Methods and systems for hybrid vehicle waste heat recovery

Patent metadata

Field	Value
Publication number	US-9587546-B2
Application number	US-201314044506-A
Country	US
Kind code	B2
Filing date	Oct 2, 2013
Priority date	Oct 2, 2013
Publication date	Mar 7, 2017
Grant date	Mar 7, 2017

Abstract

Systems and methods for operating an engine that includes an exhaust gas heat recovery system are described. The system may selectively or contemporaneously supply energy from engine exhaust gas to generate electricity or warm the engine. In one example, exhaust gas energy raises a temperature of a heat transfer medium and the heat transfer medium is routed to an engine coolant heat exchanger or an expander via a bypass valve.

First claim

The invention claimed is:

1. An engine system, comprising:
an engine including an evaporator positioned along an exhaust system;
an expander in fluidic communication with the evaporator;
a condenser in fluidic communication with the evaporator;
an engine coolant heat exchanger including an inlet in thermal communication with the condenser, the engine coolant heat exchanger including an outlet that is in fluidic communication with an inlet of the evaporator, the engine coolant heat exchanger positioned between a circuit including a working fluid and an engine coolant circuit;
a pump including an inlet;
an exhaust gas heat recovery system valve in fluidic communication with an outlet of the evaporator, an inlet of the expander, and the inlet of the pump; and
a controller including executable instructions stored in non-transitory memory to:
adjust a position of the exhaust gas heat recovery system valve to supply working fluid from the evaporator solely to the inlet of the expander to rotate a generator to produce electrical energy in response to a first condition comprising a state of battery charge being less than a threshold charge; and
adjust the position of the exhaust gas heat recovery system valve to supply working fluid from the evaporator solely to the inlet of the expander to rotate the generator to produce electrical energy in response to a second condition comprising the state of battery charge being greater than the threshold charge and an engine coolant temperature being greater than a first threshold temperature.

2. The engine system of claim 1 , where an inlet of the exhaust gas heat recovery system valve is in direct fluidic communication with the outlet of the evaporator.

3. The engine system of claim 1 , further comprising a passenger cabin heater core positioned between the outlet and the inlet of the evaporator.

4. A method for operating an engine, comprising:
operating an engine;
extracting engine exhaust gas heat via an evaporator and converting the engine exhaust gas heat to electrical energy via an expander in a first operating mode;
extracting engine exhaust gas heat to a working fluid comprising carbon hydrides via the evaporator and transferring the engine exhaust gas heat from the working fluid to engine coolant via an engine coolant heat exchanger in a second operating mode;
adjusting a position of an exhaust gas heat recovery system valve to operate in the first operating mode in response to a battery state of charge and to direct working fluid solely to the expander in response to the battery state of charge being less than a threshold and regardless of an engine coolant temperature, the expander rotating a generator to produce electrical energy in the first operating mode; and
adjusting the position of the exhaust gas heat recovery system valve to operate in the second operating mode in response to the battery state of charge being greater than the threshold and the engine coolant temperature being less than a first threshold temperatures;
where the first operating mode is activated in response to the battery state of charge being greater than the threshold and the engine coolant temperature being greater than a second threshold temperature, the second threshold temperature greater than the first threshold temperature.

5. The method of claim 4 , further comprising flowing the working fluid from the exhaust gas heat recovery system valve to the expander while flowing the working fluid from the exhaust gas heat recovery system valve to a pump bypassing the expander in response to an engine operating condition.

6. The method of claim 4 , further comprising adjusting the position of the exhaust gas heat recovery system valve to switch between the first operating mode and the second operating mode.

7. The method of claim 4 , further comprising adjusting the position of the exhaust gas heat recovery system valve in response to a temperature of a heat transfer medium exiting the evaporator to switch between the first operating mode and the second operating mode; and
wherein the second operating mode is further activated in response to the battery state of charge being greater than the threshold and the engine coolant temperature being between the first and second threshold temperatures.

8. The method of claim 7 , further comprising increasing a temperature of an axle during the second operating mode; and
wherein, in the second operating mode, working fluid is additionally directed to the expander in response to the engine coolant temperature not increasing.

9. The method of claim 8 , further comprising preheating the heat transfer medium in the first operating mode before heating the heat transfer medium via engine exhaust gas; and
wherein, in the second operating mode, working fluid is solely directed to the engine coolant heat exchanger in response to the engine coolant temperature increasing.

10. A method for operating an engine, comprising:
operating an engine; and
contemporaneously increasing an engine coolant temperature and electrical output of a generator via adjusting an exhaust gas heat recovery system valve that routes a heat transfer medium from an evaporator to an expander and an engine coolant heat exchanger responsive to vehicle operating conditions including a battery state of charge being greater than a threshold and the engine coolant temperature being above a first threshold temperature and not increasing during a first operating mode, the expander rotating the generator to provide electrical energy in the first operating mode.

11. The method of claim 10 , further comprising routing the heat transfer medium from the evaporator solely to the expander via the exhaust gas heat recovery system valve in a second operating mode in response to the battery state of charge being less than the threshold.

12. The method of claim 11 , further comprising routing the heat transfer medium from the evaporator solely to the engine coolant heat exchanger via the exhaust gas heat recovery system valve in a third operating mode in response to the battery state of charge being greater than the threshold and the engine coolant temperature being below a second threshold temperature and increasing, the second threshold temperature greater than the first threshold temperature.

13. The method of claim 10 , further comprising adjusting a position of the exhaust gas heat recovery system valve in response to an engine temperature, and where the vehicle operating conditions include an increasing engine temperature.

14. The method of claim 10 , further comprising adjusting a position of the exhaust gas heat recovery system valve in response to a temperature of the heat transfer medium.

15. The method of claim 10 , further comprising routing the heat transfer medium from the engine coolant heat exchanger to a heater core in a vehicle cabin.

16. The engine system of claim 1 , further comprising instructions to adjust the position of the exhaust gas heat recovery system valve to supply working fluid from the evaporator to the engine coolant heat exchanger to transfer heat from the working fluid to coolant in response to a third condition comprising the state of battery charge being greater than the threshold charge and the engine coolant temperature being less than the first threshold temperature.

17. The engine system of claim 16 , wherein, in the third condition, working fluid is supplied from the evaporator solely to the engine coolant heat exchanger responsive to the engine coolant temperature being less than a second threshold temperature, the seco

Assignees

• Ford Global Tech Llc

Inventors

• Hussain Quazi Ehtesham
• Brigham David Richens
• Jennings Mark John

Classifications

• Y10S903/905

  Combustion engine · CPC title

• F02G5/04

  in combination with other waste heat from combustion engines · CPC title

• F01N5/02 Primary

  the devices using heat · CPC title

• Y02T10/166

  Cross-Sectional Technologies · mapped topic

• Y02T10/16

  Cross-Sectional Technologies · mapped topic