WO2016035329A1 - Exhaust turbine for turbocharger - Google Patents

Abstract

In the present invention, different attack angles are set for turbine blades (22) on one side and on the other side in an axial direction in accordance with a relative inflow angle of exhaust gas. In other words, a first attack angle (θ1) is set on the one side in the axial direction in accordance with the relative inflow angle of exhaust gas blown to the turbine blades through a first scroll passage (19a), and a second attack angle (θ2) is set on the other side in the axial direction in accordance with the relative inflow angle of exhaust gas blown to the turbine through a second scroll passage (19b).

Description

Turbocharger exhaust turbine Cross-reference of related applications

This application is based on Japanese Patent Application No. 2014-180610 filed on September 4, 2014 and Japanese Application No. 2015-168824 filed on August 28, 2015. Is used.

The present disclosure relates to an exhaust turbine of a turbocharger having two scroll passages with different capacities.

Patent Document 1 is known as a prior art related to an exhaust turbine of a turbocharger.

The exhaust turbine disclosed in the same document 1 divides the inside of the turbine housing in the axial direction by a partition wall to form a first scroll channel having a small channel area and a second scroll channel having a large channel area, In addition, a variable capacity valve that can open and close the inlet of the second scroll flow path is provided.

In this exhaust turbine, for example, the variable displacement valve is closed in a low speed rotation region of the engine (for example, when the exhaust gas flow rate is small), and exhaust gas is intensively introduced only into the first scroll flow path. In many high-speed rotation regions, the turbine output corresponding to the exhaust gas flow rate can be obtained by opening the variable displacement valve and introducing the exhaust gas into the second scroll flow path.

JP 58-138222 A

However, in the exhaust turbine of Patent Document 1, the flow area of the first scroll flow path is different from that of the second scroll flow path. Specifically, the flow area of the first scroll flow path is 1/3 or less of the entire area. It is. In this configuration, two different flow and velocity vectors are generated in the axial direction at the inlet of the turbine blade, and the angle of the exhaust gas flow flowing into the turbine blade is also different. As a result of detailed studies by the inventors, if the turbine blades are designed for the case where exhaust gas is introduced into both the first scroll passage and the second scroll passage, the exhaust gas is introduced only into the first scroll passage. In this case, turbulent flow or choke is generated, and the pressure loss is increased, so that the problem that turbine efficiency is lowered has been found. Further, the inventor has a problem in that the first scroll flow path with a small flow path area increases the friction loss on the flow path surface as compared with the second scroll flow path with a large flow path area, so that the turbine efficiency decreases. Was also found.

An object of the present disclosure is to provide an exhaust turbine of a turbocharger that can suppress a decrease in turbine efficiency.

In one aspect of the present disclosure, an exhaust turbine of a turbocharger includes a turbine wheel having a plurality of turbine blades around a hub fixed to a shaft, and a turbine housing that forms a scroll passage on an outer periphery of the turbine wheel, As the exhaust gas discharged from the internal combustion engine is blown to the turbine blades through the scroll passage, the turbine wheel rotates, and the turbine housing divides the scroll passage into one side and the other side in the axial direction. The first scroll flow path is formed on the side, the second scroll flow path is formed on the other side, and the exhaust gas flow rate blown to the turbine blades through the first scroll flow path passes through the second scroll flow path to the turbine. It is set to be smaller than the exhaust gas flow rate blown to the blade, and corresponds to the first scroll flow path at the inlet of the turbine blade. The angle of attack of the turbine blade set on one side of the direction is called the first angle of attack, and the angle of attack of the turbine blade set on the other side in the axial direction corresponding to the second scroll flow path is the second angle of attack. When the exhaust gas inflow angle flowing into the turbine blade inlet when the radial direction is 0 ° in the rotational coordinate system of the turbine wheel is defined as a relative inflow angle, the first angle of attack is It is set according to the relative inflow angle of the exhaust gas blown to the turbine blade through the scroll flow path, and the second angle of attack is the relative inflow angle of the exhaust gas blown to the turbine blade through the second scroll flow path. Set accordingly.

In the exhaust turbine of the present disclosure, the flow rate of the exhaust gas blown to the turbine blade through the first scroll flow path is set smaller than the flow rate of the exhaust gas blown to the turbine blade through the second scroll flow path. For this reason, the relative inflow angle of the exhaust gas differs between one axial side corresponding to the first scroll passage and the other axial side corresponding to the second scroll passage at the inlet of the turbine blade.

In contrast, in the turbine blade, different angles of attack are set on the one side and the other side in the axial direction according to the relative inflow angle of the exhaust gas. That is, on one side in the axial direction, the first angle of attack is set according to the relative inflow angle of the exhaust gas blown to the turbine blades through the first scroll flow path, and on the other side in the axial direction, the second scroll The second angle of attack is set according to the relative inflow angle of the exhaust gas blown to the turbine blade through the flow path. Thus, when the exhaust gas flow rate passing through the first scroll flow path is different from the exhaust gas flow rate passing through the second scroll flow path, the conventional turbine disclosed in Patent Document 1 that designs the turbine blades in accordance with either one of the exhaust gas flow rates. Compared with technology, the design freedom of turbine blades is improved.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing
FIG. 1 is a perspective view of a turbine wheel according to a first embodiment of the present disclosure; FIG. 2 is a cross-sectional view showing a first angle of attack and a second angle of attack set on the turbine blade, FIG. 3 is a cross-sectional view of the exhaust turbine according to the first embodiment. FIG. 4 is an overall configuration diagram showing an intake / exhaust system of an engine including a turbocharger, FIG. 5 is an explanatory view showing a speed triangle of exhaust gas, FIG. 6 is an explanatory diagram showing the relationship between the first angle of attack and the second angle of attack, FIG. 7 is a perspective view of a turbine blade according to a second embodiment of the present disclosure; FIG. 8 is a cross-sectional view of an exhaust turbine according to a third embodiment of the present disclosure, FIG. 9 is a cross-sectional view of an exhaust turbine according to Example 4 of the present disclosure; FIG. 10 is a cross-sectional view of the exhaust turbine according to the fifth embodiment of the present disclosure.

The mode for carrying out the present disclosure will be described in detail with reference to the following examples.
[Example 1]
As shown in FIG. 4, the turbocharger 1 according to the first embodiment includes an exhaust turbine 4 disposed on the downstream side of the exhaust manifold 3 in the exhaust path of the engine 2, and an upstream side of the intake manifold 5 in the intake path of the engine 2. And an intake air compressor 6 disposed in the.

The exhaust turbine 4 includes a turbine housing 7 that introduces exhaust gas through the exhaust manifold 3 and a turbine wheel 8 that is housed inside the turbine housing 7 and converts the kinetic energy of the exhaust gas into rotational force. The turbine wheel 8 is a radial turbine that discharges exhaust gas flowing in from the outer periphery in the radial direction in the axial direction.

In the exhaust path downstream of the exhaust turbine 4, an exhaust purification device 9 that removes harmful substances contained in the exhaust gas, a muffler 10 that is a silencer, and the like are disposed.

The exhaust turbine 4 is provided with a waste gate mechanism that can adjust the flow rate of exhaust gas flowing into the turbine wheel 8. The waste gate mechanism includes, for example, an exhaust bypass passage 11 that connects the exhaust upstream side and the exhaust downstream side of the turbine housing 7 to bypass the turbine wheel 8, and a waste gate valve 12 that can open and close the exhaust bypass passage 11. The waste gate valve 12 opens when the pressure of the air sent to the engine 2 (supercharging pressure) exceeds a certain value. When the waste gate valve 12 is opened, a part of the exhaust gas flows to the downstream side of the turbine wheel 8 through the exhaust bypass passage 11, and thus the supercharging pressure is reduced by reducing the flow rate of the exhaust gas hitting the turbine wheel 8. I can control it. The waste gate mechanism may be a built-in type in which an exhaust bypass passage 11 is formed in the turbine housing 7 and a waste gate valve 12 is incorporated, or an external type configured independently of the exhaust turbine 4.

The intake compressor 6 includes a compressor wheel 14 connected to the turbine wheel 8 via the turbine shaft 13 and a compressor housing 15 that houses the compressor wheel 14 therein. When the compressor wheel 14 is rotated by the rotation of the turbine wheel 8, the intake compressor 6 compresses the air introduced into the compressor housing 15 and forcibly feeds it into the engine 2.

An air cleaner 16 that filters air taken in by the engine 2 is provided in the intake path upstream of the intake compressor 6. On the other hand, an intercooler 17 that cools the air compressed by the intake compressor 6 is disposed in the intake path downstream of the intake compressor 6, and an electronic throttle device 18 that adjusts the intake air amount downstream of the intercooler 17 and the like. Is disposed.

Subsequently, features of the exhaust turbine 4 according to the present disclosure will be described.

The turbine housing 7 has a spiral scroll passage 19 formed on the outer periphery of the turbine wheel 8, and as shown in FIG. 3, the scroll passage 19 is separated by a partition wall 7a on one side and the other side in the axial direction (left-right direction in the drawing). It is divided into and. When one side of the scroll channel 19 divided by the partition wall 7a is called the first scroll channel 19a and the other side is called the second scroll channel 19b, the first scroll channel 19a is more than the second scroll channel 19b. The capacity is small. In the present disclosure, the side opposite to the direction in which the exhaust gas flows out from the turbine wheel 8 (the left side in the figure) is defined as one side in the axial direction, and the same side as the direction in which the exhaust gas flows out (the right side in the figure) is the axial direction. It is defined as the other side.

A variable capacity valve 20 (see FIG. 4) that varies the capacity of the exhaust turbine 4 by adjusting the flow rate of the exhaust gas introduced into the second scroll flow path 19b is disposed at the inlet of the second scroll flow path 19b. The The variable displacement valve 20 is controlled in valve opening according to the operating state of the engine 2. For example, the valve opening is controlled to be small during low speed and low load operation, and the valve opening is controlled to be large during high speed and high load operation. When the variable displacement valve 20 is closed and the inlet of the second scroll passage 19b is closed, the exhaust gas discharged from the engine 2 is introduced only into the first scroll passage 19a, and the variable displacement valve 20 is opened. When the inlet of the second scroll channel 19b is opened, exhaust gas is introduced into both the first scroll channel 19a and the second scroll channel 19b. In the present embodiment, the variable capacity valve 20 is a flow rate adjusting unit.

As shown in FIG. 1, the turbine wheel 8 includes a hub 21 fixed to the turbine shaft 13 (see FIG. 4) and a plurality of turbine blades 22 provided around the hub 21.

The hub 21 is provided such that the hub radius, which is a height in the radial direction perpendicular to the axial center of the turbine wheel 8, decreases in a quadratic curve from the inlet side to the outlet side of the exhaust gas with respect to the turbine wheel 8. .

The turbine blades 22 have different angles of attack on one side in the axial direction corresponding to the first scroll flow path 19a and on the other side in the axial direction corresponding to the second scroll flow path 19b.

As shown in FIG. 2, the angle of attack is an angle formed by the front edge direction and the reference line. 2 shows a cross-sectional shape along the longitudinal direction of the turbine blade 22 and corresponds to the IIa-IIa cross section and the IIb-IIb cross section of FIG. The leading edge direction is a direction in which a curve of a blade thickness center line (a line indicated by a one-dot chain line in FIG. 2) in a cross section along the longitudinal direction of the turbine blade 22 extends in the outer diameter direction at the blade tip. In other words, the leading edge direction is the direction of the tangent to the center line at the blade tip. Hereinafter, the blade end on the inlet side of the turbine blade 22 is referred to as a leading edge 22a. The reference line is a line extending in the radial direction of the turbine wheel 8 through the leading edge 22a.

In the following description, the angle of attack set on one side in the axial direction is referred to as a first angle of attack θ1, and the angle of attack set on the other side in the axial direction is referred to as a second angle of attack θ2.

The angle of attack of the turbine blade 22 is set corresponding to the relative inflow angle of the exhaust gas blown to the turbine blade 22. That is, the first angle of attack θ1 is set according to the relative inflow angle of the exhaust gas blown to the turbine blades 22 from the first scroll channel 19a, and the second angle of attack θ2 is determined from the second scroll channel 19b. It is set according to the relative inflow angle of the exhaust gas blown to the turbine blade 22.

The relative exhaust gas inflow angle is an inflow angle of exhaust gas flowing into the inlet of the turbine blade 22 when the radial direction is set to 0 ° in the rotating coordinate system of the turbine wheel 8. That is, the angle β formed by the relative velocity vector and the reference line in the velocity triangle shown in FIG. Further, c represents the absolute speed of the exhaust gas, u represents the peripheral speed of the turbine blade 22, and w represents the relative speed of the exhaust gas.

Here, the angle of attack of the turbine blade 22 with respect to the relative inflow angle β (see FIG. 5A) when the relative speed w has a vector in the rotational direction of the turbine wheel 8 with respect to the reference line (the arrow direction in the figure). Expressed as a positive angle. On the other hand, the angle of attack of the turbine blade 22 with respect to the relative inflow angle β (see FIG. 5B) when the relative speed w has a vector in the counter-rotating direction of the turbine wheel 8 with respect to the reference line is expressed as a negative angle.

In the present disclosure, when a positive angle and a negative angle are compared, it is defined that the angle of attack having a positive angle is larger than the angle of attack having a negative angle, not the size of the angle itself. For example, at +10 degrees and -30 degrees, +10 degrees is greater.

Based on the above definition, the turbine blade 22 of the present disclosure is formed such that the average value of the first angle of attack θ1 is larger than the average value of the second angle of attack θ2.

Several modes in which the average value of the first angle of attack θ1 is larger than the average value of the second angle of attack θ2 will be described with reference to FIG. When the arrow direction shown in the figure is the rotational direction of the turbine wheel 8, the left side in the figure is a positive angle and the right side in the figure is a negative angle from the reference line.

(A) of the figure shows the case where the average value of the first angle of attack θ1 and the average value of the second angle of attack θ2 are both positive.

FIG. 5B shows a case where the average value of the first angle of attack θ1 and the average value of the second angle of attack θ2 both have negative angles, and the average value of the first angle of attack θ1 is the first value. The negative angle is smaller than the average value of the two angle of attack θ2, that is, the average value of the first angle of attack θ1 is larger than the average value of the second angle of attack θ2.

FIG. 5C shows the case where the average value of the first angle of attack θ1 has a positive angle and the average value of the second angle of attack θ2 is zero.

FIG. 4D shows the case where the average value of the first angle of attack θ1 is zero and the average value of the second angle of attack θ2 is a negative angle.

FIGS. 4E to 4G show the case where the average value of the first angle of attack θ1 has a positive angle and the average value of the second angle of attack θ2 has a negative angle. The average value of the first angle of attack θ1 that is an angle of the second angle is larger than the average value of the second angle of attack θ2 that is a negative angle. In the case of (f) in the figure, the average value of the first angle of attack θ1 is the first angle of attack θ1 in the magnitude relationship between the average value of the first angle of attack θ1 and the average value of the second angle of attack θ2. Although the average value of the first angle of attack θ1 having a positive angle is smaller than the average value of the angle of attack θ2 of 2 (θ1 <θ2), the second angle of attack has a negative angle. It is larger than the average value of the angle θ2.

An example corresponding to the above figure (e) is shown in FIG. 1 and FIG.

In the turbine blade 22 shown in FIG. 1, the leading edge 22a is formed in a substantially straight line on one side (the lower side in the drawing) and the other side in the axial direction, and as shown in FIG. The first angle of attack θ1 having a larger angle is formed larger than the second angle of attack θ2 having a negative angle. In addition, the arrow attached | subjected to FIG. 1, FIG. 2 has shown the rotation direction of the turbine wheel 8. FIG.

Also, the first angle of attack θ1 and the second angle of attack θ2 do not change clearly between one side and the other side in the axial direction, but change smoothly. That is, there is an angle of attack of zero angle between the one side and the other side in the axial direction, and the first angle of attack θ1 is on the one side in the axial direction from the angle of attack of zero angle to the hub side of the leading edge 22a. The second angle of attack θ2 is gradually decreased toward the opposite hub side of the leading edge 22a (negative angle is gradually increased) on the other side in the axial direction. Accordingly, it can be said that the turbine blade 22 shown in FIG. 1 is formed such that the average value of the first angle of attack θ1 having a positive angle is larger than the average value of the second angle of attack θ2 having a negative angle.

In the exhaust turbine 4 of the first embodiment, the first scroll passage 19a is formed to have a smaller capacity than the second scroll passage 19b. For this reason, the relative inflow angle of the exhaust gas is different at the inlet of the turbine blade 22 between the one axial side corresponding to the first scroll passage 19a and the other axial side corresponding to the second scroll passage 19b. On the other hand, the turbine blade 22 has different angles of attack depending on the relative inflow angles on one side and the other side in the axial direction. Specifically, the first angle of attack θ1 is set on one side in the axial direction, the second angle of attack θ2 is set on the other side in the axial direction, and the average value of the first angle of attack θ1 is the second angle of attack. It is larger than the average value of the angle θ2. Thereby, since the angle of attack suitable for the relative inflow angle can be set on each of the one side and the other side in the axial direction, the flow along the turbine blades 22 is increased as compared with the prior art of Patent Document 1, and thus the turbine The separation loss in the wheel 8 is suppressed, and the turbine efficiency can be increased.

The turbine blade 22 has a leading edge 22a formed substantially linearly on one side and the other side in the axial direction, and the second scroll channel on one side in the axial direction corresponding to the first scroll channel 19a. The angle of attack is larger than the other side in the axial direction corresponding to 19b. That is, since the average value of the first angle of attack θ1 is larger than the average value of the second angle of attack θ2, the average value of the first angle of attack θ1 is smaller than the average value of the second angle of attack θ2. Compared with the case, the manufacture of the turbine blade 22 is easier.

The turbine blade 22 has an angle of attack of zero angle between one side and the other side in the axial direction, and the first angle of attack θ1 gradually increases on one side in the axial direction across the angle of attack of zero angle. The second angle of attack θ2 is gradually reduced on the other side in the axial direction. That is, since the first angle of attack θ1 and the second angle of attack θ2 are smoothly changed across the angle of attack of zero angle, it is possible to provide a turbine blade 22 that is less stress concentrated and easy to manufacture. . Moreover, since the angle of attack changes smoothly, the flow of exhaust gas also becomes smooth, which contributes to the improvement of turbine efficiency.

Hereinafter, other examples according to the present disclosure will be described.

It should be noted that parts that are the same as those in the first embodiment and that indicate the same configuration are denoted by the same reference numerals as those in the first embodiment, and redundant description is omitted.

[Example 2]
As shown in FIG. 7, the second embodiment is an example in which the leading edge 22a of the turbine blade 22 is shifted in the circumferential direction between one axial side (the lower side in the drawing) and the other side. Specifically, the circumferential position of the leading edge 22a is formed on the counter-rotation direction side on one side in the axial direction having the first angle of attack θ1 and on the other side in the axial direction having the second angle of attack θ2. The Note that the average value of the first angle of attack θ1 is set larger than the average value of the second angle of attack θ2, as in the first embodiment.

According to the above configuration, since the first angle of attack θ1 and the second angle of attack θ2 clearly change between one side and the other side in the axial direction, the average of the first angle of attack θ1 The angle difference between the value and the average value of the second angle of attack θ2 can be made larger.

Example 3
The third embodiment is an example in which a partition plate 23 is provided on the turbine blade 22 as shown in FIG.

The partition plate 23 has an exhaust gas on one side blown to the turbine blades 22 through the first scroll flow path 19a and an exhaust gas on the other side blown to the turbine blades 22 through the second scroll flow path 19b. Provided to be an independent flow. That is, the turbine blades 22 adjacent in the circumferential direction are extended from the leading edge 22a to the trailing edge 22b. The trailing edge 22b refers to the blade end portion on the outlet side of the turbine blade 22.

Thereby, interference between the exhaust gas on one side and the exhaust gas on the other side can be reduced, and the diffusion of the exhaust gas between the one side and the other side can be suppressed, so that the turbine efficiency is improved. Moreover, the effect of the reinforcement rib with respect to the turbine blade 22 can also be expected by providing the partition plate 23.

Example 4
As shown in FIG. 9, the fourth embodiment is an example in which fixed nozzles are arranged at the outlets of the first scroll flow path 19a and the second scroll flow path 19b. Example 2 can be applied.

The fixed nozzle includes a first fixed nozzle 24 disposed at the outlet of the first scroll passage 19a and a second fixed nozzle 25 disposed at the outlet of the second scroll passage 19b. A nozzle plate 26 is disposed between the fixed nozzle 24 and the second fixed nozzle 25. That is, the first fixed nozzle 24 is disposed on one side in the axial direction with the nozzle plate 26 interposed therebetween, and the second fixed nozzle 25 is disposed on the other side in the axial direction. The nozzle plate 26 is arranged so that the exhaust gas passing through the first fixed nozzle 24 and the exhaust gas passing through the second fixed nozzle 25 flow independently of each other. A space with the fixed nozzle 25 is partitioned in the axial direction.

In the first fixed nozzle 24 and the second fixed nozzle 25, a plurality of nozzle vanes are arranged in the circumferential direction with a predetermined interval, and the throat area of the first fixed nozzle 24 is the second fixed nozzle. The throat area is smaller than 25. The throat area is a minimum flow path area formed between nozzle vanes adjacent in the circumferential direction. For example, the first fixed nozzle 24 has more nozzle vanes than the second fixed nozzle 25, or The throat area can be reduced by increasing the inclination of the nozzle vane with respect to the radial direction. As a result, the exhaust gas flow rate passing through the first fixed nozzle 24 is less than the exhaust gas flow rate passing through the second fixed nozzle 25.

According to the above configuration, since the exhaust gas flow rate is reduced by the first fixed nozzle 24 and the second fixed nozzle 25, the capacity of the first scroll channel 19a is made smaller than the capacity of the second scroll channel 19b. do not have to. In other words, the first scroll channel 19a and the second scroll channel 19b can be formed to have the same capacity. Thereby, compared with the case where the capacity | capacitance of the 1st scroll flow path 19a is made small, since the friction loss resulting from the surface roughness of the turbine housing 7 can be reduced, turbine efficiency improves.

Further, since the nozzle plate 26 is disposed between the first fixed nozzle 24 and the second fixed nozzle 25, the exhaust gas that passes through the first fixed nozzle 24 and the second fixed nozzle 25 pass through. The first fixed nozzle 24 and the second fixed nozzle 25 can form independent flows without interfering with the exhaust gas.

Example 5
The fifth embodiment is an example in which the turbine radius differs between a portion corresponding to the first scroll passage 19a and a portion corresponding to the second scroll passage 19b of the turbine blade 22. The turbine radius refers to the distance from the axial center of the turbine wheel 8 to the leading edge 22a of the turbine blade 22 indicated by a one-dot chain line in FIG.

Hereinafter, the specific configuration of Example 5 is shown in FIG.

The turbine blade 22 has a large turbine radius on one side in the axial direction corresponding to the first scroll flow path 19a, and a small turbine radius on the other side in the axial direction corresponding to the second scroll flow path 19b. That is, when the turbine radius of the part corresponding to the first scroll flow path 19a is the first radius r1, and the turbine radius of the part corresponding to the second scroll flow path 19b is the second radius r2, as shown in FIG. The relationship that one radius r1 is larger than the second radius r2 is established.

With the above-described configuration, the exhaust gas at the inlet of the turbine blade 22 on one side in the axial direction corresponding to the first scroll passage 19a and on the other side in the axial direction corresponding to the second scroll passage 19b. The relative inflow angle can be made closer. As a result, generation of turbulent flow or choke can be further suppressed than in the above-described embodiments, and separation loss in the turbine wheel 8 can be suppressed, so that turbine efficiency can be improved.

[Modification]
In the first embodiment, the first scroll channel 19a is formed on one side in the axial direction and the second scroll channel 19b is formed on the other side in the axial direction. However, the first scroll channel 19a and the second scroll are formed. It is also possible to apply the present disclosure to a configuration in which the flow path 19b is arranged in reverse. In this case, the turbine blade 22 has a second angle of attack θ2 set on one side in the axial direction and a first angle of attack θ1 set on the other side in the axial direction, but the average of the first angle of attack θ1 The value is set larger than the average value of the second angle of attack θ2 as in the first embodiment.

Further, the present disclosure can be applied even if the first scroll channel 19a and the second scroll channel 19b have the same size and positional relationship. In this case, it is possible to correct the difference in inflow angle due to manufacturing variations.

In the fourth embodiment, the throat area of the first fixed nozzle 24 arranged on one side in the axial direction is smaller than that of the second fixed nozzle 25 arranged on the other side in the axial direction. The present disclosure can be applied to a configuration in which the throat area of the second fixed nozzle 25 is smaller than that of the fixed nozzle 24. In this case, the turbine blade 22 has a first angle of attack θ1 set on the other axial side corresponding to the second fixed nozzle 25 having a small throat area, and corresponds to the first fixed nozzle 24 having a large throat area. A second angle of attack θ2 is set on one side in the axial direction. Further, the average value of the first angle of attack θ1 is set larger than the average value of the second angle of attack θ2, as in the first embodiment.

Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims (11)

A turbine wheel (8) having a plurality of turbine blades (22) around a hub (21) fixed to the shaft (13);
A turbine housing (7) forming a scroll channel (19) on the outer periphery of the turbine wheel (8),
An exhaust turbine of a turbocharger in which the turbine wheel (8) rotates when exhaust gas discharged from an internal combustion engine (2) is blown to the turbine blades (22) through the scroll flow path (19). ,
The turbine housing (7) divides the scroll channel (19) into one side and the other side in the axial direction, the first scroll channel (19a) on the one side, and the second scroll flow on the other side. The exhaust gas flow rate that forms the passage (19b) and is blown to the turbine blade (22) through the first scroll passage (19a) passes through the second scroll passage (19b). Set to be smaller than the exhaust gas flow rate blown to the turbine blade (22),
The angle of attack of the turbine blade (22) set at one side in the axial direction corresponding to the first scroll channel (19a) at the inlet of the turbine blade (22) is defined as a first angle of attack (θ1). The angle of attack of the turbine blade (22) set on the other side in the axial direction corresponding to the second scroll channel (19b) is referred to as a second angle of attack (θ2), and the turbine wheel (8 ) In the rotating coordinate system, the inflow angle of the exhaust gas flowing into the inlet of the turbine blade (22) when the radial direction is 0 ° is defined as a relative inflow angle,
The first angle of attack (θ1) is set according to a relative inflow angle (β) of exhaust gas blown to the turbine blade (22) through the first scroll passage (19a), and the second The exhaust angle of the turbocharger is set according to the relative inflow angle (β) of the exhaust gas blown to the turbine blades (22) through the second scroll flow path (19b). The exhaust gas turbine of the turbocharger according to claim 1,
The turbine blade (22) is an exhaust turbine of a turbocharger in which an average value of the first angle of attack (θ1) and an average value of the second angle of attack (θ2) are different. The turbocharger exhaust turbine according to claim 1 or 2,
When a reference line is taken in the radial direction of the turbine wheel (8) and the relative speed of exhaust gas at the inlet of the turbine blade (22) has a vector in the rotational direction of the turbine wheel (8) with respect to the reference line The angle of attack of the turbine blade (22) set according to the relative inflow angle (β) is expressed as a positive angle, and the relative speed of the exhaust gas is counter-rotated by the turbine wheel (8) with respect to the reference line. When the angle of attack of the turbine blade (22) set according to the relative inflow angle (β) when the vector is in the direction is expressed as a negative angle, the average of the first angle of attack (θ1) An exhaust turbine of a turbocharger whose value is greater than an average value of the second angle of attack (θ2). The exhaust gas turbine of the turbocharger according to any one of claims 1 to 3,
When the tip of the turbine blade (22) to which the exhaust gas is blown is called a leading edge (22a), the leading edge (22a) is provided in a straight line, and between the one side and the other side in the axial direction. An exhaust turbine of a turbocharger in which the angle of attack (θ1, θ2) changes smoothly. The exhaust gas turbine of the turbocharger according to any one of claims 1 to 3,
When a tip end of the turbine blade (22) to which exhaust gas is blown is called a leading edge (22a), a turbocharger in which the circumferential position of the leading edge (22a) is different on one side and the other side in the axial direction. Exhaust turbine. The exhaust gas turbine of the turbocharger according to any one of claims 1 to 5,
The turbine blade (22) is an exhaust of a turbocharger having an average value of the first angle of attack (θ1) having a positive angle and an average value of the second angle of attack (θ2) having a negative angle. Turbine. The exhaust gas turbine of the turbocharger according to any one of claims 1 to 6,
The flow of exhaust gas blown to the turbine blade (22) through the first scroll passage (19a) and the exhaust gas blown to the turbine blade (22) through the second scroll passage (19b) An exhaust turbine of a turbocharger in which a partition plate (23) is provided between the turbine blades (22) adjacent in the circumferential direction so as to be independent from each other. The exhaust gas turbine of the turbocharger according to any one of claims 1 to 7,
When the side opposite to the direction in which the exhaust gas flows out from the turbine wheel (8) is defined as one side in the axial direction, and the same side as the direction in which the exhaust gas flows out is defined as the other side in the axial direction,
Exhaust of a turbocharger having a smaller capacity in the first scroll channel (19a) formed on one side in the axial direction than in the second scroll channel (19b) formed on the other side in the axial direction. Turbine. The exhaust gas turbine of the turbocharger according to any one of claims 1 to 8,
When the side opposite to the direction in which the exhaust gas flows out from the turbine wheel (8) is defined as one side in the axial direction, and the same side as the direction in which the exhaust gas flows out is defined as the other side in the axial direction,
A first fixed nozzle (24) arranged at the outlet of the first scroll flow path (19a) formed on one side in the axial direction to restrict the exhaust gas flow rate;
A second fixed nozzle (25) that is disposed at an outlet of the second scroll passage (19b) formed on the other side in the axial direction and throttles an exhaust gas flow rate;
The turbocharger exhaust turbine in which the first fixed nozzle (24) has a smaller throat area than the second fixed nozzle (25). The exhaust gas turbine of the turbocharger according to any one of claims 1 to 9,
The tip of the turbine blade (22) to which the exhaust gas is blown is called a leading edge (22a), and the distance from the axial center of the turbine wheel (8) to the leading edge (22a) of the turbine blade (22) When calling the turbine radius (r1, r2),
The turbine blade (22) has a large turbine radius (r1) on one axial side corresponding to the first scroll channel (19a), and an axis corresponding to the second scroll channel (19b). An exhaust turbine of a turbocharger in which the turbine radius (r2) is formed small on the other side in the direction. The exhaust gas turbine of the turbocharger according to any one of claims 1 to 10,
An exhaust turbine of a turbocharger having a flow rate adjusting part (20) capable of adjusting an exhaust gas flow rate introduced into the second scroll flow path (19b).

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