JPS5790246A - Dual-spring acting master cylinder - Google Patents

Abstract

PURPOSE: To prevent a dull braking at a sudden step on a brake by providing a choke, which is disposed in a passage communicating an auxiliary pressure chamber and a reservoir, as a variable one whose effects depends on an increasing rate in pressure inside the auxiliary pressure chamber.

CONSTITUTION: An auxiliary pressure chamber 12 of a master cylinder 1 is communicated by a large hole 38 with a space inside a boss 5 which is connected to a reservoir. A valve equipment 39 is fixed inside said large hole 38 tightly to liquid. A major part 40 of the valve equipment 39 is made up of a large diameter part 42 and a cylindrical part 43. A valve port 44 and many small holes 45 are formed through both the parts 42, 43 and the latter part 42, respectively. Steps 47, 48 are formed at the lower half part of the valve port 44, with a ball 51 pressed by a spring 53 on the step 47 as a seat 49. A rubber member 54 which is composed of a cylindrical part 57 and a plate 55 in close contact with the lower face of the large diameter part is fit under the major part 40. A center hole 59 is made through the cylindrical part 57 and a choke passage 60 is formed in the middle of said hole 59. Notched parts 62, 63 communicate a clearance 65 with a chamber 64 so that a pressure in the chamber 63 may vary the area of the choke 60.

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