Rectangular Ultrasonic Motor Force and Stability
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Solution Overview
Problem
Ultrasonic motors with rectangular piezoelectric actuators face limitations in maximum force and mechanical performance due to restricted thickness, leading to unstable operation and increased production costs when multiple motors are connected in parallel.
Innovation Solution
An ultrasonic motor design featuring a rectangular piezoelectric plate with strategically arranged strip-shaped electrodes and generators, allowing for the simultaneous generation of acoustic standing waves along the length and thickness, which enables increased force and stability while reducing the need for multiple motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the piezoelectric plate is limited to B/4, then the motor structure is compact, but the maximum power and mechanical performance are reduced
Solution Approach 1:
The patent extends the friction contact length L beyond the thickness limitation B/4 by utilizing the length dimension of the piezoelectric plate. The friction element is positioned at one end of the plate, allowing the contact length to be determined by the plate length L rather than being constrained by thickness D, thus resolving the contradiction between compact structure and maximum power output.
2Force
If two or more motors are connected in parallel to increase maximum force, then the mechanical performance improves, but the operating frequency stability deteriorates
Solution Approach 1:
The patent combines multiple acoustic standing wave generators within a single ultrasonic motor unit. By integrating generators for both longitudinal and flexural acoustic standing waves into one motor, the system achieves increased maximum force while maintaining stable operating frequency, avoiding the frequency scattering problems that occur when multiple separate motors are connected in parallel.
3Force
If multiple motors are used to increase power output, then the maximum force increases, but the production cost increases
Solution Approach 1:
The patent integrates multiple acoustic standing wave generators into a single ultrasonic motor unit, combining the functions of what would otherwise require multiple separate motors. This integration reduces production costs by eliminating the need to manufacture, assemble, and maintain multiple separate motor units while still achieving the desired high force output.
4Power
If multiple motors are connected in parallel, then the power output increases, but the operational stability deteriorates due to frequency scattering
Solution Approach 1:
The patent merges multiple acoustic standing wave generators into a single integrated ultrasonic motor unit. This integration ensures that all generators operate at the same resonant frequency, eliminating the frequency scattering and operational instability that occur when multiple separate motors are connected in parallel, while still achieving high power output.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the maximum force and mechanical performance of ultrasonic motors, stabilizes their operation, and reduces production costs by allowing a single motor to replace multiple low-power motors, thus improving efficiency and cost-effectiveness.
Implementation Method 1
an ultrasonic actuator (1) in the form of a rectangular plate with a length L, a width B and a thickness D made of polarized piezoelectric material
Implementation Method 2
both flexural acoustic standing waves propagating along the length L and along the width B of the piezoelectric plate and longitudinal acoustic standing waves propagating along the length L are generated
Implementation Method 3
at least one friction element (3) pressed or pressed against the element (5) to be driven is arranged on the ultrasonic actuator
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Disclosed is an ultrasonic motor comprising: an ultrasonic actuator (1) in the form of a rectangular plate (2), consisting of piezoelectric material, with two main faces, two lateral faces, two end faces and at least one frictional element (3); a drivable element (5); and an electrical excitation device. The ultrasonic actuator has two or four generators for acoustic standing waves, the generators being arranged symmetrically with respect to a plane of symmetry (S) running perpendicularly to the lateral faces and parallel to the end faces of the actuator. The generators of the acoustic standing waves are provided as strip-type general-purpose electrodes and excitation electrodes alternating on one main face or on both main faces, the strip-type electrodes extending parallel to the plane of symmetry and the polarization directions of the materials between the electrodes running perpendicularly to said plane of symmetry. Also disclosed is an actuation method for the simultaneous excitation of flexural- and longitudinal standing waves.