Crankshaft Counterweight Layout for Balancing Asymmetric Engines
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Solution Overview
Problem
Internal combustion engines with non-symmetric crankshafts face challenges in balancing free inertia forces and moments, leading to engine vibrations and increased main bearing loads, which existing technologies struggle to address effectively.
Innovation Solution
The use of a combination of separately formed and integrally formed counterweights on the crankshaft, where at least one counterweight is formed as a separate element and another as an integral part of the crankshaft, allowing for varied masses and angular positions to optimize balancing properties while reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If counterweights are formed as separate elements and connected to the crankshaft, then the freedom in choosing counterweight masses is increased, but the device complexity increases due to additional coupling elements
Solution Approach 1:
The counterweight system is segmented into multiple independent counterweights that can be individually selected and arranged on the crankshaft. Each counterweight can have different mass values and angular positions, allowing flexible customization of the balancing system without requiring a completely integrated design.
Solution Approach 2:
The crankshaft is designed with multiple standardized mounting positions for counterweights, where each position can accommodate counterweights of various masses. This universal mounting system allows the same crankshaft structure to be adapted for different balancing requirements by simply changing the counterweight configuration.
2Reliability
If multiple types of counterweights with different masses are used, then the balancing properties are improved, but the manufacturing costs increase
Solution Approach 1:
Instead of using completely different counterweight designs, the system varies the mass parameter of counterweights while maintaining a standardized form factor and mounting interface. This allows different masses to be achieved through material removal or addition to a base design, simplifying manufacturing compared to creating entirely different components.
Solution Approach 2:
The counterweights are designed with standardized geometries and mounting features, where only the mass-determining dimensions vary. This local differentiation allows most of the counterweight structure to be manufactured using the same processes, while only specific regions are modified to achieve the required mass variations.
3Reliability
If counterweights are arranged at non-zero angles with respect to opposite crank pin positions, then the balancing effectiveness is improved, but the device complexity increases
Solution Approach 1:
The counterweights are deliberately positioned at asymmetric angular locations relative to the crank pin, rather than symmetrically opposite positions. This asymmetric arrangement creates more effective balancing moments by distributing the counterbalancing mass in optimized angular positions that better compensate for the inertial forces generated by the crank mechanism.
Data Source
AI summary
The present invention provides an internal combustion engine comprising a crankshaft, the crankshaft comprising main bearing journals and cranks for connecting the crankshaft to piston rods of the engine, wherein the crankshaft is provided with counterweights, wherein at least a first counterweight is formed as a separate element and connected to the crankshaft. The present invention is characterized in that at least a second counterweight is formed integrally with the crankshaft.