Method and system for controlling brake pressure under low Mu braking surface conditions in a vehicular ABS
AssigneeEaton Corporation
InventorRichard J. Youngblood
Life of this patent
Estimating the term…
Abstract
Method and system for reducing the brake pressure rise rate under low Mu braking surface conditions by utilizing a vehicle reference speed to determine if the wheels are being over-braked. When over-braking occurs, the pressure rise rate is restricted by not allowing an ABS valve to go into an Apply state (approximately 100 psi/sec.), regardless of wheel acceleration levels. A Ramp state is used in place of the Apply state and the pressure rise is therefore limited to approximately 30 psi/sec. to improve wheel control. The Ramp duty cycle is also modified to provide the smallest pressure steps possible with the current valve hardware.
Claims8
In a vehicle, a method for controlling a brake pressure rise rate under low Mu braking surface conditions in a vehicular ABS, including an ABS valve to control the brake pressure rise rate, the method comprising the steps of:
- monitoring the speed of the vehicle wheels;
- generating a vehicle reference speed based on the highest wheel speed of the vehicle;
- decreasing the value of the vehicle reference speed over time;
- determining when the speed of one of the wheels is greater than the vehicle reference speed after the step of decreasing;
- correcting the vehicle reference speed when the speed of the one of the wheels is greater than the vehicle reference speed;
- and
- limiting the brake pressure rise rate when the speed of the one of the wheels is greater than the vehicle reference speed by a predetermined amount.
A system for controlling a brake pressure rise rae under low Mu braking surface conditions in a vehicular ABS including an ABS valve to control the brake pressure rise rate, the system comprising:
- means for monitoring the speed of the vehicle's wheels;
- means for generating a vehicle reference speed based on the highest wheel speed of the vehicle;
- means for decreasing the value of the vehicle reference speed over time;
- means for determining when the speed of one of the wheels is greater than the reference speed after the value of the vehicle reference speed has been decreased;
- means for correcting the vehicle reference speed when the speed of the one of the wheels is greater than the vehicle reference speed;
- and
- means for limiting the brake pressure rise rate when the speed of the one of the wheels is greater than the vehicle reference speed by a predetermined amount.
Dependencies are inferred from the claim text.