Motor Control for Liquid Medicine Administration Device
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Solution Overview
Problem
Conventional liquid medicine administration devices require high driving force in the initial sliding section, leading to increased motor and battery size, resulting in a larger device.
Innovation Solution
A liquid medicine administration device with a control unit that controls the motor's rotational speed, implementing a program to repeat one cycle of continuous rotation and stop during the initial sliding section, reducing the driving force by advancing the gasket at intervals, and switching to higher speed in the normal sliding section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the motor is increased in size to provide high driving force in the initial sliding section, then the driving force is sufficient, but the device size increases
Solution Approach 1:
The motor operates in periodic cycles consisting of rotation periods and stop periods. During rotation, the gasket advances; during stop periods, adhesion is released. This periodic operation allows the use of a smaller motor compared to continuous high-force operation, while still achieving the necessary driving force during rotation phases.
Solution Approach 2:
The stop period serves as a preliminary action that releases adhesion before the next rotation. By allowing the gasket to release adhesion during stop periods, the subsequent rotation requires less force to overcome adhesion, enabling the use of a smaller motor while maintaining effective driving force during advancement.
2Speed
If the motor rotates continuously to advance the gasket quickly, then the administration rate is high, but the adhesion releases poorly and sliding resistance increases
Solution Approach 1:
The motor operates in periodic cycles with rotation periods for advancement and stop periods for adhesion release. This periodic action ensures that the gasket is advanced at appropriate speeds while allowing sufficient time during stop periods for adhesion to release, preventing excessive sliding resistance and ensuring reliable operation.
3Reliability
If the stop time in each cycle is increased to improve adhesion release, then adhesion releases better, but the total operation time increases
Solution Approach 1:
The motor operates in periodic cycles optimized to balance adhesion release with operation time. The stop periods are sufficient to release adhesion but kept as short as possible to minimize total operation time. This periodic action achieves reliable adhesion release while maintaining efficient overall operation.
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
The solution effectively reduces the driving force required in the initial sliding section, preventing size increases and maintaining a desired administration rate while minimizing power consumption.
Implementation Method 1
a liquid lubricant applied to an inner peripheral surface of the cylinder or an outer peripheral surface of the gasket
Data Source
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AI summary
A liquid medicine administration device (10) includes: a cylinder (12) filled with a liquid medicine (M), a gasket (34) placed inside the cylinder (12); an advancing mechanism (36) configured to advance the gasket (34) in a distal direction; a drive mechanism (42) including a motor (40) that is configured to drive the advancing mechanism (36); a battery (26) configured to supply power to the motor (40); and a control unit (28) configured to control a rotational speed of the motor (40). In a first movement section that is an initial sliding section included in an advancing movement of the gasket (34) in the cylinder (12), one cycle including one continuous rotation and one continuous stop of the motor (40) is repeated two or more times.