Turbocharger Compressor Adjustable-Trim Mechanism
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Solution Overview
Problem
Centrifugal compressor inlet-adjustment mechanisms require significant actuation force due to aerodynamic loads and internal friction, especially at low-flow and high compression ratio conditions, necessitating larger and more expensive actuators for proper operation.
Innovation Solution
The design incorporates a unison ring with notches and lever arms that reduce frictional resistance, along with blades and pivot pins made of plastic for lower friction, and a metal actuator rod with a plastic cover to minimize the actuation force needed, allowing for efficient adjustment of the inlet diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional inlet-adjustment mechanisms are used, then the compressor can adjust inlet area for different operating conditions, but significant actuation force is required due to aerodynamic loads and internal friction
Solution Approach 1:
A unison ring is introduced as an intermediary component between the actuator and the adjustable trim members. The unison ring receives actuation force and distributes it to multiple trim members simultaneously, reducing the force required at each individual connection point and minimizing internal friction in the adjustment mechanism.
Solution Approach 2:
The inlet-adjustment mechanism is divided into multiple independent adjustable trim members that can be individually positioned. This segmentation allows the system to achieve the desired inlet area adjustment through distributed movement of multiple components rather than requiring one component to handle the full actuation force.
2Reliability
If larger actuators are used to provide sufficient actuation force, then the mechanism can operate reliably, but the actuator becomes more expensive and occupies more space
Solution Approach 1:
The unison ring acts as a force-distributing intermediary that reduces the burden on the actuator. By distributing actuation force across multiple connection points and reducing internal friction, the system can use a smaller, less expensive actuator while maintaining reliable operation.
Solution Approach 2:
The adjustable trim members are designed to pivot or slide along defined paths, allowing dynamic adjustment of the inlet area. This dynamic mechanism enables reliable operation with reduced actuation force compared to rigid positioning systems.
3Strength
If more friction is present in the adjustment mechanism, then structural strength is improved, but the actuation force required increases significantly
Solution Approach 1:
The unison ring serves as a low-friction intermediary that transfers actuation force to the trim members. By using bearing surfaces or sliding contacts in the unison ring design, the system maintains structural strength while minimizing the friction that would otherwise require excessive actuation force.
Solution Approach 2:
Traditional high-friction mechanical connections are replaced with lower-friction alternatives such as bearing surfaces, sliding contacts, or pivot points. This substitution maintains the structural integrity of the mechanism while dramatically reducing the actuation force required to move the adjustable trim members.
Data Source
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AI summary
A centrifugal compressor for a turbocharger includes an inlet-adjustment mechanism operable to move between an open position and a closed position. The inlet-adjustment mechanism includes a plurality of blades disposed about the compressor air inlet and located within an annular space within the air inlet wall. The blades are pivotable about respective pivot points such that the blades extend radially inward from the annular space into the air inlet when the blades are in the closed position so as to form an orifice of reduced diameter relative to a nominal diameter of the inlet. The blades include lever arms that engage the outer periphery of a rotatable unison ring that is linked to a linear actuator for rotating the unison ring so as to pivot the blades.