Hitachi Automotive Systems, Ltd.

Hitachi, Ltd.

Masaru Sakuma

Toshio Takayama

Takuya Usui

Kazumoto Sano

Toshiyuki Ajima

Kentaro Ueno

Norikazu Matsuzaki

Hideaki Ishii

Kunihiro Matsunaga

An electric booster including a plunger movable by operation of a brake pedal, an electric motor controlled based on a relative displacement between the plunger and the linear motion member, which is detected by a relative displacement sensor, and a ball and screw mechanism. The linear motion member pushes a piston of a master cylinder through a reaction member, thereby generating a brake force. Part of a reaction force from the master cylinder is fed back to the brake pedal through the reaction member. When a reference position sensor detects that a relative position of the plunger to the linear motion member coincides with a predetermined reference position, a detection value of the relative displacement sensor is stored as a relative displacement reference value, and relative displacement between the plunger and the linear motion member is determined.

Booster

A brake apparatus, which is configured to generate a hydraulic pressure in a master cylinder, sets a control position of a primary piston. According to a movement of an input piston in response to an operation of a brake pedal, the brake apparatus generates a hydraulic pressure in a primary chamber of the master cylinder by driving the primary piston by an electric motor to supply brake fluid to a brake caliper, thereby exerting a brake effect. The brake apparatus sets a first control position where the primary chamber is out of communication with a reservoir, and a second control position where the primary chamber is in communication with the reservoir as a holding position of the primary piston when no brake is applied. Then, the brake apparatus appropriately switches the holding position of the piston between the first control position and the second control position.

Brake apparatus

A motor drive device inputs two detection signals from a rotation position sensor thereby to detect a rotation position, and controls a voltage to be applied to a motor according to the detected rotation position. The motor drive device has a control unit for outputting a first voltage in a first state in which the square sum of sampling values sampled from the two detection signals is a predetermined value, and outputting a second voltage in a second state in which the square sum is not the predetermined value.

Motor drive device

In response to depression of a brake pedal (), an electric brake () mounted on the rear side starts to generate a braking force at the time of stroke hbefore a fluid pressure brake () mounted on the front side starts to generate a braking force when the stroke reaches stroke h. Accordingly, the rear side is able to generate a braking force prior to the front side, whereby it is possible to reduce a rigid feeling, and therefore improve the pedal feeling.

Brake device

Provided is a brake system capable of preventing fuel efficiency of a vehicle from being lowered. After a brake pedal is released, a pump is driven under a state in which opening/closure of valves included in an ABS/VDC actuator are regulated so that pressure-reduction control for returning a brake fluid in wheel cylinders to a master cylinder is performed. Therefore, the brake fluid remaining in the wheel cylinders is returned to the master cylinder via the pump to increase a hydraulic pressure of the master cylinder. As a result, return characteristics of an electric actuation unit are improved. Therefore, for example, even if viscosity of grease applied onto a rotary-to-linear motion converting mechanism is increased at a low temperature or the like, pistons of the master cylinder can be appropriately returned to initial positions.

Brake system

In a brake system, when setting a control origin position for a resolver for detecting a moved position of a booster piston, communication between a master cylinder and wheel cylinders is interrupted by cut valves. Thereafter, the booster piston is moved forward by an electric actuator in a direction in which a hydraulic pressure is generated so that a position detected by the resolver upon detection of generation of the hydraulic pressure by a hydraulic pressure sensor (position at a time of generation of hydraulic pressure) is obtained. A position obtained by moving backward the position at the time of generation of hydraulic pressure by a predetermined amount is set as the control origin position.

The present invention provides an electric disk brake which enables an operation for wiring the harness to be easily conducted without the risk of lowering production efficiency. A caliper body-side connectorwhich, together with a harness-side connectorof a harness, forms a connector, is provided in a caliper body. In the caliper body-side connector, first to fourth lead-out terminalstoconnected to an electric portion for an electric motor are arranged in this order from a first side portiontowards a third side portionof a cover. In the harness-side connector, a first set of first to fourth harness-side terminals and a second set of first to fourth harness-side terminals independently connected to the first to fourth lead-out terminalstoare arranged in reverse order. When an electric disk brakeis used for each of the left rear wheel and the right rear wheel, one of the first set of first to fourth harness-side terminals and the second set of first to fourth harness-side terminals is used for the left rear wheel while the other is used for the right rear wheel, and the first to fourth lead-out terminals and the first to fourth harness-side terminals are connected. The harnessesextend in the same direction relative to the vehicle, thus ensuring ease of operation for wiring the harnesses

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Kai, Japan

Masaru Sakuma