Patent ID: 7748481

Claim:
A hybrid powertrain for a vehicle comprising: an internal combustion engine sufficiently configured for operation in a homogeneous charge compression ignition mode of operation, wherein said internal combustion engine includes; a variable volume chamber for compressing a mixture of at least intake air and fuel; a piston at least partially defining said variable volume chamber; a fuel injector sufficiently configured to inject said fuel directly into said variable volume chamber for combustion with said intake air; an ignition device in direct communication with said variable volume chamber for initiating combustion of said mixture; a controller operatively connected to said fuel injector and sufficiently configured to effect said homogeneous charge compression ignition mode of operation; a first motor and an energy storage device in hybrid combination with said internal combustion engine and sufficiently configured to selectively effect propulsion of the vehicle at low speeds exclusive of operation of said internal combustion engine; and a transmission operatively connected to said internal combustion engine and said first motor, and arranged to optimize the homogeneous charge compression ignition mode of operation of the internal combustion engine for a given engine power level by at least each of a) maintaining a rotational speed of the internal combustion engine within a predetermined operating range and b) varying the rotational speed.