GB2483331A

GB2483331A - Piston pump with throttle and damping elements

Info

Publication number: GB2483331A
Application number: GB1113462.4A
Authority: GB
Inventors: Oliver Gaertner; Marc Zimmermann; Oliver Hennig
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-09-03
Filing date: 2011-08-03
Publication date: 2012-03-07
Also published as: CN102410171B; DE102010040193A1; DE102010040193B4; KR20120024494A; KR101910917B1; CN102410171A; GB201113462D0

Abstract

In the case of a piston pump 10 for a hydraulic vehicle braking system having an outflow opening 16 for outflowing fluid which is selectively closable by a closing body 26, and having an outflow 18, following in the flow direction, where the closing body 26 has a cap section 32 and a shank section 28 displaceable in a guided manner in a guide bore 24, and the outflow has a damping element 44 for the outflowing fluid. Preferably the outflow is formed with a conduit section 36 parallel to the guide bore forming a flow connection between the cap section and the damping element, bypassing the guide bore. There may be a throttle for the outflowing fluid is arranged at the end of the outflow and another throttle 50 connected in series between the closing body and damping element. A vehicle braking system is also claimed.

Description

I

éscription Title Piston pump having an outflow

Prior art

The invention relates to a piston pump for a hydraulic vehicle braking system having an outflow opening for outilowing fluid, in particular brake fluid, which is selectively closable by a closing body, and having an outflow, following in the flow direction, for the outilowing fluid. The invention further relates to a vehicle braking system having a piston pump of this kind.

A piston pump of this kind is known, for example, from DE 199 28 913 Al. It comprises a pump housing, in which a pump piston is displaceably mounted as the pump element.

The pump piston here conveys a fluid through an outflow opening and a following outf low out of the piston pump. The outflow opening is selectively closable by means of a closing body, whereby the function of an outlet valve is achieved.

As described, for example, in IDE 42 26 646 Al, a piston pump of this kind is customarily followed hydraulically by a damper chamber and a throttle which are both arranged in the pump housing and separately from the piston pump.

It is an object of the present invention to provide a vehicle braking system having a piston pump, the behaviour of which is superior to that of known piston pumps with regard to uniform delivery of fluid in various capacity ranges.

Disclosure of the invention

According to the invention, there is provided a piston pump for a hydraulic vehicle braking system having an outflow opening for outflowing fluid which is selectively closable by a closing body, and having an outflow, following in the flow direction, for the outflowing fluid, in which the closing body is designed with a cap section and a shank section displaceable in a guided manner in a guide bore, and in which the outflow is designed with a damping element for the outflowing fluid.

Furthermore, according to the invention, a vehicle braking system having a piston pump of this kind is provided.

In other words, the essence of the invention lies in the fact that a cap-shaped closing body or a cap of an outlet valve of a piston pump is combined with a damping element.

The damping element is connected to the cap in a flow-conducting manner by means of a connecting conduit. The outlet of the piston pump, i.e. the exit of the outflow, comes after the damping element.

With the configuration according to the invention, there is provided a vehicle braking system whose piston pump delivers a particularly low-vibration and noiseless discharge ofbrakefluid.

According to a first advantageous development of the piston pump according to the invention, the outflow is formed with a conduit section which creates a flow connection between the cap section and the damping element, bypassing the guide bore.

With a development of this kind, the cap and the damping element are directly connected in series, without other possibly flow-disturbing elements lying in between.

By appropriate design of the elements cap and damping element, the flow behaviour of a piston pump of this kind can thereby be comparatively easily and precisely predetermined as desired.

According to a second advantageous development of the piston pump according to the invention, the conduit section is formed substantially parallel to the guide bore.

The parallel arrangement of the conduit section relative to the guide bore can be produced particularly cost-effectively in terms of manufacturing and additionally affords the advantage of a particularly compact construction.

According to a third advantageous development of the piston pump according to the invention, a throttle for the oufflowing fluid is arranged at the end of the outflow.

The outlet of the piston pump according to the invention comes after the damping element. Before the outlet, a throttle is installed according to the last-mentioned development. This throttle, through its damming-up action, improves and assists the functioning of the damping element.

According to a fourth advantageous development of the piston pump according to the invention, a further throttle is connected in series between the closing body and the damping element.

The development of this kind further improves the behaviour of the piston pump with regard to the vibration behaviour of the closing body and the noises arising during opening and closing.

According to a fifth advantageous development of the piston pump according to the invention, the damping element is arranged directly at the outflow conduit of the outf low.

The arrangement of the damping element in this manner directly in the outflow path after the cap-shaped closing body is also referred to as a "series connection" in the present case. For the damping element here in principle acts on the entire outfiowing fluid as the latter passes the damping element on the outflow path.

According to a sixth advantageous development of the piston pump according to the invention, the damping element is arranged at a conduit branching off from the outflow conduit of the outflow.

With this arrangement of a damping element at a branching off from the main flow path of the fluid out of the pump element, a "parallel connection" is created, in which the fluid on the one hand can flow off through the outflow and at the same time is dampened in its fundamentally pulsating flow behaviour by the branching off and the damping element acting there.

According to a seventh advantageous development of the piston pump according to the invention, both the outflow conduit and the branch conduit lead off from the outflow opening.

The outflow opening thus forms a central element, from which the conduit paths extend. This leads to a particularly balanced flow situation at the closing body moving at the outflow opening.

According to an eighth advantageous development of the piston pump according to the invention, the outflow opening is of circular shape and the branch conduit leads off from the outflow opening at the periphery of the outflow opening at an angle of 90° offset with respect to the outflow conduit.

The arrangement of the branch conduit offset in this manner leads to an overall asymmetrical flow situation, whereby in particular the formation of sympathetic vibrations at the closing body can be reduced.

An exemplary embodiment of the solution according to the invention is explained in more detail below with the aid of the appended schematic drawings, in which: Fig. I shows a partial longitudinal section of a first exemplary embodiment of a piston pump according to the invention, Fig. 2 shows a view according to Fig. I where the flow path of outflowing fluid is marked, Fig. 3 shows a connection diagram of the exemplary embodiment according to Figs. I and 2, Fig. 4 shows a connection diagram of second exemplary embodiment of a piston pump according to the invention, Fig. 5 shows a partial longitudinal section of a third exemplary embodiment of a piston pump according to the invention, Fig. 6 shows a connection diagram of the exemplary embodiment according to Fig. 5, and Fig. 7 shows a partially sectioned perspective view of an intermediate body of the exemplary embodiment according to Figs. 5 and 6.

Illustrated in Fig. I is a piston pump 10 for a hydraulic vehicle braking system (not shown in further detail) which serves to generate a fluid pressure of brake fluid within the vehicle braking system. For this purpose, the piston pump 10 has a cup-shaped pump housing 12, in which a pump piston (not shown) is displaceably mounted against a helical spring 14. The pump piston here conveys the brake fluid through a circular outflow opening 16 formed in the bottom region of the pump housing 12 and a following outflow 18 out of the piston pump 10.

The outflow 18 is formed with a cylindrical intermediate insert 20, adjoining the pump housing 12, and a following closing cover 22. A closing body 26 is displaceably mounted in a central guide bore 24 in the intermediate insert 20. The closing body 26 here has a cylindrical shank section 28 which is guided in the guide bore 24 and is urged in the direction of the outflow opening 16 by means of a helical spring 30.

In the switching position shown in Figs. 1 and 2, the closing body 26 bears with a (in the present case) hemispherical cap section 32 against the outflow opening 16. The closing body 26 thus closes the outflow opening 16 in this switching position, but it can also be lifted off the outflow opening 16, counter to the spring force of the helical spring 30, owing to the fluid pressure prevailing in the pump housing 12, whereby an outflow conduit 34 leading through the outflow 18 is opened. Owing to the guidance provided by the shank section 28, the movement of the closing body 26 during this is particularly low in vibration and quiet.

The outflow conduit 34 is formed, in the flow direction directly downstream of the outflow opening 16, with a conduit section 36 which is formed in the intermediate insert eccentrically with respect to the guide bore 24 and so as to bypass the guide bore 24, and substantially parallel to the longitudinal axis thereof. The conduit section 36 leads to a disc-shaped damping space 38 which is formed in the region between the Intermediate insert 20 and the closing cover 22 adjacently to a damper membrane 40.

The damper membrane 40 delimits the damping space 38 from a damper chamber 42 which is formed in the closing cover 22 itself and is filled with gas or another suitable compressible substance. The damper membrane 40 and the damper chamber 42 constitute a damping element 44 for damping pressure surges of the brake fluid flowing out through the outflow 18.

In the flow direction downstream of the damping space 38, a conduit section 46 extending obliquely with respect to the longitudinal axis leads through the intermediate insert 20 to a throttle 48 and finally through the latter out of the intermediate insert 20.

The throttle 48 increases the backpressure within the outflow 18 as the brake fluid flows out and thereby increases the effect of the damping element 44.

The resulting flow path of the brake fluid is illustrated in Fig. 2 by several arrows.

The resulting functional effect of the elements closing body 26, damping element 44 and throttle 48 is shown in the connection diagram according to Fig. 3, which illustrates that these elements act in the form of a series connection (arranged functionally one after the other), since the outflowing brake fluid flows, substantially on its path through the outflow 18, completely through in particular the damping space 38 in front of the damper membrane 40 of the damping element 44 -i.e. the damping element 44 is arranged directly at the outflow conduit of the outflow 18.

Fig. 4 shows, by means of this connection diagram representation of Fig. 3, a further exemplary embodiment of a piston pump 10, in which a further throttle 50 is connected in series between the closing body 26 and the damping element 44. The throttle 50 of this kind would be formed, for example, in the conduit section 36, based on the illustration according to Figs. I and 2.

The arrangement of the damping element in this manner directly in the outflow path after the cap-shaped closing body is also referred to as a "series connection" in the present case. For the damping element here in principle acts on the entire outilowing fluid as the latter passes the damping element on the outflow path.

Figs. 5 and 7 show an exemplary embodiment of a piston pump 101 in which both the outflow conduit 34 and a branch conduit 52 lead off from the outflow opening 16. The branch conduit 52 likewise bypasses (in corresponding fashion to the conduit section 36) the guide bore 24 and leads to a damping space 38 which in this case forms a dead end" in front of a damper membrane 40 of a damping element 44. With the arrangement of a damping element 44 in this manner, the latter is arranged offset from the actual conduit path through the outflow 18 and is thus functionally linked so to speak in the manner of a "parallel connection", which is illustrated in the connection diagram according to Fig. 6.

At the oufflow opening 16 according to Fig. 7, the branch conduit 52 leads off at an angle 54 of 90° offset with respect to the outflow conduit 34. The arrangement offset in this manner result in an asymmetrical flow situation at the cap section 32 of the closing body 26, whereby sympathetic vibrations of the closing body 26 are avoided.

Claims

Claims 1. Piston pump (10) for a hydraulic vehicle braking system having an outflow opening (16) for outfiowing fiuid which is selectively closable by a closing body (26), and having an outflow (18), following in the flow direction, for the outflowing fluid, characterised in that the closing body (26) is designed with a cap section (32) and a shank section (28) displaceable in a guided manner in a guide bore (24), and the outflow (18) is designed with a damping element (44) for the outflowing fluid.
2. Piston pump according to Claim 1, characterised in that the outflow (18) is formed with a conduit section (36) which creates a flow connection between the cap section (32) and the damping element (44), bypassing the guide bore (24).
3. Piston pump according to Claim 2, characterised in that the conduit section (36) is formed substantially parallel to the guide bore (24).
4. Piston pump according to one of Claims I to 3, characterised in that a throttle (48) for the outflowing fluid is arranged at the end of the outflow (18).
5. Piston pump according to Claim 4, characterised in that a further throttle (50) is connected in series between the closing body (26) and the damping element (44).
6. Piston pump according to one of Claims I to 5, characterised in that the damping element (44) is arranged directly at the outflow conduit (34) of the outflow (18).
7. Piston pump according to one of Claims I to 5, characterised in that the damping element (44) is arranged at a conduit (52) branching off from the outflow conduit (34) of the outflow (18).
8. Piston pump according to Claim 7, characterised in that both the outflow conduit (34) and the branch conduit (52) lead off from the outflow opening (16).
9. Piston pump according to Claim 8, characterised in that the outflow opening (16) is of circular shape and the branch conduit (52) leads off from the outflow opening at an angle of 900 offset with respect to the outflow conduit (34).
10. Vehicle braking system having a piston pump (10) according to one of Claims 1 to 9.
11. A piston pump substantially as described herein with reference to the accompanying figures.
12. A piston pump as described herein with reference to Figures 1-3 or Figure 4 or Figures 5-7 of the accompanying figures.
13. A vehicle braking system having a piston pump substantially as described herein with reference to the accompanying figures.