Jidosha Kiki Co., Ltd.

Junichi Ohki

Hidefumi Inoue

Shintaro Uyama

Haruo Suzuki

Atushi Satoh

Yasuo Tsuyuki

Yuzoh Gotoh

Takanao Kamei

In the negative pressure booster equipment 1 according to the present invention, a groove 27 is provided on the inner peripheral beads 14a and 16a of the diaphragms 14 and 16, fixed on the valve body 8 and forming the power pistons in order to communicate the variable pressure chambers 5b and 7b divided by the diaphragms 14 and 16 with the passages 26 and 28 corresponding to the variable pressure chambers 5b and 7b. Accordingly, the air passages are opened to the variable pressure chambers 5b and 7b through the groove 27 formed on the beads 14a and 16a of the diaphragms 14 and 16. According to this invention, therefore, there is no need to provide wide gap between the fixed portion of the beads and the center plate in order to open the air passages to the variable pressure chambers. This makes it possible to shorten overall length of the negative pressure booster equipment 1.

Negative pressure booster equipment

A brake booster is disclosed which reduces an idle stroke of an input shaft. A key member which is mechanically coupled to a valve plunger which forms part of a valve mechanism is provided with an elastic member so that when the brake booster is inoperative, the elastic member on the key member abuts against a shell and a valve body, respectively, thereby limiting a retracting movement of the valve body. Under this condition, a retracting movement of the key member is allowed by an elastic deformation of the elastic member if the input shaft is pulled rearward to cause a retracting movement of the valve plunger and the key member.

Brake booster with key member having an elastic member

The invention relates to a locking arrangement for a key member used in a brake booster. A key member includes an arcuate portion which surrounds substantially one-half the perimeter of a valve body, and engaging recesses are formed at the opposite ends of the arcuate portion on the inner side. A retainer surrounds substantially one-half the perimeter of the valve body at a location opposite to the arcuate portion of the key member. The opposite ends of the retainer are formed with engaging pawls on the outer side for engaging with the engaging recesses under the resilience of the retainer. Accordingly, by merely assembling the key member and the retainer with the valve body, the engaging pawls of the retainer can be automatically engaged with the engaging recesses in the key member, thereby preventing the withdrawal of the retainer and the key member from the valve body.

Brake booster

A power servo booster having front and rear shells coupled together to reciprocally provide a power piston therein. A flexible diaphragm has an inner peripheral surface secured to the power piston and an outer peripheral surface secured to the coupling portion between the front and rear shells. The diaphragm divides the shell into negative pressure chamber and an atmospheric pressure chamber. A portion of the diaphragm confronts the rear face of the power piston and extends therefrom toward the front shell and then is folded back to provide a folded portion defined from outer end portion of the power piston. The folded portion is continuous to a contacting portion of the diaphragm which contacts inner wall of the shell. At least one of the contacting portion and the portion contacting the outer end of the power piston provides a thick wall portion as an high rigidity member.

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Saitama, Japan

Junichi Ohki