| 摘要 |
<p>A diaphragm pump (10) driven by hydraulic fluid actuated by a piston (22) has a multifunction valve (30). The multifunction valve can act as a relief valve with its poppet (74), a gas purge valve (80) and a bleed valve (50). The bleed valve and the gas purge valve have coaxial seeling surfaces and the bleed valve is arranged inside the purge valve. The bleed valve is a ball valve, with its ball (52) traveling between valve seats (58, 60) to let a small amount of working fluid escape during each piston stroke. Air, which may have been accumulated in passage (46), escapes together with the working fluid. The purge valve allows for quick release of large gas volumes by manual actuation. The relief valve surrounds the bleed and purge valves and is a spring (102) actuated valve with the valve seat (104) to allow the escape of working fluid through clearances between flat surfaces (124) and (122).</p> |
