Feather Key Interface for Electric Machine Shaft Connection
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Solution Overview
Problem
Existing electrical machines face challenges in providing a simple, reliable, and durable mechanical interface for connecting add-on parts, particularly under operational forces such as shear and centrifugal forces, which can lead to detachment issues.
Innovation Solution
A feather key interface is designed with a shaft-side fitting groove and an attachment-side contour, featuring a press-fit mechanism and a spring body that engages with the add-on part, providing both positive and frictional connections to secure the add-on part to the machine shaft, preventing relative rotational movement and ensuring stability against centrifugal forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional keyway interface is used to connect the attachment to the machine shaft, then the connection can withstand shear forces, but the attachment may still detach under centrifugal forces during operation
Solution Approach 1:
The keyway is segmented into two distinct components: a shaft-side keyway with limited circumferential extent (less than one-quarter of the shaft circumference) and an attachment-side contour with corresponding engagement features. This segmentation allows each component to be optimized independently - the shaft-side keyway provides shear force resistance while the attachment-side contour provides centrifugal force resistance through its engagement geometry.
Solution Approach 2:
The solution transitions from a traditional single-plane keyway to a three-dimensional interface system. The shaft-side keyway is limited in circumferential extent but extends axially, while the attachment-side contour incorporates radial, axial, and circumferential engagement features. This dimensional transformation enables the interface to resist both shear forces (along the shaft axis) and centrifugal forces (radially outward) simultaneously.
2Strength
If the keyway extends over the entire shaft circumference or a substantial part thereof, then the connection appears more robust, but the manufacturing complexity and material removal increase
Solution Approach 1:
The invention extracts only the necessary portion of the traditional circumferential keyway, limiting it to less than one-quarter of the shaft circumference. This extraction maintains sufficient connection strength by concentrating the keyway at the critical interface location where the attachment connects to the shaft, while significantly reducing the amount of material removal and manufacturing complexity associated with full-circumference keyways.
Solution Approach 2:
Instead of distributing the keyway uniformly around the shaft circumference, the invention concentrates the keyway at a specific local position where it is most effective for the attachment connection. This local concentration of the keyway provides sufficient mechanical strength at the critical interface while minimizing the overall impact on the shaft structure and reducing manufacturing complexity.
3Ease of operation
If a simple mechanical interface is used for attaching components to the shaft, then the ease of assembly improves, but the interface may not provide sufficient reliability under operational forces
Solution Approach 1:
The invention introduces an intermediary key element that mediates between the shaft-side keyway and the attachment-side contour. This key serves as a mechanical intermediary that translates the simple insertion action into a reliable multi-force-resistant connection. The key engages with both the shaft-side keyway and the attachment-side contour, providing positive mechanical engagement that ensures both assembly ease and operational reliability.
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
The feather key interface establishes a reliable, shaft-fixed connection that withstands operational forces, preventing detachment and ensuring accurate torque support, suitable for applications like resolver torque support in electrical machines.
Implementation Method 1
a spring element (10b) attached to it, preferably integrally formed... the spring element of the key engages in the connection contour on the attachment side
Implementation Method 2
The shaft-side interface element, hereinafter referred to as a key or keyway element, sits in a shaft-side keyway, in particular in the manner of an interference fit
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
The invention relates to an interface (8) between a shaft (5) and an attachment (9), for example an angle sensor, an encoder, a resolver, a gear, or the like, with a shaft-side key (10) and an attachment-side connection contour (9b), in particular for a positive and/or force-fit connection of the attachment (9) to the shaft (5). In particular, the invention relates to an electric machine with a machine housing (2) for receiving a stator (3) and a rotor (4) mounted on a machine shaft (5), and with an attachment (9) connected to the machine shaft (5) via a mechanical interface (8), in particular by positive and/or force-fit connection.