Spur Gear Dose Control Mechanism for Overrun-Free Drug Delivery
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Solution Overview
Problem
Existing fluid delivery devices face challenges in preventing drug overdoses due to component malfunctions, particularly in actuator, electronics, and software, which can lead to intolerable risks for users.
Innovation Solution
An overrun prevention mechanism using spur gears and a plate with pins to control fluid delivery, ensuring a predetermined dose per cycle by limiting rotation to a specific arc path and reversing the actuator direction when the arc path is completed, independent of input direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electronic control systems are used to control fluid delivery, then dose precision can be improved, but system complexity and risk of malfunction increase
Solution Approach 1:
The patent replaces electronic control systems with a purely mechanical overrun prevention mechanism. The mechanism uses a cam surface with a predetermined arc path that physically limits the rotation of the actuator to a specific range. When the actuator reaches the end of the arc path, the cam surface geometry automatically prevents further rotation, eliminating the need for electronic sensors, motors, or control software while maintaining precise dose delivery.
Solution Approach 2:
The mechanical cam surface is designed to automatically prevent overrun without requiring external control systems. The geometry of the cam surface itself provides the control function - as the actuator rotates, the cam surface guides the motion and automatically stops rotation at the predetermined point, making the system self-regulating and eliminating dependency on electronic control components.
2Measurement precision
If electronic control and software are used to prevent overdose, then dose accuracy can be improved, but reliability decreases due to component malfunction risk
Solution Approach 1:
The patent eliminates electronic control systems and software that are prone to malfunction by implementing a passive mechanical constraint. The cam surface geometry physically prevents the actuator from rotating beyond the dose-delivery range, providing inherent overdose protection that does not depend on functional electronics or software logic.
Solution Approach 2:
The cam surface is designed in advance with a predetermined arc path that limits actuator rotation to exactly the range needed for one dose. This pre-engineered geometric constraint ensures that even if the actuator continues rotating, the mechanical structure itself prevents overdose by making it physically impossible to deliver more than the intended dose.
3Reliability
If additional electronic components are added for overdose prevention, then safety can be improved, but device complexity increases
Solution Approach 1:
The patent achieves overdose prevention without adding electronic components by using a cam surface with a predetermined arc path. The mechanical geometry of the cam surface inherently limits actuator rotation to the safe range, providing safety functionality through passive mechanical constraint rather than active electronic control.
Solution Approach 2:
The patent extracts the control function from electronic systems and embeds it directly into the mechanical structure of the cam surface. By taking out the need for electronic sensors, motors, and control circuits, the invention achieves both safety and simplicity through a purely mechanical solution.
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 mechanism ensures accurate and controlled dose delivery by preventing overdosing and maintaining dose accuracy in each cycle, even with actuator malfunctions, without requiring additional electronics, thus reducing user risk and system complexity.
Implementation Method 1
first and second spur gears comprising gear teeth and disposed adjacent to each other to engage a selected number of their corresponding gear teeth
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A dose control and overrun protection mechanism is provided for use in fluid delivery devices such as wearable infusion pumps and medication delivery pens. The mechanism comprises oppositely rotating spur gears with surface features that guide a pin on a plate rotating along a desired arc path (e.g., less than 180 degrees) in alternating directions per delivery cycle of a predetermined dose amount. The surface features are configured to controllably rotate one of the spur gears and output a selected amount or rotation to another component in the power train of a fluid delivery device regardless of direction of actuator input and regardless of whether the actuator rotates beyond the arc path.