HYDRAULIC PRESSURE BOOSTER

摘要

PURPOSE:To simplify construction and reduce the quantity of parts by constituting an outlet valve with stepped holes on a valve piston for making continuous and shutting off communication between an oil hole on a booster piston and an oil chamber depending upon the relative shift of the valve piston and the booster piston. CONSTITUTION:A guide hole 51 is punched ranging over the entire length of the booster piston 35 of a hydraulic pressure booster. This guide hole 51 is formed with a large bore part 51a from the front end of the booster piston 35 to the intermediate part of a large bore piston part 35a in the booster piston 35, and a small bore part 51b continuous to the large bore part 51a. A valve piston 52 is so inserted as to come in slidable contact with the internal surface of the small bore part 51b. And a ring- shaped oil chamber 53 is formed between the inner surface of the large bore part 51a of the guide hole 51 and the outer surface of the valve piston 52, and an outlet valve 54 is provided between the oil chamber 53 and an output hydraulic pressure chamber 38. This outlet valve 54 is constituted in such a way that a large bore part 52a capable of closing an oil hole 55 and a small bore part 52b capable of making the oil chamber 53 and the oil hole 55 continuous to each other are provided in the valve spindle 52 without any step.