Infusion Pump Stepper Motor Worm Drive Control
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Solution Overview
Problem
Existing infusion pumps lack precise control over the administration of fluid doses, particularly in ambulatory settings, where small, adjustable doses are necessary, and there is a need for improved accuracy and safety to prevent uncontrolled fluid release.
Innovation Solution
An infusion pump with a worm and worm-wheel drive mechanism controlled by a stepper motor, combined with a brake mechanism and electronic control system, allowing for precise control of the plunger movement and fluid expulsion rate, and featuring a brake mechanism to prevent uncontrolled movement in case of component failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a worm and worm-wheel drive mechanism controlled by a stepper motor is used to control plunger movement, then precise control over fluid dose administration is achieved, but the device complexity increases
Solution Approach 1:
The patent replaces traditional mechanical drive mechanisms with a worm and worm-wheel drive controlled by a stepper motor. This substitution enables precise control of plunger movement through electronic control of the stepper motor, directly achieving accurate dose administration while managing the complexity through integrated motor-control systems.
2Reliability
If a brake mechanism is added to prevent uncontrolled plunger movement, then safety is improved, but the device complexity increases
Solution Approach 1:
The brake mechanism is designed to prevent uncontrolled plunger movement by applying a braking force that counteracts any unintended motion. This preliminary anti-action ensures that even if the drive mechanism fails or malfunctions, the plunger cannot move uncontrollably, thereby maintaining safety without requiring complex additional control systems.
3Use of energy by moving object
If the worm and worm-wheel drive is designed to be close to backdrive balance, then the motor size and current consumption are reduced, but the control precision becomes more sensitive to torque variations
Solution Approach 1:
The patent optimizes the worm and worm-wheel drive parameters to achieve a state close to backdrive balance. This parameter optimization reduces the torque required to drive the mechanism, thereby reducing motor size and current consumption. The design carefully balances the gear ratio and friction characteristics to maintain adequate control stability while minimizing energy requirements.
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 enables precise and adjustable dose administration, reduces the size and weight of the pump, extends battery life, and ensures safety by preventing uncontrolled fluid release, making it suitable for long-term ambulatory use.
Implementation Method 1
a retaining member operably connected to a stepper motor via a worm and worm-wheel drive and which acts on the plunger to control or prevent travel of the plunger
Implementation Method 2
a brake mechanism comprising a brake member for engaging with a wall of the receptacle to prevent or inhibit uncontrolled movement of the plunger
Implementation Method 3
The propulsion mechanism which urges the plunger or piston towards the receptacle outlet may comprise a compression spring
Data Source
AI summary
An infusion pump for administering controlled doses of a fluid comprises: a receptacle (2) for storing the fluid (6), the receptacle having an outlet (8) for dispensing the fluid; a plunger (12); a propulsion mechanism (14) which urges the plunger (12) in a direction to pressurise the fluid (6) and dispense it through the outlet (8); and a retaining member (16) which acts on the plunger (12) to control or prevent travel of the plunger (12); characterised in that the retaining member (16) is operably connected to a stepper motor (24) via a worm (22) and worm-wheel (18) drive.