Spark-Ignition Engine Starting Device Pre-Ignition Control
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Solution Overview
Problem
Spark-ignition multi-cylinder engines face challenges in preventing pre-ignition during engine restarts, especially at high temperatures, which can lead to decreased starting performance and increased vibration, due to the combination of high in-cylinder temperatures and effective compression ratios.
Innovation Solution
A starting device that includes a fuel injection timing retard-setting for cylinders on intake and compression strokes during engine restarts, along with an intake valve phase mechanism that adjusts the close timing to maintain a high effective compression ratio, and a starter motor assist for prompt engine starting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fuel injection is performed during compression stroke to improve starting torque, then engine starting performance is improved, but pre-ignition occurs due to high in-cylinder temperature
Solution Approach 1:
The fuel injection is performed in advance during the expansion stroke rather than during the compression stroke. This preliminary timing ensures that the fuel is injected when the in-cylinder temperature is lower, preventing pre-ignition while still achieving effective combustion to produce starting torque
Solution Approach 2:
The injection timing parameter is changed from compression stroke to expansion stroke. This parameter change adapts the fuel injection strategy to the high-temperature conditions during engine restart, avoiding pre-ignition by injecting fuel when temperatures are more favorable
2Object-affected harmful factors
If fuel injection timing is retarded to avoid pre-ignition, then pre-ignition is prevented, but starting torque decreases
Solution Approach 1:
Fuel injection is performed preliminarily during the expansion stroke before the compression stroke begins. This timing allows the fuel to be introduced when temperatures are lower, preventing pre-ignition while ensuring sufficient time for vaporization and combustion to generate adequate starting torque
Solution Approach 2:
The fuel injection and combustion process is designed to continue effectively from the expansion stroke through the compression stroke. By injecting fuel during expansion and maintaining combustion through compression, the system ensures continuous useful action that produces starting torque without causing pre-ignition
3Productivity
If intake valve close timing is advanced to increase effective compression ratio for cold start, then cold start performance is improved, but pre-ignition risk increases at high engine temperature
Solution Approach 1:
The intake valve close timing is made dynamic rather than fixed. The valve phase variable mechanism adjusts the close timing based on engine temperature conditions, advancing the timing for cold starts to improve compression ratio and retarding it for hot restarts to prevent pre-ignition
Solution Approach 2:
The intake valve close timing parameter is changed based on engine temperature. During hot restarts, the timing is retarded to reduce the effective compression ratio and prevent pre-ignition, while during cold starts, the timing is advanced to increase the effective compression ratio for better starting performance
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 solution effectively prevents pre-ignition by injecting fuel early in the expansion stroke and retarding ignition timing, maintaining high starting torque and ensuring a prompt engine start while avoiding the need to reduce the effective compression ratio.
Implementation Method 1
a fuel injection valve (53) for injecting fuel into the respective cylinders (11)
Implementation Method 2
ignition plugs (51) for igniting mixture gas inside the respective cylinders (11)
Implementation Method 3
an engine-driven hydraulic pressure supply source (81) for supplying a predetermined hydraulic pressure to the variable valve phase mechanism (32)
Implementation Method 4
a variable valve phase mechanism (32) for changing a close timing of each of the intake valves (21) between a predetermined most advanced timing and a predetermined most retarded timing
Data Source
AI summary
A starting device of a spark-ignition multi-cylinder engine is provided. The device includes a multi-cylinder engine body having cylinders, fuel injection valves, ignition plugs, an intake valve drive mechanism for opening and closing intake valves, a hydraulic variable valve phase mechanism for changing a close timing of each intake valve, an engine-driven hydraulic pressure supply source for supplying a hydraulic pressure, and a start controller for controlling the fuel injection valves, the ignition plugs, and the variable valve phase mechanism. When the supplied hydraulic pressure is below a predetermined pressure, the variable valve phase mechanism locks the close timing. When an engine temperature in an engine-start is high, the start controller retards a fuel injection timing of the cylinder on intake stroke at an engine stopped timing and retards an ignition timing thereof. The start controller does not retard the close timing of the intake valve until the engine-start completes.