Flexible Vibration Absorbing Tube With Variable Diameter Interlock
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Solution Overview
Problem
Conventional flexible tubes in vehicle exhaust systems suffer from increased size and flow resistance due to 'coupling steps' that expand the exhaust-gas passage, failing to effectively reduce exhaust noise and back pressure.
Innovation Solution
A flexible tube design with a cylindrical bellows tube and interlock tube, where the interlock tube's fixing end portions have a larger diameter than the central portion, allowing the joint pipes' extension portions to fit without creating 'coupling steps, reducing the external diameter of the bellows tube and maintaining the internal passage size, thus minimizing flow resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the interlock tube has a constant diameter, then the joint pipes can be easily fitted, but coupling steps are formed that expand the exhaust-gas passage and increase the flexible tube size
Solution Approach 1:
The interlock tube is designed with varying diameter along its length: the fixing end portions have a larger diameter to facilitate fitting of joint pipes, while the central portion has a smaller diameter to reduce overall size. This local differentiation of dimensions allows the tube to serve multiple functions in different sections.
Solution Approach 2:
Instead of making the entire interlock tube large to accommodate joint pipes, the invention inverts the approach by making only the necessary portions (fixing ends) larger while keeping the central portion smaller, thereby eliminating the coupling step problem.
2Ease of operation
If the coupling step expands the exhaust-gas passage, then the joint pipes can be connected, but flow resistance increases and exhaust noise is not effectively reduced
Solution Approach 1:
The diameter variation is localized only to the fixing end portions where connection is needed, while the central passage-maintaining portion keeps a consistent, optimized diameter to minimize flow resistance and prevent energy loss.
3Ease of manufacture
If the bellows tube outer diameter is expanded to accommodate the interlock tube, then the interlock tube can be fitted, but the flexible tube becomes larger in size
Solution Approach 1:
The bellows tube is designed with localized diameter variations: the outer diameters at positions corresponding to the interlock tube's fixing end portions are expanded to accommodate the larger diameter sections, while the central portion maintains a smaller, optimized diameter.
4Productivity
If the exhaust gas flows through the exhaust-gas passage with coupling steps, then the gas can pass through, but turbulences of flow are created that increase flow resistance
Solution Approach 1:
The passage design maintains smooth, continuous diameter in the central portion where exhaust gas flows, eliminating coupling steps and turbulence-generating discontinuities, while localized diameter changes are confined to the fixing end portions for connection purposes.
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 allows for a smaller flexible tube size without narrowing the exhaust-gas passage, reducing flow resistance and preserving vibration absorption functionality.
Implementation Method 1
a flexible tube serving as a vibration-absorbing pipe connected to the exhaust system of an engine mainly for vehicles or the like to absorb the vibrations from the engine
Implementation Method 2
a cylindrical bellows tube; a cylindrical interlock tube placed inside the bellows tube; the bellows tube includes a bellows portion in which ridge portions and valley portions are alternately formed
Data Source
AI summary
A flexible tube includes a bellows tube, an interlock tube placed inside the bellows tube, and upstream-side and downstream-side joint pipes coupled to opposite ends of the bellows tube. Diameters of fixing end portions located at opposite ends of the interlock tube are made larger than a diameter at a middle portion of the interlock tube, extension portions of the upstream-side and downstream-side joint pipes are fitted and fixed to inner peripheral surfaces of the fixing end portions of the interlock tube, and a depth of each of valley portions of a bellows portion of the bellows tube located over the fixing end portions is smaller than a depth of other valley portions of the bellows portion. Accordingly, it is possible to achieve the downsizing of the flexible tube that is connected to an exhaust system being continuous with an engine to dampen vibrations in the axial direction of the exhaust system.