Vehicle exhaust and air-circulation system for cold start

1. A vehicle comprising:

an engine including an intake manifold and an exhaust manifold;

an exhaust system connected to the exhaust manifold and including an aftertreatment device, the aftertreatment device having a body defining inlet and outlet cones, a heating element, and a catalyst disposed in the body between the cones; and

an air-circulation system including conduit extending from downstream of the catalyst to the intake manifold and an air-circulation device configured to circulate air from the outlet cone, through the conduit, wherein the air-circulation system further includes a bypass conduit connected between the conduit and the inlet cone.

2. The vehicle of claim 1 , wherein the conduit is in fluid communication with the outlet cone.

3. The vehicle of claim 1 further comprising an electric machine operably coupled to the engine.

4. The vehicle of claim 1 , wherein the air-circulation device includes an electric fan.

5. The vehicle of claim 1 further comprising a controller programmed to:

in response to a request to start the engine and a temperature of the catalyst being below a threshold, open all intake and exhaust valves of the engine, energize the heating element, energize the air-circulation device, and inhibit starting of the engine, and

in response to the request to start the engine and the temperature of the catalyst exceeding the threshold, de-energize the heating element and the air-circulation device, and command starting of the engine.

6. The vehicle of claim 1 , wherein the engine further includes intake and exhaust valves, and further comprising:

a temperature sensor disposed in the body downstream of the heating element and configured to output temperature data indicative of a measured temperature; and

a controller programmed to:

in response to a request to start the engine and the measured temperature being below a threshold, energize the heating element, energize the air-circulation device, open all of the intake and exhaust valves so that the air-circulation system circulates the air through the engine, and inhibit starting of the engine, and

in response to the measured temperature exceeding the threshold and the request to start the engine, de-energize the heating element and the air-circulation device, and command starting of the engine.

7. The vehicle of claim 1 , wherein the air-circulation system further includes a valve configured to circulate the air to the engine when in a first position and to the bypass conduit when in a second position.

8. The vehicle of claim 7 further comprising a controller programmed to:

in response to a request to start the engine and a temperature of the catalyst being below a first threshold, energize the heating element, energize the air-circulation device, actuate the valve to the second position, and inhibit starting of the engine,

in response to the temperature of the catalyst exceeding the first threshold and being less than a second threshold, open all intake and exhaust valves of the engine, actuate the valve to the first position, and inhibit starting of the engine, and

in response to the temperature of the catalyst exceeding the first and second thresholds and the request to start the engine, de-energize the heating element and the air-circulation device and command starting of the engine.

9. The vehicle of claim 7 further comprising a controller programmed to:

in response to a request to start the engine and a temperature of the catalyst being below a first threshold, energize the heating element, energize the air-circulation device, actuate the valve to the second position, and inhibit starting of the engine,

in response to the temperature of the catalyst exceeding the first threshold and being less than a second threshold, open all intake and exhaust valves of the engine, actuate the valve to the first position, and inhibit starting of the engine, and

in response to the temperature of the catalyst exceeding the first and second thresholds and a temperature of the engine exceeding a third threshold, de-energize the heating element and the air-circulation device and command starting of the engine.

10. The vehicle of claim 7 further comprising a controller programmed to:

in response to a request to start the engine and a temperature of the catalyst being below a first threshold, energize the heating element, energize the air-circulation device, actuate the valve to the second position, and inhibit starting of the engine,

in response to the temperature of the catalyst exceeding the first threshold and a temperature of the engine being less than a second threshold, open all intake and exhaust valves of the engine, actuate the valve to the first position, and inhibit starting of the engine, and

in response to the temperature of the catalyst exceeding a third threshold, the temperature of the engine exceeding the second threshold, and the request to start the engine, de-energize the heating element and the air-circulation device and command starting of the engine.

11. The vehicle of claim 10 further comprising an electric machine, wherein the controller is further programmed to, in response to the engine being inhibited from starting and a driver-demanded torque being received, command the driver-demanded torque to the electric machine.

12. A vehicle comprising:

an engine including an intake manifold;

an exhaust aftertreatment device having an inlet cone, an outlet cone, and a heating element;

an air-circulation system including an air-circulation device configured to circulate air from the outlet cone to the intake manifold, wherein the air-circulation system further includes a bypass conduit connected between the conduit and the inlet cone; and

a controller programmed to:

in response to a request to start the engine and a temperature of the aftertreatment device being below a threshold, energize the heating element, energize the air-circulation device, and inhibit starting of the engine, and

in response to the temperature of the aftertreatment device exceeding the threshold and the request to start the engine, de-energize the heating element and the air-circulation device, and command starting of the engine.

13. The vehicle of claim 12 , wherein the air-circulation device is a fan.

14. A vehicle comprising:

an engine including an intake manifold;

an exhaust aftertreatment device having an inlet cone, an outlet cone, and a heating element;

an air-circulation system including an air-circulation device configured to circulate air from the outlet cone to the intake manifold, wherein the air-circulation system further includes a valve having a first inlet in fluid communication with the air-circulation device, a first outlet in fluid communication with the intake manifold, and a second outlet in fluid communication with the inlet cone, and wherein the valve is configured to connect the outlet cone and the intake manifold in fluid communication when in a first position and to connect the outlet cone and the inlet cone in fluid communication when in a second position; and

a controller programmed to, in response to a request to start the engine and a temperature of the aftertreatment device being below a threshold, energize the heating element, energize the air-circulation device, and inhibit starting of the engine.

15. The vehicle of claim 14 , wherein the controller is further programmed to, in response to the request to start the engine and the temperature of the aftertreatment device being below the threshold, open all intake and exhaust valves of the engine.

16. The vehicle of claim 14 , wherein the air-circulation device is a fan.

17. The vehicle of claim 14 , wherein the controller is further programmed to, in response to the temperature of the aftertreatment device exceeding the threshold and the request to start the engine, de-energize the heating element and the air-circulation device, and command starting of the engine.

18. The vehicle of claim 14 , wherein the controller is further programmed to, in response to the temperature of the aftertreatment device being less the threshold, actuate the valve to the second position.

19. The vehicle of claim 18 , wherein the controller is further programmed to, in response to the temperature of the aftertreatment device exceeding the threshold and being less than a second threshold, actuate the valve to the first position.