Actuator Mounting on Straddled Vehicle Head Cover
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Solution Overview
Problem
Conventional straddled vehicles with variable valve mechanisms face challenges in reducing engine size while maintaining effective cooling, as the actuator's placement on the cylinder head increases the engine's height, leading to interference with tool paths and larger fore and aft dimensions, and hampers heat radiation due to its position between main frames.
Innovation Solution
Attaching the actuator to the head cover instead of the cylinder head, allowing the cylinder head to be lowered, and inclining the cylinder unit to position the actuator outside the main frames, enabling efficient heat dissipation and reducing engine size without compromising performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the actuator is attached to the cylinder head, then the variable valve mechanism can be implemented, but the cylinder head becomes large-sized and the engine size increases
Solution Approach 1:
The actuator is relocated from the vertical dimension (attached to the top of the cylinder head) to the horizontal dimension (attached to the side wall of the cylinder head). This dimensional change allows the actuator to be positioned without increasing the vertical height of the cylinder head, thereby reducing the overall engine size while maintaining the variable valve mechanism functionality.
2Ease of manufacture
If the peripheral wall portion of the cylinder head is made high to attach the actuator, then the actuator can be mounted, but the fore and aft size of the cylinder head increases due to interference with tool paths
Solution Approach 1:
Instead of increasing the vertical height of the peripheral wall portion to mount the actuator, the actuator is mounted on the side wall in a horizontal arrangement. This avoids the need to extend the front and rear walls to accommodate tool paths, thereby reducing the fore and aft size of the cylinder head while still providing a mounting surface for the actuator.
3Volume of stationary object
If the actuator is attached to the head cover, then the cylinder head size can be reduced, but the actuator may overlap with main frames and heat radiation may be hampered
Solution Approach 1:
The actuator is positioned on the side wall of the cylinder head, utilizing the lateral space between the cylinder head and the main frames. This horizontal positioning allows the actuator to be located in a region where it does not overlap with the main frames, ensuring adequate space for heat radiation and cooling while maintaining a compact cylinder head design.
4Ease of manufacture
If the actuator is positioned between the main frames, then mounting is simplified, but heat radiation is hampered due to restricted airflow
Solution Approach 1:
The actuator is extracted from the confined space between the main frames and repositioned on the side wall of the cylinder head. This extraction removes the actuator from the heat-trapping region, allowing heat to dissipate more effectively without being blocked by the main frames, while still maintaining ease of mounting through the side wall attachment.
Data Source
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AI summary
A body frame (3) is not disposed forward of a front wall of each of a cylinder member (35), a cylinder head (41), and a head cover (45), and does not overlap each front wall of the cylinder member (35), cylinder head (41), and head cover (45) in the front view of the vehicle. An actuator body (73) is attached to the head cover (45). The actuator body (73) has a center (P) thereof located rearward of a cylinder axis (L) in the side view of the vehicle. A cylinder unit (33) is inclined so that the actuator body (73) overlap neither a right main frame (6R) nor a left main frame in the side view of the vehicle.