Exhaust Module Sliding Fastening for Thermal Expansion
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Solution Overview
Problem
The challenge of securely fastening an exhaust module on its support in a multi-cylinder internal combustion engine, particularly in V-configuration, while allowing for thermal expansion without subjecting the fastening components to excessive stress, is unresolved due to the significant temperature difference between the hot exhaust module and the cooler support, leading to potential loosening and fatigue of fastening bolts under engine vibrations.
Innovation Solution
A method involving a sliding connection between the exhaust module and its support, utilizing positioning means such as pin-like members and blind openings, combined with low-friction surfaces or coatings to facilitate thermal movement and reduce frictional stress, allowing the exhaust module to expand freely while maintaining secure fastening through strategically positioned fastening bolts and shims.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the exhaust module is tightly fastened to the support using conventional fastening bolts, then the fastening strength is improved, but the thermal expansion of the exhaust module causes excessive stress on the fastening components leading to fatigue and loosening
Solution Approach 1:
The fastening system transitions from a static rigid connection to a dynamic system that accommodates thermal movement. The exhaust module is designed to slide longitudinally on the support within controlled limits, allowing the connection to adapt to thermal expansion while maintaining secure fastening through friction and positioning means.
Solution Approach 2:
The friction coefficient between the exhaust module and support is modified by applying low-friction coatings (such as Teflon) to specific surfaces. This parameter change reduces the frictional stress on fastening components while maintaining sufficient holding force, allowing the system to withstand thermal expansion without excessive stress.
2Reliability
If the exhaust module is allowed to move freely to accommodate thermal expansion, then the stress on fastening components is reduced, but the exhaust module may become loose or misaligned under external loads and vibrations
Solution Approach 1:
The fastening system is segmented into multiple functional elements: sliding surfaces for thermal movement accommodation, positioning means (pin-like members and blind openings) for alignment, and fastening bolts for securing. This segmentation allows each element to perform its specific function while contributing to overall system reliability.
Solution Approach 2:
Positioning means consisting of pin-like members and matching blind openings act as intermediaries between the exhaust module and support. These positioning elements guide the exhaust module during installation and maintain proper alignment while allowing controlled longitudinal sliding, preventing misalignment under external loads and vibrations.
3Ease of operation
If low-friction surfaces are applied to reduce frictional stress, then the thermal expansion is accommodated more easily, but the complexity of manufacturing and assembly increases
Solution Approach 1:
Low-friction coatings are applied selectively to specific local areas (sliding surfaces) rather than the entire exhaust module or support. This localized application reduces manufacturing complexity while still providing the necessary low-friction properties for thermal expansion accommodation. The coatings are applied only to the foot surfaces and support contact areas where sliding occurs.
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
This solution effectively manages thermal expansion and external loads, ensuring the exhaust module remains securely fastened while minimizing stress on fastening components, allowing for reliable operation under varying engine conditions without risk of loosening due to thermal expansion and vibrations.
Implementation Method 1
providing low-friction means between the feet and the support
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The present invention relates to a method of and a means for fastening an exhaust module (14) of a multi-cylinder internal combustion engine to its support (26) such that the mechanical stresses caused by the thermal expansion of the exhaust module to its feet (24) and the support (26) are avoided by arranging the feet (24) of the exhaust 5 module (14) slide on the support surface (28).