Piezoelectric Actuator Asymmetric Surface Design
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Solution Overview
Problem
Piezoelectric actuators experience significant energy losses due to internal and external friction, leading to reduced oscillation speed and efficiency, as well as decreased operational reliability due to heating caused by friction.
Innovation Solution
The actuator is designed with a second lateral surface area of length greater than the acoustic standing wave wavelength but not equal to a multiple of half the wavelength, creating a non-resonant region with reduced oscillation amplitude, thereby minimizing mechanical losses and heating, and allowing for direct connection to a bridge power amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the actuator uses a symmetric design with friction elements on one lateral surface, then the actuator can generate acoustic standing waves for driving elements, but internal friction causes symmetric heating and significant energy losses
Solution Approach 1:
The patent applies asymmetry by making the second lateral surface area have a length B that is not equal to a multiple of half the wavelength, creating a non-resonant surface. This asymmetric design causes material points on the second lateral surface to have lower oscillation amplitudes compared to the resonant first lateral surface, thereby reducing internal friction and energy losses while maintaining acoustic wave generation capability.
2Speed
If the actuator operates at resonant frequency for maximum oscillation speed, then the speed of movement of driven elements increases, but external friction at mounting points generates additional heat and reduces reliability
Solution Approach 1:
The asymmetric design of the second lateral surface area creates regions of lower oscillation amplitude where mounting points can be located. This reduces external friction at attachment points during high-speed operation, minimizing heat generation and improving operational reliability while maintaining resonant oscillation speed for driving elements.
3Ease of manufacture
If the actuator uses a conventional symmetric design, then manufacturing is simplified, but mechanical losses from friction reduce overall efficiency
Solution Approach 1:
The patent applies local quality by creating a specific geometric configuration where only the second lateral surface area has the non-resonant length property. This localized asymmetric feature can be integrated into otherwise conventional actuator designs, maintaining ease of manufacture while significantly reducing mechanical losses and improving driving efficiency through reduced friction in specific regions.
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 reduces mechanical losses, increases oscillation speed, enhances efficiency, and improves operational reliability by minimizing friction-related heating and simplifying the electrical excitation system.
Implementation Method 1
The invention relates to an actuator, preferably a piezoelectric actuator... comprising at least two generators for exciting an acoustic standing wave in the actuator
Implementation Method 2
an acoustic wave whose length corresponds to the length L of the first lateral surface area propagates along the first lateral surface area or at its surface (resonant surface)
Implementation Method 3
considerable energy losses occur in the actuator due to internal friction... external friction develops at the points at which the actuator is supported from the outside... additional heat that is introduced at least partially into the actuator
Data Source
AI summary
An exemplary actuator in the form of a plate is disclosed, which includes, at least two generators for exciting an acoustic standing wave in the actuator. The actuator can have at least two main surfaces and a plane of symmetry S running perpendicularly to the main surfaces, with respect to which the generators are arranged symmetrically. A first lateral surface area can have a length L that substantially corresponds to the wavelength of the acoustic standing wave excited in the actuator. A second lateral surface area of the actuator can have a length (B) that is greater than the wavelength of the acoustic standing wave excited in the actuator, and that is not equal to a multiple of half the wavelength of the excited acoustic standing wave.