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Research on an electrically controlled system which can stably maintain a constant engine speed, while carrying out choke operations using a choke valve when starting the engine, was carried out with the objective of constructing an electrically controlled auto choke system for a general purpose engine that can control both choke mechanism and engine speed with a single motor. Research was also carried out on a mechanism that could drive both the throttle and choke valves with a single motor. First, the throttle valve was fixed in the fully open position and the relationship between the choke valve mechanism and engine speed was analyzed. The relationship between the opening angle of the choke valve and engine speed could be formulated by second order transfer function. However, it became clear that transfer function parameters drastically changed depending on ambient temperature and plug seat temperature.

The purpose of this study was to develop a simple optimization method for use in designing vibration insulators. With this method, stiffness, location and inclination of each insulator are used as design parameters. A performance index consisting of vehicle modal parameters expressed as eigenvalues and eigenvectors has been constructed to evaluate low-frequency idle/shake performance and higher frequency vibration performance involving road/engine inputs. Using this performance index and the sensitivity of the modal parameters, a designer can easily find a suitable direction for optimizing mount performance and thereby obtain a stable solution. The new method was employed to optimize an engine mount system. Experimental data obtained on the system validated the accuracy of the calculated results and showed an improvement in idle/shake performance. This method is a useful tool in designing optimum vibration insulators.