Variable Nozzle Device Thermal Deformation Management
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Solution Overview
Problem
Variable-geometry type exhaust turbochargers face performance deterioration and malfunction due to thermal deformation of nozzle device components, particularly at high temperatures from diesel and gasoline engines, leading to potential damage and increased costs.
Innovation Solution
The design includes a second plate-shaped member with a larger thickness than the first plate-shaped member to increase heat capacity and strength, reducing thermal deformation, and a nozzle support with a small-diameter center portion and larger-diameter end portions to manage thermal expansion, preventing damage and maintaining performance under high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nozzle device components are made with standard thickness, then the device complexity and manufacturing cost are reduced, but thermal deformation occurs at high temperatures causing performance deterioration and malfunction
Solution Approach 1:
The patent applies local quality by making the second plate-shaped member (nozzle plate) with a larger thickness than the first plate-shaped member (nozzle mount). This localized thickness increase is specifically applied to the component (nozzle plate) that is more susceptible to thermal deformation, providing enhanced thermal resistance where needed without unnecessarily complicating the entire nozzle device structure.
2Strength
If the second plate-shaped member is made with larger thickness, then thermal deformation is reduced and strength is increased, but the weight and manufacturing cost increase
Solution Approach 1:
The patent implements local quality by selectively increasing the thickness of only the second plate-shaped member (nozzle plate) while keeping the first plate-shaped member (nozzle mount) at standard thickness. This targeted approach provides the necessary thermal resistance and strength to prevent deformation where it is most critical, without unnecessarily increasing the overall weight of the entire nozzle device.
3Reliability
If heat-resistant alloys are used instead of stainless steel, then thermal deformation resistance is improved, but production costs increase significantly
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameter (thickness) of the nozzle plate rather than changing the material parameter. Instead of using expensive heat-resistant alloys, the invention achieves improved thermal deformation resistance by increasing the thickness of the second plate-shaped member, thereby maintaining cost-effectiveness while achieving the desired thermal performance.
4Ease of manufacture
If the nozzle support has uniform diameter, then manufacturing is simplified, but thermal expansion management is insufficient leading to potential damage
Solution Approach 1:
The patent implements asymmetry by designing the nozzle support with non-uniform diameter - featuring a small-diameter center portion and larger-diameter end portions. This asymmetric geometry is specifically tailored to manage thermal expansion patterns, providing enhanced support and stability at the ends where expansion forces are greatest, while maintaining manufacturing feasibility through a relatively simple stepped configuration.
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
This configuration effectively reduces thermal deformation and associated shearing forces, preventing damage to the nozzle support and plate, thus maintaining the performance of the variable nozzle device and allowing for the adjustment of boost pressure even at high temperatures, while also reducing production costs by using stainless steel instead of expensive heat-resistant alloys.
Implementation Method 1
the second plate portion is formed to have a larger thickness than the first plate portion... increase the heat capacity of the second plate portion
Implementation Method 2
thermal deformation may occur at various parts of the variable nozzle device... increase the strength of the second plate portion
Implementation Method 3
a nozzle support with a small-diameter center portion and larger-diameter end portions to manage thermal expansion
Data Source
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AI summary
A variable nozzle device includes: a first plate-shaped member having a first plate portion having an annular shape and being fixed to a bearing housing; a second plate-shaped member having a second plate portion which has an annular shape and which defines a nozzle flow passage between the first plate portion and the second plate portion, the second plate portion having a surface disposed so as to face the first plate portion and another surface disposed so as to face at least partially a scroll flow passage formed inside a turbine housing; at least one nozzle support having, with respect to an axial direction of the nozzle support, an end coupled to the first plate portion and another end coupled to the second plate portion; at least one nozzle vane rotatably supported between the first plate portion and the second plate portion; and a variable nozzle mechanism configured to change a vane angle of the at least one nozzle vane. The second plate portion is formed to have a larger thickness than the first plate portion.