POWER TRANSMISSION DEVICE

摘要

PROBLEM TO BE SOLVED: To securely regulate an upper limit of transmission torque when an excessive difference in relative rotation between an inner rotary body and an outer rotary body occurs with required characteristics. SOLUTION: A pressure and centrifugal force sensitive valve 80 displaces a valve element 81 on an outer side in the radial direction against energizing force of a spring member 82 and opens a first release flow passage 32 due to relative rotation of a hub 11 and a housing 12 when at least either of the conditions that a pressure in a pressure chamber 31 exceeds the predetermined pressure and the pressure exceeding the predetermined pressure acts on the valve element 81 or the housing 12 rotates at a speed exceeding the predetermined speed and a centrifugal force exceeding the predetermined force acts on the valve element 81 is satisfied. Moreover, a temperature sensitive valve displaces the valve element against energizing force of the spring member through a piston pin in accordance with thermal inflation of wax and opens a second release flow passage when the wax of a wax element reaches a temperature exceeding the predetermined temperature.