1) 双泵并联供油回路 快速时两泵同时供油，工作进给时，高压小流量泵供油，从而实现了能量的合理使用。
4) 卸荷回路卸荷回路就是使油泵空载运转(输出功率很小)的回路。根据公式N=P Q 可知，如泵的输出流量Q。为零，或输出压力P 为零，都可使泵的输出功率N 为零而实现卸荷。当系统中各个执行元件暂时不工作时，若液压泵仍以溢流阀调定的压力值排流回油箱，则造成功率损失和油液发热，所以使泵空载运行可以节能，某些功率较大的液压泵，为保护电机也应卸荷情况下轻载启动。
Hydraulic transmission has many advantages and occupies an important position in the development of electromechanical integration in our country. However, in hydraulic transmission, energy loss (leakage loss, overflow power loss, throttle power loss, friction loss, etc.) is large, and transmission efficiency is low. These energy loss of hydraulic system will become heat, making the system temperature rise, and high temperature will affect the service life of hydraulic components and system reliability, so in the design of hydraulic transmission must consider to improve efficiency. This paper mainly discusses this problem from three aspects.
1. Reasonable selection of power components
This mainly refers to the selection of hydraulic pump and motor, which should be matched according to the working load diagram, especially the quantitative pump model should not be too large, so as to reduce energy consumption.
2. Reasonably arrange pipelines
In the layout of the pipeline, as far as possible to shorten the length of the pipeline, reduce the pipeline bending and section of the sudden change, the inner wall of the pipe to smooth, choose a reasonable pipe diameter, use a lower flow rate, can reduce the pressure loss of the system, improve the efficiency of the system.
3. Reasonable selection of hydraulic circuit
Proper circuit selection can obviously improve efficiency and reduce energy consumption.
1) when the parallel oil supply circuit of double pumps is fast, the two pumps supply oil at the same time. When the operation is fed, the high pressure and small flow pumps supply oil, so as to realize the reasonable use of energy.
2) the accumulator is matched with the small flow pump in the loop of the accumulator to meet the large flow demand of the hydraulic system. When the hydraulic cylinder stops moving, the pump will fill the accumulator with oil; When the hydraulic cylinder works, the pump and accumulator supply oil simultaneously.
3) volume speed regulation circuit volume speed regulation circuit does not throttle power loss and overflow power loss of throttle speed regulation circuit, with high efficiency.
4) unloading circuit According to the formula N=P Q, such as the output flow of the pump Q. Is zero, or the output pressure P is zero, can make the output power of the pump N is zero and achieve unloading. When each actuator in the system does not work temporarily, if the hydraulic pump is still discharged back to the oil tank with the pressure value set by the overflow valve, it will cause power loss and oil heating, so the no-load operation of the pump can save energy, some hydraulic pumps with large power should be started under light load in order to protect the motor.
5) the open pressure of the remote control balance valve in the remote control balance circuit has nothing to do with the back pressure of the hydraulic cylinder, generally only 30% ~ 40% of the system pressure. The piston downward balance valve is opened by the control oil, the back pressure disappears, and the system efficiency is higher.