GB2569324A

GB2569324A - Valve cartridge

Info

Publication number: GB2569324A
Application number: GB1720757.2A
Authority: GB
Inventors: Barsan Vlad; Briesewitz Rüdiger; Dolmaya Joseph
Original assignee: Continental Automotive Systems SRL
Current assignee: Continental Automotive Systems SRL
Priority date: 2017-12-13
Filing date: 2017-12-13
Publication date: 2019-06-19
Anticipated expiration: 2037-12-13
Also published as: GB201720757D0; GB2569324B

Abstract

A valve within a valve block for an ABS brake system, comprising an elongated valve seat 201 with first and second inlets 206, 209 and an outlet 211, a pressure regulation spring 202, a piston 203 with radial channels 210, a ball 204 placed against a cone 224, and a suction spring 205 supported by a spring pot 206, wherein the piston is limited by a retaining ring 207 on one side, and by chamfers s on the other, and the radial channels are capable of fully aligning with the second inlet. When pressure increases at the second inlet, the piston rises and reduces the volume of fluid transferred from the second inlet to the outlet. The retaining ring may be placed on a groove g on the inner side of the valve seat. Preferably, the radial channels are connected to additional hydraulic lines to ensure a failsafe mechanism.

Description

Valve Cartridge

The invention refers to a valve cartridge, designed to be used in anti-lock hydraulic brake systems, or any other hydraulic or pneumatic system which requires the delivery of fluid from two inputs to an output.

Hydraulic brake systems for automotive applications typically include a driver-actuated brake pressure generator, such as a booster-aided tandem master cylinder, used to reduce the amount of pedal pressure needed for braking. The tandem master cylinder connects to a reservoir and supplies pressurized brake fluid to a pair of brake circuits. Hydraulically and electronically operated valves control the flow of the brake fluid. Such an electronically controlled hydraulic brake system is described by WO2012161835A1, published on 29 November 2012, belonging to Continental Automotive Systems, Inc.

According to the cited prior art, the hydraulic brake system eguipped for anti-slip control and for active brake interventions has a self-priming pump, at least one electronic shuttle valve, a pressure retention valve and a suction valve with various designs, arranged such as to prevent the brake system's low-pressure accumulator and the wheel brakes from being evacuated below atmospheric pressure during a sensitive braking operation.

Anyway, in that configuration, the main difficulty is raised by fitting separate subassemblies such as the pressure retention valve and the suction valve, both comprised in a block-shaped housing, namely the valve block. They are positioned in the valve block depending on the possibility of making the hydraulic circuit (drilling connecting bores and mounting the separate subassemblies) . Thus, the pressure retention valve is placed close to the low pressure accumulator, while the suction valve is placed on the suction side of the pump. Also, one of the main focuses is to keep the system in a box-volume as low as possible.

The disadvantages of the above-mentioned configuration are mainly the following: almost no space is available for adding additional elements which may be required either to perform new functions or to do the same ones, but with an improved outcome. Introducing a new element would require two separated interfaces to be machined in the valve block, for inserting the pressure retention valve and the new element, respectively, meaning double manufacturing operations and costs; plus, mounting of separate subassemblies in these conditions is difficult and might also increase box-volume . Since the available space is rather limited, there is a constant need for compacting the overall volume occupied by the valve block.

The present invention addresses at least one above-mentioned disadvantage .

Therefore, the technical problem to be solved is to integrate a component with an improved function without affecting the box-volume between the low pressure accumulator, the pump and the electronic shuttle valve.

The object of the invention is to provide a valve cartridge which involves low efforts and costs in manufacturing and mounting into the valve block.

According to the invention, this obj ect is achieved by the subj ect matters of the independent claims, namely a valve cartridge, as well as a valve block equipped with such a valve cartridge.

Further advantageous embodiments are the subject matter of the dependent claims.

According to a first aspect, the invention provides a valve cartridge comprising an elongated valve seat provided with a first inlet at a first pressure, a second inlet at a second pressure, and an outlet at a third pressure, a pressure regulation spring, a piston provided with radial channels, a ball placed against a cone, and a suction spring supported by a spring pot. The stroke of the piston is limited by a retaining ring on one side and on the other by chamfers, the position of the retaining ring on the valve seat corresponds to a full alignment of the piston's radial channels with the second inlet port, in such a manner that it opens a fluid path from the second inlet to the outlet. Pressure rising in the second inlet will cause the piston to rise and decrease the volume of fluid transferred between the second inlet and the radial channels of the piston, gradually balancing the fluid pressures.

By using the valve cartridge according to the invention, the advantages are that, by regulating the pressure from the second inlet to the outlet, the lifetime of the pump increases without impacting the box-volume. This design extends the function of an existing pressure retention valve to regulate the pressure in the circuit after it, while it is mounted in the same spot with minimum impact on other components or from manufacturing side. The overall design is compact and robust and there is no impact on mounting.

The object is also achieved by a preferred embodiment of the invention, wherein the radial channels can be connected to additional hydraulic lines. The specific advantage of the preferred embodiment is that of introducing a failsafe mechanism by not fully closing the second hydraulic circuit.

According to a second aspect, the invention provides a valve block provided with a corresponding profiled bore as to be able to accommodate the mentioned valve cartridge.

By this specific arrangement, the advantage is that only one working interface has to be machined, meaning reduced manufacturing operations and costs.

For a better understanding of the invention and the advantages thereof, exemplary embodiments of the invention are given, with reference to the attached figures, in which similar reference numbers designate similar parts. The figures represent:

Fig. 1 - a schematic view of a prior art electronically controlled brake system, partially shown;

Fig. 2 - a longitudinal section through a valve cartridge according to the invention;

Fig. 3 - a bottom view of the valve cartridge from Fig. 2.

Fig. 1 shows a prior art electronically operated hydraulic brake system, and serves to understand the context of the invention. Such a known hydraulic brake system comprises a reservoir 10, attached to a tandem master cylinder 11 operated by a pedal 12. A brake line 13 conveys brake fluid from the tandem master cylinder 11 and includes a separating valve 14 and an inlet valve 15, both of them electronically operated, and ensures the connection to four wheel brakes 16 (of which only one is shown) . A supply line 17 conveys brake fluid from the tandem master cylinder 11 via an electronic shuttle valve 18. Another electronically operated outlet valve 19 receives pressurized fluid from each wheel brakes 16 via a pressure relief line 21 which connects to a low-pressure accumulator 20. The brake fluid is drawn by a pump 22, being prevented to be drawn from the wheel brakes 16 by a pressure retention valve 23 opening in the direction from low-pressure accumulator 20 to the suction side of the pump 22. Further on, also a suction valve 24 is placed at the suction side of the pump 22, and a pressure valve 25 is placed at the discharge side of the pump 22, in order to prevent a flow of brake fluid from the brake line 13 to the suction side of the pump 22. Optionally, a damping chamber 26 and a throttling orifice 27 soften pressure pulses stemming from the pump 22. The entire assembly of valves 14, 15, 18, 19, 23, 24 and 25 is accommodated by a valve block (not shown), for which the need of a compact, robust design is acute.

Usually, the pressure retention valve used in the prior art is a spring-loaded check valve exerting a bias force that requires a pressure difference of approximately 1 bar to transfer fluid from the low pressure accumulator to the suction valve of the pump .

According to the invention, in order to obtain a compact, robust design, a two-position valve cartridge 200 is arranged between the low-pressure accumulator 20, the suction valve 24 and the electronic shuttle valve 18.

Fig. 2 illustrates the details of a longitudinal section through the valve cartridge 200 in normal position. A valve seat 201 includes a pressure regulating spring 202 which hydraulically engages a piston 203 with an abutment ridge 222 to support the spring 202 . Piston 203 is provided with an internal axial channel, so profiled as to ensure a cone 224 for a ball 204 and support for a spring pot 206. Ball 204 is held against afferent cone 224 by a suction spring 205. The aforementioned elements 203, 204, 205 and 206 replace the pressure retention valve from prior art.

The internal channel of piston 203 widens, the wider section being provided with radial channels 210. In fact, the internal axial channel extends from a first inlet port 208 (the narrower section from top) to an outlet port 211 (the wider section from bottom) . Piston has a stroke h limited at one side by a retaining ring 207 placed onto a groove g of valve seat 201, and at the other side by chamfers s provided on the piston 203 and on valve seat 201, respectively.

Fig. 3 provides a bottom view of a preferred embodiment of the valve cartridge, according to the invention. A particularity of it is that the retaining ring is not fully enclosing the wider section of the valve seat 201, being provided with extended ears 217 at both ends, as to ensure a solid base for piston 203.

The described arrangement controls the hydraulic connection between the first inlet port 208, i.e. at low-pressure accumulator 20 where a first pressure is noted pl, a second inlet (radial) port 209, i.e. at electronic shuttle valve 18 where a second pressure is noted p2, and the outlet port 211, i.e. at suction valve 24 where a third pressure is noted p3.

In the shown embodiment, the radial channel 210 is aligned with the second inlet port 209, which is the normal state of the regulatory valve 200. Increasing the pressure, p2, from the tandem master cylinder 11 via the supply line 17 and the electronic shuttle valve 18, causes the piston 203 to rise, decreasing the transfer area between second inlet port 209 and outlet 211. At the suction side of pump 22, the value of third pressure p3 is different than the value of the first pressure pl. While there is pressure in the second inlet 209 and the outlet 211, the ball 204 is pressed against cone 224 and does not allow any transfer between first inlet 208 and any of the other ports, 209 or 211.

By this arrangement of the valve cartridge, the two pressures, _P2 and p3, are balanced as follows: the second inlet port 209 is opened and the brake fluid goes directly to pump 22 . When pressure p2 increases, it moves piston 203 upwards, which makes second inlet 209 and radial channels 210 to misalign, thus reducing the pressure spikes at outlet 211. Chamfers s on the valve seat 201 and on piston 203 limit the rising of the piston 203, as to ensure that the connection between second inlet 209 and radial channels 210 is always opened. The main benefit of this design is that such a smooth operation also softens the pulses of pressure at the pump's suction side.

Also by this arrangement, the fluid accumulated in the low pressure accumulator 20 is transferred to the suction side of pump 22 via the integrated pressure retention valve comprised of 203, 204, 205, 206 in this manner: when there is sufficient pressure in low pressure accumulator 20 (around 1 bar), the force of suction spring 205 impinges ball 204 down, thus opening the area between ball 204 and cone 224. The fluid thus travels to outlet 211.

Another particularity is that the failsafe mechanism of not fully closing the fluid path through second inlet 209 and radial channels 210 could be adjusted to integrate another additional circuit, as follows: both piston 203 and valve seat 201 will be made longer. Below second inlet 209 other ports could be integrated as to create a connection between them and outlet 211, so that when the pair formed by the second inlet 209 and radial channel 210 is closed, the new port is opened.

Mounting the valve cartridge according to the invention is carried out in a simplified manner, the preassembled valve cartridge is inserted between suction valve 24, low-pressure accumulator 20 and electronic shuttle valve into a bore of the valve block particularly drilled as to accommodate it through the bottom of the low-pressure accumulator(replacing the prior art's pressure retention valve).

The obtained valve cartridge is cheap, because the low number of components (seven) are manufactured as follows: one turned part; two compression springs; one deep-drawn part; one standard retaining ring; one ball; one plastic casting part. Optional, a standard Ο-Ring (a sealing) is inserted between valve seat 201 and pressure regulating piston 203.

While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.

List of	reference signs
10	Reservoir
11	Tandem master cylinder
12	Pedal
13	Brake line
14	Separating valve
15	Electronically operated inlet valve
16	Wheel brake
17	Supply line
18	Electronic shuttle valve
19	Electronically operated outlet valve
20	Low pressure accumulator
21	Pressure relief line
22	Pump
23	Prior art pressure retention valve
24	Prior art suction valve
25	Pressure valve
26	Damping chamber
27	Throttling orifice
200	Valve cartridge
201	Valve seat
202	Pressure regulation spring
203	Piston
204	Ball
205	Suction spring
206	Spring pot
207	Retaining ring
208	First inlet port
209	Second inlet port
210	Radial channel
211	Outlet port
217	Extended ears
222	Abutment ridge
224	Cone

s Chamfers g Groove h Piston stroke

Claims

1. A valve cartridge (200) for anti-locking brake systems of motor vehicles, characterized by that the valve cartridge (200) comprises:

- an elongated valve seat (201) provided with a first inlet (208) at a first pressure (pl) , a second inlet (209) at a second pressure (p2) , and an outlet (211) at a third pressure (p3),

- a pressure regulation spring (202),

- a piston (203) provided with radial channels (210), and having a stroke (h),

- a ball (204) placed against a cone (224)

- a suction spring (205) supported by a spring pot (206), whereby the stroke (h) of the piston (203) is limited by a retaining ring (207) on one side and on the other by chamfers (s) , the position of the retaining ring (207) on the valve seat (201) corresponds to a full alignment of the radial channels (210) with the second inlet port (209) , in such a manner that it opens a fluid path from the second inlet (209) towards the outlet (211), pressure rising in second inlet (209) causes the piston (203) to rise and decreases the volume of fluid transferred between the second inlet(209) and the radial channels (210) of the piston (203) , gradually balancing the fluid pressures (p2, p3) .

2. Valve cartridge according to claim 1, characterized by that the subassembly comprised of piston (203) , spring pot (206) , ball (204) , and suction spring (205) performs the function of pressure retention, allowing the low pressure accumulator (20) to store pressurized fluid and release it after a certain pressure is achieved at first inlet (208).

3. Valve cartridge according to claim 1, characterized by that the retaining ring (207) is placed on a groove (g) provided on the inner side of a valve seat (201) .

4. Valve cartridge according to claim 1, characterized by that the retaining ring (207) is partially encircling an inner wider section of the valve seat(201), being provided with extended ears (217) as to reduce diameter for assembly, but also to ensure a solid base for the piston (203).

5. Valve cartridge according to claim 1, characterized by that the elongated valve seat (201) is profiled with a continuous inner axial channel as to accommodate the rest of components (202, 203, 204, 205, 206, 207) between the first inlet port (208) and the outlet port (211) .

6. Valve cartridge according to preceding claims, characterized by that radial channels (210) can be connected to additional hydraulic lines as to ensure a failsafe mechanism.

7. A valve block containing the valve cartridge according to claims 1 to 6, characterized by that it has a corresponding profiled bore as to be able to accommodate the valve cartridge (200) .

8. An electronically operated hydraulic brake system comprising a low pressure accumulator (20), a pump (22) and a tandem master cylinder (11), characterized by that contains the valve block according to claim 6, wherein the valve cartridge (200) controls the brake flow between the low-pressure accumulator (20) at the first inlet port (208), the tandem master cylinder (11) at the second inlet port (209) , and at the suction side of pump (22) at the outlet port (211).

Amendments to the claims have been filed as follows:

08 11 18

Patent claims

1. A valve cartridge (200) for anti-locking brake systems of motor vehicles,

5 the valve cartridge (200) comprises:

- an elongated valve seat (201) provided with a first inlet (208) at a first pressure (pl), a second inlet (209) at a second pressure (p2), and an outlet (211) at a third pressure (p3) ,

10 - a pressure regulation spring (202),

- a piston (203) provided with radial channels (210), and having a stroke (h),

- a ball (204) placed against a cone (224)

- a suction spring (205) supported by a spring pot (206),

15 characterized by that the stroke (h) of the piston (203) is limited by a retaining ring (207) partially encircling an inner wider section of the valve seat(201) and provided with extended ears (217), whereby the position of the retaining ring (207) on the valve seat 20 (201) corresponds to a full alignment of the radial channels (210) with the second inlet port (209).