Hitachi, Ltd.

Hitachi Automotive Systems, Ltd.

Tokico, Ltd.

Kabushiki Kaisha Hitachi Seisakusho

Kabushiki Kaisha Hitachi Seiksakusho

Tomonori Mouri

Naganori Koshimizu

Takato Ogiwara

Yasuhiko Amari

Hiromi Ando

Takayuki Kinoshita

Daigoro Kamase

Yasutoshi Nagatsuyu

Yoshinari Iwai

Provided is a reservoir having first and second partitions. The first partitions partition a brake reservoir chamber and clutch reservoir chambers. The first partitions extend in a length direction of the vehicle and are formed uprightly along the sidewalls. The second partitions connect the first partitions and the sidewalls adjacent to the first partitions. The second partitions are formed uprightly at middle positions of the respective sidewalls in the length direction of the vehicle. The brake reservoir chamber and the clutch reservoir chambers are formed to face the sidewalls.

Reservoir and master cylinder

A master cylinder comprising a large diameter pressurizing chamber and a small diameter hydraulic chamber, a control valve device in which a control valve body releases a hydraulic pressure in the large diameter pressurizing chamber to a reservoir side such that the hydraulic pressure in the large diameter pressurizing chamber is gradually reduced in accordance with a rise in a hydraulic pressure in the small hydraulic chamber, and a check valve device comprising a check valve chamber communicating with an relief passage, which releases a hydraulic pressure in the large diameter pressurizing chamber to the reservoir via the control valve device, and with a small diameter hydraulic chamber, respectively, and a check valve body accommodated in the check valve chamber for permitting flow of a brake fluid from the relief passage to the small hydraulic chamber, and for preventing flow of the brake fluid in a reverse direction.

Master cylinder

A master cylinder that can prevent impairment of a piston seal, and a method of producing the master cylinder are provided. A master cylinder has a circumferential groove () in which a piston seal is provided, the piston seal having an outer circumference which enables operating fluid to be supplied, and a communication groove () which opens into the circumferential groove () and extends from the circumferential groove () toward a bottom portion of a cylinder body () to connect a pressure chamber and the circumferential groove (). The communication groove () is formed with its center made eccentric relative to the center of the circumferential groove (). A chamfered portion () is formed over an entire extent of a corner portion formed by the circumferential groove () and the communication groove (), along a circular path concentric with the communication groove ().

Master cylinder, master cylinder body, and method for producing master cylinder

A master cylinder designed to facilitate an operation of assembling and adjusting a check valve is provided. A supply passage for supplying operating fluid from a reservoirto a pressure chamberis formed in a cylinder bodyconnected to the reservoir. A bypassfor bypassing the supply passage connecting the reservoirand the pressure chamberis formed and provided with a check valve systemadapted to open when a pressure in the pressure chamberis lower than that in the reservoir. A valve caseand a covering memberconstitute a cartridge, which accommodates a valve bodyand an urging spring, so as to form a check valve system. The cartridgeis placed in a valve chamberof the bypass

Master cylinder, method for manufacturing a master cylinder, and check valve system of the master cylinder

A master cylinder including a cylinder body having a tubular shape with a closed end; and a piston having one side slidably inserted into the cylinder body and another side that projects from the cylinder body. The piston and the cylinder body define a pressure chamber for generating hydraulic pressure. The master cylinder also includes a protecting member for covering the side of the piston projects from the cylinder body. The protecting member is adapted to extend and contract, and limit backward movement of the piston.

A piston seal is provided in a circumferential groove formed in a cylinder body. The piston seal is capable of sealing a pressure chamber, which supplies fluid pressure to a discharge passage, from a supply passage, which communicates with a reservoir. The piston seal comprises: an annular base portion; an inner circumferential lip portion projecting from an inner circumferential side of the base portion and being in slidable contact with an outer circumferential surface of a piston; an outer circumferential lip portion projecting from an outer circumferential side of the base portion and being in abutment with the circumferential groove of the cylinder body; and an intermediate projecting portion which is formed between the inner circumferential lip portion and the outer circumferential lip portion of the base portion and which is projected beyond the outer circumferential lip portion. Cutout grooves are formed on a tip side of the intermediate projecting portion. Therefore, when releasing air, a sufficient amount of brake fluid can be supplied through a gap between the piston seal and a bottom surface of the circumferential groove, and the cutout groove. As a result, the number of repetitions of an air releasing operation can be minimized.

A large-diameter bore portion is formed in a portion defining a pressure chamber in a cylinder body on a side opposite to a circumferential groove relative to a slidable inner-diameter portion. A communication groove capable of allowing communication between the circumferential groove and the large-diameter bore portion is formed in an upper portion of the slidable inner-diameter portion. A point of maximum depth of the communication groove is located radially outward of a bottom of the circumferential groove. The master cylinder of the present invention is capable of preventing the supply of a brake fluid from being restricted in an evacuation process, and enables a reduction in length to be machined of the communication groove, thus reducing the time for machining and suppressing an increase in cost.

A master cylinder has a cylinder member in the shape of a cylinder, one end of which is closed, and a piston inserted in the cylinder member to form a pressure chamber in the cylinder member. The cylinder member is formed with a port for providing communication between the pressure chamber and a reservoir. The port is formed during casting of the cylinder member, thereby eliminating the need to form the port by boring, and forming the port into an elongated-hole shaped sectional configuration.

Master cylinder and method of producing the same

A master cylinder comprises a cylinder body in a cylindrical form having one end closed and including a discharge passage and a supply passage for a brake fluid, the supply passage being communicated with a reservoir. A piston is slidably disposed in the cylinder body, so as to form a pressure chamber for supplying a fluid pressure to the discharge passage. A piston seal is provided in a circumferential groove formed in the cylinder body, which has an inner circumferential surface thereof in slidable contact with the piston and is capable of sealingly disconnecting the supply passage and the pressure chamber. The cylinder body includes a communication groove which opens into the circumferential groove and extends from the circumferential groove toward the closed end of the cylinder body to thereby connect the circumferential groove and the discharge passage. The communication groove is formed outwardly beyond a bottom surface of the circumferential groove relative to a radial direction of the cylinder body.

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.

Growing community of inventors

Kai, Japan

Tomonori Mouri