INCREASING AUTOMOBILE-ENGINE THERMAL EFFICIENCY

The efficiency of the automobile engine, as operated on the Otto cycle, is thought by the author to be too low, and he therefore suggests a method of improving it. He considers the various losses by which heat is dissipated in internal-combustion engines and finds that the best opportunity for increasing thermal efficiency is by an increased expansion of the charge. The author suggests that this expansion be carried 50 per cent further than is ordinarily done.

In order to obtain higher efficiency at part load, the suggestion is made that instead of throttling the mixture, the admission valves be closed earlier. In case the expansion is 50 per cent longer than the induction stroke and the cut-off takes place earlier as the load becomes lighter, it will be necessary to vary the fuel opening inversely with the air induced. It is suggested that the fuel valve and cut-off lever be connected together and operated by the accelerator pedal or hand lever on the steering wheel.