Patent ID: 7686516

Claim:
A rolling bearing unit comprising: a rolling bearing unit including a stationary side raceway ring not rotated in a state of use, a rotary side raceway ring rotated in a state of use, and a plurality of rolling elements provided between a stationary side raceway and a rotary side raceway, which exist on mutually opposing peripheral surfaces of the stationary side raceway ring and the rotary side raceway ring; and a load measuring unit including an encoder which is supported on a part of the rotary side raceway ring concentrically with the rotary side raceway ring and a characteristic of a sensed surface of which is changed alternately along a circumferential direction, at least one sensor which is supported on a non-rotated portion in a state that a sensing portion of the at least one sensor is opposed to the sensed surface and an output signal of which is changed in response to a change in characteristic of the sensed surface, and an arithmetic unit for calculating a load applied between the stationary side raceway ring and the rotary side raceway ring based on the output signal, wherein a pitch or phase through which the characteristic of the sensed surface is changed along the circumferential direction is changed continuously in response to an acting direction of a to-be-sensed load, and the arithmetic unit has a function of calculating the load based on a pattern according to which the output signal of the at least one sensor is changed, and wherein the to-be-sensed load is a radial load that acts between the stationary side raceway ring and the rotary side raceway ring in a radial direction, the sensed surface includes a side surface of the encoder in an axial direction, a first sensed portion and a second sensed portion having different characteristics mutually are aligned alternately on the sensed surface at an equal interval in the circumferential direction, and a width of the first sensed portion in the circumferential direction is widened toward an outer side in the radial direction and a width of the second sensed portion in the circumferential direction is widened toward an inner side in the radial direction.