Wall-Embedded Thermal Compensation in Vacuum Gauges
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Solution Overview
Problem
Existing thermal conductivity vacuum gauges face inaccuracies and durability issues due to the placement of thermal compensation elements on exterior or interior surfaces, which are affected by ambient temperature and process gases, respectively.
Innovation Solution
The thermal compensation element is enclosed within the wall of the gauge assembly, providing improved durability and accuracy by protecting it from external and internal environments, and allowing for modular and replaceable electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the thermal compensation element is placed on the exterior surface of the gauge assembly, then it can measure ambient temperature, but it is affected by environmental temperature and is easily damaged
Solution Approach 1:
The thermal compensation element is nested within the wall structure of the gauge assembly, specifically enclosed within a cavity formed in the wall. This nesting approach protects the element from external environmental damage while maintaining its temperature sensing function, resolving the contradiction between measurement accuracy and durability.
Solution Approach 2:
The wall cavity acts as an intermediary structure that houses the thermal compensation element. This intermediary provides both mechanical protection against damage and thermal coupling to the gauge body, allowing the element to measure the temperature of the gauge assembly accurately without being exposed to harmful external conditions.
2Reliability
If the thermal compensation element is placed on the interior surface of the gauge assembly, then it is protected from environmental damage, but it is affected by process gases and may be corroded
Solution Approach 1:
The thermal compensation element is nested within a cavity in the wall, positioned neither on the exterior nor interior surface. This nested configuration protects the element from both external environmental damage and internal process gas corrosion, while maintaining thermal coupling to the gauge assembly through the wall material.
Solution Approach 2:
The wall material and cavity structure serve as an intermediary barrier between the thermal compensation element and the process gases. This intermediary allows the element to sense the temperature of the gauge assembly without being directly exposed to corrosive gases, resolving the contradiction between durability and harmful factor exposure.
3Ease of manufacture
If the thermal compensation element is placed on the exterior surface, then installation is simple, but measurement accuracy is compromised due to environmental temperature effects
Solution Approach 1:
The cavity in the wall is designed to receive and house the thermal compensation element, providing a pre-formed installation location that maintains both manufacturing simplicity and measurement accuracy. The element is nested within this cavity, ensuring proper thermal coupling to the gauge assembly while protecting it from environmental temperature effects.
4Reliability
If the thermal compensation element is enclosed within the wall, then durability and measurement accuracy are improved, but device complexity increases
Solution Approach 1:
The cavity housing for the thermal compensation element is merged with the wall structure of the gauge assembly. This integration approach encloses the element within the wall without requiring separate housing structures or additional complex components, thereby improving durability while minimizing increases in device complexity.
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
This configuration enhances the durability and accuracy of gas pressure measurements by ensuring the thermal compensation element is less affected by external and internal factors, resulting in a more robust and accurate thermal conductivity vacuum gauge.
Implementation Method 1
The thermal compensation element is an element or component that measures the ambient temperature of the gauge itself... one way to implement this thermal compensation in a Pirani gauge is to include the thermal compensation element (e.g., a temperature-dependent resistor) as an arm in the same Wheatstone bridge circuit as the heater element
Implementation Method 2
As gas molecules collide with the heater element they will transfer (i.e., conduct) heat away from it... the pressure of the gas is measured as a function of its thermal conductivity
Data Source
AI summary
The present disclosure relates to a thermal conductivity vacuum gauge assembly. The assembly comprises a body defining an internal chamber for receiving working gas and a heater element disposed within the chamber. The body is defined by a wall having an outer facing wall surface and an opposing inner facing wall surface. A thermal compensation element is enclosed within the wall between the outer and inner facing wall surfaces. The present disclosure also relates to a thermal conductivity vacuum gauge including the assembly.