Aisin Seiki Kabushiki Kaisha

Akimoto Okada

Toshihiro Nakano

Kaoru Tsubouchi

Naoyasu Enomoto

Hideaki Iijima

A master cylinder includes a cylinder housing having a rearwardly opening inner bore, a piston having a forwardly opening bore positioned in the inner bore of the cylinder housing, a spring disposed in the inner bore of the piston, a stopper supporting a front end of the spring, a retainer disposed in the inner bore of the piston and supporting a rear end of the spring, and a rod connecting the retainer and the stopper while allowing the spring to compress in the axial direction. A plurality of projection portions are formed on the outer circumferential portion of the retainer and the retainer is pressed into the inner bore of the piston via the projection portions.

Master cylinder

A brake master cylinder which prevents a contact between a projection of a spring retainer and a stopper of a sleeve when a piston is suddenly retracted by an operation of a pressure applying device of a brake system or by an air relieving operation to offer a high reliability without deformation and damages of the spring retainer and the sleeve. A groove extended in axial direction is provided on the sleeve. A distance between a rear end surface of the groove and a radial projection of a first spring retainer when the brake is not applied corresponds to the total of a distance of a retracting distance of a second piston from the position defined by the non-braking operation to a position where a piston port and an opening of a reservoir communication conduit are overlapped and a predetermined additional distance.

Brake master cylinder

A brake master cylinder for a vehicle brake system in which the assembling precision of a guide and a cup seal, the structure of a communication conduit, and the structure of a cylinder cap and the guide are improved to thereby improve the performance of the brake master cylinder while also reducing the cost and improving the sealing structure between a body and the cylinder cap to thus reduce the size of the cylinder cap. The brake master cylinder includes the cylinder cap positioned in an internal bore opening portion of the body, a first piston inserted into a cylinder housing through the cylinder cap and slidably supported by the guide in the axial direction, a second piston positioned coaxially with the first piston at the front of the first piston and slidable in the axial direction in the cylinder housing, and a cup seal at the front of the guide for liquid-tightly sealing a first pressure chamber formed between the first piston and the second piston. The guide and the cup seal coaxially engage the inner bore of the cylinder cap.

A brake master cylinder includes a cylinder housing formed by a cylinder body and a cap, a first guide member, a second guide member, a sleeve, a first piston and a second piston. To achieve accurate concentricity between a bore of the first guide member and a bore of the sleeve, and between a bore of the second guide member and the bore of the sleeve, the first guide member is coaxially provided in a bore of the cap, the second guide member is coaxially provided in the cylinder bore and has a first bore at its front side and a second bore at its rear side, and the sleeve is coaxially fitted into the bore of the cap at its rear end and is coaxially fitted into the second bore of the second guide member at its front end. The first piston is fitted into the cylinder housing and is slidably supported in the axial direction by the bore of the first guide member and the bore of the sleeve, the second piston is provided in front of the first piston coaxially and is slidably supported in the axial direction by the first bore of the second guide member and the bore of the sleeve.

A master cylinder having variable input/output characteristics includes a cylinder body in which is formed a cylinder bore and a piston fitted in the cylinder bore and movable upon brake operation. The piston is divided into a front portion and a rear portion, with a pressure chamber being defined at the front side of the front portion and an auxiliary chamber being defined at the rear side of the front portion. The auxiliary pressure chamber is located at the same position as the rear portion of the piston. A first changeover valve is provided between the auxiliary pressure chamber and the pressure chamber to establish and interrupt fluid communication between the auxiliary pressure chamber and the pressure chamber.

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Anjo, Japan

Akimoto Okada