液壓閥畢業(yè)設(shè)計(jì)外文翻譯-資料下載頁(yè)
2024-12-03 16:24本頁(yè)面
【導(dǎo)讀】液壓回路中的壓力控制閥是用來(lái)確?；芈分胁煌糠值膲毫_(dá)到我們的預(yù)期值。力控制閥通過(guò)以下幾種方式實(shí)現(xiàn)我們的預(yù)期值：把高壓回路中的流體通過(guò)低壓區(qū)，來(lái)限制高壓區(qū)的壓力：分流到其他區(qū)域。這類(lèi)閥可分為安全閥、溢流閥、平衡閥、順序閥和卸荷閥。分流型閥是可以減壓的。衡閥是常閉式的，兩通閥處于常開(kāi)或半開(kāi)狀態(tài)以完成其工作任務(wù)?？梢韵拗棺罱K阻止油液進(jìn)入出口回路。任何一種類(lèi)型閥工作，都能自動(dòng)調(diào)節(jié)阻尼孔的大。小進(jìn)行壓力控制。有自我調(diào)節(jié)的能力，主要依靠外部油源的信號(hào)進(jìn)行調(diào)節(jié)。而節(jié)流閥、減壓閥、平衡閥和。種閥保護(hù)管路和設(shè)備，以免由于壓力過(guò)大而損壞。單向平衡閥這種閥維持油液一個(gè)方向的流體阻力，而另一個(gè)方向自由流動(dòng)。壓力開(kāi)關(guān)由油液的壓力進(jìn)行控制，同時(shí)也能對(duì)油液的壓力的變化做出相應(yīng)的反應(yīng)。先導(dǎo)式溢流閥的完全符號(hào)，包括基本部分和相關(guān)控制。溢流節(jié)流型節(jié)流閥是帶過(guò)載保護(hù)裝置的壓力補(bǔ)償控制閥，它有一個(gè)常閉的節(jié)流口，
【正文】 hange in the work load would affect the feed rate. Pressure pensated flow controls are further classified as restrictor and bypass types. Both utilize a pensator or hydrostat to maintain a constant pressure drop across an adjustable throttle. The ByPass Typebines overload protection with pressure pensated control of flow. It has a normally closed hydrostat which opens to divert fluid, in excess of the throttle setting, to the tank. Pressure required by the work load is sensed in the chamber above the hydrostat and together with a light spring tends to hole it closed. Pressure in the chamber below the hydrostat increase duo to restriction of the throttle and cause is to raise diverting any excess flow to tank when the difference in pressure is sufficient to overe the spring. This difference, usually 20 psi, is maintained across the throttle providing a constant flow regardless of the work load. Some horsepower saving is acplished in that the pump need operate at only 20 psi above work load pressure. Overload protection is provided by an adjustable spring loaded poppet which limits the maximum pressure above the hydrostat, causing it to function as a pound relief valve whenever work load requirement exceed its setting. The bypass flow control can only be used in a meterin circuit. If used for metering out, exhaust oil which could not get through the throttle would be diverted to tank permitting the load to run away. The Restrictor Type Flow Controlalso maintain a constant 20 psi differential across its throttle by means of a hydrostat. In this valve, the hydrostat is normally epen and tends to close off blocking all flow in excess of the throttle setting. In these units the work load pressure acts with a light spring above the hydrostat to hold it open. Pressure at the throttle inlet and under the hydrostat tend to close it, permitting only that oil to enter the valve that 20 psi can force through the throttle. Because of their tendency close off when flow tales to exceed the throttle setting, restrictor type valves may be used in meterin, meterout and bleedoff circuits. Unlike the bypass type , two or more restrictor valves may be used with the same pump since the excess pump delivery returns to tank through the relief valves. When placed in cylinder lines an integral check valve is optional to provide free flow for a rapid return stroke. One would not be required for valves placed in the main supply line, the tank line of a directional valve or when they are used in bleedoff circuits. Temperature Compensated Flow Control Valve Flow through a pressure pensated flow control valve is subject to change with variations in oil temperature. Later design Vickers valves incorporate a temperature. Although oil flows more freely when it is hot, constant flow can be maintained by decreasing the size of the throttle opening as the temperature rises. This is acplished through a pensating rod which lengthens with heat and contracts when cold. The throttle is a simple plunger that is moved in and out of the control port. The pensating is installed between the throttle and its adjuster. This design also is available with a reverse freeflow check valve. Remote Flow Control Valves Remote flow control valves permit adjustment of the throttle size by an electrical signal. The throttle spool is linked to armature of a torque motor and moves in response to signal to the torque motor. Operation is otherwise the same as a pressure pensated flow control valve.
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