Gear Assembly Force Transmission in Injection Device
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Solution Overview
Problem
Existing injection devices require excessive force to deliver high viscosity substances due to increased viscosity and thinner needle gauges, leading to user fatigue during prolonged operations.
Innovation Solution
An injection device with a drive mechanism comprising a gear assembly that transmits force from a drive rod to a plunger rod, allowing for reduced input force required to expel viscous substances, featuring a compact design with a finger grip-mounted drive mechanism and a return spring for ergonomic operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high viscosity substances are injected through thin gauge needles, then the injection capability is maintained, but the force required for injection increases excessively
Solution Approach 1:
The injection device is divided into separate functional modules: a drive mechanism with drive rod, a gear assembly for force transmission, and a plunger mechanism. This segmentation allows the force generation and application to be optimized independently, reducing the input force needed while maintaining injection capability.
Solution Approach 2:
A gear assembly acts as an intermediary between the drive rod and the plunger. The gear assembly transmits and amplifies the force applied to the drive rod, converting it into the necessary plunger force with reduced input effort from the user.
2Ease of operation
If a gear assembly is added to reduce input force, then the ease of operation improves, but the device complexity increases
Solution Approach 1:
The drive mechanism components (drive rod, gear assembly, plunger rod) are merged into a compact integrated unit that fits within the finger grip. This combining of functions reduces the overall device complexity despite adding the gear assembly, as the components share space and structural support.
Solution Approach 2:
The drive mechanism components are nested within each other: the gear assembly is positioned between the drive rod and plunger rod, with all components fitting within the confines of the finger grip housing. This nesting minimizes the external dimensions and overall complexity of the device.
3Volume of moving object
If the drive mechanism is made compact for finger grip, then the device portability improves, but the force transmission efficiency may be compromised
Solution Approach 1:
The gear assembly utilizes rotational motion in a different dimension to achieve linear force transmission. By converting the rotational movement of the gear teeth into linear plunger movement, the design achieves effective force transmission within the limited space of the finger grip without compromising mechanical efficiency.
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
Facilitates easy and ergonomic operation by reducing the force needed to inject viscous substances, allowing for efficient delivery without user fatigue and enabling a compact, reusable design adaptable to varying viscosities and needle sizes.
Implementation Method 1
a gear assembly (20) arranged such that an axial movement of the drive rod (11) generates an axial movement of the plunger rod (12)
Implementation Method 2
The gear assembly allows for a force transmission between the drive rod and the plunger rod, such that a force applied to the drive rod is transmitted and reinforced by the gear assembly to the plunger rod
Implementation Method 3
a return spring (35) arranged to force the drive rod (11) towards the idle position
Data Source
Figure 1a
Figure 1b
Figure 2a
AI summary
The present invention relates to an injection device comprising a drive mechanism (10), the drive mechanism (10) comprising a drive rod (11) being axially moveable, a plunger rod (12) being axially moveable, and a gear assembly (20). The gear assembly (20) is arranged such that an axial movement of the drive rod (11) generates an axial movement of the plunger rod (12). This allows for a force transmission between the drive rod (11) and the plunger rod (12), facilitating the expelling of viscous substances from the injection device.