Method and system for kinetic energy recovery in a hybrid powertrain during engine shutdown

A method for recovering energy from an engine in a hybrid powertrain including at least one motor/generator (“MG”), comprising:

• detecting that (1) engine torque and torque associated with the at least one MG is reduced to zero or near zero and (2) the transmission is in a neutral gear;
• operating the at least one MG in a generator mode, in response to the detecting, to recover kinetic energy from the engine by loading the engine through a clutch;
• disengaging the clutch to decouple the at least one MG from the engine;
• shifting the transmission into gear in response to a speed of the at least one MG reaching a target speed;
• and
• propelling a vehicle using power from the at least one MG after shifting the transmission into gear.

A hybrid powertrain system, comprising:

• an engine;
• at least one motor/generator (“MG”);
• a transmission coupled to the at least one MG;
• a first clutch coupled to the engine and the at least one MG;
• a second clutch coupled between the at least one MG and a final drive;
• and
• a controller operatively coupled to the engine, the at least one MG, the first clutch, and the second clutch, the controller including a processor and a memory including instructions that when executed by the processor, cause the controller to:
• open the second clutch in response to engine torque and torque associated with the at least one MG being reduced to zero or near zero,
• operate the at least one MG in a generator mode to recover kinetic energy from the engine by loading the engine through the first clutch,
• disengage the first clutch to decouple the at least one MG from the engine,
• engage the at least one MG with the transmission in response to the at least one MG being decoupled from the engine, and
• close the second clutch in response to a speed of the at least one MG reaching a target speed.

A method for recovering energy from an engine in a hybrid powertrain including at least one motor/generator (“MG”), comprising:

• opening a second clutch coupled between the at least one MG and a final drive in response to engine torque and torque associated with the at least one MG being reduced to zero or near zero;
• operating the at least one MG in a generator mode to recover kinetic energy from the engine by loading the engine through a first clutch coupled to the engine and the at least one MG;
• disengaging the first clutch to decouple the at least one MG from the engine;
• engaging the at least one MG with a transmission coupled to the at least one MG in response to the at least one MG being decoupled from the engine;
• and
• closing the second clutch in response to a speed of the at least one MG reaching a target speed.

A hybrid powertrain system, comprising:

• an engine;
• at least one motor/generator (“MG”);
• a clutch coupled to the engine and the at least one MG;
• a transmission coupled to the at least one MG;
• and
• a controller operatively coupled to the engine, the at least one MG, the clutch, and the transmission, the controller including a processor and a memory including instructions that when executed by the processor, cause the controller to:
• operate, in response to (1) engine torque and torque associated with the at least one MG being reduced to zero or near zero and (2) the transmission being shifted to a neutral gear, the at least one MG in a generator mode to recover kinetic energy from the engine by loading the engine through the clutch,
• disengage the clutch to decouple the at least one MG from the engine, and
• shift the transmission into gear in response to a speed of the at least one MG reaching a target speed,
• wherein a load applied on the engine that results from operating the at least one MG in the generator mode causes the engine to reach a zero or near-zero speed condition more quickly than when the engine is allowed to coast to the zero or near-zero speed condition.

A hybrid powertrain system, comprising:

• an engine;
• at least one motor/generator (“MG”);
• a clutch coupled to the engine and the at least one MG;
• a transmission coupled to the at least one MG;
• and
• a controller operatively coupled to the engine, the at least one MG, the clutch, and the transmission, the controller including a processor and a memory including instructions that when executed by the processor, cause the controller to:
• operate, in response to (1) engine torque and torque associated with the at least one MG being reduced to zero or near zero and (2) the transmission being shifted to a neutral gear, the at least one MG in a generator mode to recover kinetic energy from the engine by loading the engine through the clutch,
• disengage the clutch to decouple the at least one MG from the engine,
• shift the transmission into gear in response to a speed of the at least one MG reaching a target speed, and
• responsive to determining that an additional torque is required, restart the engine to provide the additional torque.