Thermoelectric generator cooling system and method of control

1. An apparatus comprising:

an engine;

a thermoelectric generator having an exhaust gas inlet and an exhaust gas outlet;

an exhaust gas passage operatively connecting the engine and the exhaust gas inlet of the thermoelectric generator to permit exhaust gas flow through the thermoelectric generator from the exhaust gas inlet to the exhaust gas outlet;

a plurality of coolant flow passages defining a coolant circuit operatively connecting the engine and the thermoelectric generator; wherein the thermoelectric generator has a first coolant port and a second coolant port; wherein the first coolant port is nearer to the exhaust gas outlet than to the exhaust gas inlet; wherein the second coolant port is nearer to the exhaust gas inlet than to the exhaust gas outlet;

at least one valve positioned in the coolant circuit and movable between a first position and a second position; wherein the at least one valve is in the first position under a first set of operating conditions and is in the second position under a second set of operating conditions; wherein the at least one valve directs coolant flow through the thermoelectric generator from the first coolant port to the second coolant port when in the first position and directs coolant flow through the thermoelectric generator from the second coolant port to the first coolant port when in the second position.

2. The apparatus of claim 1 , wherein the first set of operating conditions includes at least one of temperature of the thermoelectric generator less than a predetermined temperature, and exhaust gas temperature upstream of the exhaust gas inlet below another predetermined temperature; and wherein the second set of operating conditions includes at least one of temperature of the thermoelectric generator greater than the predetermined temperature and less than a preselected temperature, and exhaust gas temperature upstream of the exhaust gas inlet above the predetermined temperature and less than the another predetermined temperature.

3. The apparatus of claim 1 , wherein the first set of operating conditions includes engine loading below a predetermined load; and wherein the second set of operating conditions includes engine loading above the predetermined load.

4. The apparatus of claim 1 , further comprising:

a bypass valve movable to direct at least a portion of the exhaust gas flow away from the thermoelectric generator under a third set of operating conditions.

5. The apparatus of claim 1 , wherein the at least one valve includes a first valve and a second valve; wherein the first valve is configured to direct coolant flow from the engine to the first coolant port and the second valve is configured to direct coolant flow from the second coolant port to the engine when each is in the respective first position; and wherein the first valve is configured to direct coolant flow from the engine to the second coolant port and the second valve is configured to direct coolant flow from the first coolant port to the engine when each is in the respective second position.

6. The apparatus of claim 1 , wherein the at least one valve is an H valve configured to direct coolant flow from the engine to the first coolant port and from the second coolant port to the engine when in the first position, and to direct coolant flow from the first coolant port to the engine and from the engine to the second coolant port when in the second position.

7. An apparatus comprising:

a thermoelectric generator;

an exhaust gas system operatively connected to the thermoelectric generator to heat a portion of the thermoelectric generator with exhaust gas flow through the thermoelectric generator;

a coolant system operatively connected to the thermoelectric generator to cool another portion of the thermoelectric generator with coolant flow through the thermoelectric generator;

at least one valve controllable to cause the coolant to flow through the thermoelectric generator in a direction that opposes a direction of the exhaust gas flow under a first set of operating conditions and to cause the coolant to flow through the thermoelectric generator in the direction of exhaust gas flow under a second set of operating conditions.

8. The apparatus of claim 7 , further comprising:

a bypass valve movable to direct at least a portion of the exhaust gas flow away from the thermoelectric generator under a third set of operating conditions.

9. The apparatus of claim 7 , wherein the at least one valve includes a first valve and a second valve; wherein the first valve is configured to direct coolant flow from the engine to a first coolant port of the thermoelectric generator and the second valve is configured to direct coolant flow from a second coolant port of the thermoelectric generator to the engine when each is controlled to be in a respective first position; wherein the first valve is configured to direct coolant flow from the engine to the second coolant port and the second valve is configured to direct coolant flow from the first coolant port to the engine when each is controlled to be in a respective second position; and wherein the second coolant port is nearer the exhaust gas inlet than the first coolant port.

10. The apparatus of claim 7 , wherein the at least one valve is an H valve configured to direct coolant flow from the engine to a first coolant port of the thermoelectric generator and from a second coolant port of the thermoelectric generator to the engine when the at least one valve is controlled to be in a first position, and to direct coolant flow from the first coolant port to the engine and from the engine to the second coolant port when the at least one valve is controlled to be in a second position; and wherein the second coolant port is nearer the exhaust gas inlet than the first coolant port.

11. A method for controlling temperature of a thermoelectric generator in an automotive exhaust gas system comprising:

directing coolant in a first direction through the thermoelectric generator under a first set of operating conditions; and

directing coolant in a second direction opposing the first direction through the thermoelectric generator under a second set of operating conditions; wherein exhaust gas flows through the thermoelectric generator in the second direction under both the first and the second sets of operating conditions.

12. The method of claim 11 , further comprising:

sensing the operating conditions; and

wherein the directing coolant in the first and the second directions includes actuating a valve in response to the sensed operating conditions.

13. The method of claim 11 , further comprising:

moving a bypass valve to direct at least a portion of the exhaust gas flow away from the thermoelectric generator under a third set of operating conditions.