在同一注塑机上,对采用异步电动机驱动定量泵、变转速异步电动机驱动定量泵、异步电动机驱动变量泵、变转速异步电动机驱动变量泵、交流伺服电动机驱动定量泵,5种电液控制方案加工同一制品的能量效率进行理论分析和试验对比。建立不同控制回路电动机和液压泵功率传输数学模型,绘制出能量特性曲线,分析对比注塑机工作在保压和冷却工况下,液压系统和电动机驱动系统功率消耗。研究结果证实,在部分负载和空载工况,异步电动机驱动定量泵系统存在大的溢流、节流损失,效率低;在此基础上引入变转速控制,包络系统所需的流量,可减少电动机功率消耗,提高系统效率,能量效率与异步电动机驱动变量泵相当;异步电动机驱动变量泵系统,可完全消除液压系统的溢流损耗,但电动机仍存在较大的空转损耗,在此基础上引入变转速控制,使电动机输出功率与液压负载相匹配,可进一步提高能量利用率26.5%;研究也表明,采用交流伺服电动机驱动的定量泵系统能量效率最高,较异步电动机驱动的定量泵系统节能88%,并且结构简单、动态性能好。
In the same injection molding machine,the theoretical analysis and experimental study on energy efficiency are done by using five different electro-hydraulic control strategies to process the same products,which five different control strategies are respectively induction motor driven constant pump,variable speed induction motor driven constant pump,induction motor driven variable displacement pump,variable speed induction motor driven variable displacement pump and AC servo motor driven constant pump.At first the power transmission mathematical models of motor and pump are established and the energy curves are drawn in the different control circuit.The power consumptions of the hydraulic system and the motor drive system are compared and analyzed,when the injection molding machine works in the packing and cooling conditions.The research results confirm that: In the part-load and no-load conditions the large overflow and throttle losses and low efficiency exist in induction motor driven constant pump system.On this basis variable speed control is introduced and implemented by enveloping the system required flow,so the motor power consumption is reduced and the efficiency is improved and the energy efficiency nearly equals by comparing with the induction motor driven variable displacement pump system.In the induction motor driven variable displacement pump system,the overflow losses are completely eliminated,however the big motor idling loss still exits.On this basis variable speed control is introduced to the motor output power and the hydraulic load matching,and to further improve the energy efficiency of 26.5%.The research also shows that the energy efficiency of the AC servo motor driven constant pump system is the highest,and can save energy 88% by comparing with induction motor driven constant pump,and the system has simple structure and good dynamic performance.