Wastegate Valve Articulation Limits to Prevent Turbo Trapping
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Solution Overview
Problem
The existing wastegate valve systems in turbochargers face challenges in accurately controlling the degree of articulation due to manufacturing tolerances and differential thermal expansion, leading to potential valve trapping and reduced fluid flow efficiency.
Innovation Solution
The introduction of opposed corresponding limit areas on the valve member and support member, which restrict articulation by collision, allowing controlled movement and distributing wear forces, thereby maintaining precise articulation control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the valve member is allowed to articulate freely to accommodate manufacturing tolerances and thermal expansion, then the reliability of the wastegate system is improved, but the precision of articulation control deteriorates leading to potential valve trapping
Solution Approach 1:
The patent introduces limit areas that define maximum articulation angles by colliding with corresponding limit areas on the support member. This changes the parameter of articulation freedom from unlimited to bounded, maintaining reliability through tolerance accommodation while preventing valve trapping by limiting excessive articulation.
2Measurement precision
If the valve member is constrained to limit articulation to prevent valve trapping, then the precision of articulation control is improved, but the ability to accommodate manufacturing tolerances and thermal expansion deteriorates
Solution Approach 1:
The patent applies local quality by creating specific limit areas on both the valve member and support member that selectively constrain articulation only in extreme positions. The majority of the articulation range remains free to accommodate tolerances and thermal expansion, while only the boundary regions are limited to prevent valve trapping.
3Adaptability or versatility
If the valve member articulates with large clearance to accommodate thermal expansion, then the adaptability to thermal conditions is improved, but the fluid flow efficiency deteriorates due to reduced sealing effectiveness
Solution Approach 1:
The patent applies preliminary anti-action by pre-positioning limit areas that will collide before excessive articulation can occur. This prevents the valve from articulating to positions where sealing effectiveness would be compromised, thereby maintaining fluid flow efficiency while still allowing sufficient clearance for thermal expansion.
Data Source
AI summary
A turbine comprises a turbine housing defining a turbine inlet upstream of a turbine wheel and a turbine outlet downstream of the turbine wheel; and a wastegate valve assembly comprising at least one movable valve member mounted on a movable support member within a wastegate chamber which communicates with the turbine inlet upstream of the turbine, and has one or more chamber outlets which communicate with an outlet of the turbine. The valve member is permitted to articulate slightly about the support member, with the amount of articulation in respective directions being limited by collisions between a respective limit point on a limit area on a rear surface of a sealing portion of the valve member and a respective limit point on limit area on a front surface of the support member.