Brushless Motor Electric Tool Switch Overheating Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric tools using universal motors with commutators are inefficient, leading to increased length and weight, making them unsuitable for long-time operation, and the tumbler switch's placement on the current path causes overheating and contact point melting during overloads.
Innovation Solution
The electric tool employs a high-efficiency brushless motor without a commutator and utilizes a tumbler switch for control, integrating a control circuit and inverter circuit to manage the brushless motor's operation, ensuring efficient and safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a universal motor with commutator is used as driving source, then the motor can operate on commercial alternating current, but the overall length of the electric tool is lengthened and weight becomes heavy
Solution Approach 1:
The patent extracts and removes the commutator and brush assembly from the motor structure, replacing them with a brushless DC motor design. This extraction eliminates the complex mechanical commutation system while maintaining the motor's core functionality, directly reducing the overall length and structural complexity of the electric tool.
Solution Approach 2:
The patent replaces the mechanical commutator-brush system with an electronic control system. The brushless DC motor uses electronic commutation through a control circuit instead of mechanical contact, substituting a complex mechanical system with a more compact electronic system that reduces overall tool length and complexity.
2Weight of moving object
If a universal motor with commutator is used as driving source, then the motor can operate on commercial alternating current, but the weight of the electric tool becomes heavy
Solution Approach 1:
The patent extracts and removes the heavy commutator and brush assembly from the motor structure, replacing them with a brushless DC motor design. This extraction eliminates the complex mechanical commutation system while maintaining the motor's core functionality, directly reducing the overall length and structural complexity of the electric tool.
Solution Approach 2:
The patent replaces the mechanical commutator-brush system with an electronic control system. The brushless DC motor uses electronic commutation through a control circuit instead of mechanical contact, substituting a complex mechanical system with a more compact electronic system that reduces overall tool length and complexity.
3Reliability
If the tumbler switch is arranged on the discharge path (current path), then the switch can control the motor operation, but over-current flows during overload causing contact point melting
Solution Approach 1:
The patent introduces a control circuit as an intermediary between the tumbler switch and the motor. The control circuit receives the switch signal and manages motor operation through electronic control, preventing direct over-current flow through the switch contact points. This intermediary protects the switch from harmful over-current effects while maintaining reliable control functionality.
4Use of energy by moving object
If a universal motor is used, then the motor provides sufficient power, but the efficiency is low making it unsuitable for long-time operation
Solution Approach 1:
The patent replaces the universal motor with a brushless DC motor that uses electronic commutation instead of mechanical brushes and commutators. This substitution eliminates energy losses associated with mechanical contact and friction, significantly improving motor efficiency and enabling sustained long-time operation without excessive heat generation or energy consumption.
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 results in a more compact, lightweight tool capable of long-time operation with improved workability and operability, preventing overheating and allowing for soft start mechanisms to prevent overcurrents.
Implementation Method 1
a brushless motor 40 having an output shaft 41, a rotor 42 having a plurality of permanent magnets, a stator 44 having a plurality of stator windings 43
Implementation Method 2
a rotor 42 having a plurality of permanent magnets, a stator 44 having a plurality of stator windings 43
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electric tool includes a brushless motor and an output part, which is driven by the brushless motor and to which a tip tool is mounted, and a tumbler switch. The tumbler switch applies, to the control unit, a stop signal for stopping the brushless motor at a neutral position, a forward rotation signal for forward rotating the brushless motor by an operation in a first direction, and a reverse rotation signal for reversely rotating the brushless motor by an operation in a second direction.