Engine Rocker Arm Decoupling Mechanism for Mass Reduction
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Solution Overview
Problem
Existing engine designs face challenges in reducing the equivalent mass of rocker arms while maintaining high acceleration and avoiding increased engine size, as increasing stiffness requires thicker structures, which in turn increases size and reduces mass efficiency.
Innovation Solution
The engine incorporates a decoupling device with a coupling pin, urging member, and actuator, where the coupling pin is partially inside the first coupling hole, and the urging member is between the receiver portion and the first rocker arm, allowing for a compact design that reduces the equivalent mass of the rocker arm without increasing engine size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of each rocker arm or peripheral structure is increased to obtain required stiffness, then the stiffness is improved, but the size of the engine increases
Solution Approach 1:
The rocker arm system is segmented into a first rocker arm and a second rocker arm that can be coupled or decoupled. This allows the system to achieve required stiffness when coupled while avoiding the need for continuously thick structures. The coupling pin and urging member further segment the stiffness requirement, providing it only when needed.
Solution Approach 2:
The system transitions from a static thick structure to a dynamic coupled/decoupled configuration. The urging member dynamically adjusts the coupling state based on operational requirements, providing stiffness only when necessary and reducing mass when the coupled state is not required.
2Speed
If the equivalent mass of each rocker arm is reduced to enable high acceleration, then the acceleration capability is improved, but the stiffness is reduced
Solution Approach 1:
The rocker arm system is divided into separate first and second rocker arms that can operate independently or together. This segmentation allows each arm to be lightweight for high acceleration while the coupling mechanism provides stiffness only when both arms need to work together.
Solution Approach 2:
The system dynamically adjusts its stiffness characteristics by coupling or decoupling the rocker arms based on operational demands. During phases requiring high acceleration, the arms can operate independently with reduced mass. When structural integrity is needed, they couple together through the coupling pin and urging member.
3Ease of manufacture
If the coupling pin structure is simplified for ease of manufacture, then the manufacturing is easier, but the reliability of preventing the coupling pin from coming off is reduced
Solution Approach 1:
The urging member automatically maintains the coupling pin in the engaged position by exerting continuous urging force. This self-service mechanism prevents the coupling pin from coming off without requiring complex external retention structures, simplifying manufacturing while ensuring reliability.
Solution Approach 2:
The urging member acts as an intermediary between the coupling pin and the rocker arms, providing the necessary retention force. This intermediary component simplifies the overall structure compared to complex mechanical interlocks while reliably preventing the coupling pin from disengaging.
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 configuration enables high acceleration of rocker arms with reduced equivalent mass, preventing the coupling pin from coming off and maintaining engine compactness, thus enhancing fuel efficiency without enlarging the engine.
Implementation Method 1
The urging member urges the coupling pin in a first direction
Implementation Method 2
The actuator presses the coupling pin in a second direction
Data Source
Figure 1
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Figure 3
AI summary
A coupling pin (51) includes a receiver portion (56) that receives an urging force applied by an urging member (52). The receiver portion (56) is located outside a first coupling hole (422). The urging member (52) is disposed between the receiver portion (56) and a first rocker arm (42). A cylinder head (4) includes a retainer portion (58) disposed downstream of the receiver portion (56) in a first direction (XI). The retainer portion (58) overlaps at least part of the coupling pin (51) as seen from an axis direction. The coupling pin (51) has a length (LI) greater than a distance (L2) between the first coupling hole (422) and the retainer portion (58) in the axis direction.