Patent ID: 7997804

Claim:
A rolling bearing apparatus comprising: rolling elements; an outer ring including a raceway surface formed at an inner periphery thereof and comprising a first linear expansion coefficient, the rolling elements rolling on the raceway surface, the raceway surface receiving from the rolling elements a radial load and a load directed toward one side in an axial direction; an inner ring including a raceway surface formed at an outer periphery thereof, the rolling elements rolling on the raceway surface of the inner ring, the inner ring being incorporated in the outer ring through the rolling elements in a preload-applied condition; a housing in which an outer peripheral surface of the outer ring is fitted such that the outer ring can be moved in the axial direction, the housing comprising a second linear expansion coefficient larger than the first linear expansion coefficient; a rotation shaft which is fitted in an inner peripheral surface of the inner ring, and comprises a third linear expansion coefficient smaller than the second linear expansion coefficient; a pressure chamber formed as a sealable space between the housing and an end portion of the outer ring at one side in the axial direction; and a preload holding unit that applies a fluid pressure to the pressure chamber to move the outer ring toward the other side in the axial direction to suppress decrease of the preload due to thermal expansion of the housing, wherein the preload holding unit includes: a pressure source connected to the pressure chamber via a fluid supply passage; a check valve which is provided at a portion of the fluid supply passage disposed between the pressure chamber and the pressure source, and allows a fluid to flow into the pressure chamber if a pressure of the fluid is higher than a first set pressure; a relief valve provided at a discharge passage so as to discharge the fluid from the pressure chamber if the pressure in the pressure chamber becomes higher than a second set pressure which is higher than the first set pressure and to close the discharge passage if the pressure in the chamber is lower than or equal to the second set pressure; and a fluid supply control portion which supplies the fluid to the pressure chamber from the pressure source via the check valve if the pressure within the pressure chamber becomes lower than the first set pressure, and stops the supply of the fluid from the pressure source when the pressure within the pressure chamber becomes larger than a third set pressure which is higher than the first set pressure but is lower than the second set pressure.