DE102017203952A1 - Vehicle brake system with a pedal-operated master cylinder - Google Patents

Abstract

A vehicle brake system has both a master cylinder (1) and a third party pressure transducer. By switching valves (14, 34) either the master cylinder (1) or the external pressure transducer to the wheel brakes (6, 7) is connected, in the second case the master cylinder (1) is hydraulically locked by the brake circuits and to realize a pedal feel with a Bremswegsimulator (15) is connected.
The pressure control in the wheel brakes (6, 7) via inlet and outlet valves (8, 9, 10, 11), wherein the set pressure is determined by the pedal travel, which is measured for this purpose and is supplied as a control variable of a control.
In previous embodiments of the system, the switching valve (14, 34), which implements the switching between the master cylinder (1) and the external pressure transducer, carried out by two solenoid valves, so that four additional electromagnetic valves were necessary. Also, the connection of the pedal travel simulator was carried out via an electromagnetically actuated valve.
In the present case, the invention provides that the switching valves (14, 34) and possibly the simulator valve (17) are hydraulically actuated valves, which are switched by the differential pressure between the master cylinder (1) and the external pressure transducer.

Description

The invention relates to a vehicle brake system with a pedal-operated master cylinder, a third-party pressure transducer and a Bremswegsimulator, and with wheel brakes, of which at least one via a branching brake line, in the common section a normally closed electromagnetically actuated exhaust valve is arranged, both with the master cylinder is also connectable to the external pressure transducer and a pressure relief line, which has a normally closed electromagnetically actuated outlet valve, with a Druckmittelsenke connectable, and with a switching valve in the branch point of the brake pipe, depending on its switching position the master cylinder, the external pressure transducer or both with the at least connects a wheel brake, and with a simulator valve that connects the master cylinder with the Bremswegsimulator.

Such a plant is in the DE 10 213 216 314 A1 shown. The switching valve is represented by two electromagnetically operable valves, wherein the one valve is a normally open valve, which is the connection to the master cylinder and the second valve is a normally closed valve, which is the connection to a pressure transducer. The external pressure transducer is in this case a motor-driven reciprocating piston, which displaces pressure medium from a storage chamber.

In principle, as described below in the invention, pumps can also be used instead of such an external pressure generator.
The electromagnetically actuated valves are generally combined into a so-called valve block, which are arranged for practical reasons so that the coils of the actuating magnets are all arranged on one side of the valve block, so that they can be accommodated in a control unit, which on the Valve block is slipped.

In the case of the multiplicity of valves, this can not be achieved in the same way and as a rule leads to a relatively complicated construction of the valve block so that the required connections between the valves can be produced therein.

The invention is therefore based on the task of simplifying the construction of the valve block and generally to achieve a more compact structure.

To achieve the object, the invention provides that each switching valve is an exclusively hydraulically actuated valve, wherein the control of the switching valve is effected by the differential pressure between the master cylinder and the brake pressure generator.

Compared to the embodiment according to the prior art 4 solenoid valves are thereby saved, whereby the valve block can be constructed much more compact and the control is simplified.

The structure can be further simplified if the simulator valve is realized exclusively as a hydraulically actuated valve.

The switching valves can be realized so that only either the master cylinder or the external pressure transducer is connected to the wheel brakes. But it can also be made a setting that they can additionally occupy a middle position in which both the master cylinder and the external pressure transducer are connected to the wheel brakes.

In this case, the simulator valve is preferably integrated in the switching valve of the brake circuit, which is connected to the pedal pressure chamber.

A switching valve is preferably realized in that a stepped piston is provided, the two end faces are loaded by the pressure of the master cylinder and the pressure of the external pressure transducer, wherein depending on the achieved thereby position of the stepped piston either the one or the other connection is open.

In order to integrate the simulator valve, a further valve piston is provided, which is mechanically actuated by the stepped piston. This ensures that a connection of the master cylinder to the brake pressure simulator is present only when the connection of the master cylinder is locked to the wheel brakes and the pressure medium supply of the wheel brakes via the external pressure transducer.

In a dual-circuit brake system with wheel brakes in each brake circuit, the invention preferably provides that the wheel brakes of at least one brake circuit via a branching brake line, in the common section a normally closed electromagnetically actuated inlet valve is arranged, both with the master cylinder and with the external pressure transducer and via a pressure relief line, which has a normally closed electromagnetically actuated outlet valve, with a pressure medium sink are connectable.

The brake system also has a switching valve in the branch point of the brake line of the respective brake circuit, depending on his Shift position the master cylinder, the external pressure transducer or both connects to the at least one wheel brake, and further includes a simulator valve which connects the pedal pressure chamber with the Bremswegsimulator.

In this case, the master cylinder to a pedal piston and a floating piston having tandem master cylinder, wherein the Bremswegsimulator is connected to the lying between the pedal piston and the floating piston pedal pressure chamber of the tandem master cylinder.

The simulator valve is integrated in the switching valve of the brake circuit, which is connected to the pedal pressure chamber.

The switching valve has four ports, two switching positions and a middle position, in which the wheel brake is connected to both the master cylinder and the external pressure transducer.

• 1 einen hydraulischen Schaltplan einer ersten Ausführung einer erfindungsgemäßen Fahrzeugbremsanlage mit zwei Bremskreisen und mit einem Pedalwegsimulator an einem der Bremskreise,
• 2 den Querschnitt durch ein hydraulisch betätigtes Schaltventil für eine Fahrzeugbremsanlage nach 1 um die Verbindung zwischen Radbremsen einerseits und einem Hauptbremszylinder und einem Fremdruckgeber andererseits,
• 3 einen hydraulischen Schaltplan einer zweiten Ausführung einer erfindungsgemäßen Fahrzeugbremsanlage, bei der ein modifiziertes Schaltventil auch die Verbindung zu dem Pedalwegsimulator steuert,
• 4 den Querschnitt durch ein modifiziertes Schaltventil, das für den Bremskreis mit dem Pedalwegsimulator benötigt wird,
• 5 eine dritte Ausführung der erfindungsgemäßen Bremsanlage, bei der die beiden Bremskreise getrennt betätigbare Fremddruckquellen aufweisen und
• 6 eine vierte Ausführung der erfindungsgemäßen Bremsanlage.

In the following, the invention will be explained in more detail with reference to four embodiments. To show:

• 1 3 is a hydraulic circuit diagram of a first embodiment of a vehicle brake system according to the invention with two brake circuits and with a pedal travel simulator on one of the brake circuits;
• 2 the cross section through a hydraulically actuated switching valve for a vehicle brake after 1 to the connection between wheel brakes on the one hand and a master cylinder and a Fremdruckgeber other hand,
• 3 2 a hydraulic circuit diagram of a second embodiment of a vehicle brake system according to the invention, in which a modified switching valve also controls the connection to the pedal travel simulator,
• 4 the cross section through a modified switching valve, which is needed for the brake circuit with the pedal travel simulator,
• 5 a third embodiment of the brake system according to the invention, in which the two brake circuits have separately operable external pressure sources and
• 6 a fourth embodiment of the brake system according to the invention.

The following is based on the 1 First, the basic structure of the brake system will be described. This applies, as far as nothing else is executed, also for the explanations after the 3 . 5 and 6 ,

The brake system has a pedal-operated master cylinder 1, which is designed in this embodiment as a tandem master cylinder. This has a pedal-operated pedal piston 2 and a floating piston 3 , which are arranged one behind the other in a brake cylinder having a bottom.

Between the pedal piston 2 and the floating piston 3 is the pedal chamber 4 , between the floating piston and the bottom of the cylinder is the floating chamber 5 , The two chambers 4 and 5 are connected to a respective brake circuit. Each brake circuit has two arranged in respective vehicle wheels wheel brakes 6 . 7 , each via a normally open electromagnetically actuated inlet valve 8th . 9 with the associated chamber 4 . 5 in the master cylinder 1 are connected. The wheel brakes 6 . 7 are still about exhaust valves 10 . 11 with a storage container 12 connected to the master cylinder 1 is arranged and its chambers 5 . 6 hydraulic connection has, as long as the master cylinder 1 not pedal operated.

By means of the connection and exhaust valves 8th . 9 . 10 . 11 can the pressure in the wheel brakes 6 . 7 be slipped. As soon as it is determined by corresponding sensors that one of the wheels threatens to block, the associated inlet valve 8th . 9 closed and the associated exhaust valve 11 . 12 open, allowing pressure fluid in the reservoir 12 can drain away. For a new pressure build-up, the two valves are switched again, both valves are closed to maintain pressure.

This procedure is well known and will not be explained in detail here.

A corresponding regulation can also be made in order to set a brake pressure in all wheel brakes, with which a braking deceleration desired by the vehicle driver occurs. This type of regulation is needed when next to the master cylinder 1 an external pressure source is present, which is connected instead of the master cylinder to the respective brake circuit. In the present embodiment, the external pressure source is in each case a motor-driven pump 13 for each brake circuit. To both the master cylinder 1 as well as the pump 13 connect, a branched brake line is provided for both brake circuits, which - starting from the wheel brakes - on the one hand to the master cylinder 1 and the other to the pump 13 branched.

In the common part of the brake line is the respective inlet valve 8th respectively. 9 , In Branch point t is in each case a switching valve 14 , depending on the position of the switching valve 14 either the master cylinder 1 or the pump 13 has a connection to the wheel brakes.

The brake system continues to see a braking distance simulator 15 ago, via a simulator line 16 with the pedal chamber 4 the master cylinder is connected.

According to the execution according to 1 is in this simulator line 16 a simulator valve 17 , which is electromagnetically actuated and is normally closed. Parallel to this is a check valve 18 , which blocks the pedal travel simulator 15 out.

Such a brake system works as follows: A braking is initiated, in which the driver depresses the brake pedal and thus actuates the master cylinder. Pressure medium is released from the pedal chamber 4 and the swimming chamber 5 over the respective brake circuit in the connected wheel brakes 6 . 7 displaced and thus built up a pressure that leads to a vehicle deceleration. Simultaneously with the pedal operation, the motor of the pump 13 switched on, the switching valve 14 is switched, so that now no longer the master cylinder 1 The actual pressure in the wheel brakes is controlled by the inlet and outlet valves.
Because with the switching of the switching valve 14 the master cylinder 1 is hydraulically locked, the pedal would be blocked, so that it can not be passed on. The driver would lose the usual correlation between the pedal travel and the brake pressure leading to the desired vehicle deceleration. Therefore, the simulator valve 17 open, so now the pressure fluid from the pedal chamber 4 in the braking distance simulator 15 is displaced, the piston against a simulator spring package 19 is moved.

Depending on the pedal travel now a retroactive force is exerted on the pedal, the force-displacement characteristic of the spring assembly 19 equivalent.

In this embodiment, the pedal travel is measured and associated with a particular brake pressure, electronically from the controlled intake and exhaust valves 8th . 9 . 10 . 11 is set. Since in this setting the brake circuits pressure fluid is removed, the suction side of the pump 13 via a suction line with the reservoir 12 connected, so that the pressure reduction for the brake circuits taken pressure fluid through the pump 13 can be returned to the brake circuits. If at the set brake pressure a wheel threatens to block, the pressure is no longer determined by the pedal travel, but set slip-controlled.

The brake system also allows a brake pressure build-up in the wheel brakes 6 and 7 regardless of a pedal operation. This can be z. B. for traction control or vehicle dynamics regulations of importance.

As mentioned, each brake circuit has a branching brake line, wherein in each of the two branch points a switching valve 14 is arranged. A possible construction of such a valve is explained in more detail in FIG.

Basically, it is the switching valve 14 according to this embodiment, a 3/2-way valve, that is, it has three ports and two positions. In the first position is the branch of the brake line to the master cylinder 1 opened and the branch to the pump 13 closed. Will the switching valve 14 switched, so is the branch to the master cylinder 1 closed and the pump 14 open.

The valve is controlled by the differential pressure between the pump output pressure and the master cylinder pressure.

• Dieses besteht aus einem stufigen Hohlzylinder 20, dessen Enden jeweils durch eine Stirnwand 21, 22 geschlossen sind. In diesen Stirnwänden 21, 22 befindet sich jeweils ein zentraler Anschluss 23, 24. In dem Hohlzylinder 20 ist ein Stufenkolben 25 geführt.
• Dieser begrenzt mit seinem größeren Durchmesser eine erste Einlasskammer 26 zwischen seiner Stirnfläche und der einen Stirnwand 21. Mit seinem kleineren Durchmesser begrenzt er eine zweite Einlasskammer 27 zwischen seiner Stirnfläche und der zweiten Stirnwand 22.

In the 2 a typical embodiment of such a valve is shown:

• This consists of a stepped hollow cylinder 20 whose ends each through an end wall 21 . 22 are closed. In these end walls 21 . 22 there is in each case a central port 23, 24. In the hollow cylinder 20 is a stepped piston 25 guided.
• This limits with its larger diameter a first inlet chamber 26 between its end face and the one end wall 21 , With its smaller diameter, it limits a second inlet chamber 27 between its end face and the second end wall 22 ,

The boards 23 . 24 are on their insides, which are the respective inlet chamber 26 . 27 facing, provided with a valve seat having a closure body on the respective end face of the stepped piston 25 interacts. A valve spring 28, which is in the second inlet chamber 27 is arranged, presses the stepped piston 25 in a home position where the first port 23 in the first front wall 21 is blocked by the local closure body and the second port 24 in the second end wall 22 is open.
The differential end face 29 at the rear of the section of the larger diameter stepped piston is adjacent to a ventilated space 30 at. To the two inlet chambers 21 . 27 includes each side an outlet 31 respectively. 32 on, which are connected to the wheel brakes of the respective brake circuit. In the outlet 31 , the first inlet chamber 26 , there is a check valve 33 leading to the first inlet chamber 26 locks out.

At the first connection 23 is the one to the pump 13 leading branch of the brake pipe connected to the second port 24 is the master cylinder 1 leading branch of the brake pipe connected. In the illustrated basic position of the switching valve 14 is this last mentioned connection 24 open, allowing a direct connection between the master cylinder 1 and the wheel brakes 6 and 7 consists. Once - as described above - the pump 13 is put into operation, builds up in the first port 23, a pressure acting against the pressure in the second inlet chamber 27 and a displacement of the stepped piston 25 leads. This will be the first connection 23 open so that now the entire diameter of the larger step of the stepped piston 25 is loaded and thus the stepped piston 25 safely holding in a switching position where the first port 23 opened and the second connection 24 closed is. This switching operation can be accelerated if the valve seat in the first outlet is not completely sealed, but also in the basic position of the valve, a pressure build-up in the first inlet chamber 26 allows. That in the 2 described valve is installed in both brake circuits and ensures that when switching on the pump 13 a switching of the switching valves takes place, so that the further brake pressure build-up and adjustment with pressure medium, which is carried by the pump 13 comes.

The switching point of the switching valves 14 is determined by the size ratios of the two stages of the stepped piston 25 the spring characteristic of the valve spring 28 and the permeability of the first port 23 ,

This valve is a brake system according to the 1 used in the simulator valve 17 is electromagnetically actuated.

In the execution after 3 will this simulator valve 17 in one of the switching valves 14 , namely in the switching valve, which connects to the pedal chamber 4 controls, integrates and thus no longer separately electromagnetically, but hydraulically actuated together with this switching valve.

Again 3 can be taken, this is the switching valve 34 a 4/2-way valve, while the switching valve 14 in the other brake circuit is still a 3/2-way valve that can be executed, as shown in the 2 is explained.

The 4 / 2 -Way switching valve 34 has besides the terminals 23 , 24 for the master cylinder 1 and the pump 13 as well as the outlets 31 . 32 to the wheel brakes 6 . 7 another connection 37 leads to the Bremswegsimulator.

• Das dort vorgestellte Schaltventil 34 besitzt einen Grundaufbau, wie er in der 2 dargestellt ist, so dass darauf insoweit Bezug genommen wird.
• An die zweite Stirnseite 22 mit dem zweiten Anschluss 24, der als schließbarer Durchlass fungiert, schließt eine hohlzylindrische Verlängerung 36 einer weiteren Stirnseite 40 an, in dem sich ein dritter Anschluss 41 befindet. Innerhalb dieser Verlängerung befindet sich ein Ventilkolben 42, der über eine Längsbohrung 43 verfügt, so dass unabhängig von der Lage des Ventilkolbens 42 eine ständige Verbindung zwischen dem dritten Anschluss 41 und dem zweiten Anschluss 24 besteht.

One possible construction is in the 4 shown:

• The switching valve presented there 34 has a basic structure, as in the 2 is shown so that reference is made to this extent.
• At the second end 22 with the second connection 24 , which acts as a closable passage closes a hollow cylindrical extension 36 another end face 40 in which there is a third connection 41 located. Within this extension is a valve piston 42 , which has a longitudinal bore 43 has, so that regardless of the position of the valve piston 42 a permanent connection between the third port 41 and the second port 24 consists.

The valve piston 42 separates a third inlet chamber 44 with a lateral fourth port 37 at the extension 36 from an outlet chamber 45 between the second end wall 22 and the valve piston 42 , where the outlet chamber 45 facing surface of the valve piston 42 is conical, so that it attaches to a paragraph within the extension 26 comes to the plant. Because the fourth connection 37 with the braking distance simulator 15 connected in this way is the simulator valve 17 educated. This connects or closes the connection of the inlet chamber designed as an annular chamber 44 with the outlet chamber 45 , Furthermore, it is located inside the valve piston 42 in a transverse bore to the inlet chamber 44 closing check valve 46 , via which a connection between the inlet chamber 44 and the outlet chamber 45 can be produced and that the function of in the 1 shown check valve 18 takes over.

Furthermore, the stepped piston has a plunger 47 passing through the second port 24 passes and to the valve piston 42 can be applied.

The execution after 4 Figure 11 shows the valve in movement from a home position to a switch position: the first port 23 is being opened to connect to the pump 13 to make the second connection 24 is still open. But you realize that the plunger 47 on the valve piston 42 interacts with the simulator valve 17 to open.

When the shift is complete, the second port is 24 closed and the valve piston 42 moved so far that that simulator valve 17 is open and thus a connection of the fourth port 37 , which communicates with the brake travel simulator, to the third port 41 that with the master cylinder 1 connected is made.

The check valve 18 in the transverse bore emptying the pedal travel simulator is used after completion of braking.

The execution after 5 corresponds to the execution of the 3 with the difference that the two pumps 13 for the two brake circuits are operated by one motor and not by a common motor.

The 6 shows an embodiment of the Bremsanalage, which is essentially the execution of the 2 equivalent.

However, the two switching valves 14 of the same type and correspond to the design of the switching valve to 3 , However, the area ratios and the return spring are designed so that an intermediate position can be set, in which for a certain pressure range, the branches to both the master cylinder and the pump 13 are open. The valves are thus used as 4/3-way valves.

LIST OF REFERENCE NUMBERS

1

Master Cylinder

2

pedal piston

3

floating piston

4

pedal chamber

5

floating chamber

6

wheel brake

7

wheel brake

8th

intake valve

9

intake valve

10

outlet valve

11

outlet valve

12

reservoir

13

pump

14

switching valve

15

braking distance simulator

16

simulator line

17

simulator valve

18

check valve

19

Simulator spring package

20

hollow cylinder

21

bulkhead

22

bulkhead

23

connection

24

connection

25

stepped piston

26

inlet chamber

27

inlet chamber

28

valve spring

29

Difference face

30

room

31

outlet

32

outlet

33

check valve

34

switching valve

35

connection

36

renewal

37

connection

40

front

41

connection

42

plunger

43

longitudinal bore

44

inlet chamber

45

outlet

46

check valve

47

tappet

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10213216314 A1 [0002]

Claims (9)

Vehicle brake system with a pedal-operated master cylinder (1), an external pressure transducer and a Bremswegsimulator (15), and wheel brakes (6, 7), of which at least one via a branching brake line, in their common section, a normally closed electromagnetically actuated outlet valve (10, 11) is arranged, both with the master cylinder (1) and with the external pressure transducer is connectable and via a pressure-relief line, which has a normally closed electromagnetically actuated outlet valve (10, 11), with a pressure medium sink is connectable, and with a switching valve (14) in the branch point of the brake pipe, the master cylinder (1), the external pressure transducer or both with the at least one wheel brake (6, 7) connects depending on its switching position, and with a simulator valve (17), the master cylinder (1) with the Bremswegsimulator (15) connects, characterized in that each switching valve (14, 34 ) is an exclusively hydraulically actuated valve, wherein the control of the switching valve (14, 34) by the differential pressure between the master cylinder (1) and the brake pressure transducer takes place. Vehicle brake system after Claim 1 , characterized in that each switching valve (14, 34) and the simulator valve (17) are exclusively hydraulically actuated valves. Vehicle brake system after Claim 1 , characterized in that the switching valves (14, 34) are either designed so that either only the master cylinder (1) or the external pressure transducer to the wheel brakes (6, 7) is connected, or designed so that they can additionally occupy a central position in which both the master cylinder (1) and the external pressure transducer to the wheel brakes (6, 7) are connected. Vehicle brake system after Claim 1 , characterized in that the switching valve (14, 34) has a stepped piston (25) whose two end faces (21, 22) are loaded by the pressure of the master cylinder (1) or by the pressure of the external pressure transducer. Vehicle brake system after Claim 4 , characterized in that in the switching valve (14, 34), a further valve piston (42) is provided which is mechanically actuated by a stepped piston. Vehicle brake system after Claim 1 , characterized in that the brake system is a dual-circuit brake system with wheel brakes in each brake circuit, wherein at least one brake circuit via a branching brake line, in the common portion of a normally closed electromagnetically actuated inlet valve (8, 9) is arranged, both with the master cylinder ( 1) as well as with the external pressure transducer and via a pressure relief line, which has a normally closed electromagnetically actuated outlet valve (10, 11), with a Druckmittelsenke connectable, and with a respective switching valve (14, 34) in the branch point of the brake line of the respective Braking circuit, depending on its switching position, the master cylinder (1), the external pressure or both with the least one wheel brake (6, 7) connects, and with a simulator valve (17) connecting the pedal pressure chamber with the Bremswegsimulator (15). Vehicle brake system after Claim 6 , characterized in that the master brake cylinder (1) is a tandem master cylinder having a pedal piston (2) and a floating piston (3), the brake travel simulator (15) being connected to the pedal pressure chamber located between the pedal piston (2) and the floating piston (3) (4) of the tandem master cylinder. Vehicle brake system after Claim 7 , characterized in that the simulator valve (17) is integrated in the switching valve (14, 34) of the brake circuit, which is connected to the pedal pressure chamber (4). Vehicle brake system after Claim 4 , characterized in that the switching valve (14, 34) each having four terminals (23, 24, 37, 41), two switching positions and a middle position, wherein the wheel brake (6, 7) both with the master cylinder (1) and is connected to the external pressure transducer.

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