Crankshaft Load Control During Engine Misfire
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Solution Overview
Problem
Existing engine load control systems during misfire fail to optimize engine output, leading to unnecessary low-load operation and decreased efficiency, as they do not effectively manage torsional vibration-induced stress on the crankshaft, which varies with misfire in multiple cylinders.
Innovation Solution
A method and system that calculate additional stress on the crankshaft based on torsional vibration evaluation, determining an output limit rate to control engine operation, ensuring the stress remains within allowable limits, thereby preventing excessive reduction in engine output during misfire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional load control systems reduce engine output to 50% when misfire occurs in two cylinders, then stable engine operation is maintained, but unnecessary low-load operation occurs and fuel efficiency decreases
Solution Approach 1:
The system dynamically changes the load control parameter (output limitation rate) based on the specific misfire condition. Instead of using a fixed 50% output limitation for two-cylinder misfire, the system calculates an appropriate output limitation rate (e.g., 95%, 80%, 70%) based on the actual additional stress on the crankshaft, allowing the engine to operate at higher loads when safe and improving fuel efficiency while maintaining reliability when necessary
Solution Approach 2:
The system implements feedback by continuously monitoring misfire detection results, calculating additional crankshaft stress based on torsional vibration evaluation, and adjusting the output limitation rate accordingly. This closed-loop control allows the system to respond to actual engine conditions rather than following fixed rules, optimizing both reliability and fuel efficiency
2Strength
If engine output is reduced to maintain stable operation during misfire, then crankshaft stress is reduced, but engine productivity and power output decrease
Solution Approach 1:
The system transitions from static load control (fixed output limitations) to dynamic load control where the output limitation rate is continuously adjusted based on real-time misfire detection and crankshaft stress calculation. This allows the engine to maintain higher power output when conditions permit while ensuring crankshaft stress remains within safe limits
Solution Approach 2:
The system changes the operational parameter (output limitation rate) based on calculated additional stress levels. When additional stress is low, the output limitation rate is reduced (allowing higher power output); when additional stress is high, the output limitation rate is increased (maintaining lower power output to protect the crankshaft)
3Device complexity
If fixed output limitation is applied during misfire, then simple control logic is maintained, but optimization of engine operation output is lost
Solution Approach 1:
The system performs self-service by automatically calculating additional crankshaft stress based on misfire detection results and torsional vibration evaluation, then autonomously determining the appropriate output limitation rate without requiring complex external control logic or manual intervention. The control unit itself generates the optimized control parameters
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 stable engine operation with improved fuel efficiency by avoiding unnecessary low-load conditions and maintaining optimal output, thus enhancing the overall efficiency of the engine power generation plant.
Implementation Method 1
misfire takes place in a cylinder or a plurality of cylinders, an engine output is lowered to an output at which stable operation is possible simultaneously with detection of misfire by a misfire-detection unit
Implementation Method 2
When misfire occurs in one or two cylinders, the torsional response amplitude of a crank shaft of an engine changes, and the aspect of the change in the torsional response amplitude is varied between the misfiring cylinders
Data Source
Figure 1~2
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AI summary
An object is to provide a method and a system of controlling a load during misfire of an engine, whereby additional stress on a crank shaft is calculated from torsional vibration of the crank shaft to obtain an output limit rate, and an operation output of an engine is controlled on the basis of the output limit rate. The method includes: a first step of calculating additional stress on a crank shaft on the basis of a vector sum of crank-shaft torsional vibration vibratory force when the misfire is detected; a second step of determining whether the calculated additional stress on the crank shaft is less than an allowable stress with respect to the crank shaft; a third step of controlling an operation output of the engine to be reduced by a predetermined amount and returning to the first step if the calculated additional stress is greater than the allowable stress and obtaining an output limit rate by calculating the additional stress on the crank shaft if it is determined that the calculated additional stress on the crank shaft is less than the allowable stress with respect to the crank shaft; and a fourth step of controlling the operation output of the engine on the basis of the output limit rate.