Glow Plug Diagnosis via Resistance Gradient
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Solution Overview
Problem
Existing methods for diagnosing the aging and fault of glow plugs in internal combustion engines are unreliable due to interference from cooling associated with air intake/exhaust or fuel injection, which affects resistance value measurements, and can promote the aging of the glow plug.
Innovation Solution
A method that involves energizing the glow plug when the key switch is turned on, measuring its resistance value at the start and after a predetermined time, calculating the resistance value gradient, and determining the plug's condition based on predefined gradient reference values to accurately diagnose aging or fault without engine operation interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resistance value measurement is performed during engine operation, then diagnostic function is provided, but measurement accuracy deteriorates due to cooling effects from air intake/exhaust or fuel injection
Solution Approach 1:
The patent applies preliminary action by measuring the resistance value of the glow plug before engine operation begins (when the key switch is turned on but engine hasn't started). This timing ensures that cooling effects from air intake/exhaust or fuel injection have not yet occurred, thereby maintaining high measurement precision while providing reliable diagnostic information about glow plug aging or faults
2Reliability
If voltage correction is applied to compensate for glow plug aging, then operational performance is maintained, but glow plug aging is accelerated
Solution Approach 1:
The patent segments the diagnostic approach into two distinct gradient thresholds: a first gradient reference value that indicates normal aging (where no correction is needed) and a second gradient reference value that indicates faulty condition (where correction may be considered). By measuring resistance change over time and comparing against these segmented thresholds, the system avoids unnecessary voltage corrections that would accelerate aging, while still maintaining startability when genuinely needed
Solution Approach 2:
The patent changes the diagnostic parameter from simple resistance value to resistance value gradient (rate of change over time). This parameter transformation allows distinction between normal aging patterns and faulty conditions, enabling more nuanced diagnostic decisions that avoid premature or unnecessary voltage corrections, thereby extending glow plug service life while maintaining operational reliability
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 allows for a highly reliable diagnosis of glow plug aging or fault by measuring resistance value changes before engine startup or shutdown, unaffected by cooling processes, ensuring accurate and reliable results.
Implementation Method 1
a step of energizing a glow plug in a predetermined manner when a key switch of a vehicle is turned on
Implementation Method 2
cooling associated with air intake/exhaust or fuel injection may cause a change in the resistance value of the glow plug
Data Source
AI summary
Disclosed is a glow plug diagnosis method of being able to diagnose the aging or fault of a glow plug without being affected by cooling associated with air intake/exhaust or fuel injection, the method including: a step (S102) of energizing a glow plug 1 in a predetermined manner when a key switch 11 of a vehicle is turned on; and a step (S106) of measuring the resistance value of the glow plug 1 when the energization of the glow plug 1 is started, and the resistance value of the glow plug when the energization of the glow plug 1 is started and then a change in the resistance value is saturated, and of calculating a change in the resistance value over time as a resistance value gradient, in which it is determined that the glow plug 1 is normal when the resistance value gradient exceeds a predetermined first gradient reference value a, and it is determined that the glow plug 1 is faulty, and a warning lamp or the like is lighted when the resistance value gradient is less than a predetermined second gradient reference value b (S112 and S118).