To reduce torque changing speed in changing over a torque characteristic by forming the receiving hole a check ball opening a relief hole to relief oil pressure of the high pressure chamber of a valve by oscillation of a weight into a valve, and making the contact face of the check ball receiving hole into a plurality of step tapers.
The contact face of a receiving hole 74 is formed with a first step taper part 75 continued to a relief hole 72, and a second step taper part 76 continued to the taper part 75. When vehicle speed becomes over fixed speed, to be ΔP.e + centrifugal force > F(ΔP is oil pressure, (e)is contact area acting on a check ball 73, F is pressing force to the check ball 73), the check ball 73 opens the relief hole 72. When the check ball 73 opens the relief hole 72, change of a flow passage capacity against the moving quantity of the check ball 73 becomes moderate, and change of torque characteristic to change of flow variation becomes moderate. Hereby, torque change speed becomes moderate, an inifluence on the vehicle behavior can be reduced.
KATO TADAHIKO
TAJIMA YOSHIAKI
TAKASAKI TOSHIHARU
KUSUKAWA HIROTAKA
MURATA SHIGEO
NISSAN MOTOR