Variable Valve Actuator Positioning for Heat and Size Reduction
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Solution Overview
Problem
The existing engine design with a variable valve gear faces challenges in reducing size while minimizing the impact of combustion chamber heat on the actuator, leading to increased engine size due to the actuator's placement near the combustion chamber.
Innovation Solution
The engine design incorporates a switching pin member that can move between two positions, with the actuator positioned on the opposite side of the cam chain chamber, attached to the head cover, and the rod supported by the head cover, reducing heat exposure and drive force requirements, thereby minimizing engine size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the actuator is arranged at a position close to the pin member to reduce rod length and actuator size, then the engine size is reduced, but the actuator is exposed to heat from the combustion chamber
Solution Approach 1:
The actuator is positioned in the axial direction of the cam shaft, utilizing the vertical space dimension to place it close to the pin member for compactness, while the rod extends horizontally to connect to the rocker arm mechanism, creating a spatial arrangement that minimizes heat exposure while maintaining mechanical efficiency
2Object-affected harmful factors
If the actuator is attached to the cylinder head and head cover via an attachment plate to reduce heat exposure, then the heat effect on the actuator is reduced, but the engine size is increased
Solution Approach 1:
The actuator is integrated with the head cover structure, merging the actuator mounting function into the existing head cover component. This eliminates the need for separate attachment plates and reduces the overall number of parts, thereby reducing engine size while maintaining adequate heat protection through the head cover's structural position
Data Source
AI summary
An actuator (39) switches the position of a switching pin member (35) between a first position and a second position by pressurizing the switching pin member in the axial direction of a cam shaft (14). At least a portion of the switching pin member (35) overlaps with a head cover (7) when viewed from the axial direction of the cam shaft (14). The actuator (39) is arranged on the opposite side to a cam chain chamber (16) with regard to the cam shaft (14) in the axial direction of the cam shaft. The actuator (39) is arranged outside of an engine (1). The actuator (39) is positioned more to the head cover (7) side than an end section of a cylinder head (6).