冰箱直线压缩机运行不稳定的实验研究

本文进行了直线压缩机冰箱系统的制冷实验,分析了直线压缩机运行的不稳定特性。结果表明:冰箱制冷过程中直线压缩机定频运行,会出现三种不同的不稳定状态:启动调节不稳定、外部扰动不稳定和电磁阀调节不稳定。启动过程中,供电参数的调节以及吸排气压力的变化引起的不稳定状态,随着电参数保持不变和吸排气压力趋于稳定,启动过程的不稳定现象也逐渐消失。当供电参数和制冷工况保持稳定时,制冷系统的随机扰动也会使直线压缩机产生一定的不稳定振荡,行程最大振幅约0.3 mm,电流和输入功的最大波动约为平均值的10%,直线压缩机对外部扰动具有自修复性。电磁阀调节过程对直线压缩机的稳定性影响较大,行程最大振幅约2.2 mm,压缩机存在极大的撞缸可能性。因此非常有必要结合制冷系统的运行工况,进行直线压缩机本体结构和控制系统的优化设计,保证直线压缩机在冰箱调节过程中安全可靠的运行。

Experimental Investigation on Instability of Linear Compressor in Refrigerator

The instability of a linear compressor is studied by an experiment on a developed linear compressor in a refrigerator. The experimental results show that there are three types of unstable phenomena: the start-up process, external disturbance process, and solenoid valve adjustment process. During the start-up process, an unstable status is caused by the adjustment of the supply power and changes in the refrigerant suction/discharge pressure. This finally settles down as the supply power and suction/discharge pressure are unchanged. Some external disturbance of the refrigeration system causes an unstable oscillation with a fluctuation of about 0.3 mm of the piston displacement. Accordingly, the current and the input power fluctuate at about 10% of their average values. This oscillation gradually becomes stable as there is no more disturbances. The solenoid valve adjustment process has a great influence on the stability of a linear compressor. In this experiment, the maximal fluctuation amplitude of the displacement is about 2.2 mm, and the piston is apt to strike the cylinder. Therefore, the design optimization for a linear compressor structure, and a control strategy based on the change characteristics of the working conditions, is necessary to ensure operational reliability and high efficiency.