Hub unit with sensor
A sensor device including a resolver having a rotor provided on a rotation-side raceway member of a hub unit and a stator provided on a stationary-side raceway member of the unit, and a processing circuit for processing a signal to be output in accordance with an air gap between the stator and the rotor. The processing circuit has a wheel ground contact load calculating unit for determining the ground contact load on a wheel from the air gap between the stator and the rotor.
1. A sensor-equipped hub unit comprising a hub unit having a rotation-side raceway member to be provided with a wheel, a stationary-side raceway member to be fixed to a vehicle body and rolling bodies arranged between the two raceway members, and a sensor device mounted on the hub unit,
the sensor-equipped hub unit being characterized in that the sensor device comprises a resolver composed of a rotor provided on the rotation-side raceway member and a stator provided on the stationary side raceway member, and a processing circuit for processing a signal to be output in accordance with an air gap between the stator and the rotor, the processing circuit having a wheel ground contact load calculating unit for determining the ground contact load on the wheel from the air gap between the stator and the rotor.
2. A sensor-equipped hub unit according to claim 1 wherein the processing circuit further has a rotation detecting unit for obtaining data as to the rotation of the wheel from the air gap between the stator and the rotor.
3. A sensor-equipped hub unit according to claim 1 wherein the stator comprises an annular core having a saw-toothed inner periphery, and a stator winding formed by providing coils respectively on all teeth of the core, the stator being fixed to an inner periphery of the stationary-side raceway member by a press fit with inner ends of teeth of the core facing radially inward.
4. A sensor-equipped hub unit according to claim 3 wherein the rotor is provided by machining the rotation-side raceway member at a portion thereof opposed to the stator for use as a rotor.
5. A sensor-equipped hub unit according to claim 3 wherein the rotor is provided by fittingly fixing an annular magnetic body having a cylindrical inner peripheral surface and a noncylindrical outer peripheral surface to the rotation-side raceway member at a portion thereof opposed to the stator.
6. A sensor-equipped hub unit according to claim 1 wherein the rotation-side raceway member comprises a shaft composes of a large-diameter portion having a first raceway and a small-diameter portion having an outside diameter smaller than the diameter of the first raceway, and a ring having a second raceway and fitted around the small-diameter portion of the shaft, the ring being fastened to the shaft with a nut screwed on an externally threaded end portion of the small-diameter portion of the shaft.
7. A sensor-equipped hub unit according to claim 6 wherein the resolver is provided at an end portion of the stationary-side raceway member, the stator being forced into an end portion of the rotation-side raceway member by a press fit, the rotor being formed by interposing between the nut and the ring an annular body providing a rotor.
8. A sensor-equipped hub unit according to claim 6 wherein the resolver is provided at an end portion of the stationary-side raceway member, the stator being forced into an end portion of the rotation-side raceway member by a press fit, the rotor being provided by forming a flange portion for making a rotor integrally with the nut.
9. A sensor-equipped hub unit according to claim 6 wherein the resolver is provided on the stationary-side raceway member at an intermediate portion thereof between two rows of rolling bodies, and the stator is forced into a midportion of the rotation-side raceway member by a press fit, the rotor being provided by shaping an outer periphery of the shaft of the rotation-side raceway member in a specified form.
10. A sensor-equipped hub unit according to claim 1 wherein the resolver is a VR-type resolver.
11. A sensor-equipped hub unit according to claim 1 wherein a surface of the rotor to be detected is in the form of a cylindrical surface which is eccentric with respect to a cylindrical surface centered about an axis of the hub unit.
12. A sensor-equipped hub unit according to claim 1 wherein a surface of the rotor to be detected is in the form of a cylindrical surface having a cutout.