Stepped Nut Flange Fastening for Plastic-Metal Joints
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Solution Overview
Problem
Existing flange fastening structures in internal-combustion engines face challenges in securely fastening plastic and metal components without causing deformation or compromising sealing and air intake accuracy, as they lack effective mechanisms to manage fastening forces and prevent excessive tightening loads.
Innovation Solution
A flange fastening structure that includes a metal first flange, a plastic second flange, and stepped nuts with raised plastic portions, where the stepped nuts have large and small-diameter portions, and metal collars or stepped bolts, which limit fastening positions and distribute forces to prevent deformation and ensure secure sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional fastening structures are used to secure plastic and metal flanges, then the flanges can be fastened together, but the plastic components deform due to excessive tightening loads
Solution Approach 1:
A plastic insert with a recessed portion is introduced as an intermediary component between the bolt/nut assembly and the plastic flange. This insert acts as a mediator that distributes the fastening load over a larger area, preventing excessive stress concentration that would cause deformation of the plastic flange while still achieving secure fastening.
Solution Approach 2:
The plastic insert features a recessed portion with specific geometric characteristics (depth, diameter) that are optimized for the local stress distribution requirements. The recessed portion is designed with dimensions that match the bolt/nut geometry to ensure proper load distribution exactly where needed, rather than uniformly across the entire flange.
2Reliability
If tight fastening is applied to ensure secure connection, then the flanges are securely fastened, but sealing integrity is compromised due to deformation
Solution Approach 1:
The plastic insert serves as a protective intermediary between the fastening mechanism and the sealing surface of the plastic flange. By absorbing and distributing the fastening forces, it prevents deformation of the sealing surface, thereby maintaining sealing integrity while still achieving reliable mechanical connection.
3Reliability
If excessive fastening force is applied to prevent loosening, then the fastening is secure, but air intake accuracy deteriorates due to component deformation
Solution Approach 1:
The plastic insert acts as a load-distributing intermediary that enables secure fastening without transmitting excessive localized stresses to the plastic flange. This prevents deformation of the flange structure that would otherwise affect air intake passage geometry and flow characteristics, maintaining air intake accuracy.
4Device complexity
If simple fastening structures are used, then device complexity is reduced, but the ability to manage fastening forces and prevent deformation is insufficient
Solution Approach 1:
The fastening system is segmented into distinct functional components: the bolt/nut assembly for applying fastening force, and the plastic insert with recessed portion for distributing that force. This segmentation allows each component to be optimized for its specific function while keeping the overall structure relatively simple and easy to manufacture.
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 structure effectively prevents deformation of plastic components, maintains sealing integrity, and enhances the accuracy of air intake control by managing fastening forces and ensuring reliable fastening of flanges, thereby improving assembly efficiency and reducing the risk of component damage.
Implementation Method 1
A height of the at least one raised portion is set such that the at least one raised portion pressed with the large-diameter portion is deformed by a predetermined amount
Implementation Method 2
the at least one raised portion pressed with the large-diameter portion is deformed by a predetermined amount
Data Source
AI summary
A flange fastening structure includes a first flange made of metal and a second flange made of plastic. Stepped nuts are provided in the second flange and each have a large-diameter portion and a small-diameter portion. The second flange has at least one raised portion on a surface of the second flange facing the large-diameter portion. The at least one raised portion is made of plastic. A height of the at least one raised portion is set such that the at least one raised portion pressed with the large-diameter portion is deformed when the first flange and the second flange are fastened together with bolts and the nuts. The small-diameter portion of each of the nuts contacts the first flange to limit fastening positions of the nuts and the bolts when the first flange and the second flange are fastened together with the bolts and the nuts.