Patent ID: 7775336

Claim:
A friction engagement device comprising: a rotatable, annular first member formed with a concavo-convex spline on an outer periphery thereof, into which a plurality of lubricating oil supply holes are drilled radially; a second member disposed on an outer peripheral side of, and coaxially with, the first member and formed with a concavo-convex spline on an inner periphery thereof; a plurality of first annular plates having friction materials adhered to front and rear surfaces thereof and a plurality of lubricating oil grooves provided therein on the front and rear surfaces so as to penetrate radially, the first annular plates being fitted to the first member by a concavo-convex spline formed on an inner periphery thereof; and a plurality of second annular plates disposed alternately with the first annular plates and fitted to the second member by a concavo-convex spline formed on an outer periphery thereof, the second annular plates being capable of coming into contact with and separating from the friction materials, wherein: the lubricating oil supply holes are drilled into the spline of the first member, and for each spline to which each of the lubricating oil supply holes corresponds, the lubricating oil grooves provided in the plurality of first annular plates do not overlap the splines on at least one of the front and rear surfaces of each of the first annular plates, and the lubricating oil supply holes are provided in the first member alternately by varying the phase thereof in a circumferential direction such that the lubricating oil supply holes formed in one phase are drilled from an axial central part of the first member toward one end, and the lubricating oil supply holes formed in another phase are drilled from the axial central part of the first member toward another end.