Toyota Jidosha Kabushiki Kaisha

Aisin Seiki Kabushiki Kaisha

Nippondenso Co., Ltd.

Toyota Jidosha Kogyo Kabushiki Kaisha

Aisan Kogyo Kabushiki Kaisha

Jidosha Kabushiki Kaisha

Toyota Jidosha Kabushiki Kaisha & Nippondenso Co., Ltd.

Yoshihisa Nomura

Michiharu Nishii

Masahiko Kato

Hiromi Otsuki

Akira Shirai

Yoshiyuki Hattori

Nobuyasu Nakanishi

Kenji Shirai

Kazumasa Nakamura

Hiroyuki Oka

Genji Mizuno

Kaoru Ohashi

Takahiro Nogami

Junichi Tanoue

Ryoichi Matsuura

Hiroshi Kawaguchi

Hiroshi Fujinami

Shinichi Hori

Kazuma Matsui

Akira Kuno

Naohiko Tsuru

Masakazu Ishikawa

Takaaki Ohta

Yoshihiko Tada

Ikuya Kobayashi

Yoshiaki Inoue

Hiroaki Takeuchi

Masayoshi Katagiri

Noboru Noguchi

Hiroyuki Kondo

Koichi Suda

Kiyotaka Ise

Yuichi Imani

Kiyoshi Nishiwaki

Fujio Toba

Toshihiro Takei

Yuzo Imoto

Takafumi Inagaki

Yoshiaki Hoashi

Hideaki Suzuki

Tomoyuki Nogami

Masamoto Ando

Nobuyoshi Onogi

Mamoru Shimamoto

Shin Koike

Hideo Wakata

Toshiharu Naito

Shigeru Sakamoto

Hiroji Kinbara

Shuho Nishina

Hirochika Shibata

Takahiro Goshima

Hiroshi Takeshita

Masakazu Tago

Shigemi Sakakibara

Tadashi Kozawa

Masakazu Sugisawa

Susumu Masutomi

Kenichi Numata

Yoshinori Mori

Harumasa Minegishi

Shingo Watanabe

Kozi Takagi

Eiji Miura

Hidenobu Kazita

Sadayuki Ohno

Norihiko Okochi

Shoichi Yamamoto

Noriyuki Ido

Yuuichi Imani

Ysohihiko Tada

Yoshikane Yoshimura

A control apparatus in a brake system of a motor vehicle having a wheel brake cylinder for braking a vehicle drive wheel, the apparatus including a pump for pressurizing a fluid received from a low-pressure source, a valve device having a pressure increase state for permitting the fluid pressurized by the pump to be fed into the wheel brake cylinder, and a pressure decrease state for permitting the fluid to be discharged from the wheel brake cylinder into the low-pressure source, a traction control device for selectively placing the valve device in at least the pressure increase and decrease states, to control the pressure of the fluid in the wheel brake cylinder for thereby controlling the drive force of the drive wheel so as to control the amount of slip of the drive wheel, and a pump delivery saving device for reducing the delivery pressure of the pump in at least a portion of a time period during which the valve device is placed in a state other than the pressure increase state.

Brake control apparatus capable of traction control of vehicle drive

A hydraulic brake system operates so that under anti-lock control, the braking forces for the rear wheels are enhanced in order to reduce braking loads for the front wheels. Further, upon the occurrence of a malfunction of the anti-locking control, the hydraulic pressure which is supplied to the front and the rear wheels is equalized in order to prevent the rear wheels from locking. In preferred embodiments, a small hydraulic pressure is supplied from a master cylinder to the front wheels while a large pressure is supplied from a brake booster to the rear wheels. Due to the large fluid pressure, the braking forces of the rear wheels are enhanced so that the rear wheels might tend to lock easily. However, anti-lock control can be performed effectively in order to avoid the rear wheels from locking. Upon the malfunction of the anti-lock control, a switching valve is operated so that the brake pressure which is supplied to the front and the rear wheels is equalized. The switching valve operates so that the braking forces of the rear wheels are mutually reduced in comparison to the braking forces of the front wheels. Therefore, it is also possible to prevent the rear wheels from locking if the anti-lock control fails. Thus, the vehicle stability is maintained even if the anti-lock control fails.

Hydraulic brake system with enhanced braking force for rear wheels

A fluid leakage preventing device incorporated in a hydraulically-operated system which includes an accumulator for storing a working fluid under pressure, an actuator operated by the fluid supplied from the accumulator, and a control valve having an open position and a closed position for fluid communication and disconnection between the accumulator and the actuator, respectively. The fluid leakage preventing device includes a fluid leakage detector for generating an output signal indicative of the leakage flow of the fluid from said accumulator through the control valve placed in the closed position. The device further includes a valve reciprocating arrangement responsive to the output signal of said fluid leakage detector, for effecting at least one reciprocating movement of a valving member of the control valve.

Device for detecting and eliminating accumulator fluid leakage through

A hydraulic power booster having a lever device disposed in operative association with a reaction piston, a power piston and a valve spool, for moving the valve spool in one of opposite axial directions thereof for applying a pressure of a pressure source into a power chamber to advance the power piston, in response to a relative movement between the reaction and power pistons. The booster is provided with a backup actuator including a cylinder, and a valve drive piston which slidably engages the cylinder. The cylinder and the valve drive piston cooperate with each other to define a first fluid chamber communicating with the power chamber, and a second fluid chamber communicating with a pressure chamber in which a pressure is generated according to an advancing force of the power piston. The valve drive piston moves the valve spool in the above-indicated one axial direction, in engagement with the valve spool, when the valve drive piston is moved in a direction from the second fluid chamber toward the first fluid chamber.

Hydraulic power booster including backup actuator in addition to lever

A hydraulic braking system for an automotive vehicle is provided with a power source for generating a hydraulic power pressure, a master cylinder, a hydraulic booster for introducing the hydraulic power pressure and actuating the master cylinder in response to operation of a brake operating member, a wheel brake cylinder for braking a road wheel, a changeover valve, and anti-skid control device for actuating the changeover valve into a position where the wheel brake cylinder is communicated with the booster and regulating the hydraulic pressure in the wheel brake cylinder on the basis of the hydraulic power pressure in the booster when the road wheel is in a slip condition. The hydraulic braking system includes a failure detecting feature for producing a power pressure failure signal when the hydraulic power pressure in the booster is lower than the master cylinder pressure by at least a predetermined value, an anti-skid prohibiting device for prohibiting the anti-skid control operation in accordance with the failure signal, and a detection preventing feature for preventing the failure detecting features from producing the failure signal when the hydraulic power pressure in the booster exceeds a predetermined pressure which is lower than a limit pressure for boosting operation of the booster.

Hydraulic braking system for an automotive vehicle

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.

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 having an auxiliary piston disposed between an input piston and a presser piston, so as to define a first power chamber between the auxiliary and presser pistons, and a second power chamber between the input and auxiliary pistons. The presser piston cooperates with a housing to define a pressure chamber connected to a first braking arrangement. The first power chamber is connected to a second braking arrangement and supplied with a power pressure from an external hydraulic source through a control valve and the second power chamber. The system includes a connecting mechanism connecting the auxiliary and presser pistons such that the two pistons are normally placed in a spaced-apart state but are abuttable on each other. The system also includes a valve device disposed in a passage formed through the auxiliary piston, so as to inhibit a fluid flow from the first power chamber to the second power chamber when the input and auxiliary pistons are advanced as a unit in abutting relation with each other, and permit fluid flows in both directions between the two power chambers when these pistons are placed in other conditions. The system is capable of activating the first and second braking arrangements by an operating force acting on the input piston through a manually operated mechanism, in the event of a power failure in the second power chamber or external hydraulic source.

Tandem master cylinder with valved hydraulic power booster fluid passage

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 tandem master cylinder with a booster used for a hydraulic actuator such as an automotive brake system. The master cylinder has a first and a second independently movable presser piston disposed in tandem in a first housing such that the presser pistons and the first housing define a first and a second pressure chamber. The booster has a first power piston advanced by a fluid pressure in a first power chamber formed in a second housing, to advance the first presser piston. The booster has a valve operable due to a relative movement between the first power piston, and an operating member for operating said booster, whereby the fluid pressure in the first power chamber is controlled according to an operating force applied to the operating member. In a third housing, there is disposed a second power piston, which has opposite pressure-receiving faces one of which receives a fluid pressure in the second pressure chamber, the other face receiving a fluid pressure in a second power chamber, whereby the fluid pressure in the second pressure chamber is controlled according to the fluid pressure in the second power chamber. The second power chamber is connected to the first power chamber.

Tandem master cylinder with booster piston at pedal-remote end of master

A braking control apparatus for use in a motor vehicle having at least one wheel comprising a master cylinder for generating a hydraulic pressure in response to a braking operation of a vehicle driver, an accumulator for accumulating a hydraulic pressure and at least one wheel braking cylinder for braking the wheel in accordance with a hydraulic pressure supplied thereinto. A passage system is provided so that the wheel braking cylinder is communicated therethrough with the master cylinder and the accumulator. In the passage system are provided first and second change-over valves for cutting off the pressure from the master cylinder, cutting off the pressure from the accumulator and a third control valve disposed between the wheel braking cylinder and the master cylinder or the accumulator for establishing and cutting off the communication therebetween. An control unit controls the operations of the first to third valves so as to, in response to cutting off the communication with the accumulator, establish the communication with the wheel braking cylinder, and then establish the communication with the master cylinder. This valve control prevents the high-pressure remaining in the passage system after the cutting-off of the communication with the accumulator from being rapidly applied to the master cylinder.

Braking control apparatus for use in motor vehicle

A vehicle anti-lock braking system having a master cylinder operated upon operation of a brake operating member, a wheel cylinder activated by a pressure produced by the master cylinder, and an anti-lock control device which includes a slip ratio detector for detecting a slip ratio of a drive wheel of the vehicle, and a pressure regulating device for controlling a pressure in the wheel cylinder, so as to maintain the slip ratio in an optimum range. The system also has a traction control device including a traction control power source, and a communication switching device for selective communication of the pressure regulating device with the traction control power source or the master cylinder. The switching device maintains a discharge port of the pressure regulating device in communication with a reservoir while the traction control power source is in communication with the pressure regulating device, and disconnects the discharge port from the reservoir while the master cylinder is in communication with the pressure regulating device.

Anti-lock braking system for a vehicle having a traction control module

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

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Toyota, Japan

Yoshihisa Nomura