Battery Activation Logic for Drop-Safe Power Tool Operation

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Solution Overview

Problem

Existing control methods for accumulators in hand-held power tools do not adequately protect against damage from drops, particularly due to insufficient consideration of the tool's characteristics and safety thresholds.

Innovation Solution

A control method that activates the accumulator based on machine and accumulator characteristics, switching between operating states to prevent energy draw when safety thresholds are exceeded or fallen below, using a logic circuit to ensure compatibility and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the accumulator is always activated to supply electrical energy, then the power tool can operate continuously, but the accumulator is vulnerable to damage from drops

Engineering Contradiction:
Improvecontinuous operation capabilityVSAvoidaccumulator protection against drop damage
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The logic circuit performs preliminary evaluation of the system characteristic (fall energy) before activating the accumulator. By calculating the fall energy based on machine characteristic and accumulator characteristic, and comparing it against a predetermined safety threshold, the system determines in advance whether the accumulator should be activated, preventing damage before it occurs

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The accumulator's operational state is made dynamic rather than static. The logic circuit continuously monitors system characteristics and adjusts the accumulator's activation state based on real-time conditions. The power tool switches between first operating state (no energy draw) and second operating state (energy draw permitted) based on whether the fall energy exceeds the safety threshold

Inventive Principle:
Principle #15Dynamics

2Reliability

If the accumulator is activated only when safety thresholds are met, then protection against drop damage is improved, but the power tool cannot operate when thresholds are exceeded

Engineering Contradiction:
Improveaccumulator protection against drop damageVSAvoidpower tool operation availability
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The logic circuit implements a feedback mechanism that continuously monitors the system characteristic (fall energy) and adjusts the accumulator's operational state accordingly. When the fall energy exceeds the safety threshold, the logic circuit deactivates the accumulator or prevents energy draw, and when the threshold is not exceeded, the accumulator is activated. This closed-loop control ensures the accumulator operates only under safe conditions

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4440787B1Control method for a battery
Publication Date: 2026.03.18 HILTI AG
  • EP4440787B1 patent drawingFigure 1
  • EP4440787B1 patent drawing

AI summary

The invention relates to a control method for a rechargeable battery which has an interface for communicating with a hand-held power tool and for supplying power to the hand-held power tool, wherein a tool characteristic value which characterises the hand-held power tool is received via the interface of the rechargeable battery, wherein the tool characteristic value represents at least one physical property of the hand-held power tool, and the rechargeable battery is activated to output electrical energy to the hand-held power tool if a logic circuit of the rechargeable battery determines that a system characteristic value which is based on the tool characteristic value and on a rechargeable battery characteristic value representing a physical property of the rechargeable battery, is above or below a predefined safety threshold.