A valve mechanism is provided in a hydraulic line which connects a master cylinder of a brake system and a brake provided for a driving wheel of a vehicle. When the slip of the driving wheel is larger than a predetermined value, the valve mechanism is selectively moved between a position where it directly applies brake fluid from the master cylinder to the brake and a position where it returns brake fluid discharged from the brake to an oil reservoir, thereby controlling the driving torque of the driving wheel to converge the slip of the driving wheels to a proper level. An oil pump is operated to return the brake fluid in the oil reservoir to the master cylinder when the valve mechanism is operated to effect the slip control. While the brake pedal is in the released state, the oil pump is kept operated during the slip control and for a predetermined time after interruption of the slip control so that the brake fluid in the oil reservoir is returned to the master cylinder substantially completely. When the brake pedal is depressed while the slip being effected, the slip control is ended and the oil pump is stopped. After the brake pedal is released, the oil pump is operated for a predetermined time.

Slip control system for vehicle

An anti-skid control method for an anti-skid control device comprising two pressure medium lines installed between the master cylinder and the return pathway of the pressure medium with an inlet valve, selector valve, and discharge valve arranged in series in each of the two pressure medium lines, a front wheel brake being connected between the inlet valve and the selector valve of each pressure medium line and a diagonally opposite rear wheel brake being connected between the same selector valve and the discharge valve of that pressure medium line, and a control circuit which controls the front and rear wheel brake pressures through the pressure medium lines. The rotational speeds of each front and rear wheel are determined. The state of traction of each front and rear wheel is judged by the control circuit. The appropriate inlet valve, selector valve, discharge valve and combination thereof are activated to control locking and slippage of each front and rear wheel. In addition, the control circuit opens the inlet valves when the selector valves open to increase the brake pressure of the rear wheels to compensate for the accompanying reduction in pressure of the front wheels.

Anti-skid control method

A traction control device operates to determine the speed of each of the left and right drive wheels of a vehicle, determine the speed of each of the left and right passive wheels of the vehicle, calculate the actual slip rate of the drive wheels of the vehicle directly based on the measurements of the speeds for the drive and passive wheels, establish a target slip rate and control the driving condition of the vehicle by making the actual slip rate equal the target slip rate. The actual slip rate is matched to the target slip rate by controlling engine output and braking power. The step of controlling the driving condition of the vehicle by controlling the engine output and the braking power is carried out according to the time differential of the difference between the actual slip rate and the target slip rate at least until the actual slip rate matches the target slip rate for the first time. After the actual slip rate has matched the target slip rate at least once, the step of controlling is carried out according to the proportion of the difference between the actual and the target slip rates.

Traction control device for vehicles

A traction control method for a vehicle, includes the steps of comparing the amount of driven wheel speed (V W ) changed per unit time with a reference deceleration (ΔV R- ) determined in correspondence to the lowest deceleration on a road surface of a lowest frictional coefficient which can be usually supposed, setting the vehicle speed (V R ) equal to the driven wheel speed (V W ), if the amount of driven wheel speed (V W ) changed per unit time indicates a deceleration less than a reference deceleration (V R- ); setting the vehicle speed (V R ) equal to the last determined vehicle speed (V R (n-1)) corrected by the reference deceleration, if the amount of driven wheel speed (V W ) changed per unit time indicates a deceleration greater than or equal to the reference deceleration (ΔV R- ); determining a slipping tendency of a driving wheel in a driving state at least in part by comparing a reference speed (V RH , V RL ) obtained on the basis of a vehicle speed (V R ) with a driving wheel speed; and suppressing the driving torque in accordance with a determined slipping tendency of a driving wheel in the driving state. Further, the amount of driven wheel speed (V W ) changed per unit time may also be compared to a reference acceleration (ΔV R+ ).

Traction control method for vehicle

A brake pressure control mechanism for establishing a pressure level in a brake actuator includes a valve controlled by the current in a solenoid coil. The current in the coil is controlled in a first mode by switching the current in the coil off and on and allowing the current to increase and decay in the normal manner. However, when a fast decrease in brake pressure is demanded, the fly-back voltage across the coil is allowed to rapidly increase to a level greater than and in opposition to the voltage applied to the coil, thereby quickly driving the current lower. Current is driven to zero in the case of a fast brake pressure decay being demanded by the adaptive braking system or when the vehicle operator releases the brakes. When the error signal demands a fast decay, the fast decay mode is initiated and then returned to the normal control when the error between the demanded braking pressure and the pressure corresponding to the current of the coil is back within predetermined limits.

Solenoid current driver circuit

A method for traction control of a vehicle, includes detecting a slipping tendency of a drive wheel in a driven state, and controlling the braking force of a drive wheel brake device in an increasing and decreasing manner in accordance with the degree of the detected slipping tendency, wherein a rapid increase mode of rapidly increasing the braking force of the drive wheel brake device and a slow increase mode of slowly increasing the braking force can be switched from one to the other, so that at an initial stage in increasing the braking force of the drive wheel brake device on the basis of the decision that the drive wheel is in an excessive slipping tendency, the braking force is increased in the rapid increase mode.

Takashi C

Papers

Method for traction control of vehicle