VISCOUS COUPLING

PURPOSE:To aim at stabilization in a torque characteristic, by installing an expansion chamber filled with gas, and also installing a free piston, separating the gas from viscous liquid and being shiftable to either side, between the expansion chamber and a liquid chamber. CONSTITUTION:A lot of clutch plates 15 at the output shaft side are installed inside the casing 10 tightly attached to an output shaft 11, and an input shaft 13 installing clutch plates 16 at the input shaft side corresponding to these plates 15 in the circumference are installed inside the casing 10 free of relative rotation. On the other hand, a cavity part 13b is formed inside the input shaft 13, while a free piston 17 and an oil seal 18 are set up in this cavity part free of slide motion, installing a liquid passage 13c and a gas seal port 13d there, and viscous liquid such as silicone oil or the like is filled in a liquid chamber A while gas such as nitrogen or the like is filled in an expansion chamber B. Therefore, such a coupling torque characteristic as being stable against an extensive temperature change in the viscous liquid is secured and, what is more, durability and reliability are improvable.