Odd-Cylinder Engine Partial Cutoff for Efficiency
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Solution Overview
Problem
Spark-ignition engines face inefficiencies in partial load operation due to throttle control, leading to increased charge cycle losses and unpleasant engine noise in multi-cylinder engines with an odd number of cylinders, as conventional solutions require substantial modifications and result in irregular firing patterns.
Innovation Solution
A method for operating a multi-cylinder internal combustion engine with an odd number of cylinders arranged in line, where each cylinder is fired and cut off intermittently at a specific interval during partial load operation, maintaining a regular firing pattern and reducing throttle-related losses without modifying the engine structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If throttle control is used to adjust load in spark-ignition engines, then power output can be controlled, but charge cycle losses increase and engine efficiency decreases
Solution Approach 1:
The engine is divided into multiple cylinders, and during partial load operation, only a subset of cylinders is activated while others are cut off. This segmentation allows the engine to reduce charge cycle losses by limiting the number of cylinders undergoing the full throttle-controlled charge cycle, thereby improving overall efficiency without sacrificing power control capability.
2Loss of energy
If conventional cylinder cutoff is applied in multi-cylinder engines with odd number of cylinders, then efficiency improves, but irregular firing patterns occur causing unpleasant engine noise
Solution Approach 1:
The patent implements a periodic action by systematically rotating which cylinders are cut off and which are active across different operating cycles. This periodic rotation ensures that all cylinders share the cutoff duty equally over time, maintaining a regular and harmonious firing pattern that reduces engine noise while still achieving efficiency improvements through partial cylinder cutoff during partial load operation.
3Loss of energy
If direct injection or variable valve gear is used to dethrottle the engine, then efficiency improves, but substantial modifications to the engine structure are required
Solution Approach 1:
The patent employs a control strategy that replicates the beneficial effects of complex dethrottling systems (direct injection or variable valve gear) through a simpler cylinder cutoff approach. By carefully controlling which cylinders are active and implementing periodic rotation of cutoff patterns, the system achieves similar efficiency improvements without requiring physical modifications to the engine structure, injection systems, or valve mechanisms.
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 achieves dethrottling and improves engine efficiency by maintaining a harmonious engine noise and reducing charge cycle losses, making it suitable for retrofitting existing engines without the drawbacks of irregular firing patterns.
Implementation Method 1
Spark-ignition engines operate with a homogeneous fuel-air mixture
Data Source
AI summary
A method for partial cylinder cutoff is provided. The method comprises operating a multi-cylinder internal combustion engine with applied ignition, in which an odd number n of cylinders is arranged in line, and during partial-load operation when engine load is below threshold, enabling a partial cutoff of the cylinders, the partial cutoff comprising operating each cylinder only intermittently such that each cylinder is fired and cut off in turn at an interval of (2*720° CA)/n.