| 摘要 |
1,242,552. Fluid-pressure servomotor systems. ROBERT BOSCH G.m.b.H. Oct. 18, 1968 [Oct. 19, 1967], No.49427/68. Heading G3P. A pilot-operated pressure limiting valve comprises a control member 3 controlling a connection 8 between an inlet 4 and an outlet 5 and is characterized in that a throttle 30 is formed when the member 3 abuts against the face 29 of the pilot valve housing 15. In operation, fluid from inlet 4 passes via an extension 6 to a bore 18 and further to blind bores 25, 27. A fixed throttle 23 ensures that the member 3 is pressurebalanced in the position shown. If the inlet pressure rises above the value set for the pilot valve, the closure member 39 is lifted from its seat and fluid flows to exhaust via port 47. The reduction of pressure on the upper face of member 3 causes it to rise and expose the outlet 5 to the inlet 4. If the front face 26 of member 3 reaches its limit position on the plane surface 29, a second throttle is formed between groove 30 and the surface 29. Alternatively the throttle can be formed between a groove in the surface 29 and the plane upper surface of the member 3, or the throttle effect can be attained by surface roughness of the parts 3 and 29. When bore 22 is closed and a pin 20 is removed from bore 21, an external control fluid circuit may be connected to the bore 21 to control remotely the pressure limiting valve. |
