液压论文翻译 急求

Question

Reduced pressure
In a system with only one pump, reduced pressure for one branch of the circuit can be obtained with a pressure-reducing valve. This circuit is typical for a welder, which requires high clamping force to be set by the relief valve and reduced force on the welding gun to be set by the pressure-reducing valve. Placing the check valve in parallel with the pressure-reducing valve allows free return flow when the weld cylinder retracts.
Remote control
Regulating pump pressure from a remote station can be accomplished by using small, pilot relief valves connected to the systems main pilot-operated relief valve. With the 3-way solenoid valve de-energized, system pressure is limited to 1,500 psi in this circuit. Energizing the 3-way solenoid valve permits venting the relief valve to either 1,000 psi or 500 psi, depending on the position of the 4-way valve, which is determined by the pilot signal it receives.
Two pressures
Pilot-operated relief valves provide two pressures for the mold-close cylinder and the injection cylinder of this plastic molding machine circuit. With the manual valve in neutral, the air-operated valves are actuated to extend the mold-close cylinder at a maximum pressure of 2,000 psi. Operating the manual valve to extend the injection cylinder vents the 400-psi relief to tank and vents the 2,000-psi relief at 400 psi. High-pressure fluid is held by the check valve.

Pressure-control valves are found in virtually every hydraulic system, and they assist in a variety of functions, from keeping system pressures safely below a desired upper limit to maintaining a set pressure in part of a circuit. Types include relief, reducing, sequence, counterbalance, and unloading. All of these are normally closed valves, except for reducing valves, which are normally open. For most of these valves, a restriction is necessary to produce the required pressure control. One exception is the externally piloted unloading valve, which depends on an external signal for its actuation.

Answer 1

减压
在只有一个泵的系统中，为一条支路减压可通过减压阀完成。对于焊工来说这是一个常见的回路，它需要很大的夹力用卸压阀来设置，焊枪上减小的力可通过减压阀来设置。将止回阀与减压阀并联可在焊接气缸缩回时提供一个自由回流回路。
遥控
从远程控制站调节泵压力可通过将小型液控溢流阀连接到系统的主液控卸压阀来实现。通过将三通电磁阀断电，该回路的系统压力将被限制在1,500 psi。为三通电磁阀通电可使卸压阀排气至1,000 psi或500 psi，具体哪个压力取决于4通阀的位置，而该位置又由它接收到的控制信号来决定。
两种压力
液控卸压阀为该塑料制模机电路的闭模气缸和压射气缸提供两种压力。当手动阀处于中间位置时，气动阀启动使闭模气缸的压力增至2,000 psi的最大压力。操作手动阀可将压射气缸向缸内排出400-psi的卸压压力，并在400 psi时产生2,000-psi的卸压压力。高压液被止回阀止住。

在几乎所有液压系统中都能找到压力控制阀，它们有助于实现各种功能，从将系统压力保持在所需的安全上限以下，到使一部分回路保持在一个设定的压力下。压力控制阀的类型包括卸压阀、减压阀、顺序阀、背压阀和卸载阀。除了减压阀是常通阀以外，上述所有类型均为常闭阀。大多数此类阀都需要一个限制以产生所需的压力控制。例外情况是外部控制卸载阀，它依靠外部信号来启动。