Automotive Gas Sensor Thermal Isolation via Bonding Wires
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Solution Overview
Problem
Existing gas sensors for automotive applications face challenges in thermally decoupling housing components from the sensor element, leading to complex structures and assembly difficulties, as well as potential heat transfer issues affecting other electronic parts.
Innovation Solution
A gas sensor design featuring a housing with a lower part and an upper part, where the sensor element hangs from connecting wires, allowing for a tool arm to insert through an assembly opening in the lower part for mounting, and the upper part closes this opening, creating a thermally isolated measuring chamber with platinum-sheathed wires and a gas-permeable but liquid-impermeable closure element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the sensor element is thermally isolated from the housing, then heat transfer to other components is reduced, but the structural complexity increases due to additional thermal insulation components
Solution Approach 1:
The patent introduces bonding wires as intermediary elements that serve dual functions: electrical connection and thermal insulation. These wires act as mediators between the sensor element and housing, allowing electrical signal transmission while minimizing heat transfer. The bonding wires are specifically designed with materials having low thermal conductivity, thus resolving the contradiction by providing thermal isolation without requiring additional complex insulation structures.
Solution Approach 2:
The bonding wires perform multiple functions simultaneously: they provide electrical connection for the sensor element and serve as thermal insulation barriers. This multi-functionality eliminates the need for separate thermal insulation components, thereby reducing structural complexity while achieving effective heat isolation from other housing components.
2Ease of manufacture
If the housing structure is simplified, then manufacturing cost is reduced, but thermal isolation performance deteriorates
Solution Approach 1:
The bonding wires are designed to perform both electrical connection and thermal insulation functions simultaneously. This eliminates the need for separate, complex thermal insulation structures, thereby simplifying the housing design and reducing manufacturing costs while maintaining effective thermal isolation performance.
Solution Approach 2:
The patent extracts the thermal insulation function from the housing structure itself and transfers it to the bonding wires. By removing the requirement for thermally insulating housing materials or additional insulation layers, the housing can be manufactured more simply and cost-effectively while the bonding wires provide the necessary thermal barrier.
3Object-affected harmful factors
If the sensor element is suspended by bonding wires, then thermal insulation is achieved, but the assembly process becomes more complex
Solution Approach 1:
The bonding wires simultaneously provide electrical connection and thermal insulation, combining two necessary functions into a single component. This integration simplifies the assembly process compared to using separate wires for electrical connection and separate insulation structures, as the bonding wires accomplish both tasks in one assembly step.
4Stability of the object's composition
If the sensor chip thickness is increased, then thermal mass increases providing thermal stability, but the thermal time constant increases causing slower response
Solution Approach 1:
The bonding wires act as thermal intermediaries that isolate the sensor chip from the housing's thermal mass. This allows the chip to maintain its own thermal characteristics without being influenced by the housing temperature, enabling faster thermal response while maintaining stability through the insulating effect of the bonding wires.
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 design simplifies the assembly and production of the gas sensor, reduces heat transfer to other components, and provides effective insulation, resulting in cost advantages and improved thermal isolation of the sensor element.
Implementation Method 1
The bonding wires provide thermal insulation from the sensor housing
Implementation Method 2
gas-permeable but liquid-impermeable closure element
Data Source
AI summary
For a gas sensor, in particular for automobile applications, comprising a housing, which has a measurement chamber, wherein at least one sensor element having connecting wires is associated with the measurement chamber, the housing has a bottom part and a top part that covers the bottom part and each sensor element is arranged in the bottom part while suspended by the connecting wires thereof. At least one side wall of the bottom part favorably has an assembly opening, which is designed in such a way that a tool arm that retains the sensor element can be inserted into the bottom part from the outside through the assembly opening and can be brought into an assembly position in the area of the opening edge of the bottom part so that the connecting wires of the sensor element are in bondable contact with the associated connection surfaces. Thus especially easy assembly is possible.