Aisin Seiki Kabushiki Kaisha

Toyota Jidosha Kabushiki Kaisha

Hirochika Shibata

Nobuyasu Nakanishi

Takumi Nishimura

Noboru Noguchi

Tadao Saito

Yoshiharu Adachi

Hiroshi Toda

Akira Shirai

Yoshihisa Nomura

Hiroaki Takeuchi

Masakazu Ishikawa

Masamoto Ando

Masashi Sawada

Tomohiko Hosoda

Toshiya Shibata

The present invention aims to provide a fluid pressure control apparatus which allows the gradient of pressure increase to be adjusted finely without using any accumulator. The fluid pressure control apparatus of the present invention includes a hydraulic pump driven by a drive motor and a wheel brake. A first orifice is provided in a passage portion on the side of an outlet of the hydraulic pump. Another passage portion on the side of an inlet of the hydraulic pump is connected to the passage portion between the first orifice and the hydraulic pump through a return passage. A switching valve and a second orifice are connected in series along the return passage. The pressure increase gradient can be set to a small value by changing the amount of fluid flowing into the wheel brake. This is effected, for example, by changing the ratio of the fluid passage area of the first orifice to that of the second orifice, the operational speed of the hydraulic pump, or the duty ratio of the switching valve.

Fluid pressure control apparatus for wheel brakes

An anti-skid apparatus for installation in a vehicle braking system having a master cylinder, a wheel brake cylinder and a primary fluid passage connecting these cylinders includes a changeover valve disposed in the primary fluid passage to selectively communicate the wheel brake cylinder with the master cylinder or with a reservoir, and a fluid pump for pumping a brake fluid from the reservoir and returning it to a portion of the primary fluid passage between the master cylinder and the changeover valve. The anti-skid apparatus further includes a control valve disposed in that portion of the primary fluid passage. The control valve comprises a piston slidably disposed in a housing, and a valve member slidably disposed in the piston and seatable on a valve seat with a cutout formed thereon. The control valve allows a flow of the brake fluid from the master cylinder and/or the fluid pump to the wheel brake cylinder through the changeover valve without restriction in normal braking operation. In the anti-skid operation, the control valve allows a restricted flow of the brake fluid through the cutout to reduce the increasing speed of the hydraulic pressure in the wheel brake cylinder.

Anti-skid apparatus for an automotive vehicle

A gas leakage detecting device for detecting leakage of a precharged gas from a gas-type accumulator which is connected to a hydraulic pump and which stores a pressurized hydraulic fluid delivered from the pump. The pump is turned on to initiate accumulation of the pressurized fluid in the accumulator when a pressure of the pressurized fluid falls below a lower limit, and turned off when the pressure rises to an upper limit. The detecting device detects an occurrence of leakage of the precharged gas from the accumulator, where a time duration between moments of activation and de-activation of the pump is less than a predetermined reference value.

Device for detecting leakage of precharged gas from gas-type accumulator

A hydraulic control device for an anti-skid brake system for a vehicle, including a solenoid-operated directional control valve for communication of a pressure chamber in a hydraulic actuator, selectively with a hydraulic power source and a reservoir, and a solenoid-operated flow control valve disposed between the directional control valve and one of the pressure chamber, hydraulic power source and reservoir, the hydraulic control device being operated to effect rapid and slow rise and fall of a pressure in the hydraulic actuator, in response to a slip ratio of a wheel of the vehicle. The flow control valve comprises a flow restrictor which permits a restricted flow of a fluid through the valve even when its valving member is seated on a valve seat in which a valve hole is open. The flow restrictor is provided in one of various forms except an ordinary orifice with a small diameter. The flow restrictor may be a groove formed in an end face of a valving member opposite to the valve seat, a rough or ragged surface of the valve seat or valving member, or a porous structure formed on the valving member so as to contact the valve seat. Alternatively, the flow restrictor may be formed by a porous structure which fills a hole formed in parallel with the valve hole which is open in the valve seat.

Solenoid-operated hydraulic control device for anti-skid brake system

A hydraulic anti-skid apparatus for installation in a vehicle braking system includes a cut-off valve disposed within a braking circuit connecting a master cylinder to a wheel brake cylinder, a piston arranged to be applied at opposite ends thereof with a braking pressure from the master cylinder and a hydraulic power pressure from a power pressure source and being associated with the cut-off valve to open the cut-off valve while the power pressure is applied thereto and to be displaced by the braking pressure when released from the power pressure to close the cut-off valve and subsequently to increase a capacity downstream of the cut-off valve, a first changeover valve arranged to normally apply the power pressure to the piston and to exhaust the power pressure when a road wheel tends to be locked, and a second changeover valve arranged to permit the power pressure applied to the piston through the first changeover valve when the master cylinder is operated and to exhaust the power pressure therethrough when the master cylinder is released from its operation. The second changeover valve is loaded to maintain the pressure acting on the piston at a low level while the master cylinder is inoperative.

Hydraulic anti-skid apparatus for automotive vehicles

An antiskid apparatus for an automotive vehicle having a master cylinder connected to wheel cylinders via respective brake lines, and a pressure regulating valve in a power hydraulic pressure line connecting an accumulator with a directional control valve, which is installed in a power hydraulic pressure line connecting the accumulator with a hydraulic pressure control piston. When the brake is applied, the pressure regulating valve is operable, in dependence upon master cylinder hydraulic pressure delivered by each wheel cylinder, to reduce power hydraulic pressure supplied by the accumulator to a hydraulic pressure higher, by a predetermined amount, than the master cylinder hydraulic pressure, and to deliver this reduced hydraulic pressure to each directional control valve. When the brake is not applied, the pressure regulating valve cuts off communication between the accumulator and each directional control valve and brings the hydraulic pressure in a hydraulic pressure line leading to a fluid chamber of the control piston to a value not higher than a set value through the directional control valve. Thus, the fluid chamber is supplied with hydraulic pressure reduced to a predetermined value to suppress a pressure change that occurs in the fluid chamber when the apparatus is operated, thereby reducing shock and noise and making it easier to control the operation of the apparatus.

Antiskid apparatus for vehicles

An actuator of an antiskid system for a vehicle and which includes a cut-off valve for selectively dividing a hydraulic pressure circuit connecting together a brake master cylinder and a wheel brake cylinder of the vehicle into a brake master cylinder-side hydraulic pressure circuit portion and a wheel brake cylinder-side hydraulic pressure circuit portion.

Actuator of antiskid system for vehicle

An actuator adapted to be used with the antiskid device of a vehicle and which includes cutoff valves which are capable of dividing each of the brake lines connecting the brake master cylinder of the vehicle to each brake cylinder at the wheels into two. The actuator further includes an electric motor and a high-pressure pump driven by the motor for forcing brake fluid into an accumulator. The brake fluid is also used as a mechanism for reducing braking effort when such are almost locked, i.e., for unlocking the wheels. The accumulator stores this unlocking fluid which is sufficiently pressurized to be greater than the maximum pressure that the brake fluid is under for braking action. Each piston taking the form of a right circular cylinder is advanced by the brake fluid and is withdrawn by the unlocking fluid supplied from the accumulator, so that the piston closes and opens the corresponding cutoff valve.

Growing community of inventors

Kariya, Japan

Hirochika Shibata