Injection Button Pivot Bearing Friction Reduction
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Solution Overview
Problem
Existing injection devices require users to apply significant force to overcome friction between the push button and the driving member during the injection process, making it difficult to administer a dose due to relative rotation and resulting frictional forces.
Innovation Solution
A push button connection with a pivot bearing and radial bearings is designed to minimize friction by optimizing the surface area and radius of interaction, using materials with low internal friction and surface treatments, and incorporating a snap-on assembly mechanism to secure the push button in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the push button and driving part are connected with direct contact, then the connection is simple, but the friction between relatively rotatable parts increases the force required for injection
Solution Approach 1:
A pivot bearing is introduced as an intermediary element between the push button and the driving part. The pivot bearing includes a pivot point on the push button that contacts a bearing surface on the driving part, creating a defined rotation axis that minimizes friction during relative rotation while maintaining structural simplicity
2Reliability
If the surface area of interaction between push button and driving part is large, then the connection is stable, but the friction force increases requiring more user effort
Solution Approach 1:
Instead of a large contact area, the invention concentrates the interaction at a specific local point - the pivot point. This point contact provides sufficient rotational stability and connection reliability while minimizing the contact area to reduce friction forces during injection
3Strength
If the radius of the friction force is large, then the structural strength is sufficient, but the moment arm for friction increases the required injection force
Solution Approach 1:
The pivot bearing creates a point contact with a very small effective radius, essentially minimizing the moment arm for friction forces. The curved pivot point allows rotation while keeping the friction moment (friction force × radius) to a minimum, reducing the effort required for injection
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
This design reduces the force required for injection by minimizing frictional resistance, allowing for easier and more efficient dose administration while maintaining structural integrity and preventing accidental disassembly.
Implementation Method 1
the friction occurring between these relatively rotatable parts contributes to the force a user needs to apply In order to push back the bushing and the scale drum
Data Source
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AI summary
A push button connection for an injection device comprising a push button (10) and a driving part (20). The two parts of the push button connection are mounted to each other and is relatively rotatable to each other. In order to minimize the friction occurring between the push button and the driving part when relatively rotated forces are transmitted via a pivot bearing (18, 22). In order also to minimize the effect of forces appearing dislocated from the center line a number of radial bearings (13, 23; 14, 25) having a little friction diameter is provided.