Piezoelectric Rotary Drive Leaf Spring Preloading
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Solution Overview
Problem
The production and assembly of existing piezoelectric rotary drives with spring clips are complex, leading to settling phenomena that result in reduced contact pressure and undefined preloading forces, due to tolerances and complex shaping requirements.
Innovation Solution
A piezoelectric rotary drive utilizing a simple and inexpensive leaf spring as the loading means, which is clamped between retaining sections and applies a preloading force, allowing for higher preloading forces and simplified assembly, and enabling the use of brittle materials for increased mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a spring clip with complex shaping and bending points is used, then the loading means can apply preloading force, but the production and assembly become complex and settling phenomena occur over time
Solution Approach 1:
The loading means is divided into multiple leaf springs instead of using a single complex spring clip. Each leaf spring can be produced separately with simple geometry and then assembled, reducing the complexity of individual components while maintaining the overall preloading function
Solution Approach 2:
Instead of using a preformed or deformed spring that encompasses half the circumference, the invention uses flat leaf springs that are clamped between retaining sections. This inverts the conventional approach by using simple flat elements rather than complex pre-formed springs, eliminating the need for guiding the loading means around the shaft and frame
2Force
If a spring clip with considerable length and bending points is used, then preloading force can be applied, but tolerances in bending lead to undefined contact pressure and preloading force
Solution Approach 1:
The loading means is segmented into multiple leaf springs with standardized, simple geometries. This segmentation allows for tighter manufacturing tolerances on each individual leaf spring compared to a single long spring clip, resulting in more defined and predictable contact pressure and preloading force
Solution Approach 2:
The invention changes the geometric parameters of the loading means from a single long spring with multiple bending points to multiple shorter leaf springs with simple geometries. This parameter change reduces the accumulation of tolerances and leads to more precise and defined contact pressure
3Reliability
If a preformed spring encompassing half the circumference is used, then the loading means can function, but the production process becomes complex and time-consuming
Solution Approach 1:
The loading means is segmented into multiple leaf springs that can be produced independently using simple manufacturing processes such as cutting and bending flat stock. This segmentation dramatically increases production efficiency compared to forming a single complex spring clip, while the assembled structure maintains functional reliability
Solution Approach 2:
The invention uses simple flat leaf springs that can be produced inexpensively and quickly, replacing expensive and time-consuming preformed springs. The simplified geometry allows for easier manufacturing and assembly, improving productivity while maintaining the necessary functional reliability
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 efficient and cost-effective production process with higher preloading forces, improved assembly simplicity, and the ability to use materials suitable for harsh environments, such as high-purity vacuum or strong magnetic fields, by maintaining material stress uniformity and avoiding plastic deformation.
Implementation Method 1
the loading means is designed as a leaf spring which in the relaxed state extends substantially in a plane
Implementation Method 2
at least one piezoelectric actuator
Implementation Method 3
a coupling section that can be coupled to the shaft in a force-fit manner in order to accomplish a stick-slip drive
Data Source
AI summary
Disclosed is a piezoelectric rotary drive for a shaft, which includes a piezoelectric actuator, a deformable frame that can be coupled with a coupling section to the shaft in a force-fit manner in order to accomplish a stick-slip drive, and a loading device which can apply a preloading force to the coupling section and/or the actuator and/or the shaft. To facilitate production and assembly, the loading device can be a leaf spring which in the relaxed state extends substantially in a plane, such as along a straight line.