MASTER CYLINDER

摘要

In a master cylinder, a piston seal provided in a circumferential groove includes an annular base section, an inner circumferential lip section protruding from an inner circumferential side of the base section to come into sliding contact with an outer circumferential surfaced of a piston, an outer circumferential lip section protruding from an outer circumferential side of the base section to abut the circumferential groove, and an intermediate protrusion section protruding from a portion between the inner circumferential lip section and the outer circumferential lip section of the base section to a position further forward than the outer circumferential lip section. At least one inner circumferential side groove extending in an axial direction and opened at a front end side of the intermediate protrusion section is formed in a surface of the inner circumferential lip section side of the intermediate protrusion section.

主权项

1. A master cylinder comprising:
a cylinder main body formed in a bottomed cylindrical shape and having a discharge path of brake liquid and a supply path configured to come in communication with a reservoir of brake liquid; a piston movably disposed in the cylinder main body and configured to form a pressure chamber between the cylinder main body and the piston to supply liquid pressure into the discharge path; and a piston seal provided in a circumferential groove formed in the cylinder main body and configured to allow an inner circumference to come into sliding contact with the piston to seal between the supply path and the pressure chamber, wherein the piston seal includes: an annular base section; an inner circumferential lip section protruding from an inner circumferential side of the base section to come into sliding contact with an outer circumferential surface of the piston; an outer circumferential lip section protruding from an outer circumferential side of the base section to abut the circumferential groove of the cylinder main body; and an intermediate protrusion section protruding from a portion between the inner circumferential lip section and the outer circumferential lip section of the base section to a position further forward than the outer circumferential lip section, and wherein at least one inner circumferential side groove extending in an axial direction and opened at a front end side of the intermediate protrusion section is formed in a surface of the inner circumferential lip section side of the intermediate protrusion section.