US20130243629A1

US20130243629A1 - Pump having a pump cylinder

Info

Publication number: US20130243629A1
Application number: US13/823,016
Authority: US
Inventors: Andreas Schubitschew; Oliver Gaertner
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-09-14
Filing date: 2011-07-18
Publication date: 2013-09-19
Also published as: EP2616680A1; WO2012034737A1; DE102010040701A1

Abstract

A pump, in particular for a vehicle brake system, includes a pump piston which is guided displaceably in a pump cylinder. The pump cylinder is produced by deep drawing.

Description

PRIOR ART

The invention relates to a pump, in particular a piston pump for a vehicle brake system, having a pump piston, which is guided displaceably in a pump cylinder. The invention further relates to a vehicle brake system having a pump of this type and also to a method for producing such a pump.
A pump of this type is known for example from DE 199 28 913 A1. It comprises a pump housing, in which, as an individual pump element or pump unit, a pump piston is mounted displaceably in a pump cylinder. Here, the pump piston draws a brake fluid through an inlet opening into the pump cylinder and conveys it out from the pump cylinder through an outlet opening.
The object of the present invention is to create a pump that can be produced and assembled in a cost-effective manner.

DISCLOSURE OF THE INVENTION

A pump, in particular for a vehicle brake system, which is formed with a pump piston, which is guided displaceably in a pump cylinder, is created in accordance with the invention. Here, the pump cylinder is produced specifically by means of deep drawing.
Deep drawing is a production method that is very cost-effective in principle because a high degree of deformation with simultaneously high dimensional accuracy can be provided with this method by means of an individual deep drawing or pressing process carried out on a workpiece. However, deep drawing generally means that only very thin-walled workpieces can be processed and produced. These workpieces then have comparatively low resistance or rigidity accordingly with respect to compressive load and in particular with respect to buckling, which actually makes them seemingly unsuitable for the use as pump cylinders.
The invention is based on the finding that a deep-drawn pump cylinder can still be used for a pump. The actual problem of low resistance or rigidity can be counterbalanced and completely compensated for, specifically by a further embodiment of the surrounding environment of the pump cylinder deep-drawn in this way.
In order to achieve the necessary rigidity, it is advantageous in particular if the pump cylinder is received in a pump housing in such a way that it is supported in a planar manner against the pump housing via its outer lateral surface. The support is particularly advantageously created by a fit with just a low fitting tolerance between the outer face of the pump cylinder and the inner face of the respective receiving opening in the pump housing. The fitting tolerance should be selected in such a way that the pump cylinder can still be inserted into the pump housing with reasonable pressing force, but in so doing still comes to bear against the pump housing substantially over its entire surface.
The pump cylinder is particularly preferably beaker-shaped with an annular wall and a base area.
Components of the respective pump unit, such as the pump piston with its respective inlet valve, can advantageously be preassembled in the pump cylinder of this type. The preassembly can be carried out cost-effectively in a workpiece support, in which the pump piston is first inserted, followed by the pump piston. Here, the direction of assembly remains the same, which is advantageous for workpiece-support-based assembly.
Furthermore, a valve opening with a valve body closing it selectively is preferably formed on the base area.
The valve opening arranged in this way can be produced particularly favorably in combination with the deep drawing process because the material region of the base area surrounding said valve opening does not have to be deformed during the deep drawing process itself or only has to be slightly deformed. The base area itself is generally only slightly deformed during the deep drawing process, whereas the material of the annular wall experiences a considerable deformation during the deep drawing process. With the only slightly deformed material region, it is ensured that the valve opening retains its dimensions, even throughout the service life of the respective valve.
With a preferred development of the pump according to the invention, at least one inlet opening to the pump piston is also formed on the annular wall.
The inlet opening of this type can be produced in the thin-walled material of the pump piston by a cost-effective punching process.
A multiplicity of inlet openings, by means of which a filter screen is formed, is particularly preferably formed on the annular wall.
A filter screen can be produced very cost-effectively by means of such a formation of many inlet openings on the pump cylinder since the multiplicity of openings can generally be produced by just one punching process.
Furthermore, there is then no longer any need for an additional component for the filter, and therefore the procurement costs and assembly costs can also be further reduced.
As already mentioned, the at least one opening of this type is particularly preferably produced by means of punching, since this manufacturing method can be carried out very cost-effectively. The punching process is carried out in particular before the pump cylinder has been produced by deep drawing. The punching process can then be carried out on the raw material of the pump cylinder, which is provided as a single sheet metal in substantially planar form. Alternatively or additionally, the opening can be produced by means of laser cutting or etching. The multiplicity of inlet openings themselves can thus be formed very cost-effectively and, at the same time, in a dimensionally accurate manner. The deformation, occurring during the deep drawing process, of the material region in which the inlet openings are located can be taken into account beforehand by a corresponding adaptation of the shape and dimensions of the openings to be punched.
An annular disk is preferably also formed at the end of the annular wall arranged opposite the base area.
The annular disk can be produced in a largely cost-neutral manner by means of the deep drawing process itself. It is advantageously used to support a ring seal, which is arranged next to said annular disc and is used to seal the axially moving pump piston with respect to its surrounding environment. The ring seal constitutes a low-pressure seal, which prevents fluid from escaping from the intake region of the pump piston.
Furthermore, an annular step, in which in particular a ring seal sealing between the pump piston and the pump cylinder is arranged, is preferably formed at the end of the annular wall arranged opposite the base area.
The annular step forms an assembly space for a ring seal, which is advantageously mounted at this point at the same time during the assembly steps and is also protected in this position against damage. The ring seal in particular produces a seal between the pump piston and the pump cylinder. With the solution of this type, a further seal between the pump piston and the pump housing surrounding it outside the pump cylinder can also be omitted since the pump cylinder is sealed with respect to the pump housing. This seal can advantageously be created by means of the pressing of the pump cylinder into the pump housing or by means of a caulking of the pump housing at the open end face of the pump cylinder.
The invention further comprises a vehicle brake system having a pump of this type.
Lastly, the invention also comprises a method for producing a pump having the following steps: forming at least one opening in a sheet metal, deep drawing the sheet metal to form a pump cylinder, in such a way that a valve opening and/or an inlet opening and/or an outlet opening of the pump cylinder is/are formed by the opening, and assembling a pump piston in the pump cylinder of this type. As explained above, these manufacturing steps are then preferably followed by the assembly of the pump cylinder in a pump housing.

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 sectional view of a pump according to the prior art,

FIG. 2 shows a longitudinal sectional view of a first exemplary embodiment of a pump with a pump cylinder according to the invention,

FIG. 3 shows a longitudinal view of the pump according to FIG. 2,

FIG. 4 shows a perspective view of the pump cylinder according to FIGS. 2 and 3, and

FIG. 5 shows a longitudinal sectional view of a second exemplary embodiment of a pump with a pump cylinder according to the invention.

In FIG. 1 a pump 10 in the form of a piston pump for a hydraulic vehicle brake system (not illustrated further) is illustrated and is used for generation of a fluid pressure of brake fluid within the vehicle brake system. To this end, the pump 10 has a beaker-shaped pump cylinder 12, which is produced as 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 an annular valve opening 17, formed in the base region of the pump cylinder 12, of an outlet valve 18 into a subsequent outflow 20. The outlet valve 18 has a spring-biased closure member 22. In order to draw brake fluid into the pump cylinder 12, a ring 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 by means of a ring seal 28 with respect to a pump housing 30.
Pumps 10 according to the invention are illustrated in FIGS. 2 to 5, with which a respective pump cylinder 32 is produced specifically by means of deep drawing. The deep drawing process has been carried out starting from a sheet metal as a blank, wherein a beaker-shaped basic form with an annular wall 34 and a base area 36 has been produced in particular. Here, the annular wall is indeed relatively thin and thus susceptible to buckling caused by a high compressive load, but the pump housing 30 surrounding the pump cylinder 32 is formed in such a way that the annular wall 34 can be supported radially outwardly against the pump housing (see FIGS. 2 and 5), such that the pump cylinder 32 can likewise withstand high internal pressures.
A valve opening 38 for the outlet valve 18 and, in the region of the annular wall 34, many relatively small inlet openings 40 have been punched out beforehand from the thin-walled material of the blank in the region of the base area 36.
With the many inlet openings 40 of this type, a filter screen has been produced very cost-effectively at the pump cylinder 32, which is then deep-drawn and finished, and can filter oncoming brake fluid for the inlet thereof.
During the deep drawing process, an annular disk 42 has also been formed at the end of the annular wall 34 arranged opposite the base area 36. The annular disk 42 supports the ring seal 28 arranged next to it in the axial direction.
With the exemplary embodiment according to FIG. 5, an annular step 44 is formed at this end of the annular wall 34, the ring seal 28 also being covered in the radial direction by said annular step and thus protected.

Claims

1. A pump, comprising:

a pump cylinder; and

a pump piston guided displaceably in the pump cylinder,

wherein the pump cylinder is produced by deep drawing.

2. The pump as claimed in claim 1, wherein the pump cylinder is received in a pump housing in such a way that it is supported in a planar manner against the pump housing via its outer lateral surface.

3. The pump as claimed in claim 1, wherein the pump cylinder is beaker-shaped and has an annular wall and a base area.

4. The pump as claimed in claim 3, wherein the base area defines a valve opening configured to be selectively closed by a valve body.

5. The pump as claimed in claim 3, wherein the annular wall defines at least one inlet opening to the pump piston.

6. The pump as claimed in claim 3, wherein the annular wall defines a multiplicity of inlet openings that form a filter screen on the annular wall.

7. The pump as claimed in claim 4, wherein the valve opening is produced by punching.

8. The pump as claimed in claim 3, wherein an annular disk is formed at the end of the annular wall arranged opposite the base area.

9. The pump as claimed in claim 3, wherein an annular step is formed at the end of the annular wall arranged opposite the base area.

10. A vehicle brake system, comprising:

a pump including:

a pump cylinder; and

a pump piston guided displaceably in the pump cylinder,

wherein the pump cylinder is produced by deep drawing.

11. A method for producing a pump, comprising:

forming at least one opening in a sheet metal;

deep drawing the sheet metal to form a pump cylinder, the sheet metal deep drawn in such a way that one or more of a valve opening, an inlet opening, and an outlet opening of the pump cylinder are formed by the opening; and

assembling a pump piston in the pump cylinder.

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

13. The pump as claimed in claim 7, wherein the valve opening is produced by punching before the pump cylinder has been produced by deep drawing.

14. The pump as claimed in claim 5, wherein the at least one inlet opening is produced by punching.

15. The pump as claimed in claim 14, wherein the at least one inlet opening is produced by punching before the pump cylinder has been produced by deep drawing.

16. The pump as claimed in claim 6, wherein the multiplicity of inlet openings are produced by punching.

17. The pump as claimed in claim 16, wherein the multiplicity of inlet openings are produced by punching before the pump cylinder has been produced by deep drawing.

18. The pump as claimed in claim 9, further comprising a ring seal arranged between the pump piston and the annular step of the pump cylinder.