| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a pneumatic booster capable of providing excellent braking feeling by realizing increase of hysteresis without causing increase of loss stroke before starting boosting action. <P>SOLUTION: A valve element 25 is structured with an elastic body. At the time of releasing a brake, a plunger 21 is returned in a direction of the arrow, and the valve element 25 is brought back with a breather valve 32 consisting of an inner peripheral valve seat 31 and the valve element 25 being closed, and the valve element 25 is estranged from the outer peripheral valve seat 33 and a most outer peripheral valve seat 34 to open a vacuum valve 35. However, as the valve element 25 is deformed by the pressure difference between a pressure of a negative pressure chamber in a connecting passage 36 and a pressure of a variable pressure chamber to a back pressure chamber 28 in a zone between the valve seats 33 and 34, the valve element 25 still keeps contacting with an outer collar part 33a of the valve seat 33 and delays to open the vacuum valve 35 even when a clearance d is made by taking the valve element 25 from the valve seat 33, and thus the braking feeling can be improved because of hysteresis increase. As these measures have no influence on closing the vacuum valve 35 and opening the breather valve 32 at inputting operational force, causing no increase it the loss stroke. <P>COPYRIGHT: (C)2003,JPO |
