Battery Pack Stress Detection via Acceleration and Piezoelectric Sensors

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Solution Overview

Problem

Modern power tools and batteries can withstand mechanical stress and abuse but it is difficult for users to determine if they have been damaged, posing a safety risk when continuing to operate the system after exposure to mechanical stress or strain.

Innovation Solution

A system comprising a power tool and battery with acceleration sensors for detecting acceleration values in X, Y, and Z directions, piezoelectric sensors, a controlling device, signal transmitter, and voltage measurement device to determine vibrations, drops, impacts, and voltage changes, sending signals to indicate potential damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the system continues operating after mechanical stress, then productivity is maintained, but safety and reliability deteriorate due to potential undetected damage

Engineering Contradiction:
Improvecontinuous operationVSAvoidsystem safety
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system performs preliminary detection of mechanical stress events (drops, impacts, shocks) using acceleration sensors and piezoelectric sensors before damage occurs. By detecting and recording these events in advance, the system can evaluate potential damage and alert users before operating in a compromised state, thus maintaining both productivity and reliability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by continuously monitoring acceleration values and piezoelectric sensor signals, evaluating whether mechanical stress thresholds are exceeded, and providing real-time alerts to users. This feedback loop enables users to stop operation when damage is detected, preventing further degradation while maintaining productivity during normal operation.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If multiple sensors and monitoring functions are added, then detection precision and safety are improved, but device complexity increases

Engineering Contradiction:
Improvemechanical stress detectionVSAvoidsystem structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system merges multiple sensing functions into a unified monitoring structure. Acceleration sensors and piezoelectric sensors are integrated to detect different aspects of mechanical stress (drops, impacts, shocks), and their signals are processed together by a single controlling device. This combining approach improves measurement precision while managing device complexity through functional integration.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The controlling device serves multiple functions: it processes signals from both acceleration sensors and piezoelectric sensors, evaluates different types of mechanical stress, determines damage levels, and provides user alerts. This multi-functionality allows the system to achieve comprehensive detection precision without proportionally increasing device complexity, as one component performs multiple evaluation tasks.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

The system effectively monitors and alerts users to potential mechanical stress, enabling safer operation by distinguishing between non-harmful and harmful conditions, thus preventing potential hazards from undamaged power tools and batteries.

Implementation Method 1

at least one piezoelectric sensor

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

at least one acceleration sensor for detecting at least one acceleration value in an X, Y and Z direction

Methodology Applied
Scientific EffectGravitation: Gravitation

Data Source

PatentEP3990227B1Sensor to detect a mechanical stress on the battery pack
Publication Date: 2024.03.20 HILTI AG
  • EP3990227B1 patent drawingFigure 1
  • EP3990227B1 patent drawingFigure 2
  • EP3990227B1 patent drawingFigure 3

AI summary

A method for controlling a system comprising a power-tool and a battery having energy storage cells, wherein the system comprises an acceleration sensor, a piezoelectric sensor, a controlling device, signal transmitter and a device for measuring a voltage. Method comprises the steps: - Determining vibration values acting upon the system by detecting accelerations values within a predetermined range; - Determining that the system is free-falling by detecting an acceleration value in the X, Y and Z direction being equal to a predetermined range; - Determining an impact of the system by detecting an acceleration value in the X, Y and Z direction exceeding a first predetermined threshold value; - Determine a traveling distance between detecting an acceleration value in the X, Y and Z direction being equal to a predetermined range and detecting an acceleration value in the X, Y and Z direction exceeding the first predetermined threshold value; - Determining a shock value by means of the piezoelectric sensor or the acceleration sensor; - Detecting a first and second voltage value by means of the device for measuring a voltage; and - Sending out a first signal if the accelerations values within the predetermined range for determining vibrations exceed a first predetermined threshold value for a first predetermined time period, the determined drop height exceeds a first predetermined threshold value, the detected value for determining a shock exceeds a first predetermined threshold value or a difference value between the first and second voltage value exceeds a first predetermined threshold value. A system for carrying out the method comprising a power-tool and at least one battery having at least one energy storage cell with an acceleration sensor, a controlling device, an interface for an exchange of data, a piezoelectric sensor, a signal transmitter and the power tool and a device for measuring a voltage.