DE19905660A1 - Electronically regulated brake actuating system for motor vehicles has pressure source with proportional regulating valve that enables pressure produced by pump to be adjusted - Google Patents

Abstract

The system has a main brake cylinder (2) with a pressure source (30) with at least one pump (31) controlled by a control unit to apply pressure to wheel brakes that can be connected to the main cylinder via at least one hydraulic connection that can be closed by isolating valves (12). There are a device for detecting a driver deceleration demand and wheel brake inlet and outlet valves. The pressure source has a proportional regulating valve (32) that enables the pressure produced by the pump to be adjusted.

Description

The invention relates to an electronically controllable Brake actuation system for motor vehicles, with a Master brake cylinder, with at least one pump having pressure source by a control unit is controllable and with the pressure of the wheel brakes Motor vehicle can be acted upon by at least a hydraulic valve that can be shut off using isolating valves Connection to the master cylinder are connectable with a device for recognizing the Driver deceleration request and with one of the wheel brakes upstream inlet valve and outlet valve.

In DE-OS 196 36 432 such is Vehicle brake system described. To control the of a pump generated pressure in the wheel brakes are Inlet and outlet valves in the known Vehicle brake system identical as pressure limiting and Differential pressure solenoid valves designed. The use of this However, valve type leads to high production costs. In addition there is a high thermal load during operation electronic control unit since the valves also during a normal braking numerous switching operations subject to. The pump must also have a higher one Have maximum power than it does for the real one Operation is necessary because during braking Loss of fluid due to leakage at the valves can occur due to the system. Furthermore, due to  the constant possibility of pollution of the brake system the risk of jamming of the valves and thus can lead to a non-reproducible braking behavior.

The invention is therefore based on the object Vehicle brake system of the type mentioned above to further develop that the disadvantages mentioned above avoided become. In particular, the brake system should be such be trained that on the pressure relief and Differential pressure solenoid valves can be dispensed with.

This object is achieved in that the Pressure source has a control valve that has a setting of the pressure generated by the pump. Thereby there is no control or regulation of the pump and it can use simple and inexpensive pump types become.

In a particularly inexpensive embodiment of the Invention, the pump is a constant current pump.

The control valve is preferably a proportional valve and thereby allows a variable setting of the desired Pressure. Such a regulation of the pressure can the use of analog valves as intake and exhaust valves the wheel brakes are dispensed with. Instead, you can known, e.g. B. valves used in ABS systems become. By using these valves in the brake system result in lower production costs and a lower development risk. Because during one Normal braking no switching of these valves is necessary there is also a lower thermal load on the Investment. In an ABS standard case, the control quality  increased because the valves known from ABS systems are very short Have switching times. By contrast to Proportional valves will have minimal leakage losses in addition to the oversizing, which is no longer necessary the pump a further improvement in the control behavior reached. After all, they excel in ABS systems valves used by a very low Contamination risk, which creates a low risk jamming and thus failure or malfunction the braking system is given.

The proportional valve is advantageously a Seat valve, which is connected in parallel with the pump. The inlet of the seat valve with the suction side is Pump and the output connected to the pressure side. Seat valves are characterized by their simple construction and high reliability.

The seat valve can be actuated by an electromagnet be the force applied by the electromagnet changeable depending on the driver deceleration request is. This measure can be taken by the driver Setpoint given to the electronically controllable braking system become.

In an advantageous development of the The inventive concept of the valve body of the seat valve an extension on that with that through the pump generated pressure can be applied. This is it to take a constructive measure to reduce that Actuating force to be applied to electromagnets, whereby the electromagnet can be made smaller can.  

In an alternative embodiment, this can Proportional valve be a spool valve that with the Pump connected in series. By using a Gate valve is a very precise dosage of the pressure possible and there is an improvement in Control behavior.

The slide valve can be operated by an electromagnet be operable, the slide position depending can be changed by the driver deceleration request and thus a setpoint determined by the driver Control system is passed.

In a preferred embodiment, a hydraulic Connection may be provided through which one from the print force resulting in the wheel brakes against the the electromagnet applied force to the slide can be exercised. This measure results in a Regulation of the pressure in a hydraulic pressure control circuit and it can be used for other electronic components Regulation of the pressure can be dispensed with.

Alternatively, a pressure sensor for sensing the Pressure is provided in the wheel brakes, wherein in Dependence of the value determined by the pressure sensor force exerted by the electromagnet on the slide is changed. The slide valve can in such Embodiment can be designed pressure-balanced so that due to the electrical regulation of disturbances such as Friction, tolerances and flow forces are very good Control behavior is achieved. In addition, the electromagnet small size for actuating the slide valve become. Additional valve functions, such as B. a de-energized  closed (SG) valve that connects between a pressure medium reservoir and one Liquid storage can separate into this Embodiment of the slide valve are integrated, which makes the brake system even more compact can.

A significant reduction in noise is common to everyone Embodiments achieved in that the pump Gear pump is.

In a preferred construction, a device for Filling the wheel brakes provided. This will in Low-pressure range the dynamics and especially that Responsiveness of the brake system according to the invention increased.

The device for prefilling the Wheel brakes as at least one low pressure linear pump be trained. This takes place very quickly active pressure build-up.

Alternatively, the wheel brakes can be primed at least one low-pressure accumulator can be provided. The Low pressure accumulator creates an easy to manufacture Component.

The invention is described in the description below Reference to the accompanying drawing explained.

The drawing shows:

Fig. 1 shows an embodiment of an electronic brake system of the invention,

Fig. 2 is a pressure source as shown in FIG. 1, which is provided with two linear pumps to the incidents of the brake system,

Fig. 3 is a pressure source that is provided with a liquid reservoir to the incidents of the brake system,

Fig. 4 shows a pressure source with a linear valve connected in series with the pump.

The electronically controllable brake actuation system according to the invention shown in the drawing consists of a two-circuit master brake cylinder 2 which can be actuated by means of an actuation pedal 1 , preferably in the design of a tandem master cylinder which has pressure chambers 5 , 6 which are delimited and separated from one another by two pistons 3 , 4 are in connection with a pressureless pressure medium reservoir 7 .

The first pressure chamber 5 , to which a first pressure sensor 8 can be connected, is connected by means of a lockable first hydraulic line 9 , for example, to a first wheel brake 10 assigned to the front axle and to a second wheel brake 11 assigned to the rear axle, each of which has an electromagnetically actuated, preferably open (SO) inlet valve 13 , 14 upstream. The line 9 is shut off by means of a separating valve 12 . Via a further hydraulic line 20 , into which a 2/2-way valve 19 is inserted, the wheel brakes 10 , 11 are connected to the pressure side of a pressure source 30 having a control valve 32 and a pump 31 . A second pressure sensor 24 is also located in line 20 . In addition, the wheel brakes 10 , 11 are connected via a third hydraulic line 21 to the pressure medium reservoir 7 , into each of which an outlet valve 15 , 16 is inserted.

The second pressure chamber 6 of the master brake cylinder 2 can be connected on the one hand to the pressure source 30 and on the other hand to the other, not specified, pair of wheel brakes via a shut-off hydraulic line, which is likewise not designated by means of a second isolating valve. Since the structure of the hydraulic circuit connected to the second pressure chamber 6 of the master brake cylinder 2 corresponds identically to that in connection with the hydraulic circuit described above with the wheel brakes 10 , 11 , it need not be discussed in the text below.

The driven by an electric motor 23 , which can be controlled by a control unit 18 , pump 31 of the aforementioned pressure source 30 promotes a constant volume flow and z. B. to be preferred for reasons of noise minimization gear pump. The control valve 32 is a proportional valve and is designed as a seat valve 50 which can be actuated by an electromagnet 51 and which is open when the electromagnet 50 is de-energized. The valve body 52 of the seat valve 50 has an extension 53 , the end of which is connected to the pressure medium reservoir 7 in a space 54 . This measure reduces the magnetic force required to actuate the seat valve 50 , so that a compact design can be achieved. The seat valve 50 is connected in parallel to the pump 31 , so that its input is connected to the suction side of the pump 31 and its output is connected to the pressure side of the pump 31 .

The electronically controllable brake actuation system shown in FIG. 1 of the drawing functions as follows:
If a braking process is initiated by depressing the actuation pedal 1 , the actuation state is recognized by a device 22 for recognizing the driver's deceleration request and communicated to the electronic control unit 18 , the control signals of which cause the isolating valve 12 and the valve 19 to switch. The device 22 for recognizing the driver deceleration request can be formed, for example, by an actuation travel sensor 17 . The pressure sensor 8 sends a second message of the driver's deceleration request or a presetting of an actual pressure value to the electronic control unit 18 , which generates control signals for both the pressure source 30 and the control valve 32 . By energizing the electromagnet 51 of the control valve 32 , a corresponding magnetic force is generated, which presses the valve body 52 of the seat valve 50 against its valve seat 55 with a defined force. As a result, the connection between the pressure medium reservoir 7 and the pressure side of the pump 31 which is open when the seat valve 50 is deenergized is blocked. If the force acting on the valve body 52 , which is caused by the pressure generated by the pump 31 , exceeds the actuating force applied by the electromagnet 51 , the valve body 52 then releases the connection between the pressure side of the pump 31 and the pressure medium reservoir 7 . This provides the required proportionality between the driver's request and the pressure generated by the pressure source 30 . By opening the valve 19 which is arranged on the pressure side of the pressure source 30 and is preferably closed when de-energized, the wheel brakes 10 , 11 can be acted upon by the pressure generated by the pressure source 30 via the inlet valves 13 , 14 .

Figs. 2, 3, and 4 show alternative embodiments of the pressure source 30.

FIG. 2 shows the pressure source 30 according to FIG. 1, which is additionally provided with a device 40 for priming the wheel brakes 10 , 11 , -, - in order to improve the response behavior of the brake system. The device 40 comprises two low-pressure linear pumps 41 , 42 which are connected in parallel to the pump 31 . The pressure side of the low-pressure linear pumps 41 , 42 is connected to the line 21 leading to the wheel brakes, while the suction side thereof is connected to the pressure medium reservoir 7 . The low-pressure linear pumps 41 , 42 each have a piston 81 , which is guided in a housing 80 and can be moved by an electromagnet 82 . The piston 81 is supported on the inner wall of one end face of the housing 80 by a spring 83 . The space 84 thereby predetermined by the spring 83 can be filled with pressure medium, which can flow in from the pressure medium reservoir 7 via a first check valve 85 . In the end face of the housing 80 there is a second check valve 86 which is connected to the space 84 and which opens when the pressure medium volume is shifted towards the wheel brakes 10 , 11 , -, -. When actuated, the piston 81 is moved by the electromagnet 82 against the force generated by the spring 83 , the first check valve 85 is closed and the pressure medium in the space 84 can escape via the second check valve 86 . As a result, when the brake system is activated, the wheel brakes 10 , 11 , -, - are pre-filled until a pressure has been built up by the pump 31 . The low-pressure linear pumps 41 , 42 have a higher dynamic range in the low-pressure range than the pump 31, which is preferably designed as a high-pressure pump.

In Fig. 3, an alternative embodiment of the device 40 is shown for priming the brake system. It comprises a low-pressure accumulator 45 provided with a displacement sensor 46 for measuring the fill level, which is connected to the pressure side of the pump 31 via a preferably normally closed (SG) valve 47 , and a pressure-limiting valve 48 which is connected in parallel to the pump 31 . The displacement sensor 46 is connected to the electronic control unit 18 in order to supply information about the fill level of the low-pressure accumulator 45 to it. The low pressure accumulator 45 can e.g. B. be filled with pressure medium by the pump 31 . The pressure limiting valve 48 prevents accidental damage to all elements. If the brake system is activated, the valve 47 is opened and the wheel brakes 10 , 11 , -, - are pre-filled with the pressure medium stored in the low-pressure accumulator 45 .

In FIG. 4, an embodiment of the pressure source 30 is shown in which the control valve 32 formed as a slide valve 60 and is connected to the pump 31 in series. The structure of the pressure source 30 otherwise corresponds to the embodiment shown in FIG. 3. A slide 61 of the slide valve 60 is actuated by an electromagnet 62 , which is controlled by the electronic control unit 18 . The slide valve 60 has five connections 63 , 64 , 65 , 66 , 67 . The connection 64 connected to the pressure side of the pump 31 is not connected to any of the other connections 63 , 65 , 66 , 67 in the de-energized state of the electromagnet 62 , whereas the connection 66 connected to the wheel brakes 10 , 11 , - is connected to the one with the Pressure medium reservoir 7 connected port 65 is connected. In the energized state of the electromagnet 62 , the connection 65 has no connection to the other connections 63 , 64 , 66 , 67 , but the connection 64 is connected to the connection 66 . The connection 67 is connected to the connection 66 via a hydraulic line 71 . As a result, one end of the slide 61 can be subjected to the pressure of the wheel brakes. Pressure medium escaping from the slide 61 can flow back into the pressure medium reservoir 7 via the connection 63 . On the pressure side of the pump 32 there is a third pressure sensor 68 which is connected to the electronic control unit 18 .

The pressure control is carried out as follows: In the passive state, ie there is no braking request, the electromagnet 62 of the slide valve 60 is de-energized and the slide 61 separates the pump-side connection 64 from the connection 66 assigned to the wheel brakes 10 , 11 . In the event of a braking request, the electromagnet 62 is energized with a current corresponding to the braking request and predetermined by the control unit 18 , as a result of which the slide 61 is moved to the right against a spring 70 in the FIG. 4 shown. As a result, a connection between the connection 64 and the connection 66 is released, so that pressure can be built up in the wheel brakes 10 , 11 ,. The aforementioned connection between the connections 66 and 67 ensures that an additional force on the slide 61 acts in addition to the force exerted by the spring 70 against the force exerted by the electromagnet 62 . If this exceeds the force exerted by the electromagnet 62 , the slide 61 moves again to the left and the connection between the connections 64 and 66 is interrupted again. At the same time, a connection between the connections 66 and 65 is released, via which the pressure in the wheel brakes can be reduced. In this way, pressure control is provided by a hydraulic control circuit.

Alternatively, in a slightly modified embodiment, not shown, the pressure can also be controlled electronically with the slide valve 60 . For this purpose, instead of the previously mentioned connection 71 between the connections 66 and 67, a pressure sensor is used, the output signal of which is fed to the electronic control unit 18 , which changes the actuating force generated by the electromagnet 62 as a function of the measured value. By using an electronic control loop, disturbance variables such as. B. friction, tolerance, flow forces can be compensated in a simple manner. In this embodiment, the valve 47 can also be integrated into the slide valve 60 . The pressure in the brake system is set, as in the previously shown exemplary embodiments, by changing the actuating force applied by the electromagnet 62 .

That described electronically in the exemplary embodiments adjustable brake control system is not on its own  Brake system actuation desired by the driver limited, but also enables the implementation of known special functions such. B. Anti-slip control, electronic Driving stability program and brake assistant.  

Reference list

1

Operating pedal

2nd

Master brake cylinder

3rd

first piston

4th

second piston

5

first pressure room

6

second pressure room

7

Pressure fluid reservoir

8th

first pressure sensor

9

first line

10th

first wheel brake

11

second wheel brake

12th

Isolation valve

13

first inlet valve

14

second inlet valve

15

first exhaust valve

16

second exhaust valve

17th

Actuation travel sensor

18th

Control unit

19th

Pressure valve

20th

second line

21

third line

22

Facility

23

engine

24th

second pressure sensor

30th

Pressure source

31

pump

32

Control valve

40

Facility

41

first low pressure linear pump

42

second low pressure linear pump

45

Low pressure accumulator

46

Displacement sensor

47

Valve

48

Pressure relief valve

50

Seat valve

51

Electromagnet

52

Valve body

53

renewal

54

room

55

Valve seat

60

Slide valve

61

Slider

62

Electromagnet

63

first connection

64

second connection

65

third connection

66

fourth connection

67

fifth connection

68

third pressure sensor

69

fourth pressure sensor

70

feather

71

management

80

casing

81

piston

82

Electromagnet

83

feather

84

room

85

first check valve

86

second check valve

Claims (14)

1. Electronically controllable brake actuation system for motor vehicles, with a master brake cylinder ( 2 ), with a pressure source ( 30 ) having at least one pump ( 31 ) which can be controlled by a control unit ( 18 ) and with the pressure of which wheel brakes ( 10 , 11 ) of the motor vehicle can be acted upon, which can be connected to the master brake cylinder ( 2 ) via at least one hydraulic connection that can be shut off by means of separating valves ( 12 ), with a device for recognizing the driver's deceleration request ( 22 ), and with an inlet valve ( 13 ) upstream of the wheel brakes ( 10 , 11 ) , 14 ) and outlet valve ( 15 , 16 ), characterized in that the pressure source ( 30 ) has a control valve ( 32 ) which enables the pressure generated by the pump ( 31 ) to be adjusted. 2. Electronically controllable brake actuation system according to claim 1, characterized in that the pump ( 31 ) is a constant current pump. 3. Electronically controllable brake actuation system according to claim 1 or 2, characterized in that the control valve ( 32 ) is a proportional valve. 4. Electronically controllable brake actuation system according to claim 3, characterized in that the proportional valve is a seat valve ( 50 ) connected in parallel with the pump ( 31 ). 5. Electronically controllable brake actuation system as claimed in claim 4, characterized in that the seat valve (50) is operable by an electromagnet (51), wherein the force applied by the electromagnet (51) force is variable in dependence on the driver's request. 6. Electronically controllable brake actuation system according to claim 4 or 5, characterized in that the seat valve ( 50 ) has a valve body ( 52 ) which interacts with a valve seat ( 55 ) and can be acted upon by the pressure generated by the pump ( 31 ). 7. Electronically controllable brake actuation system according to one of claims 1 or 2, characterized in that the proportional valve is a slide valve ( 60 ) connected in series with the pump ( 31 ). 8. Electronically controllable brake actuation system according to claim 8, characterized in that the slide valve ( 60 ) can be actuated by an electromagnet ( 62 ), the position of a slide ( 61 ) being changeable as a function of the driver's request. 9. Electronically controllable brake actuation system according to claim 8, characterized in that a hydraulic connection ( 71 ) is provided, by which a force resulting from the pressure in the wheel brakes is exerted against the force exerted by the electromagnet ( 62 ) on the slide ( 61 ) can be. 10. Electronically controllable brake actuation system according to claim 8, characterized in that a pressure sensor is provided for sensing the pressure in the wheel brakes, the force exerted by the electromagnet ( 62 ) on the slide ( 61 ) depending on the value determined by the pressure sensor becomes. 11. Electronically controllable brake actuation system according to one of the preceding claims, characterized in that the pump ( 31 ) is a gear pump. 12. Electronically controllable brake actuation system according to one of the preceding claims, characterized in that a device ( 40 ) for pre-filling the wheel brakes ( 10 , 11 ) is provided. 13. Electronically controllable brake actuation system according to claim 12, characterized in that the device ( 40 ) for prefilling the wheel brakes ( 10 , 11 ) is designed as at least one low-pressure linear pump ( 41 , 42 ). 14. Electronically controllable brake actuation system according to claim 12, characterized in that the device ( 40 ) for prefilling the wheel brakes ( 10 , 11 ) is designed as at least one low-pressure accumulator ( 45 ).