Pneumatic Power Tool Control via Acceleration Thresholds

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Solution Overview

Problem

Electro-pneumatically striking hand-held power tools consume excessive power when lifted off a workpiece, leading to inefficient operation and potential user fatigue due to continued activation during empty strikes.

Innovation Solution

A method that detects acceleration thresholds to differentiate between intended operation and empty strikes, reducing driving power when excessive acceleration is detected, and adjusting power levels based on rotational speed to minimize energy consumption during idle states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the electro-pneumatic striking mechanism remains active during empty strikes (when the tool is lifted off the workpiece), then the tool is ready for immediate operation, but power consumption increases excessively

Engineering Contradiction:

Improvereadiness for operationVSAvoidpower consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the striking mechanism's operational state adjustable between active and reduced-power modes based on detected acceleration patterns. The system dynamically transitions between states rather than remaining static, allowing it to adapt to whether the tool is in use or idle, thus resolving the contradiction between readiness and power consumption.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent uses feedback from acceleration sensors to detect whether the tool is performing intended operation or empty strikes. This feedback loop allows the control system to automatically adjust the striking mechanism's power state, switching to reduced power consumption mode when empty strikes are detected, thereby reducing excessive power usage while maintaining operational readiness when needed.

Inventive Principle:

Principle #23Feedback

2Productivity

If the striking mechanism operates at full power continuously, then productivity is maintained, but energy is wasted during idle states when no workpiece contact occurs

Engineering Contradiction:

Improvestriking outputVSAvoidenergy waste during idle states

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent implements periodic action by using rhythmic acceleration patterns detected during operation to determine whether the tool is in intended use or performing empty strikes. By analyzing periodic acceleration signals, the system can distinguish between productive work cycles and idle cycling, enabling it to reduce power consumption during idle periods while maintaining full productivity during actual work.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent changes operational parameters (power delivery to the striking mechanism) based on detected acceleration patterns. When acceleration patterns indicate empty strikes rather than intended operation, the system changes the power parameter from full output to reduced output, thereby eliminating energy waste during idle states while preserving productivity during actual work.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If acceleration threshold detection is used to distinguish empty strikes from intended operation, then power consumption is reduced, but the device complexity increases due to additional sensors and control logic

Engineering Contradiction:

Improvepower consumptionVSAvoidcontrol system complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent applies self-service by using the tool's own operational characteristics (acceleration patterns during striking) to automatically determine whether it is in use or idle. The system serves itself by detecting its own operational state through acceleration sensors and autonomously adjusting power consumption accordingly, without requiring external monitoring or complex external control systems.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces complex mechanical monitoring systems with electronic acceleration sensing and digital signal processing. Instead of using mechanical switches or complex mechanical feedback mechanisms to detect operational state, the system uses electronic accelerometers and software-based pattern recognition, thereby reducing overall device complexity while achieving power consumption reduction.

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 approach effectively reduces power consumption and minimizes user fatigue by distinguishing between active and idle states, ensuring optimal power usage and tool longevity.

Implementation Method 1

the acceleration that is present along a striking direction of the hand-held power tool is detected

Methodology Applied

Scientific EffectAcceleration detection: Accelerometer

Data Source

PatentUS8333251B2Control method and hand-held power tool

Publication Date: 2012.12.18 HILTI AG

AI summary

A pneumatically striking hand-held power tool is controlled by the following steps. An acceleration (a) along a striking axis (8) of the hand-held power tool (1) is detected. A driving power is reduced if the detected acceleration (a) is greater than a threshold value (A), the threshold value (A) being selected to be greater than maximum acceleration values (a1, a2) that occur on a workpiece during the striking operation of the hand-held power tool (1).