Ceramic Substrate Resistance for Glow Plug Temperature Estimation
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Solution Overview
Problem
Existing methods for estimating the surface temperature of heaters, such as glow plugs, are inaccurate due to variations in coolant temperature, engine oil temperature, and production-related factors, affecting the reliability of temperature estimation and control.
Innovation Solution
A temperature estimation apparatus and method that utilizes the ceramic substrate's varying electrical resistance, focusing on the highest temperature portion between the conductor and heating element to dominate the substrate resistance, thereby mitigating external and production-related influences, allowing for accurate temperature estimation and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electrical resistance of the heating element is used to estimate the surface temperature of the glow plug, then the temperature estimation can be performed, but the accuracy is poor due to variations in coolant temperature, engine oil temperature, and production-related factors
Solution Approach 1:
The patent extracts the temperature sensing function from the heating element itself by utilizing the ceramic substrate's electrical resistance properties. Instead of relying on the heating element's resistance which is affected by multiple external factors, the invention measures the resistance of the ceramic substrate between the heating element and the external electrode, isolating the temperature measurement from harmful environmental influences.
Solution Approach 2:
The ceramic substrate acts as an intermediary between the heating element and the external environment. By measuring the electrical resistance through the substrate rather than directly through the heating element, the system obtains temperature information while filtering out the effects of coolant temperature, oil temperature, and production variations.
2Measurement precision
If complex corrections are applied to account for coolant temperature, engine oil temperature, and production variations, then the temperature estimation accuracy may improve, but the device complexity and measurement process become more complicated
Solution Approach 1:
The patent removes the need for complex correction systems by extracting the temperature sensing function to the ceramic substrate itself. The substrate's electrical resistance naturally provides temperature information without requiring separate sensors or complex computational corrections for environmental factors.
Solution Approach 2:
The ceramic substrate serves itself as both the structural component and the temperature sensing element. The substrate's inherent electrical resistance property provides temperature information directly, eliminating the need for external correction mechanisms or additional sensing components.
3Ease of operation
If the electrical resistance of the heating element is used for temperature estimation, then the measurement can be obtained, but the measurement is strongly influenced by production-related variations and external environment
Solution Approach 1:
The patent extracts the measurement function from the heating element to the ceramic substrate. By measuring resistance between the external electrode and the heating element through the substrate, the system obtains temperature information that is not affected by production variations in the heating element or external environmental conditions.
Solution Approach 2:
The ceramic substrate mediates between the heating element and the measurement circuitry. This intermediary role allows the system to obtain temperature information while blocking the transmission of production-related variations and environmental influences to the measurement.
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 accuracy of temperature estimation and control by using the substrate resistance as a dominant factor, reducing the impact of external and production-related variations, and simplifies the measurement process, eliminating the need for complex corrections.
Implementation Method 1
the electrical resistance of the substrate strongly varies with the temperature, and a portion of the substrate having a higher temperature has a smaller electrical resistance
Implementation Method 2
A glow plug is widely used as an auxiliary heat source of a compression-ignition-type internal combustion engine
Data Source
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AI summary
[Objective] An object is to improve the accuracy in estimating the temperature of a heater or to accurately control the temperature of the heater. [Means for Solution] A heating apparatus includes a heater and an energization section. The heater includes a conductor, a heating element which generates heat when electricity is supplied thereto, and a substrate. The substrate is formed of ceramic, and the conductor and the heating element are separately embedded and held in the substrate. The energization section supplies electricity to the heating element as to cause the heater to generate heat. The heating apparatus further includes an obtainment section which obtains the electrical resistance of the substrate between the conductor and the heating element. It is possible to accurately estimate the temperature of the substrate or accurately control the temperature of the substrate on the basis of the electrical resistance obtained by the obtainment section.