Rocker Arm Truss Structure for High-Speed Rigidity
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Solution Overview
Problem
Conventional rocker arms in internal combustion engines face challenges in achieving a balance between high rigidity and weight reduction, particularly when operating in high-speed rotation ranges, as increased rigidity through thicker walls leads to heavier components that are not suitable for high-speed use.
Innovation Solution
The rocker arm design features a plurality of arm portions with a connecting portion that includes a concave thinning portion along the axis direction of the pivot shaft, forming a triangular shape, which enhances rigidity while minimizing weight by thinning the outside and reinforcing the inside, allowing for a truss-like structure that supports loads effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the wall of each arm portion is thickened to enhance rigidity, then the rigidity of the rocker arm is improved, but the weight of the rocker arm increases making it unsuitable for high-speed rotation
Solution Approach 1:
The patent applies local quality by varying the wall thickness of the rocker arm in different regions. The wall is thinned in the swing trajectory area where less structural support is needed, while maintaining adequate thickness in load-bearing areas. This creates a non-uniform thickness distribution that reduces overall weight while preserving necessary rigidity for high-speed operation.
Solution Approach 2:
The patent introduces a new dimensional consideration by analyzing and optimizing the rocker arm structure in the swing trajectory dimension. By identifying and thinning the specific region where the connecting portion moves during swing, the design achieves weight reduction without compromising structural integrity in critical load-bearing dimensions.
2Weight of moving object
If the rocker arm is designed as a connection-type with multiple arm portions to reduce weight, then weight is reduced, but the molding accuracy and rigidity become insufficient leading to deformation during operation
Solution Approach 1:
The patent applies local quality by selectively thinning only the wall in the swing trajectory region while maintaining adequate wall thickness in other critical areas. This localized approach allows the connecting portion to be lighter for weight reduction, while other regions maintain sufficient thickness for molding accuracy and operational rigidity, preventing deformation during use.
3Strength
If the connecting portion is made heavier to limit deformation during operation, then the rigidity is improved, but the rocker arm cannot endure high-speed rotation due to increased weight
Solution Approach 1:
The patent applies local quality by creating a non-uniform thickness distribution in the connecting portion. The wall is thinned specifically in the swing trajectory area where mass reduction benefits high-speed rotation, while maintaining sufficient thickness in load-bearing regions to prevent deformation. This localized differentiation allows the rocker arm to achieve both high rigidity and high-speed capability.
Solution Approach 2:
The patent changes the physical parameter of wall thickness in the connecting portion by introducing a thinned region. This parameter change reduces the mass of the connecting portion, thereby reducing the rotational inertia and enabling the rocker arm to operate at higher speeds while maintaining adequate rigidity through strategic thickness distribution.
Data Source
AI summary
The disclosed structure achieves a desired balance between higher-rigidity and weight saving in a connection-type rocker arm which integrally rocks a plural of arm portions. The rocker arm has a plurality of arm portions integrally formed on a swinging base end side of the rocker arm which are forked and extend towards a swinging end of the rocker arm, a connecting portion which integrally connects each swinging end of the arm portions, and a concave thinning portion which overlaps a swinging trajectory of the connecting portion, when viewed in the axis direction of the pivot shaft of the rocker arm.