Variable Nozzle Turbine Structure to Prevent Pin Sticking
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Solution Overview
Problem
The concern with existing variable capacity turbines is that thermal deformation during operation can cause the nozzle mount to approach the bearing housing, leading to excessive insertion of the press-fitting pin, increased frictional resistance, and potential sticking, which compromises the holding structure and exposes the variable nozzle mechanism to abrasion and vibration risks.
Innovation Solution
The turbine design includes a first and second plate-like member forming a gas flow path, an annular member that rotates via an external driving force, link members connecting to variable nozzle vanes, a biasing member to maintain position, positioning pins with controlled gaps, and stopper portions to prevent excessive insertion, stabilizing the holding structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the press-fitting pin is used to position the nozzle mount and bearing housing, then the holding structure is formed, but thermal deformation causes the pin to be excessively inserted and stuck, compromising reliability
Solution Approach 1:
The positioning pin is divided into two separate pins: a first positioning pin for positioning the nozzle mount, and a second positioning pin for positioning the bearing housing. This segmentation prevents both pins from being excessively inserted simultaneously, avoiding sticking while maintaining holding structure stability.
Solution Approach 2:
A positioning hole is introduced as an intermediary feature in the nozzle mount, which guides and limits the insertion of the first positioning pin. This intermediary structure prevents excessive insertion of the pin while maintaining the necessary positioning function, thereby preventing sticking during thermal deformation.
2Reliability
If the first plate-like member approaches the second housing due to thermal deformation, then the holding structure is compromised, but the variable nozzle mechanism is exposed to abrasion and vibration risks
Solution Approach 1:
The biasing member is pre-installed to apply a preliminary biasing force that counteracts the thermal deformation force before the first plate-like member can approach the second housing excessively. This preliminary anti-action prevents the plate from moving into the harmful position, protecting the variable nozzle mechanism from abrasion and vibration.
Solution Approach 2:
The biasing member acts as an intermediary element between the first plate-like member and the second housing, absorbing and compensating for thermal deformation. This intermediary structure maintains the proper spacing and prevents direct contact, thereby protecting the variable nozzle mechanism from thermal effects.
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 stabilizes the holding structure of the variable nozzle unit, preventing pin sticking and reducing abrasion risks by controlling thermal deformation effects, ensuring a stable operation of the turbine.
Implementation Method 1
a biasing member that is disposed between the second housing and the first plate-like member and that is configured to bias the first plate portion toward a side of the gas flow path
Implementation Method 2
frictional resistance between the press-fitting pin and the press-fitting hole increases
Data Source
AI summary
This turbine comprises: a first housing that has a scroll passage; a first platelike member that includes an annular first plate; a second platelike member that includes an annular second plate forming a gas passage between the first plate and the second plate; a second housing that has a facing surface facing the back surface, of the first plate, on a side opposite to the gas passage across a first space; an annular member that is disposed in the first space and that rotates with respect to the first platelike member; a link member coupled at one end to the annular member and coupled at the other end to a variable nozzle vane; a positioning pin fitted at one end in a first hole formed in the back surface of the first plate and fitted at the other end in a second hole formed in the facing surface of the second housing; and a stopper configured such that a first gap is formed between the facing surface, or the first plate, and the stopper, and the first gap is smaller than a second gap between the annular member and the facing surface, and than a third gap between the link member and the facing surface.