Exhaust Gas Recirculation Valve Guide Bushing Gap Design
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Solution Overview
Problem
Existing exhaust gas recirculation valves in internal combustion engines face issues with deposits and contamination leading to malfunctions, sealing damage, and jamming due to friction and scoring between the valve rod and guide bush, which reduces their service life and assembly efficiency.
Innovation Solution
A design featuring a circumferential gap between the valve rod and guide bush, with specific guide sections and scraping edges to prevent friction and collect contaminants, ensuring long-lasting tightness and minimizing contamination in the sliding area, thereby preventing jamming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the valve rod is guided in the guide bushing without a circumferential gap, then the sealing function is maintained, but friction and scoring occur between the valve rod and guide bushing leading to deposits and malfunctions
Solution Approach 1:
The guide bushing is divided into multiple sections with different functions: a first section with a circumferential gap to collect contaminants, a second section with a constriction to further trap deposits, and a third section for guidance. This segmentation allows each zone to perform its specific function, preventing friction-induced scoring while maintaining sealing.
Solution Approach 2:
The circumferential gap acts as an intermediary zone between the valve rod and the sealing area. It collects and traps contaminants before they can cause friction and scoring in the sealing region, effectively mediating the interaction between the valve rod and guide bushing.
2Reliability
If a radial sealing ring is used to prevent contaminants from entering the actuator area, then sealing is improved, but the sealing ring wears out quickly due to scoring on the valve rod
Solution Approach 1:
The circumferential gap and constriction in the guide bushing perform preliminary action by collecting and trapping contaminants before they reach the sealing ring. This prevents the sealing ring from contacting sharp edges and scoring surfaces, extending its service life while maintaining sealing function.
3Reliability
If additional sealing components like ribs and elastic membranes are added, then sealing is improved, but the device complexity and assembly effort increase
Solution Approach 1:
The sealing function is merged into the guide bushing structure itself through the circumferential gap and constriction features. This eliminates the need for separate sealing components like ribs and elastic membranes, reducing device complexity while maintaining effective sealing through the integrated design.
4Ease of operation
If the guide bushing has a continuous sliding contact with the valve rod, then guidance is maintained, but deposits accumulate causing the valve to jam
Solution Approach 1:
The guide bushing is segmented into zones with different characteristics: a first section with a circumferential gap to collect contaminants, a second section with a constriction to trap deposits, and a third section for active guidance. This segmentation allows continuous guidance while preventing deposit accumulation that would cause jamming.
Data Source
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AI summary
Exhaust gas recirculating valves for internal combustion engines are known, said valves comprise a housing (2) with an exhaust gas inlet (4) and an exhaust gas outlet (6), a valve closing body (10), a valve rod (12) on which the valve closing body (10) is fixed and which can be moved by an actuator, a valve seat (8) between the exhaust gas inlet (4) and the exhaust gas outlet (6), wherein the valve closing body (10) can be lowered onto said valve seat by moving the valve rod (12) and the valve closing body (10) can be raised from said valve seat by an opposing movement, a guide bushing (14) via which the valve rod (12) is guided in the housing (2), and a sealing ring (18) which lies on the guide bushing (12) end opposite the valve closing body (10). However, jamming or loss of sealing tightness of the valve are frequent problems. The invention therefore proposes forming a peripheral gap (32) between the valve rod (12) and the guide bushing (14) in a first section (30) of the guide bushing (14), said section pointing towards the sealing ring (18). The mechanical load of the sealing ring (18) is thereby reduced and the guiding sections are shortened.