Injection Speed Adjustment in Spring-Driven Pen Injectors
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Solution Overview
Problem
Existing injection devices lack a simple and reliable mechanism for adjusting injection speed, which is crucial for accommodating varying needle diameters and liquid viscosities, often resulting in inefficient or uncomfortable operation.
Innovation Solution
An injection device with a movable and non-rotatable first component within the housing, allowing for separate adjustments of injection speed and liquid ejection, featuring a latching device and a setting spring to dynamically control the energy required for injection, enabling stepless speed adjustment and ergonomic handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a friction element is used to control injection speed, then injection speed can be adjusted, but the device structure becomes complex and space-consuming
Solution Approach 1:
The patent extracts the speed control function from a separate friction element mechanism and integrates it into the existing latching device structure. The latching device's radial movement of locking elements creates variable friction against the drive part's circumferential surface, providing speed control without requiring additional dedicated friction control components.
Solution Approach 2:
The latching device is given dual functionality: it simultaneously provides the locking function (securing the drive part axially) and the speed control function (controlling injection speed through variable friction). This eliminates the need for separate friction elements and reduces overall device complexity.
2Speed
If the drive part is held stationary axially, then injection speed can be controlled, but the structure becomes more complex
Solution Approach 1:
The patent merges the axial positioning function and the speed control function into a single integrated mechanism. The latching device simultaneously performs axial securing of the drive part and speed control through its locking elements' interaction with the drive part's circumferential surface, eliminating the need for separate stationary holding structures.
Solution Approach 2:
Instead of using a separate stationary element to hold the drive part axially while another mechanism controls speed, the patent inverts the approach by making the latching device itself perform both functions. The locking elements' radial positioning simultaneously achieves axial securing and variable friction-based speed control.
3Speed
If a latching device with locking elements is used, then injection speed can be adjusted by changing radial position, but the device requires more space
Solution Approach 1:
The locking elements are nested within the latching device structure, with their radial movement occurring within the existing housing boundaries. The drive part rotates within the housing while the locking elements engage with its circumferential surface, utilizing the existing spatial arrangement to provide speed control without requiring additional external space.
Solution Approach 2:
The patent controls injection speed by moving locking elements in the radial direction (perpendicular to the rotation axis), rather than requiring axial or circumferential displacement. This radial dimension allows compact speed adjustment within the existing cylindrical housing volume.
4Device complexity
If the first component is guided in a movable and non-rotatable manner, then structure is simplified, but speed adjustment range is limited
Solution Approach 1:
The patent makes the latching device dynamic by allowing radial movement of the locking elements during rotation. The locking elements can move radially inward and outward relative to the drive part, enabling continuous speed adjustment from zero to maximum injection speed while maintaining the simple guided structure of the first component.
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 device provides precise and comfortable injection speed control, ensuring reliable operation even with high-viscosity liquids and thin needles, with the ability to dynamically adjust speed during use, enhancing user experience and operational efficiency.
Implementation Method 1
The adjustment device advantageously includes an operating element which is pretensioned by an adjustment spring. The setting spring counteracts a movement of the operating element in the direction of increasing the injection speed.
Implementation Method 2
The adjustment device advantageously includes an operating element which is pretensioned by an adjustment spring
Implementation Method 3
Provision can also be made for the setting device to influence a frictional force acting between the first component and the second component in addition to a latching device
Data Source
Figure 1~2
Figure 3~4
Figure 5~11
AI summary
An injection apparatus (1) for automatically expelling a dose of injection liquid from a container (5) has a housing (2) having a central longitudinal axis (50) and a first component and a second component. The first component and the second component move relative to each other when injection liquid is expelled. A spring (9) is provided which is tensioned as a dose of injection liquid to be injected is set. When the injection liquid is expelled, the force accumulated in the spring at least partially released. In order to set the injection speed, the injection apparatus (1) has a setting device (41) which influences the force which is necessary for moving the second component relative to the first component.