Self-locking Bolt Nut Assembly with Elastic Washer
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Solution Overview
Problem
Conventional bolt-nut assemblies face issues with loosening due to external vibrations or shocks, and existing self-locking mechanisms are inadequate, particularly when using soft materials, as they fail to maintain torque consistency and are prone to wear, making them unsuitable for harsh environments.
Innovation Solution
A self-locking bolt-nut assembly featuring a bolt with an external thread and an insertion guide groove, a nut with stop protrusions, and a washer with elastic protrusions that elastically bend and lock into place, providing consistent torque and easy replacement of the washer for re-tightening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the washer is made of soft material (rubber, plastic), then the one-way stop protrusions can pass over each other more easily, but the washer cannot withstand high bolt coupling torque and compression force, and cannot withstand severe environments like high temperature and high pressure
Solution Approach 1:
The washer is segmented into multiple elastic protrusions that can independently deform and recover. This segmentation allows the washer to maintain flexibility for easy tightening while distributing the load across multiple contact points, thereby withstanding high torque and compression forces without requiring the entire washer to be made of soft material.
Solution Approach 2:
The washer utilizes elastic deformation as its working principle, changing the physical state of the material during operation. The elastic protrusions deform under compression and torque during tightening, then recover to maintain continuous contact and locking force. This parameter change allows the washer to adapt to varying load conditions and environmental temperatures while maintaining both ease of operation and strength.
2Reliability
If the nut is forcibly tightened onto the bolt body, then the nut can be secured, but the one-way stop protrusions may be worn or damaged (broken), thus malfunctioning
Solution Approach 1:
The elastic protrusions are designed to deform elastically under load, providing a cushioning effect before the one-way stop protrusions engage. This beforehand cushioning absorbs the shock and stress of forced tightening, preventing direct impact damage to the protrusions and ensuring they are not worn or broken during the tightening process.
Solution Approach 2:
The elastic protrusions change their physical state from rigid to deformed under load, allowing them to accommodate forced tightening without transmitting excessive stress to the one-way stop protrusions. This parameter change protects the protrusions from wear and damage while maintaining locking reliability.
3Reliability
If the one-way stop protrusions are formed on the washer and nut, then self-locking function is provided, but the compression force between the protrusions largely varies while passing over each other, causing tightening torque to be non-constant
Solution Approach 1:
The washer is divided into multiple elastic protrusions that engage with corresponding features on the nut in sequence. This segmentation distributes the engagement process across multiple contact points, smoothing out the variation in compression force and resulting in more consistent tightening torque throughout the fastening process.
Solution Approach 2:
The elastic protrusions are designed to dynamically adapt their deformation based on the engagement stage. During initial engagement, they deform more to accommodate alignment variations, then gradually reduce deformation as proper contact is established. This dynamic behavior maintains relatively constant compression force and tightening torque throughout the fastening process.
4Strength
If the washer is made of hard material, then it can withstand high torque and compression force, but the one-way stop protrusions cannot pass over each other
Solution Approach 1:
The washer is segmented into multiple discrete elastic protrusions rather than a continuous hard structure. This segmentation allows individual protrusions to deform elastically during tightening while the overall washer structure maintains high strength. The protrusions can pass over each other and engage with the nut features, providing both ease of operation and structural strength.
Solution Approach 2:
The washer embodies a composite structure combining elastic material properties with a rigid geometric form. The elastic protrusions provide the necessary flexibility for engagement and passing over each other, while the overall washer structure maintains sufficient strength to withstand high torque and compression forces. This composite approach resolves the contradiction between hardness and flexibility.
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 solution ensures the nut remains securely fastened by elastic locking, maintains consistent torque, and allows for easy loosening and re-tightening by replacing the washer, addressing the limitations of existing technologies in harsh environments.
Implementation Method 1
a plurality of elastic protrusions (320a, 320b) provided on a surface of the washer (300a, 300b) that comes into contact with the nut (200a, 200b), the elastic protrusions (320a, 320b) being arranged in a circumferential direction at regular intervals, whereby when the nut (200a, 200b) which has been in contact with the washer (300a, 300b) is tightened, the elastic protrusions (320a, 320b) are elastically bent while passing over first surfaces of corresponding stop protrusions (210a, 210b), and then are returned to original states thereof by elastic force so that elastic protrusions (320a, 320b) are locked to second surfaces of the stop protrusions (210a, 210b)
Data Source
AI summary
The present invention relates to a self-locking bolt-nut assembly including a bolt; a nut tightened on the bolt; and a washer provided between the bolt and the nut, wherein the nut has a counterbore being formed in the nut, and has a plurality of stop protrusions formed on the inner surface of the circumferential sidewall of the counterbored portion of the nut, the stop protrusions being arranged in a circumferential direction at regular intervals, the washer including the rotation-preventive protrusion protruded on inner circumference of the washer towards the center thereof, the rotation-preventive protrusion being inserted into the insertion guide groove; and a plurality of elastic protrusions which is protruded on outer circumference of the washer, being inclined in the direction where the nut is turned to tighten it.