Hand Tool Motor Braking via Segmented Current Control
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Solution Overview
Problem
Existing hand tools with electric motors face challenges in achieving rapid and efficient braking while minimizing component stress, leading to potential damage and reduced durability due to high kinetic energy and dynamic braking processes.
Innovation Solution
A method that combines short-circuit braking and counter-current braking, where the first phase involves short-circuit braking to reduce kinetic energy moderately and the second phase uses counter-current braking to achieve active deceleration, with the duration of each phase controlled to avoid exceeding maximum current or voltage values, thereby reducing component loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If countercurrent braking is used to achieve rapid deceleration, then braking time is reduced, but component loads increase
Solution Approach 1:
The braking process is divided into multiple phases: a first phase using countercurrent braking for rapid deceleration, followed by a second phase using short-circuit braking to complete the stopping process. This segmentation allows the system to achieve fast braking while limiting the duration and intensity of high-stress countercurrent braking, thereby reducing overall component loads.
Solution Approach 2:
The control device alternates between countercurrent braking and short-circuit braking in periodic phases. During the first phase, countercurrent braking is applied to achieve rapid speed reduction; during the second phase, short-circuit braking is applied to complete the deceleration with minimal stress. This periodic switching optimizes the balance between braking speed and component protection.
2Productivity
If active braking mode is used to achieve rapid deceleration, then braking effectiveness is improved, but risk of high component loads increases
Solution Approach 1:
The braking process is segmented into an active braking phase (countercurrent) and a passive braking phase (short-circuit). The active phase achieves rapid deceleration when needed, while the passive phase completes the stopping with minimal component stress, thus maintaining both effectiveness and reliability.
Solution Approach 2:
The control device dynamically changes the braking parameter (from countercurrent to short-circuit) based on the current operating state and detected variables. This parameter change allows the system to transition from high-effectiveness active braking to low-stress passive braking, optimizing both productivity and reliability.
3Duration of action of moving object
If high deceleration is applied to quickly stop the tool, then tool standstill time is reduced, but component stress increases
Solution Approach 1:
The deceleration process is segmented into two distinct phases: high-deceleration countercurrent braking followed by low-deceleration short-circuit braking. This segmentation enables the tool to reach standstill quickly while limiting the duration of high-stress conditions, thus reducing overall component stress.
Solution Approach 2:
The braking system dynamically adjusts the deceleration rate by switching between countercurrent and short-circuit modes. The control device monitors operating state variables and adapts the braking strategy in real-time, applying high deceleration when safe and transitioning to low-stress braking as the tool approaches standstill.
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 approach enables a targeted braking effect with minimal component stress, ensuring the longest possible tool standstill while maintaining component durability and safety, potentially replacing or extending mechanical brakes without additional components.
Implementation Method 1
an first time segment, in which the drive motor (16) is short-circuited
Implementation Method 2
a second time segment, in which the drive motor (16) is energized with counter-current
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to a method for decelerating a drive movement of a hand tool and a hand tool suitable for carrying out the method, comprising a drive motor (16) that can be coupled to an output (18), a power supply device (62) for providing electrical energy, a control device (58) with a motor control (60) for controlling the drive motor (16) and an operating state detection module (61) that is configured to detect at least one operating state variable and, depending thereon, to output a brake signal, wherein the control device (58) is configured to initiate a braking procedure depending on the brake signal, in which braking cycles are provided that have a first time period (Δt1) in which the drive motor (16) is short-circuited, and a second time period (Δt2) in which the drive motor (16) is energized in the opposite direction to its original direction of rotation (Fig. 2).