Adjustable Cam Profile Generation via Pre-Machining
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Solution Overview
Problem
Existing camshaft grinding methods fail to prevent profile jumps and increased wear due to manufacturing tolerances and play between cam elements, leading to unwanted valve lift and accelerated wear of components.
Innovation Solution
A method for generating a cam profile on a camshaft with an adjustable cam assembly, where the adjusting cam element is machined with a continuous diameter reduction and positioned to spread apart from the fixed cam element during machining, ensuring a smooth transition and avoiding profile jumps by reducing the adjusting cam base circle diameter to less than the fixed cam nominal circle diameter minus double the tolerance, allowing the pick-off element to contact only the fixed cam base circle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the adjusting cam element is machined after assembly with the fixed cam element, then manufacturing precision can be improved, but profile jumps occur due to play between cam elements
Solution Approach 1:
The adjusting cam element is pre-machined before assembly, and the fixed cam element is pre-positioned on the shaft. This preliminary action allows the adjusting cam to be machined in a controlled state without play, preventing profile jumps while maintaining manufacturing precision
Solution Approach 2:
The camshaft is divided into separate components (adjusting cam element, fixed cam element, shaft) that are processed independently before assembly. The adjusting cam element is machined separately and then assembled, allowing precise control of each component's geometry without interference from play between parts
2Manufacturing precision
If the adjusting cam element is locked in position during machining, then manufacturing precision is maintained, but the cam assembly loses adjustability
Solution Approach 1:
The adjusting cam element is pre-machined to its final contour before assembly, ensuring manufacturing precision. After assembly, the adjusting cam can be rotated relative to the fixed cam element to achieve the desired adjustment, maintaining adaptability
Solution Approach 2:
The cam assembly is designed to be static during machining (adjusting cam locked in position) and dynamic during operation (adjusting cam rotatable relative to fixed cam). This allows manufacturing precision to be maintained while preserving adjustability functionality
3Manufacturing precision
If manufacturing tolerances and play between cam elements are reduced, then cam profile accuracy improves, but device complexity increases
Solution Approach 1:
The play and tolerances between cam elements are eliminated by extracting the adjusting cam element from the assembled state and machining it separately in a pre-assembled, play-free configuration. This removes the source of inaccuracy without requiring tighter tolerances on all components
Solution Approach 2:
The invention introduces an intermediary machining state where the adjusting cam element is held in position relative to the fixed cam element during machining, but not permanently locked. This intermediary state allows accurate machining while preserving the ability to adjust the cam element after assembly
Data Source
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AI summary
The invention relates to a method for producing a cam profile of a cam pack of a cam shaft, said cam pack having at least two cam elements that can be adjusted in relation to each other, and to a camshaft, wherein the camshaft comprises an outer shaft, an inner shaft arranged concentrically within the outer shaft in such a way that the inner shaft can be rotated, and at least one fixed cam element connected to the outer shaft for conjoint rotation and one adjustment cam element connected to the inner shaft for conjoint rotation, wherein the method comprises at least the following steps: processing an adjustment cam contour of the adjustment cam element by means of the continuous diameter reduction of at least one segment of the adjustment cam base circle, wherein the adjustment cam base circle is reduced to a diameter that is smaller than a fixed cam nominal circle diameter minus a doubled adjustment cam base circle tolerance, and processing a fixed cam contour of the fixed cam element by reducing a fixed cam contour protrusion at least in a region between a transition point, upon the reaching of which a tapping element for converting a revolving motion of the cam elements into a linear motion of the valves is transferred from the fixed cam element to the adjustment cam element, and is placed to a processing point.