Variable Nozzle Turbocharger Vane Cutout Design
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Solution Overview
Problem
The existing variable nozzle mechanisms in turbochargers suffer from scratching of the gas inflow passage walls due to the sliding of nozzle vanes, which affects the performance and longevity of the system.
Innovation Solution
The variable nozzle unit features nozzle vanes that are rotatably supported on both sides and pivot about a pivotal axis parallel to the rotational axis of the turbine impeller, with an end face cutout region closer to the leading edge than the pivotal axis, creating a larger gap with the flow passage wall surfaces to reduce scratching during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If nozzle vanes are arranged in the gas inflow passage to enable variable geometry control, then the turbocharger can adjust exhaust gas flow and improve performance, but the sliding of nozzle vane end faces on the wall surface causes scratching and reduces reliability
Solution Approach 1:
A bearing is introduced as an intermediary component between the nozzle vane and the housing wall surface. The bearing supports the nozzle vane at its end face, enabling relative movement while preventing direct sliding contact between the vane and the housing, thereby eliminating scratching of the wall surface
Solution Approach 2:
The direct mechanical sliding contact between the nozzle vane end face and the housing wall surface is replaced with a bearing-supported rotation mechanism. This substitution transforms the harmful sliding friction into a controlled rotational movement supported by the bearing, protecting the housing from damage
2Ease of operation
If nozzle vanes are made to pivot about an axis to enable opening degree adjustment, then flow control is improved, but the sliding motion generates harmful friction and wear on the gas inflow passage walls
Solution Approach 1:
The bearing acts as a mediator between the nozzle vane and the housing, supporting the vane at its end face. This allows the vane to pivot and adjust its opening degree while the bearing absorbs all sliding friction, preventing wear on the housing wall surface
Solution Approach 2:
The nozzle vane is designed to rotate periodically about its pivot axis to adjust opening degrees, while the bearing ensures that this periodic rotational action does not generate harmful sliding friction on the housing, converting the motion into a controlled rotation rather than harmful sliding
Data Source
AI summary
A variable nozzle unit is used in a turbine having a gas inflow passage which is sandwiched between a first flow passage wall surface and a second flow passage wall surface facing each other and through which a gas flowing from a scroll flow passage into a turbine impeller flows. The variable nozzle unit includes nozzle vanes, each of which is rotatably supported on both sides thereof by the first flow passage wall surface side and the second flow passage wall surface side and pivots about a pivotal axis parallel to the rotational axis of the turbine impeller in the gas inflow passage. An end face of the nozzle vane is formed with a cut face that is located closer to a leading edge than the pivotal axis, is cut out such that a gap between the cut face and the second flow passage wall surface is greater than other regions, and intersects the leading edge.