Hub unit with steering function, steering system, and vehicle

A steering function-equipped hub unit for a steer-by-wire system in which a steering input section and a wheel are mechanically disconnected from each other, the steer-by-wire system being configured to steer the wheel, the steering function-equipped hub unit comprising:

• a hub unit main body including a hub bearing rotatably supporting the wheel and attachment shaft parts each having a trunnion shaft shape, the attachment shaft parts protruding upwardly and downwardly from an outer periphery of the hub bearing;
• a unit support member provided to a chassis frame component of a suspension device and rotatably supporting the hub unit main body about a turning axis extending in a vertical direction through the attachment shaft parts;
• and
• a steering actuator configured to rotationally drive the hub unit main body about the turning axis,
• wherein
• the upper and lower attachment shaft parts of the hub unit main body are supported by the unit support member through preloaded rolling bearings,
• the attachment shaft parts are arranged on an outer diametric side with respect to an outer race of the hub bearing,
• each of the attachment shaft parts is formed with an internal thread portion extending in a radial direction of the wheel, and
• a bolt screwed into the internal thread portion applies a pressing force to an end face of an inner race of a corresponding one of the preloaded rolling bearings through a pressing member interposed between the bolt and the end face of the inner race to preload the corresponding one of the preloaded rolling bearings.