Power Tool Handle Cord Routing Reduces Line Resistance
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Solution Overview
Problem
Conventional portable circular saws experience increased line resistance and voltage drop due to longer power-supply cord lengths, which are connected to the motor via a trigger switch, leading to heat generation and other adverse effects.
Innovation Solution
The power-supply cords are routed through the proximal end portion of the handle, avoiding the grip portion, and a motor control device is positioned to distribute the cords within the handle, reducing the overall cord length and line resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If power-supply cords are connected to the motor via the trigger switch in the grip portion, then the trigger switch can control the motor activation, but the cord length increases leading to increased line resistance and voltage drop
Solution Approach 1:
The patent divides the handle into functional segments: the grip portion containing only the trigger switch, and a separate proximal end portion containing the power-supply cord insertion portion. This segmentation allows the power-supply cords to be routed through the proximal end portion rather than passing through the grip portion, thereby reducing cord length and line resistance while preserving trigger switch control functionality.
2Ease of operation
If power-supply cords are routed through the grip portion to connect to the motor, then the trigger switch can control power flow, but the cord length increases causing heat generation
Solution Approach 1:
The patent separates the power-supply cord routing path from the trigger switch location by positioning the cord insertion portion in the proximal end portion of the handle rather than in the grip portion. This segmentation reduces cord length, thereby minimizing I²R losses and heat generation while maintaining the trigger switch's ability to control power flow to the motor.
3Ease of operation
If the cord length of power-supply cords is increased to allow routing through the trigger switch, then the trigger switch can be easily accessed, but line resistance increases and performance deteriorates
Solution Approach 1:
The patent resolves the contradiction between trigger switch accessibility and electrical performance by segmenting the handle structure: the grip portion remains accessible for trigger operation, while the proximal end portion provides a dedicated insertion point for power-supply cords. This allows short cord routing that minimizes line resistance and maintains reliable electrical performance while preserving ease of operation.
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 reduces the cord length of the power-supply cords, minimizing line resistance and preventing voltage drops and heat generation, thereby enhancing the performance of the electrical power tool.
Implementation Method 1
Power-supply cords of the motor are introduced into the tool housing through a power-supply cord insertion portion that is positioned in a middle portion of the handle
Data Source
AI summary
An electrical power tool (10) may include a tool housing (30) that is formed by connecting an outer circumferential surface of a motor housing (33) containing a motor (22) therein and a proximal end portion (35y) of a handle. The handle (35) has a grip portion (35g) provided to a portion close to a distal end portion (35s) thereof and having a trigger switch (37) to activate the motor (22). Power-supply cords (40p,40n,43u,43v,43w) of the motor are introduced into the tool housing (30) through a power-supply cord insertion portion (38) that is positioned in a portion of a proximal end portion (35y) of the handle. A distribution path of the power-supply cords (40p,40n,43u,43v,43w) is positioned in a portion other than the grip portion (35g) of the handle (35).