Rotary Input Control for Power Tool Speed Adjustment

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Solution Overview

Problem

Conventional power tools require users to linearly actuate a switch to control rotational motion, making it difficult to directly compare trigger travel to output rotation and adjust speed finely, and they struggle with assessing joint tightness, leading to inefficient control and potential wrist strain.

Innovation Solution

A power tool design that uses rotational user input to control the output member, incorporating a rotational rate sensor and controller to monitor angular velocity, displacement, and direction, allowing intuitive control similar to manual screwdrivers and providing haptic feedback for improved user interaction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a linear trigger switch is used to control rotational motion, then the tool can be turned on and off, but it is difficult to directly compare trigger travel to output rotation and make quick speed adjustments

Engineering Contradiction:

Improvecontrol intuitivenessVSAvoidspeed adjustment precision

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces the traditional linear mechanical trigger switch with a rotary control mechanism that detects rotational motion of the tool body. This substitution allows the control input (rotation) to directly correspond to the output motion (rotation), providing intuitive control and precise speed adjustment through angular displacement sensing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention transitions from one-dimensional linear trigger movement to two-dimensional rotational control. By sensing angular displacement and rotational direction, the system adds dimensional complexity to the control interface, enabling more precise and intuitive speed control that matches the rotational nature of the output.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If the user grips the tool and actuates a linear switch, then the tool operates, but the user must first sense tightness with the wrist before making control adjustments

Engineering Contradiction:

Improvecontrol response timeVSAvoidjoint tightness assessment difficulty

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The patent replaces wrist-based tactile sensing with an electronic sensing system that detects rotational motion and torque characteristics through sensors. This substitution eliminates the delay between sensing joint tightness and making control adjustments, as the system continuously monitors operational parameters and automatically responds to changes in load conditions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If a linear trigger control is used, then the tool can be controlled, but the finger must travel linearly along one axis to control rotational motion about a different axis

Engineering Contradiction:

Improvecontrol alignment with output motionVSAvoidcontrol mechanism complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the complex mechanical linkage required to convert linear trigger motion to rotational control with an electronic sensing system. The rotary control mechanism with angular displacement sensors directly detects rotational input, eliminating the need for mechanical transformation mechanisms and simplifying the overall control system architecture.

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

This design enhances user control by allowing direct rotation-based input, improving speed adjustment precision and reducing wrist strain by providing intuitive and responsive control, enabling better management of joint tightness and tool operation.

Implementation Method 1

a rotational rate sensor and controller to monitor angular velocity, displacement, and direction

Methodology Applied

Scientific EffectRotational rate sensing: Gyroscope

Data Source

PatentEP2749376B1Power tool having rotary input control

Publication Date: 2020.11.04 BLACK & DECKER CORP

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AI summary

A power tool (10) includes a housing (12, 14), a motor (26), an output member (11) driven by the motor, and a reaming attachment (214) coupled to the output member. The reaming attachment has a front end portion selectively driven in rotation by the output member (11) to drive a fastener into a workpiece, and a reaming portion selectively driven in rotation by the output member to remove material from an end surface of a conduit. A rotational motion sensor (22) in the housing (12, 14) is operable to detect rotational motion of the housing about an axis. A controller (24) receives a signal indicative of rotational motion from the sensor, determines a direction of the rotational motion of the housing (12, 14), and drives the motor in a direction corresponding to the direction of rotational motion of the housing.