液压压差损耗能量回收节能机理及工作特性研究

The main energy loss which leads to the low efficiency of hydraulic system is the throttle loss and overflow loss. The traditional energy saving technology of hydraulic system is based on the flow matching. Because the minimum throttle flow is the required flow of the actuator and the overflow flow is random, to reduce the hydraulic energy loss through reducing the flow has a certain limitation, especially in high-pressure hydraulic systems, one pump for multi-actuators systems and hydraulic systems with negative loads. What's more, reducing the overflow loss is considered to be even impossible.. This project aims to explore the working principle and realization method of overflow energy loss and throttle energy loss regeneration and utilization technology for hydraulic system. The main innovations and tasks of this project are as follows: (1) The energy recovery unit is used as a pressure difference compensator for the throttle orifice to achieve a smaller pressure difference which is sufficient for the adjustment of the flow rate. The energy which is consumed on the pressure compensator in the traditional conditions is recovered by the energy regeneration unit. (2) A new hydraulic drive method was proposed to recovery the overflow loss through an energy recovery unit which is connected to the outlet of a relief valve to improve the outlet pressure. (3) The influence of the energy recovery unit on the working characteristics of the relief valve and throttle valve is discussed. The new control method for the energy recovery unit of variable pressure drop is explored to gain better static and dynamic characteristics for relief valve and throttle valve. Basic applications of the proposed method is studied. This project will explore a new energy saving system with negligible energy loss for hydraulic system and offer a design basis for the next generation energy saving hydraulic system.

导致液压系统效率低下的主要损耗为节流损耗和溢流损耗。考虑到节流流量的最小值为目标流量不能任意降低和溢流流量具有随机性的特点，通过降低流量的方式在液压节能上具有一定的局限性，尤其在高压化、单泵多执行器或者具有负值负载等存在阀口压差较大的液压系统。而降低溢流阀口压差更是被认为难以攻克的技术瓶颈。.项目从降低压差的途径实现液压节能。主要创新和研究内容为：1）将能量回收单元作为节流阀口的压差补偿器，使得节流阀口压差仅为一个用于保证工作特性所需的较小压差，并将传统消耗在压力补偿器的节流损耗进行回收；2）将能量回收单元和溢流阀出油口相连，通过能量回收单元主动控制溢流阀口压差仅为保证工作性能所需的最小压差并回收多余的溢流损耗；3）探讨能量回收单元对工作特性的影响规律，探索能量回收单元的变压差主动控制方法，研究新方法的节能机理和操控特性。本项目为新一代节能液压系统提供一种新的思路和设计依据。

导致液压系统效率低下的主要损耗为节流损耗和溢流损耗。考虑到节流流量的最小值为目标流量不能任意降低和溢流流量具有随机性的特点，通过降低流量的方式在液压节能上具有一定的局限性，尤其在高压化、单泵多执行器或者具有负值负载等存在阀口压差较大的液压系统。而降低溢流阀口压差更是被认为难以攻克的技术瓶颈。.项目从降低压差的途径实现液压节能。主要创新和研究内容为：1）将能量回收单元作为节流阀口的压差补偿器，使得节流阀口压差仅为一个用于保证工作特性所需的较小压差，并将传统消耗在压力补偿器的节流损耗进行回收；2）将能量回收单元和溢流阀出油口相连，通过能量回收单元主动控制溢流阀口压差仅为保证工作性能所需的最小压差并回收多余的溢流损耗；3）探讨能量回收单元对工作特性的影响规律，探索能量回收单元的变压差主动控制方法，研究新方法的节能机理和操控特性。.研究结果表明，将能量回收单元应用于溢流损耗能量回收，不仅不会影响溢流阀的工作特性，还能减低调压偏差，且背压压力越高，调压偏差越小，当背压为18 MPa时，调压偏差仅为2.5%。当采用液压式能量回收时，蓄能器能量回收效率最低为61.2%；当采用电气式能量回收时，系统的最大效率为79%，最小效率为15%。系统损耗的功率降低了67%，节能效果明显。将所提出的压差损耗能量回收方案应用于某3 t电动叉车的势能回收系统，结果表明最小目标压差不能低于0.8 MPa时系统具有较好的操控性能，系统能量回收效率随马达转速的增大呈现先增大后减小的趋势，整体效率较高，系统举升时效率为42%，下降时能量回收效率为51%。.本项目为新一代节能液压系统提供一种新的思路和设计依据。

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