Brake unit for motor vehicles with electric drive

• US 5,769,509 A
• Filed: 11/01/1995
• Issued: 06/23/1998
• Est. Priority Date: 05/03/1993
• Status: Expired due to Term

• Current Assignee: ITT Automotive Europe GmbH
• Original Assignee: ITT Automotive Europe GmbH
• Inventors: Feigel, Hans-Jorg, Berthold, Thomas, Graber, Johannes, Kircher, Dieter
• Primary Examiner(s): Graham, Matthew C.
• Application Number:
  US08/545,749
• Time in Patent Office: 965 Days
• Field of Search: 303/3, 303/15, 303/116.1, 303/116.2, 303/152, 180/65.1-65.4, 180/65.8, 180/165
• US Class Current: 303/152
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/461 Speed
• CPC Class Codes: B60L 2240/463 Torque
• CPC Class Codes: B60L 2240/465 Slip
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 2250/10 by alarm
• CPC Class Codes: B60L 2250/16 by display
• CPC Class Codes: B60L 2250/26 by pedal actuation
• CPC Class Codes: B60L 3/0076 relating to braking
• CPC Class Codes: B60L 3/0084 relating to control modules
• CPC Class Codes: B60L 3/0092 with use of redundant elements for safety purposes
• CPC Class Codes: B60L 3/04 Cutting off the power supply under fault conditions protective devices and circuit arrangements in general H01H; H02H
• CPC Class Codes: B60L 3/108 whilst braking, i.e. ABS
• CPC Class Codes: B60L 7/12 for vehicles propelled by dc motors
• CPC Class Codes: B60L 7/26 Controlling the braking effect
• CPC Class Codes: B60T 1/10 by utilising wheel movement for accumulating energy, e.g. driving air compressors
• CPC Class Codes: B60T 13/586 the retarders being of the electric type
• CPC Class Codes: B60T 2270/602 : ABS features related thereto
• CPC Class Codes: B60T 2270/604 : Merging friction therewith; Adjusting their repartition
• CPC Class Codes: B60T 8/347 : 3 Channel systems B60T8/345 takes precedence
• CPC Class Codes: B60T 8/4072 : Systems in which a driver input signal is used as a control signal for the additional fluid circuit which is normally used for braking
• CPC Class Codes: B60T 8/4275 : Pump-back systems
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

A brake unit for motor vehicles with electric drive with a hydraulic pressure transducer and hydraulic friction brakes to increase the brake effect applied by the electric drive motor. The cooperation of the electric drive motor with the hydraulic friction brakes is controlled by an electronic controller. To increase the reliability of operation of the brake unit by making possible the buildup of hydraulic pressure in the friction brakes associated with the driven axle in the case of a failure of the electronic controller or of the entire electric system of the vehicle, the pressure transducer is arranged as a two-circuit main brake cylinder, to the first pressure space of which the friction brakes acting on the nondriven axle, and to the second pressure space of which the friction brakes acting on the driven axle are connected, wherein the connection between the second pressure space and the friction brakes acting on the driven axle is by at least one shut-off valve, which can be switched over electrically and is open in the currentless state.

Claims

1. Brake unit for motor vehicles with an electric drive motor and with a driven axle and a nondriven axle, comprising

a) a two-circuit brake pressure actuator, which can be actuated by means of a brake pedal, and to which friction brakes acting on the driven axle as well as on the nondriven axle are connected;

b) an electro-regenerative brake system, which uses the electric drive motor of the motor vehicle for braking and energy recovery; and

c) an electronic controller,which receives information on the state of actuation of said brake pressure actuator, the brake pressure brought about by the actuation, and the velocity of the vehicle, and evaluates it for controlling both the electric drive motor and said friction brakes acting on the driven axle,

characterized in that;

(a) said friction brakes acting on the nondriven axle are connected to a first pressure space of said brake pressure actuator, and said friction brakes acting on the driven axle are connected to a second pressure space of said brake pressure actuator, wherein the connection between said second pressure space and said friction brakes acting on the driven axle is performed via at least one shut-off valve, which can be switched over electrically and is open in the currentless state, and said friction brakes acting on the driven axle can be connected to a hydraulic energy supply unit or auxiliary pressure source via pressure control units, which can be switched over electrically; and

(b) a hydraulic connection, which can be shut off by means of a second shut-off valve, which can be switched over electrically, is provided between said friction brakes acting on the driven axle.

2. Brake unit in accordance with claim 1, characterized in that said brake pressure actuator is designed as a tandem main brake cylinder.

3. Brake unit in accordance with claim 2, characterized in that a pressure sensor, responsive to actuation of the brake unit, is connected to said second pressure space of said tandem main brake cylinder.

4. Brake unit in accordance with claim 1, characterized in that said second shut-off valve is designed as a valve which is open in the currentless state.

5. Brake unit in accordance with claim 1, wherein pressure sensors detecting the hydraulic pressure in the friction brakes acting on the driven axle are provided, characterized in that said pressure sensors are connected to sections of said hydraulic connection, which are located between said friction brakes and said second shut-off valve.

6. Brake unit in accordance with claim 5, characterized in that said pressure control units are connected to said sections of said hydraulic connection which are located between said friction brakes and said second shut-off valve.

7. Brake unit in accordance with claim 6, characterized in that said pressure control units are formed by current-controlled pressure relief valves.

8. A brake unit for a motor vehicle having an electric drive motor, a driven axle and a nondriven axle, said brake unit comprising:

a brake pedal;

a brake pressure actuator actuated by said brake pedal and having a first pressure space and a second pressure space;

a first pair of friction brakes adapted to act on the driven axle;

first connecting means for connecting said first pair of friction brakes to said second pressure space of said brake pressure actuator, said first connecting means including at least one electrically switchable shut-off valve which is open in the currentless state, a hydraulic connection between said friction brakes acting on the driven axle, and a second electrically switchable shut-off valve for closing said hydraulic connection;

a second pair of friction brakes adapted to act on the nondriven axle and connected to said first pressure space of said brake pressure actuator;

a hydraulic energy supply unit;

second connecting means for connecting said second pair of friction brakes to said hydraulic energy supply unit, said second connecting means including first and second electrically switchable pressure control units;

an electro-regenerative brake system for braking and energy recovery; and

an electronic controller responsive to information on;

(a) the state of actuation of the said brake pressure actuator,

(b) the brake pressure brought about by the actuation, and

(c) the velocity of the vehicle,

for evaluating said information and for controlling;

(a) said friction brakes acting on the driven axle, and

(b) the electric drive motor to actuate said electro-regenerative brake system.

9. A brake unit according to claim 8 wherein said brake pressure actuator is a tandem main brake cylinder.

10. A brake unit according to claim 9 further including a pressure sensor connected to said second pressure space of said tandem main brake cylinder for sensing actuation of said brake pedal.

11. A brake unit according to claim 8 wherein said second shut-off valve is open in the currentless state.

12. A brake unit according to claim 8 wherein said hydraulic connection has first and second sections respectively located between said second shut-off valve and said friction brakes acting on the driven axle and said brake unit further includes pressure sensors connected to said sections of said hydraulic connection between said second shut-off valve and said friction brakes acting on the driven axle for detecting hydraulic pressure in the friction brakes acting on the driven axle.

13. A brake unit according to claim 12 wherein said pressure control units are connected to said sections of said hydraulic connection which are located between said second shut-off valve and said friction brakes acting on said driven axle.

14. A brake unit according to claim 13 wherein said pressure control units include current-controlled pressure relief valves.

15. A process for checking the ability of a hydraulic energy supply unit to operate in a brake unit of a motor vehicle having an electric drive motor, a driven axle, and a nondriven axle, and said brake unit having:

a brake pedal,

a brake pressure actuator actuated by said brake pedal and having a first pressure space and a second pressure space,

a first pair of friction brakes adapted to act on the driven axle,

first connecting means for connecting said first pair of friction brakes to said second pressure space of said brake pressure actuator, said first connecting means including at least one electrically switchable shut-off valve which is open in the currentless state,

a second pair of friction brakes adapted to act on the nondriven axle and connected to said first pressure space of said main brake cylinder,

a hydraulic energy supply unit including;

(a) a first circuit,

(b) a hydraulic valve arrangement for connecting said first circuit to said friction brakes acting on the nondriven axle,

(c) a second circuit, and

(d) a high-pressure accumulator connected to said friction brakes acting on the driven axle by said pressure control units,

second connecting means for connecting said second pair of friction brakes to said hydraulic energy supply unit, said second connecting means including first and second electrically switchable pressure control units,

an electro-regenerative brake system for braking and energy recovery, and

an electronic controller responsive to information on;

(a) the state of actuation of the said brake pressure actuator,

(b) the brake pressure brought about by the actuation, and

(c) the velocity of the vehicle,

for evaluating said information and for controlling;

(a) said friction brakes acting on the driven axle, and

(b) the electric drive motor to actuate said an electro-regenerative brake system,

said process including the steps of;

(a) measuring the charging time during each charging process,

(b) comparing the measured charging time with a predetermined desired charging time, and

(c) displaying a deviation of the difference between the measured charging time and the predetermined desired charging time from a preset difference.

16. Brake unit for motor vehicles with an electric drive motor and with a driven axle and a nondriven axle, comprising

a) a two-circuit brake pressure actuator, which can be actuated by means of a brake pedal, and to which friction brakes acting on the driven axle as well as on the nondriven axle are connected;

b) an electro-regenerative brake system, which uses the electric drive motor of the motor vehicle for braking and energy recovery; and

c) an electronic controller, which receives information on the state of actuation of said brake pressure actuator, the brake pressure brought about by the actuation, and the velocity of the vehicle, and evaluates it for controlling both the electric drive motor and said friction brakes acting on the driven axle,

characterized in that;

(a) said friction brakes acting on the nondriven axle are connected to a first pressure space of said brake pressure actuator, and said friction brakes acting on the driven axle are connected to a second pressure space of said brake pressure actuator, wherein the connection between said second pressure space and said friction brakes acting on the driven axle is performed via at least one shut-off valve, which can be switched over electrically and is open in the currentless state, and said friction brakes acting on the driven axle can be connected to a hydraulic energy supply unit or auxiliary pressure source via pressure control units, which can be switched over electrically; and

(b) said hydraulic energy supply unit is formed by a two-circuit motor-pump unit, the first circuit of which is connected to said friction brakes acting on the nondriven axle via a hydraulic valve arrangement, and the second circuit of which is connected to a high-pressure accumulator, which is connected to said friction brakes acting on the driven axle via said respective pressure control units.

17. A brake unit for a motor vehicle having an electric drive motor, a driven axle and a non-driven axle, said brake unit comprising:

a brake pedal;

a brake pressure actuator actuated by said brake pedal and having a first pressure space and a second pressure space;

a first pair of friction brakes adapted to act on the driven axle;

first connecting means for connecting said first pair of friction brakes to said second pressure space of said brake pressure actuator, said first connecting means including at least one electrically switchable shut-off valve which is open in the currentless state;

a second pair of friction brakes adapted to act on the nondriven axle and connected to said first pressure space of said brake pressure actuator;

a hydraulic energy supply unit including a two-circuit motor-pump unit comprising;

(a) a first circuit,

(b) a hydraulic valve arrangement for connecting said first circuit to said friction brakes acting on the nondriven axle,

(c) a second circuit, and

(d) a high-pressure accumulator connected to said friction brakes acting on the driven axle by pressure control units;

second connecting means for connecting said second pair of friction brakes to said hydraulic energy supply unit, said second connecting means including first and second electrically switchable pressure control units;

an electro-regenerative brake system for braking and energy recovery; and

an electronic controller responsive to information on;

(a) the state of actuation of the said brake pressure actuator,

(b) the brake pressure brought about by the actuation, and

(c) the velocity of the vehicle,

for evaluating said information and for controlling;

(a) said friction brakes acting on the driven axle, and

(b) the electric drive motor to actuate said electro-regenerative brake system.