Asymmetric Screw Drive Design Prevents Reverse Rotation
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Solution Overview
Problem
Existing screw and nut drive designs that prevent loosening often require additional measures and can be prone to corrosion, particularly with tear-off screws, and may not effectively prevent reverse rotation torque transmission.
Innovation Solution
A drive design featuring obliquely extended transition surfaces that, when rotated in one direction, allow torque transmission but prevent it in the reverse direction by producing a force component that disengages the tool, with drive surfaces in radial planes or deviations, and transition surfaces forming wedges or inward/outward surfaces for secure engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional measures are taken to prevent loosening (such as boring or smashing the plug), then security against loosening is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The drive design employs asymmetric transition surfaces that are oblique relative to the drive surfaces. This asymmetry creates a geometric lock where the tool can be inserted and driven in the fastening direction, but cannot be removed or driven in the loosening direction without destruction. The asymmetric geometry inherently prevents loosening without requiring additional security measures.
Solution Approach 2:
The drive design segments the contact surfaces into distinct drive surfaces and transition surfaces with different orientations. The drive surfaces are arranged for torque transmission in the fastening direction, while the transition surfaces are oblique and prevent tool removal. This segmentation allows each surface to perform its specific function independently.
2Reliability
If tear-off screws with predetermined breaking points are used, then security against loosening is improved, but ease of operation and reliability deteriorate due to corrosion and pedantic handling
Solution Approach 1:
Instead of using tear-off screws with breaking points, the invention uses asymmetric drive geometry where the transition surfaces are oblique to prevent tool removal. This provides security against loosening without requiring the screw to be broken off, eliminating corrosion issues at breaking points and simplifying handling procedures.
3Ease of operation
If conventional drive designs are used, then ease of operation is maintained, but reliability against reverse rotation torque transmission deteriorates
Solution Approach 1:
The transition surfaces are designed to be oblique relative to the drive surfaces, creating an asymmetric geometry that allows tool insertion and driving in the fastening direction but prevents tool removal and reverse rotation. The oblique transition surfaces generate forces that press the tool out of the recess when torque is applied in the loosening direction.
Solution Approach 2:
The drive design dynamically responds to the direction of applied torque. When torque is applied in the fastening direction, the drive surfaces transmit the torque effectively. When torque is applied in the loosening direction, the oblique transition surfaces generate an axial force component that dynamically ejects the tool from the recess, preventing reverse rotation.
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 design ensures that screws can only be loosened with difficulty or destroyed, providing secure fastening without additional measures and minimizing corrosion risks, while allowing effective force transmission during driving.
Implementation Method 1
the transition surfaces extend so obliquely that the force applied in the direction of rotation produces a force component that presses the tool out of the recess
Data Source
AI summary
A screwdriver drive design for a screwdriver features an engagement end that is complementary to a fastening element drive design for a fastening element to be screwed. The fastening element drive design includes at least two drive surfaces formed on the fastening element for transmission of a torque suitable for rotation with a tool in a first rotation direction and transition surfaces disposed between these drive surfaces. The transition surfaces form a guide surface for the tool when rotating the tool in the first rotation direction and upon engagement of the tool in the other rotation direction causes an axial outward displacement of the tool, wherein the transition surfaces are formed as outside surfaces, and wherein the outside of the fastening element, outside the transition surfaces and the drive surfaces, lies in a cylindrical jacket forming a recess.