Hollow Camshaft Nested Latching for Axial Positioning

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Solution Overview

Problem

Existing camshafts with hollow support shafts face challenges in integrating displaceable cam segments due to space constraints for latching means, which affects the load-bearing capacity and stability of the camshaft.

Innovation Solution

The latching means is arranged at least partially inside the inner shaft, allowing sufficient space for locking mechanisms without compromising the load-bearing capacity, enabling precise axial positioning and flexible control of cam segments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the latching means is arranged outside the inner shaft in existing camshafts, then the locking mechanism can be accessed and installed, but the space constraints compromise the load-bearing capacity and stability of the camshaft

Engineering Contradiction:
Improveload-bearing capacityVSAvoidaccessibility of locking mechanism
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The latching means is nested inside the inner shaft, with the latching element arranged within the hollow interior space of the inner shaft. This nesting arrangement allows the locking mechanism to be housed within the existing structural components, eliminating the need for external mounting space while maintaining full load-bearing capacity of the camshaft structure.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Adaptability or versatility

If the cam segment is made axially displaceable to enable switching between different cam contours, then the adaptability to engine operating conditions is improved, but the structural complexity and space requirements increase

Engineering Contradiction:
Improveadaptability to engine conditionsVSAvoidstructural complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The cam segment is designed with axial displacability, transitioning from a fixed position to a dynamically adjustable position along the axial direction. This allows the cam segment to switch between different cam contours (first cam contour and second cam contour) by moving axially, enabling adaptation to different engine operating conditions such as varying speeds and loads while maintaining a relatively simple overall structure.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If the inner shaft is made rotatable relative to the support shaft, then the angular positioning of cam segments can be varied for variable valve timing, but the precision of axial positioning becomes more difficult to maintain

Engineering Contradiction:
Improvevariable valve timing capabilityVSAvoidaxial positioning precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The camshaft is segmented into distinct functional components: the support shaft, the rotatable inner shaft, and the axially displaceable cam segment. This segmentation allows the inner shaft to rotate independently for timing adjustment while the cam segment maintains precise axial positioning through its dedicated displacement mechanism, with each component performing its specific function without interfering with the precision requirements of the other.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3146166B1Camshaft
Publication Date: 2020.05.06 THYSSENKRUPP PRESTA TECCENTER AG
  • EP3146166B1 patent drawingFigure 1~2
  • EP3146166B1 patent drawingFigure 3~4
  • EP3146166B1 patent drawingFigure 5~6

AI summary

The invention relates to a camshaft (1) with a support shaft (3) which is designed as a hollow shaft and in the interior of which an inner shaft (5) is arranged concentrically to the support shaft (3). The inner shaft (5) can be rotated relative to the support shaft (3). Furthermore, a first cam segment (7) with a first recess (9) for receiving the support shaft (3) is arranged on the support shaft (5), said cam segment being rotatable with respect to the support shaft (3) and being connected to the inner shaft (5) in a rotationally and axially fixed manner by means of a connection means (17). Additionally, A second cam segment (25) with a second recess (27) for receiving the support shaft (3) is arranged on the support shaft (3). The second cam segment (25) has at least two cam contours (29, 31) and is secured on the support shaft (3) such that the second cam segment (25) is connected to the support shaft (3) in a rotationally fixed manner and is arranged on the support shaft (3) in an axially movable manner.