Patent ID: 8690435

Claim:
A dynamic pressure bearing comprising: a shaft arranged along a central axis extending in a vertical direction; and a sleeve portion arranged to support a circumference of the shaft; wherein the shaft and the sleeve portion are arranged to define a gap therebetween; at least one of an outer circumferential surface of the shaft and an inner circumferential surface of the sleeve portion includes a radial dynamic pressure groove array defined therein; the sleeve portion includes a communicating hole defined therein, the communicating hole being arranged in communication with the gap; at least one tapered seal is arranged in communication with the gap, the at least one tapered seal including a first tapered seal through which oil feeding is possible; the gap, the communicating hole, and the at least one tapered seal include a lubricating oil arranged therein; the shaft and the sleeve portion are supported through the lubricating oil such that one of the shaft and the sleeve portion is rotatable with respect to the other; an opening angle 2×θs 1 of the first tapered seal is in a range of about 30 degrees inclusive to about 180 degrees exclusive; a tapered seal wall surface depth W 1 of the first tapered seal is 0.3 mm or more; and S < 2 ⁢ q 2 q 2 = D 1 · tan ⁢ ⁢ θ ⁢ ⁢ s 1 · cos ⁡ ( θ ⁢ ⁢ s 2 + β 2 ) sin ⁢ ⁢ θ ⁢ ⁢ s 2 · cos ⁡ ( θ ⁢ ⁢ s 1 + β 1 ) where S is an inside diameter of the largest imaginary circle inscribed in the communicating hole, β 1 is a contact angle between the lubricating oil and a wall surface of the first tapered seal, β 2 is a contact angle between the lubricating oil and a wall surface of the communicating hole, 2×θs 1 is the opening angle of the first tapered seal, 2×θs 2 is an angle defined between the wall surface of the communicating hole and a wall surface opposite an end portion of the communicating hole, D 1 is a tapered seal depth of the first tapered seal, and q 2 is a distance over which the lubricating oil has traveled beyond the wall surface of the communicating hole along the wall surface opposite the end portion of the communicating hole.