Variable Geometry Turbine Cam Actuation
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Solution Overview
Problem
Current variable geometry turbochargers face challenges with complex and costly sealing arrangements for push rods, leading to increased complexity, cost, and thermal inertia due to bulky designs, which also result in pressure differentials during exhaust gas filling and scavenging.
Innovation Solution
A compact variable geometry turbine assembly with an actuation mechanism using a cam member and carrier member to move a movable wall member axially, eliminating the need for push rods and their associated sealing requirements, and allowing for a self-contained, easy-to-install cartridge design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If push rods with sealing arrangements are used to move the movable wall member, then the variable geometry function is achieved, but the device complexity and cost increase due to expensive and wear-prone sealing systems
Solution Approach 1:
The patent extracts and eliminates the push rod and sealing arrangement from the system by adopting a direct cam-lobe actuation mechanism. The cam member, integrated into the turbine housing, directly acts on the movable wall member through its profiled surface, removing the intermediate push rod component and its associated sealing requirements entirely.
Solution Approach 2:
The cam member serves as an intermediary element that translates rotational motion into axial movement of the movable wall member. The profiled surface of the cam member acts as the mediating mechanism that converts the rotational movement of the turbine wheel into the desired axial displacement of the wall member, eliminating the need for complex sealing arrangements.
2Reliability
If push rods and yoke mechanism are mounted in a cavity in the turbine housing, then sealing requirements are eliminated, but the overall turbine housing size increases and thermal inertia increases
Solution Approach 1:
The cam member is integrated directly into the turbine housing structure, merging the actuation mechanism with the housing itself. This eliminates the need for a separate cavity to house the push rods and yoke mechanism, thereby reducing the overall housing volume while maintaining the functionality of moving the movable wall member without sealing requirements.
Solution Approach 2:
The actuation mechanism transitions from a three-dimensional cavity-based arrangement to a two-dimensional profiled surface approach. The cam member's profiled surface operates in a planar manner, allowing the movable wall member to be actuated without requiring a bulky three-dimensional cavity, thus reducing the housing volume.
3Device complexity
If push rods are used to move the movable wall member, then the actuation mechanism is simple, but pressure differentials occur during exhaust gas filling and scavenging
Solution Approach 1:
The patent replaces the mechanical push rod system with a cam-lobe actuation mechanism that utilizes the kinetic energy and motion of the turbine wheel itself. The profiled surface of the cam member converts rotational motion directly into axial motion, eliminating the mechanical linkage that caused pressure differentials during exhaust gas filling and scavenging.
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 provides a cost-effective, durable, and compact variable geometry turbine arrangement that reduces pressure differentials and eliminates the need for expensive and wear-prone sealing systems, enhancing operational efficiency and ease of installation.
Implementation Method 1
a cam member provided with at least one formation; the carrier member being coupled to at least one co-operating formation such that as the at least one co-operating formation is moved in the axial direction, the carrier member is moved in the axial direction
Data Source
AI summary
A variable geometry turbine assembly comprising an inlet passageway, extending radially inwards towards a turbine wheel, defined between a surface of a movable wall member and a facing wall and an actuation mechanism arranged to move the movable wall member axially and comprising a cam member provided with at least one formation and a carrier member axially coupled to at least one co-operating formation, wherein one of the at least one formation and the at least one co-operating formation is a radially extending formation, the at least one formation or the at least one co-operating formation extending in both the circumferential direction and the axial direction such that as the cam member is rotated relative to the carrier member, the at least one formation and the at least one co-operating formation engage such the movable wall member is moved in the axial direction.