Multi-link Engine Balancing Second-order Inertia Forces
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Solution Overview
Problem
Multi-link engines experience significant transverse vibrations due to inertia forces, leading to increased costs and decreased fuel efficiency from the need for separate balancer devices and friction-generated issues, which are not addressed in conventional piston-crankshaft structures.
Innovation Solution
A method for designing a multi-link engine that balances second-order inertia forces by configuring the mass and shape of links to distribute transverse inertia forces equally in both directions, eliminating the need for additional balancer devices and reducing friction, thereby suppressing transverse vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a separate second order balancer device is provided to reduce transverse vibrations, then vibration reduction is achieved, but device complexity and cost increase
Solution Approach 1:
The patent combines the vibration balancing function with the existing links by configuring their mass distribution and geometry. The first link and second link are designed with specific mass ratios and center of gravity positions to inherently balance second-order transverse vibrations, eliminating the need for a separate balancer device while achieving the same vibration reduction effect
Solution Approach 2:
The patent changes the physical parameters of the links, specifically the mass distribution and center of gravity positions. By setting the center of gravity of the first link at a specific position and configuring the mass ratio between the first and second links, the system achieves vibration balancing through parameter optimization rather than adding separate balancing components
2Object-affected harmful factors
If a second order balancer device is added to reduce vibrations, then transverse vibrations are reduced, but fuel efficiency deteriorates due to friction
Solution Approach 1:
The patent merges the vibration balancing function into the existing link structure, eliminating separate balancer devices that would generate friction and consume energy. The links themselves are configured with specific mass distributions to achieve vibration reduction without additional moving parts that would cause energy loss
Solution Approach 2:
The patent extracts and eliminates the separate second-order balancer device from the engine system, retaining only the essential links with optimized mass distribution. This removal of unnecessary components eliminates the friction and energy consumption associated with driving separate balancer mechanisms
3Object-affected harmful factors
If link mass and shape are configured to balance second-order inertia forces, then transverse vibrations are reduced, but manufacturing complexity increases
Solution Approach 1:
The patent specifies particular parameter ranges for link mass and geometry that achieve vibration balancing. By setting the center of gravity of the first link at a specific position and defining the mass ratio between links within certain ranges, the solution provides clear manufacturing targets that balance vibration reduction with manufacturability
Solution Approach 2:
The patent employs asymmetric mass distribution in the links, where the center of gravity of the first link is positioned at a specific location that is not at the geometric center. This asymmetric configuration is necessary to achieve the second-order vibration balancing effect while remaining manufacturable through conventional casting or forging processes
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3C
AI summary
A multi-link engine (100) is provided with an upper link (13), a lower link (14) and a control link (15). The upper link (13) is pivotally connected to a piston (11) by a piston pin (16). The lower link (14) is rotatably mounted on a crankpin (12A) of a crankshaft (12) and connected to the upper link (13) by an upper pin (17). The control link (15) is rotatably connected to the lower link (14) by a control pin (18) and pivotally mounted on a pivot portion (21) of a control shaft (20). The links (13, 14, 15) are configured and arranged with respect to each other such that inertia forces of a prescribed second or higher order in terms of an engine rotational speed act on at least the upper link (13) and the control link (15) in a transverse direction of the engine (100) with a sum of leftward and rightward inertia forces of the prescribed second or higher order being substantially zero.