Brushless Power Tool Motor Layout for Compact Assembly
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Solution Overview
Problem
Cordless power tools driven by conventional brushed motors face issues with durability, efficiency, and cost due to brush wear and tear, mechanical commutation failures, and complex assembly processes, while brushless motors are more expensive and challenging to produce, especially in compact designs for hand-held tools.
Innovation Solution
A brushless DC motor design for power tools with a stator and rotor arrangement, electronic commutation using Hall Effect sensors, optimized stator winding configurations, and integrated components to simplify assembly and reduce size, including a compact fan assembly and integrated ring gear mount for improved ergonomics and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brushless DC motor is used instead of brushed motor, then durability and efficiency are improved, but manufacturing cost and assembly complexity increase
Solution Approach 1:
The patent combines the ring gear mount with the motor housing into a single integrated component. This merging eliminates the need for separate alignment and assembly steps between the ring gear and motor, thereby reducing assembly complexity while maintaining the durability benefits of brushless motor technology
Solution Approach 2:
The motor housing serves multiple functions: it provides structural support, acts as a mounting surface for the ring gear, and facilitates thermal management. This multi-functionality reduces the number of separate components needed, simplifying assembly while preserving reliability
2Use of energy by moving object
If brushless DC motor is used instead of brushed motor, then energy efficiency is improved, but manufacturing cost increases
Solution Approach 1:
By integrating the ring gear mount into the motor housing, the patent reduces the total number of parts that need to be manufactured and assembled. This consolidation lowers manufacturing costs through reduced material usage, simplified production processes, and decreased assembly operations, while the brushless motor design maintains high energy efficiency
3Volume of moving object
If compact motor design is implemented, then tool size and weight are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The integration of the ring gear mount with the motor housing eliminates the need for precise alignment between separate components. Since they are manufactured as a single piece, alignment precision requirements are significantly reduced, enabling compact motor design without compromising manufacturing feasibility
4Device complexity
If integrated ring gear mount is used, then assembly process is simplified, but thermal management challenges increase
Solution Approach 1:
The motor housing is designed to serve as both a structural component and a heat dissipation pathway. The integrated design incorporates thermal management features directly into the housing structure, allowing it to perform both mechanical support and thermal regulation functions simultaneously
Solution Approach 2:
The motor housing acts as an intermediary thermal pathway between the motor components and the external environment. By designing the housing with integrated thermal management features, heat from the motor is efficiently conducted and dissipated, managing thermal challenges despite the simplified integrated structure
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 brushless DC motor design enhances durability, efficiency, and cost-effectiveness by minimizing mechanical failures, reducing size, and simplifying assembly, while maintaining high performance and reliability in compact power tool applications.
Implementation Method 1
A set of sense magnets coupled to the PMs in the rotor assembly are sensed by a sensor, such as a Hall Effect sensor, to identify the current position of the rotor assembly
Implementation Method 2
When power is applied to a winding, the resulting current in the winding generates a magnetic field that couples to the rotor. The magnetic field associated with the PM in the rotor assembly attempts to align itself with the stator generated magnetic field resulting in rotational movement of the rotor
Data Source
AI summary
A Brushless Direct-Current (BLDC) motor is provided for a power tool, including a stator comprising a set of coils, a rotor configured to rotate with respect to the stator, power supply lines, terminals secured to the stator outer surface of the stator, and a Hall circuit board. The terminals extend axially on the outer surface of the stator and are radially aligned with one of the stator coils. The terminal block is axially aligned with the same stator coil.