Electric Screwdriver Countercurrent Braking for Clutch Repeatability
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Solution Overview
Problem
Industrial shut-off clutch screwdrivers require constant rotational speed and efficient braking to prevent overrunning, which existing technologies fail to achieve effectively, leading to reduced repeatability and increased energy dissipation as heat.
Innovation Solution
The implementation of countercurrent braking in electric motor control systems for power tools, which generates a counter-field to efficiently stop the motor and dissipate parasitic electrical currents into the energy storage device, eliminating the need for brake choppers and enhancing tool robustness and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional braking methods are used, then the motor can be stopped, but the braking time and motor revolutions during braking are excessive, causing the overrunning clutch to overrun a second time and reducing repeatability
Solution Approach 1:
The patent converts the parasitic electrical current generated during countercurrent braking from a harmful factor into a beneficial resource by channeling it to charge the energy storage device. This approach simultaneously achieves efficient motor braking (reducing braking time and revolutions) and recovers energy, while preventing overrunning clutch issues and maintaining repeatability
2Productivity
If countercurrent braking is implemented, then braking efficiency is improved and parasitic currents are generated, but these parasitic currents can damage the intermediate circuit
Solution Approach 1:
The patent transforms the harmful parasitic electrical current generated during countercurrent braking into a useful charging current for the energy storage device. The control device manages this current to charge the battery, thereby eliminating the risk of intermediate circuit damage while maintaining high braking efficiency
3Object-affected harmful factors
If brake choppers are used to dissipate parasitic currents, then circuit protection is achieved, but installation space and heat dissipation requirements increase
Solution Approach 1:
Instead of using brake choppers to dissipate parasitic currents as heat, the patent channels these currents to charge the energy storage device. This eliminates the need for brake choppers and associated heat dissipation components, significantly reducing installation space while maintaining circuit protection and adding energy recovery functionality
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 enables efficient braking and charging of energy storage devices, reducing heat dissipation, installation space, and material usage, resulting in a compact, lightweight, and high-repeatability power tool with extended service life.
Implementation Method 1
Countercurrent braking includes generation of a counter-field on the rotor by the stator of the electric motor
Implementation Method 2
a parasitic electrical current generated by the countercurrent braking can be discharged into the energy storage device in order to charge the energy storage device
Data Source
AI summary
A power tool, in particular an electric screwdriver, includes (i) a housing; (ii) an electric motor which is located in the housing and by way of which an insert tool located in a tool holder can be rotationally driven; (iii) and a control device which is designed to control a braking process of the electric motor in response to a braking request in order to stop the rotating insert tool. The braking process includes countercurrent braking. A method for braking an electric motor of a power tool, a computer program, and a machine-readable storage medium are also disclosed.