| 摘要 |
A Recuperative Cycle tow-stroke internal combustion engine having an expander cylinder with an open combustion chamber in its working end and a separate compressor for injecting a compressed air charge into the chamber obtains improved Carnot efficiency by the containment of all its working components in a new and novel cylinder head. This head captures thermal energy normally thrown away in engine exhaust and transfers it advantageously back into the working cycle. The result, long sought by others, has been achieved by incorporating compactly within the head an internal exhaust heat recuperator or heat exchanger closely coupled with a combustion chamber open to the expansion cylinder. A recuperator-protecting valve isolates the recuperator from hot combustion gases until they have been cooled by full piston expansion and a catalytic convertor may be placed in an optimum temperature position within the recuperator chamber. A prototype has demonstrated that the recuperation can reduce exhaust temperature by as much as 600° Rankine below that attainable in an equivalent Otto Cycle engine. The displacement ratio between compressor cylinder and expander cylinder may be optimized during design, such as with a 6:1 compression ratio and a 15:1 expansion ratio, and this feature in combination with the open combustion chamber and the ability to operate the compressor with a phase lead over the expander enables the efficiency to be as much as one-third higher than in an Otto Cycle engine. Recuperators of both common-duct and separated-duct design are described, the latter embodiment being preferred as it provides cleaner burning and a reduction in the number of valves necessary to control gas flow.
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