Patent ID: 6121526
Filing Date: 2000-09-19
Classification: F16F

Abstract:
A rotary damper comprising:a tubular casing having a chamber defined therein;a viscous fluid filled in said chamber;a shaft having a portion accommodated in said chamber and having a support shaft portion connectable to an external member, said shaft being rotatable with respect to said tubular casing;a first ridge extending axially along and projecting radially outwardly from an outer circumferential surface of said portion of the shaft which is accommodated in said chamber, said first ridge having a radially outer end face disposed for sliding contact with an inner circumferential surface of said tubular casing;a second ridge extending axially along and projecting radially inwardly from said inner circumferential surface of said tubular casing, said second ridge having a radially inner end face held in sliding contact with said radially outer circumferential surface of said portion of the shaft which is accommodated in said chamber;said first ridge and said second ridge cooperating with each other in limiting said shaft and said tubular casing to relative rotation within a predetermined range, and dividing an interior of said chamber into a first compartment and a second compartment, the volume of said first and second compartments being variable complementarily to each other in response to said relative rotation of said shaft and said casing; andtorque control means for generating a higher torque or a lower torque depending on the direction in which said shaft rotates with respect to said tubular casing, by controlling a flow of said viscous fluid between said first compartment and said second compartment when shaft rotates with respect to said tubular casing;said torque control means comprising an auxiliary chamber defined in said tubular casing by a partition wall adjacent to said chamber in communication with said chamber, first and second communication holes defined in said partition wall and providing fluid communication between said first and second compartments and said auxiliary chamber, and a check valve for preventing said viscous fluid from flowing in said first communication hole from said auxiliary chamber toward said first compartment.