Aisin Seiki Kabushiki Kaisha

Toyota Jidosha Kabushiki Kaisha

Aisin Seiki K.k.

Genji Mizuno

Michiharu Nishii

Yoshihisa Nomura

Kenji Shirai

Masahiko Kato

Junichi Tanoue

Yoshihiko Tada

Kaoru Tsubouchi

Kenji Tozu

Kazutaka Kuwana

Satoshi Ishida

Tsuyoshi Yoshida

Masamoto Ando

Kaoru Nakamura

Shigeru Sakamoto

Chiaki Ochiai

Kyousuke Hata

Hideo Mizukoshi

Junichi Okuno

Ysohihiko Tada

A hydraulic braking system for an automotive vehicle having a power pressure source for generating a hydraulic power pressure, a master cylinder generating a hydraulic braking pressure in response to depression of a brake pedal, a dynamic hydraulic pressure generator for regulating the hydraulic power pressure in response to depression of the brake pedal and generating a regulated braking pressure, and a plurality of wheel brake cylinders for braking respective road wheels with one of the hydraulic braking pressure supplied from the master cylinder and the regulated braking pressure supplied from the dynamic hydraulic pressure generator. A power pressure changeover valve is provided and repeatedly changed over to be placed in one of a first operating position where a passage defining therein a closed space is communicated with a space under atmospheric pressure, and a second operating position where the passage is communicated with the power pressure source when the hydraulic power pressure exceeds a predetermined value, so that the hydraulic power pressure is reduced to a proper value.

Hydraulic braking system for an automotive vehicle having a pump and a

A hydraulic braking system includes the third piston slidably disposed between the first piston and the second piston of the tandem master cylinder so as to define the third pressure chamber between the third piston and second piston. The third pressure chamber is communicated with the dynamic hydraulic pressure generator. Thereby, due to supply the output hydraulic pressure of the dynamic hydraulic pressure generator to the third pressure chamber, the initial stroke of the brake pedal is reduced and the braking force is ensured as the ordinaly tandem master cylinder when the dynamic hydraulic pressure generator is not operated. Moreover, if the leakage of the brake fluid generates in the wheel cylinders, the flow of the brake fluid of the dynamic hydraulic pressure generator does not generate.

Tandem master cylinder with a third piston and chamber

A tandem master brake cylinder has first and second pistons, each piston associated with a fluid chamber and a pressure chamber. The pistons are displaced in response to actuation of a brake pedal. A hydraulic booster is coupled to a power source and is operable to enhance the piston movement and for conducting pressurized fluid to a second of the fluid chambers associated with a second piston to displace that piston in a manner reducing the volume of the pressure chamber associated with the first piston. In the event that a negative pressure is communicated with the second fluid chamber, e.g. by a loss of pressurized fluid from the power source, brake fluid is supplied through a one-way check valve to the second fluid chamber to prevent the negative pressure from reversing the motion of the second piston.

Hydraulic brake booster system with check valve in brake fluid reservoir

A hydraulic braking system includes a tandem master cylinder having a bore with an opening and a closed wall at opposite ends thereof which formed in a housing, a first piston slidably fitted in the bore so as to define a first pressure chamber and a first fluid chamber therein and operatively connected to a brake pedal, a second piston slidably fitted in the bore so as to define a second fluid chamber adjacent to the first pressure chamber and a second pressure chamber and operatively connected to the first piston. A normally open valve communicates with each piston so as to close passages formed in the each pistons and communication between each fluid chambers and each pressure chambers, respectively, when each piston is moved in response to the depression of the brake pedal. A power source generates a hydraulic power pressure. A dynamic hydraulic braking pressure generator generates the hydraulic power pressure supplied from the power source in response to depression of the brake pedal and outputs to the second fluid chamber. A plurality of wheel cylinders for braking respective road wheels are divided into a first group of wheel brake cylinders communicated with the first pressure chamber through one of dual hydraulic circuits and a second group of wheel brake cylinders communicate with the second pressure chamber through an another of the dual hydraulic circuits. A restrictor restricts the sliding distance of the second piston toward the first piston to at least a predetermined distance for closing the valve means. Due to such construction, the first stage idle stroke of the tandem master cylinder is shortened and the stroke of the brake pedal is shortened.

Hydraulic braking system

A hydraulic braking system for an automotive vehicle having a power source for generating a hydraulic power pressure, a reservoir, a master cylinder, a hydraulic booster for actuating the master cylinder in response to depression of a brake pedal and a plurality of wheel brake cylinders for braking respective road wheels, which are divided into a first group of wheel brake cylinders communicating with the master cylinder and a second group of wheel brake cylinders communicating with the hydraulic booster. An auxiliary cylinder is disposed between the hydraulic booster and the second group of wheel brake cylinders. The auxiliary cylinder includes a cylinder body having a cylinder bore defined therein and a piston axially slidably disposed within the cylinder bore. The piston forms within the cylinder bore a first chamber and a second chamber, and blocks a fluid communication therebetween. The first chamber communicates with the hydraulic booster and the second chamber communicates with the second group of wheel brake cylinders to which a braking force is applied in response to operation of the hydraulic booster. Thereby, the brake fluid filled in the hydraulic booster is prevented from flowing out, even if leakage of the brake fluid occurs in the second group of wheel brake cylinders.

Hydraulic braking system for an automotive vehicle

A hydraulic braking system capable of reducing the brake pedal stroke is provided by adding to the basic hydraulic braking system. The adding system is able to selectively execute the reduction of brake pedal stroke and, at the same time, capable of selectively adding anti-lock function and anti-slip function by including the changeover valves or opening and closing valves to the system. An auxiliary hydraulic pressure generator having a power hydraulic pressure source and regulator is interposed in the hydraulic conduit of at least one circuit, and an outlet port of the regulator is communicated to the wheel cylinders for connecting to the hydraulic conduit of the circuit. Brake pedal stroke can be reduced by inclusion of other conduit arrangements for adding the auxiliary hydraulic pressure generator and, at the same time, the changeover valve, anti-lock control changeover valve, and normally closed valve are selectively releasably added or mounted to the system, so that a brake system having short brake pedal stroke and sporty feeling can be obtained by low cost system ensuring desired braking operation. Additionally, anti-slip control for preventing the slipping of driving wheels can be added.

A hydraulic braking system for an automotive vehicle having a power source for generating a hydraulic power pressure, a reservoir, a master cylinder, a hydraulic booster for actuating the master cylinder in response to depression of a brake pedal and a plurality of wheel brake cylinders for braking respective road wheels, which are divided into a first group of wheel brake cylinders communicating with the master cylinder and a second group of wheel brake cylinders communicating with the hydraulic booster. An auxiliary cylinder is disposed between the master cylinder and the first group of wheel brake cylinders to which a hydraulic braking pressure from the master cylinder is directly applied in its inoperative condition, and it increases the hydraulic braking pressure in response to depression of the brake pedal in its operative condition which is made when the hydraulic power pressure, for example, is less than the hydraulic braking pressure by a predetermined difference. Control structure is connected to the auxiliary cylinder and allows the auxiliary cylinder in its operative condition when the hydraulic braking pressure, for example, is less than a predetermined value.

A hydraulic braking system for controlling the hydraulic pressure of the brake actuator and wheel cylinders includes a dynamic hydraulic pressure control system which transmits boosted hydraulic pressure in response to movement of a brake pedal. A master cylinder receives brake fluid pressure from a reservoir and transmits the fluid pressure from a pressure chamber in the master cylinder to a changeover valve. The changeover valve changes over the connection between wheel cylinders of the vehicle and the dynamic hydraulic pressure control system when the powered pressure which is transmitted from the dynamic hydraulic pressure control system is less than a predetermined pressure. A valve member of the changeover valve is movable between a first and second position so as to transmit the powered hydraulic fluid from the boost pressure chamber to the wheel cylinders of the rear wheels in a first position and block the transmission of the fluid in the second position.

The hydraulic brake system for a motor vehicle provides a brake fluid level detector which provides a signal to a control apparatus whereby the motor driven pump for providing braking pressure will be deactivated when the brake fluid level falls below a predetermined value. The system is also provided with pressure detector which detects the output fluid pressure and provides a signal to a control apparatus for stopping the anti-locking control apparatus of the brake system if the pressure falls below a predetermined value.

Hydraulic brake system for vehicles

A pair of spaced apart large-diameter and small-diameter lands between which a fluid chamber is defined are formed on a second piston in a tandem cylinder to which an anti-skid device is added. Booster pressure is applied to the fluid chamber to act on the large-diameter land in a manner fluidly locking the second piston against movement despite a reduction in pressure in the first and second pressure chambers during operation of the anti-skid device. As a result, the movement of the brake pedal in the normal direction of depression is prevented when the anti-skid devices operates.

A hydraulic brake system includes a master cylinder for generating a brake fluid pressure in response to a brake pedal, a power fluid source for generating a power fluid pressure by increasing a brake fluid to a predetermined pressure. A dynamic fluid pressure control apparatus supplies the brake fluid pressure to regulate the power fluid pressure from the power fluid pressure source in response to the brake pedal. A plurality of wheel cylinders of each wheel for the vehicle are fluidically communicated with a dynamic fluid pressure control apparatus and the master cylinder via a fluid passage separated into plural control systems. A first changeover valve fluidically and selectively communicates at least one system of the wheel cylinder with one of the dynamic fluid pressure control apparatus and the master cylinder and a control valve disposed in a fluid passage communicates the first changeover valve and the wheel cylinder controls the brake fluid pressure supplied to the wheel cylinder by opening and closing the fluid passage in accordance with the slip state of the wheel upon braking. A control circuit controls the actuation of the control valve and the first changeover valve, and a second changeover valve is disposed in a fluid passage fluidically communicating the first changeover valve and the dynamic fluid pressure control apparatus and selectively communicates the fluid passage with one of the dynamic fluid pressure control apparatus and the power fluid pressure source.

Hydraulic brake system

A relief valve used for hydraulic devices such as the master cylinder for motor vehicles, comprising a housing for passing hydraulic fluid therethrough to adjust the hydraulic pressure, a ball valve disposed in the housing, a coil spring for pushing the ball valve in the housing and plural finger-like portions formed in the inside of the housing to resiliently nip the ball valve so as to prevent the vibration of ball valve in the direction of diameter of the housing at the time of releasing hydraulic fluid through the inside of the housing, thereby making it possible to avoid the generation of strange noise by the vibration of ball valve. It is desirable to form the surface of valve body or the valve body side surface of the finger-like portions so that it has a surface roughness within a specific range in order to make the noise prevention effect more perfect.

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Toyoake, Japan

Genji Mizuno