Variable Valve Mechanism Switch Pin Wear Reduction
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Solution Overview
Problem
Conventional variable valve mechanisms in internal combustion engines experience wear issues due to inappropriate timing during switching states, leading to excessive bending loads and uneven edge wear, which affects switching response.
Innovation Solution
The variable valve mechanism design modifies the sliding contact start to engage the return-side edge of the pin end surface instead of the idle-swing-side edge, ensuring the pressed center shifts toward the return direction without stopping, thereby reducing wear on both edges and minimizing excessive bending loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressing surface comes in contact with the lower edge of the pin end surface at sliding contact start time, then the switch pin can be pushed back to the disconnected position, but an excessive bending load is applied to the switch pin
Solution Approach 1:
The pressing surface is designed to contact the pin end surface at a position above the lower edge before the sliding contact fully engages. This preliminary contact position allows the switch pin to be gradually pushed back without sudden excessive bending loads, while still achieving the disconnected position switching function
2Reliability
If the pressed center remains at the upper edge during sliding contact, then the switch arm can push back the switch pin effectively, but the upper edge wears easily and adversely affects switching response
Solution Approach 1:
The pressing surface is designed with a curved profile that dynamically shifts the pressed center position during sliding contact. The pressed center moves from the upper edge toward the middle of the pin end surface, distributing wear across multiple areas rather than concentrating it at the upper edge, while maintaining effective push-back force throughout the motion
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
In a variable valve mechanism, during switching from a disconnected state to a connected state, the switch arm being displaced in a return direction comes in sliding contact with a pin end surface of the switch pin, and presses the pin end surface toward the disconnected position to push back the switch pin. At a sliding contact start time, the switch arm sliding contacts a portion of the pin end surface on a return direction side with respect to an idle-swing-side edge. At least during a period from a 10% position time to a sliding contact end time, a position of a pressed center relative to the pin end surface shifts toward the return direction side without stopping as the switch arm is displaced toward the return direction relative to a main arm, so that the sliding contact ends without stopping of the pressed center at a return-side edge.