Power Tool Axial Penetration Depth Measurement

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing power tools face challenges in accurately measuring penetration depth without parallax errors, particularly in hand-held power tools, where mechanical depth stops are cumbersome and electronic methods using ultrasound or electromagnetic waves can be prone to measurement errors due to tool axis inclination.

Innovation Solution

A power tool equipped with a signal processor and transducer that uses high-frequency electromagnetic waves propagating axially along the working tool to determine penetration depth, utilizing a coaxial conductor system and signal processing to detect voltage signals from wave reflections, allowing for parallax-free measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If mechanical depth stops are used to measure penetration depth, then the measurement can be obtained, but the device complexity increases and ease of operation deteriorates due to requiring three hands for adjustment

Engineering Contradiction:

Improvepenetration depth measurementVSAvoiddepth stop adjustment

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces the mechanical depth stop system with an electronic measurement system using ultrasound transducers. The transducers emit ultrasound waves that reflect off the material surface, and the penetration depth is calculated from the time of flight of the waves, eliminating the need for manual mechanical adjustment and improving ease of operation while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If electronic depth stops using ultrasound or electromagnetic waves are used, then ease of operation improves, but measurement precision deteriorates due to parallax errors from tool axis inclination

Engineering Contradiction:

Improvedepth measurement operationVSAvoidpenetration depth measurement

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent measures penetration depth along the tool axis direction using ultrasound waves propagating axially, rather than measuring from a lateral reference point. This axial measurement approach eliminates parallax errors that occur when measuring from the side, as the measurement is taken directly along the drilling direction where the tool axis inclination does not create angular measurement errors.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Measurement precision

If mechanical depth stops are used, then device complexity increases due to axial displacement and rotational constraints, but measurement precision is maintained

Engineering Contradiction:

Improvepenetration depth measurementVSAvoiddepth stop structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex mechanical depth stop structure with a simpler electronic system consisting of ultrasound transducers and signal processing circuitry. The transducers are mounted on the tool body and emit waves that travel axially to the material surface, with depth calculated electronically from wave travel time, eliminating mechanical displacement mechanisms and rotational constraints while maintaining accurate penetration depth measurement.

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 accurate and efficient measurement of penetration depth without the limitations of mechanical stops or parallax errors, improving user convenience and measurement precision by using high-frequency electromagnetic waves to determine the tool's position within the material.

Implementation Method 1

a transducer (5) which is suitable for exciting and detecting a high-frequency electromagnetic wave (4) propagating axially along the working tool (3)

Methodology Applied

Scientific EffectElectromagnetic wave propagation: Electromagnetic Induction

Implementation Method 2

the wave is at least partially reflected at that location. The electric field strength of the wave can be detected at the transducer by means of a voltage measurement

Methodology Applied

Scientific EffectElectromagnetic wave reflection: Reflection

Implementation Method 3

a change in the dielectric (from ∈=1 for air to ∈=3.5 for mineral substrates) and accordingly of the characteristic impedance likewise takes place at the surface of the to-be-machined material

Methodology Applied

Scientific EffectDielectric permittivity change: Dielectric Permittivity

Data Source

PatentUS7482819B2Power tool with measurement of a penetration depth of a working tool

Publication Date: 2009.01.27 HILTI AG

AI summary

A power tool (1) for driving a working tool (3) that penetrates at least axially into a to-be-machined material (2), and including a signal processor (6, 6′), and a transducer (5) which is suitable for exciting and detecting a high-frequency electromagnetic wave (4) propagating axially along the working tool (3) and which is connected to the signal processor (6, 6′) that is designed to determine the penetration depth (T) of the working tool (3) into the material (2) based on high-frequency electromagnetic waves (4).