Power Tool Impulse Assembly Thermal Control via Indirect Sensor

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Solution Overview

Problem

Impulse power tools experience thermal failure due to hydraulic fluid temperature, which is difficult to measure directly, making it challenging to prevent such failures.

Innovation Solution

A system and process using temperature sensors positioned away from airflow circulation paths, such as on light assembly or Hall effect sensor PCBs, to indirectly measure the hydraulic fluid temperature and control the power tool based on correlated temperature thresholds, including shutdown or output reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If temperature sensors are positioned within the impulse assembly to directly measure hydraulic fluid temperature, then measurement precision is improved, but device complexity and difficulty of detecting and measuring are worsened

Engineering Contradiction:

Improvehydraulic fluid temperature measurementVSAvoidtemperature sensor positioning

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent uses temperature sensors positioned on external components (light assembly PCB, Hall effect sensor PCB, motor housing) as intermediaries to indirectly measure the hydraulic fluid temperature. These external sensors act as mediators that correlate their temperature readings to the internal fluid temperature, avoiding the complexity of direct measurement while maintaining sufficient measurement precision for thermal failure prevention

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical approach of directly inserting temperature sensors into the impulse assembly with an electronic field-based approach. Temperature sensors on external PCBs and motor housing use thermal conduction and correlation algorithms to determine fluid temperature, substituting direct mechanical measurement with indirect electronic sensing and computational inference

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If temperature sensors are positioned away from airflow circulation paths, then measurement precision of fluid temperature is improved, but the temperature sensors may be exposed to ambient temperature interference

Engineering Contradiction:

Improvefluid temperature correlationVSAvoidambient temperature interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback-based temperature control system where the controller continuously monitors temperature sensor readings and compares them against threshold values. When the correlated fluid temperature exceeds the threshold, the controller automatically shuts down the motor, creating a closed-loop feedback system that compensates for ambient temperature interference by using real-time temperature data to adjust operation

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the measurement parameter from direct hydraulic fluid temperature to correlated temperature based on external sensor readings. By positioning sensors away from airflow paths and using thermal correlation algorithms, the system transforms the measurement approach to reduce ambient interference while maintaining the ability to detect thermal failure conditions

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the power tool is shut down when temperature exceeds threshold, then reliability is improved, but productivity is worsened

Engineering Contradiction:

Improvethermal failure preventionVSAvoidoperational continuity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements periodic temperature monitoring and control, where the controller continuously checks temperature sensor readings at regular intervals during operation. This periodic detection allows the system to maintain operation within safe temperature ranges while automatically shutting down only when thermal failure is imminent, balancing reliability with productivity through time-based monitoring cycles

Inventive Principle:

Principle #19Periodic action

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

Effectively prevents thermal failure by controlling the power tool operation based on correlated fluid temperature, ensuring safe and efficient operation.

Implementation Method 1

The temperature sensor is configured to output a signal related to a temperature of the power tool. The temperature of the power tool is correlated to a temperature of a fluid within the impulse assembly.

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

When the hydraulic fluid reaches a certain temperature, an impulse tool may experience thermal failure.

Methodology Applied

Scientific EffectViscous heating: Viscous Heating

Data Source

PatentUS20250276430A1Power tool with impulse assembly

Publication Date: 2025.09.04 MILWAUKEE ELECTRIC TOOL CORP

AI summary

A power tool including a motor, an impulse assembly configured to be driven by the motor, a temperature sensor, and a controller. The temperature sensor is configured to output a signal related to a temperature of the power tool. The temperature of the power tool is correlated to a temperature of a fluid within the impulse assembly. The controller is connected to the temperature sensor. The controller is configured to determine the temperature of the power tool based the signal from the temperature sensor, and control, in response to the temperature of the power tool being greater than a temperature threshold, the power tool based on the temperature of the power tool.