SOHC Variable Valve Gear Axial Pin Actuation
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Solution Overview
Problem
The existing SOHC engines with variable valve gears face an increase in size due to the direct actuation of pin members, which complicates the compact arrangement of the valve gear.
Innovation Solution
A single cylinder engine design incorporating a switching pin member and actuator that moves in the axial direction of the cam shaft, linking and unlinking rocker arms to achieve a variable valve gear while minimizing the engine's size by optimizing the placement and movement of the switching pin member and actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a variable valve gear is realized with a simple configuration by directly pressurizing a pin member by an actuator, then the device complexity is reduced, but the engine size increases
Solution Approach 1:
The patent repositions the switching pin member from a conventional location to be positioned on the end section side of the valve with respect to the rocker shaft. This spatial reconfiguration in the axial direction of the cam shaft allows the pin member to be actuated without increasing the radial dimensions of the engine, thereby reducing overall engine size while maintaining the variable valve gear functionality
Solution Approach 2:
The switching pin member is designed to be movable between a first position (linking first and second rocker arms) and a second position (not linking them). This dynamic positioning allows the valve gear to switch between different operating modes (single valve and dual valve operation), providing variable valve control without requiring a complex multi-component system
2Adaptability or versatility
If a switching pin member is added to realise a variable valve gear, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The switching pin member serves multiple functions: it acts as a linkage between rocker arms when in the first position, and serves as an actuation point for the rod when in the second position. This multi-functionality allows a single component to provide both structural linkage and actuation control, reducing the need for additional separate components and maintaining system simplicity while achieving variable valve operation
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 design allows for a compact SOHC engine with a variable valve gear by reducing the size of the cylinder section and actuator, thereby minimizing the overall engine size and improving fuel efficiency.
Implementation Method 1
The actuator switches the position of the switching pin member between the first position and the second position by pressurizing the switching pin member in the axial direction of the cam shaft
Implementation Method 2
The switching pin member links the first rocker arm and the second rocker arm at the first position and swings together with the first rocker arm and the second rocker arm
Data Source
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AI summary
A first rocker arm (36) is supported by a rocker shaft (33) and is provided to be able to operate a valve (24-27). A second rocker arm (37) is supported by the rocker shaft (33) and is arranged to line up with the first rocker arm (36) in the axial direction of a cam shaft (14). A switching pin member (35) is able to be moved in the axial direction of the cam shaft (14), and links the first rocker arm (36) and the second rocker arm (37) at a first position and swings together with the first rocker arm (36) and the second rocker arm (37). The switching pin member (35) is positioned on an end section side of the valve with regard to the rocker shaft when viewed from the axial direction of the cam shaft.