Eccentric Turbine Bypass Valve Sealing to Prevent Leakage and Sticking
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Solution Overview
Problem
Known turbine bypass valves face manufacturing challenges, leakage issues, and sticking problems, leading to reduced performance and premature failure due to contact with the housing, especially under heat stress.
Innovation Solution
A rotary turbine bypass valve with an eccentric valve rotor and a seal portion that minimizes radial separation with the bypass port, using abradable materials for sealing and reducing contact with the valve chamber walls, thereby enhancing sealing efficiency and reducing wear and actuator load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a known rotary valve design is used, then the valve can control exhaust gas flow, but gas leaks past the valve rotor to the bypass port reducing system performance
Solution Approach 1:
The valve rotor is designed with an asymmetric profile where one side is radially spaced from the bypass port while the other side approaches it. This asymmetric geometry creates a sealing surface that contacts the bypass port wall during rotation, preventing gas leakage without requiring the rotor to be perfectly concentric with the valve axis.
Solution Approach 2:
The sealing function is localized to a specific region of the valve rotor that is designed to contact the bypass port wall. Only the portion of the rotor adjacent to the bypass port requires precise sealing properties, while other regions can have different geometric characteristics to facilitate rotation and actuation.
2Reliability
If the valve rotor contacts the housing to seal, then sealing improves, but the valve rotor sticks and jams particularly under heat stress
Solution Approach 1:
The asymmetric rotor design ensures contact with the bypass port wall occurs only in a localized region during specific phases of rotation. The radial spacing in other regions prevents continuous contact and potential sticking, allowing the valve to seal effectively without jamming under heat stress.
Solution Approach 2:
The sealing function is segmented to occur only at the bypass port interface rather than requiring continuous contact around the entire rotor perimeter. This localized sealing approach reduces the total contact area and minimizes the risk of sticking while maintaining sealing effectiveness.
3Reliability
If the valve rotor contacts the housing, then sealing may improve, but excessive wear occurs and additional load is placed on the actuator
Solution Approach 1:
The asymmetric rotor geometry concentrates sealing contact to a minimal area adjacent to the bypass port. This reduces the overall contact surface between the rotor and housing, thereby minimizing wear accumulation and extending valve operational life while maintaining adequate sealing.
Solution Approach 2:
The sealing function is segmented to a specific zone rather than distributed around the entire rotor. This localized approach reduces the cumulative wear on the rotor-housing interface and decreases the frictional load on the actuator, extending component lifetime.
4Ease of manufacture
If a concentric valve rotor design is used, then manufacturing is simpler, but the radial separation from the bypass port remains constant preventing effective sealing
Solution Approach 1:
The valve rotor employs an asymmetric design where the radial distance to the bypass port varies during rotation. This allows the rotor to achieve minimal radial separation and contact the bypass port wall for effective sealing, while still being manufacturable using standard machining processes.
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 improves sealing efficiency, reduces leakage, and extends the operational lifetime of the valve and actuator by minimizing contact and wear, while allowing for effective bypassing of exhaust gas without jamming or sticking.
Implementation Method 1
a first region of abradable material located on a first side of the bypass port when the valve rotor is in the second position, and a second region located on a second side of the bypass port
Implementation Method 2
the valve rotor contacts the abradable material to form a seal therewith
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A rotary turbine bypass valve (30) comprises a valve chamber (31) positioned at a junction of an inlet port (30b), an outlet port (30a) and a bypass port (30c), the inlet port configured for fluid communication with a flow of exhaust gas from an engine, the outlet port configured for fluid communication with an inlet of a turbine, and the bypass port configured for fluid communication with an exhaust aftertreatment device; and a valve rotor (33a) supported for rotation, about a valve axis, within the valve chamber. The valve rotor is rotatable about the valve axis between a first position in which the valve rotor permits gas flow through the bypass port and a second position in which the valve rotor blocks gas flow through the bypass port. The valve rotor is eccentric such that it includes a seal portion (38) which is a portion of the valve rotor within the valve chamber which is furthest radially spaced from the valve axis; and as the valve rotor moves from the first position to the second position the seal portion moves towards the bypass port such that the radial separation between the valve rotor and the bypass port decreases to a minimum when the valve rotor is in the second position in which the seal portion is adjacent the bypass port.