EXHAUST THROTTLING FOR CABIN HEATING

• US 20150121848A1
• Filed: 11/05/2013
• Published: 05/07/2015
• Est. Priority Date: 11/05/2013
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Pursifull, Ross Dykstra
• Granted Patent: US 9,334,783 B2
• Time in Patent Office: Days
• US Class Current: 60/274
• CPC Class Codes: F01N 5/02 the devices using heat
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

Embodiments for heating a vehicle cabin are disclosed. In one example, a method for an engine comprises pumping coolant from a coolant reservoir to an exhaust component and then to a heater core, the coolant heated by the exhaust component, and during engine warm-up conditions, adjusting a flow rate of coolant into a heater core to maximize heat transfer to a vehicle cabin.

Claims

1. A method for an engine, comprising:

pumping coolant from a coolant reservoir to an exhaust component and then to a heater core, the coolant heated by the exhaust component; and

during engine warm-up conditions, adjusting a flow rate of coolant into the heater core based on a temperature drop across the heater core and a commanded flow rate of coolant into the heater core to maximize heat transfer to a vehicle cabin.

2. The method of claim 1, wherein adjusting the flow rate of coolant into the heater core to maximize heat transfer to the vehicle cabin comprises flowing the coolant at less-than-maximum flow rate even if a heat demand of the vehicle cabin is at a maximum heat demand.

3. The method of claim 1, wherein adjusting the flow rate of coolant into the heater core comprises adjusting the flow rate to a desired flow rate of coolant associated with a given operating condition determined based on a relationship between the temperature drop across the heater core and the commanded flow rate of coolant into the heater core.

5. The method of claim 3, wherein the desired flow rate provides maximum heat transfer to the vehicle cabin for the given operating condition.

6. The method of claim 1, wherein the exhaust component is an exhaust gas recirculation (EGR) cooler, wherein the reservoir is the engine, and further comprising routing the coolant into the heater core from the EGR cooler via a circulation pump, the coolant from the heater core routed through the engine before returning to the EGR cooler.

7. The method of claim 6, wherein adjusting the flow rate comprises adjusting a flow rate of the circulation pump.

8. The method of claim 6, further comprising closing an exhaust throttle while diverting at least a portion of throttled exhaust gas through the EGR cooler coupled upstream of the throttle to heat the EGR cooler, heat from the EGR cooler transferred to the coolant.

9. The method of claim 8, wherein diverting the portion of the throttled exhaust gas through the EGR cooler includes diverting a portion of the throttled exhaust gas through the EGR cooler located inside an EGR passage while maintaining an EGR valve in the EGR passage at a more closed position, the EGR passage fluidly coupling an engine exhaust from upstream of the exhaust throttle to an engine intake, upstream of an intake compressor.

10. The method of claim 1, wherein the engine warm-up conditions comprise a temperature of the engine being below a threshold temperature, and further comprising, when the temperature of the engine is above the threshold temperature, maintaining a constant flow rate of coolant into the heater core.

4. (canceled)

11. A vehicle system, comprising:

an engine including an intake and an exhaust;

an exhaust gas recirculation (EGR) passage coupling the exhaust to the intake, the EGR passage including an EGR cooler and an EGR valve;

a cabin heating system including a heater core and a circulation pump configured to pump coolant from the EGR cooler to the heater core; and

a controller including instructions to, during a cabin heating mode, adjust a flow rate of coolant into a heater core based on a determined relationship between a temperature drop across the heater core and the flow rate of coolant into the heater core.

12. The vehicle system of claim 11, wherein the controller further includes instructions to adjust the flow rate of coolant to a desired flow rate that provides a maximum cabin power, the maximum cabin power a function of the temperature drop across the heater core and the desired flow rate.

13. The vehicle system of claim 11, wherein the flow rate is determined by the controller based on a power of the circulation pump.

14. The vehicle system of claim 11, further comprising:

an EGR bypass coupled across the EGR cooler; and

an exhaust throttle positioned in the exhaust downstream of an inlet of the EGR passage and upstream of an outlet of the EGR bypass.

15. The vehicle system of claim 14, wherein the controller further includes instructions to, during the cabin heating mode, close the exhaust throttle and the EGR valve to push throttled exhaust through the EGR cooler and back to the exhaust via the EGR bypass to heat the EGR cooler.

16. A method, comprising:

pumping coolant with a circulation pump through a cabin heating circuit comprising an EGR cooler, a cabin heater core, and an engine;

during steady state conditions where a temperature of the coolant into the heater core is above a threshold temperature, operating the circulation pump at maximum power to flow coolant into the heater core at a maximum flow rate; and

during non-steady state conditions where the temperature of the coolant into the heater core is below the threshold temperature, adjusting the circulation pump to flow coolant into the heater core at a less-than-maximum flow rate, the less-than-maximum flow rate selected to provide maximum cabin heat.

17. The method of claim 16, wherein adjusting the power of the circulation pump comprises adjusting the power of the circulation pump based on a temperature drop across the heater core and a flow rate of the coolant into the heater core.

18. The method of claim 17, further comprising, as the temperature drop increases, adjusting the circulation pump to increase the flow rate and as the temperature drop decreases, adjusting the circulation pump to decrease the flow rate.

19. The method of claim 16, further comprising during the non-steady state conditions, throttling exhaust gas to increase exhaust pressure and to route exhaust gas through the EGR cooler to heat the EGR cooler, the throttling of the exhaust gas comprising closing an exhaust throttle positioned in the engine exhaust.

20. The method of claim 19, further comprising, responsive to an EGR valve downstream of the EGR cooler being closed, routing the throttled exhaust from the EGR cooler back to the engine exhaust, downstream of the exhaust throttle, via an EGR bypass, and responsive to the EGR valve being at least partially open, routing exhaust from the EGR cooler to an engine intake.