Vibrating Element Apparatus Thermal Compensation
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Solution Overview
Problem
Existing vibrating element apparatuses, such as fluid level transducers, face issues with maintaining constant compressive force on piezoelectric elements when subjected to temperature changes, leading to potential malfunction or damage due to thermal expansion and contraction of the wall section.
Innovation Solution
Incorporating thermal compensation elements, such as aluminium-based plugs, that expand or contract at a similar rate to the support structure, ensuring a constant force is maintained on the piezoelectric stack across a wide temperature range (-70°C to +260°C, thereby stabilizing the vibration frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the wall section is made robust to provide stable mounting for the diaphragm and compression device, then the structural stability is improved, but the thermal expansion and contraction under temperature changes causes variable compressive force on the piezoelectric stack, leading to malfunction or damage
Solution Approach 1:
The patent applies thermal expansion principle by incorporating a compensation element made of material with different thermal expansion characteristics than the wall section. This compensation element is positioned between the compression device and the piezoelectric stack to offset the thermal effects. When the wall section expands or contracts with temperature changes, the compensation element undergoes corresponding dimensional changes that maintain a substantially constant compressive force on the piezoelectric stack, preventing both malfunction from insufficient compression and damage from excessive compression.
2Use of energy by moving object
If the diaphragm is made thin to reduce energy requirements for vibration, then the energy consumption is reduced, but the diaphragm becomes less robust and requires more complex support structures
Solution Approach 1:
The patent applies segmentation by separating the support function from the diaphragm itself. Instead of making the diaphragm robust (which would increase energy requirements), the patent introduces a separate compensation element and support structure system. The thin diaphragm is supported by the compensation element that is integrated with the wall section, dividing the structural support function from the vibratory function of the diaphragm.
Solution Approach 2:
The compensation element serves as an intermediary between the wall section and the piezoelectric stack/diaphragm assembly. It mediates the mechanical connection while compensating for thermal effects, allowing the diaphragm to remain thin and flexible for efficient vibration while still providing adequate structural support through the intermediary compensation mechanism.
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 allows the apparatus to operate reliably across a broad temperature range without compromising the compressive force on the piezoelectric elements, preventing malfunction and damage, and ensuring consistent performance.
Implementation Method 1
said thermal compensation element being selected and sized such that, when said apparatus is subjected to an increase in temperature, said at least one thermal compensation element expands to ensure a substantially constant force is maintained on the components comprising said stack
Implementation Method 2
a stack comprised of components which include one or more piezoelectric elements, said stack being positioned within said hollow body; and a compression device operable to compress said stack against the inner surface of said diaphragm
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention describes a vibrating element apparatus (10), preferably a tuning fork liquid level transducer, and a method of forming the same, which is particularly suitable form operation in environments subject to prolonged operation at markedly different temperatures. A piezoelectric stack (22), which generates vibration of the tines (17), is located within a hollow body (20) defined by a diaphragm (11), from which the tines (17) extend, and a wall section (12). Associated with the stack (22) are a pair of thermal compensating elements which expand or contract as the apparatus is subjected to differing temperatures. The thermal compensating elements (39,40) are selected and sized, having regard to the stack components, so that the stack and thermal compensating elements expand and contract to substantially the same amount as the structure in which the stack is supported.