Patent ID: 8141959

Claim:
A vehicle brake hydraulic pressure control unit comprising: a base body comprising: a brake fluid flow path; and a mounting hole portion comprising: a bottom sealing surface formed on a bottom surface thereof; and an inner circumferential sealing surface formed on an inner circumferential surface thereof; and an assembled part which is assembled into the mounting hole portion so as to communicate with the flow path, the assembled part comprising: a locking groove formed on an outer circumferential surface of a lid portion by setting back a relevant location into the outer circumferential surface along a circumferential direction, the lid portion above the locking groove having a diameter smaller than the lid portion below the locking groove; a lower end sealing portion formed on a lower end surface thereof and hermetically contacting with the bottom sealing surface of the mounting hole portion to form a lower side sealing portion; and an outer circumferential sealing portion formed on an outer circumferential surface thereof and hermetically contacting with the inner circumferential sealing surface of the mounting hole portion to form a circumferential sealing portion, wherein a hermetic accommodation space is defined by the lower side sealing portion and the circumferential sealing portion, wherein: a lower end portion of the assembled part comprises: a press-fit portion which is press fitted in the inner circumferential sealing surface of the mounting hole portion; and a small diameter portion whose diameter is smaller than a diameter of the press-fit portion, the accommodation space is further defined by an outer circumferential surface of the small diameter portion and an inner circumferential surface of the mounting hole portion, the small diameter portion is formed on a lower side of the press-fit portion, a lower end surface of the small diameter portion is brought into abutment with the bottom sealing surface of the mounting hole portion, the press fit portion comprises the lower end sealing portion, and an outer diameter of the press-fit portion is made equal to or slightly larger than a diameter of the mounting hole portion at a cylindrical abutment portion or a hole diameter of the cylindrical abutment portion, the lower end sealing portion is the small diameter portion formed on a lower side of the press-fit portion; and a lower end surface of the small diameter portion, which comprises the lower end sealing portion, is brought into abutment with a bottom surface of the mounting hole portion over its entirety along a full circumference thereof.