Sealing Arrangement for Engine Control Device Shaft Leakage
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Solution Overview
Problem
Existing sealing arrangements for control devices in internal combustion engines, such as exhaust gas recirculation flap valves, fail to adequately prevent leakage and are costly to manufacture due to precise requirements.
Innovation Solution
A sealing arrangement featuring a circumferential groove on the shaft surrounded by a sealing device, combined with a collar bush and a slit metal sealing ring, creates turbulences and pressure reductions to enhance sealing efficacy while minimizing leakage, and is cost-effective to produce and assemble.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing arrangement with collar bush and sliding bush is used to prevent exhaust gas intrusion into bearings, then bearing protection is improved, but leakage values are insufficient and manufacturing costs are high
Solution Approach 1:
The sealing function is divided into multiple segments: the collar bush provides primary sealing at the bearing bore, the sliding bush provides secondary sealing along the shaft, and the groove with sealing device provides tertiary sealing. This segmentation allows each component to contribute to overall sealing effectiveness without requiring any single component to achieve perfect sealing alone, thereby reducing leakage while maintaining reliability.
Solution Approach 2:
The groove formed in the shaft behind the bearing acts as an intermediary structure that works with the sealing device to create additional sealing zones. This intermediary feature redirects and contains potential leakage paths, preventing direct exhaust gas intrusion into the bearing area while reducing the need for overly tight tolerances in the primary sealing components.
2Loss of substance
If precise manufacturing is required to achieve adequate sealing, then leakage is reduced, but production costs increase
Solution Approach 1:
By dividing the sealing function across multiple components (collar bush, sliding bush, groove with sealing device), the system achieves effective sealing without requiring any single component to have extremely tight tolerances. Each component can be manufactured with standard tolerances, reducing overall manufacturing cost while maintaining adequate leakage prevention through the combined effect of multiple sealing zones.
Solution Approach 2:
The groove is strategically positioned behind the bearing on the shaft, creating a localized sealing zone where exhaust gas pressure is already reduced. This local quality approach concentrates sealing efforts where they are most effective, allowing other areas to use simpler, less expensive sealing arrangements.
3Reliability
If multiple sealing components (collar bush, sliding bush, sealing disc) are used, then sealing effectiveness is improved, but device complexity increases
Solution Approach 1:
The collar bush and sliding bush are merged into a single integrated component that performs both sealing functions simultaneously. The collar bush seals at the bearing bore interface while the sliding bush seals along the shaft surface, combining multiple sealing actions into one piece rather than requiring separate components for each function.
Solution Approach 2:
The integrated bush component serves multiple functions: it provides sealing at the bearing bore, seals along the shaft, supports the shaft in the bearing bore, and guides the shaft movement. This multi-functionality reduces the total number of components needed while maintaining or improving sealing effectiveness.
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 significantly reduces leakage flows along the shaft, prolongs bearing life, and prevents soiling, while being easier and less expensive to manufacture and assemble, maintaining a high degree of tightness and operational efficiency.
Implementation Method 1
By forming a circumferential groove on the shaft behind the bearing, seen from the channel, which grove is radially surrounded by a sealing means cooperating with the groove, the forming of turbulences in the groove or an improved sealing by the groove is achieved
Implementation Method 2
A sealing flow thus prevails on the rear side of the bearing that leads to a pressure balance with the inside of the channel so that the exhaust gas flow is not drawn into the bearing
Data Source
AI summary
A sealing arrangement for a control device of an internal combustion engine includes a housing. A channel is formed in the housing. The channel has a gas flow therethrough. A control member controls a flow of the gas in the channel. The control member is arranged on a shaft. A bearing supports the shaft in a bearing bore of the housing. A vent bore extends in the housing from an inner wall of the channel on an inlet side of the control member to a rear side, facing outward from the channel, of the bearing arranged in the housing, and into the bearing bore. A first groove is formed in the shaft behind the bearing. The first groove is configured so as to be circumferential when seen from the channel. The first groove is surrounded radially by a sealing device which is configured to cooperate with the first groove.