Abstract: The present disclosure relates generally to a permanent magnet, brushless motor comprising a primary rotor having alternating magnetic poles around a circumference, a secondary rotor similar to the primary rotor. The primary rotor may be free to rotate by approximately plus or minus one pole of the secondary rotor. As such, when the two rotor components have opposite polarities aligned, the motor may be in a field weakened state. Generally, the field weakened state may be the normal state of the motor. As a significant load is encountered, the rotors may automatically transition to a non-weakened state wherein similar polarities are aligned on the rotors. A permanent magnet, brushless motor as described herein may be employed at a motor level or integrated into a linear actuator, wherein the rotor of the permanent magnet, brushless motor may include a hollow shaft.

Abstract: The present disclosure relates generally to a permanent magnet, brushless motor comprising a primary rotor having alternating magnetic poles around a circumference, a secondary rotor similar to the primary rotor. The primary rotor may be free to rotate by approximately plus or minus one pole of the secondary rotor. As such, when the two rotor components have opposite polarities aligned, the motor may be in a field weakened state. Generally, the field weakened state may be the normal state of the motor. As a significant load is encountered, the rotors may automatically transition to a non-weakened state wherein similar polarities are aligned on the rotors. A permanent magnet, brushless motor as described herein may be employed at a motor level or integrated into a linear actuator, wherein the rotor of the permanent magnet, brushless motor may include a hollow shaft.

Abstract: A friction stir weld apparatus having a linear drive actuator and a separate friction stir weld device. The linear actuator and the friction stir weld device are driven by concentric motors. In the preferred embodiment, the thrust member of the actuator is connected to the friction stir weld device within or adjacent to the friction stir weld device motor to advance and retract the friction stir weld deice along a linear axis concentric with the actuator and friction stir weld device motors.