Toggle Link Mechanism for High Torque Electric Scissors
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Solution Overview
Problem
Conventional electric scissors face challenges in generating sufficient cutting torque without increasing weight, leading to durability issues and reduced operability due to large torque requirements during blade closure.
Innovation Solution
The implementation of a toggle link mechanism that increases the angle between links as the blades close, generating a large cutting torque in the latter half of the closing operation, allowing for efficient cutting without increasing the weight of the mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a large output motor is used to generate sufficient cutting torque at the beginning of blade closure, then the required cutting torque is achieved, but the load on the drive system increases and durability is degraded
Solution Approach 1:
The patent applies dynamics by making the transmission ratio variable rather than constant. The changeable transmission ratio mechanism allows the system to adapt the torque multiplication factor according to the cutting stage: higher ratios when torque is needed most (at closure), lower ratios when less torque is required, thereby reducing overall load on the drive system and improving durability while maintaining cutting effectiveness.
Solution Approach 2:
The patent changes the transmission ratio parameter dynamically during operation. By adjusting the transmission ratio according to the blade closing position, the system optimizes torque delivery: using higher transmission ratios when the blades are closing (when cutting torque is most needed) and lower ratios during other phases, thus reducing the motor output requirement and drive system load.
2Reliability
If the drive system is constructed sturdily to withstand large loads, then durability is improved, but the electric scissors become large in size and heavy in weight
Solution Approach 1:
The changeable transmission ratio mechanism allows the drive system to operate with variable loads rather than requiring constant high-strength components. The system uses higher torque multiplication only when needed during blade closure, allowing lighter motor and drive components to be used overall, thus reducing weight while maintaining durability through intelligent load management rather than brute-force oversizing.
3Reliability
If gears are increased in thickness to withstand large loads, then durability is improved, but the electric scissors become large in size and heavy in weight
Solution Approach 1:
The patent changes the transmission ratio parameter to reduce the peak loads that gears must withstand. By using variable transmission ratios that are optimized for different operating phases, the system reduces the maximum torque requirements, allowing thinner, lighter, and more compact gears to be used while maintaining sufficient durability for the intended application.
4Force
If a constant torque system is used, then cutting torque is available at all blade opening degrees, but the gears require increased thickness to withstand large loads
Solution Approach 1:
The patent implements a changeable transmission ratio that varies according to the blade closing position rather than maintaining a constant ratio. This allows the system to provide high torque when needed (at closure) while using lower torque multiplication during other phases, reducing the maximum loads on gears and allowing thinner, more durable gear design compared to constant torque systems.
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 necessary cutting torque without increasing the weight of the electric scissors, improving durability and operability by reducing the load on the drive system and making the tool more compact and lightweight.
Implementation Method 1
the electric scissors have a ball screw for converting a rotation of a motor into a linear motion of a nut portion
Implementation Method 2
The implementation of a toggle link mechanism that increases the angle between links as the blades close, generating a large cutting torque in the latter half of the closing operation
Data Source
AI summary
Electric scissors (1A, 1B) is provided with: a first blade (2A, 2B); a second blade (3A, 3B); a toggle link mechanism (7A, 7B) including a first link (71A, 71B), a second link (72A, 72B), and a drive shaft (70A, 70B); and a drive section (5, 6). One end of the first link (71A, 71B) is rotatably connected to a transmission portion (21A, 21B) of the first blade (2A, 2B). One end of the second link (72A, 72B) is rotatably connected to a transmission portion (31A, 31B) of the second blade (3A, 3B). The other end of the first link (71A, 71B) is rotatably connected to the other end of the second link (72A, 72B) through the drive shaft (70A, 70B). The drive section (5, 6) is configured to open/close the first blade (2A, 2B) and the second blade (3A, 3B) by displacing the drive shaft (70A, 70B) in a direction perpendicular to an axial direction of the drive shaft (70A, 70B).