Patent ID: 7435002

Claim:
A bearing unit comprising: a cylindrical oil-impregnated bearing, in which a bearing bore to support a turning shaft is formed so as to enable the turning shaft to turn; a bearing holder, in which the oil-impregnated bearing is fixed by an inner bore; a first groove being formed in an axial direction on an inner circumferential surface of the oil-impregnated bearing; a second groove being formed in an axial direction on at least one of an outer circumferential surface of the oil-impregnated bearing and an inner circumferential surface of the bearing holder; said second groove being formed so as to have a greater depth than that of the first groove; and said second groove being formed so as to have a larger cross section than that of the first groove; wherein the first groove and the second groove are each formed in plural numbers; wherein a total cross section of the second grooves is greater than a total cross section of the first grooves; and wherein a part of the plurality of second grooves is formed so as to be shallower in the depth direction than the other second grooves.