A Brief Discussion on How to Reduce Power Loss in Hydraulic Systems

The power loss in the hydraulic system, on the one hand, causes energy loss, reducing the overall efficiency of the system. On the other hand, this lost part of the energy will be converted into heat energy, raising the temperature of the hydraulic oil, deteriorating the oil, and leading to malfunctions in the hydraulic equipment. Therefore, when designing a hydraulic system, in addition to meeting the usage requirements, it is also necessary to fully consider reducing the power loss of the system.

Firstly, from the perspective of the power source - the pump, considering the diverse working conditions of the actuator, sometimes the system requires a large flow rate and low pressure. Sometimes, a small flow rate and high pressure are needed. Therefore, it is advisable to choose a pressure-limiting variable pump, as the flow rate of this type of pump varies with the changes in system pressure. When the system pressure drops, the flow rate is relatively large, which can meet the rapid travel requirements of the actuator. When the system pressure increases, the flow rate decreases accordingly, which can meet the working stroke of the actuator. This way, not only can the working requirements of the actuator be met, but also the power consumption can be relatively reasonable.

Secondly, if the actuator has a requirement for speed regulation, then when choosing a speed regulation circuit, it is necessary to not only meet the speed regulation requirements but also minimize power loss as much as possible. The common speed control circuits mainly include: throttling speed control circuit, volumetric speed control circuit, and volumetric throttling speed control circuit. Among them, the power loss of the throttling speed control circuit is large, but the low-speed stability is good. The volumetric speed control circuit has neither overflow loss nor throttling loss, and is highly efficient, but its low-speed stability is poor. If both requirements are to be met simultaneously, a volumetric throttling speed control circuit composed of a differential pressure variable pump and a throttle valve can be adopted, and the pressure difference between the two ends of the throttle valve should be as small as possible to reduce pressure loss.

Thirdly, when hydraulic oil flows through various hydraulic valves, pressure loss and flow loss are inevitable. This part of the energy loss accounts for a large proportion of the total energy loss. Therefore, the rational selection of hydraulic devices and the adjustment of the pressure of pressure valves are also important aspects of reducing power loss. The flow valve should be selected based on the flow regulation range in the system and ensure that its minimum stable flow can meet the usage requirements. The pressure of the pressure valve should be as low as possible while ensuring the normal operation of the hydraulic equipment.

Fourth, choose hydraulic oil reasonably. When hydraulic oil flows in the pipeline, it will exhibit viscosity. If the viscosity is too high, it will generate a large internal friction force, causing the oil to heat up and increasing the resistance when the oil flows. When the viscosity is too low, it is prone to leakage, which will reduce the volumetric efficiency of the system. Therefore, oil with appropriate viscosity and good viscosity-temperature characteristics is generally selected. In addition, when the oil flows in the pipeline, there are also pressure losses along the way and local pressure losses. Therefore, when designing the pipeline, it is necessary to shorten the pipe as much as possible and reduce the number of bends at the same time.

The above considerations are merely from the perspective of reducing power loss in the hydraulic system. When specifically designing a hydraulic system, requirements from other aspects also need to be comprehensively considered.