| 摘要 |
PURPOSE:To enable a device to be operated in favorable and stable feeling by configurating the device in such a way that brake force can be boosted in proportion to force applied to a brake pedal, in addition, the output can be gradually increased after the force applied on the brake pedal has been released in a negative pressure type brake force booster. CONSTITUTION:The arrangement of a brake force booster is such that the inside of a shell is divided into a negative pressure chamber and a variable pressure chamber, a power piston 2 which moves to the axial direction depending on difference in pressure between the above mentioned two chambers, is provided, and a flexible poppet circular valve body 11 is also provided in the inner space of a cylindrical shaft 2b of the piston 2. The circular valve body 11 is pressed by a compression spring 16 against the circular end edge 14a of a plunger 14 which is provided to an input rod 13. In this case, an inner circular concave 10c is provided to form a circular 10d between the base 10b which is subjected to the compression spring 16 force of the above valve body 11 and the end surface 10a which is pressed against the upper end edge 14a. An orifice 20 which penetrates the above said end surface 10a, is provided on the circular flange 10d reaching to the inner circular concave 10c.
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