Electric Machine Sensor Fixation Using Paraffin Phase Transition
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Solution Overview
Problem
Electrical machines face issues with heat dissipation in stator windings leading to overheating, efficiency reduction, and potential electrical breakdowns, while existing temperature sensors suffer from inaccurate measurements due to mechanical instability and thermal expansion issues, resulting in reduced service life.
Innovation Solution
An electrical machine design that incorporates a sensor and connection lines within the stator or rotor, utilizing a filling with a matrix and expanded hollow bodies filled with an expansion agent to compensate for thermal expansion, ensuring the sensor's secure fixation and accurate temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are placed in the stator or rotor for temperature monitoring, then temperature measurement capability is improved, but mechanical stability and measurement accuracy deteriorate due to thermal expansion and mechanical influences
Solution Approach 1:
The patent utilizes the phase transition of paraffin wax from solid to liquid state at around 50-60°C. The paraffin is housed in a reservoir within the sensor assembly, and when thermal expansion occurs, the paraffin melts and absorbs the expansion forces, preventing damage to the sensor and maintaining measurement accuracy while compensating for thermal effects
Solution Approach 2:
The patent implements beforehand cushioning by incorporating a shock-absorbing element (paraffin wax) that anticipates and compensates for thermal expansion forces before they can damage the sensor. The paraffin is pre-positioned in the reservoir to absorb expansion forces, protecting the sensor from mechanical damage and maintaining measurement reliability
2Strength
If PTFE sleeves are used to protect sensors and connection lines, then mechanical protection is improved, but thermal expansion compensation deteriorates due to PTFE's high coefficient of thermal expansion and creep behavior
Solution Approach 1:
The patent replaces PTFE sleeves with a paraffin-based phase transition mechanism. The paraffin wax melts at 50-60°C, absorbing thermal expansion forces through phase change rather than creep. This provides mechanical protection while simultaneously compensating for thermal expansion, eliminating the contradiction between protection and thermal stability
Solution Approach 2:
The patent changes the material parameter from PTFE (high creep, high thermal expansion) to paraffin wax (phase transition at 50-60°C). This parameter change allows the material to absorb thermal expansion through melting rather than permanent deformation, maintaining both mechanical protection and thermal stability
3Reliability
If sensor connection lines are enclosed in PTFE sleeves, then electrical insulation is improved, but sensor fixation and thermal response deteriorate due to loosening from thermal expansion
Solution Approach 1:
The patent uses paraffin wax phase transition (solid to liquid at 50-60°C) to maintain firm contact between connection lines and the sensor assembly. As the paraffin melts, it flows around the connection lines, maintaining electrical insulation while allowing thermal expansion without loosening, thus preserving both insulation and thermal response 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
The solution effectively addresses overheating and mechanical instability issues, enhancing the reliability and accuracy of temperature measurements, thereby increasing the failure safety and service life of electrical machines.
Implementation Method 1
heating the hollow bodies to a temperature which is higher than an expansion start temperature of the hollow bodies
Implementation Method 2
In order to monitor the temperature of the end windings of stators, sensors, usually protected by a PTFE coating (polytetrafluoroethylene), are usually placed in the winding
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to an electric machine (10) comprising a stator (12), a rotor (40), a sensor (20), and connecting leads (22) connected to the sensor (20), wherein the sensor (20) and at least a portion of the connecting leads (22) are arranged within the stator (12) or rotor (40). The electric machine (10) comprises a filling (30), wherein the filling (30) has a matrix (32) and hollow bodies (34) distributed within the matrix (32) and filled with an expanding agent (38), and at least a portion of the connecting leads (22) is at least partially enclosed by the filling (30). The invention also relates to a method for manufacturing an electric machine.