Method and means for switching on and off the fan wheel of a regulating fan

Claim 1

In a fan arrangement for cooling an engine, the arrangement including a rotatable fan wheel, a drive member adapted to be rotated by said engine, a clutch operatively interposed between said drive member and said wheel for drivingly connecting said member to said wheel, and temperature responsive clutch-operating means including a movable actuating member, a body of temperature sensitive material in thermal contact with ambient air and connected to said actuating member for moving the same in response to a change in the temperature of said air, and motion-transmitting means connecting said actuating member to said clutch for engaging and disengaging the clutch in response to movement of the actuating member, the motiontransmitting means including two clamping members mounted for relative angular movement about an axis movement, a first one of said clamping members being connected to said actuating member for movement thereby in the direction of said axis, and to said drive member for rotation thereby about said axis, coupling means for connecting the second coupling member to said wheel in response to an axial movement of said second clamping member from a first to a second position and for thereby displacing the two clamping members angularly relative to each other when the rotary speeds of said fan wheel and of said drive member differ from a predetermined relationship, and cam means interposed between said clamping members for further axially moving said second clamping member from said second position toward a third axial position away from said first position, and for thereby engaging said clutch in response to said angular displacing, the improvement which comprises: a. said cam means including a cam member on one of said clamping members having a first face sloping obliquely in a circumferential direction and axially toward the other clamping member and a second cam face offset from said first face in said circumferential direction and leading away from said other clamping member; b. the cam means further including cam follower means on said other clamping member for engagement with said cam member; and c. yieldably resilient means holding said cam follower means in consecutive abutting engagement with said first and second faces during angular movement of said clamping members relative to each other in one direction, whereby said clamping members are moved apart and thereafter moved toward each other during said angular movement in said one direction.