洗衣机性能测试恒温水系统设计

The design of constant temperature water system for washing machines performance testing

本文介绍了为家用洗衣机性能测试实验室而设计的恒温水供水系统。该系统可为六工位家用电动洗衣机提供5℃~60℃、误差不超过±0.3℃的恒温水。供水压力0.24MPa、误差不超过±0.02MPa。电热水器及风冷冷水机组联合使用控制水温。在恒温水箱和冷水机组之间设置板式换热器,保证恒温水箱温度的精确恒定。为了保证水系统各处温度相同的同时避免供水水泵的频繁启停,冷温水与热水系统分别采用独立自循环的方式。变频供水水泵不仅可以调节水流量大小,而且可以精确控制供水水压。依据GB/T 5750.4-2006与GB/T 4288-2008标准对水质进行严格软化处理,保证洗衣机用水对其性能测试结果无影响。联合使用PLC和PID,测试精度较传统恒温水系统更高。

The article described a constant temperature water system which is used in the performance testing laboratory for electric washing machines. The system can provide with constant temperature water which ranges from 5℃ to 60℃ for six washing machines. The temperature accuracy is within ±0.3℃.The pressure of water supplied by the system is 0.24 MPa. And the pressure accuracy is within ± 0.02 MPa.The electric water heater and air cool chillers are used to control temperature of the water. Plate heat exchanger is used between the thermostatic water tanks and the air cool chiller to ensure the accuracy control for the temperature of thermostatic water tank. In order to ensure the same temperature throughout the water system and avoid the water-supply pump to start or to stop frequently, the way of independent self-loop was used in water supply system. Not only the variable frequency pump changed the quantity of water flow, but also accurately controlled the pressure of the water supplied. The water was strictly softened based on GB/T 5750.4-2006 and GB/T 4288-2008 which ensured the washing machine water had no effect on its performance test results. Compared with the traditional system, jointing use of PLC and PID makes this system achieve higher testing precision.