Angle Grinder Yaw Rate Sensing for Jammed Tool Safety Control
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Solution Overview
Problem
Existing angle grinders lack effective detection and countermeasure systems to prevent potentially dangerous rotational movements of the housing, which can lead to operator safety risks during jammed tool situations.
Innovation Solution
Incorporating a yaw rate sensor to provide rotation parameters independently of housing acceleration, with a control and regulation unit that triggers a safety mode by detecting specific rotational movements, reducing the speed of the insert tool to prevent hazardous conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotation rate sensor is used to detect housing rotation, then operator safety is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical safety detection systems with an electronic gyroscope (rotation rate sensor) that electronically detects housing rotation around the tool axis. This electronic substitution provides more reliable and sensitive detection while the gyroscope's position independence simplifies installation, effectively resolving the contradiction between safety improvement and device complexity.
Solution Approach 2:
The gyroscope automatically detects housing rotation and provides signals to the control unit without requiring external intervention or complex mechanical linkages. The system self-monitors rotation parameters and triggers safety modes autonomously, improving reliability while minimizing additional complexity compared to manual or mechanically-linked safety systems.
2Reliability
If the safety mode reduces speed to below 5 rpm, then operator safety is improved, but productivity decreases
Solution Approach 1:
The patent implements dynamic speed control where the drive unit operates at full speed during normal conditions but automatically reduces to below 5 rpm when rotation is detected. This dynamic adjustment ensures maximum safety during hazardous situations while maintaining full productivity during normal operation, resolving the contradiction between safety and productivity through conditional speed modulation.
Solution Approach 2:
The system changes the operational parameter (rotational speed) from high speed (full productivity) to low speed (below 5 rpm) based on detected conditions. This parameter change enables the system to optimize between productivity and safety by operating at different speed levels depending on the operational state, with automatic restoration of full speed once the hazardous condition is resolved.
3Ease of manufacture
If the gyroscope is positioned anywhere in the housing, then ease of manufacture is improved, but measurement precision may worsen
Solution Approach 1:
The patent selects a gyroscope type that provides universal rotation detection capability, allowing the sensor to be positioned at multiple locations within the housing while maintaining measurement accuracy. This universal sensor design enables flexible installation (improving ease of manufacture) while the sensor's inherent capabilities ensure measurement precision is maintained across different positions, resolving the contradiction between manufacturing ease and measurement accuracy.
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
The system effectively detects and mitigates dangerous rotational movements by initiating a safety mode, reducing the speed of the insert tool to a safe level, thereby enhancing operator safety and preventing unnecessary shutdowns.
Implementation Method 1
the sensor device includes a gyroscope (20) designed to provide the rotation parameter as a function of a housing rotation movement
Data Source
Figure 1
AI summary
The invention relates to an angle grinder (10), comprising a housing (22), a drive unit (12) for driving a usage tool (14) having a sensor device (16) for providing a rotation parameter and a control unit (18) for evaluating the rotation parameter in order to detect a clamped state of the usage tool (14). The sensor device (16) has a yaw rate sensor (20) for providing the rotation parameter in accordance with a rotational movement of the housing. In one embodiment, the control unit (18) triggers a safety mode in accordance with the rotation parameter or throttles the rotational speed and/or torque of the drive unit (12).