Nested Camshaft Valve Train for Sequential Lift Switching
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Solution Overview
Problem
Existing valve train devices for internal combustion engines are costly to produce due to complex cam designs and require intricate manufacturing processes, particularly for camshafts with multiple cam curves, which complicates the production and maintenance of valve lift switching mechanisms.
Innovation Solution
A valve drive device with a two-stage sequential valve lift switching mechanism, featuring a first camshaft unit with an outer shaft and primary cams, a second camshaft unit with an inner shaft and secondary cams, and an adjustment unit that allows for axial displacement of the inner shaft, enabling simple and cost-effective switching of valve lifts by using multi-part shaft elements and a shift gate for sequential displacement, thereby reducing production costs and simplifying maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If complex cam designs with multiple cam curves are used to achieve valve lift switching, then the valve train device can provide multiple valve lift profiles, but the manufacturing cost and production complexity increase significantly
Solution Approach 1:
The camshaft is divided into two separate units: a first camshaft unit with primary cams and a second camshaft unit with secondary cams. Each cam unit has a simpler cam profile, avoiding the need for complex multi-curve cams. The combination of these two simpler cam units achieves the valve lift switching function, reducing manufacturing complexity and cost while maintaining adaptability.
Solution Approach 2:
The patent combines two separate camshaft units (primary cams and secondary cams) to achieve the function of multiple valve lift profiles. By merging the actions of these two simpler cam units through the adjusting unit, the system achieves versatile valve lift control without requiring individually complex cams, thus reducing manufacturing cost.
2Adaptability or versatility
If complex cam designs with multiple cam curves are used to achieve valve lift switching, then the valve train device can provide multiple valve lift profiles, but the production and maintenance complexity increase
Solution Approach 1:
The camshaft system is segmented into two independent units with simpler individual cam profiles. This segmentation reduces the complexity of designing and manufacturing each cam while maintaining the overall capability for multiple valve lift profiles through their combined action.
Solution Approach 2:
The patent introduces an adjusting unit that dynamically adjusts the relative position between the first and second camshaft units. This dynamic adjustment mechanism enables switching between different valve lift profiles without requiring statically complex cam designs, simplifying production while maintaining versatility.
3Adaptability or versatility
If traditional valve lift switching mechanisms are used, then valve lift can be switched, but the mechanism requires complex coupling and increases installation space and weight
Solution Approach 1:
The adjusting unit merges the adjustment functions for both camshaft units into a single integrated mechanism. This consolidation achieves valve lift switching capability while reducing the overall weight compared to traditional separate adjustment mechanisms, as the adjusting unit simultaneously controls the relative positioning of both cam units.
4Adaptability or versatility
If traditional valve lift switching mechanisms are used, then valve lift can be switched, but the mechanism requires complex coupling and increases installation space
Solution Approach 1:
The second camshaft unit is nested within the first camshaft unit, with the inner shaft of the second unit guided in the outer shaft of the first unit. This nested arrangement compactly integrates both camshaft units and the adjusting unit, enabling valve lift switching while minimizing installation space compared to traditional separate mechanisms.
Data Source
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AI summary
The invention relates to a valve train device, in particular an internal combustion engine valve train device, having a first camshaft unit, which comprises an external shaft (10a; 10b) and primary cams (11a, 12a, 13a, 14a; 11b, 12b, 13b, 14b, 11b', 12b', 13b', 14b') connected to the external shaft (10a; 10b), having a second camshaft unit, which comprises an inner shaft (15a; 15b) guided in the external shaft (10a; 10b) and secondary cams (16a, 17a, 18a, 19a; 16b, 17b, 18b, 19b, 16b', 17b', 18b', 19b') connected to the inner shaft (15a; 15b), and having an adjustment unit (22a; 22b), which is provided for adjusting the two camshaft units against one another. It is proposed that the adjustment unit (22a; 22b) is used for providing an at least two-stage sequential valve lift switching.