Tokico, Ltd.

Oki Electric Industry Co., Ltd.

Oki Electric Co., Ltd.

Hiromi Ando

Mitsuhiro Endo

Kunihiro Matsunaga

Toshio Takayama

Atsushi Fukasawa

Kiyoshi Tateoka

Kenji Sano

Satoru Suga

Takuro Sato

Takato Ogiwara

Atsuya Koshu

Yukou Ono

Shinichi Sato

Yukio Suzuki

Yoshihiro Hayashida

Naganori Koshimizu

Kenichiro Hosoda

Ryoichi Miyamoto

Yasuhiko Amari

Shinji Kawaguchi

Tomizo Azuma

Mitsuhiro Endou

Nobumaro Osaka

Kiyoshi Shirahata

Junichi Ikeda

Yukio Matsumoto

Yasuo Karasudani

Haruhiro Shiino

Tomonori Mouri

Tatsumasa Yoshida

Shuzo Watanabe

Yumi Takizawa

Yasuo Shoji

Yoshio Masuda

Tetsuro Nakajo

Eiichi Takano

Yoshihiko Kobayashi

A master cylinder of the invention supplies a brake fluid from a large diameter pressurizing chamber to a small diameter hydraulic chamber by opening a reverse flow checking opening and closing portion by sliding movement of a stepped piston forwardly, that is, fast fill and when the hydraulic pressure of the large diameter pressurizing chamber rises, a control valve escapes the hydraulic pressure of the large diameter pressurizing chamber to a reservoir to gradually lower in accordance with rise of the hydraulic pressure of the small diameter hydraulic chamber , thereby capable of reducing a strange feeling in a pedal feeling caused by sudden pressure release of the large diameter pressuring chamber

Master cylinder

There is disclosed a pneumatic booster having a vacuum chamber connected to an intake pipe of an engine. An air outlet of an ejector is connected to the intake pipe through a vacuum control valve, and an air inlet of the ejector is connected to an air cleaner. A vacuum pick-up port of the ejector is connected to the vacuum chamber of a booster body. The vacuum control valve comprises a control chamber and a control piston, and the negative pressure in the booster is introduced into the control chamber and acts on the control piston. When the negative pressure in the booster is insufficient, the control piston acts to open the control valve and a negative pressure is supplied from the ejector to the vacuum chamber. When the negative pressure in the booster is sufficiently high, the control piston acts to close the control valve and stops the operation of the ejector, thus reducing an effect of the ejector with respect to an air/fuel ratio of the engine.

Pneumatic booster and vacuum control valve used therefor

A master cylinder including a cylinder having one end open to the outside. A secondary piston guide ring, a sleeve and a primary piston guide ring are adapted to be fitted in this order into the cylinder from the one open end. A piston is slidably fitted in an axial direction of the cylinder, into each of the secondary piston guide ring, the sleeve and the primary piston guide ring. A retainer is provided at the open end of the cylinder, and adapted to abut against the primary piston guide ring so as to prevent escape of the primary piston guide ring from the cylinder. An elastic member is provided between a rearward end portion of the sleeve and a forward end portion of the primary piston guide ring.

A master cylinder includes a cylinder, a piston slidably provided in the cylinder, an annular cup seal held on an inner circumferential surface of the cylinder, and a relief port formed in the piston. The piston and the cylinder define a pressure chamber for generating fluid pressure in front of the piston, and the cylinder and an outer circumferential surface of the piston define a fluid supply chamber which communicates with a reservoir. The cup seal is adapted to slide against the outer circumferential surface of the piston to separate the fluid supply chamber from the pressure chamber. The relief port provides communication between the pressure chamber and the fluid supply chamber. A control taper surface is formed on the outer circumferential surface of the piston rearwardly from the relief port. The control taper surface is tapered toward the front of the piston and is capable of abutting against an inner circumferential surface of the cup seal.

A pneumatic booster includes a valve mechanism for introducing atmospheric air into a variable-pressure chamber in accordance with the movement of a plunger, propelling a power piston due to differential pressure generated between the variable-pressure chamber and a constant-pressure chamber and transmitting force by which the power piston is propelled through a valve body to an output shaft. The valve mechanism includes a poppet valve mechanism including a seal surface capable of abutting against an annular atmospheric valve seat formed in the plunger and a seal surface capable of abutting against an annular negative pressure valve seat formed on an inner surface of the valve body. The annular atmospheric valve seat of the plunger is located in a position forward in a direction of propelling of the power piston relative to the negative pressure valve seat and is substantially aligned with the negative pressure valve seat in an axial direction. The poppet valve mechanism has a main poppet valve including the seal surface capable of abutting against the negative pressure valve seat and a sub poppet valve including the seal surface capable of abutting against the atmospheric valve seat. The seal surface of the sub poppet valve is spaced apart in the axial direction from the seal surface of the main poppet valve.

Pneumatic booster

A dual function brake fluid control apparatus is presented for performing antiskid operation as well as another control operation involving control of the fluid pressure when the apparatus is not performing an antiskid operation. The apparatus is provided with a pressure relief valve having a valve body and a piston. The relief valve is forced closed by a biasing spring acting on a valve body, and when in the open state relieves the discharge pressure of a pump to the intake side of the pump. The piston closes the relief valve when the fluid pressure from the master cylinder exceeds a specific value. This configuration allows setting the discharge fluid pressure of the pump to apply fluid pressure to the wheel cylinders for non-antiskid control operations higher than that for the antiskid control operation. During an antiskid control operation, the fluid pressure relief valve also allows to maintain the discharge fluid pressure of the pump at the same value as or higher than the fluid pressure generated in the master cylinder.

Brake fluid pressure control apparatus

A brake booster includes a housing, a partition adapted to divide the interior of the housing into two chambers, and two diaphragms adapted to divide the two chambers into constant and variable pressure chambers. A control valve includes a valve body carried by the diaphragms, and a plunger slidably received in the valve body. The control valve is operatively connected to the variable pressure chambers to develop a pressure differential across the diaphragms to cause the diaphragms to move in response to actuation of an input rod. A reaction disk is disposed between an output rod and the valve body to transmit the reaction of movement of the output rod to the input rod. An adjusting mechanism is disposed between the plunger and the reaction disk and compressible so as to develop a greater degree of pressure differential when a force applied by the input rod exceeds a predetermined level. The reaction disk is caused to make contact with the contact disk and held out of contact with the spring and the plunger when the plunger is actuated.

Pressure differential operated brake booster

A tandem pneumatic booster having a shell body, the inside of which is divided into two, front and rear, chambers by a center shell. Each chamber includes a negative pressure chamber and a working pressure chamber. A valve body is slidably fitted in the shell body and the center shell with seal members therebetween. The valve body is provided with an air passage for communication between the front and rear working pressure chambers. A valve mechanism is actuated in association with an input shaft to introduce atmospheric air into the front and rear working pressure chambers through the air passage so as to apply thrust to front and rear power pistons. The diaphragm of the front power piston has a bead on an inner periphery thereof. The valve body has a groove on an outer periphery thereof. A portion of the air passage which leads to the front working pressure chamber has a main passage portion extending axially in the valve body, and a bypass extending radially outward from the main passage portion. A communicating port leading to the front working pressure chamber extends axially from the bypass. The bypass opens into the groove, and the radially outer end of the bypass is sealed with the bead.

A brake fluid pressure adjustment device is presented for controlling the wheel lock of a vehicle by controlling the flow of the brake fluid from the main fluid path to the bypass path by means of a pumping mechanism which is in constant operation. The pumping mechanism includes a suction valve which only allows a unidirectional flow of brake fluid from the pump, and a reservoir to the pump; an electromagnetic device which forces open the bypass path between the pump and the reservoir by attracting the bypass path control valve element in one direction; and a discharge valve which allows only the flow of brake fluid from the pump to the main fluid path. Therefore, by controlling the actions of the electromagnetic means, it is possible to control the decrease, holding and increase actions of the pressure adjustment device, without stopping and starting the pump. The device thereby provides a delicate and timely response to the brake pressure variation needs without being affected by the inertial effects of the pump.

Fluid pressure control device for antiskid brake system

A plunger moved with an input shaft is movably fitted in an axial bore of a valve body made of resin, and a valve mechanism selectively establishes and cuts off communication in a negative pressure passage and an atmosphere passage formed in the valve body according to the movement of the plunger. Also, a pair of radial holes formed to have a circular cross section are provided in the valve body by drilling work, and a plate type stop key formed in a fork shape having two claw branches is mounted by loosely inserting the branches in the radial holes. The stop key limits a movement range of the plunger. Also, a guide portion is formed on an outer circumference of the valve body to guide side surfaces of the stop key. The movement of the stop key is restricted by the guide portion and a step formed in the axial bore of the valve body. Therefore, a smooth operation of the pneumatic booster can be guaranteed.

The present invention provides a booster of the gaseous pressure type. The booster of the gaseous pressure type comprises: a power piston dividing the inside of a shell between a constant pressure chamber the inside of which is maintained in an approximately constant pressure, and a variable pressure chamber into which an operation gas can be introduced, wherein the power piston comprises a valve body projecting to the outside of the shell and a movable partition means for dividing the inside of the shell, with the inner periphery of the partition means fixed to the valve body; a valve for introducing the operation gas into the variable pressure chamber through a communication passage, according to a movement relative to the valve body of an input shaft which is connected to a brake pedal, and provided in the valve body; a cover for supporting the valve body and for forming an operation gas chamber which can store the operation gas, together with the shell, provided outside the portion of the valve body projecting from the shell; a gas source generating the operation gas; and a path for supplying the operation gas from the gas source to the operation gas chamber.

Booster of gaseous pressure type

A brake fluid pressure control apparatus includes a second pump communicating port disposed to face a first pump communicating port approximately perpendicularly to the direction of movement of a spool. The first and second pump communicating ports are connected to a master cylinder, and a check valve is provided between the master cylinder and the first and second pump communicating ports. The check valve is adapted to open when the master cylinder-side brake fluid pressure becomes a predetermined value higher than the pump discharge-side brake fluid pressure. A master cylinder communicating port is provided to extend along the direction of movement of the spool. A cut-off valve is provided between the master cylinder communicating port and the master cylinder. The cut-off valve is closed when the spool is moved to provide communication between the pump communicating ports and a wheel cylinder communicating port.

A pneumatic booster comprises a piston dividing a housing into front and rear chambers, the front chamber being is constant communication with a vacuum source, the rear chamber being selectively supplied with an atmospheric pressure source or a compressed air source, wherein a valve body of the piston includes a bore having a retainer mounted within, and an input rod movable within the retainer and having a compressed air passage extending therein, the bore of the valve body also having a first rear control valve and a second front control valve, such that movement of the input rod opens the first rear control valve to allow atmospheric air into the booster chamber and a further movement of the input rod opens the second front control valve to allow compressed air into the booster chamber, resulting in an increased output force of the booster.

Pneumatic booster having vacuum and pressurized air sources

The present invention relates to a brake fluid pressure control apparatus provided with a flow valve which, during the normal operation, when a spool is in the stationary position, a master cylinder communication port is communicated with a wheel cylinder communication port while the pump communication port is closed, and during an antiskid control operation, a pump communication port and a wheel cylinder communication port are communicated, as well as a switching device to switch between the first and the second conditions. In the first condition, a master cylinder communication port is communicated with the output fluid passage of the master cylinder while the communication between the pump communication port and the master cylinder communication port is shut off. In the second condition, the communication between the master cylinder communication port and the output fluid passage of the master cylinder is shut off while the pump communication port and the master cylinder communication port are communicated. Therefore, when two functions, antiskid and traction controls, are to be provided to a brake fluid pressure control apparatus having an antiskid control capability, there is no need to change the flow valve itself, in particular the spool, to provide the two functions.

Brake fluid pressure control apparatus for antiskid control and traction

The present invention presents an economical fluid pressure control device particularly applicable to controlling the fluid pressure in the wheels of an automobile provided with an antiskid capability so that the unpleasant pedal kickbacks are prevented under various operating conditions of the wheels. This is achieved by providing at least two wheel cylinders for one pressure generation source, a reservoir and a pump. A flow valve provided on each of the wheel cylinders is provided with a simple flow switching device which control the position of a spool, disposed inside the flow valve, which assumes a stationary position for non-antiskid operation mode and a operation position for antiskid operation mode. When one of the wheels is in the antiskid operation mode, and the other wheel is in non-antiskid operation mode, the brake fluid discharged from the pump is not allowed to enter the flow valve disposed in the non-antiskid operation mode. Therefore, the fluid pressure pulsations generated in the fluid circuit in the antiskid operation mode are not transmitted back to the pressure generation source through the flow valve in the non-antiskid operation mode. Therefore, there in no transmission of unpleasant pedal kickbacks at the pressure generation source.

Growing community of inventors

Tokyo, Japan

Hiromi Ando