Variable Speed Toggle Trigger for Power Tools

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Solution Overview

Problem

Conventional power tools require separate triggers and levers for reversing motor direction and controlling variable speed, which are costly and complex to manufacture.

Innovation Solution

A variable speed toggle switch with a pivotable trigger that engages a gear segment with a potentiometer to communicate actuation direction and amount to a microprocessor, allowing for single-trigger control of motor direction and speed through an H-bridge or transistors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If separate triggers and reversing levers are used to control motor direction and speed, then the tool can provide independent control of direction and variable speed, but the device complexity and manufacturing cost increase

Engineering Contradiction:

Improveindependent control of direction and speedVSAvoidnumber of separate components

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent combines the reversing lever and variable speed trigger into a single integrated trigger mechanism. The trigger can be actuated in two directions (forward and reverse) while simultaneously providing variable speed control through a rotary encoder, eliminating the need for separate components and reducing overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single trigger serves multiple functions: it controls motor direction through bidirectional actuation and simultaneously controls motor speed through variable actuation amounts. The rotary encoder integrated into the trigger provides both directional detection and speed modulation, making the trigger a universal control element that replaces multiple separate controls.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of operation

If two variable speed triggers are used with a toggle switch, then the user can control direction and speed with a single hand, but the manufacturing cost increases due to requiring two switches

Engineering Contradiction:

Improvesingle-hand control of direction and speedVSAvoidmanufacturing cost

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The patent merges the functions of two separate triggers into one integrated trigger mechanism. The single trigger incorporates both the directional control (through bidirectional actuation) and variable speed control (through rotary encoder detection), eliminating the need for two separate switches and reducing manufacturing complexity and cost.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single trigger acts as a universal control device that performs both directional reversal and variable speed regulation. The rotary encoder integrated into the trigger provides multi-functional feedback, detecting both the direction of actuation and the amount of actuation, thereby replacing the functionality of two separate triggers with one multi-functional component.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If a simple toggle switch is used for direction control, then the device complexity is reduced, but the ability to provide variable speed control is lost

Engineering Contradiction:

Improvesimplicity of switch mechanismVSAvoidvariable speed control capability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The trigger mechanism serves as a universal control device that performs both directional reversal and variable speed regulation. The rotary encoder integrated into the trigger provides multi-functional feedback, detecting both the direction of actuation and the amount of actuation, thereby replacing the functionality of two separate triggers with one multi-functional component.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replaces the traditional mechanical toggle switch with an electronic sensing system using a rotary encoder. This substitution allows the trigger to detect both direction and amount of actuation through electrical signals rather than purely mechanical switches, enabling variable speed control while maintaining a simple physical trigger mechanism.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables users to reverse motor direction and control variable power output with a single trigger mechanism, simplifying design and reducing component costs while maintaining efficient power management.

Implementation Method 1

A trigger can include a gear segment that meshingly engages a gear on a potentiometer

Methodology Applied

Scientific EffectGear meshing: Gear

Data Source

PatentUS8665058B2Variable speed toggle trigger

Publication Date: 2014.03.04 SNAP ON INC

AI summary

A variable speed toggle switch that allows a user to reverse a rotational direction of a motor and supply variable amounts of power to a motor, such as in a power tool, for example, a power drill. A trigger can include a gear segment that meshingly engages a gear on a potentiometer to electrically communicate the actuation direction and actuation amount of the trigger to a microprocessor. The microprocessor can then signal to an H-bridge, or to a series of transistors, the actuation direction and actuation amount of the trigger. A motor or other device can be powered by a power source in an amount corresponding to the actuation amount, and in a direction corresponding to the actuation direction of the trigger.