Hybrid powertrain system including an internal combustion engine and a stirling engine

1. An exhaust aftertreatment system for treating an exhaust gas feedstream of an internal combustion engine, including:

a catalytic converter;

a fluidic circuit comprising a working fluid heat exchanger inserted into the exhaust gas feedstream upstream of the catalytic converter, the working fluid heat exchanger including a first heat transfer surface in fluid contact with the exhaust gas feedstream and a second heat transfer surface, wherein the fluidic circuit contains a working fluid in contact with the second heat transfer surface;

a Stirling engine comprising a closed-cycle regenerating heat engine including a hot side, a cold side and an output member, the hot side fluidly connected to the fluidic circuit containing the working fluid and the output member mechanically coupled to an electric motor/generator;

the Stirling engine configured to transform thermal energy from the working fluid heat exchanger to mechanical power transferable to the electric motor/generator to generate electric power;

the Stirling engine configured to transform mechanical power from the electric motor/generator to thermal energy transferable to the working fluid heat exchanger; and

an auxiliary air blower configured to pump ambient air into the exhaust gas feedstream upstream of the working fluid heat exchanger and the catalytic converter, the working fluid heat exchanger configured to transfer thermal energy to the ambient air pumped into the exhaust gas feedstream prior to flowing through the catalytic converter.

2. The exhaust aftertreatment system of claim 1 , wherein the Stirling engine is configured to operate as a heat pump to transform mechanical power from the electric motor/generator to thermal energy in the working fluid that is transferable to the working fluid heat exchanger.

3. The exhaust aftertreatment system of claim 1 , further comprising a second heat exchanger thermally connected to the cold side of the Stirling engine.

4. The exhaust aftertreatment system of claim 3 , further comprising a coolant circuit of the internal combustion engine fluidly connected to the second heat exchanger.

5. The exhaust aftertreatment system of claim 1 , further comprising an inverter module electrically connected to an electric power bus, said inverter module electrically connected to the electric motor/generator device.

6. The exhaust aftertreatment system of claim 1 , further comprising a catalytic washcoat in fluid contact with the exhaust gas feedstream disposed on the first heat transfer surface.

7. The exhaust aftertreatment system of claim 6 , wherein the working fluid heat exchanger comprises a plate-type heat exchanger.

8. An exhaust aftertreatment system for an internal combustion engine, comprising:

a fluidic circuit comprising a working fluid heat exchanger inserted into an exhaust gas feedstream upstream of an exhaust aftertreatment device, the working fluid heat exchanger including a first heat transfer surface in fluid contact with the exhaust gas feedstream and a second heat transfer surface, wherein the fluidic circuit contains a working fluid in contact with the second heat transfer surface;

a Stirling engine comprising a closed-cycle regenerating heat engine including a hot side, a cold side and an output member, the hot side fluidly connected to the fluidic circuit containing the working fluid, the cold side thermally coupled to an engine coolant circuit, and the output member mechanically coupled to an electric motor/generator;

the Stirling engine configured to transform thermal energy from the working fluid heat exchanger to mechanical power transferable to the electric motor/generator to generate electric power;

the Stirling engine configured to transform mechanical power from the electric motor/generator to thermal energy transferable to the exhaust aftertreatment device via the working fluid heat exchanger; and

an auxiliary air blower configured to pump ambient air into the exhaust gas feedstream upstream of the working fluid heat exchanger and the exhaust aftertreatment device, the working fluid heat exchanger configured to transfer thermal energy to the ambient air pumped into the exhaust gas feedstream prior to flowing through the exhaust aftertreatment device.

9. The exhaust aftertreatment system of claim 8 , further comprising a catalytic washcoat disposed on the first heat transfer surface of the working fluid heat exchanger.

10. A system for transferring heat energy in a hybrid powertrain system including an internal combustion engine, including:

a Stirling engine comprising a closed-cycle regenerating heat engine including a hot side, a cold side and an output member, the hot side fluidly connected to a fluidic circuit containing a working fluid, the cold side thermally coupled to a coolant circuit, and the output member mechanically coupled to an electric motor/generator electrically connected to an inverter module electrically connected to an electric power bus;

a catalytic converter;

the fluidic circuit including a first working fluid heat exchanger inserted into an exhaust gas feedstream upstream of the catalytic converter, the working fluid heat exchanger including a first heat transfer surface thermally connected to the exhaust gas feedstream and a second heat transfer surface in thermal contact with the working fluid;

the fluidic circuit further including a plurality of additional working fluid heat exchangers each including a first heat transfer surface thermally connected to one of a plurality of heatable elements associated with the hybrid powertrain system;

the Stirling engine configured to transform thermal energy transferred from the exhaust gas feedstream and the plurality of heatable elements associated with the hybrid powertrain system to mechanical power transferable to the electric motor/generator to generate electric power;

the Stirling engine configured to transform mechanical power from the electric motor/generator to thermal energy transferable to the first working fluid heat exchanger and the plurality of additional working fluid heat exchangers; and

an auxiliary air blower configured to pump ambient air into the exhaust gas feedstream upstream of the first working fluid heat exchanger and the catalytic converter, the first working fluid heat exchanger configured to transfer thermal energy to the ambient air pumped into the exhaust gas feedstream prior to flowing through the catalytic converter.

11. The system of claim 10 , wherein the fluidic circuit further comprises a plurality of flow control valves, each flow control valve configured to control flow of the working fluid to a respective one of the first and the plurality of additional working fluid heat exchangers.

12. The system of claim 10 , further comprising a catalytic washcoat in fluid contact with the exhaust gas feedstream disposed on the first heat transfer surface.

13. The system of claim 10 , wherein one of the heatable elements comprises transmission fluid contained in a transmission fluid sump.

14. The system of claim 10 , wherein one of the heatable elements comprises engine oil contained in an engine oil sump.

15. The system of claim 11 , wherein one of the heatable elements comprises engine coolant contained in a coolant reservoir.

16. The system of claim 12 , wherein one of the heatable elements comprises recirculated exhaust gas.