Aisin Seiki Kabushiki Kaisha

Advics Co., Ltd.

Toyota Jidosha Kabushiki Kaisha

Toyota Jidosha Kogyo Kabushiki Kaisha

Aisin Seiki Company, Ltd.

Kaoru Tsubouchi

Akihiko Miwa

Nobuyuki Hirota

Katsuhiro Mita

Michiharu Nishii

Koji Suzuki

Yoji Inoue

Tomoyasu Sakai

Toshihiro Nakano

Chiaki Ochiai

Akimoto Okada

Yoichi Terasaki

Koichi Hashida

Hiroshi Uemura

Juichi Shibatani

Kaoru Nakamura

Hideaki Iijima

Youichi Furuta

Yohichi Furuta

Minoru Watanabe

Akira Funahashi

Yoko Takatori

Kenji Shirai

Tomoyuki Nogami

Hiroaki Aizawa

Haruo Arakawa

Atsushi Ohmi

Atsushi Yasuda

Genji Mizuno

Shigeru Sakamoto

Yuzuru Sugiura

Takeo Yamazaki

Kenichi Kobayashi

Tomio Tachino

Shinji Sakata

Takuya Inaba

Yoichi Furuta

Takashi Kiriyama

Shozaburo Tsuchida

Takeo Murata

Yoshihiro Nakagiri

Kaoru Nanamura

Toshiharu Okuda

A motor-driven parking brake apparatus includes a load sensor (pressure sensor) for detecting axial load of a screw shaft. The pressure sensor includes a transmission member which receives the axial load via a circular surface of a plate, and a casing which accommodates the transmission member and receives the axial load via the transmission member. This casing has a circular opening having an opening area smaller than the surface of the circular surface. The pressure sensor detects a pressure generated due to a load received from an exposed portion of the transmission member which is exposed from the circular opening. Due to characteristics of the transmission member, the load received from the exposed portion is a portion of the axial load and proportional to the axial load.

Motor-driven parking brake apparatus

In a vacuum type brake booster, the reaction of output transmitted from an output shaft to a reaction member is transmitted to a valve body, a plunger, and a stepped pin. A valve mechanism, which is assembled to an axial hole of the valve body, includes an atmospheric valve seat which advances and retreats together with the plunger, a vacuum valve seat assembled to the valve body to advance and retreat, and a valve member having an atmospheric valve portion which forms an atmospheric valve in cooperation with the atmospheric valve seat and a vacuum valve portion which forms a vacuum valve in cooperation with the vacuum valve seat. The stepped pin is pushed rearward when a corresponding portion of the rear surface of the reaction member deforms and bulges rearward, and pushes the vacuum valve seat rearward in relation to the valve body.

Vacuum type brake booster

A master cylinder includes a piston received in a cylinder body and formed with piston ports. An annular groove is formed in the inner periphery of the piston in its area where the piston ports are formed. An arcuate plate is received in the annular groove. A sleeve is inserted into the arcuate groove to retain the arcuate plate in the annular groove. A gap as a fluid passage is defined between the arcuate plate and the inner surface of the annular groove. A pressure chamber defined in the cylinder body communicates with a communication passage communicating with a reservoir through the above gap, cutouts of holes formed in the arcuate plate and holes formed in the sleeve. When hydraulic fluid flows rapidly from the pressure chamber toward the reservoir, the arcuate plate is adapted to elastically and radially expand, thus closing some of the piston ports.

Plunger type master cylinder

In a negative pressure type booster device, secondary passagescommunicating directly with the atmosphere is formed between the internal surface of a sliding cylindrical portionof a valve pistonand the external surface of a silencer, and communication meansis provided for being controlled to vary its path area in dependence on the advance amount of an input rodwhen the same is moved beyond a predetermined distance relative to the valve piston. Thus, when a brake pedalis stepped on strongly, the atmospheric air can be led from the secondary passagesthrough the communication meansto a variable pressure chamber, so that the property of the responsiveness in braking operation can be improved to a responsiveness enhancing property which varies in dependence on the manner of stepping the brake pedal

Negative pressure type booster device

A master cylinder includes a cylinder body, primary cups supported on the inner periphery of the cylinder body, and a primary piston and a secondary piston inserted in the cylinder body so as to be in sliding contact with the respective primary cups. The cylinder body is integrally formed with annular walls behind the respective primary cups. The annular walls have a greater inner diameter than the inner diameter of the cylinder body to define annular passages between the annular walls and the respective pistons. Connecting passages having a greater radial dimension than the annular passage are defined between the inner periphery of the cylinder body and the respective pistons behind the respective annular walls so as to communicate with a reservoir. While the master cylinder is not actuated, piston ports formed in the respective pistons communicate with the reservoir through the respective annular passages and connecting passages. Brake fluid can thus be sucked smoothly into the respective pressure chambers both during a return stroke of the pistons and during automatic brake control such as vehicle stability control.

Master cylinder

A vacuum booster which moderates a retraction speed of a valve seat member to restrain a contact noise between a key member retracting in a unitary manner with the valve seat member and a flange surface of a plunger. The vacuum booster includes a noise restriction device.

Vacuum booster

Reaction force from a reaction member is divided and transmitted to a front shaft portion of a plunger via abutment member and to a flange portion of the plunger via a spring unit. The spring unit includes a tubular first holding member assembled to the front shaft portion of the plunger and being engageable, at its front end portion, with the reaction member, a second holding ember assembled to a rear end portion of the first holding member and having a rear end portion which extends rearward from the first holding member for engagement with the flange portion, and Belleville springs held between the first and second holding members. When the reaction force transmitted from the reaction member to the first holding member exceeds the load of the springs, the first holding member moves while compressing the springs and engages with a stepped portion of a valve body.

Vacuum-operated booster

A master cylinder includes a primary cup received in a groove formed in the inner wall of the cylinder body. Projections are formed on a radially inner portion of the cup so as to protrude forwardly from the front end of the radially inner portion. The projections are adapted to be pressed against the front end wall of the cup-receiving groove and elastically deformed under a pressure difference produced between the front and rear ends of the cup when the piston is returned quickly, allowing the cup to advance in the cup-receiving groove. When the cup advances in the groove, a fluid passage is defined between a base portion of the cup and the rear end wall of the groove. Brake fluid from the reservoir flows through this fluid passage, through a gap formed between a radially outer portion of the cup and the radially outer wall of the groove when the radially outer portion of the cup is deformed by the fluid flow, and through a fluid passage defined between the cup and the front end wall of the groove by the projections.

A negative pressure type booster device possesses a valve mechanism constructed to compensate for insufficient depressing force applied to a brake pedal upon emergency braking. Upon depression of the brake pedal, first negative pressure valves contact first negative pressure valve seats to block a variable pressure chamber from communication with a constant pressure chamber, and an atmosphere valve seat is separated from an atmosphere valve to communicate the variable pressure chamber with atmosphere. A partition member thus moves forwards depending on the pressure difference between the chambers to output a propelling force from an output rod. When the brake pedal is stepped on quickly, a valve member is urged backwards by a spring member causing second negative pressure valve seats to contact second negative pressure valves and move the valve member backwards. The atmosphere valve separates from the atmosphere valve seat, and the variable pressure chamber quickly communicates with atmosphere.

A negative pressure type booster includes a power piston, a slide valve, and a holding mechanism, among others, and assists a driver during emergency braking. The holding mechanism is adapted to hold the slide valve at a predetermined frontward position, and includes a latch member that is mounted to the power piston in such a manner as to be linearly movable in a radial direction, and a garter spring for biasing the latch member radially inward. The latch member has a hook that can be engaged with and disengaged from a hook provided on the slide valve. When a plunger moves frontward relative to the power piston by a quantity greater than a predetermined value, a push slope provided on the plunger pushes a passive slope provided on the latch member radially outward, whereby the hook of the latch member is disengaged from the hook of the slide valve.

Negative pressure type booster

A master cylinder includes a cylinder body and primary and secondary pistons slidably received in the cylinder body, thereby defining first and second pressure chambers in the cylinder body. The first and second pressure chambers communicate with a reservoir through first and second fluid passages, respectively. During automatic brake control such as traction control or vehicle stability control, hydraulic fluid is drawn from the reservoir through the first and second pressure chambers. A throttle valve is received in each of the first and second fluid passages. The throttle valves are adapted to open while the master cylinder is inoperative and to close under backflow pressure when hydraulic fluid flows from the pressure chambers toward the reservoir. The throttle valves each include a floating valve body and a valve seat. The valve seat has its radially outer portion liquid-tightly joined and fixed to the cylinder body so that the fixed position of the valve seat and the lowermost position of the floating valve body are determined by the cylinder body.

In a negative pressure type booster, an atmospheric valve seat is formed on an annular disk of an input member, which disk extends radially outward. The annular disk and an annular diaphragm located frontward of the annular disk and mounted to the input member define an annular atmospheric chamber. The atmospheric chamber communicates with the atmosphere via an air hole formed in the annular disk. The diaphragm is supported from the front by a power piston. The diaphragm is a flexible member. Inner and outer circumferential portions of the flexible member are formed into respective rolling portions for allowing frontward/rearward movement of the input member by means of curviform deformation. An atmospheric control valve portion, which is seated on and separated from the atmospheric valve seat, and a vacuum control valve portion, which is seated on and separated from a vacuum valve seat formed on the power piston, are axially separated.

A master cylinder includes a primary piston and a secondary piston, each formed with piston ports which include two different kinds of ports, i.e. first ports for ensuring communication between a reservoir and a pressure chamber of the master cylinder, and second ports through which brake fluid is sucked from the reservoir during automatic break control. The second ports are greater in number than the first ports and are positioned forwardly of the first ports so that the second ports are closed by primary cups which are provided on the inner wall of the cylinder body so as to be in sliding contact with the respective pistons before the first ports when the respective pistons are advanced. An annular wall having a greater inner diameter than the outer diameter of the pistons is formed on the inner wall of the cylinder body to support the back of each of the primary cups. An annular groove is formed in each piston so as to communicate with the first ports. The annular groove is preferably arranged so as to radially oppose the annular wall when the piston is in an inoperative position.

A brake master cylinder includes a cylinder body having a circumferential groove formed therein. A primary cup is received in the groove and supported axially by a rear wall defined by the groove. A primary piston is inserted in the cylinder body in sliding contact with the primary cup. The rear wall has a radially inner surface formed with a plurality of grooves. A passage leading to a reservoir is provided in the rear of the grooves. The piston is formed with radial through holes corresponding to the grooves. When the piston is at the return end of its stroke, the pressure chamber defined in the cylinder body can communicate with the reservoir through the radial through holes, the grooves and the passage.

A master cylinder includes a cylinder body and a piston slidably inserted in the cylinder while kept in slide contact with two cup members both fitted in the inner surface of the cylinder body to seal the gap between the piston and the inner surface of the cylinder body. On its radially inner surface, the cylinder body is formed with first to third piston guide portions. Each piston guide portion is formed with an odd number of grooves arranged at circumferentially equal distances. Each groove of each piston guide portion axially aligns with the corresponding grooves of the other piston guide portions. The circle including the bottoms of the grooves of the first guide portion has a diameter equal to or smaller than the rear opening of the cylinder body. The grooves of the first guide portion have a width gradually decreasing toward the front end thereof.

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Toyota, Japan

Kaoru Tsubouchi