Variable Compression Ratio Engine Lever Mechanism
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Solution Overview
Problem
Existing variable compression ratio mechanisms in internal combustion engines face challenges in optimizing the relationship between engine compression ratio and speed reduction ratio, leading to suboptimal retention and responsiveness, particularly under varying load conditions.
Innovation Solution
A variable compression ratio mechanism that adjusts the rotation angle of a first control shaft, coupled with a connecting mechanism including a second control shaft and a lever, optimizes the speed reduction ratio and load distribution across different compression ratios, ensuring maximum retention and responsiveness by setting the speed reduction ratio and load accordingly based on the compression ratio setting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the speed reduction ratio is increased at a given compression ratio setting, then the rotation angle retention is improved, but the responsiveness of compression ratio change deteriorates
Solution Approach 1:
The patent applies dynamics by making the speed reduction ratio variable rather than fixed. The connecting mechanism dynamically adjusts the speed reduction ratio based on the compression ratio setting: at low compression ratio settings, a higher speed reduction ratio is provided to improve retention, while at high compression ratio settings, a lower speed reduction ratio is provided to enhance responsiveness. This dynamic adaptation resolves the contradiction between retention and responsiveness.
2Object-affected harmful factors
If the actuator is placed outside the engine body to protect against oil and exhaust heat, then the actuator is protected from harmful factors, but the device complexity increases due to the coupling mechanism
Solution Approach 1:
The patent uses an intermediary approach by placing the actuator outside the engine body in a protected location, and introducing a coupling mechanism (including the connecting mechanism with first and second control shafts and lever) as an intermediary to transmit rotational force from the actuator to the compression ratio control system. This intermediary arrangement protects the actuator from harmful factors while maintaining functional connectivity.
3Speed
If the speed reduction ratio is decreased at high compression ratio settings, then the responsiveness is improved, but the load on the lever increases
Solution Approach 1:
The patent applies parameter changes by optimizing the speed reduction ratio as a variable parameter that changes according to the compression ratio setting. At high compression ratio settings, the speed reduction ratio is decreased to improve responsiveness, and the lever arm dimensions are optimized to manage the resulting load. This parameter optimization resolves the contradiction between responsiveness and load by adjusting the speed reduction ratio and lever geometry together.
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 optimization enhances the retention of engine compression ratio and improves responsiveness by maintaining high speed reduction at low compression ratios and reducing load on the actuator, thereby achieving compactness and reduced energy consumption, while minimizing the risk of knocking during rapid acceleration.
Implementation Method 1
a lever coupling the first control shaft and the second control shaft. One end of the lever is coupled to a tip of a first arm portion extending radially outwardly from the center of the first shaft on the one hand, while the other end of the lever is coupled to a tip of a second arm portion extending radially outwardly from the center of the second shaft on the other
Data Source
AI summary
In a variable compression ratio engine with a connecting mechanism including a first control shaft to control the compression ratio of a variable compression ratio, a second control shaft to be rotated/retained by an actuator, and a lever interconnecting the first control shaft and the second control shaft, a speed reduction ratio from the actuator to the first control shaft through the rotation power transmission path is set to be maximum at the maximum compression ratio, at a preset compression ratio (i.e. at any given compression ratio between the minimum compression ratio and the maximum compression ratio) the speed reduction ratio is set to be minimum, and the reduction ratio is set higher at the maximum compression ratio as compared to the intermediate compression ratio.