Ultrasonic Actuator Side Surface Friction Elements
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Solution Overview
Problem
Ultrasonic actuators with stick-slip drives suffer from parasitic movements and low driving force due to the counter-directional movement during the slip phase and limited forward movement during the stick phase.
Innovation Solution
An ultrasonic actuator made of polarized, piezoelectric material with triangular electrodes on opposing main surfaces and friction elements on side surfaces, generating an acoustic deformation standing wave for an elliptical movement that eliminates parasitic movements and enhances driving force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If friction elements are arranged on main surfaces for stick-slip drive, then the drive mechanism is realizable, but parasitic counter-directional movements occur and driving force is limited
Solution Approach 1:
The patent transitions the friction elements from moving on main surfaces (2D plane motion) to moving on side surfaces (1D linear motion along the thickness direction). This dimensional change eliminates the parasitic counter-directional movements inherent in stick-slip drives while maintaining the drive functionality through elliptical motion of the friction elements.
Solution Approach 2:
Instead of arranging friction elements on the large main surfaces as in conventional designs, the patent inverts the arrangement by placing them on the smaller side surfaces. This inversion fundamentally changes the motion characteristics from stick-slip with parasitic movements to pure elliptical motion without counter-directional displacement.
2Ease of operation
If friction elements move parallel to surface for stick-slip drive, then drive is realizable, but driving force remains relatively low
Solution Approach 1:
By moving friction elements from surface-parallel motion to side-surface motion along the thickness direction, the patent enables more effective force transmission. The elliptical motion trajectory on side surfaces allows for better utilization of friction forces, resulting in enhanced driving force compared to conventional stick-slip drives.
3Productivity
If stick-slip drive is used with friction elements on main surfaces, then the element to be driven moves during stick phase, but counter-directional movement occurs during slip phase reducing efficiency
Solution Approach 1:
The patent extracts and eliminates the harmful slip phase with counter-directional movement from the drive mechanism. By using elliptical motion of friction elements on side surfaces, the design achieves continuous unidirectional driving action without the energy-wasting backward movement characteristic of stick-slip drives.
Solution Approach 2:
The elliptical motion of friction elements on side surfaces enables continuous useful driving action without interruption by parasitic slip phases. The friction elements maintain effective contact and unidirectional force transmission throughout the motion cycle, eliminating energy loss associated with counter-directional movements.
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
The solution provides a more effective drive mechanism by eliminating counter-directional movements and increasing driving force, allowing for efficient movement of the element to be driven without parasitic motion.
Implementation Method 1
An ultrasonic actuator made of polarized, piezoelectric material with triangular electrodes on opposing main surfaces, generating an acoustic deformation standing wave
Data Source
AI summary
An ultrasonic actuator made of polarized piezoelectric material in the form of a single-layer or multilayer flat rectangular plate with two main faces, at least four lateral faces joining the main faces, and a thickness T, which is defined by the distance between the main faces in the direction of their surface normals, and wherein on both the one main face and the other opposite main face at least one layer including two triangular electrodes imposingly arranged and separated by a diagonal separating region, the electrodes on the one main face being offset relative to the electrodes on the other main face by 90°. The ultrasonic actuator is characterized in that on at least one of the lateral faces there are two mutually spaced friction elements designed to contact at least one element that is to be driven by the ultrasonic actuator.