GB2091829A - Improvements in hydraulic anti-skid braking systems for vehicles - Google Patents
Improvements in hydraulic anti-skid braking systems for vehicles Download PDFInfo
- Publication number
- GB2091829A GB2091829A GB8200947A GB8200947A GB2091829A GB 2091829 A GB2091829 A GB 2091829A GB 8200947 A GB8200947 A GB 8200947A GB 8200947 A GB8200947 A GB 8200947A GB 2091829 A GB2091829 A GB 2091829A
- Authority
- GB
- United Kingdom
- Prior art keywords
- brake
- actuators
- actuator
- front wheel
- skid
- 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
- B60T8/32—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
- B60T8/343—Systems characterised by their lay-out
- B60T8/344—Hydraulic systems
- B60T8/345—Hydraulic systems having more than one brake circuit per wheel
-
- 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
- B60T8/1761—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS responsive to wheel or brake dynamics, e.g. wheel slip, wheel acceleration or rate of change of brake fluid pressure
- B60T8/17613—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS responsive to wheel or brake dynamics, e.g. wheel slip, wheel acceleration or rate of change of brake fluid pressure based on analogue circuits or digital circuits comprised of discrete electronic elements
Abstract
An anti-skid braking system for a four wheel vehicle having brakes on the front wheels (1, 2) and rear wheels (3, 4) is disclosed. Each front wheel brake is adapted to be applied by at least two actuators (5, 6; 7, 8) of similar size, and each rear wheel brake is adapted to be applied by at least one actuator (9, 10). The system comprises first and second brake-applying circuits. The first circuit comprises a first source (12) of brake- applying fluid, and a first connection between the first source (12) and one actuator (5, 7) for each front wheel brake (1, 2) and the actuator (10) for one of the rear wheel brakes, and the second circuit comprises a second source (13) of brake-applying fluid, and a second connection between the second source (13) and the other actuator (6, 8) for each front wheel brake (1, 2) and the actuator (9) of the other of the rear wheel brakes. First and second modulators (16, 15) are provided for modulating the supply of fluid from the first and second sources (12, 13) only to the respective actuators (7, 6) of different front wheel brakes (1, 2), and third and fourth modulators (14, 17) are provided for modulating the supply of fluid from the first and second sources (12, 13) to the remaining respective actuators (5, 8) of the front wheel brakes and to the actuators (10, 9) of the diagonally opposite rear wheel brakes (4, 3). Two skid sensors (18, 19) are each adapted to provide a skid signal dependent upon the behaviour of the respective one of the front wheels (1, 2), and a control module (19) is adapted to operate one or more of the four modulators (14, 15, 16, 17) in accordance with the nature and magnitude of the skid signal or signals. <IMAGE>
Description
SPECIFICATION
Improvements in hydraulic anti-skid braking systems for vehicles
This invention relates to hydraulic anti-skid braking systems for vehicles of the kind in which a supply of hydraulic fluid under pressure, for example from an hydraulic master cylinder, is adapted to be supplied to an actuator of a wheel brake through a modulator which is adapted to modulate the pressure applied to the actuator in accordance with a skid signal from skid sensing means.
In known anti-skid braking systems of the kind set forth, for four wheel vehicles, it is customary to provide a modulator for each actuator of each front wheel brake, and a single modulator for a pair of actuators, each adapted to actuate a brake on a different rear wheel of a vehicle, in combination with four sensors, each for producing a skid signal for each wheel. When the braking system is of a dual brake-applying circuit type with the circuits operated from different pressure sources, suitably different pressure spaces of dual or tandem hydraulic master cylinders, the front wheel brakes are provided with two actuators, and each rear wheel brake is provided with at least one actuator.In such a layout corresponding actuators on the brakes on opposite front wheels are connected in pairs, and each pair is connected to a different one of the two sources and to an actuator of one of the rear wheel brakes. When each rear wheel brake is operated by a single actuator, upon failure of one of the sources, both front wheel brakes can still be operated by the two actuators which are still operative together with one of the rear wheel brakes. This is known as an 'L' or parallel split. When each rear wheel brake is operated by two actuators, corresponding actuators on opposite sides of the vehicles are connected to an interconnected pair on the front wheels. In such a layout both front wheel brakes and both rear wheel brakes can all still be applied upon failure of one of the sources. This is known as an 'H' split.
It will be appreciated that, in such systems, to provide a modulator for modulating the braking pressure to each actuator will require six modulators in the case of an 'L' split, and eight modulators in the case of an 'H' split, with a suitably complex control module.
According to our invention in an anti-skid braking system for a four wheel vehicle having brakes on the front and rear wheels, each front wheel brake is adapted to be applied by at least two actuators of similar size, and each rear wheel brake is adapted to be applied by at least one actuator, the system comprising first and second brake-applying circuits, the first circuit comprising a first source of brakeapplying fluid, and a first connection between the first source and one actuator for each front wheel brake and the actuator for one of the rear wheel brakes, and the second circuit comprising a second source of brake-applying fluid, and a second connection between the second source and the other actuator for each front wheel brake and the actuator of the other of the rear wheel brakes, first and second modulators for modulating the supply of fluid from the first and second sources only to the respective actuators of different front wheel brakes, third and fourth modulators for modulating the supply of fluid from the first and second sources to the remaining respective actuators of the front wheel brakes and to the actuators of the diagonally opposite rear wheel brakes, two skid sensors, each for providing a skid signal dependent upon the behaviour of a respective one of the front wheels, and a control module for operating one or more of the four modulators in accordance with the nature and magnitude of the skid signal or signals.
With this system therefore we are able to provide differential relief of the braking effort applied to the wheels in accordance with the nature and direction of a skid signal. For example, we can arrange for a low level skid signal from the sensor associated with one front wheel to actuate the modulator which is operative to relieve the pressure applied to one of the actuators of the brake of that wheel only, or for it to actuate the modulator which is operative to relive the pressure applied both to one of the actuators of that wheel and the actuator of the diagonally opposite rear wheel brake which is common to that brake circuit.Again a skid signal of greater magnitude can be utilised to actuate the other modulator of the pair associated with the said one front wheel, or, in the case of a skid signal of large magnitude, both the modulators of that pair, whereby to relieve the pressure applied to both actuators of the front wheel brake, and the actuator of the said diagonally opposite rear wheel brake.
Which modulator is actuated in response to a low level skid signal will depend upon the characteristics of the particular braking system with which our invention is to be utilised. For example, in a braking system in which the relative sizes of the actuators of the front and rear wheel brakes are chosen to ensure that skidding of a front wheel must occur before skidding of a rear wheel can take place we prefer to relieve the pressure applied to one of the front wheel brake actuators only, effectively to reduce substantially by one half the effort applied to that wheel.
However, when the system is of the type incorporating an apportioning valve of the kind adapted to vary the braking effort between the front wheel brakes and the rear wheel brakes in accordance with the loading on the vehicle, or any transfer of weight during braking, we prefer to relieve the pressure applied to the front wheel brake actuators and to a rear brake actuator when a low level signal is produced.
One embodiment of our invention is illustrated in the accompanying drawings in which:
Figure lisa layout of an 'L' split hydraulic anti-skid braking system for a vehicle;
Figure 2 is a layout of an electronic control circuit for the braking system to Figure 1;
Figure 3 is a graph showing the relationship between braking pressure applied to brakes on front and rearwheelsfora system having an apportioning valve; and
Figure 4 is a graph similar to Figure 3 but for a system not provided with an apportioning valve.
The braking system shown in the layout of Figure 1 comprises two separate hydraulic brake-applying circuits, each of 'L' split configuration, for a vehicle having two front wheels 1, 2 and two rear wheels 3, 4. As illustrated a brake on the wheel 1 is adapted to be applied by two hydraulic actuators 5, 6, and a brake on the wheel 2 by two hydraulic actuators 7, 8.
All the actuators 5, 6,7 and 8 are of substantially the same size. A brake on the wheel 3 is adapted to be applied by a single actuator 9, and that on the wheel 4 by a single actuator 10.
A pedal-operated master cylinder 11 has two pressure spaces 12, 13. The pressure space 12 is connected through pipe-lines to the actuators 5, 7, and 10 to define one of the brake-applying circuits, and the pressure space 13 is connected through pipe-lines to the actuators 6,8 and 9 to define the other brake-applying circuit.
Afirst modulator 14 is located between the pressure space 12 and the actuatorS, with the actuator 10 connected to the pipe-line between the modulator 14 and the actuatorS. A second modulator 15 is located between the pressure space 13 and the actuator 6. Athird modulator 16 is located between the pressure space 12 and the actuator 7.
Finally a fourth modulator 17 is located between the pressure space 13 and the actuator 8, with the actuator 9 connected to the pipe-line between the modulator 17 and the actuator 8.
In the electronic control circuit of Figure 2 a sensor 18 responsive to the behaviour of the front wheel 1 is adapted to emit a skid signal which is supplied to a control module 19, and a sensor 20 responsive to the behaviour of the other front wheel 2 is adapted to emit a skid signal which is also applied to the control module 19.
Depending upon which sensor 18 or 20 emits a skid signal, and the magnitude of such a signal, the control module 19 is arranged to operate one or more ofthefour modulators 14to 17 in orderto relieve the. pressure from the master cylinder 11 applied to the respective actuators.
Assuming, for example, that the sensor 18 emits a low skid signal indicative of a low skid of the wheel 1, then such a signal is only sufficient to cause the control module 19to operate eitherthe modulator 14 or the modulator 15to:
A. reduce by one half the braking effort on the wheel 1, since the actuators 5, and 6 are of substantially equal size, and the whole of the braking effort on the diagonally opposite wheel 4; or
B. reduce by one half the braking effort on the wheel 1 only with the brakes on both rear wheels 3 and 4 still being fully applied.
Where the characteristics of braking systems are as shown in Figure 4 of the drawings where we arrange for the front wheels to skid before the rear wheels are able to skid, condition B above is preferred. However, where the characteristics are as shown in Figure 3 of the drawings with the braking system incorporating an apportioning valve, condition A above is preferred to ensure relief of pressure applied to a rear wheel which might not necessariy skid only after a front wheel has skidded.
Should the sensor 18 emit a greater skid signal, indicative of a higher skid of the wheel 1, then the other modulator 15 or 14will be operated.
Finally, when the sensor 18 emits a large skid signal, indicative of a severe skid, then both modulators 14 and 15 will be operated to relievethe pressure applied to all three actuators 5, 6 and 10 thereby relieving the braking effort on the front wheel 1 and the diagonally opposite rear wheel 4.
This has the advantage that any tendency for the vehicle to spin due to possible skidding of the unsensed wheel 3 is restricted by the wheel 4 since more lateral load can be applied to that wheel 4 due to the increased grip which can be imparted to it as the braking effort on it has been relieved.
In the embodiment described above we are able to control six effectively independent braking means by the use offour modulators and to caterfortwo levels of minor skids on wheels by the use of only two sensors.
Where a brake comprises a disc brake of the opposed "pot" fixed caliper type, it is to be understood that the term actuator used herein is intended to refer to a pair of hydraulic pistons which works in opposed cylinders in opposite limbs of the caliper. In such a construction at least the disc brakes on the front wheels will be of the four "pot" type, that is to say they will each be provided with two pairs of pistons.
Claims (8)
1. An anti-skid braking system for a four wheel vehicle having brakes on the front and rear wheels, in which each front wheel brake is adapted to be applied by at least two actuators of similar size, and each rear wheel brake is adapted to be applied by at least one actuator, the system comprising first and second brake-applying circuits, the first circuit comprising a first source of brake-applying fluid, and a first connection between the first source and one actuator for each front wheel brake and the actuator for one of the rear wheel brakes, and the second circuit comprising a second source of brake-applying fluid, and a second connection between the second source and the other actuator for each front wheel brake and the actuator of the other of the rear wheel brakes, first and second modulators for modulating the supply of fluid from the first and second sources only to the respective actuators of different front wheel brakes, third and fourth modulators for modulating the supply of fluid from the first and second sources to the remaining respective actuators of the front wheel brakes and to the actuators of the diagonally opposite rear wheel brakes, two skid sensors, each for providing a skid signal dependent upon the behaviour of a respective one of the front wheels, and a control module for operating one or more of the four modulators in accordance with the nature and magnitude of the skid signal or signals.
2. A system as claimed in Claim 1, in which a low level skid signal from the sensor associated with one front wheel is adapted to actuate the modulator which is operative to relieve the pressure applied to one of the actuators of the brake of that wheel only.
3. A system as claimed in Claim 1, in which a low level system from the sensor associated with one front wheel is adpated to actuate the modulator which is operative to relief the pressure applied both to one of the actuators of that wheel and the actuator of the diagonally opposite rear wheel brake which common to that brake circuit.
4. A system as claimed in Claim 1, in which a skid signal of greater magnitude is adapted to be utilised to actuate the other modulator of the pair associated with the said one front wheel.
5. A system as claimed in Claim 1, in which a skid signal of large magnitude is adapted to actuate both the modulators of the pair on the said one front wheel, whereby to relieve the pressure applied to both actuators of that front wheel brake, and the actuator of the said diagonally opposite rear wheel brake.
6. A system as claimed in any preceding claim in which the relevant sizes of the actuators of the front and rear wheel brakes are chosen to ensure that skidding of a front wheel must occur before skidding of a rear wheel can take place, whereby a low level skid signal is operative to relieve the pressure applied to one of the front wheel brake actuators only, effectively to reduce substantially by one half the effort applied to that wheel.
7. A system as claimed in any of Claims 1 to 5, incorporating an apportioning valve of the kind adapted to vary the braking effort between the front wheel brakes and the rear wheel brakes in accordance with the loading on the vehicle, or any transfer of weight during braking, in which a low level signal is adapted to relieve the pressure applied to the actuators of a front wheel brake and to the actuator of the diagonally opposite rear wheel brake.
8. An anti-skid braking system for a vehicle substantially as described herein with reference to and as illustrated in the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8200947A GB2091829B (en) | 1981-01-23 | 1982-01-13 | Improvements in hydraulic anti-skid braking systems for vehicles |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8102123 | 1981-01-23 | ||
| GB8200947A GB2091829B (en) | 1981-01-23 | 1982-01-13 | Improvements in hydraulic anti-skid braking systems for vehicles |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2091829A true GB2091829A (en) | 1982-08-04 |
| GB2091829B GB2091829B (en) | 1985-02-06 |
Family
ID=26278205
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8200947A Expired GB2091829B (en) | 1981-01-23 | 1982-01-13 | Improvements in hydraulic anti-skid braking systems for vehicles |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2091829B (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2519919A1 (en) * | 1982-01-15 | 1983-07-22 | Daimler Benz Ag | BRAKE FORCE CONTROL DEVICE FOR AT LEAST ONE AXLE OF A VEHICLE EQUIPPED WITH AN ANTI-BLOCKING SYSTEM |
| GB2156461A (en) * | 1984-03-30 | 1985-10-09 | Teves Gmbh Alfred | Brake system for automotive vehicles with controllable brake force distribution |
| EP0203778A2 (en) | 1985-05-28 | 1986-12-03 | LUCAS INDUSTRIES public limited company | Improvements in hydraulic braking systems for vehicles |
| US4962971A (en) * | 1987-11-19 | 1990-10-16 | Akebono Brake Industry Co., Ltd. | Anti-skid control system for motor vehicles |
| EP0481227A1 (en) * | 1990-10-16 | 1992-04-22 | MAN Nutzfahrzeuge Aktiengesellschaft | Double circuit brake system for vehicles |
| EP3018020A3 (en) * | 2014-08-20 | 2016-06-29 | KNORR-BREMSE Systeme für Nutzfahrzeuge GmbH | Hybrid brake system for a vehicle, and method for triggering a hybrid brake system for a vehicle |
-
1982
- 1982-01-13 GB GB8200947A patent/GB2091829B/en not_active Expired
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2519919A1 (en) * | 1982-01-15 | 1983-07-22 | Daimler Benz Ag | BRAKE FORCE CONTROL DEVICE FOR AT LEAST ONE AXLE OF A VEHICLE EQUIPPED WITH AN ANTI-BLOCKING SYSTEM |
| GB2156461A (en) * | 1984-03-30 | 1985-10-09 | Teves Gmbh Alfred | Brake system for automotive vehicles with controllable brake force distribution |
| EP0203778A2 (en) | 1985-05-28 | 1986-12-03 | LUCAS INDUSTRIES public limited company | Improvements in hydraulic braking systems for vehicles |
| EP0203778A3 (en) * | 1985-05-28 | 1987-01-28 | Lucas Industries Public Limited Company | Improvements in hydraulic braking systems for vehicles |
| US4962971A (en) * | 1987-11-19 | 1990-10-16 | Akebono Brake Industry Co., Ltd. | Anti-skid control system for motor vehicles |
| EP0481227A1 (en) * | 1990-10-16 | 1992-04-22 | MAN Nutzfahrzeuge Aktiengesellschaft | Double circuit brake system for vehicles |
| EP3018020A3 (en) * | 2014-08-20 | 2016-06-29 | KNORR-BREMSE Systeme für Nutzfahrzeuge GmbH | Hybrid brake system for a vehicle, and method for triggering a hybrid brake system for a vehicle |
| EP3018020B1 (en) | 2014-08-20 | 2017-10-11 | KNORR-BREMSE Systeme für Nutzfahrzeuge GmbH | Hybrid brake system for a vehicle, and method for triggering a hybrid brake system for a vehicle |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2091829B (en) | 1985-02-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |