Anyone with basic mechanical knowledge knows that energy can be converted into various forms. Applying this knowledge to hydraulic systems best explains power loss. Power loss in a hydraulic system leads to energy loss, reducing overall system efficiency. Furthermore, this lost energy is converted into heat, raising the temperature of the hydraulic oil, causing oil deterioration, and ultimately leading to equipment malfunction. Therefore, when designing a hydraulic system, minimizing power loss should be a primary consideration, in addition to meeting operational requirements.
From the perspective of the power source-the pump-considering the diverse operating conditions of actuators, sometimes the system requires high flow rate and low pressure, while other times it requires low flow rate and high pressure. Therefore, a pressure-limiting variable displacement pump is preferable because its flow rate varies with system pressure. When system pressure decreases, the flow rate is higher, meeting the actuator's rapid stroke requirements. When system pressure increases, the flow rate decreases accordingly, meeting the actuator's working stroke requirements. This satisfies the actuator's operational requirements while ensuring reasonable power consumption.
Hydraulic oil inevitably experiences pressure and flow losses when flowing through various hydraulic valves, and these losses constitute a significant portion of the total energy loss. Therefore, selecting appropriate hydraulic components and adjusting the pressure of pressure valves are crucial for reducing power loss. Flow valves should be selected based on the system's flow regulation range, ensuring their minimum stable flow meets operational requirements. Pressure valves should be chosen at the lowest possible pressure, while still meeting the normal operating requirements of the hydraulic equipment.
If the actuator requires speed regulation, the speed control circuit must satisfy this requirement while minimizing power loss. Common speed control circuits include throttling speed control circuits, volumetric speed control circuits, and volumetric throttling speed control circuits. Throttling speed control circuits have high power loss but good low-speed stability. Volumetric speed control circuits have neither overflow nor throttling losses, offering high efficiency but poor low-speed stability. To simultaneously meet both requirements, a volumetric throttling speed control circuit composed of a differential pressure variable pump and a throttling valve can be used, minimizing the pressure difference across the throttling valve to reduce pressure loss.
Selecting appropriate hydraulic oil is also essential. When hydraulic oil flows in pipelines, it exhibits viscosity. Excessive viscosity generates significant internal friction, causing the oil to heat up and increasing flow resistance. Conversely, excessively low viscosity can lead to leaks and reduce system volumetric efficiency. Therefore, oils with suitable viscosity and good viscosity-temperature characteristics are generally selected. Furthermore, hydraulic oils experience pressure losses along the pipeline and localized pressure losses; therefore, pipeline design should aim to minimize pipe length and bends.
