Multi-stage compression ignition engine start
A powertrain includes a diesel compression engine and an electric machine operatively coupled thereto and effective to rotate the engine during engine cranking. Cold engine cranking is accomplished in a staged manner including a first stage wherein the engine is cranked to a first speed below the resonant speed of the coupled engine and electric machine combination for a first duration and thereafter cranked to a second speed above the resonant speed for a second duration. Transition out of cranking at the first and second speeds is accomplished when relative combustion stability is demonstrated. Cranking at the first or second speed is aborted when excessive crank times or if low battery voltages are observed. A third stage is included wherein the engine is cranked to a third speed below the engine idle speed. Transition out of cranking at the third speed is accomplished when relative combustion stability is demonstrated, whereafter normal engine control takes over.
General Motors Corporation
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inventional additional inventional
Gregory A. William R. Jy-Jen F. Xuefeng T. Todd M.
Hubbard Cawthorne Sah Tao Steinmetz