Braking force retaining unit

A braking force retaining unit for a hydraulic brake system in a vehicle, the hydraulic brake system comprising:

• a hydraulic brake circuit;
• a master cylinder in fluid communication with the circuit;
• at least one wheel cylinder in fluid communication with the circuit;
• and
• a break pedal operatively connected to the master cylinder;
• the brake force retaining unit comprising:
• a cut-off valve provided in the circuit disposed between the master cylinder and the at least one wheel cylinder;
• and
• a control unit for controlling opening and closing of the cut-off valve,
• wherein the cut-off valve retains a predetermined brake hydraulic pressure at the at least one wheel cylinder until a predetermined releasing condition is established even after the depression of the brake pedal is released when a vehicle is stopped, such that
• when the depression of the brake pedal is released, the control unit controls the cut-off valve so as to continue to retain the retained brake hydraulic pressure at the at least one wheel cylinder while gradually reducing the retained brake hydraulic pressure at a first reduction rate, and
• when the predetermined releasing condition is established, the retained brake hydraulic pressure is released such that
• the control unit controls the cut-off valve so as to gradually reduce the retained brake hydraulic pressure at the at least one wheel cylinder at a second reduction rate to thereby release the retained brake hydraulic pressure, wherein the second reduction rate is faster than the first reduction rate.