Turbocharger Vane Clearance Design for Binding Prevention
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Solution Overview
Problem
Variable geometry turbochargers face issues with vane binding and sticking due to inadequate clearance between vanes and nozzle surfaces, leading to control loss, stress on control mechanisms, and wear, especially under harsh temperature and pressure conditions.
Innovation Solution
Increasing the clearance between vanes and nozzle surfaces, particularly in the open position, to reduce the risk of binding and enhance exhaust flow development, while maintaining sufficient clearance to prevent excessive exhaust leakage, thereby optimizing vane positioning and actuator size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clearance between vanes and nozzle surfaces is increased, then risk of vane binding and sticking is reduced, but exhaust gas leakage increases
Solution Approach 1:
The patent applies different clearance values at different locations and vane positions. The clearance varies along the vane length and differs between closed and open positions, optimizing both sealing and binding prevention locally rather than using a uniform clearance throughout.
Solution Approach 2:
The clearance between vanes and nozzle surfaces is made dynamic rather than static. The clearance changes as the vanes pivot between closed and open positions, with larger clearance in the open position to prevent binding and smaller clearance in the closed position to reduce leakage.
2Loss of energy
If vane height is increased to reduce exhaust leakage, then sealing improves, but actuator force requirements and risk of binding increase
Solution Approach 1:
The patent optimizes vane height locally rather than uniformly. Different sections of the vane have different heights, with the vane being taller near the closed position for sealing and shorter near the open position to reduce actuator force requirements and binding risk.
Solution Approach 2:
The patent changes the geometric parameters of the vane, specifically the vane height and clearance dimensions, to optimize performance. By adjusting these parameters, the patent achieves adequate sealing while reducing the force required to pivot the vanes and minimizing binding risk.
3Loss of energy
If uniform small clearance is used between vanes and nozzle, then exhaust leakage is minimized, but vane binding and control loss occur under thermal conditions
Solution Approach 1:
The patent implements dynamic clearance that adapts to operating conditions. The clearance is smaller when vanes are closed to minimize leakage and larger when vanes are open to prevent binding, especially under thermal expansion conditions. This dynamic adjustment maintains reliability across varying temperature and pressure conditions.
Solution Approach 2:
The patent incorporates additional clearance as a preventive measure before binding occurs. By designing with larger clearance in the open position and along the vane length, the patent creates a buffer that prevents binding even when thermal expansion or manufacturing variations occur, cushioning against potential control loss.
Data Source
Figure 1
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Figure 3A~3B
AI summary
A turbine housing assembly can include a turbine housing that defines a rotational axis for a turbine wheel; and a cartridge receivable by the turbine housing, where the cartridge includes a nozzle wall component with an upper nozzle surface and a plate component with a lower nozzle surface, where the upper nozzle surface and the lower nozzle surface define a nozzle space, and vanes positioned in the nozzle space, where the vanes are pivotable between a closed vanes position of 0 percent open and a fully open vanes position of 100 percent open, and where, for a vanes position of at least 50 percent open and less than 75 percent open, an axial dimension of the nozzle space increases with respect to decreasing radius as measured from the rotational axis.