EP2205866A1

EP2205866A1 - Piston pump for delivering a fluid, and associated brake system

Info

Publication number: EP2205866A1
Application number: EP08804391A
Authority: EP
Inventors: Beate Schumann; Horst Beling; Marc Zimmermann
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2007-10-04
Filing date: 2008-09-18
Publication date: 2010-07-14
Also published as: US20100232994A1; WO2009043733A1; DE102007047417A1; CN101815863A; US9360008B2; CN101815863B

Abstract

The invention relates to a piston pump having a piston assembly (22) which has at least one transverse bore (23) and has a longitudinal bore (24) which corresponds to the at least one transverse bore (23), having a cylinder (28) in which the piston assembly (22) is guided in a longitudinally movable manner, and having an inlet valve (25) which comprises a cage element (31), in which an inlet valve spring (25.2) and an inlet valve sealing element (25.3) are arranged, and a corresponding inlet valve seat (25.1) which is arranged on the piston assembly (22.2), wherein the inlet valve sealing element (25.3) can be pressed sealingly into the corresponding inlet valve seat (25.1) by means of a spring force of the inlet valve spring (25.2) in order to close off the longitudinal bore (24), wherein fluid can be sucked in via the at least one transverse bore (23) which is arranged in the piston assembly (22), which fluid can be conducted through the longitudinal bore (24) via the inlet valve (25) into a compression chamber (28.1) in which a restoring spring (30) for the piston assembly (22) is arranged, and to an associated brake system. The restoring spring (30) is designed as a simple cylindrical spiral spring which is supported axially with an upper end winding (30.1) against the cage element (31) and with a lower end winding (30.2) against a cylinder base (28.2), wherein the cage element (31) has an elastic high-pressure sealing element (31.1) which, in the direction of a cylinder wall (28.4), has a radial support region (31.4) for holding and centring the upper end winding (10.1) of the restoring spring (30), and wherein, in order to guide the restoring spring (30), the cylinder (28) has, at the transition between the cylinder wall (28.4) and the cylinder base (28.2), a cylinder base radius (28.4) which is adapted to the lower end winding (30.2).

Description

description

title

Piston pump for conveying a fluid and associated brake system

State of the art

The invention relates to a piston pump for conveying a fluid according to the preamble of independent claim 1, which is used in particular in brake systems of vehicles.

Such piston pumps are preferably used in vehicles with hydraulic or electrohydraulic vehicle brake systems as reclaim pumps to selectively lower or increase a brake pressure in the wheel brake cylinders, whereby the brake pressure in the wheel brake cylinders can be regulated. Such a control can be performed, for example, in an antilock brake system (ABS), in a traction control system (ASR system), in a vehicle dynamics control system, and so on. Figs. 1 to 3 show a conventional piston pump used in a vehicle brake system. As can be seen from FIGS. 1 to 3, a conventional piston pump 1 comprises a piston assembly 2, which has a first piston element 2.1 with a sealing element 13 and a second piston element 2.2, an inlet valve 5, an outlet valve 6 and a cylinder 8. The inlet valve 5 is formed as a check valve and comprises a cage member 11, in which an inlet valve spring 5.2 and an inlet valve sealing element 5.3 is arranged, wherein the inlet sealing element 5.3 is designed for example as a sealing disc, which can sealingly cooperate with a corresponding inlet valve seat 5.1, the second piston element 2.2 is arranged, wherein the second piston element 2.2 is non-positively connected to the cage member 11. The outlet valve 6 is likewise designed as a spring-loaded check valve and arranged in a cover element 12. The outlet valve 6 is opened when a pressure in a compression chamber 8 is greater than a spring force of an outlet valve spring 6.3 acting on an outlet valve sealing element 6.2 of the outlet valve 6, as a result of which Lassventildelement 6.2 is pressed from a arranged on an outlet 8.3 of the cylinder 8 exhaust valve seat 6.1.

During a suction stroke of the piston assembly 2, fluid is sucked in radially via a filter sleeve 9 and arranged in the first piston element 2.1 transverse bores 3 and passed over the corresponding with the transverse bores 3 longitudinal bore 4 in the second piston element 2.2 and the open inlet valve 5 in the compression chamber 8.1, in the cylinder 8 is arranged between the inlet valve 5 and the outlet valve 6. After reaching a top dead center, the direction of movement of the piston group 2 reverses, so that the second piston element 2.2 is pressed sealingly against the inlet valve sealing element 5.3 with the inlet valve seat 5.1 via the first piston element 2.1 driven by an eccentric 14 arranged in an eccentric space 15 and the inlet valve 5 is closed. Now, a pressure build-up takes place in the compression chamber 8.1 until the pressure in the compression chamber 8.1 is greater than the spring force of the outlet valve 6, as a result of which the fluid under pressure via the outlet opening 8.3 and the opened outlet valve 6 from the pressure chamber 8.1 are not shown Outlet line is passed.

After reaching the bottom dead center, the direction of movement of the piston gnαppe 2 reverses again, so that the exhaust valve 6 closes again and the intake stroke begins again, wherein a restoring force F2 arranged in the compression chamber 8.1 and guided by a cylinder wall 8.4 return spring 10, for example is designed as a spiral spring with ground end turns and is supported on a cylinder base 8.2 and on a cage element 11, acts against the cage element 11 of the inlet valve 5 and thus against the second piston element 2.2, around the piston assembly

2 again to move towards top dead center. Therefore act on the second piston element 2.2, which carries the inlet valve seat 5.1, during operation, axial forces Fl and F2, which causes the one eccentric 14 and introduced via the first piston element 2.1, and on the other effected by the return spring 10 and on the Caged element 11 are introduced, and radial forces F3, by the prevailing

System pressure to be generated.

Disclosure of the invention The piston pump according to the invention according to the features of independent claim 1 has the advantage that a return spring is designed as a simple cylindrical coil spring, that is executed without ground end turns. The return spring designed as a spiral spring is supported axially with an upper end winding on a cage element and with a lower end turn on a cylinder bottom, wherein the cage element has an elastic high-pressure sealing element, which towards a cylinder wall a radial bearing area for receiving and centering the upper end turn The return spring has, and wherein the cylinder, in which the return spring is arranged, at a transition between the cylinder wall and the Zylin- derboden for guiding the return spring has an adapted to the under end winding cylinder bottom radius. Due to the design without ground end turns, the return spring designed as a spiral spring can be produced inexpensively. In addition, the notch stress can be reduced by the cylinder bottom radius, as a result of which the cylinder bottom can be made extremely thin so that the component length can be reduced in an advantageous manner. The cylinder bottom radius corresponds for example to a radius of the spring wire of the return spring. The piston pump according to the invention can be used for example as a return pump in a brake system for a vehicle.

The measures and refinements recited in the dependent claims advantageous improvements of the independent claim piston pump are possible.

It is particularly advantageous that the radial contact area for the upper end of the coil designed as a spiral spring return spring is designed as a radial receiving groove, whereby the return spring designed as a spiral spring can be performed centered centered without sanding Win- ends. Furthermore, the radial receiving groove can be formed on the outer edge as a flexible sealing lip, which closes the compression chamber to the cylinder wall pressure-tight, the sealing lip in the load case can seal pressures up to 100 bar. Due to the combination of the radial receiving groove and the sealing lip, the high-pressure sealing element advantageously builds very short. In addition, the elastic high-pressure sealing element is designed to receive radially acting force components and seal the compression chamber at higher pressures, eg up to 500 bar, via a radial sealing surface against the cylinder wall, wherein the radial sealing surface is formed by a pressure-induced expansion of the high-pressure sealing element, and - A -

wherein the sealing function is then ensured by the entire radial outer diameter of the high-pressure sealing element. Furthermore, the high-pressure sealing element seals axially via an axial sealing surface against a piston assembly, which is returned by the return spring via the high-pressure sealing element into an initial position. Here, the high-pressure sealing element is supported at higher pressures by the rigid cylinder wall and the rigid valve seat, both of which are made of a wear-resistant material. As a result, the high-pressure sealing element only needs to absorb small differential pressure forces and thus experiences only a slight elongation.

In an embodiment of the piston pump according to the invention, the piston assembly comprises a first piston element and a second piston element, wherein an inlet valve seat consists of a wear-resistant material and is arranged on the second piston element which receives axially acting force components. In the second piston element, at least one transverse bore corresponding to a longitudinal bore is introduced, wherein the elastic high-pressure sealing element axially seals against the second piston element via the axial sealing surface. Since the high-pressure sealing element absorbs the radially acting force components, the piston assembly coupled to the high-pressure sealing element only has to absorb the acting axial forces and undergoes no further deformation due to additional radial forces. This division of the axial and radial force components on each component advantageously leads to a reduction in the

Component stress in terms of elongation and stress and allows the execution of the components with a lower component strength. By minimizing the voltage, the at least one suction bore designed as a transverse bore and the corresponding longitudinal bore can be introduced into the second piston element, wherein the cage element with the elastic high-pressure sealing element and the second piston element with the inlet valve seat can be embodied as plastic injection-molded parts. The execution as a plastic injection molded parts advantageously allows a simple, cost-effective production of the components, with a complex shape design is possible. Overall, the piston pump according to the invention allows an extreme Kostenreduzie- rank of Kolbenbaudrappe and easy installation. In addition, the piston pump according to the invention provides improved wicking performance, higher resistance to galling and an extremely short inlet area.

In a further embodiment of the piston pump according to the invention, the first piston element is designed, for example, as a cylindrical needle roller and is advantageously disposed of. se as a mass-produced standard part available. Since a transmission of the driving force of an eccentric is effected via a line contact on the first piston part designed as a solid metal needle roller, preferably as a steel needle roller, the wear can be reduced in an advantageous manner.

Advantageous embodiments of the invention described below, as well as those explained above for better understanding thereof, are shown in the drawings. In the drawings, like reference numerals designate components that perform the same or analog functions.

Brief description of the drawings

Fig. 1 shows a schematic perspective view of a conventional piston pump.

Fig. 2 shows a schematic sectional view of a conventional piston pump.

FIG. 3 shows a schematic perspective illustration of the components of an emissive valve for the conventional piston pump according to FIG. 1 or 2.

4 shows a schematic perspective view of the components of an emissive valve for a piston pump according to the invention.

5 shows a schematic sectional representation of a compression region of a piston pump according to the invention.

Embodiments of the invention

A piston pump according to the invention, which can be used as a return pump in a vehicle brake system, essentially comprises the same components as the conventional piston pump 1 described with reference to FIGS. 1 to 3. Therefore, to avoid text repetition, only the essential differences between the piston pump according to the invention and the conventional piston pump 1 according to FIGS. 1 to 3 described in detail. Unlike the conventional Chen piston pump 1 shown in FIG. 1 to 3, the piston pump according to the invention comprises an improved return spring in combination with a high pressure sealing element.

As can be seen from FIG. 4, the inlet valve 25 of the piston pump according to the invention comprises, analogously to the conventional piston pump 1, a cage element 31, in which a

Inlet valve spring 25.2 and an inlet valve sealing element 25.3, which is designed for example as a sealing ball, and a corresponding inlet valve seat 25.1, which is arranged on a second piston element 22.2 of a piston assembly 22, wherein the inlet valve sealing element 25.3 by a spring force of the inlet valve spring 25.2 sealingly into the corresponding inlet valve seat 25.1 can be pressed.

The piston assembly 22 comprises a first piston element 22.1, which is embodied here by way of example as a cylindrical needle roller, and the second piston element 22.2, wherein the inlet valve seat 25.1 consists of a wear-resistant or of a hard material. In contrast to the conventional piston pump 1, the cage element 31 of the piston pump according to the invention has an elastic high-pressure sealing element 31.1 designed to accommodate radially acting force components F3 and at pressures up to 100 bar via a radial sealing lip 31.2 and at higher pressures via an additional radial Seal sealing surface 31.3 against a cylinder wall 28.4 shown in FIG. 5 and axially sealed against the piston assembly 22 via an axial sealing surface 31.5, ie against the second piston element 22.2, which rests against the axial sealing surface 31.5.

In contrast to the conventional piston pump 1, the second piston element 22.2 receives only the axially acting force components F1 and F2, so that a longitudinal bore 24 and transverse bores 23 corresponding to the longitudinal bore 24 can be introduced in the second piston element 22.2. In the illustrated embodiment, the cage member 31 are executed with the elastic high-pressure sealing element 31.1 and the second piston member 22.2 with the inlet valve seat 25.1 as plastic injection molded parts, which advantageously allows a simple, inexpensive production of the components, with a complex shape design is possible. In addition, the first piston element 22.1 in the illustrated embodiment, fixed to the second

Piston element 22.2 coupled. In one embodiment, not shown, the first piston element 22.1 can be loosely coupled to the second piston element 22.2. Overall, the inventive design of the inlet valve 25 in combination with the piston assembly 22 allows an extreme cost reduction of the piston pump and a simple assembly. In addition, the piston pump according to the invention provides a Improved suction, a higher pressure resistance and an extremely short Emiassbereich available.

As can be seen in FIG. 5, the piston assembly 22 is longitudinally movably guided with the inlet valve 25 in a cylinder 28 of a compression section 40, wherein fluid is drawn radially through the transverse bores 23 in the second piston element 22.2 during a suction stroke of the piston assembly 22 and radially through the transverse bores 23 corresponding longitudinal bore 24 is guided through the open inlet valve 25 in a compression space 28.1. After reaching a top dead center, the direction of movement of the piston group 22 reverses, so that the second piston element 22.2 with the inlet valve seat 25.1 is pressed sealingly against the inlet valve sealing element 25.3 via the first piston element 22.1 driven by an eccentric, not shown, and the inlet valve 25 is closed. Now, a pressure build-up takes place in the compression space 28.1 until the pressure in the compression space 28.1 is greater than the spring force of an exhaust valve, not shown, whereby the pressurized fluid via an outlet 28.3 and the open outlet valve from the pressure chamber 28.1 in a non-illustrated Outlet line is passed.

After reaching the bottom dead center, the direction of movement of the piston group 22 reverses again, so that the exhaust valve closes again and the intake stroke starts again, wherein a restoring force F2 of a arranged in the compression space 28.1 return spring 30, which is designed as a simple coil spring without ground loop ends , presses against a radial bearing area 31.4, which is arranged on the high-pressure sealing element 31.1. The restoring force F2 is axially via the high-pressure sealing element 31.1 and the axial sealing surface 31.5 on the second piston element 22.2, whereby the piston assembly 22 is moved again in the direction of top dead center. The radial receiving area 31.4 is designed for receiving and centering an upper end turn 30.1 of the restoring spring, for example, as a radial Aufhahmeut in which runs as a spiral spring return spring 30 is supported with the upper end turn 30.1. The combination of the radial Aufhahmenut 31.4 and the sealing lip 31.2 builds the

High pressure sealing element 31.1 advantageously very short. Via a lower end turn 30.2, the return spring 30 is supported on a cylinder bottom 28.2. Here, the cylinder 28 at the transition between the cylinder wall 28.4 and the cylinder bottom 28.2 for guiding the return spring 30 has a cylinder bottom radius 28.4 adapted to the end winding 30.2. The cylinder bottom radius 28.4 corresponds to preferred As a result of the embodiment without ground end turns, the return spring 30 designed as a spiral spring can be produced cost-effectively. In addition, the notch stress can be reduced by the cylinder bottom radius 28.5, whereby the cylinder bottom 28.2 is made extremely thin and the component length can be advantageously reduced.

As can be seen further from FIG. 5, the radial annular groove 31.4 is formed on the outer edge as a flexible sealing lip 31.2, which closes off the compression space 28.1 in a pressure-tight manner against the cylinder wall 28.4. Since the elastic high-pressure sealing element 31.1 between the metallic return spring 30 and that of a wear-resistant and therefore harder

Material is arranged second piston element 22.2 is arranged, the radial sealing surface 31.3 expanded due to pressure, so that the high pressure sealing element 31.1 sealingly abuts with its full radial outer diameter of the cylinder wall 28.4. During the compression of the fluid sucked into the compression space 28.1, the high-pressure sealing element 31.1 seals radially against the cylinder wall 28.4 via the radial sealing surface 31.3 and against the second piston element 22.2 through the axial sealing surface 31.5. In addition, the inlet valve sealing element 25.3 seals axially against the inlet valve seat 25.1 in the first piston element 22.2.

In the piston pump according to the invention, the component sizes of the high-pressure sealing element and the cylinder are advantageously reduced. Due to the design without ground end turns, the return spring designed as a spiral spring can be produced inexpensively. Overall, the invention allows a cost-effective and space-optimized piston pump with easy-to-manufacture components, which are designed as plastic injection molded parts, the high-pressure sealing element with support by surrounding components up to 500 bar high pressure, the sealing function in the low pressure range below 100 bar through the sealing lip on the high pressure seal is performed.

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Claims

claims

A piston pump having a piston assembly (22) having at least one transverse bore (23) and a longitudinal bore (24) corresponding to the at least one transverse bore (23), a cylinder (28) in which the piston assembly (22) is longitudinally movably guided and an inlet valve (25) comprising a cage member (31) in which an emirate valve spring (25.2) and an inlet valve sealing element (25.3) is disposed and a corresponding inlet valve seat (25.1) disposed on the piston assembly (22.2), wherein the inlet valve sealing element (25.3) can be pressed sealingly into the corresponding inlet valve seat (25.1) by a spring force of the inlet valve spring (25.2) in order to close the longitudinal bore (24), whereby at least one transverse bore (22) is arranged in the piston assembly (22). 23) fluid can be sucked, which can be conducted through the longitudinal bore (24) via the inlet valve (25) into a compression space (28.1), in which a return spring (30) for the piston assembly (22) is arranged, characterized in that the return spring (30) is designed as a simple cylindrical coil spring which is axially with an upper end turn (30.1) on the cage member (31) and with a lower end turn (30.2) on a Cylinder base (28.2) is supported, wherein the cage member (31) has a resilient high-pressure sealing element (31.1) to a cylinder wall (28.4) towards a radial bearing area (31.4) for receiving and centering the upper end turn (10.1) of the return spring (30) , and where the cylinder

(28) at the transition between the cylinder wall (28.4) and the cylinder bottom (28.2) for guiding the return spring (30) to the under end winding (30.2) adapted Zylindi- derbodenradius (28.4).

2. Piston pump according to claim 1, characterized in that the cylinder bottom radius

(28.4) corresponds to a radius of the spring wire of the return spring (30).

3. Piston pump according to claim 1 or 2, characterized in that the radial bearing area (31.4) is designed as a radial Aufhahmenut (31.4).

4. Piston pump according to claim 3, characterized in that the radial Aufhahmenut (31.4) at the outer edge as a flexible sealing lip (31.2) is formed, which closes the compression space (28.1) to the cylinder wall (28.4) pressure-tight.

5. Piston pump according to one of claims 1 to 4, characterized in that the elastic high-pressure sealing element (31.1) is designed to receive radially acting force components and to seal the compression space (28.1) via a radial sealing surface (31.3) against the cylinder wall (28.4), wherein the radial sealing surface (31.3) can be formed by a pressure-induced widening of the high-pressure sealing element (31.1).

6. Piston pump according to one of claims 1 to 5, characterized in that the high-pressure sealing element (31.1) via an axial sealing surface (31.5) against the piston assembly (22) seals axially.

7. Piston pump according to one of claims 1 to 6, characterized in that the piston assembly (22) comprises a first piston element (22.1) and a second piston element (22.2), wherein the inlet valve seat (25.1) consists of a wear-resistant material and the second piston element (22.1) is arranged, the axially acting Kraftkomponen- accommodates, wherein in the second piston member (22.1) with the longitudinal bore (24) corresponding at least one transverse bore (23) is introduced, and wherein the elastic high-pressure sealing element (31.1) on the axial sealing surface (31.5) axially seals against the second piston element (22.1).

8. Piston pump according to one of claims 1 to 7, characterized in that the cage element (31) with the elastic high-pressure sealing element (31.1) and the second piston element (22.2) are designed as plastic injection molded parts.

9. Piston pump according to claim 7 or 8, characterized in that the first piston element (22.1) is designed as a cylindrical needle roller.

10. Brake system for a vehicle, characterized by a return pump, which is designed as a piston pump (1) according to one of claims 1 to 9.

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