Viscous coupling apparatus

Claim 1

In a viscous coupling apparatus for power drive systems comprising: a first rotary member; a second rotary member coaxially disposed relative to said first rotary member such that said first and second rotary members are rotatable with respect to each other; a hermetically sealed fluid chamber disposed between said first and second rotary members defined by an outer drum assembly fixably secured to one of said first and second rotary members and an inner drum housing fixably secured to the other of said first and second rotary members, said outer drum assembly including an outer drum housing and front and rear annular end cover plates fixably secured thereto; a set of first viscous clutch plates disposed within said fluid chamber and coupled to said outer drum housing for rotation with said first rotary member; a set of second viscous clutch plates disposed in said fluid chamber and coupled to said inner drum housing for rotation with said second rotary member, said sets of first and second viscous clutch plates being alternately interleaved such that outermost plates of said first clutch plates are adjacent each of said end plate covers; viscous fluid disposed within said fluid chamber, said first and second viscous clutch plates being operative to transmit torque between said first and second rotary members in response to the viscous resistance of said viscous fluid between said interleaved clutch plates within said fluid chamber; and a plurality of annular spacer rings each of which is interposed between adjacent second clutch plates for longitudinally positioning said second clutch plates so as to define a predetermined spacing therebetween, the improvement comprising: an axially extending stop projection means formed on each of said front and rear end cover plates of said outer drum assembly and which extend longitudinally into said fluid chamber, said stop projection means being located radially inwardly of an inner peripheral edge surface of said outermost plates of said first clutch plates to permit axial sliding movement thereof with respect to said stop projection means said stop projection means for inhibiting excessive axial sliding movement of said second clutch plates located adjacent to said stop projection means for cooperating with said annular spacer rings to maintain said predetermined spacing of said second clutch plates within said fluid chamber.