Fuel Injection Control Device Misfire Prevention Mode
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Solution Overview
Problem
Unstable combustion occurs when a work machine's engine is restarted after a pause, leading to rotation fluctuations and decreased workability due to low cooling water temperature, which persists until the engine is warmed up.
Innovation Solution
A fuel injection control device with a misfire avoiding mode that continues multi-stage injection when the cooling water temperature is above a certain threshold, deactivating this mode once the exhaust temperature reaches a set point and using timers and atmospheric pressure corrections to manage injection timing effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the engine is restarted after a pause and rotation speed is increased to operational speed, then the engine should quickly resume work, but unstable combustion occurs due to low cooling water temperature causing rotation fluctuations and reduced workability
Solution Approach 1:
The control device predicts the cooling water temperature at a predetermined time after engine restart based on the current cooling water temperature. This preliminary temperature prediction allows the system to prepare appropriate injection control strategies in advance, preventing unstable combustion before it occurs by maintaining multi-stage injection when temperature is predicted to be low, thus ensuring both quick work resumption and combustion stability
Solution Approach 2:
The control device continuously monitors the actual cooling water temperature and compares it with the predicted temperature. Based on this feedback, the system dynamically adjusts the fuel injection control strategy - maintaining multi-stage injection when temperature is low and switching to normal injection when temperature is sufficient. This feedback mechanism ensures combustion stability adapts to real-time temperature conditions while enabling quick operational resumption
2Reliability
If multi-stage injection is continued after engine restart to prevent unstable combustion, then combustion stability improves, but fuel consumption increases and injection system complexity rises
Solution Approach 1:
The control device predicts cooling water temperature at a future time point based on current temperature readings. This preliminary prediction enables the system to transition from multi-stage injection to normal injection at the optimal moment - just when temperature becomes sufficient - thereby preventing both unstable combustion and unnecessary prolonged multi-stage injection that would waste fuel
Solution Approach 2:
The system dynamically changes the injection control parameter (injection stage) based on the predicted cooling water temperature. When predicted temperature is below a threshold, multi-stage injection is maintained for stability; when predicted temperature exceeds the threshold, normal injection is restored to reduce fuel consumption. This parameter adaptation resolves the contradiction between combustion stability and fuel efficiency
Data Source
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AI summary
In order to eliminate noise generated by misfiring when the rotational frequency rises to the operating rotational frequency immediately after a low-temperature startup, or when the rotational frequency rises to the operating rotational frequency from an idling rotational frequency in a low-temperature state, a fuel injection control device for an internal combustion engine is equipped with: a fuel injection device that is capable of multi-stage injection of fuel (accumulated in a common rail (6)) by means of injectors (2); a cooling water temperature sensor (26) serving as a water temperature detection means that detects the temperature of cooling water in the engine (1); an exhaust temperature sensor (24) serving as an exhaust temperature detection means that detects the exhaust temperature of the engine (1); and an engine control unit (13) serving as a control device. When the engine starts up and the cooling water temperature is equal to or greater than a prescribed water temperature (T) degrees, the control device executes a misfire prevention mode whereby a multi-stage injection is continued.