Shrink-Fit Torque Motor Cooling Ring for Higher Torque Density
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Solution Overview
Problem
Existing permanent magnet synchronous torque motors fail to achieve sufficient reduction in volume and mass without sacrificing maximum achievable torque for industrial applications.
Innovation Solution
The motor system employs a non-grain-oriented steel armature with compressive stress exceeding 100 MPa, partially saturated electrical windings, and a cooling ring shrink-fitted to the armature, optimizing heat flow and magnetic performance by balancing magnetic saturation in the armature and teeth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the diameter and number of magnetic poles on the rotor are increased to optimize for high torque, then torque density is improved, but the volume and mass of the motor increase
Solution Approach 1:
The patent applies parameter changes by utilizing compressive stress (exceeding 100 MPa) in the armature to enhance magnetic polarization and saturation. This allows the motor to achieve high torque density without increasing volume, as the stress-induced magnetic property changes enable more efficient use of the existing armature space
Solution Approach 2:
The patent employs non-grain-oriented steel as the armature material, which when subjected to compressive stress, exhibits enhanced magnetic properties. This composite approach of stress-treated non-grain-oriented steel allows achieving high torque density without proportionally increasing motor volume
2Power
If compressive stress is applied to the armature to improve magnetic performance, then magnetic polarization is enhanced, but magnetic performance degradation occurs due to stress
Solution Approach 1:
The patent converts the harmful effect of compressive stress (which typically degrades magnetic performance) into a beneficial effect. By applying controlled compressive stress exceeding 100 MPa to non-grain-oriented steel, the patent achieves enhanced magnetic polarization and saturation, turning the normally detrimental stress into a performance-enhancing factor
Solution Approach 2:
The patent changes the magnetic parameters of the armature material by applying compressive stress. This stress-induced parameter change increases magnetic polarization and enables deeper saturation, improving overall magnetic performance rather than degrading it
3Temperature
If the armature is shrink-fitted to reduce thermal contact resistance, then heat flow is optimized, but compressive stress is introduced that may affect magnetic properties
Solution Approach 1:
The patent converts the harmful thermal contact resistance into a beneficial compressive stress state. The shrink-fit process, which normally just improves thermal contact, is used to induce compressive stress exceeding 100 MPa in the armature, which then enhances magnetic polarization and performance
Solution Approach 2:
The shrink-fit process creates a phase change in the stress state of the armature, transitioning from a stress-free or tensile state to a high compressive stress state. This stress phase transition enables the non-grain-oriented steel to exhibit enhanced magnetic properties
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 configuration allows for a compact motor design with enhanced torque density by compensating for magnetic performance degradation through stress-related improvements, maintaining high magnetic saturation and efficient cooling.
Implementation Method 1
Shrink-fitting results in a continuous compressive pressure between armature and cooling ring, reducing the thermal contact resistance and optimizing heat flow
Implementation Method 2
the coils in the stator are energized so as to produce a rotating magnetic field, which is matched to the field of the rotor in frequency
Implementation Method 3
A permanent magnet synchronous motor uses permanent magnets to produce the constant rotor field
Implementation Method 4
the electrical power supply is configured to provide electrical power and/or current to the plurality of windings such that the teeth and the armature are at least partially saturated
Data Source
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Figure 2B
AI summary
The present invention relates to a permanent magnet synchronous torque motor. The present invention further relates to a motor system comprising such a motor. In addition, the present invention relates to a method for manufacturing the motor. The motor comprises a stator having an armature and teeth extending therefrom. The motor further comprises a rotor, and a cooling ring arranged around the stator. According to the invention, the cooling ring is shrink-fitted around the armature.