Patent ID: 9291211
Filing Date: 2016-03-22
CPC Classification: F16D

Claim Text:
1. A wet friction material comprising: an annular core plate, a plurality of segment pieces bonded in an annular arrangement on a specific one surface or on both surfaces of the core plate, and inter-segment grooves formed between adjacent ones of the segment pieces, wherein each of the segment pieces has at least two inner peripheral recesses formed on an inner periphery thereof, wherein the segment pieces include width-decreasing segment pieces each of which has a circumferential width gradually decreasing from an inner peripheral side to an outer peripheral side thereof with increasing radius so that the inter-segment groove formed between adjacent ones of the width-decreasing segment pieces has a circumferential width gradually increasing from the inner peripheral side to the outer peripheral side, wherein the inner peripheral recess has a recessed amount within a range of 1/10 to ⅓ of a radial width of the segment piece, and wherein the segment pieces include width-increasing segment pieces each of which has a circumferential width gradually increasing from an inner peripheral side to an outer peripheral side thereof with increasing radius.