Segmented Mounting Shaft for Electric Motor Encoder Alignment
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Solution Overview
Problem
Existing add-on shafts for electric motors often have suboptimal strength and concentricity issues in their connection to the motor shaft, which can lead to misalignment and reduced accuracy in speed or position detection by rotary encoders.
Innovation Solution
The add-on shaft is designed with multiple cylindrical sections of varying diameters, featuring a press fit for secure alignment and an adhesive application area to enhance bonding, ensuring high concentricity and strength through precise tolerance fits and surface roughness for improved adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple cylindrical add-on shaft is used for extending the motor shaft, then the device complexity is reduced, but the concentricity and alignment precision deteriorate
Solution Approach 1:
The add-on shaft is divided into multiple cylindrical sections (first, second, third, fourth sections) with different diameters along its length. This segmentation allows different portions of the shaft to serve different functions: some sections provide press-fit connections for alignment, while others provide adhesive bonding surfaces, thereby achieving high concentricity without requiring an overly complex single-piece design
Solution Approach 2:
Different sections of the add-on shaft have different diameters tailored to their specific functions. The second and fourth sections have larger diameters for press-fit alignment, while the third section has a smaller diameter optimized for adhesive application. This local differentiation of geometric properties enables precise concentricity control while maintaining overall structural simplicity
2Strength
If a press fit connection is used to secure the add-on shaft, then the strength of connection is improved, but the adhesive application becomes difficult
Solution Approach 1:
The shaft is segmented into distinct functional zones: the second section with larger diameter provides the press-fit connection for strength, while the third section with smaller diameter creates a dedicated adhesive application area. This segmentation ensures that the press-fit and adhesive bonding processes do not interfere with each other, allowing both connection methods to work effectively together
Solution Approach 2:
The third section is specifically designed with a smaller diameter to create optimal conditions for adhesive application and retention. The reduced diameter in this local area prevents adhesive from being wiped off during insertion while the adjacent larger-diameter sections maintain the press-fit connection, thereby solving the conflict between connection strength and adhesive applicability
3Length of moving object
If the add-on shaft is inserted into the blind hole, then the motor shaft extension is achieved, but the adhesive may be wiped off during insertion
Solution Approach 1:
By dividing the shaft into sections with varying diameters, the invention creates a specific geometry where the third section's smaller diameter acts as an adhesive retention zone. During insertion, the larger-diameter second and fourth sections lead the way while the smaller third section maintains the adhesive in place, ensuring the adhesive bond is not compromised by the insertion process
Solution Approach 2:
The local reduction in diameter at the third section creates a geometric feature that naturally retains adhesive during the insertion process. This localized geometric modification ensures that adhesive applied to the shaft surface remains in position on the third section even as the shaft is inserted into the blind hole, thereby preserving bond strength while achieving the required shaft extension
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design significantly increases the strength and concentricity of the connection between the motor shaft and the add-on shaft, resulting in more accurate position or speed measurements from rotary encoders and a resilient drive for functionally safe encoder attachments.
Implementation Method 1
fixing it there, in particular by gluing it
Implementation Method 2
there is at least a slight press fit with the blind hole of the motor shaft
Data Source
Figure 1~2
Figure 3~6
Figure 7
AI summary
The invention is primarily a mounting shaft (16) for an electric motor (12) with a pin (18) provided for insertion into a blind hole (14) in a motor shaft (10) of the electric motor (12), wherein the pin (18) has sections (30, 32, 34, 36) with different diameters which ensure that the mounting shaft (16) is aligned coaxially with the motor shaft (10) and that adhesive applied to the pin (18) is not wiped off during joining and a defined adhesive gap is maintained, and furthermore also an electric motor (12) with such a mounting shaft (16), the use of such a mounting shaft (16) as a drive shaft of a rotary encoder (24) and a method for connecting such a mounting shaft (16) to a motor shaft (10).