Rack-Driven Eccentric Sleeve for Variable Compression Engines
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Solution Overview
Problem
Existing internal combustion engines face challenges in efficiently adjusting compression ratios without increasing space, causing vibration, noise, and burdening the crank pin and crankshaft, especially when changing environments require adaptive compression settings.
Innovation Solution
A variable compression ratio engine design incorporating a gear eccentric sleeve with a rack and block system allows for easy adjustment of the eccentric sleeve's posture, enabling simple and efficient changes in compression ratio by engaging the rack with the gear eccentric sleeve, reducing vibration and noise, and minimizing the load on the crank pin and crankshaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a hydraulic device is used to rotate the eccentric sleeve, then the compression ratio can be adjusted, but the piping angle control and system complexity increase
Solution Approach 1:
The patent replaces the hydraulic device with a purely mechanical rack-and-pinion gear system. The rack, when moved linearly, engages with the pinion gear on the eccentric sleeve to rotate it mechanically, eliminating the need for hydraulic piping and control systems while achieving the same compression ratio adjustment function.
Solution Approach 2:
The rack-and-pinion gear acts as an intermediary mechanism between the linear motion of the rack and the rotational motion of the eccentric sleeve. This intermediary mechanical transmission simplifies the control system by converting simple linear displacement into precise rotational adjustment without requiring complex hydraulic control.
2Adaptability or versatility
If rods and mechanical devices are connected to the eccentric sleeve, then the compression ratio can be changed, but fast reciprocating motion, strong shock, vibration, noise, increased load, and increased space are generated
Solution Approach 1:
The patent merges the rack and pinion gear into an integrated compact unit where the pinion is directly mounted on the eccentric sleeve. This consolidation reduces the number of separate mechanical components and connection points, thereby minimizing vibration sources and noise generation while maintaining the compression ratio adjustment function.
Solution Approach 2:
The mechanism is segmented into distinct functional components (rack, pinion gear, eccentric sleeve) that are independently optimized. The rack provides linear motion, the pinion converts it to rotation, and the eccentric sleeve adjusts the compression ratio, allowing each component to be designed for minimal vibration and noise in its specific function.
3Adaptability or versatility
If the length of the connecting rod is changed, then the compression ratio can be adjusted, but the crank pin and crankshaft bear increased burden
Solution Approach 1:
The patent introduces a dynamic adjustment mechanism where the eccentric sleeve can be rotated to change the effective compression ratio during engine operation. This allows the engine to adapt compression ratios dynamically based on operating conditions without permanently altering the connecting rod length or increasing mechanical loads on the crankshaft.
Solution Approach 2:
The invention changes the geometric parameter of the eccentric sleeve's rotation angle to adjust the compression ratio. By varying this angular parameter rather than changing the physical length of the connecting rod, the system achieves compression ratio adjustment without increasing the mechanical burden on the crank pin and crankshaft.
4Adaptability or versatility
If a five-bar linkage is used instead of one connecting rod, then the compression ratio can be changed, but the device complexity increases
Solution Approach 1:
The eccentric sleeve with rack-and-pinion mechanism serves multiple functions: it maintains the primary connecting rod function while simultaneously providing compression ratio adjustment capability. This multi-functional design avoids the need for a separate five-bar linkage system, keeping the structure simple while achieving variable compression ratio.
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 design allows for cost-effective, efficient, and performance-enhanced engine operation with reduced fuel consumption and pollutant emissions by allowing for adaptive compression ratio adjustments without increasing engine complexity or space requirements.
Implementation Method 1
at least one rack engaged with a gear formed on an outer circumferential surface of the gear eccentric sleeve
Data Source
AI summary
A variable compression ratio engine is provided, which includes a connecting rod including a small end connected to a piston through a piston pin, and a big end connected to a crankshaft through a crank pin, a gear eccentric sleeve installed on at least one of the piston pin and the crank pin, and at least one rack engaged with a gear formed on an outer circumferential surface of the gear eccentric sleeve at one side thereof.