Flap Device Inclined Abutment Thermal Expansion Compensation
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Solution Overview
Problem
Existing flap devices in internal combustion engines face issues with long-term tightness due to accretions and thermal expansions, leading to jamming and leakage, as precise manufacturing is required to avoid external abutments forming leaks and excessive turning.
Innovation Solution
A flap device with a lever surface featuring an inclined abutment region that compensates for axial and radial displacements caused by thermal expansions, eliminating the need for internal abutments and allowing for precise rotation angle limitation, even with different thermal expansions between the flap body and housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal abutments are formed in the duct to achieve tightness, then tightness is improved, but accretions on the shoulders cause tightness to deteriorate with increasing life span
Solution Approach 1:
The invention removes the internal abutment from the duct and replaces it with an external abutment on the lever. This extraction eliminates the problem of accretions forming on internal shoulders while maintaining the tightness function through the external abutment arrangement.
Solution Approach 2:
Instead of forming the abutment inside the duct on the stationary housing, the invention inverts the arrangement by placing the abutment surface on the moving lever. This allows the abutment to be part of the flap assembly rather than the housing, preventing accretion-related tightness deterioration.
2Reliability
If external abutments are used to limit rotation, then jamming is avoided, but thermal expansions cause the abutment to not be reached, resulting in excessive turning
Solution Approach 1:
The invention changes the geometric parameters of the lever, specifically forming an inclined abutment region on the lever surface. This inclination allows the lever to compensate for thermal expansion displacements, ensuring the abutment contact point is maintained despite temperature-induced dimensional changes in the housing and lever.
Solution Approach 2:
The inclined abutment region creates a dynamic contact point that can move along the inclined surface as thermal expansion occurs. This dynamic adjustment ensures continuous proper engagement between the lever and abutment throughout temperature variations, preventing both jamming and excessive turning.
3Reliability
If precise manufacturing is used to avoid leakage at external abutments, then tightness is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The inclined abutment region on the lever provides a self-compensating mechanism for thermal expansion, reducing the sensitivity to manufacturing tolerances. The geometry of the inclined surface allows for acceptable tolerance ranges while maintaining proper abutment contact and tightness, simplifying manufacturing requirements.
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 prevents jamming and leakage while maintaining high tightness, allowing for optimal closure regardless of temperature changes and material expansion differences, simplifying manufacturing and reducing tolerance-related failures.
Implementation Method 1
thermal expansions of the housings also occur which often differ from those of the flap body or the lever
Data Source
AI summary
A flap device for an internal combustion engine includes a flap body comprising at least one end position, a shaft which has the flap body arranged thereon, a housing which has a flow duct formed therein, an actuator which rotates the shaft in the flow duct, a lever which includes a lever surface, the lever being attached to the shaft outside of the flow duct, and an abutment which has the lever bear thereon in the at least one end position of the flap body. The flow duct includes a throughflow cross section which is regulated by a rotation of the shaft. The lever surface which faces toward the abutment includes an abutment region which is formed so as to be inclined in a direction of the abutment with respect to a radially outwardly extending straight line.