GB2140112A - Controlling front/rear brake force distribution in dual-circuit brake system for motor vehicles - Google Patents
Controlling front/rear brake force distribution in dual-circuit brake system for motor vehicles Download PDFInfo
- Publication number
- GB2140112A GB2140112A GB08412605A GB8412605A GB2140112A GB 2140112 A GB2140112 A GB 2140112A GB 08412605 A GB08412605 A GB 08412605A GB 8412605 A GB8412605 A GB 8412605A GB 2140112 A GB2140112 A GB 2140112A
- Authority
- GB
- United Kingdom
- Prior art keywords
- pressure
- brake
- input
- wheel brake
- actual value
- 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.)
- Granted
Links
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
- B60T8/26—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force characterised by producing differential braking between front and rear wheels
- B60T8/266—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force characterised by producing differential braking between front and rear wheels using valves or actuators with external control means
- B60T8/268—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force characterised by producing differential braking between front and rear wheels using valves or actuators with external control means using the valves of an ABS, ASR or ESP system
-
- 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
- B60T8/17—Using electrical or electronic regulation means to control braking
- B60T8/176—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS
- B60T8/1766—Proportioning of brake forces according to vehicle axle loads, e.g. front to rear of vehicle
Landscapes
- Engineering & Computer Science (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Regulating Braking Force (AREA)
- Hydraulic Control Valves For Brake Systems (AREA)
Abstract
Variable brake force adjustment for the front and rear axles is achieved by using the solenoid valves (15, 16, 17) provided in an anti-skid system. For this purpose, actual value sensors (22, 23) for the brake pressure are disposed between the solenoid valves (15, 16) and the front wheel brake cylinders (10, 11) and their output signals are fed to a respective four- pole network (27, 28) having a transmission function. An actual value sensor (24) for the control pressure is disposed between the master brake cylinder (19) and the solenoid valve (17) for controlling braking of the rear wheels. The output signal of the actual value sensor (24) for the control pressure and the output signals of the four- pole networks (27, 28) are fed respectively to two comparators (25, 26) which control the solenoid valves (15, 16) for the wheel brake cylinders (10, 11) of the front wheels in dependence on the difference between the signals. <IMAGE>
Description
SPECIFICATION
Dual-circuit brake system for vehicles
The invention relates to a dual-circuit brake system for vehicles, having an anti-skid system.
In vehicle brake systems, utilization of the brake force of the rear axle brakes is improved by using so-called brake force regulators which, in dependence upon pressure, deceleration or load, control the brake pressure for the rear axle as a function of the brake pressure at the front axle or at the front wheels. Simple, inexpensive constructions of these brake force regulators are relatively inaccurate and, although the expensive versions in the case of dual-circuit brake systems incorporating anti-skid systems are very accurate, they are relatively complicated and require critical adjustment.
The present invention resides in a dualcircuit brake system for a motor vehicle, having a master brake cylinder, wheel brake cylinders respectively associated with each wheel and an anti-skid system, the anti-skid system comprising solenoid valves each associated with a respective wheel brake cylinder and/or brake circuit and each having three switching positions, an electronic control means for actuating the solenoid valves, actual value sensors for the front wheel brake pressures disposed respectively between each front wheel brake cylinder and the associated solenoid valve, an actual value sensor for the control pressure disposed between the master brake cylinder and a solenoid valve which is incorporated in a brake circuit which acts upon at least one rear wheel brake cylinder, respective comparators for controlling the solenoid valves associated with the front wheel cylinders, the first input of each comparator being supplied with the output signal of the actual value sensor for the control pressure, and respective multi-pole networks whose output signals are supplied to the second inputs of the comparators and whose input value is the output signal of the respective associated actual value sensor for the front wheel brake pressure, each multi-pole network having a transmission function which corresponds to a predetermined characteristic of the front wheel brake pressure in dependence upon the control pressure, and each comparator supplying a pressure-reducing signal to the associated solenoid valve when the input signal at the first input is smaller than that at the second input, and supplying a pressure-holding signal when the input signal at the first input is equal to or greater than that at the second input.
This has the advantage that variable brake force adjustment at the front and rear axles is achieved without additional brake force regulators by means of the solenoid valves of the anti-skid system which are in any case provided. This brake force adjustment enables better utilization of the rear axle brake in the range of partial braking on the one hand and, on the other hand, more uniform wear on the front and rear axle brakes is obtained. There is no need for any adjustments such as are required in, for example, load-dependent brake force regulators. The dual-circuit brake system in accordance with the invention can be made inexpensively and with low weight and does not require any additional installation and assembly costs.The dual-circuit brake circuit can be of adaptive design, so that fluctuations of the coefficient of friction (or road adhesion) can be reduced by utilizing the control signals from the anti-skid system.
The invention will be further described hereinafter, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a block circuit diagram of a dual-circuit brake system for a motor vehicle,
Figure 2 is a block circuit diagram of a modified dual-circuit brake system of Fig. 1, in which the brake circuits are split up diagonally, and
Figure 3 is a graph of the transmission characteristic of a four-pole network of the circuit of Fig. 1.
The dual-circuit brake system illustrated in
Fig. 1 has a brake circuit i for the front wheels and a brake circuit II for the rear wheels. Each wheel has an associated wheel brake cylinder 10, 11, 12, 1 3. The dualcircuit brake system also has an anti-skid system 1 4 which includes three solenoid valves 15, 16, 1 7 and electronic control means 1 8 for controlling the solenoid valves 15, 16, 1 7. An anti-skid system of this kind is known, and so requires no further description.Of the three solenoid valves 15, 16, 17, the solenoid valve 1 5 is associated with the wheel brake cylinder 10 for the left hand front wheel, the solenoid valve 1 6 is associated with the wheel brake cylinder 11 for the right hand front wheel, and the solenoid valve 1 7 is associated with the two wheel brake cylinders for the rear wheels for common control of the rear axle. In the known manner, the solenoid valves 15, 16, 1 7 have three switching positions: free passage, pressure-holding and pressure reduction. In the brake circuit I, the two solenoid valves 15, 1 6 are connected in parallel and to a corresponding outlet of a master brake cylinder 1 9 having a brake force booster 20.The brake circuit Il having the solenoid valve 1 7 is connected to the other outlet of the master brake cylinder 1 9. The master brake cylinder 1 9 is actuated by a brake pedal 21.
A respective actual value sensor 22 or 23 for the brake pressure of the front wheels is disposed between each front wheel brake cylinder 10 or 11 and the associated solenoid valve 1 5 or 16. An actual value sensor 24 for the control pressure is disposed in the brake circuit II between the master brake cylinder 1 9 and the solenoid valve 1 7 which is associated with the two wheels brake cylinders 12, 1 3 for the rear wheels. The output of the actual value sensor 24 for the control pressure is connected to an input of a first comparator 25 and to an input of a second comparator 26. The other input of the comparator 25 is connected to the output of a first four-pole network 27, and the second input of the second comparator 26 is connected to the output of a second four-pole network 28.The actual value sensor 22 for the front wheel brake pressure is connected to the input of the first four-pole network 27, and the actual value sensor 23 for the front wheel brake pressure is connected to the input of the second four-pole network 28. The four-pole networks 27, 28 are of identical construction and have a transmission function which corresponds to a predetermined characteristic of the front wheel brake pressure P in dependence upon the control pressure Pc of the master brake cylinder 1 9. Such a characteristic of the front wheel brake pressure in dependence upon the control pressure is shown in Fig. 3. The solid curve of the brake pressure shown in Fig. 3 corresponds to the transmission function of the four-pole networks 27, 28. This transmission function may be varied in dependence upon input parameters.Parameters of this kind are the control pressure, the load on the rear axle, slip of the rear axle relative to the reference speed of the front axle, or a control signal produced for the rear axle by the electronic control means 1 8.
Variations of the transmission function of the four-pole networks 27, 28 obtainable by such parameters are represented in Fig. 3 by broken lines. The input of the parameters into the four-pole networks 27, 28 is shown symbolically in Fig. 1 by arrows at the right-hand side thereof.
Each of the comparators 25, 26 controls a respective solenoid valve 1 5 or 1 6 by means of which the wheel brake cylinders 10, 11 of the front wheels are controlled. Control is effected such that the comparator 25 or 26 supplies a signal to the associated solenoid valve 1 5 or 1 6 for reducing the pressure in the wheel brake cylinder 10 or 11 respectively when the input signal at the first input connected to the actual value sensor 24 for the control pressure is smaller than that at the second input of the comparator 25 or 26 connected to the four-pole network 27 or 28 respectively, and supplies a signal for pressure-holding when the input signal at the first input is equal to or greater than that at the second input.
The characteristic of the brake pressure at the rear axle in dependence upon the control pressure is shown chain-dotted in the graph of
Fig. 3. As may be seen, the brake pressure is approximately linearly dependent upon the control pressure. The brake pressure of the front wheel cylinders is always reduced relative to the brake pressure at the rear axle by the transmission function of the four-pole networks 27, 28, since, as will readily be seen in
Fig. 3, the front wheel brake pressure is always lower than the rear wheel brake pressure at optional control pressures Pc.
When a control pressure P'c is produced in the brake circuits I and Il by, for example, the master brake cylinder 19, this control pressure, which is detected in the brake circuit II by the actual value sensor 24 for the control pressure, is applied as an eiectric input value to one input of each of the two comparators 25, 26. As may be seen in Fig. 3, such a control pressure would result in a rear axle brake pressure P'. If it is assumed that such a brake pressure P' is in the first instance also produced at the two wheel brake cylinders 10, 11 of the front wheels, this brake pressure P' is detected by the actual value sensors 22 and 23 for the front wheel brake pressure and is applied to the four-pole networks 27 and 28 as an electrical input value.By virtue of the transmission function, the outputs of the four-pole networks 27 and 28 respectively carry an output value which corresponds to the control pressure value Pc (Fig. 3). This output value of the four-pole networks 27, 28 is present at the second input of each of the two comparators 25 and 26 and is greater than that electrical output value of the actual value sensor 24 for the control pressure which is present at the other input and which corresponds to the control pressure P'. In accordance with what has been said above, the comparator 25 or the comparator 26 supplies a pressure-reducing signal to the excitation winding of the solenoid valve 1 5 or 1 6 which is thereby switched to its switching position "pressure reduction".The brake pressure in the respective wheel brake cylinder 10 or 11 is reduced until the electrical input values at the comparators 25 and 26 are equal. The comparator 25 or 26 then supplies a pressure-holding signal to the respective associated solenoid valve 1 5 or 16, whereby the solenoid valve 1 5 or 1 6 is switched to its second switching position "pressure holding".
The dual-circuit brake system of Fig. 2 differs from that of Fig. 1 only in that the brake circuits are split up diagonally. The wheel brake cylinders 10 and 1 3 for the left hand front wheel and the right hand rear wheel respectively are actuated by the brake circuit 1, and the wheel brake cylinders 11 and 1 2 for the right hand front wheel and the left hand rear wheel respectively are actuated by the brake circuit 11. A solenoid valve 1 5, 16, 17, 29 is associated with each of the wheel brake cylinders 10, 11, 12, 13. Correspondingly, the anti-skid system 14' is of four-channel construction and not of three channel construction as shown in Fig. 1, and the electronic control means 18' has four control channels. As in the circuit arrangement of Fig. 1, the actual value sensors 22 and 23 for the front wheel brake pressure are again disposed between the solenoid valves 1 5 and 16 on the one hand and the wheel brake cylinders 10, 11 of the front wheels on the other hand. The actual value sensor 24 for the control pressure is disposed in one of the brake circuits I or II between the master brake cylinder 1 9 and the respective solenoid valve 16 or 15.
Referring to Fig. 2, the actual value sensor 24 for the control pressure is disposed in the brake circuit II. In the same manner, the comparators 25 and 26 and the four-pole networks 27 and 28 are again provided and are indicated symbolically by the block 30 in
Fig. 2. The electrical connection of the actual value sensors 22, 23, 24 to the block 30 is identical to that shown in Fig. 1.
Claims (6)
1. A dual-circuit brake system for a motor vehicle, having a master brake cylinder, wheel brake cylinders respectively associated with each wheel and an anti-skid system, the antiskid system comprising solenoid valves each associated with a respective wheel brake cylinder and/or brake circuit and each having three switching positions, an electronic control means for actuating the solenoid valves, actual value sensors for the front wheel brake pressures disposed respectively between each front wheel brake cylinder and the associated solenoid valve, an actual value sensor for the control pressure disposed between the master brake cylinder and a solenoid valve which is incorporated in a brake circuit which acts upon at least one rear wheel brake cylinder, respective comparators for controlling the solenoid valves associated with the front wheel cylinders, the first input of each comparator being supplied with the output signal of the actual value sensor for the control pressure, and respective multi-pole networks whose output signals are supplied to the second inputs of the comparators and whose input value is the output signal of the respective associated actual value sensor for the front wheel brake pressure, each multi-pole network having a transmission function which corresponds to a predetermined characteristic of the front wheel brake pressure in dependence upon the control pressure, and each comparator supplying a pressure-reducing signal to the associated solenoid valve when the input signal at the first input is smaller than that at the second input, and supplying a pressure-holding signal when the input signal at the first input is equal to or greater than that at the second input.
2. A system as claimed in claim 1, in which the transmission functions of the multipole networks are set such that the front wheel brake pressure is always lower than the rear wheel brake pressure at an optional control pressure.
3. A system as claimed in claim 1 or 2, in which the transmission function is variable in dependence upon input parameters applied to the multi-pole networks.
4. A system as claimed in claim 1, 2 or 3, in which the multi-pole networks are four-pole networks.
5. A system as claimed in claims 3 and 4, in which the input parameters are control pressure, load on the rear axle, slip of the rear axle relative to the reference speed of the front axle, and a control signal, supplied by the electronic regulating means for the rear axle.
6. A dual-circuit brake systemm for a motor vehicle, constructed and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19833318020 DE3318020A1 (en) | 1983-05-18 | 1983-05-18 | TWO-CIRCUIT BRAKE SYSTEM FOR VEHICLES |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8412605D0 GB8412605D0 (en) | 1984-06-20 |
| GB2140112A true GB2140112A (en) | 1984-11-21 |
| GB2140112B GB2140112B (en) | 1986-12-10 |
Family
ID=6199248
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08412605A Expired GB2140112B (en) | 1983-05-18 | 1984-05-17 | Controlling front/rear brake force distribution in dual-circuit brake system for motor vehicles |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS59216758A (en) |
| DE (1) | DE3318020A1 (en) |
| FR (1) | FR2546118B1 (en) |
| GB (1) | GB2140112B (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0189077A2 (en) * | 1985-01-23 | 1986-07-30 | WABCO Vermögensverwaltungs-GmbH | Brake pressure regulating device |
| EP0442089A2 (en) * | 1990-02-13 | 1991-08-21 | Robert Bosch Gmbh | Brake system |
| GB2241294A (en) * | 1990-02-07 | 1991-08-28 | Daimler Benz Ag | A hydraulic brake system for a road vehicle |
| FR2687969A1 (en) * | 1992-02-28 | 1993-09-03 | Bosch Gmbh Robert | COMPRESSED AIR BRAKE SYSTEM FOR MOTOR VEHICLES. |
| US5383720A (en) * | 1992-12-17 | 1995-01-24 | Robert Bosch Gmbh | Braking system for motor vehicles |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3643141A1 (en) * | 1986-12-17 | 1988-07-07 | Teves Gmbh Alfred | BRAKE SYSTEM FOR MOTOR VEHICLES |
| DE4142670A1 (en) * | 1991-12-21 | 1993-06-24 | Wabco Westinghouse Fahrzeug | METHOD FOR BRAKING A VEHICLE |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1376581A (en) * | 1972-03-30 | 1974-12-04 | Teldix Gmbh | Anti-lock control system for vehicle brakes |
| GB1530607A (en) * | 1974-12-20 | 1978-11-01 | Wabco Westinghouse Gmbh | Anti-skid braking system |
| GB1581594A (en) * | 1976-05-21 | 1980-12-17 | Wabco Fahrzeugbremsen Gmbh | Apparatus for regulating the braking force of a vehicle |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS595462B2 (en) * | 1977-09-27 | 1984-02-04 | 日本国有鉄道 | Front and rear wheel braking force distribution device for vehicles |
| IT1143485B (en) * | 1981-04-03 | 1986-10-22 | Ettore Cordiano | BRAKING SYSTEM FOR VEHICLES WITH BRAKE DISTRIBUTOR CONTROLLED BY ELECTRONIC PROCESSOR |
| DE3124755A1 (en) * | 1981-06-24 | 1983-01-13 | Robert Bosch Gmbh, 7000 Stuttgart | VEHICLE BRAKE SYSTEM |
-
1983
- 1983-05-18 DE DE19833318020 patent/DE3318020A1/en not_active Withdrawn
-
1984
- 1984-05-14 JP JP9478384A patent/JPS59216758A/en active Pending
- 1984-05-17 GB GB08412605A patent/GB2140112B/en not_active Expired
- 1984-05-18 FR FR8407797A patent/FR2546118B1/en not_active Expired
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1376581A (en) * | 1972-03-30 | 1974-12-04 | Teldix Gmbh | Anti-lock control system for vehicle brakes |
| GB1530607A (en) * | 1974-12-20 | 1978-11-01 | Wabco Westinghouse Gmbh | Anti-skid braking system |
| GB1581594A (en) * | 1976-05-21 | 1980-12-17 | Wabco Fahrzeugbremsen Gmbh | Apparatus for regulating the braking force of a vehicle |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0189077A2 (en) * | 1985-01-23 | 1986-07-30 | WABCO Vermögensverwaltungs-GmbH | Brake pressure regulating device |
| EP0189077A3 (en) * | 1985-01-23 | 1987-06-24 | Wabco Westinghouse Fahrzeugbremsen Gmbh | Brake pressure.regulating device |
| GB2241294A (en) * | 1990-02-07 | 1991-08-28 | Daimler Benz Ag | A hydraulic brake system for a road vehicle |
| US5125724A (en) * | 1990-02-07 | 1992-06-30 | Mercedes-Benz Ag | Road vehicle hydraulic brake system with electronic braking force distribution control |
| GB2241294B (en) * | 1990-02-07 | 1994-01-05 | Daimler Benz Ag | A hydraulic brake system for a road vehicle |
| EP0442089A2 (en) * | 1990-02-13 | 1991-08-21 | Robert Bosch Gmbh | Brake system |
| EP0442089A3 (en) * | 1990-02-13 | 1992-05-06 | Robert Bosch Gmbh | Brake system |
| FR2687969A1 (en) * | 1992-02-28 | 1993-09-03 | Bosch Gmbh Robert | COMPRESSED AIR BRAKE SYSTEM FOR MOTOR VEHICLES. |
| US5383720A (en) * | 1992-12-17 | 1995-01-24 | Robert Bosch Gmbh | Braking system for motor vehicles |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2546118A1 (en) | 1984-11-23 |
| FR2546118B1 (en) | 1988-04-15 |
| GB2140112B (en) | 1986-12-10 |
| JPS59216758A (en) | 1984-12-06 |
| DE3318020A1 (en) | 1984-11-22 |
| GB8412605D0 (en) | 1984-06-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19930517 |