Design and fabrication of a micro Wankel engine using MEMS technology

Abstract

Hydrocarbon fuels have much higher energy to weight ratios than batteries. A research project is being carried out at the University of Birmingham to develop microengines to replace batteries. The project will be carried out into two stages. In the first stage a cryogenic CO 2 engine is to be produced, followed in the second stage by the development of a micro combustion engine. This paper presents the first stage work to develop a micro Wankel engine from the design to the fabrication of a CO 2 microengine. The design of the micro Wankel engine is based on its macro counterpart, but in the CO 2 engine the housing curve has been modified to eliminate the compression stage of the Otto cycle. Finite-element analysis has been carried out during the design for both cryogenic and combustion engines to ensure that the engines can withstand the pressure released from their respective energy sources, and that deformation will not cause leakage. An advanced UV-lithography process has been developed, which can produce ultra thickness and high aspect ratio engine components. The precision and geometry of the engine components satisfy very strict design requirements. At present, a CO 2 engine has been successfully fabricated and is under test.