Ceramic Separator Recesses for Gas Sensor Dimensional Accuracy
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Solution Overview
Problem
Existing gas sensors face challenges in achieving dimensional accuracy of ceramic separators due to frictional forces during firing, leading to dimensional differences between the upper and lower surfaces, which affect the positioning of metal terminal members and overall sensor performance.
Innovation Solution
The introduction of recess regions on the ceramic separator, which reduces the contact area with the firing bed, allowing for even shrinkage and maintaining dimensional accuracy by ensuring the recess regions occupy at least half of the total area, thereby minimizing frictional forces and ensuring uniform shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the green separator is placed on a firing bed with its lower surface in contact with the bed, then the separator can be fired to obtain the final product, but frictional force develops between the lower surface and the bed which restrains shrinkage and causes dimensional difference between upper and lower surfaces
Solution Approach 1:
The separator is divided into multiple segments along its axial direction, with each segment having independent recess regions on its lower surface. This segmentation allows different portions of the separator to have controlled contact with the firing bed, reducing overall frictional restraint during shrinkage while maintaining structural integrity of the final product
Solution Approach 2:
Recess regions are selectively formed only on the lower surface of the separator where contact with the firing bed occurs. These recess regions create localized areas of reduced contact, allowing the lower surface to shrink uniformly without being restrained by friction across the entire surface area
2Strength
If the green separator undergoes firing, then the separator obtains its final shape and strength, but the upper surface shrinks more than the lower surface due to friction, causing dimensional inaccuracy
Solution Approach 1:
Recess regions are formed on the lower surface of the green separator before the firing process begins. This preliminary action ensures that when firing occurs, the contact area between the separator and firing bed is already reduced, allowing uniform shrinkage to occur during the strength-building firing process without dimensional distortion
Solution Approach 2:
The geometry of the lower surface is changed by forming recess regions, which modifies the contact parameters between the separator and firing bed. This parameter change reduces the frictional force during firing, allowing the separator to achieve both sufficient strength development and dimensional accuracy simultaneously
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 approach enhances the dimensional accuracy of the ceramic separator, improving the positional accuracy of metal terminal members and maintaining uniformity in the separator's dimensions, thus improving the overall performance and reliability of the gas sensor.
Implementation Method 1
when the green separator 1000x of FIG. 13A is fired, a separator 1000 of FIG. 13B obtained by firing shrinks such that its upper surface has reduced dimensions
Implementation Method 2
frictional force F develops between the lower surface and the bed 120 as shown in FIG. 13B. This is a result of the tendency of the green separator 1000x to shrink, and the frictional force F restrains the shrinkage
Data Source
AI summary
A gas sensor (1) including a sensor element (10) and a separator (90) having an element hole (90h), as viewed from one of a forward-end or a rear-end side in the axial direction. The separator has end surfaces (90e) located axially farthest toward the one of the forward-end or the rear-end side, recess regions (90h), (90r 1) and (90r 2) recessed from the end surfaces, and regions R1 and R2. First regions R1 are determined by eliminating a region SB occupied by the sensor element from a region SA defined by imaginary short-side lines and the outer edge of the separator. Second regions R2 are determined by eliminating the region SB from a region SC defined by imaginary long-side lines and the outer edge of the separator. S2/S1≥0.5 is satisfied, where S1 is the total area of R1 and R2, and S2 is the total area of the recess regions.