Battery-Powered Rescue Tool Speed Switching for Faster Piston Travel
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Solution Overview
Problem
Mobile electromechanical and electrohydraulic work tools face challenges in operational reliability and efficiency due to high mechanical stresses and long opening/closing times, particularly in rescue operations, where quick response is critical and inexperienced operators may misinterpret material resistance leading to inefficient cutting or extraction processes.
Innovation Solution
An electronic control and regulation unit that allows switching between two operating frequencies of a brushless direct current motor, enabling faster piston rod extension/retraction and incorporating a hydraulic control valve for intuitive operation, along with temperature and current monitoring to prevent overheating and optimize power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the electric motor operates at high frequency to extend the piston rod quickly, then the opening/closing time is reduced, but the energy consumption increases and overheating risk increases
Solution Approach 1:
The system dynamically adjusts the motor operating frequency based on real-time conditions. The control unit monitors current draw and temperature, switching between high frequency (second operating state) for rapid extension/retraction when conditions permit, and low frequency (first operating state) when thermal or power limits are approached. This dynamic adaptation resolves the contradiction by optimizing the time-energy tradeoff based on actual system state.
Solution Approach 2:
The control unit implements periodic monitoring of current and temperature parameters, using this feedback to determine when to switch between operating states. This periodic assessment allows the system to alternate between high-speed operation and energy-saving operation, resolving the contradiction through rhythmic adaptation to thermal and power constraints.
2Productivity
If the electric motor operates at high frequency to reduce operation time, then the productivity increases, but the reliability decreases due to overheating and mechanical stress
Solution Approach 1:
The control unit continuously monitors current draw and temperature as feedback parameters. When current exceeds the first threshold or temperature exceeds the second threshold, the system automatically transitions from high-frequency to low-frequency operation. This feedback mechanism ensures that productivity gains from high-speed operation do not compromise reliability through overheating or excessive mechanical stress.
Solution Approach 2:
The system proactively monitors thermal and power parameters before critical limits are reached. By detecting approaching thresholds and preemptively reducing motor frequency, the system cushions against potential overheating and mechanical failure, maintaining reliability while still achieving high productivity during safe operating windows.
3Device complexity
If a single pump system is used instead of two parallel pumps, then the device complexity is reduced, but the flexibility to operate at different frequencies is limited
Solution Approach 1:
Instead of using multiple pumps with different characteristics, the system changes the operating parameters (frequency) of a single pump. The control unit adjusts the motor frequency to match the requirements of different work tools, providing the same versatility as multiple pumps but with reduced complexity. This parameter-based adaptation resolves the contradiction between simplicity and flexibility.
4Reliability
If the control system monitors current and temperature continuously, then the reliability increases by preventing overheating, but the device complexity increases
Solution Approach 1:
The control unit performs self-monitoring of current and temperature parameters and automatically adjusts motor frequency based on these readings. This self-service capability eliminates the need for complex external monitoring systems or manual intervention, achieving reliable overheating prevention with minimal additional complexity. The system monitors itself and takes corrective action autonomously.
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 solution significantly reduces operation time, enhances the effectiveness of work tools by allowing faster switching between operating modes, improving operator intuition, and preventing mechanical issues and overheating, thus increasing the success rate of rescue operations.
Implementation Method 1
an electric motor (3), in particular a brushless direct current motor
Implementation Method 2
a hydraulic pump (2) driven by the electric motor (3)
Implementation Method 3
the heat (W) created by the drawn current (A) of the electric motor (3) during operation is measured
Data Source
AI summary
A portable tool, such as a spreader tool, cutting tool or combination spreading/cutting tool is for mobile use. The tool has an electric motor, a rechargeable battery received on the tool, a mechanically or hydraulically driven, displaceable piston rod for performing spreading and/or cutting and/or lifting or pressing. An electronic control and regulation unit controls/regulates the electric motor, such as a brushless DC motor. The electronic control and regulation unit specifies a first operating mode in which the electric motor is operated at a first frequency, and a second operating mode in which the electric motor is operated at a second frequency. The operating mode is switchable by an operator of the tool using a manually operable switch between the first and the second operating modes. The rotational speed of a three-phase current electric motor is higher at the second frequency than at the first frequency.