Half-engage clutch point learning device for wet multiple disk clutch

Abstract

A power transmission device for a vehicle equipped with a wet multiple disk clutch for disconnecting the power at the time of gearshift by using a clutch controller, wherein the amount of engagement where the clutch is half-engaged is learned maintaining precision. In the present invention, the clutch controller of the wet multiple disk clutch moves a clutch piston over the whole stroke thereof by using the working fluid for varying the amount of engagement at the start of learning the amount of engagement at a point where the clutch starts half-engaging and, immediately thereafter, the amount the clutch is half-engaged is detected. Upon moving the clutch piston, the working fluid present among the friction disks of the wet multiple disk clutch is drained and is replaced by the new working fluid avoiding detection error caused by the fluctuation in the temperature of the working fluid and eliminating unstable operation of the clutch piston caused by static friction of a large resistance. The amount of engagement at the point where the clutch starts half-engaging is determined by gradually increasing the amount of engagement after the clutch is disengaged and detecting a change in the rotational speed of the clutch input shaft.