Patent ID: 6652039
Filing Date: 2003-11-25
Classification: B60T,Y10S

Abstract:
In a vehicle braking system having a master cylinder for selectively supplying a first hydraulic braking pressure through a primary hydraulic brake circuit to a plurality of wheel brake cylinders; an electronic control unit for monitoring vehicle operation; and a secondary hydraulic circuit connected to said primary hydraulic brake circuit and including a pump for selectively supplying a second hydraulic braking pressure to wheel brake cylinders, said secondary hydraulic circuit having an accumulator for receiving said first hydraulic fluid from said wheel brakes and dispensing said second hydraulic fluid to wheel brake cylinders and a plurality of valves under control of the electronic control unit to selectively transfer hydraulic fluid to and from the accumulator, a process of controlling the secondary hydraulic circuit of the vehicle braking system during aberrant wheel behavior comprising the steps of:creating a magnetic field adjacent the accumulator; modifying the magnetic field in accordance with changes in the fluid volume within the accumulator; monitoring changes in the magnetic field; translating the magnetic field changes into an indication of accumulator fluid volume; and utilizing the volume indication in controlling operation of the secondary circuit to change said volume of fluid in said accumulator during an aberrant wheel behavior such that a sufficient reserve volume of hydraulic fluid is retained in said accumulator to receive said first hydraulic fluid during an anti-lock braking event and to supply a pump with said second hydraulic fluid during a traction control event.