The Development and Evaluation of an Electronic Indicated Horsepower Meter 690181

A complete electronic system for accurately and continuously measuring the indicated power of a reciprocating engine is presented in this paper. This includes an analog switching technique for separating the pumping power of a four-stroke cycle engine from the net cycle output.
An analysis and evaluation of the individual components and circuits composing the complete instrument is made to determine the accuracy and limitations of the system and techniques used. The measurement of cylinder pressure, the weakest link in the entire system, is analyzed in detail to determine the pressure measuring requirements for the measurement of indicated power and the ability of some commercially available analog pressure transducers to meet these requirements.
Data from a single cylinder, CFR, spark ignition engine are presented and used both as a means of evaluating the instrument and pressure transducers as well as to supply information on engine friction.


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