Variable Compression Ratio Crank Arm Guide Surfaces
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Solution Overview
Problem
Existing variable compression ratio apparatuses face issues with durability due to direct transmission of combustion pressure to links, leading to complex structures and reliability concerns, particularly in confining the movement trajectory of eccentric links without additional devices.
Innovation Solution
A variable compression ratio apparatus featuring a crankshaft, connecting rod, eccentric links, and a control device with guide surfaces on the crank arm to stabilize the movement of eccentric links, eliminating the need for separate devices to confine their trajectory, thereby simplifying the structure and enhancing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a separate apparatus is included to confine the movement trajectory of the link, then the movement trajectory is confined, but the structure becomes complicated
Solution Approach 1:
The guide surfaces are integrated directly into the crank arm structure, merging the trajectory confinement function with the existing crank mechanism. This eliminates the need for separate confinement apparatus while maintaining effective control over the link's movement trajectory, thereby reducing structural complexity while preserving stability.
Solution Approach 2:
The crank arm is designed to serve multiple functions: it not only transmits rotational motion but also incorporates guide surfaces that confine the movement trajectory of the eccentric link. This multi-functional design eliminates the need for dedicated confinement devices, simplifying the overall structure while maintaining operational stability.
2Power
If combustion pressure is directly transmitted to the links, then the force transmission is direct, but the durability of the links deteriorates
Solution Approach 1:
The connecting rod acts as an intermediary between the piston and the crankshaft, mediating the transmission of combustion pressure. The guide surfaces on the crank arm further mediate the interaction with the eccentric link, distributing forces more evenly and reducing direct stress concentration on the links, thereby improving durability while maintaining effective power transmission.
3Ease of operation
If the links are horizontally widened or separated when the piston descends, then the movement freedom is increased, but the operation reliability decreases
Solution Approach 1:
The eccentric link structure inherently guides its own movement through the guide surfaces on the crank arm. The geometry of the link and the guide surfaces work together to automatically maintain proper alignment and confinement during piston descent, eliminating the need for additional external confinement devices while ensuring reliable operation.
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
The solution effectively confines the movement trajectory of eccentric links without additional devices, improving operation stability and reducing manufacturing costs while maintaining the ability to adjust compression ratios according to engine load conditions.
Implementation Method 1
guide surfaces formed in a predetermined thickness at an inner circumferential surface of the crank arm so that the first and second branches of the swing link slide to move between the guide surfaces
Data Source
AI summary
A variable compression ratio apparatus may include a crankshaft, a connecting rod, first and second eccentric links mounted at both sides of the connection rod, respectively, and having one ends at which the piston pin may be eccentrically and rotatably installed, a swing link of which one end may be branched into two parts to form first and second branches, the first and second branches being connected to the other ends of the first and second eccentric links, and a control device connected to the other end of the swing link to control the swing link, wherein the crank arm includes guide surfaces formed in a predetermined thickness at an inner circumferential surface of the crank arm so that the first and second branches of the swing link slide to move between the guide surfaces.