Assembled Camshaft Tooth Profile for Hub Alignment and Fixation
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Solution Overview
Problem
Existing built camshafts for internal combustion engines face issues with temperature-related stress and damage due to thermal joining methods, and the need for precise angular alignment of hubs without damaging external teeth during assembly.
Innovation Solution
A camshaft design featuring a basic shaft with external toothing and a hub with internal toothing, where the external toothing has alternating tooth gaps of different widths to form a sliding fit and axial fixation, allowing for rotational and angular alignment without a positive connection, thereby minimizing damage and ensuring secure assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bearing rings are joined by interference fit or thermal joining to the external gearing, then the hub is securely fixed axially and rotationally, but large temperature differences act on the camshaft components and may cause damage
Solution Approach 1:
The patent extracts the harmful thermal joining process from the assembly method. Instead of using interference fit or thermal joining that causes temperature stress, the invention uses a press fit method where the hub is pressed onto the base shaft at ambient temperature, eliminating thermal stress while maintaining secure fixation through the frictional and positive-locking sub-regions of the gearing
Solution Approach 2:
The patent replaces the thermal joining mechanism with a mechanical press fit mechanism. The hub is fixed to the base shaft through mechanical friction and positive locking features of the gearing rather than through thermal expansion and contraction, substituting a potentially harmful thermal process with a safer mechanical process
2Ease of manufacture
If the hub is pushed over the external gearing during assembly, then the hub can be positioned on the base shaft, but the external teeth may be damaged
Solution Approach 1:
The patent segments the gearing into distinct functional sub-regions: a frictional-locking sub-region for axial fixation and a positive-locking sub-region for rotational fixation. This segmentation allows the hub to be assembled smoothly through the frictional region without damaging the teeth, while the positive-locking region provides secure engagement without requiring forceful pushing that could damage the external gearing
Solution Approach 2:
The patent applies different local qualities to different portions of the gearing. The frictional-locking sub-region has properties suitable for smooth assembly (friction-based engagement), while the positive-locking sub-region has properties for secure fixation (form-fit engagement). This local differentiation allows easy assembly while protecting the external teeth from damage
3Strength
If the hub is connected rotationally fixed to the base shaft, then torque can be transmitted, but the hub cannot be aligned in the desired angular position
Solution Approach 1:
The patent creates a dynamic assembly process where the hub transitions from a movable state during alignment to a fixed state for torque transmission. During assembly, the hub can rotate freely through the positive-locking sub-region to achieve the desired angular position. Once positioned, the frictional-locking sub-region engages to fix the hub axially and rotationally, enabling torque transmission while maintaining the desired angular alignment
Data Source
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AI summary
The invention relates to an assembled camshaft (1) for an internal combustion engine, wherein the camshaft (1) comprises a main shaft (2) and an outer toothing (3) extending axially along the main shaft (2) at least in sections, as well as at least one hub (10) having an inner toothing (8) which corresponds with the outer toothing (3) of the main shaft (2) in such a way that the hub (10) is connected to the main shaft (2) in a rotationally and axially fixed manner, wherein the outer toothing (3) has at least one interlocking sub-region (5) or force-locking sub-region (6) extending axially along the main shaft (2) at least in sections, in order to at least interlockingly or force-lockingly arrange the hub (10), and wherein at least one aligning region (7) extending axially along the main shaft (2) at least in sections is connected at least to the interlocking sub-region (5) or force-locking sub-region (6) for angular alignment of the hub (10). The invention also relates to a method for producing an assembled camshaft (1) of this type.