Variable Valve Train Cam Follower Switching Mechanism
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Solution Overview
Problem
Existing variable valve trains for internal combustion engines face inefficiencies due to the large mass of cam carriers, which hinder fast switching between different cam profiles, affecting speed and performance.
Innovation Solution
A compact variable valve train design featuring a pivotably mounted bracket with a cam follower that can follow different cam contours, utilizing a transmission lever with a pivot axis and a support component for axial displacement, allowing quick switching between cam profiles without the need for additional non-rotatable connection means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cam carrier with double cam is used to enable switching between different cam profiles, then valve train versatility is improved, but the mass of the moving component increases, which deteriorates switching speed
Solution Approach 1:
The invention divides the cam carrier into two separate components: a stationary camshaft with cams and a movable holder with cam follower. This segmentation allows the holder to be lightweight and move quickly between positions, while the cams remain fixed on the camshaft, thus resolving the contradiction between versatility and switching speed.
Solution Approach 2:
The cam follower is extracted from the heavy cam carrier structure and placed on a separate lightweight holder. This extraction allows the holder to achieve fast switching speeds while the cams remain on the stationary camshaft, maintaining the versatility of multiple cam profiles without the mass penalty.
2Speed
If a compact holder design is used to reduce mass, then switching speed is improved, but the structural complexity increases due to pivotable mounting requirements
Solution Approach 1:
The invention combines the pivotable mounting function directly into the holder component itself, rather than requiring separate mounting mechanisms. The holder is designed with integrated pivot axes that allow it to rotate between positions, simplifying the overall structure while maintaining compact dimensions and fast switching capability.
Solution Approach 2:
Instead of making the entire cam carrier pivotable (which would be complex and heavy), the invention inverts the approach by keeping the camshaft stationary and making only the small holder pivotable. This inversion dramatically reduces structural complexity while achieving the same functional result.
Data Source
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AI summary
The invention relates to a variable valve train (10) for an internal combustion engine. The variable valve train (10) comprises at least one poppet valve (16) and a camshaft (12) having a first cam (18) and a second cam (20) arranged offset in a longitudinal direction of the camshaft (12). The variable valve train (10) further comprises a transmission lever (14) which is operatively connected between the at least one poppet valve (16) and the camshaft (12) for actuating the at least one poppet valve (16). The transmission lever (14) has a pivot axis (22), a bracket (26), and a cam follower (28). The bracket (26) is pivotably mounted about the pivot axis (22). The bracket (26) holds the cam follower (28).The bracket (26) is mounted to be axially displaceable parallel to the pivot axis (22) and/or parallel to the camshaft (12), so that the cam follower (28) can optionally follow the cam contour of the first cam (18) or the cam contour of the second cam (20).