| 摘要 |
PURPOSE:To shorten the axial measure of a valve body by opening the front side end part of a variable pressure passage to the end face of a second cylindrical member forming a valve body, and fixing the cylindrical part of a front power piston fittingly to a first cylindrical member forming the valve body. CONSTITUTION:In this booster, a constant pressure chamber A and a variable pressure chamber B are partitioned at the front and rear of a front diaphragm 11, and a constant pressure chamber C and a variable pressure chamber D are partitioned also at the front and rear of a rear diaphragm 12. A space, formed more on the inner peripheral side than a ring seat part with which a first valve seat 16 and a valve component 20 are brought into contact and more on the outer peripheral side than a ring seat part with which a second valve seat 18 and a valve component 20 are brought into contact, is communicated with the variable pressure chamber D through a radial variable pressure passage 26 formed at a valve body 6, and this variable pressure chamber D is communicated with the variable pressure chamber B through a variable pressure passage 27. The front side end part of the variable pressure passage 27 is opened to the front side end face 38b of a second cylindrical member 38 forming the valve body 6, and the stepped cylindrical part 9A of a front power piston 9 is connected to a first cylindrical member 37 forming the valve body 6. |
