Honda HR-V: VSA System Description - ABS Control

When wheel speed is significantly reduced from estimated vehicle speed, the VSA modulator-control unit closes the inlet valve and opens the outlet valve momentarily to reduce brake fluid pressure and the pump motor starts to run. As wheel speed increases, the VSA modulator-control unit maintains brake fluid pressure by keeping the inlet valve closed. Brake fluid pressure is increased when wheel speed matches the estimated speed of the vehicle. The VSA modulator-control unit repeats this valve control operation to control the ABS function.

Split Control

When one drive tire is on a low traction surface like a gravel shoulder, while the other drive tire is on a high traction surface like a paved highway, applying the brakes causes increased driving force on the high traction surface. This increased driving force on the high traction surface results in vehicle instability. To maintain vehicle stability during this scenario, the VSA modulator unit actively controls the driving force by adjusting the hydraulic fluid pressure, as needed, for each wheel.

VSA SYSTEM DESCRIPTION - AUTOMATIC BRAKE HOLD

The automatic brake hold keeps the brakes applied even when the brake pedal is released. Once the vehicle comes to a stop in heavy traffic or at traffic lights, the driver does not need to continue pressing the brake pedal.

The automatic brake hold is canceled when the the accelerator pedal is pressed, and returns to the stand by mode. If the automatic brake hold is applied for an extended time, about ten minutes, the electric parking engages to hold the vehicle.

Conditions for maintaining/canceling the automatic brake hold operation in the M/T model is different from the AT and CVT model.

Refer to the chart below for more information about the conditions to apply and cancel the automatic brake hold.

VSA SYSTEM DESCRIPTION - BRAKE ASSIST CONTROL

The brake assist control constantly monitors brake operation through the pressure sensor. If the pedal stroke speed and pedal stroke amount exceed the predetermined values like the driver is stepping on the brake pedal hard, it is considered to be emergency braking. When the system determines the driver is braking because of an emergency, the VSA modulator-control unit increases braking force compared to normal braking and shortens the braking distance.

VSA SYSTEM DESCRIPTION - EBD CONTROL

The EBD (electronic brake-force distribution) system actively controls the distribution of the front and rear braking forces to correspond with changes in the load condition and displacement of the load due to deceleration.

When rear wheel speed is less than the estimated vehicle speed, the VSA modulator-control unit closes the inlet valve to maintain brake fluid pressure. As wheel speed increases, the VSA modulator-control unit opens the inlet valve momentarily to increase the brake fluid pressure. When lower pressure is required, the modulator unit opens the outlet valve momentarily decreasing fluid pressure. The VSA modulator-control unit repeats this valve control operation to control the EBD function.

VSA SYSTEM DESCRIPTION - ENGINE DRAG TORQUE CONTROL

Downshifting on a slippery road may cause vehicle instability because the engine braking may lock up the wheels. When engine braking begins to cause the wheels to lock up, the engine drag torque control commands the PCM to increase the torque, helping to prevent tire slip.

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