TITLE OF THE INVENTION: AN IMPROVED VANE FOR VARIABLE TURBINE GEOMETRYTURBOCHARGERS
FILED OF THE INVENTION
This invention relates to a vane for variable turbine geometry turbochargers. More particularly, the present invention relates to an improved vane design that is applicable to aerodynamic vanes that are disposed within a variable geometry.
BACKGROUND OF THE INVENTION:
Turbochargers are widely used in internal combustion engines. They are a type of forced induction system. They deliver compressed air to the engine intake, allowing more fuel to be combusted, thus boosting the engine's horsepower without significantly increasing engine weight. Turbochargers use the exhaust flow from the engine to drive a turbine, which is mechanically connected to a compressor. Turbochargers, which utilize some form of turbine flow and pressure control are called by several names and offer control though various means. Some have rotating vanes, some have sliding sections or rings. Some titles for these devices are: Variable turbine geometry(VTG), Variable geometry turbine (VGT) variable nozzle turbine (VNT), or simply variable geometry (VG). VTG turbochargers utilize adjustable guide vanes that are rotatably connected to a pair of vane rings and/or the nozzle wall. These vanes are adjusted to control the exhaust gas backpressure and the turbocharger speed by modulating the exhaust gas flow to the turbine wheel. The efficiency of turbine in VTG turbocharger depends on various factors such as flow incidence angle at the turbine inlet, pressure drop across the guide vanes and uniformity of gas distribution entering the turbine.
Conventionally, there are different shapes of vanes that have been tried to achieve higher turbine efficiency. Some of the vanes used conventionally were found to yield lower turbine efficiency at all operating conditions, more predominantly, at lower operating conditions. The controllability is substandard due to undesired location of stagnation point on the conventional vanes. In few kinds of vanes, there is a possibility of local flow recirculation which leads to energy loss due to local pressure drop and affects the efficiency of the turbine.

US 7771162 discloses a specially shaped vane for the purpose of widening the operating window and maximizing flow efficiency within the turbocharger. To achieve the desired result, a planar introductory portion is provided on its surface for the purpose of helping to direct exhaust gas towards the turbine wheel, thereby to increase the aerodynamic efficiency of gas flow. But due to sudden change in profile, there may be flow recirculation just after the planar introductory portion which will cause local pressure drop, that affecting the overall efficiency of the turbine.
The vane disclosed in PCT/US2003/027529 is designed in an asymmetric shape in a way that the vane has been characterized as concave or convex relative to the interior to the vane and is defined by a continuous curve to increase the aerodynamic efficiency of gas flow. This vane consists of a gradual curve that starts at a point between about 5 to 40 percent of the initial vane length and gradually increases to a maximum point between about 40 to 80 percent of the initial vane length then gradually decreases back to zero at or before the end of the vane length. The flat portions near start of the vane length and end of the vane length are introduced to achieve positive torque due to increase in drag. Such a configuration requires flow over the vane to turn 2 to 3 times according to the vane profile. So, it requires flow to make atleast 2 turns to achieve desired efficiency along with positive torque. The first turn helps the vane to achieve positive torque and the second turn helps to divert the flow to desired direction. More number of turns in flow path can cause increase in drag over the vane, thus leading to local pressure drop and loss in efficiency.
The vane disclosed in US patent application number 12/812499 is designed such that the line of curvature of the guide vane has at least one or more than one sector having a discontinuous course to increase the aerodynamic efficiency of gas flow. The vane disclosed has at least one discontinuous section, this may leads to local flow recirculation near the discontinuity which will case local pressure drop, thereby affecting the overall efficiency of the turbine
There is therefore a need in the art for an improved turbocharger vane to overcome the above mentioned problems.

OBJECTIVES OF THE INVENTION
The present invention as embodied by an improved vane for variable turbine geometry turbocharger, succinctly fulfils the above-mentioned need(s) in the art. The present invention has objective(s) arising as a result of the above-mentioned need(s), said objective(s) being enumerated below. Inasmuch as the objective(s) of the present invention are enumerated, it will be obvious to a person skilled in the art that, the enumerated objective(s) are not exhaustive of the present invention in its entirety, and are enclosed solely for the purpose of illustration. Further, the present invention encloses within its scope and purview, any structural altemative(s) and/or any functional equivalent(s) even though, such structural alternative(s) and/or any functional equivalent(s) are not mentioned explicitly herein or elsewhere, in the present disclosure. The present invention therefore also encompasses, any improvisation(s)/modification(s) applied to the structural alternative(s)/functional alternative(s) within its scope and purview. The present invention may be embodied in other specific form(s) without departing from the spirit or essential attributes thereof.
An objective of the present invention is to provide an improved vane for variable turbine geometry turbocharger that yields higher turbine efficiency at all working conditions.
Another objective of the present invention is to provide an improved vane for variable turbine geometry turbocharger that has better controllability over the conventional vanes.
Yet another objective of the present invention is to provide an improved vane for variable turbine geometry turbocharger in which the efficiency of the turbine is increased by eliminating conventional local flow recirculation.
SUMMARY OF THE INVENTION
The present invention as embodied by an improved vane for variable turbine geometry turbocharger, succinctly fulfils the objective(s) of the present invention as broadly enumerated in the present disclosure. However, it would be perfectly clear to a person skilled in the art

that, inasmuch as the objectives have been enumerated, said objectives are only indicative of the scope and general coverage of the present invention.
Conventionally, a vane comprises two different edges-a leading edge and a trailing edge, two different lines- a first line that splits the vane into two parts and a second line that is a straight line that connects the leading edge with the trailing edge, two different airfoils- an outer airfoil associated with both the leading edge and the trailing edge and an inner airfoil associated with both the leading edge and the trailing edge, and has a certain radial thickness. The vane is rotated to open or close at different operating conditions about a pivot point. The first line and the second line of the vane may or may not intersect with each other.
An improved vane is characterized by one or more points of deflection and corresponding angles of deflection that split the vane into a plurality of sections, wherein the plurality of sections are continuous in nature. The one or more points of deflection can lie anywhere within the conventional vane.
The improved vane is formed by bending or rotating the trailing edge of the conventional vane towards the turbine wheel about every single point of deflection by a corresponding angle of deflection, wherein the angle of deflection is greater than 4° and less than 60°. This results in two portions being formed-a trailing edge portion and leading edge portion. After the trailing edge is rotated, the part of the trailing edge portion and the part of the leading edge portion falling near the bend are discarded and one or more arcs are constructed to join the leading edge portion and the trailing edge portion and complete the inner airfoil and the outer airfoil surfaces for the improved vane. The one or more arcs constructed on the inner airfoil and the outer airfoil are maintained tangential between the leading edge portion and the trailing edge portion for smooth flow of gas. The ratio of the length of leading edge portion and the length of second line, with respect to every single point of deflection is maintained between 0.1 and 0.9.
BRIEF DESCRIPTION OF THE DRAWINGS
The description of the present invention in conjunction with the drawings, illustrating the present invention and in application(s) illustrative of the present invention, explain in detail,

the working of the present invention. It will be amply clear to a person skilled in the art, that the application as disclosed in the drawings are merely illustrative of the scope of the present invention and not exhaustive of the scope of the present invention, in its entirety.
Figure 1 illustrates one embodiment of the conventional vane for turbocharger.
Figure 2 illustrates one embodiment of an improved vane for turbocharger in accordance with
the present invention.
Figure 3 illustrates the region of deflection, point of deflection and angle of deflection to form
the improved vane for turbocharger.
Figures 4(a), 4(b) and 4(c) illustrates some other embodiments of the improved vane for
turbocharger in accordance with the present invention with respect to different points of
deflections and different angles of deflections.
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of an existing vane (100) (described henceforth as "primary vane") is depicted in Figure 1. The primary vane (100) comprises two different edges-a leading edge (101) and a trailing edge (102), two different lines- a first line (105) that splits the vane into two parts and a second line (203) that is a straight line that connects the leading edge (101) with the trailing edge (102), two different airfoils- an outer airfoil (103) associated with both the leading edge (101) and the trailing edge (102) and an inner airfoil (104) associated with both the leading edge (101) and the trailing edge (102), and has a certain radial thickness (106). The primary vane (100) is rotated to open or close at different operating conditions about a pivot point (107). The first line (105) and the second line (203) of the primary vane (100) may or may not intersect with each other.
An improved vane is (200) depicted in Figures 2 and 3. The improved vane (200) is characterized by one or more points of deflection (201) and corresponding angles of deflection (202) that split the vane into a plurality of sections, wherein the plurality of sections are continuous in nature. The improved vane (200) can have a maximum of 3 points of deflections (201). The one or more points of deflection (201) can lie anywhere with the primary vane (100) or outside the primary vane (100).

The improved vane (200) is formed by bending or rotating the trailing edge (102) of the primary vane (100) towards the turbine wheel about every single point of deflection (201) by a corresponding angle of deflection (202), wherein the angle of deflection is greater than 4° and less than 60°, as illustrated in Figure 3. After the trailing edge (102) is rotated, the part of the trailing edge portion (206) and the part of the leading edge portion (205) falling near the bend (denoted by dotted lines in Figure 3) are discarded and one or more arcs are constructed to join the leading edge portion (205) and the trailing edge portion (206) and complete the inner airfoil (104) and the outer airfoil (105) surfaces for the improved vane (200). The one or more arcs constructed on the inner airfoil (104) and the outer airfoil (105) are maintained tangential between the leading edge portion (205) and the trailing edge portion (206) for smooth flow of gas. The region where the bend or rotation takes place in the improved vane (200) is illustrated as a region of deflection (204) in Figure 3.
The improved vane (200) in different embodiments with different points of deflection (201) and different angles of deflection (202) are illustrated in Figures 4(a), 4(b) and 4(c). The length from the point of deflection (201) to the leading edge (101) is illustrated as (207) and the length from point of deflection (201) to the trailing edge (202) is (208). The ratio of the length from point of deflection (201) to the leading edge (101), and the length of the second line (203), with respect to every single point of deflection (201) is maintained between 0.1 and 0.9. The length from the point of deflection (201) to the leading edge (101), and the length from point of deflection (201) to the trailing edge (102) should be greater than or equal to 2mm. In the improved vane (200), the first line and the second line do not intersect at all. Further, the first line of the improved vane is not a continuous curve; it can be any combination of continuous sections such as "straight line - arc - straight line" or "arc-arc-straight line". Further, the vane (200) described and illustrated in Figures 2 and 3 is derived from a symmetric vane. But, the concept explained herein can also be applied to asymmetric vanes as well. Moreover, the leading edge portion (205) and trailing edge portion (206) required to create the improved vane airfoil can be borrowed even from different primary vanes.
It will be apparent to a person skilled in the art that the above description is for illustrative purposes only and should not be considered as limiting. Various modifications, additions,

alterations, and improvements without deviating from the spirit and the scope of the invention may be made by a person skilled in the art.
ADVANTAGES
The improved vane has a lower turbine inlet flow angle and lower pressure drop when compared with the primary vane and thus has a higher efficiency. Greater controllability can be achieved by adjusting the one or more points of deflection and corresponding angles of deflection. The improved vane has no local flow recirculation problem and thus the efficiency of the turbine is high.
We claim:
1. An improved vane obtained from a primary vane, comprising:
a. a leading edge and a trailing edge;
b. a first line that splits the vane into two parts;
c. a second line that is a straight line that connects the leading edge with the
trailing edge, wherein the second line may intersect with the first line;
d. an outer airfoil associated with both the leading edge and the trailing edge;
and
e. an inner airfoil associated with both the leading edge and the trailing edge,
characterized in that
the improved vane is split about one or more points of deflection by a corresponding angle of deflection into a plurality of sections, wherein:
f. the trailing edge is bent or rotated towards the turbine wheel about every
single point of deflection by the corresponding angle of deflection to form a
leading edge portion and a trailing edge portion, wherein the angle of
deflection is greater than 4° and less than 60°;
g. the ratio of the length from the point of deflection to the leading edge, and the
length of the second line, with respect to every single point of deflection is
greater than 0.1 and less than 0.9;
h. the improved vane has one or more arcs that are constructed to join the leading edge portion and the trailing edge portion and to facilitate a smooth and tangential transition between the leading edge portion and the trailing edge portion;
i. the first line does not intersect with the second line; and
j. the plurality of sections are continuous.
2. An improved vane as claimed in claim 1, wherein the one or more points of deflection can lie anywhere within the primary vane.
3. An improved vane as claimed in claim 1, wherein the one or more points of deflection can lie anywhere outside the primary vane.

4. An improved vane as claimed in claim 1, wherein the length from the point of deflection (201) to the leading edge is greater than or equal to 2mm.
5. An improved vane as claimed in claim 1, wherein the length from the point of deflection (201) to the trailing edge is greater than or equal to 2mm.
6. An improved vane as claimed in claim 1, wherein the vane can have maximum 3 point of deflections.