Rounded Sensor Contact Surface for Assembly Tolerance
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Solution Overview
Problem
Existing sensor elements face challenges in reducing contact surface area to minimize precious metal usage while ensuring reliable electrical contact, particularly due to manufacturing tolerances and assembly errors, which can lead to inconsistent connections and increased assembly errors.
Innovation Solution
The contact surfaces are rounded to reduce their area and length, with a specific radius of curvature, allowing for a significant reduction in contact surface area to 2% or less of the sensor element's largest area, and ensuring reliable electrical connections through a combination of mechanical and electrical design features such as oval trunk areas and circular head areas, minimizing material usage and assembly errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the contact surface area is reduced to minimize precious metal usage, then material cost is reduced, but assembly reliability deteriorates due to manufacturing tolerances and alignment errors
Solution Approach 1:
The contact surface is designed with a rounded contour instead of sharp corners, creating a curved geometry that provides tolerance compensation. This curvature allows the contact surface to maintain reliable electrical connection even when manufacturing tolerances or assembly misalignments occur, as the rounded shape can accommodate positional variations without losing contact.
Solution Approach 2:
The invention changes the geometric parameters of the contact surface by introducing a minimum radius of curvature (R ≥ 0.3 mm). This parameter modification transforms the contact surface from a conventional rectangular shape to a rounded shape, enabling reduced material usage while maintaining assembly reliability through the curvature-induced tolerance compensation.
2Ease of manufacture
If the contact surface area is reduced, then production cost is reduced, but the frequency of assembly errors increases
Solution Approach 1:
The rounded contour with minimum radius of curvature R ≥ 0.3 mm provides a geometric feature that is more tolerant to manufacturing variations. This curvature ensures that even with reduced dimensions and lower production costs, the contact surface maintains reliable connection by accommodating assembly misalignments that would otherwise cause errors with smaller, sharper contact surfaces.
Solution Approach 2:
The rounded geometry of the contact surface acts as a pre-designed cushion against assembly errors. By incorporating this curvature in advance, the design compensates for potential manufacturing tolerances and alignment variations before assembly occurs, preventing assembly errors rather than correcting them afterward.
3Quantity of substance
If the contact surface dimensions are reduced, then material usage is minimized, but the risk of shunt resistance increases
Solution Approach 1:
The rounded contour with minimum radius of curvature R ≥ 0.3 mm reduces the overall contact surface area and material usage while simultaneously mitigating the risk of shunt resistance. The curvature distributes electrical current more evenly across the contact interface and eliminates sharp corners that could concentrate stress or create unintended current paths, thereby reducing shunt resistance risk despite reduced material quantity.
Data Source
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AI summary
The invention relates to a sensor element, in particular for detecting a physical property of a gas, in particular for detecting the concentration of a gas component or the temperature or a solid constituent or a liquid constituent of an exhaust gas of an internal combustion engine. The sensor element (20) has, for example, a solid electrolyte film (21) and has a first end region and a second end region (202) opposite each other in a longitudinal direction of the sensor element. The sensor element (20) has a functional element outside of the second end region (202), in particular in the first end region, which functional element is connected in an electrically conductive manner to a contact surface (43, 44) arranged on the outer surface of the sensor element (20) in the second end region (202). The sensor element is characterized in that the contact surface (43) is rounded, for example with a radius (R), on the side of the contact surface facing away from the first end region (201). The contact surfaces (43, 44) comprise, in particular, three partial regions: head region (432, 442), neck region (433, 443), and torso region (431, 441).