| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To enhance responsiveness when a master cylinder is operated abruptly. <P>SOLUTION: In this master cylinder wherein a pressure chamber Rp2 formed by a cylinder housing 10, a seal cup 21 and a piston 32 is communicated with an atmospheric-pressure chamber Ra2 through a communication passage 32a formed in the piston 32, under the condition where the piston 32 is located in an original position, and wherein the communication between the communication passage 32a and the atmospheric-pressure chamber Ra2 is blocked with the seal cup 21 under the condition where the piston 32 is moved from the original position to a moving direction by a prescribed distance, a stepped hole of which the end part opened in an outer circumferential face of a hollow end part 32b of the piston 32 is made large in its diameter (32a2), and of which the end part communication-opened in an inner circumferential face (pressure chamber Rp2) of the hollow end part 32b of the piston 32 is made small in its diameter (32a1) is adopted as the communication passage 32a, and a passage cross-sectional area of the small-diametric part 32a1 is set to exhibit a contraction effect in the small-diametric part 32a1 in the stepped hole. <P>COPYRIGHT: (C)2004,JPO</p> |
