Shaft seal device

A shaft seal device for a bearing unit having a bearing fitted on a rotary shaft, and a housing accommodating the rotary shaft extending therethrough, the housing having opposite ends, comprising:

• an annular sealing channel formed in at least one of the opposite ends of the housing, the annular sealing channel having inner end surfaces;
• an annular covering member formed of an elastic material and having an inner peripheral channel formed therein, the annular covering member being fitted in the annular sealing channel in an elastically compressed fashion;
• and
• an annular lubricant-bearing polymer member accommodated in the inner peripheral channel of the annular covering member and fitted on the rotary shaft, the lubricant-bearing polymer member having opposite end surfaces, and an outer peripheral portion,
• wherein the lubricant-bearing polymer member has an inside diameter substantially equal to an outer diameter of the rotary shaft at an initial stage of rotation of the rotary shaft;
• and
• wherein at least part of the opposite end surfaces or the outer peripheral portion of the lubricant-bearing polymer member is disposed substantially in contact with the inner end surfaces of the inner peripheral channel.