Patent ID: 6950738

Claim:
An automotive anti-lock control system comprising: a brake fluid pressure generator; a wheel brake attached to a wheel; a connection line for connecting the brake fluid pressure generator and the wheel brake; a release line for connecting a reservoir for reserving brake fluid and the wheel brake; a normally-opened electromagnetic valve interposed along the connection line; a normally-closed electromagnetic valve interposed along the release line; a wheel speed sensor for detecting the wheel speed of the wheel; and anti-lock controller which determines a lockup tendency of the wheel based on the wheel speed detected by the wheel speed sensor and controls the brake fluid pressure in a pressure decreasing mode where the normally-opened electromagnetic valve is closed and the normally-closed electromagnetic valve is opened, a holding mode where the normally-opened electromagnetic valve is closed and the normally-closed electromagnetic valve is closed, and a pressure increasing mode where the normally-opened electromagnetic valve is opened and the normally-closed electromagnetic valve is closed, wherein when in the pressure decreasing mode, a maximum current value resulting when the normally-opened electromagnetic valve is continuously turned on is 100, while a current value resulting when the normally-opened electromagnetic valve is turned off is 0, and the anti-lock controller includes a duty pressure increasing mode where predetermined values D 1 , D 2 each correspond to a percentage of the maximum current value to be applied to the normally-opened electromagnetic valve, the predetermined values D 1 , D 2 i) being related to the maximum current value in a relationship such as 100>D 1 >D 2 >0, ii) are repeatedly sequentially applied to the normally-opened electromagnetic valve at a predetermined time interval in the duty pressure increasing mode, and iii) are determined such that the range extending between D1 and D2 is approximately one third of the range defined between the a current value of 0 and the maximum current value.