Piezo Stack Drive Cylindrical Sleeve Fastening
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Solution Overview
Problem
Existing piezo stack drives in vibration sensors face challenges with high-temperature applications and require thicker membranes for secure fastening, which contradicts the need for thin membranes to reduce energy consumption and maintain pre-load, leading to inefficiencies and potential loss of drive output.
Innovation Solution
A cylindrical sleeve assembly arrangement with a circumferential flange and anti-rotation lock for secure fastening of the drive unit to the membrane, eliminating the need for a central tension bolt and allowing operation under compression, thereby reducing membrane thickness and enhancing drive efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a piezo stack drive is clamped against the membrane using a single-piece clamping bolt mated against the membrane, then secure fastening and effective vibration transfer are achieved, but the membrane must be formed relatively thick to create a fastening point, which increases energy consumption and contradicts the requirement for thin membranes
Solution Approach 1:
The patent introduces an intermediate assembly arrangement (sleeve with flange) that mediates between the drive unit and the membrane. This intermediary component provides a secure fastening point for the clamping bolt without requiring the membrane itself to be thick, thereby resolving the contradiction between secure fastening and thin membrane requirements
Solution Approach 2:
The fastening system is segmented into separate functional components: the sleeve provides structural support and fastening points, the flange provides the clamping surface, and the membrane maintains its thin profile. This segmentation allows each component to be optimized independently, enabling secure fastening without thickening the membrane
2Device complexity
If the piezo stack drive is mounted and pre-loaded only in the vibration sensor assembly, then the structure is simple, but the drive cannot be pre-assembled, tempered, or pre-tested, leading to loss of pre-load and requiring re-tempering of the entire sensor
Solution Approach 1:
The assembly arrangement enables preliminary actions (pre-assembly, tempering, pre-testing) to be performed on the drive unit before final installation in the sensor. The standardized interface allows the drive to be prepared in advance, and the assembly arrangement ensures that pre-load is maintained during operation, preventing the need for re-tempering
Solution Approach 2:
The assembly arrangement serves multiple functions: it provides a standardized mounting interface that works with different drive units, enables pre-assembly and tempering operations, ensures stable pre-load transmission, and facilitates modular replacement. This multi-functionality resolves the contradiction between simple structure and reliable pre-load stability
3Ease of manufacture
If a multi-segmented piezo element is glued onto the membrane, then the structure is simple and easy to manufacture, but the drive generates only limited stroke and cannot be used at temperatures above the glass transition temperature of the adhesive and below the Curie temperature of the piezo material
Solution Approach 1:
The patent replaces the adhesive-bonded multi-segmented piezo element with a mechanically clamped piezo stack drive. The clamping mechanism provides secure mechanical attachment without relying on adhesive bonds, thereby eliminating the glass transition temperature limitation while maintaining manufacturing simplicity through standardized assembly procedures
Solution Approach 2:
The assembly arrangement uses composite construction with the sleeve, flange, and clamping components made from materials suitable for high-temperature applications. This composite approach allows the drive assembly to withstand temperatures above 150°C while maintaining structural integrity and simple assembly characteristics
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 enables secure fastening and efficient vibration transfer while reducing membrane thickness, preventing pre-load loss and improving drive output at higher temperatures, thus addressing the limitations of existing piezo stack drives.
Implementation Method 1
By applying an electrical voltage to the piezo elements, the latter change their expansion in axial direction of the bolt, thus causing the membrane to vibrate
Implementation Method 2
The ceramic adjustment elements 17 serve to adjust a thermal expansion coefficient between the piezo elements 15 and the compression elements 19
Data Source
AI summary
An assembly arrangement for connecting a membrane of a vibration sensor with a drive unit such that vibrations of the drive unit are transmitted to the membrane and vibrations of the membrane are transferred to the drive unit, wherein the assembly arrangement is formed as a cylindrical sleeve, having on one end a fastening section for indirectly or directly fastening to the membrane or an element connected with the membrane, and an insertion opening for the drive unit on the other end.