Abstract: Provided is a wet friction plate which can realize a further reduction of drag torque while suppressing a decrease in the total area of frictional sheets. A clutch friction plate 200 is formed by providing frictional sheets 210 and oil grooves 220 on a flat annular metal core 201. On a side surface of the metal core 201 facing a clutch plate 103, a plurality of small frictional sheets 210 and oil grooves 220 are alternatingly arranged along the circumferential direction of the metal core 201. The frictional sheets 210 are disposed to form frictional-sheet groups 211 each including five frictional sheets 210 disposed successively. Outer and inner peripheral edges 213 and 214 of the frictional sheets 210 of each frictional-sheet group 211 form continuously changing arcuate contours 213a and 214a such that the distances L213 and L214 between the outer and inner peripheral edges 213 and 214 and the center of rotation O of the metal core 201 continuously change.

Abstract: Provided is a wet friction plate which can realize a further reduction of drag torque while suppressing a decrease in the total area of frictional sheets. A clutch friction plate 200 is formed by providing frictional sheets 210 and oil grooves 220 on a flat annular metal core 201. On a side surface of the metal core 201 facing a clutch plate 103, a plurality of small frictional sheets 210 and oil grooves 220 are alternatingly arranged along the circumferential direction of the metal core 201. The frictional sheets 210 are disposed to form frictional-sheet groups 211 each including five frictional sheets 210 disposed successively. Outer and inner peripheral edges 213 and 214 of the frictional sheets 210 of each frictional-sheet group 211 form continuously changing arcuate contours 213a and 214a such that the distances L213 and L214 between the outer and inner peripheral edges 213 and 214 and the center of rotation O of the metal core 201 continuously change.

Abstract: A clutch which can realize further reduction of drag torque, a method for reducing the drag torque of the clutch, and a clutch friction plate used in the clutch are provided. In a clutch 100, clutch plates 103 and clutch friction plates 110, both of which are flat and annular, are alternatingly arranged, and clutch oil is supplied to spaces between the clutch plates 103 and the clutch friction plate 110. Each clutch friction plate 100 has small-groove groups 113 and fan-shaped grooves 114 formed on a surface of a metal core 111, which is flat and annular. Each small-groove group 113 includes a plurality of small grooves 113a which are parallel to one another and extend from the inner peripheral side to the outer peripheral side of the metal core 111. Each fan-shaped groove 114 is formed adjacent to the corresponding small-groove group 113 such that its width increases from the inner peripheral side toward the outer peripheral side of the metal core 111.