Bone Screwdriver Expander Spring Mechanism
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Solution Overview
Problem
Existing screwdrivers for bone screws require complex mechanisms for advancing and retracting the expander element, making the connection and disconnection process cumbersome.
Innovation Solution
Incorporating an elastic spring element to pretension the expander element, allowing it to automatically move into a clamping position for secure engagement with the bone screw, and retracting it simply by releasing the spring, with features like a stop for limiting movement and a transmission member connected to the handle for easy operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex mechanism is used to advance and retract the expander element, then the connection and disconnection can be controlled, but the device complexity increases and ease of operation deteriorates
Solution Approach 1:
The spring element automatically advances the expander element into the bone screw without requiring complex actuation mechanisms. The system serves itself by using elastic energy stored in the spring to perform the connection action, eliminating the need for complex mechanical advantage systems or multiple actuating components.
Solution Approach 2:
The complex mechanism for advancing the expander element is extracted and replaced with a simple spring-loaded system. Only the essential function of connection is retained through the spring and expander element, while unnecessary mechanical complexity is removed.
2Reliability
If a complex mechanism is used to advance and retract the expander element, then the connection can be secured, but the ease of operation deteriorates
Solution Approach 1:
The spring element automatically performs the connection action by advancing the expander element into the bone screw. The operator simply needs to position the shaft, and the spring automatically secures the connection without requiring complex manual manipulation or multiple steps.
Solution Approach 2:
The spring element is pre-loaded with elastic energy before use. This preliminary energy storage allows the expander element to be rapidly and reliably advanced into the bone screw with minimal operator input, improving ease of operation while maintaining connection security.
3Productivity
If the expander element is allowed to advance freely, then the connection is established quickly, but mechanical stress is applied to the shaft
Solution Approach 1:
The stop element is positioned in advance to limit the advancing movement of the expander element. This preliminary restriction prevents the expander from traveling too far and applying excessive mechanical stress to the shaft, while still allowing sufficient advancement to establish a secure connection.
Solution Approach 2:
The stop element acts as an intermediary between the spring force and the shaft. It mediates the force transmission by providing a controlled stopping point that allows the expander element to advance enough to secure the connection without transmitting excessive force to the shaft.
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 a simple and secure connection and disconnection process between the screwdriver and bone screw, enhancing user convenience and ensuring a positive lock without mechanical stress on the shaft.
Implementation Method 1
an elastic spring element (16) is arranged in a ring space (15) between the sleeve (13) and the shaft (3), which pretensions the at least one expander element (11, 21, 31) in the direction towards the free end (4) of the shaft (3)
Data Source
AI summary
In a screwdriver for bone screws, having a handle and rotationally fixedly held thereon a shaft, the free end of which has a non-circular cross section and is insertable in a positively locked manner in a non-circular receiving opening in the head of a bone screw, at least one expander element being mounted so as to be displaceable in the longitudinal direction in the shaft and so as to slide, when displaced in the longitudinal direction, along a slide surface in the area of the free end of the shaft in such a way that it projects laterally over the contour of the shaft, in order to simplify the actuation of the at least one expander element, it is proposed that the at least one expander element be pretensioned by an elastic spring element in the direction towards the free end of the shaft and be retractable against the action of the spring element in the shaft until it no longer projects laterally over the contour of the shaft.