Multi-stage compression ignition engine start

Method for starting a compression ignition engine operatively coupled to an electric machine, comprising:

• cranking the engine with the electric machine up to a first speed substantially below a natural resonant speed of the operatively coupled engine and electric machine combination for a first duration;
• and
• thereafter cranking the engine with the electric machine up to a second speed substantially above the natural resonant speed of the operatively coupled engine and motor combination;
• wherein said first duration terminates when the engine speed exceeds a predetermined speed above said first speed for a predetermined time under engine combustion power.

Method for starting a compression ignition engine operatively coupled to an electric machine, comprising:

• cranking the engine with the electric machine up to a first speed substantially below a natural resonant speed of the operatively coupled engine and electric machine combination for a first duration;
• and
• thereafter cranking the engine with the electric machine up to a second speed substantially above the natural resonant speed of the operatively coupled engine and motor combination;
• wherein the engine is cranked with the electric machine up to the second speed for a second duration, and thereafter cranking the engine with the electric machine up to a third speed slightly below engine idle speed for a third duration.

Method for starting a compression ignition engine operatively coupled to an electric machine, comprising:

• cranking the engine with the electric machine up to a first speed substantially below a natural resonant speed of the operatively coupled engine and electric machine combination for a first duration;
• and
• thereafter cranking the engine with the electric machine up to a second speed substantially above the natural resonant speed of the operatively coupled engine and motor combination;
• wherein cranking at either of the first and second speeds is aborted if cranking at the respective speed continues for a predetermined excessive time.