Patent ID: 11958464
Assignee: HITACHI ASTEMO, LTD.
Field: Transport (Mechanical engineering)
Classification: CPC B | IPC B

Claim 10:
11. A brake system comprising:
a stroke simulator; and
a hydraulic pressure unit,
the stroke simulator including
a first chamber connected to a master cylinder, and
a second chamber separated from the first chamber by a piston,
the hydraulic pressure unit including
a connection fluid passage that connects the master cylinder and a braking force application portion to each other, the braking force application portion being configured to apply a braking force to a wheel portion (FL to RR) according to a brake hydraulic pressure,
a shut-off valve provided in the connection fluid passage,
a hydraulic pressure source configured to supply brake fluid to a fluid passage of the connection fluid passage that is located between the shut-off valve and the braking force application portion,
a pressure sensor configured to detect a hydraulic pressure in the master cylinder, and
a control unit, the control unit including:
a stroke-wheel cylinder hydraulic pressure characteristic setting portion configured to set a stroke-target wheel cylinder hydraulic pressure characteristic with respect to the pedal stroke;
a stroke-target wheel cylinder hydraulic pressure calculation portion configured to calculate a first pressure value Pstr by referring to the stroke-target wheel cylinder hydraulic pressure characteristic with respect to the pedal stroke set by the stroke-wheel cylinder hydraulic pressure characteristic setting portion based on the pedal stroke detected by the stroke sensor;
a master cylinder hydraulic pressure-wheel cylinder hydraulic pressure characteristic setting portion configured to set a master cylinder hydraulic pressure-target wheel cylinder hydraulic pressure characteristic with respect to the master cylinder hydraulic pressure; and
a master cylinder hydraulic pressure-target wheel cylinder hydraulic pressure calculation portion configured to calculate a second pressure value Ppmc by referring to the master cylinder hydraulic pressure-target wheel cylinder hydraulic pressure characteristic with respect to the master cylinder hydraulic pressure set by the master cylinder hydraulic pressure-wheel cylinder hydraulic pressure characteristic setting portion based on the master cylinder hydraulic pressure detected by the master cylinder hydraulic pressure sensor,
the control unit being configured to:
acquire a piston stroke position of the piston,
determine brake hydraulic pressure to generate in the braking force application portion based on the first pressure value in a case where the acquired piston stroke position is smaller than a preset predetermined position, and
determine brake hydraulic pressure to generate in the braking force application portion based on the first pressure value and the second pressure value in a case where the acquired piston stroke position is equal to or greater than the preset predetermined position.