Piezo Actuator Preload Wedge Mechanism
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Solution Overview
Problem
Existing wire clamps with piezoelectric actuators face issues with preload force stability due to loose screws from vibrations and insufficient friction, which can lead to damage from torque transmission during screw tightening.
Innovation Solution
A preload mechanism using wedges with inclined surfaces that are slidable over mating inclined surfaces, allowing for a transverse force application to achieve a stable preload force along the longitudinal axis of the actuator, with self-locking behavior to maintain consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a set screw and preload block are used to apply preload force to the piezoelectric actuator, then the actuator can be preloaded along its longitudinal axis, but the screw may become loose due to vibration or insufficient friction, resulting in decrease of preload force
Solution Approach 1:
The invention introduces a wedge-shaped preload block with inclined surfaces that converts transverse adjustment forces into longitudinal preload forces through mechanical advantage. The wedge geometry transforms the direction of force application, allowing stable preload application without relying on friction between the screw and block surfaces.
Solution Approach 2:
The invention replaces the traditional screw-thread friction-based preload mechanism with a wedge-based mechanical advantage system. This substitution eliminates the loosening problem inherent in friction-dependent connections while maintaining the ability to apply and adjust preload forces on the piezoelectric actuator.
2Force
If a set screw is used to apply preload force, then the actuator can be preloaded, but torque will be transmitted to the piezo stack as the screw is tightened, which may damage the piezo stack
Solution Approach 1:
The invention extracts the torque transmission path from the preload application mechanism. By using a wedge-shaped block that contacts the actuator through inclined surfaces, the design separates the adjustment function from the force transmission function, preventing torque from being transmitted to the piezoelectric stack during preload application.
Solution Approach 2:
The wedge-shaped preload block acts as an intermediary element between the adjustment screw and the piezoelectric actuator. This intermediate component transforms the rotational motion of the screw into linear motion of the wedge, which then applies the preload force without transmitting torque to the actuator stack.
3Ease of operation
If external force is repeatedly applied to the preloading screw in the axial direction, then adjustment can be made, but the screw may loosen due to vibration or insufficient friction
Solution Approach 1:
The wedge-shaped preload block converts axial forces applied during adjustment into transverse forces that are resolved through the inclined surfaces, creating a self-locking effect. This dimensional transformation ensures that repeated axial adjustments do not cause loosening, as the wedge geometry naturally resists reverse motion.
Solution Approach 2:
The invention converts the potentially harmful effect of vibration and repeated adjustment forces into a beneficial self-locking mechanism. The wedge geometry transforms these dynamic forces into enhanced contact pressure between the inclined surfaces, preventing loosening rather than causing it.
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 stable and consistent preload force to the piezoelectric actuator, reducing the risk of damage and improving the performance of the wire clamp by eliminating the issues of loose screws and torque transmission.
Implementation Method 1
a piezoelectric actuator having a longitudinal axis extending between a first end and a second end
Implementation Method 2
the preload mechanism comprises at least one wedge having an inclined surface which is slidable over a mating inclined surface
Data Source
AI summary
A wire clamp includes a clamp body; a pair of arms coupled to the clamp body; and a piezoelectric actuator having a longitudinal axis extending between a first end and a second end, the actuator being coupled to the pair of arms at the first end and to the clamp body at the second end. The second end of the actuator is coupled to the clamp body by a preload mechanism for applying a preload force along the longitudinal axis, and the preload mechanism comprises at least one wedge having an inclined surface which is slidable over a mating inclined surface.