Engine Flap Bearing Projections for Thermal Leak Tightness
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Solution Overview
Problem
Flap devices in internal combustion engines face challenges in maintaining high tightness and preventing leaks during large temperature fluctuations, especially in thermally stressed areas like the exhaust system, due to thermal expansion of components made from different materials, which often results in jamming or leakage issues.
Innovation Solution
The design incorporates bearings with projections that extend over a partial circumference of the flap body, covering the gap between the inner wall and the flap body, and utilizing these projections as both sealing and stop surfaces to ensure complete closure and prevent jamming, reducing the need for additional stops or components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clearances are provided to prevent jamming due to thermal expansion, then the reliability of smooth operation is improved, but the sealing performance deteriorates
Solution Approach 1:
The bearing is divided into multiple segments: the bearing proper for support, and separate projections extending from the bearing outer circumference. These projections act as independent sealing elements that can be positioned optimally without interfering with the clearance needed for thermal expansion.
Solution Approach 2:
The projections serve as intermediary elements between the bearing and the flap body. They extend into the channel to close gaps and prevent leakage paths, while the bearing itself maintains the necessary clearance for smooth rotational movement during thermal expansion.
2Manufacturing precision
If projections extend into the channel to close gaps and prevent leakage, then the sealing performance is improved, but the risk of jamming increases
Solution Approach 1:
The projections are positioned locally at specific locations on the bearing outer circumference, extending only into the regions where gaps and leakage paths occur. The bearing areas that contact the flap body during rotation maintain appropriate clearance, providing local sealing without global interference with movement.
3Manufacturing precision
If additional sealing components are added to improve tightness, then the sealing performance is improved, but the device complexity increases
Solution Approach 1:
The sealing function is merged with the bearing structure. The projections are formed as integral parts of the bearing, combining the support function and sealing function into a single component, thereby eliminating the need for separate sealing elements.
Solution Approach 2:
The bearing serves multiple functions: it provides rotational support for the shaft and simultaneously creates sealing against the flap body through its projections. This multi-functionality reduces the total component count while maintaining both smooth operation and high sealing efficiency.
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 reduces leaks and ensures stable sealing and operation even with thermal expansion, eliminating the risk of jamming and allowing for smooth movement of the flap body while maintaining high sealing efficiency without additional components or stops.
Implementation Method 1
the changing temperatures result in different thermal expansions of components made of different materials
Data Source
Figure 1~2
AI summary
Flap devices for internal combustion engines having a flow housing (10), in which a flow-through duct (12) is formed, a flap body (14), which is rotatably arranged in the duct (12), a shaft (16), on which the flap body (14) is fixed, and bearings (18, 22), which are arranged in bearing positions (20, 24) of the flow housing (10) protruding into the flow-through duct (12) and in which the shaft (16) is rotatably mounted, are known. In order to achieve a high level of tightness, independently of thermal expansions, according to the invention, each bearing (18, 22) has at least one protrusion (26, 28) extending over a partial circumference of the respective bearing (18, 22), which protrudes axially into the duct (12) over a region (34) close to the shaft of an outer flap edge (36) of the flap body (14) and is arranged outside of the region through which the flap body (14) can travel, viewed in the circumferential direction.