| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To enhance brake liquid feed ability from a reservoir to a pressure chamber of a plunger type master cylinder for pressurizing the brake liquid in the pressure chamber by sliding on an inner periphery of a cup in which a piston is retained on a cylinder body at execution of automatic brake, to further accurately determine port idle and to realize maintaining reliability of the cup. <P>SOLUTION: Annular walls 15, 16 having larger inner diameters than outer diameters of a primary piston 2 and a secondary piston 5 are provided at a position supporting a cup back surface of the cylinder body 1. Further, communication grooves 22, 23 and a plurality of piston ports 9, 10 penetrated into the piston from the communication grooves 22, 23 are provided on the circumference of the outer periphery of the primary piston 2 and the secondary piston 5 respectively. At non-operation of the piston, the communication grooves are positioned at the inside of the annular walls 15, 16 to form an annular space C having a large passage area at the inside of the annular walls 15, 16. A first pressure chamber 3 and a second pressure chamber 6 are communicated with a reservoir 8 through the annular space C respectively. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
