Electric parking brake system for a vehicle

An electric parking brake system for a vehicle comprising in combination:

• a parking brake installed on a vehicle;
• an electromagnetic means for controlling application and release of said parking brake;
• a gradient sensor adapted to detect the gradient of the road on which the vehicle rests for sending out a signal indicative of the gradient detection
• a condition sensor adapted to detect the operating condition of the vehicle;
• a controller adapted to receive the signals from said condition sensor and said gradient sensor and to alternatively feed a brake-application command signal and a brake-release command to said electromagnetic means in accordance with the operating condition of the vehicle;
• at least one of the brake-applying operation and the brake-releasing operation of said electromagnetic means being variably controlled by said controller in accordance with the signal from said gradient sensor;
• and
• a time lag adjusting means operable to make greater the time lag between the time when the brake-release command signal is produced and the time when the brake-releasing operation of said electromagnetic means begins in accordance with increasing gradient of the road.

An electric parking brake system for a vehicle comprising in combination:

• a parking brake installed on a vehicle;
• an electromagnetic means for controlling application and release of said parking brake;
• a gradient sensor adapted to detect the gradient of the road on which the vehicle rests for sending out a signal indicative of the gradient detected;
• a condition sensor adapted to detect the operating condition of the vehicle;
• a controller adapted to receive the signals from said condition sensor and said gradient sensor and to alternatively feed a brake-application command signal and a brake-release command to said electromagnetic means in accordance with the operating condition of the vehicle;
• at least one other brake-applying operation and the brake-releasing operation of said electromagnetic means being variably controlled by said controller in accordance with the signal from said gradient sensor;
• said condition sensor comprising a speed sensor for detecting whether or not the speed of the vehicle is greater than a preset level;
• a main brake snesor for detecting whether a main brake is in or out of operation;
• an acceleration sensor for detecting whether an accelerator pedal is depressed or not;
• a position sensor for detecting whether or not a transmission is in a driving position, said controller being adapted to receive signals from each of said speed sensor, said main brake sensor, said acceleration sensor, and said position sensor and operable to send out a brake-application command signal to said electromagnetic means in cases where the signals of said speed sensor, main brake sensor, and acceleration sensor are received to indicate that the vehicle speed is less than said preset level, said main brake is in operation and said accelerator pedal is not depressed whereas said command-signal producing means sends out a brake-release command signal to said electromagnetic means in cases where the signals from said main brake sensor, acceleration sensor, and position sensor are received to indicate that said main brake is released, said accelerator pedal is depressed and the transmission is in the driving position, and a time-lag adjusting means operable to make greater the time lag between the time when the brake-release command signal is produced and the time when the brake-releasing operation of said electromagnetic means begins in accordance with increasing gradient of the road.

An electric parking brake system for a vehicle comprising in combination:

• a parking brake installed on a vehicle;
• an electromagnetic means for controlling application and release of said parking brake;
• a gradient sensor adapted to detect the gradient of the road on which the vehicle rests for sending out a signal indicative of the gradient detected;
• a condition sensor adapted to detect the operating condition of the vehicle;
• a controller adapted to receive the signals from said condition sensor and said gradient sensor and to alternatively feed a brake application command signal and a brake release command to said electromagnetic means in accordance with the operating condition of the vehicle;
• at least one of the brake-applying operation and the brake-releasing operation of said electromagnetic means being variably controlled by said controller in accordance with the signal from said gradient sensor;
• a switch means adapted to generate manual signals for brake-application and brake-release by manual operation, wherein said controller alternatively produces a brake-application command signal and a brake-release command signal on the basis of the output signal from said condition sensor and the operating position of said switch means;
• and
• a time-lag adjusting means operable to make greater the time lag between the time when the brake-release command signal is produced and the time when the brake-releasing operation of said electromagnetic means begins in accordance with increasing gradient of the road.