Stator Wound-Tooth Temperature Sensing for Faster Motor Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power tools with electric motors face issues in timely temperature protection due to long thermal conduction paths and external temperature interference affecting NTC thermistors, leading to reduced performance and potential machine failure.
Innovation Solution
The temperature sensor is placed directly on the wound tooth of the stator, eliminating the thermal conduction path and external interference, allowing for precise temperature monitoring and protection of the electric motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the NTC thermistor is added to the outer surface of the iron core for temperature protection, then the electric motor can be protected from excessive temperature rise, but the thermal conduction path becomes excessively long and the protection is not timely
Solution Approach 1:
The patent introduces a temperature sensor as an intermediary element positioned between the heating winding and the external environment. This sensor directly contacts the winding through the insulating end cover, creating an efficient thermal conduction path that rapidly transmits temperature information from the heat source to the protection system, thereby resolving the timing delay in motor protection.
2Measurement precision
If the NTC thermistor is placed on the outer surface of the iron core, then temperature monitoring is implemented, but the thermistor is greatly affected by external temperature where hot air is blown to the thermistor and the machine is prone to enter temperature protection state in advance
Solution Approach 1:
The patent extracts the temperature sensor from the external environment and positions it internally within the motor structure, specifically on the insulating end cover adjacent to the heating winding. This extraction removes the sensor from the harmful external temperature field (hot air flow), eliminating false temperature readings and premature protection states while maintaining accurate monitoring of actual motor temperature.
3Reliability
If additional fixing structures are added to secure the temperature sensor, then the sensor is firmly fixed, but the device complexity and parts quantity increase
Solution Approach 1:
The patent merges the temperature sensor fixation function with the existing insulating end cover structure. The sensor is directly installed on the insulating end cover, which serves both as an electrical insulator and as a mounting substrate for the sensor. This integration eliminates the need for separate fixing structures, reducing parts quantity and device complexity while ensuring reliable sensor positioning.
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 enables timely and accurate temperature sensing, enhancing motor protection while reducing parts and costs by eliminating the need for additional fixing structures.
Implementation Method 1
The temperature sensor is placed on a first tooth surface of any wound tooth... the thermal conduction path of a heating winding is excessively long
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A power tool includes an electric motor, a transmission mechanism, and a temperature sensor. The electric motor includes a stator and a rotor. The stator includes a stator lamination, an insulating end cover, and coils. The insulating end cover includes an end cover body and multiple wound teeth. The temperature sensor is placed on a first tooth surface of any wound tooth. The first tooth surface is a plane substantially perpendicular to a rotating shaft of the rotor. The temperature sensor is disposed on the wound tooth and the thermal conduction path between a coil and the temperature sensor is removed so that the temperature sensor is in direct contact with the coil. Thus, a temperature change of the electric motor can be sensed in time, and the electric motor is protected in time. In addition, the influence of an external environment on the temperature sensor is eliminated, and the electric motor is accurately protected. In addition, the temperature sensor is directly disposed on the wound tooth in advance, then the coil is wound on the wound tooth to wrap and fix the temperature sensor, and an additional temperature sensor fixing structure is not required. Thus, parts are reduced, and the cost is low.