Ratcheting Nut-and-Bolt Fastener for Tool-Free Vibration Locking
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Solution Overview
Problem
Conventional nut-and-bolt fasteners require rotational force for assembly, can loosen due to vibration, and necessitate specific tools and multiple lengths, leading to inefficiencies and safety issues.
Innovation Solution
A fastener system featuring a bolt with non-helical teeth and a nut with corresponding ridges that allow unidirectional translation, eliminating the need for rotational force and specific tools, and providing secure locking without the risk of loosening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional helical threads are used, then rotational movement converts to linear movement, but rotational force and specific tools are required
Solution Approach 1:
The patent replaces the helical thread mechanism with a rack-and-pawl mechanism. The bolt has linear rack teeth instead of helical threads, and the nut has corresponding pawl teeth that engage unidirectionally. This substitution eliminates the need for rotational motion and traditional wrenches, allowing simple linear pushing or tapping to achieve fastening.
2Reliability
If conventional nut-and-bolt fasteners are used, then fastening can be achieved, but vibration or rotation may work the nut loose
Solution Approach 1:
The patent employs asymmetric tooth geometry where the pawl teeth on the nut have a inclined face that allows easy engagement in one direction but prevents disengagement in the opposite direction. This asymmetric design creates a mechanical ratchet effect that locks the fastener in place and prevents loosening under vibrational or rotational loads.
3Adaptability or versatility
If different bolt lengths are stocked for different applications, then appropriate fastening length is achieved, but inventory complexity and cost increase
Solution Approach 1:
The patent segments the bolt into a standardized shaft portion and allows the fastening length to be determined by the position where the nut is placed along the shaft. The rack teeth are distributed along the shaft, enabling the nut to engage at various positions. This allows a single standardized bolt design to serve multiple length requirements by simply varying the nut placement position.
4Strength
If rotational torque is applied to tighten conventional fasteners, then secure fastening is achieved, but over-torqueing or under-torqueing can create problems
Solution Approach 1:
The rack-and-pawl mechanism is self-regulating. As the nut is pushed or tapped along the bolt, the pawl teeth gradually engage with the rack teeth, and the mechanical geometry automatically provides the necessary clamping force. The system self-adjusts to the required fastening strength without requiring external torque measurement or control, eliminating over-torqueing or under-torqueing issues.
Data Source
AI summary
A nut-and-bolt fastener is provided. The nut and bolt are configured with a plurality of interlocking teeth that provide unidirectional travel of the nut with respect to the bolt. In particular, the configuration of the teeth arrest separation of the nut from the bolt while permitting the nut to move toward the head of the bolt into a fastened engagement. The teeth are non-helical and arranged concentrically around the longitudinal axis in evenly-spaced steps or segments along the longitudinal axis and around the shaft of the bolt and bore of the nut. Integral winged washers are provided on the bolt head as well as on the nut. Variations with different rake angles of the teeth as well as an expandable nut are also provided.