Power Tool Transmission Backlash Detection from Drag Torque
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Solution Overview
Problem
Existing power tools lack a simple and efficient method to detect transmission backlash, which can lead to unexpected failures and require complex maintenance, especially in tools with variable operating conditions and different applications.
Innovation Solution
A procedure that actuates the drive motor of a power tool until a constant drag torque is achieved, then measures the change in drive shaft rotation to determine the transmission backlash, allowing for predictive maintenance without additional sensors or complex inspections, and can be retrofitted as a software update.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex additional sensors or complex inspection measures are provided to detect transmission backlash, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The power tool uses its own existing operational parameters (drag torque and drive shaft rotation) to detect transmission backlash, without requiring external sensors or inspection systems. The control unit processes data already generated during normal operation, making the system self-diagnostic and eliminating the need for additional detection equipment.
Solution Approach 2:
The patent replaces potential mechanical sensor-based detection systems with an electronic control system that analyzes operational parameters. The control unit calculates backlash based on electrical measurements of drag torque and rotational position, substituting mechanical measurement approaches with electronic data processing.
2Reliability
If traditional inspection methods are used to detect transmission backlash, then reliability is improved, but ease of operation deteriorates
Solution Approach 1:
The control unit continuously monitors drag torque and drive shaft rotation during operation, providing real-time feedback about transmission condition. This feedback mechanism enables the system to automatically detect backlash and communicate maintenance needs to the user, making reliability monitoring as easy as operating the tool.
Solution Approach 2:
The control unit acts as an intermediary between the transmission system and the user, translating complex mechanical conditions into simple operational information. It processes raw sensor data and presents maintenance status in an easily understandable format, bridging the gap between complex mechanical states and user decision-making.
3Productivity
If the power tool is operated under load during detection, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
The system performs backlash detection during brief intervals when the tool is not under load, such as during mode transitions or idle periods between tasks. By utilizing these preliminary opportunities for measurement, the system maintains productivity while ensuring accurate readings are taken under appropriate conditions.
Solution Approach 2:
The control unit periodically checks transmission backlash during operation by utilizing regular idle moments or transition periods. This periodic measurement approach ensures continuous monitoring capability while maintaining productive operation during loaded periods, balancing measurement needs with productivity requirements.
Data Source
AI summary
A method for detecting a transmission backlash in a hand-held power tool, the hand-held power tool comprising a drive motor that has a drive shaft, a tool spindle, and a transmission that, in respect of drive, connects the drive shaft to the tool spindle, includes actuating, in a first actuation, the drive motor at least until the value of a first variable, representing a drag torque, is at least approximately constant. The method includes, during the first actuation, determining a value of a second variable which is associated with the rotation of the drive shaft of the drive motor during the first actuation, and determining a value of a third variable, representing a transmission backlash, based upon a change in the second variable during the first actuation.