounding inner wall 26.

2 shows the state of the insert 17 before the welding process, in FIG. 3 after the welding process has ended. The areas in which the material of the insert on the one hand and the inner wall 26 on the other hand mix to form a welded connection are shown only very schematically in that either the insert or the inner wall is shown. In fact, the materials mix in the contact area and then belong to both the insert and the inner wall.

The high axial forces which are exerted on the insert 17 by the valve body 22 are now introduced exclusively into the inner wall 26 of the pump block 3 by means of this welded connection; the pump head 4 is not acted upon by these axial forces.

In a similar way, the insert 18 is designed as a sleeve-shaped connecting piece, which bridges the connecting line 14 in the region of the separating surface 5 and is sealed off from the inner wall of the connecting line 14 both in the pump block 3 and in the pump head 4 via O-ring seals.

This insert 18 is pressed and welded into the pump block end of the connecting line 14 in a manner similar to the insert 17 by means of ultrasonic welding. It would be entirely possible to omit the O-ring seal on the pump block side of the insert 18, since the welded connection already provides a reliable seal.

In the illustrated embodiment, a compression spring 28 is supported on the end of the sleeve-shaped insert 18 facing the pump chamber 6, which pushes a valve body 29 against a sealing seat 30 on the pump block side. This arrangement forms a pressure valve of the pump chamber 6, and this arrangement also leads to a high axial application of force to the sleeve-shaped insert 18. These axial forces are also completely into the pump block 3 by the welded connection initiated so that no axial forces are transmitted to the pump head 4 in this case either.

Overall, this results in the possibility of connecting the pump head 4 to the pump block 3 without any special axial securing measures; the overall structure is significantly simplified. In particular, this also results in the possibility of connecting pump head 4 and pump block 3 to one another by means of a welded connection, for example pump block 3 and pump head 4 can be made of a softenable plastic material which can be welded in a manner similar to that when the inserts are connected to the Pump block is the case.

In the exemplary embodiment shown and described, the inserts are connected to the pump block by means of ultrasonic welding, but in the case of modified exemplary embodiments this connection can also be carried out by welding of a different type, in particular by vibration welding, friction welding or by mirror welding.

The connection technology described can also be used at other points in the pump housing, for example for fixing a valve insert 31 in a receptacle 32 on the pump head 4; this valve insert is switched into a chemical suction line. This valve insert 31 consists, at least in the area of contact with the receptacle 32, as well as this from a softenable plastic material, so that both parts can be permanently connected to one another by welding.

Claims

P A T E N T A N S P R Ü C H E

Piston pump for a high-pressure cleaning device with a pump housing, in which at least one pump chamber with an inlet valve and an outlet valve is arranged, in which a reciprocatingly driven piston is immersed in a sealed manner, which pump housing comprises a pump block and a pump head, which abut one another on a separating surface, wherein the pumping chambers and / or connecting lines penetrate the separating surface in a sealed manner and in the region of the separating surface receive insertable inserts into the pumping chambers and / or the connecting lines which are fixed in the inserted position between the pump block and the pump head, characterized in that the pumping chambers (6) and the connecting lines (12, 14) in the receiving area of the inserts (17, 18) and the inserts (17, 18) consist of a thermally softenable plastic material and that the inserts (17, 18) are welded to the Wall of them ehmenden pump chamber (6) or connecting line (12, 14) are connected.

2. Piston pump according to claim 1, characterized in that the pump block (3) and pump head (4) at least in the region of the separating surface consist of a softenable plastic material and are connected to one another by a weld at the separating surface.

3. Piston pump according to claim 1 or claim 2, characterized in that the pump housing (2) has a connection for suction of a chemical with a valve insert (31) which is inserted into a receptacle (32) of the pump housing (2), and that the valve insert (31) and the receptacle (32) consist of a softenable plastic material at least in their contact area and are connected to one another by a weld in this contact area.

4. Piston pump according to one of the preceding claims, characterized in that the weld is an ultrasonic weld.

5. Piston pump according to one of claims 1 to 3, characterized in that the weld is a vibration weld.

6. Piston pump according to one of claims 1 to 3, characterized in that the weld is a friction weld.

Piston pump according to one of claims 1 to 3, characterized in that the weld is a mirror weld.

8. Piston pump according to one of the preceding claims, characterized in that the insert (17, 18) is a sleeve.

9. Piston pump according to claim 8, characterized in that the separating surface (5) facing away from the edge (21) of the sleeve is designed as a sealing seat for a valve body (22).

10. Piston pump according to claim 8, characterized in that the sleeve is designed as a sealing sleeve and protrudes over the separating surface (5).

11. Piston pump according to one of the preceding claims, characterized in that the insert (14) serves as a support for a spring (28) which pushes a valve body (29) against a sealing seat (30).

12. Piston pump according to one of the preceding claims, characterized in that the insert (17, 18) and the pump chamber (6) or connecting line (12, 14) carrying the annular shoulders (24 and 25), which when inserting the insert ( 17, 18) lie against each other and after the thermal softening of their material the weld is deformed when the insert (17, 18) is pushed in further and welded to one another.