Camshaft Tolerance Compensation via Integral Oldham Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing adjustable camshafts face challenges in tolerance compensation between the rotor and stator, leading to potential jamming and inefficiencies due to manufacturing and assembly inaccuracies, which can result in incomplete torque transmission.
Innovation Solution
The implementation of an Oldham coupling with integral connection contours on the inner shaft and rotor allows for form-fitting, torque-transmitting connections that compensate for dimensional and angular tolerances without the need for complex compensating elements, enabling precise alignment and adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotor is rigidly mounted to the inner shaft using conventional methods (pinning, tolerance chains), then the connection is structurally simple, but manufacturing and assembly inaccuracies cause misalignment between the rotor and stator, leading to contact or complete jamming
Solution Approach 1:
The patent introduces an Oldham coupling as an intermediary mechanism between the rotor and inner shaft. This coupling includes a first connection contour on the inner shaft, a second connection contour on the rotor, and an intermediate element with orthogonal connection contours that mediates the connection. The intermediate element compensates for misalignment caused by manufacturing tolerances, preventing rotor-stator contact and jamming while maintaining a relatively simple overall structure.
2Loss of energy
If tight tolerances are used between rotor and stator to minimize internal leakage, then efficiency is improved, but any manufacturing or assembly error causes the rotor to jam against the stator
Solution Approach 1:
The Oldham coupling acts as a preemptive compensation mechanism that addresses manufacturing and assembly errors before they can cause rotor-stator contact. The intermediate element of the Oldham coupling absorbs dimensional and angular tolerances, providing a cushioning effect that protects the tight-tolerance rotor-stator interface from jamming while maintaining the efficiency benefits of tight tolerances.
3Manufacturing precision
If compensating elements are added to compensate for misalignment, then tolerance compensation is improved, but the device complexity increases
Solution Approach 1:
The Oldham coupling segments the connection function into three distinct parts: the first connection contour on the inner shaft, the second connection contour on the rotor, and the intermediate element with orthogonal contours. This segmentation allows each component to be relatively simple while collectively providing effective tolerance compensation. The orthogonal arrangement of connection contours in the intermediate element enables compensation in multiple directions without requiring complex mechanisms.
Data Source
Figure 1a~3
Figure 4~7b
Figure 8
AI summary
The invention relates to an adjustable camshaft (1) having an inner shaft (2) and an outer shaft (3) arranged coaxially thereto, and having a camshaft adjuster (4), the stator (5) of which is connected to the outer shaft (3) and the rotor (6) of which is screwed to the inner shaft (2). The invention is characterized in that an integral first connection contour (7) is provided at the end of the inner shaft (2) and an integral second connection contour (8), which is complementary to the first connection contour, is provided on the rotor (6), these connection contours directly or indirectly making an interlocking connection between the inner shaft (2) and the rotor (6) possible.