Electronically Commutated Motor Direct Drive for Hand-Held Tool Ergonomics
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Solution Overview
Problem
Hand-held machine tools, such as angle grinders, often have ergonomically unfavorable designs due to geometric size and mass constraints, making them difficult to handle effectively.
Innovation Solution
The use of an electronically commutated electric motor as a direct drive, eliminating carbon brushes for reduced wear and increased performance, with optimized geometric ratios and a battery-operated option for enhanced flexibility and ergonomics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional motors with carbon brushes are used, then the motor structure is simple and easy to manufacture, but the service life is reduced and performance capability is lower due to wear
Solution Approach 1:
The patent replaces the mechanical carbon brush commutation system with an electronically commutated motor system. The electronic commutation uses sensors and control electronics to switch current in the stator windings, eliminating the mechanical contact and wear associated with carbon brushes, thereby extending service life while maintaining motor functionality
Solution Approach 2:
The patent introduces an electronics system as an intermediary between the power source and the motor windings. This electronics system performs the commutation function that was previously performed mechanically by carbon brushes, using electronic switching devices controlled by sensor feedback to achieve wear-free operation
2Force
If a gear unit is used to transmit power, then the motor can operate at lower speed with higher torque, but the device complexity increases and installation space is reduced
Solution Approach 1:
The patent extracts and removes the gear unit from the drive system, using the electronically commutated motor directly to drive the machining tool. The motor is designed with high torque capability at its operating speed, eliminating the need for mechanical gear transmission and reducing overall device complexity
Solution Approach 2:
The patent changes the operating parameters of the motor to optimize direct drive performance. The electronically commutated motor is controlled to operate at specific speed and torque parameters that are suitable for direct coupling with the machining tool, achieving the required torque without mechanical gear multiplication
3Force
If the motor size is increased to output high torques, then the torque capability is improved, but the ergonomics and handling ability deteriorate
Solution Approach 1:
The patent changes the motor design parameters by using electronic commutation with sensor feedback to precisely control current in the stator windings. This allows the motor to generate high torque at lower speeds with a more compact design, improving the ratio of torque output to motor size and maintaining ergonomic handling
Solution Approach 2:
The patent employs composite construction in the motor design, combining lightweight materials for the rotor and stator components with efficient magnetic materials. This composite approach increases torque density (torque per unit volume) allowing high torque output from a smaller, more ergonomic motor size
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 ergonomic and efficient hand-held machine tool with improved handling and operation, capable of generating high torques without a gear unit, and offering flexible power options through both mains and battery connections.
Implementation Method 1
an electronically commutated electric motor (12) as direct drive
Data Source
AI summary
A hand-held machine tool has an electric-motor drive and a machining tool. The electric-motor drive has an electronically commutated electric motor, and the electric-motor drive is provided to drive the machining tool. The electronically commutated electric motor has an outer diameter, and a ratio of the outer diameter of the electronically commutated electric motor to a diameter of the machining tool is a maximum of 0.42.