Exhaust Manifold Nut with Spring Section for Thermal Sliding
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Solution Overview
Problem
Existing internal combustion engine designs face issues with the exhaust manifold sliding due to temperature fluctuations, leading to bending moments on threaded bolts, which can result in plastic deformation or detachment, and nut loosening, causing the manifold to become partially detached.
Innovation Solution
The solution involves using a nut with braking torque means and a spring section that provides two support surfaces, one on the cylinder head and another on the exhaust manifold, to increase the loosening torque and absorb displacement forces, while maintaining a radial gap to absorb bending moments, ensuring a robust connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the exhaust manifold is fixed to the cylinder head using conventional threaded bolts and nuts, then the manifold can be securely attached initially, but the manifold tends to slide due to temperature fluctuations during operation, causing bending moments on the threaded bolts
Solution Approach 1:
The fastening system is divided into separate functional components: a threaded bolt for initial attachment, a nut for securing, a spring section for absorbing displacement forces, and braking torque means for preventing loosening. This segmentation allows each component to address specific aspects of the sliding problem independently.
Solution Approach 2:
The spring section changes its elastic parameters dynamically to absorb displacement forces caused by thermal expansion and contraction. The braking torque means alters the friction parameters between the nut and threaded bolt to increase resistance against loosening during thermal cycles.
2Force
If the nut is tightened to secure the exhaust manifold, then the manifold is firmly attached, but the bending moments caused by thermal sliding can cause the threaded bolts to tear off or the nuts to become detached
Solution Approach 1:
The spring section is pre-installed between the nut and the exhaust manifold to provide cushioning against bending moments before they occur during thermal cycling. This elastic element absorbs the shock of thermal expansion and contraction, preventing the bolt from tearing off or the nut from detaching.
Solution Approach 2:
The spring section acts as an intermediary element between the nut and the exhaust manifold, mediating the force transmission during thermal cycles. It converts the direct mechanical stress into elastic deformation, protecting the bolt-nut connection from damaging bending moments.
3Ease of manufacture
If the through-opening in the exhaust manifold is sized to accommodate the threaded bolt, then the bolt can pass through for fastening, but the nut or sleeve cannot be supported directly on the cylinder head or seal
Solution Approach 1:
The support surface is extended into the radial dimension, creating an annular support surface that extends radially outward from the threaded bolt. This allows the nut or sleeve to be supported on this extended surface, which is spaced radially from the bolt, providing stable support without requiring a larger through-opening.
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 configuration significantly enhances the connection between the internal combustion engine and the exhaust manifold, preventing detachment and maintaining a secure attachment even under temperature-related sliding, thereby reducing the force load on fastening means.
Implementation Method 1
the nut (9) with a second support surface (16) for direct or indirect support on the exhaust manifold (2), wherein the second support surface (16) is arranged on a spring section (15) of the nut, which is elastically prestressed in the axial direction in the assembled state
Implementation Method 2
braking torque means (10) are provided on the nut (9) and/or the threaded element (6), which ensure that the friction between the nut (9) and the threaded bolt (6) is increased or increase the loosening torque
Data Source
Figure 1~6
Figure 7~8
AI summary
The invention relates to an internal combustion engine (1) having a cylinder head (4), to which an exhaust manifold (2) is fastened by means of fastening elements (3), wherein the fastening elements (3) comprise at least one threaded bolt (6) retained on the cylinder head (4) and passing through a passage opening (8) in the exhaust manifold (2) and at least one nut (9) screwed onto the threaded bolt (6) by means of an internal thread section (11), by means of which nut force is applied to the exhaust manifold (2) in the direction of the cylinder head (4), wherein the nut (9) is directly or indirectly supported axially on the cylinder head (4) and/or on a seal lying on the cylinder head by means of a first supporting surface (14) and is directly or indirectly supported axially on the exhaust manifold (2) by means of a second supporting surface, wherein the first supporting surface (14) is formed by an end face of an axial supporting section (13) passing through the passage opening (8), the inner circumferential surface (19) of said supporting section being located at a radial distance from the threaded bolt (6), wherein the supporting section (13) is formed by the nut (9) or an optional sleeve. According to the invention, the fastening elements (3) comprise braking torque means (10) for increasing the loosening torque, and the second supporting surface (16) is formed on a radially protruding spring section (15) of the nut (9) that is elastically preloaded in the axial direction.