VSA System Description - Components

VSA Modulator

The VSA modulator unit consists of the inlet solenoid valve, the outlet solenoid valve, the VSA NO (normally open) solenoid valve, the VSA NC (normally closed) solenoid valve, the reservoir, the pump, the pressure sensor, and the pump motor. The hydraulic control has four modes; pressure intensifying, pressure retaining, pressure reducing, and pressure intensifying mode.

Courtesy of HONDA, U.S.A., INC.

Mode	VSA NOSolenoidValve	VSA NCSolenoidValve	InletSolenoidValve	OutletSolenoidValve	Brake Fluid
Pressure intensifying mode	open	closed	open	closed	Master cylinder fluid is pumped out to the caliper.
Pressure retaining mode	open	closed	closed	closed	Caliper fluid is retained by the inlet and outlet solenoid valves.
Pressure reducing mode	open	closed	closed	open	Caliper fluid flows through the outlet solenoid valve to the reservoir.

Mode	VSA NOSolenoidValve	VSA NCSolenoidValve	InletSolenoidValve	OutletSolenoidValve	Brake Fluid
Pressure intensifying mode (VSA)	closed (current control)	open	open	closed	Master cylinder fluid is pumped out by the pump through the VSA NC solenoid valve to the caliper. Caliper fluid pressure exceeds master cylinder pressure. The VSA modulator unit controls amount of intensified fluid pressure to respond to each mode through current control of VSA NO solenoid valve.

Wheel Speed Sensor

The VSA system uses 4 wheel speed sensors to monitor individual wheel speed. The wheel speed sensor is a semiconductor, Hall effect sensor, and detects the magnetic field of a magnetic encoder installed on the inner sealing surface of each hub and wheel bearing assembly. The frequency of the sensor output signal is proportional to the speed of the wheel and this signal information is sent to the VSA control unit.

Courtesy of HONDA, U.S.A., INC.