GB2257215A - Hydraulic braking systems - Google Patents

Hydraulic braking systems Download PDF

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Publication number
GB2257215A
GB2257215A GB9213636A GB9213636A GB2257215A GB 2257215 A GB2257215 A GB 2257215A GB 9213636 A GB9213636 A GB 9213636A GB 9213636 A GB9213636 A GB 9213636A GB 2257215 A GB2257215 A GB 2257215A
Authority
GB
United Kingdom
Prior art keywords
brake
valve
shut
pressure
line
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9213636A
Other versions
GB9213636D0 (en
Inventor
Helmut Peuschel
Guenther Schmidt
Wolfgang Bernhardt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of GB9213636D0 publication Critical patent/GB9213636D0/en
Publication of GB2257215A publication Critical patent/GB2257215A/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
    • B60T8/50—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition having means for controlling the rate at which pressure is reapplied to or released from the brake
    • B60T8/5018—Pressure reapplication using restrictions
    • B60T8/5025—Pressure reapplication using restrictions in hydraulic brake systems
    • B60T8/5037—Pressure reapplication using restrictions in hydraulic brake systems closed systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
    • B60T8/42—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition having expanding chambers for controlling pressure, i.e. closed systems
    • B60T8/4275—Pump-back systems
    • B60T8/4291—Pump-back systems having means to reduce or eliminate pedal kick-back
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
    • B60T8/48—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition connecting the brake actuator to an alternative or additional source of fluid pressure, e.g. traction control systems
    • B60T8/4809—Traction control, stability control, using both the wheel brakes and other automatic braking systems
    • B60T8/4827—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems
    • B60T8/4863—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems closed systems
    • B60T8/4872—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems closed systems pump-back systems

Description

2237215
-1DESCRIPTION HYDRAULIC BRAKING SYSTEMS
This invention relates to a hydraulic braking system having an anti-skid control device, particularly for motor vehicles.
A hydraulic braking system is known from German Patent Application P 40 34 113.5, in which the shutoff valve in the brake line between the master brake cylinder and the connection of the high-pressure pump is switched to its shut-off position if, during driveslip control operation which is possible in addition to anti-skid control operation, brake pressure is to be built up, by means of the pump, in the wheel brake of the vehicle wheel subject to an inadmissibly large amount of drive slip. The non- return valve located in the by-pass line connected in parallel with the shutoff valve has a flow-through direction from the master brake cylinder to the wheel brake and allows the driver to perform a braking operation during driveslip control. Problems can ensue in the bralking system if the shut-off valve jams and remains in its shut-off position, since the return of pressure medium from the wheel brake is obstructed.
The shut-off valve assumes its flow-through position during anti-skid control, so that, on the one hand, pressure medium extracted during the pressure- -2reduction phase from the wheel brake of the vehicle wheel subject to the risk of locking can be returned to the master brake cylinder and, on the other hand, pressure medium can be displaced from the master brake cylinder to the wheel brake during the pressure-buildup phase. Since the valve arrangement, associated with the wheel brake, for -brake pressure modulation performs a rapid succession of switching operations with a high acceleration and retardation of the pressure medium in the brake line, particularly in the pressure-build-up phase, an intensive development of noise and brake pedal vibration occurs, particularly during anti-skid control, and therefore reduces the comfort of the braking system or of the vehicle.
In accordance with the present invention a hydraulic braking system is provided having an antiskid control device, a brake line extending between a Dedal-operated master brake cylinder and at least one wheel brake, which has a valve arrangement for brake pressure modulation, switching phases of pressurebuild-up, pressure-holding and pressure- reduction at the wheel brake, a high-pressure pump for feeding pressure medium into the brake line between the master brake cylinder and the valve arrangement, a shut-off valve which is disposed in the brake line between the -3master brake cylinder and the connection of the highpressure pump to the brake line and which is switchable into its shut-off position by a control device, wherein the shut-off valve is by-passed by a by-pass line in which a throttle is located, and the shut-off valve assumes its shut- off position during anti-skid control.
This has the advantage that the pressure medium has to overcome the throttle during the pressurebuild-up-phase of anti-skid control, whereby the rate of flow of the pressure medium is reduced and consequently the rate of the increase in pressure is reduced during switching of the valve arrangement. This results in a considerable reduction in the intensity of switching noise during the pressurebuild-up phase during anti-skid control. Furthermore, the driver is less aware of the reaction of the pressure medium, delivered from the master brake cylinder, on the brake pedal. Thus, there is an overall increase in the comfort of the braking system.
Preferably, the braking system has a second bypass line which by-passes the shut-off valve and in which a non-return valve is disposed, which closes in the direction from the master-brake cylinder to the wheel brake.
This ensures that, during the pressure-reduction 1 -4phase, the pressure medium can flow off to the master brake cylinder by way of the non-return valve, bypassing the shut-off valve. Thus, a potential fault in the shut-off valve has less effect on the functioning of the braking system, since rapid debraking and return of pressure medium to the master brake cylinder is always ensured.
By way of example only, the present invention will now be described, with reference to the accompanying drawing which is a circuit diagram of a hydraulic multi-circuit braking system for motor vehicles constructed in accordance with the present invention.
A hydraulic multi-circuit braking system 1 for motor vehicles, as shown in the drawing, is equipped with an anti-skid control device 2. The braking system 1 has a pedal-operated master brake cylinder 3 with a pressure medium reservoir 4 mounted thereon. A brake line 5 of a first brake circuit I associated with the front axle of the vehicle leads from the master brake cylinder 3. The brake line 5 branches into two brake lines 6 and 7. The brake line 6 leads to a wheel brake 8 of, for example, the left front wheel (not illustrated). The brake line 7 is connected to a wheel brake 9 of, for example, the right front wheel (also not illustrated).
A brake line 10 of a second brake circuit II, with which the wheel brakes 11 and 12 of the rear axle of the vehicle are associated, also leads from the master brake cylinder 3. The brake circuit II is not shown in detail, since it is unnecessary for the description of the invention.
A shut-off valve 15 in the form of a two-port, two-position valve is disposed in the brake line 5 of the brake circuit 1. The shut-off valve 15 has a spring-operated flow-through position 15a and an electromagnetically switchable shut-off position 15b. The shut-off valve 15 is by-passed by a first by-pass line 16 incorporating a throttle 17. Furthermore, a second by-pass line 18 by-passing the shut-off valve 15 is provided and incorporates a spring-loaded nonreturn valve 19. The non- return valve 19 is shut-off in the direction from the master brake cylinder 3 to the wheel brakes 8, 9.
A first valve arrangement 22 for brake pressure modulation is associated with the wheel brake 8. The valve arrangement 22 comprises an inlet valve 23 and an outlet valve 24. The two valves 23 and 24 are in the form of two-port, two-position valves. The inlet valve 23 disposed in the brake line 6 has a springoperated flow-through position 23a and an electromagnetically switchable shut-off position 23b. The inlet valve 23 is by-passed by a third by-pass line which incorporates a non-return valve 26 which shuts in the direction from the master brake cylinder 3 to the wheel brake 8. The outlet valve 24 of the valve arrangement 22 is located in a return line 27 which leads from the brake line 6 between the inlet valve 23 and the wheel brake 8. The outlet valve 23 has a spring-operated shut-off position 24 and an electromagnetically switchable flow-through position 24b.
In the same way, a valve arrangement 32 for brake pressure modulation is associated with the wheel brake 9 and comprises an inlet valve 29 in the brake line 7 and an outlet valve 30 in a return line 31.
The valve arrangement 22 is (in the same way as the valve arrangement 32) switchable into switching positions for pressure build-up, pressureholding, and pressure-reduction in the wheel brake 8. When in the switching position for the build-up of pressure, the inlet valve 23 assumes its flow-through position 23a and the outlet valve 24 assumes its shut-off position 24a, as is shown in the drawing. When in the pressureholding position, the inlet valve 23, like the outlet valve 24, is switched to its shut-off position 23b. When in the pressure-reduction position, the inlet valve 23 assumes its shut-off 1 -7position 23b, and the outlet valve 24 is switched to its flow-through position 24b.
The return line 27 serving for the return of pressure medium extracted from the wheel brakes 8, 9 terminates at a suction connection 35 of a highpressure pump 37 drivable by an electric drive motor 36. An accumulator chamber 38 for intermediate storage of pressure medium is also connected to the return line 27. A feed line 40 leads from a pressure connection 39 of the high-pressure pump 37 and opens into the brake line 6 between the shut-off valve 15 and the valve arrangement 22. Viewed in the direction of flow, a damping chamber 41 and a throttle 42 with a pressure-limiting valve 43 connected in parallel thereto are located in the feed line 40.
The braking system 1 also has an electronic control device 46 which monitors the rotary behaviour of the vehicle wheels (not illustrated) by rotational speed sensors 47, 48, 49, 50 and, in accordance with a predetermined control algorithm, switches the valves 15, 23, 24, 29, 30 and the drive motor 36 of the highpressure pump 37 during anti-skid control.
The functioning of the braking system 1 is as follows:
Upon braking initiated by the driver of the vehicle, the shut-off valve 15 and the valves 23, 24, -829, 30 of the valve arrangements 22, 32 assume the illustrated positions. Brake pressure is generated in the wheel brakes 8, 9, 11, 12 by actuation of the master brake cylinder 3 by displacing quantities of pressure medium in the brake lines 5, 6, 7 of the brake circuit I and in the brake lines 10, 11, 12 of the brake circuit II. The.control device 46 monitors the rotary behaviour of the vehicle wheels on the basis of the signals of the rotational speed sensors 47, 48, 49, 50.
If, for example, the vehicle wheel associated with the wheel brake 8 locks, the control device 46 switches the shut-off valve 15 in the brake line 5 into its shut-off position 15b, and the valve arrangement 22 in the brake line 6 into its switching iDosition for the reduction of Dressure. Pressure medium can then flow from the wheel brake 8 into the accumulator chamber 38 by way of the return line 27, so that the brake pressure in the wheel brake 8 is reduced. The high-pressure pump 37, is at the same time switched on by the control device 46, and delivers the pressure medium extracted from the wheel brake 8 into the brake line 6 by way of the feed line 40. The damping chamber 41, in conjunction with the throttle 42, dampens the pulsations caused by the high-pressure pump 37, so that the component quantity p -9of pressure medium delivered to the master brake cylinder 3 by way of the second by-pass line 18 and overcoming the non-return valve 19, and by way of the brake line 5, causes only a slight reaction on the pedal.
Pressure-holding and pressure-reduction phases switched by means of the valve arrangement 22 can follow such a phase for the reduction of brake pressure. The control dev-Lce 46 switches phases for the build-up of brake pressure upon the stabilisation of the rotational behaviour of the vehicle wheel associated with the wheel brake 8. Since the shut-off valve 15 in the brake line 5 continues to assume its shut-off position 15b, component quantities of pressure medium flow from the actuated master brake cylinder 3 into the wheel brake 8 by way of the first by-pass line 16 having the throttle 17, and the brake line 6. The throttle 17 thereby reduces the rate of increase of brake Dressure in the wheel brake 8. The repeated switching of the inlet valve 23 taking place during the phases for the build-up of brake pressure therefore causes only a slight development of noise and a reduced pedal reaction at the master brake cylinder 3.
Upon conclusion of anti-skid control operation, the control device 46 switches the shut-off valve 15
1 _10into its flow-through position 15a and the valve arrangement 22 into the illustrated positions of the inlet valve 23 and of the outlet valve 24. The drive motor 36 of the high-pressure pump 37 is also switched off.
Advantageously, the arrangement of the shut-off valve 15, the throttle 17 and the non-return valve 19 is disposed, as already described, in the brake circuit associated with the front axle of a vehicle. This is after all where relatively large component quantities of pressure medium have to be displaced between the master brake cylinder 3 and the wheel brake 8, 9 during anti-skid control operation. Alternatively, however, the abovementioned arrangement may also be used in the rear axle brake circuit. Moreover, it may also be used in a so-called K-sDlit of the brake circuits, that is, in braking systems in which the wheel brakes of diagonally opposite vehicle wheels are associated with each brake circuit. The arrangement of shut-off valve, throttle and non-return valve may also be associated with all the brakes of the respective brake circuit or with only the front axle brakes or the rear axle brakes. The braking system may also have a drive-slip control device as in German Patent Application P 40 34 113.5.

Claims (3)

_11CLAIMS
1. A hydraulic braking system is provided having an anti-skid control device, a brake line extending between a pedal-operated master brake cylinder and at least one wheel brake, which has a valve arrangement for brake pressure modulation, switching phases of pressure-build-up, pressureholding and pressure-reduction at the wheel brake, a highpressure pump for feeding pressure medium into -'-he brake line between the master brake cylinder and the valve arrangement, a shut-off valve which is disposed in the brake line between the master brake cylinder and the connection of the high-pressure pump to the brake line and which is switchable into its shut-off position by a control device, wherein the shut-off valve is by-passed by a by-pass line in which a throttle is located, and the shut-off valve assumes its shut-off position during antiskid control.
2. A hydraulic braking system as claimed in claim 1, further having a second by-pass line which by-passes the shut-off valve and in which a nonreturn valve is disposed which closes in the direction from the masterbrake cylinder to the wheel brake.
3. A hydraulic braking system substantially as herein described, with reference to and as illustrated in the accompanying drawing.
GB9213636A 1991-06-29 1992-06-26 Hydraulic braking systems Withdrawn GB2257215A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19914121603 DE4121603A1 (en) 1991-06-29 1991-06-29 HYDRAULIC BRAKE SYSTEM WITH ANTI-BLOCK PROTECTION CONTROL DEVICE, ESPECIALLY FOR MOTOR VEHICLES

Publications (2)

Publication Number Publication Date
GB9213636D0 GB9213636D0 (en) 1992-08-12
GB2257215A true GB2257215A (en) 1993-01-06

Family

ID=6435081

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9213636A Withdrawn GB2257215A (en) 1991-06-29 1992-06-26 Hydraulic braking systems

Country Status (3)

Country Link
JP (1) JPH05185914A (en)
DE (1) DE4121603A1 (en)
GB (1) GB2257215A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994027848A1 (en) * 1993-05-28 1994-12-08 Itt Automotive Europe Gmbh Brake system for motor vehicles with a device for adjusting both the brake and drive slip

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4220835A1 (en) * 1992-06-25 1994-01-05 Teves Gmbh Alfred Antiskid hydraulic brake control with reduced valve noise - has recirculating pump driving through flow restriction switched by pressure control valve
DE4319227A1 (en) * 1993-06-09 1994-12-15 Teves Gmbh Alfred Hydraulic brake system with slip control

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2163503A (en) * 1984-08-09 1986-02-26 Nippon Denso Co Hydraulic pressure control device for use in vehicle anti-skid braking system
GB2213222A (en) * 1987-12-29 1989-08-09 Nippon Abs Ltd Brake fluid pressure control apparatus in vehicle skid control systems
GB2214250A (en) * 1987-12-24 1989-08-31 Teves Gmbh Alfred Anti-skid-controlled hydraulic brake system
DE3912322A1 (en) * 1987-10-17 1990-10-18 Teves Gmbh Alfred Antilocking hydraulic brake circuit - links wheel cylinders to master brake cylinder by flow restriction and parallel solenoid valve

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2163503A (en) * 1984-08-09 1986-02-26 Nippon Denso Co Hydraulic pressure control device for use in vehicle anti-skid braking system
DE3912322A1 (en) * 1987-10-17 1990-10-18 Teves Gmbh Alfred Antilocking hydraulic brake circuit - links wheel cylinders to master brake cylinder by flow restriction and parallel solenoid valve
GB2214250A (en) * 1987-12-24 1989-08-31 Teves Gmbh Alfred Anti-skid-controlled hydraulic brake system
GB2213222A (en) * 1987-12-29 1989-08-09 Nippon Abs Ltd Brake fluid pressure control apparatus in vehicle skid control systems

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994027848A1 (en) * 1993-05-28 1994-12-08 Itt Automotive Europe Gmbh Brake system for motor vehicles with a device for adjusting both the brake and drive slip

Also Published As

Publication number Publication date
GB9213636D0 (en) 1992-08-12
JPH05185914A (en) 1993-07-27
DE4121603A1 (en) 1993-01-07

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)