Spring-Supported Securing Nut for Exhaust Manifold Thermal Movement
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Solution Overview
Problem
Existing fastening arrangements for exhaust manifolds in internal combustion engines face issues with temperature fluctuations causing the manifold to slide, leading to bending moments on threaded bolts, potential loosening of nuts, and leaks due to inadequate support and scalability of spring forces.
Innovation Solution
A fastening nut design featuring separate, elastically preloaded spring parts that provide indirect or direct axial support to the exhaust manifold, allowing for adjustable spring force and reduced load on the threaded bolt, with braking torque means to enhance loosening torque, and no requirement for large openings in the exhaust manifold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid fastening nut is used to secure the exhaust manifold, then the clamping force is strong, but the exhaust manifold cannot accommodate thermal expansion and sliding, leading to bolt deformation and nut loosening
Solution Approach 1:
The patent introduces a spring section that can elastically deform axially, changing the mechanical properties from rigid to compliant. This allows the fastening system to accommodate thermal expansion and sliding of the exhaust manifold while maintaining adequate clamping force through elastic recovery of the spring.
Solution Approach 2:
The spring section transforms the static rigid connection into a dynamic system that can adapt to thermal movements. The spring's ability to compress and expand allows the exhaust manifold to move relative to the cylinder head during thermal cycles without compromising the fastening integrity.
2Stability of the object's composition
If a spring section is added to provide elastic support, then thermal movement is accommodated, but the manufacturing complexity increases and spring force scalability is limited
Solution Approach 1:
The fastening nut is divided into two separate parts: a rigid nut body and a separate spring section. This segmentation allows each component to be manufactured using optimized processes (cold extrusion for the nut body, stamping for the spring section) and then assembled together, reducing overall manufacturing complexity while maintaining the benefits of elastic support.
Solution Approach 2:
The spring section acts as an intermediary element between the rigid nut body and the exhaust manifold. This separate component mediates the interaction between the rigid fastening system and the thermally active exhaust manifold, providing elastic compliance while allowing both the nut body and manifold to be manufactured using their respective optimal processes.
3Reliability
If the support surface is on the cylinder head, then the fastening is stable, but large through-holes are required in the exhaust manifold
Solution Approach 1:
Instead of supporting the nut on the cylinder head as in conventional designs, the patent inverts the support arrangement by having the spring section support the exhaust manifold directly. This reversal eliminates the need for large through-holes in the exhaust manifold while maintaining fastening reliability through the elastic support provided by the spring.
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 resilient and secure fixation of the exhaust manifold, maintaining minimum clamping force despite heat/cold changes, preventing leaks and deformation of threaded bolts, while allowing for scalable spring force and simplified production.
Implementation Method 1
a support surface, with which the spring part is supported directly or indirectly on the exhaust manifold, in that the spring part can be elastically preloaded in the axial direction
Implementation Method 2
braking torque means for increasing the loosening torque
Data Source
Figure 1~3
AI summary
The invention relates to a securing nut (3) for fastening an exhaust manifold (2) to a cylinder head (4) of a combustion engine (1) by screwing in an axial fixing direction (F), having an external threaded bolt that is held on the cylinder head and passes through a through-opening (5) in the exhaust manifold, wherein the securing nut comprises an internal threaded portion for screwing together with the external threaded bolt and preferably braking moment means for increasing the release moment, further comprising a support face (17) for indirect or direct axial support on the exhaust manifold (2), wherein the support face is formed on a radially protruding spring portion that is able to be axially pretensioned in an axial direction, wherein the securing nut is formed in a multipart manner and comprises a nut body (8), extending axially from a rear end to an axial end face (16) at the front in the fixing direction, with a shank portion (14) having the axial end face, and at least one first spring part (10) that is separate from the nut body and is fastened captively to the nut body via securing means and is configured in particular as a spring washer, and wherein the internal threaded portion is formed on the nut body and wherein the first spring part forms the spring portion with the support face, which forms a front-most axial end, in the axial fixing direction, of the securing nut, relative to which the end face of the shank portion is set back and axially spaced apart with respect to the axial fixing direction.