Transmission thermostat device

1. A transmission thermostat device comprising:

a body including first and second input ports and first and second output ports;

a first fluid path extending between the first input port and the first output port;

a second fluid path extending between the second input port and the second output port; at least one bypass port disposed between the first fluid path and the second fluid path;

at least one temperature sensing mechanism disposed within the housing, the at least one temperature sensing mechanism operative in a first mode to dose the at least one bypass port and in a second mode to open the at least one bypass port, the at least one temperature sensing mechanism including a bimetal element responsive to a change in temperature; and

wherein the at least one temperature sensitive mechanism includes first and second bimetal elements, the first and second bimetal elements having distinct opening and closing characteristics that can be combined to tune the behavior of the thermostat device.

2. The transmission thermostat of claim 1 , wherein the bimetal element doses the bypass port at a predetermined temperature.

3. The transmission thermostat device of claim 2 , wherein the valve element is pivotally carried by the bimetal element.

4. The transmission thermostat of dam 1 , wherein the bimetal is U-shaped.

5. The transmission thermostat device of dam 1 , wherein the bimetal is shaped like a straight beam.

6. The transmission thermostat device of dam 1 , wherein the bimetal includes a pair of U-shaped portions.

7. The transmission thermostat device of claim 1 , wherein the at least one temperature sending mechanism includes first and second bimetal elements, the first and second bimetal elements having substantially identical shape, thickness and material.

8. The transmission thermostat device of claim 1 , further comprising an internal pressure relief mechanism disposed in the housing for limiting pressure to a predetermined level.

9. The transmission thermostat of claim 8 , wherein the pressure relief mechanism includes a spring loaded ball for normally closing a bypass port.

10. The transmission thermostat device of claim 1 wherein the bimetal element is coil shaped.

11. The transmission thermostat device of claim 1 , further comprising a valve element carried by the bimetal element for opening and closing the bypass port.

12. A thermostat device for selectively cooling fluid of a vehicle transmission, the thermostat device comprising:

a housing with a first input port to receive fluid from the vehicle transmission, a first output port leading to a fluid cooling device, a second input port for fluid coming back from the fluid cooling device and a second output port leading the fluid back to the transmission; a first fluid path in the housing between the first input port and the first output port;

a second fluid path between the second input port and the second output port;

at least one bypass port extending between the first and second fluid paths;

at least one bimetal element for opening and closing the at least one bypass port; and;

wherein the at least one bypass port includes first and second bypass ports and the thermostat device further includes first and second valves controlled a balanced way such that a fluid pressure opens the first valve while at the same time closes the second valve so as to result in a zero net force situation.

13. A cooling arrangement for selectively and automatically cooling fluid of a vehicle transmission, the cooling arrangement comprising:

a cooling device;

a thermostat device;

a fluid loop for normally routing fluid between the transmission and the cooling device, the fluid loop including first and second portions passing through the thermostat device;

at least one bypass port in the thermostat device, the at least one bypass port extending between the first and second portions of the fluid path;

at least one temperature responsive bypass mechanism in the thermostat device, the at least one temperature responsive bypass element including a bimetal element and operative in a first mode to close the at least one bypass port and in a second mode to open the at least one bypass port; and

a pressure relief mechanism for relieving pressure in the first portion of the fluid loop, the pressure relief mechanism including a pressure sensitive member normally closing a pressure relief port and opening the pressure relief port upon a predetermined pressure in the first portion of the fluid path.

14. The cooling arrangement for selectively and automatically cooling fluid of a vehicle transmission of claim 13 , wherein a fluid resistance of the at least one bypass port is lower than a fluid resistance of the cooling device.

15. The cooling arrangement for selectively and automatically cooling fluid of a vehicle transmission of claim 13 , wherein the bimetal element automatically changes from the first mode to the second mode at a predetermined temperature.

16. The cooling arrangement for selectively and automatically cooling fluid of a vehicle transmission of claim 13 , wherein the pressure relief mechanism includes a ball normally biased into seating engagement with a pressure relief port.