Abstract: To provide a plunger type master cylinder capable of reducing invalid stroke and preventing residual pressure without impairing durability of a seal ling (70). A piston (91) of the master cylinder has a recess (93) at its outer peripheral surface and a relief port (900) in its recess (93). The seal ring (70) has a seal coupling part (70s) on the inner periphery of the distal end part of an inner peripheral lip (701). The seal coupling part (70s) is located at the opening of the relief portion (900) on the piston (91) side when the brake is in a non-operating position. The distance between said seal coupling part (70s) and said relief port (900) is short. The seal ring (70) additionally has first and second projection parts (7006, 7002) on the inner peripheral surface of the inner peripheral lip (701). By this, a flow passage for working fluid can be obtained on the inner periphery side of the inner peripheral lip (701).

Abstract: A master cylinder including a cylinder body having a cylindrical bore and an opening in the circumferential wall for a relief port communicating with the interior of hydraulic reservoir. A piston is slidably inserted into the cylindrical bore to form a hydraulic pressure generating chamber in the cylindrical bore. A cup seal is provided with an inner circumferential lip portion contacting with the piston, an outer circumferential lip portion slidably contacting with the inner circumferential wall of the cylindrical bore, and a base portion connecting the lip portions, which are so arranged as to face to the hydraulic pressure generating chamber. The cup seal cuts the communication between the hydraulic pressure generating chamber and the hydraulic reservoir through the relief port when the top end of the outer circumferential lip portion passes by the relief port.

Abstract: In a master cylinder including: a cylinder body having a cylindrical bore and an opening made in the circumferential wall, for a relief port communicating with the interior of hydraulic reservoir, a piston inserted slidably into said cylindrical bore to form a hydraulic pressure generating chamber in said cylindrical bore; and a cup seal having an inner circumferential lip portion contacting with said piston, an outer circumferential lip portion slidably contacting with the inner circumferential wall of said cylindrical bore, and a base portion connecting said lip portions which are so arranged as to face to said hydraulic pressure generating chamber, whereby said cup seal cuts the communication between said hydraulic pressure generating chamber and said hydraulic reservoir through said relief port when the top end of said outer circumferential lip portions passes by said relief port, the improvement in which means for rotating said cup seal relative to said cylindrical bore with the movement of said piston i

Abstract: This invention not only positively reduces the vibrations and noises due to pulsation pressure generated by a hydraulic pressure pump 10, but also effectively prevents the generation of foreign sounds that may occur when a liquid-operated booster 90 is abruptly activated. For this purpose, a throttle valve unit 80 (180, 280) for greatly reducing the flow area until the pressure differential or flow rate reaches a predetermined value is provided between an accumulator 70 for accumulating pressurized liquid and the liquid-operated booster 90 which utilizes the pressurized liquid as an operation source. When the pressure accumulated within the accumulator 70 is at a predetermined value or less, the throttling function of the throttle valve unit 80 (180, 280) is cancelled.

Abstract: A hydraulic booster for a vehicle and more particularly an improved hydraulic booster with improved brake-relieving action, among other improvements.

Abstract: A pump apparatus includes a plunger, an eccentric cam for moving the plunger toward a pressure chamber, a drive shaft supporting the eccentric cam, and an output shaft of a motor for imparting a rotational force to the drive shaft. A convex portion is formed on one end of one of the drive shaft and the output shaft whereas a concave portion is formed in one end of the other of the two shafts. The convex portion is fitted in the concave portion to interconnect the drive shaft and the output shaft. The convex portion is fitted in the concave portion with a clearance therebetween. A holder member for always holding the convex portion and the concave portion in engagement with each other in the direction of rotation of the drive shaft is provided at an area of fitting between the convex portion and the concave portion. With this arrangement, noises resulting from the impingement of one of the convex portion and the concave portion upon the other during the operation of the pump apparatus are eliminated.

Abstract: In a hydraulic reservoir of a master cylinder for vehicle including: a main body having an internal space for storing brake fluid; a float provided with permanent magnet, so arranged as to be vertically movable in the internal space of the main body; a reed switch attached to the outside surface of the main body, the reed switch being actuated by magnetic force of the permanent magnet, when the float with permanent magnet is positioned under a predetermined level; and a hollow for attaching the reed switch to the outside surface of the main body, the reed switch is supported by a support member in the hollow, a rubber bush is tightly and elastically fitted to the inside wall of the hollow and a fixing member is so fitted to the hollow as to push the rubber bush to the support means, terminals of the reed switch being inserted tightly through holes of the rubber bush whereby the reed switch is held in the hollow.

Abstract: A plastic piston of master cylinder has a first member having a small diameter portion and a second member having a large bore portion. Excess welding resin is prevented from being leaked into a seal ring mounting groove formed on a part of the outer peripheral surface of the small diameter portion by provision of welding portions in the form of a space defined between an outer peripheral surface of the small diameter portion of the first member and the large bore portion of the second member, and a gap defined between a tip end of the small diameter portion of the first member and the bottom of the large bore portion, the space and gap being provided respectively for preventing the excess welding resin from being leaked into the seal ring mounting groove. The plastic piston has no parting lines along the seal ring mounting groove which results in achieving a superior seal effect.

Abstract: In a hydraulic pressure control valve for use with a brake master cylinder, a hollow body of one-piece structure has an internal stepped bore through which outlet and inlet bores formed respectively in one and other ends of the body communicate with each other. A mounting portion to the master cylinder is provided adjacent the other end of the body. A piston is arranged in the stepped bore for reciprocative movement therealong in response to hydraulic pressure from the master cylinder. One end of the piston remote from the outlet bore has an end face serving as a valve seat. A substantially tubular cap element is arranged in the inlet bore and supports the one end of the piston. The cap element is fixed to the body by fixing arrangement which is accompanied with no relative rotation between the cap element and the body.

Abstract: A fluid pressure control valve includes a housing having an inner hole and a plunger movably disposed in the inner hole, the housing having inlet and non-pressure chambers defined herein at one end of the plunger and an outlet chamber defined therein at the opposite end of the plunger, the housing also having a passage communicating the outlet chamber with the inlet chamber. A valve device is disposed in the passage and openable and closable in response to movement of the plunger. A preloading spring is disposed in the housing for normally urging the plunger in a direction to open the valve device. The housing comprises a cylindrical member having one open end and a cover member closing the open end. A spring seat is disposed in the cylindrical member in engagement with the cover member, the preloading spring acting between the spring seat and the plunger. The spring seat is force-fitted in the inner hole of the housing or in the cover member.

Abstract: A master cylinder includes a cylinder of one-piece construction made of a synthetic resin and including a cylinder body having an axial internal bore therein. At least one mounting flange extends perpendicular to an axis of the cylinder body, the mounting flange being adapted to be secured to a support structure to mount the master cylinder thereon. A plurality of ribs are formed integrally with and extends radially outwardly from the outer peripheral surface of the cylinder body in circumferentially spaced relation, the ribs also extending along the axis of the cylinder body. The mounting flange is connected to radial outer ends of the ribs. A piston received in the internal bore for sliding movement therealong.

Abstract: A hydraulic reservoir in a tandem master cylinder includes a main portion defining a fluid reservoir chamber for reserving brake fluid, two fluid supply portions defining fluid paths under the main portion, the fluid supply portions being contiguous with the main portion and an opening formed at the top, the two fluid supply portions being connected to two fluid connection portions of a tandem master cylinder body.

Abstract: In a brake control apparatus which comprises two brake systems for supplying pressurized fluid from a brake master cylinder to brake wheel cylinders through conduit systems independent from each other, one of said two brake systems including a first brake control valve which is able to check the fluid flow towards said brake master cylinder from one of said brake wheel cylinders on detecting an inclined roadway, and is able to open and close in accordance with clutch operation, another of said two brake systems includes a second brake control valve which is able to check the fluid flow towards said brake master cylinder from another of said brake wheel cylinders to response to operation of said first brake control valve.

Abstract: A hydraulic reservoir for tandem master cylinder includes a body formed by upper, lower and side walls, two brake fluid reserving chambers formed by two partitioning walls in the body, and oblong passages formed by the side walls and ancillary walls integrally formed with the partitioning walls to make the two brake fluid reserving chambers communicate with each other, the oblong passages being open to the two brake fluid reserving chambers, respectively, having bottoms higher by a predetermined length than the lower wall, and having at least such length that a flow amount of brake fluid between the two brake fluid reserving chambers is limited to a predetermined value on the inclination of the brake fluid level relative to the body.