| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a negative pressure type booster having good responsiveness at sudden operation and performing silent operation during normal operation, capable of providing an air purifying function anytime and avoiding contamination due to air of a structural member existing at a portion from a purifying filter to a pressure changing chamber. <P>SOLUTION: The negative pressure type booster has the purifying filter 80 provided on an air introduction passage Po for introducing the air to an atmospheric valve seat 41a, for purifying the air, and a muffling filter 90 made of material having a density higher than that of the purifying filter 80 and arranged at an upstream side of the purifying filter 80, while having a housing 10, a movable partition wall 20, a power piston 30, an input member 40, an output member 50, and a control valve 70. An opening/closing valve V for closing when advancing quantity with regard to the power piston 30 of the input member 40 is a prescribed value or less and for opening when the advancing quantity is larger than the prescribed value, is interposed in a bypass passage P1 bypassing the muffling filter 90 to introduce the air. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
