Vehicle brake system with anti-skid apparatus

• US 5,131,729 A
• Filed: 10/31/1990
• Issued: 07/21/1992
• Est. Priority Date: 12/07/1989
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Wetzel, Gerhard
• Primary Examiner(s): Graham, Matthew C.
• Assistant Examiner(s): Poon, Peter M.
• Application Number:
  US07/606,267
• Time in Patent Office: 629 Days
• Field of Search: 303/111, 303/113 AP, 303/115 R, 303/115 PP, 303/116 R, 303/842
• US Class Current: 303/113.5
• CPC Class Codes: B60T 8/17616 Microprocessor-based systems
• CPC Class Codes: B60T 8/346 2 Channel systems B60T8/345 takes precedence
• CPC Class Codes: B60T 8/4275 Pump-back systems
• CPC Class Codes: B60T 8/94 on a fluid pressure regulator
• CPC Class Codes: Y10S 303/901 ABS check valve detail

Abstract

A known vehicle brake system having four wheel brakes, belonging to two brake circuits, for four wheels has an anti-skid apparatus with two electrically controllable brake pressure modulators, two wheel rotation sensors, and two brake pressure adaptors. The wheel rotation sensors are assigned to one front wheel and one diagonally opposed rear wheel, and each controls one brake pressure modulator, which belongs to the same wheel as the wheel rotation sensor. The brake pressure of a wheel brake located on the same axle on the opposite side of the vehicle is also controlled by a brake pressure modulator via a brake pressure adaptor. If only one wheel rotation sensor is provided per axle, only the wheel associated directly with the wheel rotation sensor can be braked optimally. The other wheel on the same axle may be overbraked or underbraked. This interferes with controllability of the vehicle and/or may have the disadvantage of overly long stopping distances. In the novel vehicle brake system, each of the two wheel rotation sensors is assigned to a separate front wheel and controls one brake pressure modulator for its respective front wheel. The two rear wheel brakes are each coupled via a brake pressure adaptor to the brake pressure modulator on the same side. A pressure reduction for the right front wheel that is effected in anti-skid operation results in a pressure reduction in the same direction for the right rear wheel.

Claims

1. A vehicle brake system having a dual-circuit brake pressure source, two brake circuits (12, 13) and wheel brakes (7-10) associated with them for front and rear wheels, and an anti-skid apparatus (11), the anti-skid apparatus having two brake pressure modulators (16, 17) and two brake pressure adaptors (30, 31), each brake pressure adaptor (30, 31) has a cylinder (34) and piston (35) displaceable in said cylinder, said piston is acted upon by a pressure from an associated brake pressure modulator (16, 17) for control purposes, a check valve (37) is provided between the piston (35) and an associated connection (12, 13) of the master brake cylinder (3) with said cylinder (34), said check valve has a stationary valve seat (38), a movable closing element (39) and a valve closing spring (40) that acts on the valve closing element (39), the valve closing spring (40) is weaker than the restoring spring (36) and said check valve (37) is opened in a direction of the master brake cylinder in the event of a pressure excess of an associated rear wheel brake relative to the master brake cylinder (3), each brake pressure modulator being controllable as a function of a rotation behavior of an associated wheel, the wheels being distributed on two sides of the vehicle, and each brake pressure adaptor being hydraulically controllable by one of the brake pressure modulators at a time to adapt the brake pressure of a wheel brake connected to it to the brake pressure of the wheel brake that is directly connected to the brake pressure modulator, each brake pressure modulator is controllable as a function of a rotational behavior of one associated front wheel and is connected to that wheel brake, and a brake pressure adaptor connected to the respective brake pressure modulator is connected to a wheel brake of a rear wheel on the same side of the vehicle.

2. A vehicle brake system as defined by claim 1, which includes a safety device (32, 33) which forms a bypass associated with an associated brake pressure adaptor (30, 31), by means of said safety device the rear wheel brake (10, 9) is supplied with pressure from the brake pressure source (3).

3. A vehicle brake system as defined by claim 2, in which an electrically operating wheel rotation sensor (19, 21) is associated with each front wheel;

an electric control unit (18) is connected to both wheel rotation sensors (19,

     21) for acting electrically upon the brake pressure modulators (16,

     17) as a function of the wheel rotation behavior of the respectively associated wheel rotation sensor (19,

     21); and

that a sensor (23) that observes a transverse motion behavior of the rear wheels is associated with the control unit (18), the signals of said sensor (23) are observed by the control unit (18) so that when threshold values are exceeded it controls at least one of the brake pressure modulators (16,

     17).

4. A vehicle brake system as defined by claim 3, in which said sensor (23) is embodied as a transverse acceleration sensor and is disposed in a region located between the center of gravity and one end of the vehicle.

5. A vehicle brake system as defined by claim 3, in which said sensor (23) is embodied as a yawing motion sensor.

6. A vehicle brake system as defined by claim 4, in which said sensor (23) is embodied as a yawing motion sensor.

7. A vehicle brake system as defined by claim 2, in which each safety device (32, 33) includes a 2/2-way valve (51, 52) and a closing device, which has a cylinder (46), with a control connection (48) connected to the brake pressure source (3), and a piston (50) that by means of this control connection (48) is subjected to the pressure of the brake pressure source (3).

8. A vehicle brake system as defined by claim 7, in which an electrically operating wheel rotation sensor (19, 21) is associated with each front wheel;

an electric control unit (18) is connected to both wheel rotation sensors (19,

     21) for acting electrically upon the brake pressure modulators (16,

     17) as a function of the wheel rotation behavior of the respectively associated wheel rotation sensor (19,

     21); and

that a sensor (23) that observes a transverse motion behavior of the rear wheels is associated with the control unit (18), the signals of said sensor (23) are observed by the control unit (18) so that when threshold values are exceeded it controls at least one of the brake pressure modulators (16,

     17).

9. A vehicle brake system as defined by claim 8, in which said sensor (23) is embodied as a transverse acceleration sensor and is disposed in a region located between the center of gravity and one end of the vehicle.

10. A vehicle brake system as defined by claim 8, in which said sensor (23) is embodied as a yawing motion sensor.

11. A vehicle brake system as defined by claim 9, in which said sensor (23) is embodied as a yawing motion sensor.

12. A vehicle brake system as defined by claim 7, in which in a region of the control connection (48), a valve closing spring (49) embodied as a compression spring is disposed in the cylinder (46);

that opposite this valve closing spring (49), a closing body (51) of the 2/2-way valve is coupled to the piston (50);

that a valve seat (52) associated with the valve closing body (51) is disposed on an end (53) of the cylinder (46) opposite the control connection (48);

said valve seat (52) communicates permanently with the brake pressure source (3); and

at least one connection (55) disposed in the region of the valve seat (52) is connected to the rear wheel brake (10) and the associated brake pressure adaptor (30,

     31).

13. A vehicle brake system as defined by claim 12, in which an electrically operating wheel rotation sensor (19, 21) is associated with each front wheel;

an electric control unit (18) is connected to both wheel rotation sensors (19,

     21) for acting electrically upon the brake pressure modulators (16,

     17) as a function of the wheel rotation behavior of the respectively associated wheel rotation sensor (19,

     21); and

that a sensor (23) that observes a transverse motion behavior of the rear wheels is associated with the control unit (18), the signals of said sensor (23) are observed by the control unit (18) so that when threshold values are exceeded it controls at least one of the brake pressure modulators (16,

     17).

14. A vehicle brake system as defined by claim 13, in which said sensor (23) is embodied as a transverse acceleration sensor and is disposed in a region located between the center of gravity and one end of the vehicle.

15. A vehicle brake system as defined by claim 13, in which said sensor (23) is embodied as a yawing motion sensor.

16. A vehicle brake system as defined by claim 14, in which said sensor (23) is embodied as a yawing motion sensor.

17. A vehicle brake system as defined by claim 1, in which an electrically operating wheel rotation sensor (19, 21) is associated with each front wheel;

an electric control unit (18) is connected to both wheel rotation sensors (19,

     21) for acting electrically upon the brake pressure modulators (16,

     17) as a function of the wheel rotation behavior of the respectively associated wheel rotation sensor (19,

     21); and

that a sensor (23) that observes a transverse motion behavior of the rear wheels is associated with the control unit (18), the signals of said sensor (23) are observed by the control unit (18) so that when threshold values are exceeded it controls at least one of the brake pressure modulators (16,

     17).

18. A vehicle brake system as defined by claim 17, in which said sensor (23) is embodied as a transverse acceleration sensor and is disposed in a region located between the center of gravity and one end of the vehicle.

19. A vehicle brake system as defined by claim 17, in which said sensor (23) is embodied as a yawing motion sensor.

20. A vehicle brake system as defined by claim 18, in which said sensor (23) is embodied as a yawing motion sensor.