Cam Element Undercut for Valve Lift Switching
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Solution Overview
Problem
Existing cam elements for valve train devices in internal combustion engines are complex to produce and require intricate machining processes, especially when featuring overlapping partial cams for valve lift switching.
Innovation Solution
The introduction of an undercut with a truncated cone shape between the partial cams, offset from the rotational axis, simplifies manufacturing and maintains switchability by allowing a shallow angle transition, facilitating efficient production and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If overlapping partial cams are used for valve lift switching, then valve train functionality is improved, but manufacturing complexity increases
Solution Approach 1:
The cam element is divided into multiple partial cams (first partial cam and second partial cam) that are arranged axially adjacent to each other. Each partial cam has a different cam contour for controlling valve lift in different switching positions. This segmentation allows the cam element to provide multiple valve lift characteristics while maintaining a relatively simple overall structure that is easier to manufacture than a single complex cam.
2Manufacturing precision
If traditional machining processes are used for overlapping partial cams, then manufacturing precision can be maintained, but production time and cost increase
Solution Approach 1:
An undercut is introduced between the two partial cams during the manufacturing process. This undercut serves as a preliminary feature that facilitates subsequent machining operations and assembly. By preparing this clearance feature in advance, the manufacturing process becomes more efficient and less time-consuming while maintaining the required precision of the cam contours.
Solution Approach 2:
The undercut acts as an intermediary feature between the two partial cams, providing necessary clearance for machining tools and facilitating the manufacturing process. This intermediate structure enables more efficient production by allowing tools to access and machine the cam contours without interference, thereby improving productivity while maintaining manufacturing precision.
3Ease of manufacture
If undercut is introduced between partial cams, then manufacturing ease is improved, but tool access clearance is required
Solution Approach 1:
Material is removed to create an undercut between the two partial cams. This extracted feature provides the necessary clearance for machining tools to access and machine the cam contours effectively. By taking out this portion of material, the manufacturing process becomes simpler and more efficient, outweighing the minor increase in geometric complexity.
Data Source
Figure 1
Figure 2~3
AI summary
The invention is based on a cam element for a valve-gear device of an internal combustion engine, with at least one cam (10) which has at least two partial cams (11, 12) which are arranged next to one another, have a common base circle phase in at least one angular range (13) of the cam shaft and are provided for switching over a valve lift by displacing a cam follower from one of the partial cams (11, 12) to another of the partial cams (11, 12). It is proposed that the partial cams (11, 12) have an overlapping arrangement.