PUMP AND METHOD FOR ITS MANUFACTURE

Abstract

A method for manufacturing a pump, in particular for a vehicle brake system, includes forming a blind hole in a pump housing starting from a region in the pump housing in which an eccentric opening is provided to accommodate a drive eccentric. The method further includes inserting a pump cylinder into the blind hole from the region of the eccentric opening and securing the pump cylinder in the blind hole from the region of the eccentric opening. A pump is constructed from the method.

Description

PRIOR ART

The invention relates to a pump, in particular for a vehicle brake system, and to a method for the manufacture of such a pump.

A pump is known from DE 199 28 913 A1, in which an individual pump element or a pump unit is formed in a pump housing by a pump piston, which is mounted displaceably in a pump cylinder. The pump piston sucks a brake fluid into the pump cylinder through an inflow opening and conveys it out from the pump cylinder through an outflow opening.

The object of the present invention is to specify a procedure, by means of which such a pump can be manufactured and assembled in a particularly cost-effective manner.

DISCLOSURE OF THE INVENTION

In accordance with the invention, a pump and a method for the manufacture of a pump, in particular for a vehicle brake system, are created, in which a pump housing is provided, a blind hole is formed in the pump housing starting from a region in the pump housing in which an eccentric opening is provided to receive a drive eccentric, a pump cylinder is inserted into the blind hole from the region of the eccentric opening, and the pump cylinder is fixed in the blind hole from the region of the eccentric opening.

By means of the procedure according to the invention, a pump element or a pump unit of a piston pump which can be driven by means of an eccentric is assembled in a blind hole from the region of the associated eccentric opening. This procedure differs from the previous mode of manufacture, in which the pump element is inserted into a through-hole, which has been formed in the pump housing from the outside, into the eccentric opening. This through-hole then has to be closed from the outside, which is generally achieved by means of caulking. The high-pressure region of the pump element is currently located in the pump housing behind this caulking, and therefore the associated caulking is subjected to correspondingly high pressure. By contrast, with the solution according to the invention, the pump element is to be fixed in the blind hole at the end thereof at which the low-pressure region is located. The pressure load of the fixing device is accordingly also lower at this point.

In accordance with the invention, components of an outlet valve are advantageously inserted into the blind hole before the pump cylinder is inserted into the blind hole.

In this development, components of an outlet valve are first inserted at the base region of the blind hole before the pump element itself is then inserted into the blind hole, together with the pump cylinder thereof and generally also with the pump piston pre-assembled therein. The components of the outlet valve placed inside in such a way are preferably, in particular, a valve spring for resiliently biasing a valve body, as well as a valve body for selectively closing a valve opening. By contrast, the valve opening itself is advantageously formed on the pump cylinder so that the outlet valve is completed by the insertion of the pump cylinder into the blind hole.

The pump cylinder is preferably manufactured by means of deep drawing, that is to say in the form of a deep-drawn part.

Deep drawing is a particularly cost-effective method for the manufacture of the pump cylinder assembled in accordance with the invention. The pump cylinder manufactured in such a way indeed has particularly thin walls and therefore, in principle, is less suitable for exposure to pressure. Nevertheless, the deep-drawn pump cylinder can counteract high radial forces, however, since it is assembled in such a way that its wall rests against or is supported against the surrounding valve housing.

Further, at least one opening is advantageously formed in the pump cylinder, in particular chronologically before the step of deep drawing of the pump cylinder.

The opening formed in such a way is preferably used as an outlet opening or valve opening of the outlet valve. It is particularly advantageously molded onto the base of the cup-shaped pump cylinder. The opening is also preferably used as an inlet opening for the pump cylinder, that is to say as the opening through which the pump piston sucks fluid into the pump cylinder. The inlet region of this type of the pump cylinder is particularly advantageously formed with a multiplicity of individual openings so that a filter screen is formed in the outer surface of the preferably cup-shaped pump cylinder.

The pump cylinder is preferably formed in a cup shape with an annular wall and a base surface.

The pump cylinder, which is cup-shaped in such a way, is advantageously also used as early as the assembly process as a receptacle for the pre-assembly of components of the associated pump cylinder. A pre-assembled module is thus formed, which can then be inserted into the pump cylinder in a processing step.

Alternatively or in addition, the pump cylinder is preferably formed with an annular disc facing the region of the eccentric opening.

The annular disc molded onto the annular wall of the pump cylinder in such a cost-neutral manner is preferably used to support an adjacent ring seal.

The pump cylinder is preferably also formed with an annular step facing the region of the eccentric opening.

The annular step, which likewise can be manufactured in such a way at practically no additional cost, is used in particular to receive a ring seal which seals between the inner face of the pump cylinder and the outer face of the pump piston. In the pump cylinder, the ring seal can then also form a module to be pre-assembled, possibly together with the pump piston. In such a pre-assembled state, the ring seal can be introduced into the blind hole of the pump housing without being damaged. In this installed position, the ring seal is covered radially outwardly by the annular step and is accordingly protected within the annular step.

The pump cylinder is advantageously fixed by means of a guide ring placed in the blind hole, said guide ring being used to axially guide a pump piston displaceable in the pump cylinder.

The effect of the guide ring assembled in such a way is two-fold. Firstly, it acts as a radially supporting guide member for the pump piston during axial displacement within the pump piston. Secondly, the guide ring acts as a retaining ring. It prevents the pump cylinder from being displaced axially in the blind hole.

The pump cylinder is also preferably fixed in the blind hole by of means of caulking, in particular by means of caulking the guide ring.

The processing step of the caulking is a method which is to be implemented reliably, even in the case of large-scale production. The retaining forces necessary over the service life of the pump can be ensured in a cost-effective manner by this method. This is the case in particular, as described above, since the caulking takes place on the low-pressure side of the pump element.

The blind hole is preferably formed by means of a hole which is formed through the eccentric opening, which is already formed at this point.

In this development, the eccentric opening is first drilled and then the blind hole is produced through it. The blind hole can also be formed in a region of the valve housing arranged far inside.

The blind hole is preferably closed at the outer face of the pump housing, in particular by means of pressing in a blind plug.

The valve housing is also sealed at its outer face by the closure of this type and is secured against a possible discharge of brake fluid.

An exemplary embodiment of the solution according to the invention will be explained in greater detail hereinafter on the basis of the accompanying schematic drawings, in which:

FIG. 1 shows a longitudinal section of a pump according to the prior art;

FIG. 2 shows a longitudinal section of an exemplary embodiment of a pump having a pump cylinder according to the invention in the installed state; and

FIG. 3 shows the detail III in FIG. 2.

FIG. 1 shows a pump 10 in the form of a piston pump for a hydraulic vehicle brake system (not illustrated further), said pump being used to generate a fluid pressure of brake fluid inside the vehicle brake system. The pump 10 has a cup-shaped pump cylinder 12, which is manufactured in the form of a rotary part and in which a pump piston 16 is mounted displaceably against a helical spring 14. The pump piston 16 conveys the brake fluid through a circular valve opening 17 of an outlet valve 18 formed in the base region of the pump cylinder 12 and into a subsequent outflow 20. The outlet valve 18 has a closing body 22, which is resiliently biased by a helical spring 21. So as to suck brake fluid into the pump cylinder 12, an annular filter 24 is arranged as a separate component at the periphery of said pump cylinder and is followed in the direction of flow by an inlet valve 26 arranged on the pump piston 16. The pump piston 16 is sealed on its low-pressure side against a pump housing 30 by means of a ring seal 28.

FIGS. 2 and 3 illustrate a pump 10 according to the invention, in which an associated pump cylinder 32 is manufactured by means of deep drawing. The deep-drawing process is carried out starting from a metal sheet as a blank, wherein in particular a cup-shaped basic shape has been formed with an annular wall 34 and a base surface 36. The annular wall 34 is comparatively thin and therefore susceptible to bulging, but is arranged in the pump housing 30 with a large area of its outer face resting thereagainst so that compressive forces are transferred to the pump housing 30.

Before the deep-drawing process, a valve opening 38 for the outlet valve 18 is punched from the thin-walled material of the blank in the region of the base surface 36, and many comparatively small inflow openings 40 are punched from the thin-walled material of the blank in the region of the annular wall 34. A filter screen is then produced by these inflow openings 40 in the then finished, deep-drawn pump cylinder 32 and can filter the incoming brake fluid for the inflow thereof.

An annular step 42 has been formed, during the deep-drawing process, at the end of the annular wall 34, opposite the base surface 36. An annular disc 39 covers the ring seal 28 radially from this annular step 42 and also covers a further annular wall 41 axially. The ring seal 28 is thus protected against external mechanical influences.

The pump 10 according to FIGS. 2 and 3 has been manufactured as follows: the pump housing 30 is provided first, and a blind hole 44 with a base 45, a first shoulder 47, a second shoulder 49, and a third shoulder 51 have been formed therein. The blind hole 44 extends from the surface of the square pump housing 30 into said housing and through a region of an eccentric opening 46, which has been formed selectively in the pump housing 30, either before or after the blind hole 44. The eccentric opening 46 is used during operation of the pump 10 to receive a drive eccentric (not illustrated further) for the pump piston 16.

The deep-drawn pump cylinder 32 has then been inserted into the blind hole 44 with its base surface 36 against the shoulder 47 and with its annular step 42 against the shoulder 49. At its open end, the pump cylinder 32 has been fixed by means of a caulking 48 against the shoulder 51, which is located at the end region of the blind hole 44 open towards the eccentric opening 46. A guide ring 50, which is L-shaped in cross-section, has been retained in the blind hole 44 with caulked material by means of the caulking 48 and was previously slid over the pump piston 16 and applied via an end face against the further annular wall 41 of the deep-drawn pump cylinder 32.

Before the pump cylinder 32 is arranged in place, components of the outlet valve 18, namely the helical spring 21 thereof and the closing body 22 thereof, are also inserted at the bottom of the blind hole 44 between the base 45 and the base surface 36 of the pump cylinder 32.

The blind hole 44 is closed after assembly of the pump cylinder 32, in particular with an associated pump piston 16 pre-assembled therein, by means of a blind plug 52, which is pressed into the blind hole 44 at the outer face of the pump housing 30.

Claims

1. A pump, comprising:

a pump housing forming a blind hole, the blind hole being formed starting from a region in the pump housing in which an eccentric opening is configured to receive a drive eccentric; and

a pump cylinder inserted into the blind hole from the region of the eccentric opening, said pump cylinder being fixed in the blind hole from the region of the eccentric opening.

2. The pump as claimed in claim 1, wherein components of an outlet valve are arranged between a base of the blind hole.

3. The pump as claimed in claim 1, wherein the pump cylinder is a deep-drawn part.

4. The pump as claimed in claim 1, wherein the pump cylinder is formed in a cup shape with an annular wall and a base surface.

5. The pump as claimed in claim 1, wherein the pump cylinder is formed with an annular disc facing the region of the eccentric opening.

6. The pump as claimed in claim 1, wherein the pump cylinder is fixed by a guide ring placed in the blind hole and configured to axially guide a pump piston displaceable in the pump cylinder.

7. A method for manufacturing a pump, comprising:

forming a blind hole in a pump housing, the forming of the blind hole starting from a region in the pump housing in which an eccentric opening is configured to receive a drive eccentric;

inserting a pump cylinder into the blind hole from the region of the eccentric opening; and

fixing the pump cylinder in the blind hole from the region of the eccentric opening.

8. The method as claimed in claim 7, further comprising arranging components of an outlet valve in the blind hole before the pump cylinder is inserted into the blind hole.

9. The method as claimed in claim 7, wherein the pump cylinder is formed by deep drawing.

10. The method as claimed in claim 9, further comprising forming at least one opening in the pump cylinder before the pump cylinder is deep drawn.

11. The method as claimed in claim 7, further comprising forming the blind hole by a hole which is formed through the eccentric opening before the blind hole is formed.

12. The pump as claimed in claim 1, wherein the pump is for a vehicle brake system.

13. The method as claimed in claim 7, wherein the pump is for a vehicle brake system.