PI Ceramic offers piezoelectric rotary motors.

For Piezo Linear Motor Systems (Ultrasonic Piezo Motor / Piezo Stepping Motor) click here.

White Papers on Piezo Motor Design

Rotary Piezo Motors are classified as ultrasonic motors with ring-shaped resonator. The main components - with exception of the resonator - consist of special plastics, and they are manufactured by injection moulding processes. They are characterized by a simple construction, a low speed at a relatively high torque, small weight, and a small flat structural form. For the operation of the piezo motor various control devices have been developed for different power supplys. Figure 1 shows the motor type PMR 40.08 with control electronic and its piezo resonator.

As an active element the piezo motor is based on a radially vibrating piezoresonator. The frequency depends on the diameter D of the piezo ring and on the frequency constant N of the piezo ceramic; its amount for the PMR 40.08 is approximately 52 kHz. On the edge of the cylinder of the resonator laminas of spring steel are mounted. These laminas are excited by the piezoresonator to lengthwise vibrations, and by the kind of arrangement to flexural vibrations. Both components of these movements superpose themselves in an elliptic motion. Part 1 is the baseplate, part 2 piezo resonator and part 3 the rotor.


Figure 3 demonstrates the modes of vibration of a lamina. The elliptic movement of the tip of the lamina is divided into two ranges.

Range AB - expansion of the resonator: The free tip of the lamina is pressed to the friction surface of the rotor; by those means a kind of frictional toothing is originated between the tip of the lamina and the friction surface of the rotor. By this toothing the mechanical power is transferred to the rotor.

Range BA - contraction of the resonator
At range BA the free tip of the lamina loosens from the friction surface of the rotor, and so the rotor rotates without any losses due to friction.