DE102014220627A1 - Hydraulic assembly and brake system - Google Patents

Abstract

Hydraulic assembly having a connecting line (230), in which an inlet valve (234) is connected, wherein parallel to the inlet valve (234), a hydraulic return line (240) is connected, in which a check valve (244) is arranged, which has a flow in one Blocking direction locks in the reverse direction allowed, with the inlet valve (234), a protective check valve (260) is connected in series, which blocks a flow in a direction opposite to the reverse direction of protection and allowed in the reverse direction.

Description

The invention relates to a hydraulic assembly with a connecting line, in which an inlet valve is connected, wherein parallel to the inlet valve, a hydraulic return line is connected, in which a check valve is arranged, which blocks a volume flow in a reverse direction in the reverse direction. It further relates to a brake system for a motor vehicle.

In modern brake systems, in particular electro-hydraulic brake systems with the "brake-by-wire" mode, the driver is decoupled from the direct access to the brakes. Upon actuation of the pedal usually a pedal decoupling unit and a simulator are operated, which is detected by a sensor, the braking request of the driver. The pedal simulator, which is usually designed as a master brake cylinder, serves to give the driver as familiar and comfortable a brake pedal feel as possible. The detected braking request leads to the determination of a desired braking torque, from which then the target brake pressure for the brakes is determined. The brake pressure is then actively built up by a pressure-providing device in the brakes. The actual braking thus takes place by active pressure build-up in the brake circuits with the aid of a pressure supply device, which is controlled by a control and regulation unit. As a result of the hydraulic decoupling of the brake pedal actuation from the pressure build-up, many functionalities such as ABS, ESC, TCS, hill-start assist etc. can be comfortably realized for the driver in such brake systems.

In such brake systems, there is usually provided a hydraulic fallback level by which the driver can decelerate or stop the vehicle by muscular force upon actuation of the brake pedal when the "by-wire" mode fails or is disturbed. While in normal operation by a pedal decoupling unit, the above-described hydraulic decoupling between brake pedal operation and brake pressure build-up, this decoupling is canceled in the fallback so that the driver can move brake means directly into the brake circuits.

The pressure supply device in brake systems described above is also referred to as an actuator or hydraulic actuator. In particular, actuators are designed as linear actuators or linear units in which a piston is axially displaced into a hydraulic pressure chamber for pressure build-up, which is built in series with a rotational-translation gear.

The brake fluid flowing in a brake system described above can be contaminated over time, for example, by small metal chips that dissolve from the installed components. If these contaminants get into switching valves, this can cause them to no longer switch precisely, as a result of which the functionality of the brake system or of the brake system can be impaired. Usually therefore filters are used, which are arranged in the flow direction of the brake fluid in front of a valve, so that the contaminants do not reach the valve.

In known brake systems, a filter is therefore also connected in the hydraulic connection of the master cylinder or tandem master cylinder and the simulator inlet valve.

The volume flow of the brake fluid flowing from the master cylinder in the simulator, however, can become so high, in particular during full braking, that the filter can be damaged or destroyed. Also in other hydraulic applications where an inlet valve is used, the inlet valve should be protected from contamination. In the context of this application, the term inlet valve is understood to mean any hydraulic valve which can act as an inlet, passage or outlet valve.

The invention is therefore based on the object to provide a hydraulic assembly in which the inlet valve is protected from contamination and damage and at the same time high volume flows are possible. Furthermore, a brake system is to be provided in which the function of the simulator inlet valve is not impaired by contamination.

With respect to the hydraulic assembly, this object is achieved in that is connected to the inlet valve, a protective check valve in series, which blocks a flow in a reverse direction opposite to the direction of protection and allowed in the reverse direction.

Advantageous embodiments of the invention are the subject of the dependent claims.

The invention is based on the consideration that due to the high volume flows that can occur between master cylinder and simulator and the possible possible destruction of the filter an alternative design measure should be found, since the contamination of the valve should be prevented in any case. A mere enlargement or amplification of the filter is due to space engineering, material technology and cost considerations out of the question.

As has now been recognized, this measure can be realized by placing a protective check valve in a described hydraulic circuit, which is used for example in a brake system, which allows a flow in a direction of protection from the master cylinder through the simulator inlet valve into the simulator and vice versa Direction, so from the simulator through this valve locks. This construction reliably prevents brake fluid from flowing from the direction of the simulator into or through the simulator inlet valve, so that no contamination in this direction can also enter the valve.

A backflow of liquid from the simulator in the direction of the master cylinder is still possible despite this blocking due to the parallel-connected return line.

Advantageously, the protective check valve is arranged in the direction of protection before the inlet valve. In this configuration, it effectively replaces a conventional filter located at this point. However, the invention also includes configurations in which a filter is connected in series with the protective check valve.

In another embodiment, the protective check valve is preferably arranged in the direction of protection behind the inlet valve. Also on this side, it protects the simulator inlet valve from soiling due to its blocking effect.

In a preferred embodiment, a filter is hydraulically connected in parallel to the protective check valve. As a result, the volume flow divides into a first portion, which flows through the check valve, and a second portion, which flows through the filter. This reduces the load on the filter, and due to the reduced flow through the check valve, this need not be increased to have a sufficiently small flow resistance.

The parallel connection of check valve and filter is structurally preferably implemented in an assembly, which is preferably pre-assembled in a housing and is easy to install in this way in the brake system.

In a first preferred embodiment, the inlet valve and in the axial direction adjacent to the valve seat in a receiving bore of the filter are arranged in a common housing, wherein the filter is pressed by an elastic member against the valve seat and thereby closes a gap through which hydraulic in the open state Liquid flows past the filter.

In a second preferred embodiment, the inlet valve and the filter are arranged in a common housing, wherein the filter on the side facing away from the valve has a sealing seat against which a closing element is pressed by an elastic element, which opens a flow path for hydraulic fluid in the open state. The closing element closes the filter outlet, whereby a sealing seat is formed on the filter.

The closing element is preferably designed as a steel ball, which is pressed by the elastic element against the filter.

The closing element can also be designed as a closure pin, which serves as a guide for the elastic element, which is designed as a compression spring and is partially guided around the elastic element.

The inlet valve is preferably designed as a normally closed valve.

With respect to the brake system, the above object is achieved with a brake system for a motor vehicle, comprising a master cylinder, which is hydraulically connected to at least one brake circuit, with a pressure supply device for the active pressure build-up of brake pressure in the at least one brake circuit connected brakes and with a simulator which is separably connected to the master cylinder via a hydraulic simulator connection line, in which a hydraulic assembly described above is hydraulically connected. The inlet valve acts as a simulator inlet valve.

Particularly preferably, the brake system is constructed with two circuits, wherein each brake circuit are each assigned two wheel brakes. The distribution of the brakes on the brake circuits can be black-white or diagonal.

Between simulator inlet valve and simulator, no filter is preferably connected in series with the check valve.

On the simulator side facing away from the Simulatoreinlassventils a filter is preferably arranged.

The advantages of the invention are in particular that the function of a filter can be taken over by the in-series switching of a check valve with the Simulatoreinlassventil, which blocks the flow of brake fluid from the simulator through the valve, wherein the hydraulic assembly or circuit high Volumetric flows withstand, so that their reliability and lifetime are increased.

The hydraulic circuit is not limited to applications in a brake system described. It can also be used, for example, in single-circuit brake systems or other hydraulic systems in which a valve is to be protected against contamination in a flow direction.

An embodiment of the invention will be explained in more detail with reference to a drawing. In it show in a highly schematic representation:

1 a hydraulic circuit diagram of an electro-hydraulic brake system according to the prior art,

2 FIG. 2 shows a hydraulic circuit diagram of an electrohydraulic brake system with a hydraulic assembly in a preferred embodiment, FIG.

3 a hydraulic circuit diagram of an alternative embodiment of the hydraulic assembly,

4 a hydraulic circuit diagram of a further alternative embodiment of the hydraulic assembly,

5 3 a perspective view of a hydraulic assembly with a valve and a filter in a first variant,

6 a perspective view of a hydraulic assembly with a valve and a filter in a second variant with a closing element, and

7 a perspective view of a filter and a closing element in an alternative embodiment.

Identical parts are provided with the same reference numerals in all figures.

The in the 1 illustrated exemplary electro-hydraulic brake system 2 The prior art includes a tandem master cylinder 6 , a simulation device 10 , an electrically controllable pressure supply device 14 , a wheel brake pressure modulation device 16 and an electronic control unit (ECU) 18 , To the wheel brake pressure modulation device 14 are wheel brakes 22 . 26 . 30 . 34 connected. The wheel brake 22 is the left front wheel 40 , the wheel brake 26 the right rear wheel 44 , the wheel brake 30 the right front wheel 48 and the wheel brake 34 the left rear wheel 52 assigned. The brake system 2 has a diagonal distribution: wheel brakes 22 . 26 (front left, rear right) are with a first brake circuit I , Wheel brakes 30 . 34 (front right, rear left) with a second brake circuit II hydraulically connected.

The tandem master cylinder 6 that of a brake pedal 56 is actuated, has two pressure chambers 60 . 64 on. The pressure chambers 60 . 64 of the tandem master cylinder 6 are with a pressure medium reservoir under atmospheric pressure 68 (preferred with fully released brake pedal 56 ) connectable.

The actuating travel of the brake pedal 56 is by means of a preferably redundant displacement sensor 72 recorded, the z. B. the way of a piston 76 senses and thus the driver request recognition or a setpoint generation in the electronic control unit 18 serves and performs the function of a detection element for detecting the braking request of the driver.

The electrohydraulic pressure supply device 14 essentially comprises a hydraulic cylinder-piston arrangement 80 and an electromechanical actuator 84 that by an electric motor 88 is formed with a reduction gear, which is a rotational movement of the electric motor 88 in a translational movement of a hydraulic piston 92 so that in a pressure room 96 the hydraulic cylinder-piston arrangement 80 a hydraulic pressure is built up. The electromechanical actuator 84 is powered from the electrical system (not shown) of the vehicle, optionally buffered by an electrical energy storage (not shown) with energy. The movement of the piston 92 is indirectly by means of a rotation angle sensor 100 detects the rotor position of the electromechanical actuator 44 sensed, and a redundant displacement sensor 104 , which senses the traveled piston travel detected.

The pressure room 96 is via a hydraulic line 110 and normally closed isolation valves 114 . 116 with the brake circuits I . II connectable.

In normal operation of the brake system 2 ("Brake-by-wire" mode) builds the electromechanical-hydraulic actuator 84 the system brake pressure from which the Radbremsdruckmodulationseinrichtung 14 generates wheel-specific brake pressures. A wheel brake pressure build-up occurs in normal operation - with each wheel brake 22 . 26 . 30 . 34 - Each with an open, normally closed analog intake valve 120 . 124 . 128 . 132 , A Radbremsdruckabbau done either via a backflow through the normally closed analog intake valve 120 . 124 . 128 . 132 , in principle, in this flow direction no analog valve control, but only a complete opening is possible, so that such a pressure reduction at all open normally closed valves 120 . 124 . 128 . 132 occurs simultaneously, or - if a wheel individual pressure reduction is needed - on one of the respective wheel brake 22 . 26 . 30 . 34 each associated normally open analogous outlet valve 140 . 144 . 148 . 152 ,

Via a redundant pressure sensor 160 can the brake pressure in the brake fluid line 110 that the pressure room 96 with the brake circuits I . II connects, be measured. Via a redundant pressure sensor 162 can the brake pressure in a brake fluid line 164 be measured.

The pressure chambers 60 . 64 of the tandem master cylinder 6 are each a normally open isolation valve 166 . 170 with the brake circuits I . II connected or connectable.

In a fallback mode of operation, the two circles of the tandem master cylinder 6 (via the open isolation valves 166 . 170 ) with the brake circuits I . II connected. To avoid a compression of these valves in pedal-controlled pressure build-up check valves are connected in parallel. To claim the fallback mode of operation any energization of the valves and the actuator are turned off in the exemplary brake system. Due to the connection of each wheel brake 22 . 26 . 30 . 34 with one of the two chambers or pressure chambers 60 . 64 of the tandem master cylinder 6 In this operating mode, two brake circuits are separated from one another hydraulically I and II made, which ensures that the vehicle in the fallback mode or in the fallback mode by all wheel brakes 22 . 26 . 30 . 34 can be braked and sufficient braking torque can be built even if one of the two brake circuits I . II fails.

A switching of the modulator or the Radbremsdruckmodulationseinrichtung 14 from the fallback mode to normal operation is carried out by energizing the isolation valves 114 . 116 . 166 . 170 ,

In the said normal operating mode of the brake system 2 ("Brake-by-wire" mode) is the tandem master cylinder 6 by means of isolation valves 166 . 170 from the wheel brakes 22 . 26 . 30 . 34 or the brake circuits I . II decoupled, and pressure medium is by the driver from the two pressure chambers 60 . 64 of the tandem master cylinder 6 into the simulation device 10 shifted, which gives the driver a familiar and pleasant pedal feel. The brake pressure at the wheel brakes 22 . 26 . 30 . 34 is through the pressure delivery device 16 provided.

The simulation device 10 represents a hydraulically actuated pedal feel simulator. It includes, for example, an elastic element 180 (eg a simulator spring) and a piston 184 which is a boundary of a hydraulic room 188 represents.

In normal operation of the brake system are hydraulic connections from the tandem master cylinder 6 to the wheel brakes 22 . 26 . 30 . 34 through the isolation valves 13a . 13b locked while the simulator is unlocked. In a fallback mode, the tandem master cylinder is 4 connected to the wheel brakes and the simulator is locked.

The pressure room 96 the pressure supply device 14 is via a hydraulic line 190 into which a check valve 194 is switched, with the brake fluid reservoir 68 connected. Via a hydraulic line 198 is the pressure room 60 with the brake fluid reservoir 68 connectable. The pressure room 64 is via a hydraulic line 200 into which a switching valve 204 switched, connectable. On both sides of the switching valve 204 is each a filter 208 . 210 arranged. Parallel to the switching valve 204 is a hydraulic bypass line 218 with a check valve connected therein 220 arranged.

So in the normal mode when pressing the brake pedal 56 Brake fluid from the tandem master cylinder 6 in the simulator 10 is promoted, connects a hydraulic line 230 which also leads from a node A to a node B, the pressure chamber 64 of the tandem master cylinder 6 with the pressure chamber 188 of the simulator 10 , Into the line 230 is a normally closed simulator inlet valve 234 switched, which is opened in normal operation. Parallel to the simulator inlet valve 234 is in a hydraulic bypass line 240 passing between nodes A and B, a check valve 244 connected, which a volume flow from the pressure chamber 188 of the simulator towards tandem master cylinder 6 allowed and locks in the opposite direction. Brake fluid flows from the tandem master cylinder 6 in the simulator 10 always through the simulator inlet valve 234 ,

On both sides of the simulator inlet valve 234 , ie between simulator inlet valve 234 and simulator 10 as well as between simulator inlet valve 234 and tandem master cylinder 6 , is a filter 250 . 254 arranged. Through the respective filter 250 . 254 prevents soiling that are in the brake fluid, in the simulator inlet valve 234 reach. Such contamination can be, for example, metal chips or abrasion from the components installed in the brake system, through which brake fluid flows. If these contaminants get into the valve, it may no longer be able to close correctly or completely so that the functionality of the brake system can be impaired.

The problem with such an arrangement of the filter 254 that is between simulator inlet valve 234 and pressure chamber 188 or simulator 10 is arranged, however, is that with strong braking the volumetric flow through the filter 244 can become so large that the flow forces occurring the filter 244 to destroy.

A brake system 2 in a preferred embodiment, wherein the simulator inlet valve 244 continues to be protected against contamination and in which the substantially same hydraulic function is realized between the node A and B, is in 2 shown. The brake system 2 according to 2 is with the in 1 Same as the hydraulic assembly between the points A and B. The filter 254 is with this brake system 2 through a check valve 260 replaced, which volume flow from node B to node A through the switching valve or simulator inlet valve 234 prevents and thereby protects this valve from contamination. A volume flow from node B to A is always allowed by the parallel check valve 244 , A volume flow from A to B is only possible with the simulator inlet valve open 234 allowed, especially during the normal mode of the brake system in brake-by-wire mode. The filter 250 and the valve 234 can preferably be formed as a preassembled or preassembled module, which by a dashed box 280 is clarified. From A to B, a reverse direction of the check valve runs 244 and a protective direction of the check valve 260 or protective check valve.

In 3 is a further preferred embodiment of a hydraulic assembly shown. This is between the nodes A and B in the brake system 2 according to 2 integrated and replaced the corresponding in 2 shown assembly. In this embodiment are opposite to in 2 shown embodiment, the Simulatoreinlassventil 234 and the check valve 260 reversed. A volume flow from the simulator 10 in the direction of the tandem master cylinder 6 through the valve 234 is reliably prevented by the check valve even in this configuration.

In 4 is a further preferred embodiment of a hydraulic assembly shown. In this embodiment is to the check valve 260 in a hydraulic line 282 a filter 284 connected in parallel. A high volume flow from A to B flows partly through the filter 284 and partly by the parallel check valve 260 , This firstly becomes the filter 284 not overloaded. Second, the flow resistance of the check valve 260 be increased with the same total resistance, especially in comparison to the previous versions. In the in the 2 and 3 the embodiments shown must namely the check valve 260 be large enough to have a sufficiently small flow resistance.

In 5 a hydraulic assembly is shown in a first preferred embodiment, the hydraulic circuit diagram of 4 corresponds, in which the check valve and filter are connected in parallel. In a housing 300 are in an axial direction 302 seen the normally closed (SG) simulator inlet valve 234 which is a valve body 304 and a valve element displaceable therein 308 and at its sealing seat 306 the filter 284 arranged. The filter 284 sits in a receiving hole under the SG valve 234 , The top of the filter 284 is pressed by the given installation space in the axial direction against the valve body. Due to the installation space results in the axial direction an excess, through which the filter ensures the sealing effect of the filter support against the valve body. This sealing effect prevents dirt particles from entering the interior of the filter carrier.

The function of the circuit diagram according to 4 is achieved by the filter by a spring against the sealing seat 306 is pressed. Due to the bias of the spring is the sealing seat 306 locked. If at a high flow, which is generated by the rapid actuation in, the back pressure above the filter fabric is higher than the spring preload, the filter body from the sealing seat 306 lifted off to the valve. For lifting to be possible, the illustrated clearance must be provided. At this moment, the brake fluid can through a now open gap 320 around the filter 284 flow around. The high volume flow therefore produces no further increase in the ram pressure above the filter cloth, which could destroy it. The overpressure function is therefore shown in the filter body with an additional spring. Likewise, the dirt chamber is avoided during assembly between the filter and solenoid valve.

The check valve 260 is thus realized by the fact that the filter 284 with the aid of a designed as a compression spring elastic element 316 against the valve seat 306 is pressed. A clearance is realized through a gap 320 in the normal state, ie when there is little or no brake fluid through the valve 234 flows, is closed, so brake fluid only through the filter 284 flows. The elastic element 316 or the compression spring is designed such that when exceeding a predetermined pressure or upon reaching a predetermined flow rate of the filter 284 lifts off the valve seat, leaving the gap 320 is released and the brake fluid can flow through this gap and the filter immediately. A flow in the reverse direction is avoided due to this construction, so that the functionality of a check valve is given.

In 6 an alternative version of the module is shown, whose functionality again according to the wiring diagram 4 corresponds, but through an additional sealing seat in a filter body 324 of the filter 284 is pictured. This is the filter body 324 used as a pressure relief valve. He just becomes a tight seat 328 extended. The seal seat 328 is through a closing element 330 , which is presently designed as a steel ball, in the normal state, ie when the flow velocity of the brake fluid falls below a predetermined threshold, closed and is by a separate spring (elastic member 316 ) and a carrier 332 against the seal seat 328 pressed. Functionally, it is also avoided that dirt particles between filter during the assembly process 284 and solenoid valve seat can be chambered.

Alternatively to the ball sealing seat, as in 7 shown as a closing element 330 also a plastic element 340 be used in the leadership of the spring by the closing element 330 self-assured. By a symmetrical design, the directional installation can be prevented.

LIST OF REFERENCE NUMBERS

2

 electrohydraulic brake system

6

 Tandem master cylinder

10

 Simulation device / simulator

13a, 13b

 isolation valve

14

 controllable pressure delivery device

16

 Radbremsdruckmodulationseinrichtung

18

 electronic control unit (ECU)

22, 26, 30, 34

 wheel brakes

40

 left front wheel

44

 right rear wheel

48

 right front wheel

52

 left rear wheel

56

 brake pedal

60, 64

Pressure chambers of the tandem master cylinder 6

68

 Pressure fluid reservoir

72

 displacement sensor

76

 piston

80

 hydraulic cylinder-piston arrangement

84

 electromechanical actuator

88

 electric motor

92

 hydraulic piston

96

 pressure chamber

100

 Rotation angle sensor

104

 displacement sensor

110

 hydraulic line

114, 116

 isolation valve

120, 124, 128, 132

 normally closed analogue inlet valve

140, 144, 148, 152

 normally open analogue outlet valve

160

 pressure sensor

162

 pressure sensor

164

 brake fluid line

166, 170

 normally open release valve

180

 elastic element

184

 piston

188

 hydraulic room

190

 hydraulic line

194

 check valve

198

 hydraulic line

200

 hydraulic line

204

 switching valve

208, 210

 filter

218

 hydraulic bypass

220

 check valve

230

 management

234

 Simulator inlet valve

240

 hydraulic bypass

244

 check valve

250, 254

 filter

260

 check valve

280

 box

284

 filter

300

 casing

302

 axially

304

 valve body

306

 sealing seat

308

 valve element

316

 elastic element

320

 gap

324

 filter body

328

 sealing seat

330

 closing element

A, B

 junction

I

 first brake circuit

II

 second brake circuit

Claims (10)

Hydraulic assembly with a connecting line ( 230 ) into which an inlet valve ( 234 ), wherein parallel to the inlet valve ( 234 ) a hydraulic return line ( 240 ), in which a check valve ( 244 ) Is arranged, which blocks a flow in a reverse direction in the reverse direction allowed, characterized in that (with the intake valve 234 ) a protective check valve ( 260 ) is connected in series, which blocks a flow in a direction opposite to the reverse direction of protection and allowed in the reverse direction. Hydraulic assembly according to claim 1, wherein the protective check valve ( 260 ) seen in the protective direction in front of the inlet valve ( 234 ) is arranged. Hydraulic assembly according to claim 1, wherein the protective check valve ( 260 ) seen in the protective direction behind the inlet valve ( 234 ) is arranged. Hydraulic assembly according to one of claims 1 to 3, wherein the protective check valve ( 260 ) a filter ( 284 ) is connected in parallel hydraulically. Hydraulic assembly according to claim 4, wherein in a common housing ( 306 ) the inlet valve ( 234 ) and in the axial direction adjacent to the valve seat ( 306 ) in a receiving bore of the filter ( 284 ) are arranged, wherein the filter ( 284 ) by an elastic element ( 316 ) against the valve seat ( 306 ) is pressed while a gap ( 320 ), by the hydraulic fluid in the opened state on the filter ( 284 ) flows by. Hydraulic assembly according to claim 4, wherein in a common housing ( 300 ) the inlet valve ( 234 ) and the filter ( 284 ) are arranged, wherein the filter ( 284 ) on the ventilabgewandten side a sealing seat ( 328 ), against which by a resilient element a closing element ( 330 ) is pressed, which releases a flow path for hydraulic fluid in the open state. Hydraulic assembly according to claim 6, wherein the closing element ( 330 ) is designed as a steel ball. Hydraulic assembly according to claim 6, wherein the closing element ( 330 ) as a plug ( 340 ) is formed, which serves as a guide for the elastic element, which is designed as a compression spring and is partially guided around the elastic element. Brake system ( 2 ) for a motor vehicle, comprising a master cylinder ( 6 ), which is hydraulically connected to at least one brake circuit ( I . II ) is detachably connected to a pressure supply device ( 14 ) for the active pressure build-up of brake pressure in the brakes connected to the at least one brake circuit ( 22 . 26 . 30 . 34 ) and with a simulator ( 10 ), which is connected to the master cylinder ( 6 ) via a hydraulic simulator connection line ( 230 ) is separably connected, in which a hydraulic assembly according to one of claims 1 to 9 is hydraulically connected. Brake system according to claim 9, wherein between inlet valve ( 234 ) and simulator ( 10 ) no filter is connected in series.

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