Variable Valve Cam Lobe Oscillation Control
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Solution Overview
Problem
Existing variable valve apparatuses for internal combustion engines face issues with drastic motion of the cam lobe member relative to the cam base member, leading to collision sounds during low revolution operations due to insufficient spring bias force, which affects the valve lift mechanism.
Innovation Solution
A variable valve apparatus with a cam lobe member having a main cam part and a push part at different positions, an elastic member for biasing, and a fixation mechanism that allows the cam lobe member to move between two positions, with the push part being designed to smoothly oscillate and prevent drastic motion by optimizing its shape and position relative to the cam base member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the spring bias force is increased to prevent drastic motion of the cam lobe member, then the collision sound is reduced, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The cam lobe member is divided into two distinct parts: a main cam part that contacts the rocker arm for valve operation, and a push part that interacts with the guide groove for controlled motion. This segmentation allows the push part to be optimized specifically for smooth oscillation while the main cam part maintains its valve-lifting function, thereby reducing collision sounds without requiring increased spring force or complex additional components.
Solution Approach 2:
The guide groove is designed with specific local geometric characteristics (width, depth, curvature) that are optimized for the push part of the cam lobe member. This local optimization of the groove geometry creates a smooth oscillation path that prevents drastic motion and collision sounds, while leaving the rest of the cam mechanism unchanged and simple.
2Device complexity
If the cam lobe member is allowed to oscillate freely between positions, then the valve lift mechanism is simplified, but collision sounds occur due to drastic motion
Solution Approach 1:
By segmenting the cam lobe member into a main cam part and a push part, the invention enables free oscillation between positions (maintaining simplicity) while the push part's interaction with the guide groove ensures smooth motion transitions. The guide groove's geometry constrains the push part to follow a controlled path, preventing collision sounds during position transitions.
Solution Approach 2:
The guide groove acts as an intermediary element between the push part of the cam lobe member and the cam base member. It mediates the oscillation motion by providing a geometrically optimized path that smooths out the transitions between positions, thereby preventing direct impact and collision sounds while maintaining the simplicity of the overall mechanism.
3Volume of moving object
If the push part is positioned closer to the main cam part, then the structure is more compact, but the oscillation smoothness is reduced
Solution Approach 1:
The guide groove is designed with specific local geometric characteristics (width, depth, curvature) that are optimized for the push part's oscillation motion. This local optimization ensures smooth oscillation even when the push part is positioned close to the main cam part, as the groove geometry provides the necessary guidance and cushioning for smooth transitions.
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 apparatus effectively inhibits drastic motion of the cam lobe member, reducing collision sounds and improving valve operation by allowing smooth transition between positions, enhancing the flexibility and efficiency of the valve lift mechanism.
Implementation Method 1
an elastic member configured to bias the cam lobe member toward the first position
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
An variable valve apparatus for an internal combustion engine according to the invention includes a cam base member (10), an elastic member (18), a cam lobe member (12), and a mechanism for fixing the cam lobe member to the cam base member. The cam lobe member (12) includes a main cam part (12d), and a push part (12e) provided at a different position than the main cam part. The cam lobe member can move relative to the cam base member, between a first position at which the push part (12e) protrudes from the cam base member and a second position at which the main cam part protrudes from the cam base member. The cam lobe member is biased toward the first position by the elastic member. When the push part is pushed by a follower member linked to an engine valve, the cam lobe member can move toward the second position side.