Keyless Resolver Rotor Assembly Using Static Magnetic Alignment
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Solution Overview
Problem
The existing methods for assembling resolvers in electric machines rely on key coupling structures, which increase manufacturing costs, reduce sensing accuracy, and introduce errors in angular position sensing due to the complexity of the tolerance chain.
Innovation Solution
A tool and method that utilize a DC voltage applying device to create a static magnetic field, aligning the machine rotor's magnets with the static field, and a pressing device to press-fit the resolver rotor onto the machine shaft without a key coupling structure, ensuring precise angular orientation and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a key coupling structure is used to assemble the resolver rotor to the machine shaft, then the mechanical connection is ensured, but the manufacturing cost increases and the sensing accuracy of angular position deteriorates
Solution Approach 1:
The patent removes the key coupling structure from the assembly, extracting the problematic mechanical connection method that caused tolerance chain issues. The resolver rotor is directly press-fitted to the machine shaft without keys, eliminating the source of angular position errors while maintaining reliable mechanical connection through proper press-fit design.
Solution Approach 2:
The patent replaces the mechanical key coupling system with a direct press-fit connection. By using a pressing device to apply axial force during assembly, the system transitions from a complex mechanical key structure to a simpler direct fit that reduces tolerance links and improves angular position sensing accuracy.
2Reliability
If a key coupling structure is used to assemble the resolver rotor to the machine shaft, then the mechanical connection is ensured, but the manufacturing cost increases
Solution Approach 1:
The patent extracts and removes the key coupling components (keys, keyways) from the assembly process. This elimination reduces the number of parts that need to be manufactured, inventoried, and assembled, thereby reducing manufacturing costs while maintaining reliable mechanical connection through direct press-fit.
Solution Approach 2:
The patent merges the mechanical connection function into a single direct press-fit interface between the resolver rotor and machine shaft, eliminating the separate key coupling components. This consolidation reduces part count, simplifies manufacturing, and lowers overall assembly cost while ensuring reliable mechanical connection.
3Reliability
If a key coupling structure is used, then the resolver rotor can be mechanically connected to the machine shaft, but the number of tolerance links increases
Solution Approach 1:
The patent extracts and eliminates the intermediate key coupling elements that create additional tolerance links in the chain. By establishing a direct press-fit connection between the resolver rotor and machine shaft, the number of interfaces requiring tolerance control is reduced, thereby improving overall manufacturing precision and angular position accuracy.
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 approach eliminates the need for key grooves, reduces the number of tolerance links, enhances sensing accuracy, and maintains high precision in angular position sensing, improving operational stability and reducing noise at high speeds.
Implementation Method 1
applying a DC voltage across at least one phase of windings of three-phase windings of the electric machine to create a static magnetic field by a DC electric current flowing through the at least one phase of windings
Implementation Method 2
the static magnetic field being able to force the machine rotor to rotate to an angular orientation where an N-S direction of magnets of the machine rotor is aligned with an N-S direction of the static magnetic field
Implementation Method 3
a pressing device configured to push the resolver rotor onto the machine shaft in an axial direction
Data Source
Figure 1~3
Figure 4~5
AI summary
Disclosed is an electric machine comprises a resolver which comprises a resolver rotor and a resolver stator, the resolver rotor being assmbled by: applying a DC voltage across at least one phase of windings the electric machine to create a static magnetic field by a DC electric current flowing through the at least one phase of windings of the three-phase windings, the static magnetic field forcing a machine rotor to rotate to an angular orientation where an N-S direction of magnets of the machine rotor is aligned with an N-S direction of the static magnetic field and keeping the machine rotor stably in this angular orientation; and pushing the resolver rotor onto a machine shaft in an axial direction in a state that the machine rotor is kept in the angular orientation by the static magnetic field.