Glow Plug Driving Control with Series Inductor for Current Smoothing
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Solution Overview
Problem
The high current variation during the energization of glow plugs in diesel engines leads to electrical stress, accelerated deterioration, and reduced lifespan, along with increased power dissipation and noise, which affects the reliability of the starting aid system.
Innovation Solution
A glow plug driving control apparatus that includes a current stability element inserted in series during energization start, which is then excluded from the path after a specific condition is met, smoothing the current flow and preventing large momentary currents, thereby reducing electrical stress and power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PWM voltage control is applied to the glow plug, then flexible voltage setting and small power loss are achieved, but current variation according to voltage variation becomes large, causing electrical stress and expedited deterioration
Solution Approach 1:
An inductor is introduced as an intermediary component in the glow plug driving circuit. The inductor acts as a mediator between the PWM control signal and the glow plug, smoothing the current waveform and reducing peak current variations while preserving the PWM voltage control functionality. This resolves the contradiction by allowing flexible voltage control without the harmful current spikes that reduce glow plug lifespan.
2Power
If high power dissipation is allowed in the glow plug, then effective heating for diesel engine starting is achieved, but current variation reaches several tens of amperes at peak, causing electrical stress and shortened life
Solution Approach 1:
The inductor provides beforehand cushioning by smoothing the current waveform before it reaches the glow plug. The inductive reactance opposes rapid current changes, cushioning the peak currents that would otherwise cause electrical stress. This allows the glow plug to operate at high power dissipation levels continuously without premature failure from current spikes.
3Speed
If momentary large current is permitted at energization start, then quick glow plug activation is achieved, but electrical stress is applied and deterioration is accelerated
Solution Approach 1:
The inductor serves as a mediator that permits rapid activation while protecting against damaging current spikes. By placing the inductor in series with the glow plug, the circuit achieves fast response to PWM signals while the inductor's current-smoothing effect prevents momentary large currents from causing electrical stress and deterioration.
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 extends the lifespan of the glow plug, reduces power dissipation, suppresses noise, and enhances the reliability of the apparatus by minimizing electrical stress and false operations in neighboring electronic circuits.
Implementation Method 1
a current stability element is inserted in series in an energization path of the glow plug... a current flowing to the glow plug is smoothed
Data Source
AI summary
A glow plug driving control apparatus. The glow plug driving control apparatus includes a glow switch 2 and a glow plug 1 which are connected in series between a power supply and ground, and an electrical controlling unit 101 which controls opening and closing of the glow switch 2, and that can perform energization driving of the glow plug 1. The glow plug driving apparatus also includes an energization path switching switch 5 that connects in series a stability coil 3 in a serial connection path of the glow switch 2 and the glow plug 1 at the time of an energization start of the glow plug 1, and after the energization start, causes both the glow switch 2 and the glow plug 1 to return to a serial connection state between the power supply and the ground.