Ceramic Heater Electrode Lead-out Member Area Variation
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Solution Overview
Problem
Ceramic heaters used in applications like glow plugs face durability issues due to high electrical resistance and contact resistance in electrode lead-out members, leading to heat generation and potential deterioration, especially under harsh conditions, and the solutions proposed in existing patents either compromise strength or increase production costs.
Innovation Solution
A ceramic heater design with electrode lead-out members featuring an area increasing section from the lead member to the electrode, which reduces electrical resistance and contact resistance, while maintaining strength and controlling volume to minimize heat generation and production costs, using a combination of area increasing, decreasing, and constant sections to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the electrode lead-out member is made thinner to ensure the strength of the ceramic heater, then the strength is improved, but the electrical resistance and contact resistance increase leading to more heat generation and deterioration
Solution Approach 1:
The electrode lead-out member features a variable cross-sectional area design where the area increases from the lead member connection toward the electrode connection. This local variation in geometry optimizes the balance between strength and electrical resistance: the thinner section near the lead member maintains overall strength, while the progressively increasing area toward the electrode reduces electrical resistance and contact resistance at the critical connection point.
2Reliability
If the area of cross section of the electrode lead-out member is made larger to decrease electrical resistance, then the electrical resistance and contact resistance are reduced, but the strength of the ceramic heater decreases
Solution Approach 1:
Instead of uniformly increasing the cross-sectional area throughout the electrode lead-out member, the invention applies local quality by varying the area along its length. The area is larger near the electrode connection where low resistance is critical, and gradually decreases toward the lead member connection where structural strength is more important, thus optimizing both electrical and mechanical properties in different locations.
3Reliability
If the volume of the electrode lead-out member is increased to reduce electrical resistance, then the electrical resistance is decreased, but the production cost increases due to more expensive noble metal usage
Solution Approach 1:
The invention changes the geometric parameter of the electrode lead-out member by implementing a variable cross-sectional area instead of a uniform area. This parameter change allows the volume of expensive noble metal to be minimized while still achieving sufficiently low electrical resistance by concentrating the material where it is most needed - near the electrode connection where contact resistance is the primary concern.
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 design enhances the durability and reliability of the ceramic heater by reducing heat generation and contact resistance, suppressing abnormal heating, and decreasing the risk of cracks, while also lowering production costs by minimizing the use of expensive noble metals.
Implementation Method 1
a heating resistor (13)... generates heat through electrical resistance when supplied with power
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The ceramic heater used in a glow plug, which is used under harsh conditions, is required to be improved in durability. The ceramic heater 11 comprising: a heating resistor 13; a first lead member 15 and a second lead member 17; a first electrode lead-out member 19 and a second electrode lead-out member 21 electrically connected, respectively, to the ends of the first and second lead member opposite to the respective ends thereof that are electrically connected to the heating resistor 13; a ceramic base23 in which the heating resistor13, the first lead member15, the second lead member17, the first electrode lead-out member19 and the second electrode lead-out member21 are embedded; and a first electrode25 and a second electrode27 that are formed on the surface of the ceramic base, wherein in the first electrode lead-out member19 the area S1 of the connection part with the first electrode is larger than the area S2 of the connection part with the first lead member.