Clutch assembly

Abstract

A viscous fluid clutch for use as a clutch for a cooling fan for a vehicle, the clutch includes an input shaft, a rotor assembly, a first housing portion, a second housing portion, a coil assembly, and a brush box. The rotor assembly is coupled to the input shaft. The first housing portion is coupled to the second housing portion and the second housing portion is rotatably disposed on the input shaft. The first and second housing portions define a fluid reservoir for receiving the rotor assembly and a viscous fluid, preferably of the magnetorheological type. The coil assembly is coupled to the first housing portion. The brush box is operably coupled to the coil assembly. When the coil assembly is energized by the brush box, a magnetic field is created that acts upon the magnetorheological fluid to vary the torque transfer of the input shaft to the housing and the fan connected thereto.

What is claimed is: 
     
         1 . A viscous fluid clutch comprising:
 an input shaft;   a rotor assembly coupled to the input shaft;   an annular housing insert;   a housing including a first housing portion cast around the housing insert and a second housing portion connected for rotation with the first housing portion and rotatably disposed on the input shaft; and   a coil assembly including a coil body and a coil cover;   wherein the coil body is disposed between the housing insert and the coil cover; and   wherein the coil cover is coupled to the housing insert.   
     
     
         2 . The viscous fluid clutch of  claim 1 , wherein the coil cover is laser welded to the housing insert. 
     
     
         3 . The viscous fluid clutch of  claim 1 , further comprising at least one fastener coupling the coil cover to the housing insert. 
     
     
         4 . The viscous fluid clutch of  claim 3 , wherein the fastener is a screw. 
     
     
         5 . The viscous fluid clutch of  claim 1 , wherein the volume of space between the housing insert, the coil body, and the coil cover is minimized.