Electric Scissors Current Control for Torque and Weight
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Solution Overview
Problem
Existing electric scissors face a challenge in balancing high cutting torque with reduced part load, leading to increased weight and decreased usability due to the need for stronger parts to handle high torque during blade closure.
Innovation Solution
The implementation of a motor with a speed reducer using planet gears and a motion direction converter that adjusts the electric current supply based on blade position, limiting the current to prevent excessive torque and load on the link mechanism, allowing for effective cutting torque without overloading parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the strengths of the parts are increased to handle high cutting torque, then the cutting performance is improved, but the weight is increased and usability is deteriorated
Solution Approach 1:
The patent applies dynamics by making the electric current supply variable based on blade position. The control unit adjusts the current limit according to the angle between links, providing high torque when needed (second half of closing operation) and reducing torque when not needed (first half and when fully closed). This dynamic control allows using lighter parts while maintaining sufficient cutting torque during the critical phase.
Solution Approach 2:
The patent changes the parameter of electric current supply based on the operational state. By varying the current limit according to the angle between links (detected by the angle detection unit), the system optimizes torque output dynamically. This parameter change enables lighter part design since the maximum torque is only required during specific phases of the closing operation, not continuously.
2Force
If high cutting torque is generated in the second half of blade closing operation, then cutting performance is improved, but the load on parts is increased
Solution Approach 1:
The patent implements periodic action by dividing the blade closing operation into phases based on the angle between links. The control unit provides high current (and thus high torque) only during the second half of the closing operation when the angle is within a specific range, and reduces current when the blades are fully closed or in the opening phase. This periodic torque application matches the actual cutting needs while reducing overall load on parts.
Solution Approach 2:
The system dynamically adjusts torque output based on real-time detection of the angle between links. The control unit continuously monitors the angle and modulates the motor current accordingly, providing high torque precisely when cutting force is needed (second half of closing) and minimizing torque when not needed, thereby reducing cumulative load on mechanical parts.
3Stress or pressure
If the electric current supply is controlled based on blade position, then the load on parts is reduced, but the device complexity is increased
Solution Approach 1:
The patent uses feedback by incorporating an angle detection unit that continuously monitors the angle between links and provides this information to the control unit. The control unit then adjusts the current limit based on the detected angle, creating a closed-loop control system. This feedback mechanism enables intelligent torque management while keeping the control logic relatively simple (comparing angle to predetermined thresholds and adjusting current accordingly).
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 the generation of high cutting torque while maintaining a reduced load on the electric scissors' parts, thereby minimizing the weight and enhancing usability by controlling the electric current supply in conjunction with a detection unit that adjusts the torque based on blade position.
Implementation Method 1
a speed reducer 24 in which a rotating shaft adopts planet gears
Implementation Method 2
a speed reducer 24 in which a rotating shaft adopts planet gears
Implementation Method 3
a screw shaft 25 that is connected to an output shaft of the speed reducer 25 and a nut portion 26 that is linearly moved along the screw shaft 25
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
In electric scissors, a rotating motion of a motor (21) is converted into a linear motion, and a link mechanism (A) is operated to open and close blades (11, 12) by the linear motion. The electric scissors includes a current control unit (110) that controls an electric current value to the motor (21), and a detection unit (120) that detects that an angle between the blades (11, 12) becomes a predetermined angle. The current control unit (110) changes an upper limit of the electric current value to be supplied to the motor (21) when the detection unit (120) detects that the angle between the blades (11,12) becomes the predetermined angle.