Engine Valve Synchronization Cam Prevents Flip Phenomenon
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Solution Overview
Problem
Conventional valve mechanisms for engines experience a 'flip phenomenon' where the connected state between rocker arms is abruptly canceled when the intake or exhaust valve is not closed, leading to potential damage due to impact loads, as the slide pin is insufficiently fitted or the frictional force becomes too small, causing the rocker arms to swing improperly.
Innovation Solution
A valve mechanism that includes a synchronization cam, a cam follower, and a positioning mechanism with concave portions to ensure the transmission component moves reliably between predetermined positions, preventing the flip phenomenon by engaging the pressing element with concave portions and using a spring-biased pressing element to position the transmission component accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the slide pin is used to connect rocker arms without a positioning mechanism, then the switching mechanism can operate with simpler structure, but the slide pin may move insufficiently or experience insufficient frictional force causing the flip phenomenon
Solution Approach 1:
The positioning mechanism acts as an intermediary between the slide pin and rocker arms, providing precise positioning and maintaining reliable connection. The pressing element with spring bias serves as a mediator that ensures the transmission component remains firmly engaged with the rocker arms, preventing the flip phenomenon while maintaining operational reliability.
Solution Approach 2:
The positioning mechanism performs preliminary positioning of the transmission component before the rocker arms begin to swing. By pre-establishing the correct position and engagement of the slide pin with the rocker arms, the system ensures proper connection is established in advance, preventing insufficient fitting and the resulting flip phenomenon.
2Ease of operation
If the transmission component moves freely without positioning constraints, then the switching mechanism operates more smoothly, but the transmission component may move at incorrect times or amounts causing improper rocker arm swing
Solution Approach 1:
The positioning mechanism controls the position parameter of the transmission component precisely. By using the pressing element and spring bias, the system maintains the transmission component at the correct position with accurate engagement depth, ensuring both smooth operation and precise positioning without allowing incorrect movement.
3Reliability
If the pressing element engages deeply with the transmission component, then the positioning is more secure, but the transmission component cannot move freely causing operational restrictions
Solution Approach 1:
The positioning mechanism transitions from a static engagement to a dynamic one. The spring-biased pressing element allows the transmission component to move freely during normal operation while maintaining secure positioning when needed. The spring bias provides continuous contact force that adapts to operational requirements, ensuring both movement freedom and positioning security.
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
The solution ensures the transmission component operates only at a predetermined operation amount and time, preventing the flip phenomenon and maintaining stable valve operation, thus avoiding damage to the intake or exhaust valves and the switching pins.
Implementation Method 1
a synchronization cam, a cam follower, and a positioning mechanism with concave portions to ensure the transmission component moves reliably between predetermined positions
Implementation Method 2
a positioning mechanism that includes a spring-biased pressing element that engages with a concave portion formed in the transmission component, and positions the transmission component at a predetermined position defined by the concave portion
Implementation Method 3
If a frictional force generated at the contact portion between the slide pin and the hole wall surface of the pin hole is large, the movement of the slide pin is regulated by the frictional force
Data Source
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AI summary
A valve mechanism for an engine includes a camshaft, a rocker arm (9), a synchronization cam (13) configured to rotate in synchronism with a valve driving cam, and a switching mechanism (3) configured to switch the driving state of an intake valve or an exhaust valve (5) when a cam follower (22) is pressed by the synchronization cam (13). The synchronization cam (13) presses the cam follower (22) at a time when the intake valve or the exhaust valve is closed. The switching mechanism (3) includes a switching unit (21) configured to switch the driving state when a switching component (21A) that is one of components constituting a valve mechanism system moves, a driving unit (23) configured to drive the switching component (21A) via a transmission component (25), and a positioning mechanism (24) including a spring-biased pressing element (82) configured to engage with a concave portion (81) of the transmission component (25). The concave portion (81) is formed by a first concave portion (81a) with which the pressing element (82) engages in a first driving state, and a second concave portion (81b) with which the pressing element (82) engages in a second driving state. A positioning interval between the first concave portion (81a) and the second concave portion (81b) is greater than the moving amount of the transmission component (25) when the transmission component (25) is driven by the synchronization cam (13) and moves. It is possible to provide the valve mechanism for an engine in which the transmission component configured to switch the driving state of the intake valve or the exhaust valve operates only in a predetermined operation amount at an appropriate time, a flip phenomenon does not occur.