Research development of a portable micro power generator based on MEMS heat engine

成功地演示了MEMS二冲程热机的氢燃料燃烧。该MEMS热机可用于集成微电磁发电机的便携式微电源。燃烧室体积为0.5mm^3，发动机理论压缩比为1.6。SOI本体微机械加工用于制造发动机部件，即发动机部件。、活塞、气缸、弹性弹簧、机匣和燃烧室。活塞由弹性弹簧支撑，弹簧的排斥力驱动燃烧产生的往复运动。采用共晶粘接法将活塞与气缸进行粘接，完成发动机装配。燃烧采用氢氧预混合燃料。燃料的预混合由精密质量流量计控制。燃烧的火花点火系统由pt线塞和外置电容组成。用高速CMOS相机和激光多普勒振动仪测量活塞的位移。燃烧压力由集成在燃烧装置中的压阻式压力传感器测量。化学计量燃烧时实验燃烧压力为150kPa。在实验过程中没有观察到淬火的迹象。活塞的位移为0.2mm，这相当于20mW的发电量。获得了世界最小燃烧室的发动机动力循环压力-体积图，成功地展示了世界最小燃烧室的微燃烧，证实了微发电系统的良好前景。

Hydrogen fuel combustion of MEMS two-stroke heat engine was successfully demonstrated. The MEMS heat engine can be used for a portable micro power generator with integrated micro electro magnetic generator. Volume of combustion chamber was 0.5mm^3 and theoretical engine compression ratio was 1.6. SOI bulk micromachining was used to fabricate engine components, ie., piston, cylinder, elastic spring, casing and the combustion chamber. The piston was supported by the elastic spring and the repulsion force of the spring is used to drive a reciprocal motion exerted by the combustion. The piston and the cylinder were boned by the eutectic bonding method to complete engine assembly.Hydrogen-oxygen pre-mixed fuel was used for the combustion. Pre-mixture of the fuel was controlled by precise mass flow meters. Spark ignition system of the combustion was composed of Pt-wire plugs and an external capacitor. Displacement of the piston was measured by a high-speed CMOS camera and a laser Doppler vibration-meter. Combustion pressure was measured by a piezoresistive pressure sensor integrated into the combustion rig. Experimental combustion pressure was 150kPa at stoichiometric combustion. No evidence of quenching was observed during the experiment. The displacement of the piston was 0.2mm, and this is equivalent to 20mW of power generation. The pressure-volume diagram of engine power cycle was obtained for the world-smallest combustion chamber: Thus, the micro combustion in the world-smallest chamber was successfully demonstrated, and good prospect for micro power generation system was confirmed.