Temperature Compensated Bellows for Capillary Indicators
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Solution Overview
Problem
Existing bellows systems for storing and dispensing fluids in capillary tubes fail to provide reliable and consistent fluid indication across a wide range of operating temperatures due to thermal expansion, leading to inaccuracies in fluid meniscus position.
Innovation Solution
A temperature-compensated bellows system is designed with a flexible, watertight housing and a miniature bellows and reservoir containing a second fluid with a selected coefficient of expansion, which compensates for the thermal expansion of the first fluid, maintaining accurate fluid indication across a large temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single fluid is used in a capillary tube for indication, then the arrangement is simple, but the indication accuracy deteriorates under wide temperature fluctuations due to thermal expansion
Solution Approach 1:
The patent introduces a second compensating fluid with a known coefficient of thermal expansion in a miniature bellows. This compensating fluid expands or contracts in response to temperature changes, creating pressure variations that counteract the thermal expansion effects on the first indication fluid. By carefully selecting the coefficient of expansion of the second fluid, the system compensates for temperature-induced volume changes in the first fluid, maintaining accurate meniscus positioning in the capillary tube across wide temperature ranges while preserving the simplicity of using a single indication fluid.
2Volume of moving object
If the bellows storage volume is reduced to compact the design, then the device size decreases, but the fluid storage capacity is reduced
Solution Approach 1:
The patent places the miniature compensating bellows and reservoir assembly inside the larger principal bellows housing. The second fluid's bellows structure is nested within the volume defined by the first fluid's bellows, allowing both fluid storage systems to coexist in a compact configuration. This nested arrangement enables the main bellows to maintain adequate fluid storage capacity while the internal compensating bellows occupies only the space necessary for temperature compensation, achieving both compact overall size and sufficient fluid capacity.
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 system ensures consistent and accurate fluid indication by counteracting thermal expansion effects, allowing for reliable operation from -20 to 70 degrees Celsius, thereby simplifying the mechanism and increasing accuracy.
Implementation Method 1
a temperature compensation device is disposed... made up of a miniature bellows and reservoir in which a second fluid is placed having a coefficient of expansion which may be the same as or different than the first fluid. The device is arranged to allow expansion of the second fluid to negatively affect or compensate the displacement of the first fluid due to thermal expansion thereof in the capillary tube.
Data Source
AI summary
A temperature compensated bellows is provided for storage and displacement of a first fluid used as an indicator in a capillary tube. The bellows is made of a housing made of flexible, watertight material. The housing is made up of an upper portion, a lower portion, and an outer accordion formed portion. The accordion formed portion has a length/and is sealingly connected along a periphery between the upper and lower portions. At least one entry/exit port formed on at least one of the portions thereof. At least one of the upper and lower portions extends from a periphery of the accordion formed portion substantially within the housing so as to reduce the storage volume. Preferably, within this area defined by the portion which extends within the housing, a temperature compensation device is disposed. This device is made up of a miniature bellows and reservoir in which a second fluid is placed having a coefficient of expansion which is different than the first fluid. The device is arranged to allow expansion of the second fluid to negatively affect the displacement of the first fluid in the capillary tube. In this manner, the appropriate selection of a first and second fluid allows for temperature compensation, so as to yield an indication which is consistent and accurate across a large range of temperatures.