| As we all know, piston is one of the key parts of engine, whose work situation has adirect influence on engine’s overall performance. So the design and improvement of pistonhave received more and more attentions. The piston’s loads mainly come from two sides:mechanical and thermal, so it is important to analyze the failure mechanisms of pistonunder different load.In order to research the piston failure problems under the thermal load alone, andsimulate the transient temperature field of piston in engine, this paper designs a thermalfatigue laboratory which uses high power laser as the heat source, whose beam istranslated into three concentric rings to heat the top surface of piston with theindependently adjustable power. The cooling system is divided into compressed aircooling and water cooling, to cool the top and skirt surface of piston respectively. The keyequipments of air cooling system are air compressor and end pipe, and for the watercooling system, they are water pump and pipes. Through the cooperation of heating andcooling, the HCF and LCF can realize in piston, so the thermal fatigue strength can beobtained. The monitoring and control system is built based on Kingview, which uses thecomputer as the upper layer, utilizes RS-485for the communication serial port in themiddle layer, and takes PLC and SCM as the bottom layer controllers. The cooperationbetween heating and cooling is accomplished by the control system. The measurementsystem monitors the temperature field and cracks of test object in real time, which iscomposed of infrared thermometer, thermocouple and CCD camera.The laboratory is also applicable to the thermal load analysis of combustion chamberparts, such as cylinder head, cylinder liner and valve. With the different thermal fatiguetest criterion, the output power and operation time of the heating and cooling systemshould be changed by the control system in PC, so the thermal fatigue strength of differentparts can be evaluated. |
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