Viscous fluid coupling device

Claim 1

A viscous fluid coupling device, comprising: an input member driven by a vehicle engine and having a rotor thereon, an output member rotatably supported on said input member, a partition plate member dividing the interior of said device into an operating chamber for accommodating said rotor and a reservoir chamber for the viscous fluid, labyrinth means between said input member and said output member, aperture means in said rotor radially inwardly of said labyrinth means to provide fluid communication between opposite sides of said rotor, first passage means for sending the viscous fluid from said operating chamber to said reservoir chamber, second and third passage means formed on said partition plate member for communicating said viscous fluid from said reservoir chamber to said operating chamber, a partition wall integrally formed with said partition plate member at the radially inner end of said labyrinth means for directing the flow of fluid passing through said first and second passage means to said labyrinth means, and thermal responsive means for opening and closing said second and third passage means responsive to the change of temperature.