Vehicle brake device

摘要

When brake fluid of a first wheel cylinder (39a) of a slave cylinder (23) is increased by supplying the brake fluid to a first wheel cylinder (16, 17) by a first pump (64A), a second piston (38B), which is a free piston, of the slave cylinder (23) moves toward the first fluid pressure chamber (39A) side, the volume of a second fluid pressure chamber (39B) thereby expands, and the brake fluid pressure of a second wheel cylinder (20, 21) can be reduced, whereas when brake fluid pressure of the second fluid pressure chamber (39B) is increased by supplying the brake fluid to the second wheel cylinder (20, 21) by a second pump (64B), the second piston (38B) moves toward the second fluid pressure chamber (39B) side, the volume of the first fluid pressure chamber (39A) thereby expands, and the brake fluid pressure of the first wheel cylinder (16, 17) can be reduced, thus enabling a difference in brake fluid pressure to be freely generated between the first and second wheel cylinders (16, 17).

主权项

1. A vehicle brake device in which a first piston that is operated directly by a drive source and a second piston that is a free piston operated indirectly in response to operation of the first piston are disposed in tandem within a cylinder main body, a first fluid pressure chamber formed between the first piston and the second piston is connected to first wheel cylinders of front-side left and right wheels or rear-side left and right wheels, and a second fluid pressure chamber formed between the second piston and the cylinder main body is connected to second wheel cylinders of left and right wheels on a side different from the first wheel cylinders,
wherein the vehicle brake device comprises: a first pump supplying brake fluid of the first fluid pressure chamber to the first wheel cylinders; and a second pump supplying brake fluid of the second fluid pressure chamber to the second wheel cylinders; a first electromagnetic valve controlling the state of communication between a suction side of the first pump and the first fluid pressure chamber; a second electromagnetic valve controlling the state of communication between a discharge side of the first pump and the first fluid pressure chamber; a third electromagnetic valve controlling the state of communication between a suction side of the second pump and the second fluid pressure chamber; and a fourth electromagnetic valve controlling the state of communication between a discharge side of the second pump and the second fluid pressure chamber, wherein the second electromagnetic valve and the fourth electromagnetic valve have a variable degree of opening.