Ceramic heater and liquid heating device
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Solution Overview
Problem
The challenge is to downsize a ceramic heater while maintaining its heat generation capabilities and preventing a decrease in lifespan due to increased temperature and potential cracking.
Innovation Solution
A ceramic heater design with a heat generation portion that has a length-to-diameter ratio of 8 or greater, embedded in a ceramic sheet around a ceramic base, with a maximum outer diameter of 1.5 to 5.0 mm and an electric resistance value of at least 12Ω at 180°C, ensuring effective heat transfer and suppressing excessive temperature increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the ceramic heater is downsized to reduce device size, then the device can be compacted, but the heat generation area becomes small requiring higher heater temperature which decreases heater life due to cracking
Solution Approach 1:
The invention changes the geometric parameters of the heater by establishing a specific relationship between heat generation portion length (Lh) and outer diameter (D) where Lh/D ≥ 8. This parameter optimization allows the heater to maintain adequate heat generation area while achieving downsizing, thereby preventing excessive temperature increases and extending heater life
Solution Approach 2:
The invention emphasizes the axial-line direction dimension (length Lh) relative to the radial dimension (diameter D) by requiring Lh/D ≥ 8. This dimensional approach increases the heat generation area along the axial direction, improving heat transfer efficiency to the liquid and reducing the need for excessive temperature increases that would compromise heater life
2Volume of moving object
If the heat generation area is reduced to downsize the heater, then the heater becomes more compact, but the heater temperature must be increased to generate the same heat which causes cracking and reduces life
Solution Approach 1:
The invention optimizes the geometric parameters by setting Lh/D ≥ 8, which maintains an adequate heat generation area relative to the heater size. This prevents the need to excessively increase heater temperature while achieving downsizing, thus avoiding thermal stress-induced cracking
Solution Approach 2:
By prioritizing the axial length dimension (Lh) over the radial dimension (D) with the ratio Lh/D ≥ 8, the invention maintains sufficient heat generation surface area for effective liquid heating, reducing the requirement for high operating temperatures that would cause cracking
3Productivity
If the heat generation area is increased to maintain heat output, then heat transfer efficiency improves, but the heater size increases which contradicts downsizing requirements
Solution Approach 1:
The invention achieves optimal heat transfer efficiency by setting the parameter relationship Lh/D ≥ 8. This geometric optimization ensures adequate heat generation area for effective liquid heating while maintaining a compact overall heater size, thus improving productivity without increasing volume
Solution Approach 2:
The invention maximizes heat transfer efficiency by extending the heat generation portion along the axial-line direction (increasing Lh) rather than increasing the radial diameter (D). This dimensional approach maintains a compact cross-sectional profile while providing sufficient heat generation surface area for efficient liquid heating
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 allows for the downsizing of ceramic heaters while maintaining heat transfer efficiency and preventing lifespan reduction due to cracking, ensuring effective heating of liquids like water.
Implementation Method 1
a heat generation portion (17a), both ends of which are connected to lead portions (17b, 17b), and the heat generation portion has a length Lh in an axial-line L direction
Implementation Method 2
heat of the heat generation portion can be effectively transferred to the liquid
Data Source
AI summary
A ceramic heater 171,172 comprising: a ceramic base 17g extending in an axial-line-L direction; and a heat generation portion 17a, wherein a length Lh in the axial-line direction of the heat generation portion and a maximum outer diameter D of the ceramic heater satisfy a relationship of 8≤Lh/D.