Variable Valve Mechanism Output Arm Bouncing Restraint
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Solution Overview
Problem
Conventional variable valve mechanisms face issues with output arm bouncing due to the absence of a no-lift cam or lobe, leading to instability and increased manufacturing costs, as the camshaft must accommodate these projections to prevent bouncing.
Innovation Solution
A variable valve mechanism with a camshaft having a general shaft part and a cam part, where the output arm has a great height to maintain a clearance of 3 mm or less with the general shaft part, preventing further bouncing by contacting the shaft during uncoupling and eliminating the need for projections like no-lift cams or lobes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the camshaft is provided with projections such as no-lift cam or lobe to prevent output arm bouncing, then the stability of the output arm is improved, but the manufacturing cost and mass of the camshaft increase
Solution Approach 1:
The invention extracts the bouncing-prevention function from the camshaft projections and transfers it to the output arm structure itself. By providing a projection on the output arm that contacts the camshaft shaft part, the bouncing is prevented without requiring complex projections on the camshaft, thus simplifying camshaft manufacturing while maintaining stability.
Solution Approach 2:
Instead of modifying the camshaft to prevent bouncing (conventional approach), the invention inverts the approach by modifying the output arm to interact with the camshaft shaft part. This inversion eliminates the need for costly camshaft projections while achieving the same stability goal.
2Stability of the object's composition
If the output arm height is increased to maintain small clearance with the camshaft shaft part, then the bouncing restraint is improved, but the device complexity increases
Solution Approach 1:
The invention applies local quality by providing a projection only on the output arm at the specific location where it contacts the camshaft shaft part. This localized modification achieves bouncing restraint without requiring complex changes to the entire output arm structure or other mechanism components.
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 configuration reduces manufacturing costs and mass by preventing output arm bouncing through contact with the camshaft's general shaft part, enhancing stability and eliminating the need for costly projections.
Implementation Method 1
the output arm 93 uncoupled from the input arm 92 bounces due to the elastic force of a valve spring 8
Data Source
AI summary
A variable valve mechanism of an internal combustion engine includes a camshaft having a general shaft part and a cam part arranged next to each other in an axial direction, an input arm that swings when pressed by the cam part, an output arm that is swingably mounted and that drives a valve when swinging, and a switch device that switches the variable valve mechanism between a coupled state where the input arm and the output arm are coupled to swing together and an uncoupled state. The output arm has a great height so that clearance between the output arm and the general shaft part is 3 mm or less when the variable valve mechanism is in the coupled state and the valve is closed. If the output arm bounces in the uncoupled state, the output arm comes into contact with the general shaft part through the clearance.