| 摘要 |
<p>An automatic bleed valve 34 for bleeding air from a pressurized liquid reservoir includes a piston 4 in a piston chamber 25 located in a flow channel leading from the reservoir. A first orifice 6 is provided in a passage 24 through the piston 4, and the piston 4 is urged upstream by a resilient spring 8. A second orifice 16 downstream of the first, is located in the flow channel. When gas is expelled from the reservoir, the resilient spring 8 will retain the piston 4 in an equilibrium region, allowing the gas to be bled from the reservoir through the flow channel. When liquid begins to flow through the flow channel, the pressure differential over the piston 4 increases, because the pressure drop across an orifice is greater for a liquid than a gas, and this causes the piston 4 to move against a seat 23 of a poppet 5 and seal off the flow channel and the hydraulic reservoir. The diameters of the orifices may be chosen to maximize the increase in pressure differential. <IMAGE></p> |
