To provide a cup inner diameter slide type master cylinder having a simple structure with high reliability and ensuring sufficient suction property of a brake liquid relative to a pressure chamber during the returning of a piston and at controlling of an automatic brake such as vehicle stability control.
In the master cylinder, annular walls 17, 18 integrally constituted with a cylinder body 1 are provide behind primary cups 13, 15. Inner diameters of the annular walls 17, 18 are made larger than an inner diameter of the cylinder and annular passages 19, 20 are formed between the annular walls, a primary piston 2 and a secondary piston 5. Further, communication passages 23, 30 with a reservoir 10 having gaps with the pistons 2, 5 larger than the annular passages 19, 20 are provided at a rear side of the annular walls 17, 18. Piston ports 8, 9 are communicated with the reservoir 10 through the annular passages 19, 20 at non-operation.
INOUE YOJI
MITA KATSUHIRO
SUZUKI KOJI
Higashio Masahiro
Torii Kazuhisa