Compact Canned Brushless Motor With Single-Piece Stator
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Solution Overview
Problem
Existing brushless DC motor designs for power tools are too large in diameter to fit within a gripping handle, and those that are smaller often use segmented stators, which are expensive and prone to noise and vibration in high-torque applications.
Innovation Solution
A compact brushless DC motor design with a single-piece stator and small diameter, featuring a motor housing with a stator core, stator windings, and permanent magnets, along with a bearing bridge and compression ring to absorb stack-up tolerances, allowing for high power output while reducing noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a brushless DC motor is designed to output high power, then the power output increases, but the motor diameter becomes greater than or equal to 40 mm making it unsuitable for gripping handles
Solution Approach 1:
The patent changes the magnetic circuit parameters by using a single-piece stator core with optimized tooth geometry and flux distribution. The stator core includes teeth with specific width and height ratios, and the windings are arranged to create concentrated flux paths, enabling high power density in a compact diameter
Solution Approach 2:
The patent employs composite construction combining the single-piece stator core made of electrical steel laminations with permanent magnets in the rotor, creating a hybrid magnetic system that achieves high power output in a compact form factor suitable for gripping handles
2Length of stationary object
If a segmented stator design is used to reduce motor size, then the motor diameter decreases, but the manufacturing cost increases and noise and vibration increase in high torque applications
Solution Approach 1:
The patent merges the stator core into a single-piece construction where the core body and teeth are formed as one integrated component. This eliminates the need for separate segments, reducing manufacturing complexity while maintaining compact dimensions and lowering noise and vibration through improved structural rigidity
3Device complexity
If a single-piece stator design is used, then manufacturing complexity is reduced and noise/vibration decrease, but achieving high power output in small diameter becomes more difficult
Solution Approach 1:
The patent optimizes geometric parameters of the single-piece stator including tooth width, tooth height, slot dimensions, and winding turn counts to maximize flux density and electromagnetic force generation, enabling high power output despite the simplified single-piece construction
Solution Approach 2:
The patent incorporates curved flux paths and optimized magnetic circuit geometry in the single-piece stator design, creating efficient magnetic flux distribution that enhances power density while maintaining the structural simplicity of a single-piece construction
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 design enables a high power output in a small form factor, reducing noise and vibration, and is cost-effective by eliminating the need for segmented stators, making it suitable for power tools like angle grinders and drills.
Implementation Method 1
a rotor rotatably received within the stator and including a rotor shaft extending along a longitudinal axis and permanent magnets
Implementation Method 2
a compression ring disposed within the motor housing between the first insulator and the bearing bridge... configured to absorb stack-up tolerances of the motor
Data Source
AI summary
A motor is provided including a motor housing having a substantially cylindrical body and at least one open end, a stator disposed within the motor housing, and a rotor rotatably received within the stator. The motor further includes a bearing bridge mounted on the open end of the motor housing and including a main body forming a center pocket arranged to support a rotor shaft, an outer ring configured to be fittingly received through the open end of the motor housing, and at least one fastening receptacle formed radially through the outer ring. The motor housing includes a side opening through which a fastener is radially fastened into the fastening receptable to secure the bearing bridge to the motor housing.