Magnetic Torque Limiting Device for Surgical Instrument Drive Train
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Solution Overview
Problem
Current surgical staplers lack efficient control over power and speed, and their battery management systems are not optimized for prolonged use, leading to potential damage from excessive torque and inadequate power delivery during procedures.
Innovation Solution
The development of cordless motor-powered surgical cutting and fastening instruments with a power pack comprising DC power sources, a cell selection switch, and a power regulator, along with secondary accumulator devices like rechargeable batteries or supercapacitors, which include a charge management circuit and torque-limiting devices to control motor output and prevent component damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If motor-powered surgical instruments use high power output to ensure adequate power delivery during procedures, then power delivery capability is improved, but risk of component damage from excessive torque increases
Solution Approach 1:
The patent applies parameter changes by implementing a torque limiting device that dynamically adjusts and controls the torque parameter delivered by the motor. The device restricts the maximum torque to a predetermined safe level, preventing component damage while maintaining adequate power delivery for surgical procedures. This resolves the contradiction by modifying the torque parameter to balance power capability with component protection.
Solution Approach 2:
The torque limiting device acts as an intermediary component between the motor and the surgical instrument's mechanical components. It mediates the power transmission by selectively limiting torque, allowing adequate power delivery while protecting downstream components from excessive torque. This intermediary function resolves the contradiction by decoupling the motor's high power capability from the mechanical components' torque exposure.
2Power
If battery management systems operate at maximum power output to optimize procedure duration, then power availability is improved, but battery depletion rate increases
Solution Approach 1:
The patent applies dynamics by implementing a cell selection switch that dynamically adjusts the number of battery cells connected to the motor based on procedural needs. The system can transition between different power configurations, allowing the battery management system to optimize between power availability and operational duration. This resolves the contradiction by enabling dynamic adaptation of power output to match actual procedural requirements.
Solution Approach 2:
The patent applies partial action by allowing the operator to select only the necessary number of battery cells for the specific surgical procedure. Rather than always operating at maximum power, the system enables partial power delivery appropriate to the procedural needs, thereby extending battery operational duration while maintaining adequate power availability for the intended task.
3Reliability
If surgical instruments use mechanical clutch devices for torque limiting, then component protection is improved, but device complexity increases
Solution Approach 1:
The patent applies the extraction principle by removing the complex mechanical clutch device from the torque limiting system and replacing it with a simpler magnetic torque limiting device. The magnetic device uses magnetic field interactions rather than mechanical engagement, thereby reducing mechanical complexity while maintaining component protection functionality. This resolves the contradiction by extracting the problematic mechanical elements while preserving the essential torque limiting function.
Solution Approach 2:
The patent applies mechanics substitution by replacing the mechanical clutch-based torque limiting system with a magnetic torque limiting device. The magnetic device uses electromagnetic or permanent magnet interactions to limit torque without the need for mechanical engagement, wear-prone components, or complex mechanical linkages. This substitution reduces device complexity while improving reliability through a more robust, maintenance-free mechanism.
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 provides greater control over speed and power, optimizes battery usage, and prevents component damage by regulating torque and power delivery, enhancing the reliability and efficiency of surgical procedures.
Implementation Method 1
the magnetic drive train torque limiting device may include a stator, a rotor, and a magnet assembly including a plurality of magnets arranged in an alternating polarity pattern around a circumference of the rotor
Implementation Method 2
it is also known in the prior art to include electrodes in the end effector that can be used to emit/receive RF energy to form a hemostatic line along the cut line
Data Source
AI summary
A surgical cutting and fastening instrument. The instrument comprises an end effector and a shaft connected to the end effector. The shaft comprises a drive train for powering the end effector. The instrument also comprises an electric, DC motor connected to the drive train for powering the drive train. The instrument also comprises a torque-limiting device connected between to an output pole of the motor and an input pole of the drive train.