Stator Connection Circuit Board With Integrated Rotor Sensing
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Solution Overview
Problem
Conventional brushless DC (BLDC) motors in power tools face challenges in maximizing power density due to inefficient motor cooling techniques, which result in wasted space and reduced performance.
Innovation Solution
A BLDC motor design featuring an external cooling system with heat sinks that dissipate heat to the outside environment, eliminating the need for large airflow paths within the stator slots, allowing for increased slot fill and improved thermal conductivity, thereby enhancing power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling techniques with airflow paths through stator slots are used, then motor cooling is achieved, but slot fill is limited to 50% or less and power density is reduced
Solution Approach 1:
The patent extracts the cooling function from the stator slot interior to an external heat sink structure. The heat sink is coupled to the stator core outer surface, removing the need for internal airflow paths through the slots. This allows stator slots to be completely filled with copper windings (100% slot fill) while cooling is handled externally by the heat sink with fins and airflow passages on the stator core exterior.
Solution Approach 2:
The cooling approach transitions from a two-dimensional internal slot cooling to a three-dimensional external heat sink structure. The heat sink extends radially outward from the stator core with fins providing increased surface area for heat dissipation in the radial direction, while cooling airflow passes through external passages rather than through the slot space.
2Temperature
If large airflow paths are provided within stator slots for cooling, then motor cooling is achieved, but motor volume increases and power density decreases
Solution Approach 1:
The cooling function is extracted from the stator slot interior to an external heat sink structure. The heat sink is coupled to the stator core outer surface, removing the need for internal airflow paths through the slots. This allows stator slots to be completely filled with copper windings (100% slot fill) while cooling is handled externally by the heat sink with fins and airflow passages on the stator core exterior.
Solution Approach 2:
The heat sink structure acts as a thin-walled external cooling shell that couples to the stator core outer surface. The heat sink includes a body with internal airflow passages and external fins, providing a flexible cooling architecture that dissipates heat without requiring internal slot space, thereby reducing overall motor volume while maintaining effective cooling.
3Power
If slot fill is increased to improve power density, then motor power output increases, but motor cooling becomes insufficient
Solution Approach 1:
The cooling function is extracted from the stator slot interior to an external heat sink structure. The heat sink is coupled to the stator core outer surface, removing the need for internal airflow paths through the slots. This allows stator slots to be completely filled with copper windings (100% slot fill) while cooling is handled externally by the heat sink with fins and airflow passages on the stator core exterior.
Solution Approach 2:
The heat sink structure employs composite construction with a heat sink body made of thermally conductive material coupled to the stator core, featuring internal airflow passages and external fins. This composite structure provides both mechanical support and thermal management functions, enabling high slot fill ratios for increased power output while maintaining effective cooling through the external heat dissipation pathway.
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 significantly increases volumetric power density by optimizing slot fill and thermal management, leading to more compact and high-performance power tools.
Implementation Method 1
external cooling system with heat sinks that dissipate heat to the outside environment
Implementation Method 2
heat sinks that dissipate heat to the outside environment
Implementation Method 3
at least one magnetic sensor mounted on a surface of the circuit board around the central through-hole configured to magnetically interface with the rotor
Implementation Method 4
stator windings wound around the stator teeth... arranged to magnetically interface with the stator windings
Data Source
AI summary
A motor assembly is provided including a stator and a rotor. The stator includes a stator main body defining a longitudinal axis, stator teeth projecting radially from the stator main body, stator windings wound around the stator teeth, and two winding terminals provided for each stator tooth extending away from the stator main body substantially parallel to the longitudinal axis. A circuit board is oriented along a radial plane adjacent the stator. The circuit board includes a central through-hole through which a rotor shaft extends, at least one magnetic sensor mounted on a surface of the circuit board around the central through-hole configured to magnetically interface with the rotor, peripheral openings arranged to receive the winding terminals of the stator, and conductive routings extending from the peripheral openings to connect the stator windings in a series or a parallel configuration and/or a wye or a delta configuration.