Closed loop speed control of ABS pump motor utilizing variable duty cycle and frequency
AssigneeKelsey-Hayes Company
InventorWei Zhan
Life of this patent
Estimating the term…
Abstract
The speed of a pump motor in a vehicle brake control system is controlled by comparing an actual pump motor speed to a threshold speed. The actual pump motor speed is determined by measuring the pump back emf while the motor is de-energized. If the actual pump motor speed is greater than the threshold speed, the motor remains de-energized. If the actual pump motor speed is less than the threshold speed, the pump motor is energized with a pulse width modulated voltage having a variable duty cycle and a variable frequency which are functions of the difference between the actual pump motor speed and the threshold speed.
Claims19
A system for controlling at least one vehicle wheel brake comprising:
- a pump which supplies pressurized brake fluid to the controlled wheel brake;
- a motor connected to said pump for driving said pump;
- a control valve connected between said pump and the controlled wheel brake, said control valve operable to control the flow of pressurized brake fluid from said pump to the controlled wheel brake;
- a sensor for measuring the speed of said pump motor;
- and
- a controller electrically connected to said pump motor speed sensor and said pump motor, said controller operative to provide power to said pump motor and to control said pump motor speed as a function of said sensed pump motor speed by de-energizing said pump motor when said sensed pump motor speed is greater than a motor speed threshold and to maintain said pump motor in a de-energized state while said sensed pump motor speed is greater than said motor speed threshold.
A process for controlling the speed of a pump motor comprising the steps of:
- (a) providing a pump for supplying pressurized brake fluid to at least one vehicle wheel brake, the pump being driven by a motor which is connected to a controller, the controller being operative to supply power to the pump motor, the controller also connected to a speed sensor for monitoring the pump motor speed;
- (b) operating the pump motor for a predetermined time period;
- (c) sensing the actual pump motor speed;
- (d) comparing the sensed pump motor speed to a predetermined pump motor speed threshold;
- (d) de-energizing the pump motor if the sensed pump motor speed is greater than the pump motor speed threshold
- (f) continuing to sense the actual pump motor speed;
- and
- (g) continuing to compare the sensed pump motor speed to the pump motor speed threshold and maintaining the pump motor in a de-energized state while the sensed pump motor speed remains greater than the pump motor speed threshold.
Dependencies are inferred from the claim text.