Compact Power Tool Motor Wiring for High Current Draw
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power tools face a trade-off between compact size and the ability to draw large currents, with light load motors being too small and heavy load motors being too large, limiting their applicability.
Innovation Solution
A compact power tool design utilizing a motor with a stator and rotor, where coils are wound through insulators, and a short circuiting means connects diagonally-positioned pairs of winding wires, allowing a single continuous wire to draw large currents while maintaining a small size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a light load motor is used to reduce size, then the power tool becomes compact, but the motor cannot draw large currents limiting its applicability
Solution Approach 1:
The patent changes the electrical connection configuration from series to parallel by using short circuiting means to connect diagonally opposite coils. This parameter change in wiring topology allows the motor to draw larger currents while maintaining a compact size, resolving the contradiction between small motor size and current drawing capability.
2Reliability
If a heavy load motor is used to draw large current, then the current handling capability is sufficient, but the motor becomes larger and unsuitable for compact power tools
Solution Approach 1:
The patent modifies the electrical parameters by implementing parallel connection of coils through short circuiting means. This allows a compact motor structure to achieve heavy load current handling capability, eliminating the need for large-sized motors while maintaining sufficient current drawing capability.
3Reliability
If lead wires are directly connected to fusing terminals for heavy load, then robust current handling is achieved, but the structure becomes more complex and less space-saving
Solution Approach 1:
The patent merges the connection structure by integrating short circuiting means that simultaneously achieve both current handling and structural compactness. The diagonally opposite coil connection method combines multiple functions into a unified structure, reducing overall device complexity while maintaining robust current handling.
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 compact power tool capable of drawing large currents, achieving a balance between size and performance by using a parallel-wound coil configuration and a short circuiting element that maintains a compact form factor.
Implementation Method 1
A plurality of coils (e.g., at least six) are wound on the stator such that the coils are wound through respective insulators located at the front and rear in an axial direction of the stator
Data Source
AI summary
A power tool includes a housing formed of two half-housings and an end cap. A stator is mounted in the housing, and a rotor including a rotor core and a permanent magnet is mounted in the stator core. A rotary shaft having an axis of rotation extending in a front-rear direction supports the rotor core. Insulators are mounted at front and rear axial ends of the stator core, a planetary gear is mounted forward of the rotor core and a handle extends from the housing. The front insulator includes two recesses, and a first portion of each recess opens radially and a second portion of each recess opens axially rearward. Portions of the stator core cover the recesses, and projections extend from the housing and respectively mate with the recesses.