Compact Ultrasonic Motor with Elastic Interlayer
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Solution Overview
Problem
Conventional ultrasonic motors with plate-shaped piezoelectric actuators face inefficiencies due to the use of flexible shafts as traction shafts, resulting in low traction force at high excitation voltages, and their large size limits miniaturization and application in precision mechanisms.
Innovation Solution
A compact ultrasonic motor design featuring multiple thin, plate-shaped piezoelectric actuators arranged closely with elastic holders, each actuator or pair assigned to an element to be driven, using an elastic intermediate layer for friction and an excitation device with power amplifiers connected to a control generator for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If multiple ultrasonic actuators are combined in parallel to increase traction force, then the traction force increases, but the motor dimensions become large
Solution Approach 1:
Multiple ultrasonic actuators are combined in a single integrated housing structure, merging their functions while maintaining compact dimensions. The actuators work together in parallel to generate high traction force without requiring separate motor units, thus resolving the contradiction between force multiplication and size increase.
Solution Approach 2:
The actuators are arranged in a nested or compact configuration within the housing, where components are space-efficiently organized. This allows multiple actuators to occupy minimal volume while still delivering combined traction force, addressing the contradiction between parallel actuator combination and compact motor dimensions.
2Force
If high excitation voltage is applied to increase traction force, then the traction force increases, but the device complexity and cost increase
Solution Approach 1:
The system operates at comparatively low excitation voltages by optimizing the actuator design and configuration. This parameter change from high to low voltage operation simplifies the excitation device requirements, reduces component complexity, and lowers overall system cost while maintaining adequate traction force through the combined action of multiple actuators.
3Reliability
If each ultrasonic actuator is housed separately to improve individual performance, then the actuator efficiency increases, but the ability to arrange multiple driven elements closely is lost
Solution Approach 1:
Multiple actuators and their housing structures are merged into a single integrated motor unit. This consolidation allows the driven elements to be arranged closely together in a compact configuration, maintaining both individual actuator performance and the ability to position multiple elements in close proximity for miniaturized applications.
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 design achieves high tensile forces with lower excitation voltage, increased efficiency, and compactness, allowing for independent movement of multiple elements while reducing production costs and enabling miniaturization.
Implementation Method 1
plate-shaped piezoelectric ultrasonic actuators
Implementation Method 2
work on the basis of acoustic bending and longitudinal waves
Implementation Method 3
work on the basis of acoustic bending and longitudinal waves
Implementation Method 4
each with at least one friction element arranged on them
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to an ultrasonic motor, comprising a large number of plate-shaped piezoelectric ultrasonic actuators (10), each having at least one friction element (18) arranged thereon, wherein an element (1) to be driven is associated with in each case one ultrasonic actuator or in each case one pair of ultrasonic actuators, and the ultrasonic motor furthermore has a housing and an electrical exciter device. According to the invention, the elements to be driven are moveable independently of one another, and each ultrasonic actuator or each ultrasonic actuator pair is arranged in a holder (2), wherein the holders are pressed against one another by means of housing side covers (3), and the friction elements of the ultrasonic actuators are pressed against a friction layer (50) of the corresponding element to be driven by means of an elastic interlayer (5), which is in contact with those peripheral faces of the ultrasonic actuators which are arranged opposite the friction elements, with the result that, overall, a cassette-like ultrasonic motor stack is produced.