Patent ID: 8316891
Filing Date: 2012-11-27
Classification: B60T,F15B

Abstract:
1. A hydraulic pressure apparatus comprising: a cylinder formed at a housing; a port open to an inner peripheral surface of the cylinder and communicating with an exterior of the cylinder; a plunger member having a sealing member installed on an outer peripheral surface thereof and liquid-tightly and axially movably inserted into the cylinder, whereby the sealing member is passable over an opening of the port on the cylinder upon an axial movement of the plunger; and a pressure chamber formed between the cylinder and the plunger member into which a hydraulic pressure is introduced, wherein the housing includes: a hollow portion in communication with the port, extending outwardly in a radial direction from the port and cylindrically and concentrically formed with the port, the hollow portion having a diameter larger than an inner diameter of the port, and an annular thin portion formed between the inner peripheral surface of the cylinder and the hollow portion and surrounding concentrically the port in a radial direction, wherein the annular thin portion is deformed by outward deflection by being pushed outwardly in a radial direction of the cylinder from an inside of the cylinder centering on the port, within an area having a diameter smaller than the inner diameter of the hollow portion and wherein the opening of the port sinks outwardly from the inner peripheral surface of the cylinder, thereby to form a curved surface concentrically with the port at a root portion of the thin portion on the inner peripheral surface of the cylinder.