| 摘要 |
<p>A direct-acting, differential piston relief valve has a spring chamber pressurized with fluid from a passage through the piston. The fluid within the chamber is at the same pressure as that at the inlet valve and provides a valve closing pressure against the inner face of the piston. The piston face at the inlet valve has an annular extension. The inner circumference of this extension meets the spherical valve seat when the valve is closed. The diameter of the inner face of the piston is smaller than the diameter of the piston face annular extension. Inlet pressure working on this area difference produces the hydraulic force which is opposed by the spring. No piston face area is exposed to forces tending to close the valve due to Bernoulli effects when the valve begins to open. The spring within the spring chamber has spring guides at each end which contain a ball. The ball transmits the spring force to the piston on one end and a sealed closure at the other end.</p> |
