An oil cooler for a motor vehicle includes a fluid inlet tank and a fluid outlet tank. A plurality of heat transfer tubes provides constant fluid communication between the inlet tank and the outlet tank. A bypass arrangement provides additional fluid communication between the fluid inlet tank and the fluid outlet tank under a first operating condition and the bypass arrangement precludes additional fluid communication between the inlet tank and the outlet tank under a second operating condition. The bypass arrangement may include a bypass tube and an element for selectively blocking the bypass tube. The element for selectively blocking the bypass tube may be automatically response to a change in oil temperature or a change in oil pressure.
1. An oil cooler for cooling oil of a motor vehicle, the oil cooler comprising:
a fluid inlet tank;
a fluid outlet tank;
a plurality of heat transfer tubes providing constant fluid communication between the inlet tank and the outlet tank; and
at least one bypass tube for selectively providing additional fluid communication between the fluid inlet tank and the fluid outlet tank; and
a bi-metallic valve moveable from a first position to a second position in response to an increase in temperature of the oil such that the valve member closes the at least one bypass tube to preclude additional fluid communication between the fluid inlet tank and the fluid outlet tank when the valve member is in the second position and the valve member opens the bypass tube to provide additional fluid communication between the inlet tank and the outlet tank in the first position.
2. The oil cooler of claim 1 , wherein the valve member is a temperature responsive valve.
3. The oil cooler of claim 2 , where the temperature responsive valve includes a bi-metal element movable from the first position to the second position in response to a change in temperature.
4. The oil cooler of claim 3 , wherein the bi-metal element is a strip that is generally U-shaped.
5. The heat exchanger of claim 3 , wherein the bi-metal element is a strip shaped in the form of a curved or a convoluted beam.
6. The oil cooler of claim 1 , wherein the oil cooler is a transmission oil cooler.
7. The oil cooler of claim 1 , wherein the oil cooler is an engine oil cooler.
8. A method of cooling oil of a cooler for a motor vehicle, the oil cooler including a fluid inlet tank, a fluid outlet tank, and a plurality of heat transfer tubes providing constant fluid communication between the inlet tank and the outlet tank, the method including:
providing a bypass arrangement for selectively providing additional fluid communication between the fluid inlet tank and the fluid outlet tank;
operating the cooler under a first operating condition wherein the temperature of the oil is below a predetermined temperature and the bypass arrangement provides additional fluid communication between the fluid inlet tank and the fluid outlet tank; and
operating the cooler under a second operating condition wherein the temperature of the oil is above the predetermined temperature and the bypass arrangement precludes additional fluid communication between the inlet tank and the outlet tank under a second operating condition.