Turbocharger Variable Nozzle Thermal Isolation Design
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Solution Overview
Problem
Conventional variable nozzle devices in turbochargers face issues such as complex structure, reduced assembly productivity, and thermal stress due to temperature gradients, leading to efficiency losses and increased manufacturing costs.
Innovation Solution
A turbocharger design with a mechanically and thermally insulated variable nozzle device, featuring a retainer ring, an insert, and a turbine housing, where the insert is connected to the nozzle ring and the retainer ring is connected to the bearing housing, preventing direct contact and thermal stress, and utilizing a 360° connection and elastic restoration for sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the variable nozzle device is directly connected to the turbine housing, then the structure is simpler, but thermal stress occurs due to temperature gradients causing thermal deformation and efficiency loss
Solution Approach 1:
The variable nozzle device is segmented into separate components: the insert (exposed to high temperature exhaust gas), the nozzle ring, and the retainer ring (located in the bearing housing). This segmentation allows each component to operate at its optimal temperature, preventing thermal stress and deformation while maintaining structural integrity and operational efficiency.
Solution Approach 2:
The retainer ring acts as an intermediary component that mechanically connects the insert to the bearing housing without direct thermal contact. This intermediary structure isolates the temperature gradient, preventing thermal stress from affecting the bearing housing and connected components while maintaining the structural connection.
2Ease of manufacture
If the variable nozzle device is directly connected to the turbine housing, then manufacturing is simpler, but assembly productivity is reduced due to complex assembly requirements
Solution Approach 1:
The device is divided into separable components (insert, nozzle ring, retainer ring) that can be manufactured independently using standard machining processes. This segmentation allows each component to be manufactured separately and then assembled, improving overall assembly productivity despite the increased number of parts.
Solution Approach 2:
The insert is pre-assembled with the nozzle ring before installation into the bearing housing. This preliminary assembly simplifies the final installation step and reduces the complexity of the overall assembly process, improving productivity by breaking down the assembly into manageable stages.
3Reliability
If precise clearances are provided for thermal expansion, then thermal deformation is prevented, but the device complexity increases and manufacturing costs rise
Solution Approach 1:
By segmenting the variable nozzle device into separate components exposed to different temperatures, each component can expand or contract independently within its own thermal environment. This eliminates the need for complex pre-calculated clearances to accommodate differential thermal expansion between components, simplifying the design while preventing thermal deformation.
Solution Approach 2:
The design changes the thermal parameters of different components by positioning them in different thermal zones. The insert operates at high temperature while the retainer ring operates at bearing housing temperature, allowing each component to be designed for its specific thermal conditions without requiring complex clearance accommodations for temperature gradients.
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to a turbocharger equipped with a variable nozzle device, in which the retainer ring, insert and turbine housing are mechanically and thermally isolated. Consequently, there is no danger of deterioration of the operating efficiency of the variable nozzle device, sealing between the retainer ring and the nozzle is also improved, and productivity is increased because the manufacturing and assembly of the variable nozzle device is simpler. In addition, since the design is simple, there is no need to manufacture the various parts of the turbocharger to a fine tolerance and manufacturing costs are thereby reduced. The invention comprises a bearing housing between the compressor housing and the turbine housing, and an insert which is built between said bearing housing and said turbine housing. Said insert is comprised of a tubular component attached to the inside of the turbine housing outlet and a nozzle which extends radially outwards from the end of said tubular component. Said nozzle is equipped with a variable nozzle device in which a plurality of vanes are axially disposed at intervals between said retainer ring and the nozzle.