Power Tool Motor Current Monitoring for Load Sensing

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Solution Overview

Problem

Existing power tools face challenges in miniaturization and cost reduction due to the addition of pressure sensors for reliability improvement, which increases manufacturing costs and occupies more space.

Innovation Solution

A power tool that monitors its operation status by detecting and tracking motor current, using a microprocessor, current detecting-and-converting module, and drive unit to convert motor current into a pressure value for load monitoring and motor protection, eliminating the need for additional pressure sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pressure sensors are added to improve reliability, then the reliability is improved, but the manufacturing cost increases and space occupied increases

Engineering Contradiction:

ImprovereliabilityVSAvoidspace occupied

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the pressure sensing function from a dedicated pressure sensor and relocates it to the motor control system by measuring motor current. This eliminates the need for separate pressure sensors while maintaining the ability to monitor hydraulic pressure, thereby reducing device complexity and space occupation while preserving reliability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The motor control system is given multiple functions: it not only controls motor operation but also serves as the pressure detection system by analyzing motor current characteristics. This multi-functionality eliminates the need for dedicated pressure sensors, reducing overall device complexity while maintaining reliable pressure monitoring capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If pressure sensors are added to improve reliability, then the reliability is improved, but the manufacturing cost increases

Engineering Contradiction:

ImprovereliabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the pressure detection function with the motor control function by using motor current measurements to infer hydraulic pressure. This consolidation eliminates separate pressure sensor components and their associated circuitry, thereby reducing manufacturing cost while maintaining the ability to provide reliable pressure-based protection and control.

Inventive Principle:

Principle #5Merging (Combining)

3Device complexity

If mechanical pressure relief control is used, then the structure is simple, but the reliability is reduced

Engineering Contradiction:

ImprovestructureVSAvoidreliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces mechanical pressure relief control with an electrical control system that uses motor current sensing and microprocessor-based analysis. This substitution maintains the simplicity of not having separate pressure sensors while dramatically improving reliability through electronic monitoring and control capabilities, allowing for more precise and responsive pressure management.

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 solution allows for effective load monitoring and motor protection at lower costs and with reduced space usage, enhancing the power tool's reliability and safety without the need for additional pressure sensors.

Implementation Method 1

Detect a per unit time current and convert the per unit time motor current into a pressure value

Methodology Applied

Scientific EffectElectrical measurement and conversion: Ohm's Law

Data Source

PatentUS10566918B1Power tool monitored by tracking a motor current and control methods thereof

Publication Date: 2020.02.18 KUDOS MECHANICAL CO LTD

AI summary

The present invention relates to a power tool monitored by tracking a motor current and control methods thereof. The present invention is mainly about a microprocessor electrically connected to a motor through a drive unit and a current detecting-and-converting module. The microprocessor receives an AC synchronizing signal, and sends a first control signal to the drive unit according to the AC synchronizing signal to drive the motor. The current detecting-and-converting module detects and converts the motor current and output to the microprocessor, thereby the microprocessor detects a per unit time current which is converted into a corresponding pressure value, and then the microprocessor sends a second control signal to the drive unit according to the pressure value to control the operation status of the motor. By detecting and tracking the per unit time current, the purpose of load monitoring and motor protection can be achieved.