SLIP-CONTROLLED BRAKING SYSTEM FOR ELECTRICALLY DRIVEN MOTOR VEHICLES

• US 20140257664A1
• Filed: 09/27/2012
• Published: 09/11/2014
• Est. Priority Date: 09/28/2011
• Status: Active Grant

• Current Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Original Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Inventors: Chen, Zhenfu, Raste, Thomas, Lauer, Peter, Muntu, Matthias, Arbitmann, Maxim, Schmitz, Daniel
• Granted Patent: US 9,744,862 B2
• Time in Patent Office: Days
• US Class Current: 701/71
• CPC Class Codes: B60L 7/18 Controlling the braking effect B60L7/12, B60L7/14, B60L7/16 take precedence
• 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 13/746 and mechanical transmission of the braking action
• 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 2270/613 ESP features related thereto
• CPC Class Codes: B60T 7/107 with electrical power assistance
• CPC Class Codes: B60T 7/22 initiated by contact of vehicle, e.g. bumper, with an external object, e.g. another vehicle , or by means of contactless obstacle detectors mounted on the vehicle
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02
• CPC Class Codes: B60T 8/17551 determining control parameters related to vehicle stability used in the regulation, e.g. by calculations involving measured or detected parameters
• CPC Class Codes: B60T 8/1761 responsive to wheel or brake dynamics, e.g. wheel slip, wheel acceleration or rate of change of brake fluid pressure
• CPC Class Codes: B60T 8/1766 Proportioning of brake forces according to vehicle axle loads, e.g. front to rear of vehicle

Abstract

A braking system for a motor vehicle, including friction brakes on the wheels of at least one axle, the brakes controlled by a friction brake control device; at least one electric machine connected to at least one wheel and controlled by an electric drive control device; a brake pedal for detecting a deceleration request; a wheel-slip controlling device; and a torque distributing device. The devices for detecting a deceleration request are connected to the wheel-slip controlling device, the wheel-slip controlling device specifying target braking torques for each wheel according to the parameters of the deceleration request. The wheel-slip controlling device connected to a torque distributing device which is connected to the friction brake control device and the electric drive control device and which specifies friction brake requests to the friction brake control device and generator brake requests to the electric drive control device according to the target braking torques.

Claims

1. A brake system for a motor vehicle comprising friction brakes on the wheels of at least one axle, which friction brakes are actuated by a friction brake control device, at least one electric machine which is connected to at least one wheel and is actuated at least at times as a generator by an electric drive control device, means for detecting a deceleration request, and a wheel slip control device, wherein the means for detecting a deceleration request is/are connected to the wheel slip control device which predefines setpoint braking torques (M_wheel,req) for each wheel in accordance with the deceleration request (a_decel,req), wherein the wheel slip control device is connected to a torque distribution device which is connected to the friction brake control device and the electric drive control device and predefines friction braking requests (M_fric,req) to the friction brake control device and generator braking requests (M_reg,req) to the electric drive control device.

2. The brake system as claimed in claim 1, wherein the wheel slip control device is connected to a state observer which is connected to sensors for sensing at least the wheel speeds (v_wheel) of each individual wheel, the yaw rate ({dot over (Ψ

)}) and the lateral acceleration (a_lat), wherein at least the instantaneously present braking torques (M_wheel,inst) at the individual wheels are determined and taken into account in the predefinition of the setpoint braking torques (M_wheel,req).

3. The brake system as claimed in claim 2, further comprising a yawing moment control device which is connected to the state observer and to a steering angle sensor and which compares the setpoint yaw rate, determined at least on the basis of the steering angle, and a measured yaw rate, wherein wheel-specific setpoint braking torques (M_wheel,req) are determined in accordance with the comparison result and fed to the wheel slip control device.

4. The brake system as claimed in claim 1, wherein the torque distribution device is connected to the means for detecting a deceleration request and the splitting between the friction brake requests (M_fric,req) and the generator braking requests (M_reg,req) is carried out taking into account the current deceleration request (a_decel,req) and/or the current locking braking torque of the wheel and/or the velocity and/or the steering wheel angle and/or the lateral acceleration (a_lat).

5. The brake system as claimed in claim 1, wherein the electric drive control device transmits the currently applied generator braking torque or torques (M_reg,curr) and/or the maximum generator braking torque or torques (M_cap) which can be generated to the torque distribution device, and the splitting between the friction braking requests and the generator braking request or requests is carried out taking into account the generator braking torque or torques which is/are currently applied and/or the maximum generator torque or torques which can be generated.

6. The brake system as claimed in claim 1, wherein the means for detecting a deceleration request also comprise an interface with a vehicle data bus via which an electronic control device, which is connected, in particular, to one or more surroundings sensors, transmits a deceleration request.

7. The brake system as claimed in claim 1, wherein the friction brake control device, the wheel slip control device and the torque distribution device are integrated into an electronic control device and are preferably implemented entirely or partially as program code which is executed by a computing unit of the electronic control device.

12. The brake system as claimed in claim 1, wherein the means for detecting a deceleration request is a sensor for detecting activation of a brake pedal.

8. A method for controlling a brake system for a motor vehicle, comprising friction brakes on the wheels of at least one axle which friction brakes are actuated by a friction brake control device, and at least one electric machine which is connected to at least one wheel and can be operated as a generator, means for detecting a deceleration request, and a wheel slip control device, wherein the senor is connected to the wheel slip control device which predefines setpoint braking torques (M_wheel,req) for each wheel in accordance with the deceleration request (a_decel,req), wherein the wheel slip control device is connected to a torque distribution device which is connected to the friction brake control device and the electric drive control device and predefines friction braking requests (M_fric,req) to the friction brake control device and generator braking requests (M_reg,req) to the electric drive control device, the method comprising:

determining a current driving state by a state observer, wherein the current driving state comprises at least a current braking torque and at least one of two variables of a current wheel speed and a current slip for each individual wheel,

determining wheel-specific setpoint braking torques on the basis of a deceleration request taking into account the current driving state,

splitting the setpoint braking torques for the individual wheels into friction braking requests and a generator braking request/requests, and

activating the friction brakes according to the friction braking requests and operating the electric machine according to the generator braking request/requests.

9. The method as claimed in claim 8, wherein the generator braking request is determined in accordance with the current braking torque, wherein for a wheel which is connected to a generator the friction braking request is determined on the basis of a comparison of the setpoint braking torque with the generator braking request.

10. The method as claimed in claim 9, wherein a first electric machine is connected to at least two wheels, and the generator braking request to the first electric machine is selected as a predefined portion of the minimum current braking torque of the coupled wheels.

11. The method as claimed in claim 9, wherein at least one wheel is assigned an electric machine which is connected to no other wheel, and the generator braking request to the assigned machine is determined on the basis of a characteristic curve K(μ

) which is dependent on the estimated coefficient of friction μ

, preferably according to the relationship K(μ

)·

C·

M_wheel with a constant C and the current braking torque M_wheel at the wheel under consideration.