Rolling bearing, bearing unit for air turbine, and air turbine handpiece for dental use

1. A bearing unit for an air turbine comprising:

a turbine blade configured to rotate with receiving compressed air;

a rotary shaft having the turbine blade integrally fixed thereto and capable of mounting a tool thereto; and

a rolling bearing configured to rotatably support the rotary shaft to a housing,

wherein the rolling bearing comprises:

an outer ring fixed to the housing;

an inner ring fixed to the rotary shaft;

a plurality of rolling elements rollably arranged between the outer ring and the inner ring; and

a seal member fixed to an inner peripheral surface of the outer ring and configured to seal a bearing internal space between the outer ring and the inner ring,

wherein an axial end, which is positioned at a downstream side with respect to a supply direction of the compressed air, of an outer peripheral surface of the inner ring has a flat and inclined surface having a diameter that changes from large to small toward the downstream side with respect to the supply direction of axial compressed air,

wherein the seal member is configured only by an elastic material without a metal core, and has a base part extending in a radial direction and a lip part extending from a radially inner end of the base part and inclined to the downstream side with respect to the supply direction of the compressed air toward a radially inner side,

wherein when the compressed air is not applied, an inclined surface, which is positioned at an upstream side with respect to the supply direction of the compressed air, of the lip part of the seal member is in surface contact with the inclined surface of the inner ring,

wherein when the compressed air is applied, a contact area between the inclined surface, which is positioned at the upstream side with respect to the supply direction of the compressed air, of the lip part of the seal member and the inclined surface of the inner ring becomes smaller, as compared to when the compressed air is not applied,

wherein the lip is inclined before the seal member is fixed to the outer ring,

wherein a groove portion is formed in the inner peripheral surface of the outer ring, and the groove portion has:

a tapered surface inclined to a radially outer side toward an axially inner side; and

an axially inner surface with which an axial side surface of the base part is in contact at a more axially inner side than the tapered surface, and

wherein only the base part of the seal member and a snap ring are interposed and fixed between the tapered surface and the axially inner surface.

2. A bearing unit for an air turbine comprising:

a turbine blade configured to rotate with receiving compressed air;

a rotary shaft having the turbine blade integrally fixed thereto and capable of mounting a tool thereto; and

a rolling bearing configured to rotatably support the rotary shaft to a housing,

wherein the rolling bearing comprises:

an outer ring fixed to the housing;

an inner ring fixed to the rotary shaft;

a plurality of rolling elements rollably arranged between the outer ring and the inner ring; and

a seal member fixed to an inner peripheral surface of the outer ring and configured to seal a bearing internal space between the outer ring and the inner ring,

wherein at least a part, with which a lip part is in contact, of an outer peripheral surface of the inner ring is configured as a flat cylindrical surface along an axial direction,

wherein the seal member is configured only by an elastic material without a metal core, and has a base part extending in a radial direction and the lip part extending from a radially inner end of the base part and inclined to a downstream side with respect to a supply direction of the compressed air toward a radially inner side,

wherein when the compressed air is not applied, an inner peripheral surface of the lip part of the seal member is in contact with the cylindrical surface of the inner ring,

wherein when the compressed air is applied, a contact area between the inner peripheral surface of the lip part of the seal member and the cylindrical surface of the inner ring becomes smaller, as compared to when the compressed air is not applied,

wherein the lip is inclined before the seal member is fixed to the outer ring,

wherein a groove portion is formed in the inner peripheral surface of the outer ring, and the groove portion has:

a tapered surface inclined to a radially outer side toward an axially inner side; and

an axially inner surface with which an axial side surface of the base part is in contact at a more axially inner side than the tapered surface, and

wherein only the base part of the seal member and a snap ring are interposed and fixed between the tapered surface and the axially inner surface.

3. The bearing unit for an air turbine according to claim 1 ,

wherein when the compressed air is applied, the seal member is not in contact with the outer peripheral surface of the inner ring.

4. An air turbine handpiece for dental use comprising the bearing unit for an air turbine according to claim 1 .

5. The bearing unit for an air turbine according to claim 2 ,

wherein when the compressed air is applied, the seal member is not in contact with the outer peripheral surface of the inner ring.

6. An air turbine handpiece for dental use comprising the bearing unit for an air turbine according to claim 2 .

7. An air turbine handpiece for dental use comprising the bearing unit for an air turbine according to claim 3 .

8. An air turbine handpiece for dental use comprising the bearing unit for an air turbine according to claim 5 .