Motor Fan Guide and Labyrinth Cooling for Dust-Prone Electric Tools
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Solution Overview
Problem
Conventional electric tools, such as disc grinders, face inadequate cooling performance for the inner stator, particularly the coil, due to insufficient air volume and dust intrusion issues, which can lead to overheating and adhesion of metal powder on the rotor core.
Innovation Solution
The design incorporates a fan guide with a labyrinth structure and nonmagnetic insulators to concentrate cooling air within the stator, along with a filter attachment mechanism that prevents dust entry and facilitates easy removal, ensuring efficient cooling without increasing tool size or manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the air volume of the cooling air is increased to prevent dust adhesion on the rotor, then the cooling performance improves, but the size of the cooling fan may need to be increased which is limited by the motor housing size
Solution Approach 1:
The invention changes the parameters of the cooling air by increasing its velocity through optimized flow paths and guide structures, rather than simply increasing the fan size. The cooling air guide portions are designed to direct air flow efficiently, creating high-velocity streams that can remove dust from the rotor surface without requiring a larger fan.
Solution Approach 2:
The invention utilizes the axial dimension by directing cooling air from the axial direction toward the rotor surface. The cooling air guide portions extend in the axial direction and direct air flow to sweep across the rotor surface, effectively removing dust particles without requiring increased radial fan size.
2Object-affected harmful factors
If a filter is provided at the intake port to suppress dust intrusion, then dust adhesion is reduced, but a large amount of dust may adhere to the filter in a short time requiring frequent maintenance
Solution Approach 1:
The invention employs the cooling air flow to perform self-cleaning of the filter. The cooling air, after passing through or near the filter, is directed to flow across the rotor surface and out through the exhaust port. This continuous air flow helps prevent excessive dust accumulation on the filter by sweeping particles away, reducing the frequency of filter maintenance.
Solution Approach 2:
The invention converts the potentially harmful dust particles into a beneficial effect by using them as indicators of effective cooling air flow. The dust particles that would normally clog the filter are instead used to demonstrate that the cooling air is flowing through the system and performing its dust-removal function on the rotor surface.
3Device complexity
If the cooling fan rotates in synchronization with the motor, then the cooling system is simple, but the rotational speed of the cooling fan cannot be increased independently to improve cooling performance
Solution Approach 1:
The invention introduces dynamic control capability by allowing the cooling fan to be driven independently from the motor. The cooling fan can be driven by a separate drive circuit that receives control signals from the control unit, enabling the rotational speed of the cooling fan to be adjusted independently based on cooling requirements, dust conditions, or operational modes.
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 enhances cooling performance for the motor's inner components, preventing dust adhesion and maintaining efficient operation, even in environments with metal powder, while maintaining tool size and cost.
Implementation Method 1
a cooling fan that can be attached to a rotation shaft of the motor is provided, and a heat generating portion is cooled by sucking outside air and sending cooling air to the motor. The cooling air is configured to flow in an axial direction on an outer peripheral side of a stator and in a space between a rotor and the stator.
Data Source
AI summary
An electric tool is provided which enables preventing adherence to a rotor core of dust, such as iron powder, that has entered a motor. The electric tool includes a cylindrical motor housing 10 accommodating and supporting the motor, and a cooling fan attached to a rotation shaft of the motor, and cools the motor by flowing air generated by the cooling fan toward the back or front of the motor housing 10, wherein a fan guide 50 guiding cooling air is provided in front of an insulator 35 of a stator 30 of the motor. The fan guide 50 includes a first cylindrical part 51 which covers a rotation space of the cooling fan, a guide surface 53, and a second cylinder 55 which extends backward from the guide surface 53, wherein a labyrinth space 39 is formed by the insulator 35 and the second cylinder 55. By providing the labyrinth space 39, it is possible to block the flow of cooling air from the outer peripheral side of the stator 30 to an opening 53a.