Shaft Valve Assembly for Low-Leakage EGR Flow Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing butterfly valves for exhaust gas recirculation systems in internal combustion engines face challenges in efficiently controlling gas flow, managing thermal expansion, and meeting stringent emission standards while minimizing leakage and manufacturing costs.
Innovation Solution
A valve assembly with a shaft valve and vane configuration that allows for precise flow control through a uniform diameter design, reduced contact surfaces, and customizable sealing bands and channels, enabling low leakage and adaptable flow rates without mechanical stops, and utilizing interchangeable shaft valves for various flow requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional butterfly valves are used for exhaust gas recirculation, then the valve structure is simple and manufacturing cost is low, but the flow control precision is insufficient and leakage is high
Solution Approach 1:
The valve is segmented into distinct functional components: a valve body with separately defined gas passage bore and valving bore, a shaft valve with vane, and sealing bands. This segmentation allows each component to be optimized for its specific function while maintaining manufacturability.
Solution Approach 2:
Different regions of the valve are given different properties: the shaft valve has uniform diameter for precise rotational control, the sealing bands have specific geometries (V-shaped or oval) for effective sealing, and the bearing surfaces are positioned at specific locations to support the shaft valve. This local differentiation improves flow control precision without requiring complete redesign of the entire valve structure.
2Reliability
If conventional valve designs are used, then manufacturing processes are straightforward, but thermal expansion effects are not adequately managed and leakage occurs
Solution Approach 1:
The valve design incorporates parameters that account for thermal expansion: the uniform diameter of the shaft valve and the specific positioning of bearing surfaces are designed to maintain proper clearances and sealing pressures under thermal loading conditions. The sealing bands are positioned and dimensioned to compensate for thermal growth of the valve components.
Solution Approach 2:
The design anticipates thermal expansion by providing adequate clearance between the shaft valve and valve body, and by positioning the sealing bands to maintain contact under expanded conditions. This beforehand cushioning prevents leakage that would occur if the valve were designed without considering thermal effects.
3Adaptability or versatility
If existing valve configurations are used, then the design is standardized and production is efficient, but adaptability to different flow requirements is limited
Solution Approach 1:
The valve body design with its gas passage bore and valving bore configuration allows a single basic valve structure to accommodate different shaft valve and vane combinations for various flow requirements. The interchangeable shaft valves with different vane configurations enable the same valve body to serve multiple flow control applications.
Solution Approach 2:
The shaft valve is designed to rotate freely within the valving bore without mechanical stops, allowing continuous adjustment of the vane angle and flow rate. This dynamic configuration enables adaptable flow control from fully closed to fully open positions, with any intermediate position achievable, providing versatility for different operating conditions.
4Reliability
If traditional sealing methods are used, then manufacturing is simple, but leakage control is insufficient and emission standards are not met
Solution Approach 1:
The sealing bands are given specific local geometries (V-shaped or oval cross-sections) at their engagement surfaces with the shaft valve. This localized sealing design concentrates the sealing function at critical interfaces, improving leakage prevention without requiring high precision throughout the entire valve assembly.
Solution Approach 2:
The sealing system combines different material properties: the sealing bands are made of materials suitable for high-temperature exhaust gas environments, while the shaft valve and valve body use materials with appropriate thermal expansion characteristics. This composite approach ensures reliable sealing under thermal loading while meeting emission standards.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Embodiments of the present disclosure present a valve assembly that includes a valve body having a gas passage bore, a valving bore extending along a longitudinal axis and intersecting the gas passage bore, a first bearing surface concentric with the longitudinal axis and a radially spaced apart second bearing surface concentric with the longitudinal axis, wherein an interface of the gas passage bore and the valving bore defines a flow port radially intermediate the first bearing surface and the second bearing surface. The valve assembly further includes a shaft valve extending along the longitudinal axis and rotatably mounted in the valving bore.