Brake system for automotive vehicles with electric drive

• US 5,551,764 A
• Filed: 03/14/1995
• Issued: 09/03/1996
• Est. Priority Date: 11/24/1992
• Status: Expired due to Fees

• Current Assignee: ITT Automotive Europe GmbH
• Original Assignee: ITT Automotive Europe GmbH
• Inventors: Balz, Juergen, Kunze, Lothar, Kircher, Dieter, Halasy-Wimmer, Georg, Rieth, Peter E., Bill, Karlheinz
• Primary Examiner(s): Butler, Douglas C.
• Application Number:
  US08/403,651
• Time in Patent Office: 539 Days
• Field of Search: 303/3, 303/6.01, 303/9, 303/119.2, 303/9.61, 303/14-20, 303/119.1, 303/113.4, 303/DIG. 3, 303/DIG. 4, 303/115.2, 303/114.1, 303/113.3, 303/113.2, 180/65.1, 180/65.3, 180/165, 180/305-308, 180/197, 188/156, 188/158, 188/159, 188/106 P, 188/355-360, 60/545, 60/565, 60/554, 364/426.01, 364/426.02, 364/424.01
• US Class Current: 303/3
• CPC Class Codes: B60L 2220/44 Wheel Hub motors, i.e. integrated in the wheel hub
• CPC Class Codes: B60L 2250/26 by pedal actuation
• CPC Class Codes: B60L 2260/28 Four wheel or all wheel drive
• CPC Class Codes: B60L 7/26 Controlling the braking effect
• CPC Class Codes: B60T 13/586 the retarders being of the electric type
• CPC Class Codes: B60T 13/665 the systems being specially adapted for transferring two or more command signals, e.g. railway systems B60T13/662 takes precedence
• CPC Class Codes: B60T 13/745 acting on a hydraulic system, e.g. a master cylinder
• CPC Class Codes: B60T 7/042 by electrical means, e.g. using travel or force sensors
• CPC Class Codes: B60T 8/267 for hybrid systems with different kind of brakes on different axles
• CPC Class Codes: B60T 8/4077 Systems in which the booster is used as an auxiliary pressure source
• CPC Class Codes: Y10S 303/03 Electrical pressure sensor

Abstract

A brake system for automotive vehicles with electric drive is operable by an actuating pedal and uses hydraulic friction brakes to augment the braking effect generated by the electric drive motors. The coaction of the drive motors with the hydraulic friction brakes is controlled by an electronic controller. In order to largely conform the pedal characteristics of the mentioned brake system to that of a standard passenger car, an actuating pedal (5) is in force-transmitting and travel-transmitting connection with a spring (8) exhibiting a predetermined characteristic curve, and the master brake cylinder (11), uncoupled from the actuating pedal (5), is operable by an electromagnet (9) which is responsive to the controller (70). If the master brake cylinder accommodates two pressure cheers, a single valve is arranged in or on the master cylinder housing, and acts as both a bypass valve and a differential-pressure valve.

Claims

1. A brake system for automotive vehicles with electric drive which is operable by an actuating pedal cooperating with an actuating rod, comprising at least one electric drive motor and hydraulic friction brakes which are connected to a master brake cylinder, means for determining a pressure prevailing in the master brake cylinder, a first control device to which the output signal of a sensor for determining the actuating condition of the actuating pedal is fed, and a second control device, responsive to said first control device, for controlling the electric drive motor, characterized in that the actuating pedal is in force-transmitting/travel-transmitting connection with a spring having a predefinable characteristic curve, and in that the master brake cylinder, uncoupled from the actuating pedal, is operable by an electromagnet drivable by the first control device.

2. A brake system as claimed in claim 1, characterized in that the electromagnet is arranged coaxially to the master brake cylinder such that its armature radially embraces a piston rod operating the master cylinder piston and is axially abutting on a collar of larger diameter provided thereon.

3. A brake system as claimed in claim 2, characterized in that the spring is arranged such that it can be uncoupled from the actuating pedal in terms of effect.

4. A brake system as claimed in claim 3, characterized in that the actuating rod carries a plate that cooperates with a second electromagnet which can be driven on actuation and on which the spring takes support.

5. A brake system as claimed in claim 4, characterized in that the sensor for determining the actuating position of said actuating pedal is a brake light switch cooperating with the actuating pedal and the second electromagnet can be driven by the controller or by the brake light.

6. A brake system as claimed in claim 4, characterized in that the plate is movable into engagement with the piston rod.

7. A brake system as claimed in claim 4, characterized in that a second spring is interposed between the armature of the electromagnet and the plate.

8. A brake system as claimed in claim 3, the master brake cylinder being provided with a pressure fluid supply reservoir, characterized in that the electromagnet is arranged so as to be axially slidable within limits and cooperates with a hydraulic piston which confines a hydraulic chamber, the connection of which with the pressure fluid supply reservoir can be shut off on actuation, and in that the spring is supported on the electromagnet.

9. A brake system as claimed in claim 8, characterized in that the piston is designed as an annular piston and bounds the chamber designed as an annular chamber in a flange adapted to be fitted preferably to a body wall of the automotive vehicle, in which flange a valve is arranged which is preferably open in its de-energized state and shuts off the annular chamber.

10. A brake system as claimed in claim 9, characterized in that the sensor for determining the actuating condition of the actuating pedal is a brake light switch cooperating with the actuating pedal and the valve can be driven by the first controller or by the brake light switch cooperating with the actuating pedal.

11. A brake system as claimed in claim 10, characterized in that the master cylinder housing is made of plastics and is designed integrally with the pressure fluid supply reservoir.

12. A brake system as claimed in claim 11, characterized in that the connection between the annular chamber and the pressure fluid supply reservoir is formed by two bores provided in the flange as well as by a tubular pressure fluid duct which is shaped at the pressure fluid supply reservoir and connects to one of the bores.

13. A brake system as claimed in claim 12, characterized in that the master brake cylinder is coupled to the flange by the intermediary of the automobile body wall.

14. A brake system as claimed in claim 13, characterized in that the flange and the electromagnet form an assembly unit which carries the first control device.

15. A brake system as claimed in claim 14, characterized in that the master cylinder piston is designed as a plunger piston and is slidably guided in a sliding guide arranged in the master cylinder housing.

16. A brake system as claimed in claim 15, characterized in that the sliding guide serves as an axial stop for the master cylinder piston, on the one hand, and as an abutment surface for a resetting spring biassing the master cylinder piston, on the other hand.

17. A brake system as claimed in claim 15, characterized in that the sliding guide is designed as a sleeve provided with an external thread which is screwed into the master cylinder housing.

18. A brake system as claimed in claim 17, characterized in that the actuating rod is movable into engagement with a piston rod actuating the master cylinder piston.

19. A brake system as claimed in claim 18, characterized in that a device for sensing the switch condition of the valve is provided.

20. A brake system as claimed in claim 19, characterized in that the valve is designed as a solenoid valve, the device sensing variations of the inductivity of its coil which are caused by variations of the switch condition of the valve.

21. A brake system as claimed in claim 20, characterized in that the sensor for determining the actuating condition of the actuating pedal is a pressure sensor which is connected to the hydraulic chamber.

22. A brake system as claimed in claim 21, characterized in that the master brake cylinder is designed as a tandem master cylinder.

23. A brake system as claimed in claim 1, characterized in that the actuating rod carries a plate on which the spring is supported.

24. A brake system as claimed in claim 1, characterized in that the means for determining the pressure prevailing in the master brake cylinder is a pressure sensor.

25. A brake system as claimed in claim 1, characterized in that the means for determining the pressure prevailing in the master brake cylinder is a magnetic field sensor sensing the magnetic field of the electromagnet.

26. A brake system for automotive vehicles having electric drive comprising:

an actuating pedal;

an actuating rod coupled to said actuating pedal and movable in response to said actuating pedal;

a plurality of vehicle wheels;

at least one electric drive motor for driving and braking said plurality of vehicle wheels;

a master brake cylinder having a master brake cylinder piston which is uncoupled from the actuating pedal until said actuating pedal has travelled a threshold distance;

a plurality of hydraulic friction brakes connected to said master brake cylinder and individually associated with said plurality of vehicle wheels for braking said plurality of vehicle wheels;

means for determining a pressure prevailing in said master brake cylinder;

a sensor for determining the actuating position of said actuating pedal and for generating actuating pedal position signals;

a first control device responsive to said actuating pedal position signals for generating first control signals;

a first electromagnet responsive to said first control device for actuating said master brake cylinder piston;

a second control device responsive to said first control signals for generating second control signals to control said at least one electric drive motor; and

a spring, coupled to said actuating pedal, having a predetermined characteristic curve for simulating a reaction force caused by hydraulic braking to said actuating pedal.

27. A brake system as claimed in claim 26, further comprising:

a piston rod coupled to said master brake cylinder piston for actuating said master brake cylinder piston having a collar of larger diameter;

an armature, movable in response to said first electromagnet, radially embracing said piston rod and axially abutting on said collar; and

wherein said first electromagnet is arranged coaxially with said master brake cylinder.

28. A brake system as claimed in claim 27, further comprising a plate carried by said actuating rod and on which said spring is supported.

29. A brake system as claimed in claim 28, wherein said plate is movable into engagement with said piston rod.

30. A brake system as claimed in claim 28, further comprising a second spring interposed between said armature and said plate.

31. A brake system as claimed in claim 27, wherein said first electromagnet is axially slidable within limits and and said spring is supported on said first electromagnet and further comprising:

a pressure fluid supply reservoir formed with said master brake cylinder for supplying pressure fluid;

a hydraulic piston which confines a hydraulic chamber in pressure fluid communication with said pressure fluid supply reservoir; and

means for selectively preventing pressure fluid flow between said hydraulic chamber and said pressure fluid supply reservoir on actuation of said actuation pedal during electric braking.

32. A brake system as claimed in claim 31, further comprising a flange adapted to be fitted to a body wall of the automotive vehicle and wherein:

said hydraulic piston is an annular piston;

said hydraulic chamber is an annular chamber; and

said means for preventing pressure fluid flow are a valve arranged in said flange which is open in its de-energized state.

33. A brake system as claimed in claim 32, wherein said valve responds to said first control device.

34. A brake system as claimed in claim 33, wherein said flange and said electromagnet form an assembly unit which carries said first control device.

35. A brake system as claimed in claim 33, further comprising a device for sensing the switch condition of said valve.

36. A brake system as claimed in claim 35, wherein said valve is a solenoid valve having a coil with an inductivity which is variable dependent on the switch position of said valve, and said device senses variations of the inductivity of the coil.

37. A brake system as claimed in claim 36, wherein said sensor for determining the actuating position of said actuating pedal is a pressure sensor which is connected to said hydraulic chamber.

38. A brake system as claimed in claim 32, wherein:

said sensor for determining the actuating position of said actuating pedal is a brake light switch responsive to said actuating pedal; and

said valve responds to said brake light switch responsive.

39. A brake system as claimed in claim 32, wherein said master brake cylinder is defined by a master brake cylinder housing which is made of plastic and is designed integrally with said pressure fluid supply reservoir.

40. A brake system as claimed in claim 39, wherein said master brake cylinder piston is designed as a plunger piston and further comprising a sliding guide arranged in the master cylinder housing in which said master brake cylinder piston is slidably guided.

41. A brake system as claimed in claim 40, further comprising a resetting spring for biassing the master brake cylinder piston and wherein said sliding guide serves as an axial stop for said master brake cylinder piston and as an abutment surface for said resetting spring.

42. A brake system as claimed in claim 40, wherein said sliding guide is designed as a sleeve provided with an external thread which is screwed into said master cylinder housing.

43. A brake system as claimed in claim 42, wherein said actuating rod is movable into engagement with said piston rod.

44. A brake system as claimed in claim 32, wherein the connection between said annular chamber and said pressure fluid supply reservoir is formed by two bores provided in said flange and by a tubular pressure fluid duct which is shaped at the pressure fluid supply reservoir and connects to one of the bores.

45. A brake system as claimed in claim 32, wherein said master brake cylinder housing is coupled to said flange by the body wall of the automotive vehicle.

46. A brake system as claimed in claim 26, further comprising:

a plate carried by said actuating rod and on which said spring is supported; and

a second electromagnet adjacent said plate.

47. A brake system as claimed in claim 46, wherein said sensor for determining the actuating position of said actuating pedal is a brake light switch responsive to said actuating pedal, and wherein said second electromagnet responds to said first control device.

48. A brake system as claimed in claim 26 wherein said master brake cylinder is designed as a tandem master cylinder.

49. A brake system as claimed in claim 26, wherein said means for determining a pressure prevailing in said master brake cylinder are a pressure sensor.

50. A brake system as claimed in claim 26, wherein said means for determining a pressure prevailing in said master brake cylinder are a magnetic field sensor for sensing the magnetic field of said first electromagnet.