Electric Tool Speed Regulation via Segmented Copper Foil

Solution Overview

Problem

Existing rotation speed regulation systems in electric tool switches produce non-uniform speed signals, leading to fluctuations in motor speed due to an unreasonable design.

Innovation Solution

A rotation speed regulation system featuring a resistance regulating copper foil with short-circuit gold fingers, full-resistance, and zero-resistance foils, connected in series with a resistor, and a reed that slides between these foils, optimizing the inclination angle and contact strip length to ensure uniform speed signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a conventional speed regulating mechanism is used with a speed regulating switch and reed sliding on copper foil, then the motor speed can be adjusted, but the speed regulating signal curve is non-uniform causing obvious fluctuations in motor speed

Engineering Contradiction:

Improvemotor speedVSAvoidspeed signal uniformity

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The copper foil is divided into multiple segments including full-resistance foil, zero-resistance foil, and short-circuit gold fingers arranged in sequence. This segmentation allows different resistance values to be applied at different positions, creating a uniform speed regulating signal curve that eliminates motor speed fluctuations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the copper foil structure have different electrical properties: full-resistance foil provides maximum resistance, zero-resistance foil provides minimum resistance, and short-circuit gold fingers provide intermediate resistance values. This local differentiation of electrical properties enables precise control of the speed regulating signal to achieve uniform motor speed adjustment.

Inventive Principle:

Principle #3Local quality

2Stability of the object's composition

If the short-circuit gold fingers are arranged with specific inclination angle and spacing, then the speed regulating signal becomes uniform, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvespeed signal uniformityVSAvoidgold finger arrangement precision

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

Specific parameters are optimized to achieve the desired performance: the inclination angle of short-circuit gold fingers is set to 107°-110° relative to the sliding direction, the width is 0.27mm, and the spacing between adjacent fingers is 0.2mm. These parameter optimizations create a uniform speed regulating signal while providing clear manufacturing specifications.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If the contact strip length is optimized within a specific range, then the speed regulation becomes uniform, but the device complexity increases

Engineering Contradiction:

Improvespeed signal uniformityVSAvoidfoil structure complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The copper foil is divided into multiple segments including full-resistance foil, zero-resistance foil, and short-circuit gold fingers arranged in sequence. This segmentation allows different resistance values to be applied at different positions, creating a uniform speed regulating signal curve that eliminates motor speed fluctuations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the copper foil structure have different electrical properties: full-resistance foil provides maximum resistance, zero-resistance foil provides minimum resistance, and short-circuit gold fingers provide intermediate resistance values. This local differentiation of electrical properties enables precise control of the speed regulating signal to achieve uniform motor speed adjustment.

Inventive Principle:

Principle #3Local quality

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 design results in a uniform speed signal output, reducing or eliminating motor speed fluctuations by adjusting the duty cycle of the pulse signal in a controlled manner.

Implementation Method 1

The resistance regulating copper foil includes a first foil and a second foil separated from each other... The short-circuit gold fingers, the zero-resistance foil and the full-resistance foil are sequentially connected in series through a resistor... One end of the resistance regulating reed contacting the first foil is a constant contact end, and the other end of the resistance regulating reed contacting the second foil is a resistance regulating contact end

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentUS11258382B1Rotation speed regulation system for electric tool switch

Publication Date: 2022.02.22 SUZHOU HUAZHIJIE TELECOM

AI summary

A rotation speed regulation system for an electric tool switch includes a controller, a resistance regulating copper foil electrically connected to the controller, and a resistance regulating reed matched with the resistance regulating copper foil. The resistance regulating copper foil includes a first foil and a second foil separated from each other. The first foil is an intact long strip foil. The second foil includes a plurality of short-circuit gold fingers arranged at equal intervals in the middle part and a full-resistance foil and a zero-resistance foil at both ends. The width of the short-circuit gold finger is 0.27 mm, and the distance between two adjacent short-circuit gold fingers is 0.2 mm. An inclination angle α is formed between the short-circuit gold finger and the sliding direction of the resistance regulating contact end, α is 107°-110° and the length L of the contact strip is 2.3-2.9 mm.