Fluid coupling device and bimetal coil for use therein

A fluid coupling device comprising:

• a. a first rotatable member defining an axis of rotation and a fluid chamber;
• b. a second rotatable member disposed in said fluid chamber and being rotatable relative to said first member;
• c. cover means associated with said first member for rotation therewith;
• d. means separating said fluid chamber into a fluid operating chamber and a fluid reservoir chamber;
• e. valve means including a movable valve member operable to control the flow of fluid between said operating chamber and said reservoir chamber, and further including a valve shaft having an inner end disposed within said fluid chamber and an outer end extending outwardly from said cover means, said movable valve member being operatively associated with said inner end of said valve shaft;
• f. said cover means including a cover member and a generally cylindrical support insert having its axis coincident with said axis of rotation, said support insert having said valve shaft rotatably disposed therein, said support insert projecting outwardly beyond said cover member and having a radius R;
• g. a bimetal coil operable to control the rotational position of said valve shaft, said bimetal coil having a first end portion connected to said outer end of said valve shaft, and a second end portion mounted relative to said cover means;
• and
• h. said bimetal coil defining a nominal width over a major portion of its length and including an initial portion, adjacent said first end portion, having a width substantially less than said nominal width, said bimetal coil defining a progressively increasing radius about said axis of rotation, and said initial portion of said coil extending along said coil to a point at which said coil defines a radius RC, said radius RC being slightly greater than the radius R of said support insert, to permit said major portion of said coil to be disposed closely spaced from said cover member.