Pen Applicator Screw Locking Mechanism
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Solution Overview
Problem
Existing pens with non-rotationally symmetrical applicators face challenges in securing the applicator to the barrel due to inconsistent frictional resistance, which can change over time and with environmental influences, leading to difficulties in adjustment and reliability issues.
Innovation Solution
A screw connection is implemented for reliable locking of the applicator in both axial and rotational directions, accompanied by a torque-limited actuator and latching device to ensure secure attachment and prevent unintentional loosening, with unsymmetrical contours and a flexible design for easy production and user handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If frictional resistance is used to hold the applicator in the barrel, then the applicator can be adjusted rotationally, but the frictional force is difficult to control and may change over time due to ageing and environmental influences
Solution Approach 1:
The patent changes the parameter of the connection mechanism from friction-based to screw-thread-based. The screw connection provides a reliable, controllable holding force through threaded engagement, eliminating the instability of frictional resistance that changes with ageing and temperature. The screw connection maintains constant mechanical engagement regardless of environmental conditions.
Solution Approach 2:
The patent replaces the friction-based mechanical holding system with a screw-thread mechanical system. The screw connection uses threaded geometry to convert rotational motion into axial clamping force, providing predictable and stable holding characteristics that are not dependent on friction coefficient variations.
2Reliability
If elevations and recesses for bayonet closure are provided on the applicator and barrel, then the applicator is secured in the barrel, but the closure is expensive and complicated to produce and handle
Solution Approach 1:
The patent extracts the complex bayonet closure elevations and recesses, replacing them with a simpler screw connection. The screw thread geometry provides the necessary securing function without requiring complicated molded features, reducing manufacturing complexity and cost while maintaining reliable applicator attachment.
Solution Approach 2:
Instead of using protrusions and recesses that interlock (bayonet closure), the patent uses a threaded screw connection that engages through complementary helical surfaces. This inverted approach to mechanical engagement simplifies the structure while providing secure, multi-directional locking capability.
3Ease of manufacture
If a screw connection is used to lock the applicator, then reliable and simple production is ensured, but torque may damage parts if too great force is applied
Solution Approach 1:
The screw connection is designed with self-limiting torque characteristics through its thread geometry and engagement depth. The natural mechanical properties of the screw-thread interaction provide inherent torque limitation, preventing excessive force from damaging components during assembly while maintaining simple production processes.
4Strength
If unsymmetrical contours are provided for torque limitation, then the torque that may be applied is limited, but the contours must be precisely manufactured
Solution Approach 1:
The patent employs unsymmetrical contour features on the screw connection components to limit applied torque. The asymmetric geometry creates natural mechanical stops and varying engagement characteristics that prevent excessive torque application. These contours are designed with tolerances that accommodate normal manufacturing variations while maintaining their torque-limiting function.
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 screw connection provides a reliable and environmentally stable attachment of the applicator, preventing unintentional loosening and allowing for precise rotational positioning, thus simplifying production and handling while maintaining reliability across varying conditions.
Implementation Method 1
a screw connection for locking the applicator in the axial direction and/or in the direction of rotation
Implementation Method 2
the actuator has a first contour, which works together with a second contour of the screw connection that matches the first contour when actuating the screw connection and the first and/or the second contour is/are unsymmetrical in such a way that the torque that may be applied with the actuator is limited
Data Source
AI summary
The invention refers to a pen with a barrel and an applicator, in which the barrel has a depression for gripping and the applicator has a contour that is not rotationally symmetrical with reference to a longitudinal axis of the pen and may be adjusted around the longitudinal axis in the direction of rotation with reference to the depression for gripping. According to the invention a screw connection is provided for locking the applicator in the axial direction and/or in the direction of rotation.