| 摘要 |
PROBLEM TO BE SOLVED: To eliminate deterioration in brake operation feeling of a by-wire type brake device for a vehicle.SOLUTION: An input piston 14 and a master piston 20 are provided in a housing 16 so as to be mutually movable via a partition wall 17a and a first fluid chamber C1, and pressure regulation is applied to the master piston 20 by a second fluid chamber C2. The master piston 20 includes front and rear large-diameter and small-diameter pistons 21a and 21b which are fitted to each other in such a manner as to be mutually and longitudinally movable with a constant stroke L. When the large-diameter piston 21a advances by the pressure regulation to the second fluid chamber C2, the inflow of a brake fluid into the first fluid chamber C1 (a transition of the brake fluid) occurs on the basis of contraction of a fourth fluid chamber C4 via piping 30, only the large-diameter piston 21a moves at the initial stage of the shift of the brake fluid and impact pressure caused by the pressure regulation does not act on the small-diameter piston positioned in the first fluid chamber. This eliminates the risk of making operation feeling deteriorated by a change in the hydraulic pressure of the first fluid chamber C1, associated with a change in the capacity of the fourth fluid chamber due to the impact pressure and the movement of the master piston. |
