Patent ID: 8686603

Claim:
A linear and rotary actuator comprising: a spline shaft having a rolling-element rolling part extending in an axial direction; a hollow rotor that surrounds the spline shaft; a stator of a rotary motor in which a space for holding the rotor is formed and which is configured to rotate the rotor around an axis line; a spline nut which rotates together with the rotor to transmit rotation of the rotor to the spline shaft and accepts linear movement of the spline shaft in the axial direction; a mover shaft of a linear motor connected to the spline shaft; and a stator of the linear motor for moving the mover shaft of the linear motor linearly in the axial direction, wherein the spline nut has a rolling-element circulation passage including a loaded rolling-element rolling part facing the rolling-element rolling part of the spline shaft and a plurality of rolling elements arranged in the rolling-element circulation passage, the spline nut, the stator of the rotary motor and the stator of the linear motor are arranged in this order from an end of the mover shaft and the spline shaft in the axial direction, the rotor comprises a main part that is rotated by the stator of the rotary motor, a spline-nut one-end holding part that is connected to the main part and is configured to hold one end of the spline nut in the axial direction, and a spline-nut opposite-end holding part that is configured to hold an opposite end of the spline nut in the axial direction, the main part of the rotor has a diameter that is smaller than that of the spline-nut one-end holding part, plural permanent magnets are attached in an outer peripheral surface of the main part of the rotor, the spline nut and the stator of the rotary motor are arranged apart in an axial direction, the spline-nut opposite-end holding part comprises a large-diameter part and a small-diameter part of different diameters, a bearing fits outside the small-diameter part to rotatably support the spline-nut opposite-end holding part, and the spline nut and the bearing are arranged apart in an axial direction.