| 摘要 |
PROBLEM TO BE SOLVED: To provide a negative pressure booster in which a diaphram is not damaged by a cut edge even if an outer peripheral edge of a booster piston is a cut edge without bend.SOLUTION: On a booster shell 1, a diaphram 5 dividing an inside of the booster shell 1 into a negative pressure chamber 2 on a front side and an operation chamber 3 on a rear side, is provided in an extended manner. On a front surface of the diaphram 5, a booster piston 4 for receiving advance thrust of the diaphram 5 generated by differential pressure between the negative pressure chamber 2 and the operation chamber 3 and operating a master cylinder M attached to the booster shell 1, is provided in an overlapped manner. An outer peripheral edge 4a of the booster piston 4 is a cut edge, and an annular thicker part 5c whose thickness is thicker than that of a bending part 5a and a piston pressing part 5b, is formed on a connection of the bending part 5a and the piston pressing part 5b of the diaphram 5. In addition, on the thicker part 5c, an annular groove 28 holding the outer peripheral edge 4a of the booster piston 4 is provided. |
