Fluid Pressure Control of Hydraulic Unit For TCS Control

FLUID PRESSURE CONTROL OF HYDRAULIC UNIT FOR TCS CONTROL





1) Pressure-rise conditions
When the driving wheels slip, TCS1 and TCS2 are operated and the hydraulic oil channel is switched over to TCS mode. At the same time the motor pump operates and sucks in brake fluid from the M/C reservoir, and hydraulic pressure is imparted to the W/C via FRI and FLI. This generates braking force and suppresses the wheel slip.





2) Pressure-hold conditions
Pressure-hold mode is entered in order to focus temporarily on the behavior of the wheels following pressure rise/drop control and to maintain a proper degree of slip conditions due to engine output drop control and pressure rise/drop control of brake pressure. Under these conditions FRI, FRO- FLI, FLO are in hold conditions, and the motor pump pressure-generating side is cut off from the W/C side. The motor continues to rotate at this time and the pressure inside the H/U rises. Once it exceeds the stipulated value, however, PLV is released and the pressure is relieved to the suction circuit.





3) Pressure-drop conditions
When the driving wheel slip is reduced, FRI and FRO are turned ON and FLI and FLO are also ON, and the fluid pressure channels enter pressure-drop conditions. The W/C pressure is released to the M/C reservoir and the braking force is alleviated and vehicle acceleration conditions are maintained.