JP7491151B2 - Turbochargers and turbochargers - Google Patents

Description

This disclosure relates to turbines and turbochargers.

As a turbine provided in a turbocharger or the like, there is a turbine in which a turbine scroll passage communicating with an accommodating section that accommodates a turbine wheel is wound radially outwardly around the turbine wheel. In such a turbine, a tongue portion is provided at a position facing the downstream end of the turbine scroll passage. For example, Patent Document 1 discloses a double scroll type turbine equipped with two turbine scroll passages. In a double scroll type turbine, two tongue portions are formed between the two turbine scroll passages.

JP 2016-132996 A

The greater the distance (gap) between the tongue and the turbine wheel, the more likely it is that exhaust gas will leak into the turbine scroll passage without being sent to the turbine wheel. On the other hand, the smaller the distance between the tongue and the turbine wheel, the greater the excitation force acting on the turbine wheel, and the more likely it is that blade vibration will increase. Therefore, with conventional turbines, it was difficult to simultaneously reduce turbine wheel blade vibration and suppress exhaust gas leakage.

The objective of this disclosure is to provide a turbine and turbocharger that can suppress the leakage flow of exhaust gas while reducing the blade vibration of the turbine wheel.

In order to solve the above problems, the turbine of the present disclosure comprises a housing section that houses the turbine wheel, a turbine scroll passage wound radially outwardly around the turbine wheel and communicating with the housing section, and a tongue section that is provided at a position facing the downstream end of the turbine scroll passage, partitioning the turbine scroll passage, and in the section facing the turbine wheel, at least one end section in the rotational shaft direction of the turbine wheel is recessed radially outwardly from the turbine wheel with respect to a central section in the rotational shaft direction , and in the section of the tongue section facing the turbine wheel, the central section in the rotational shaft direction is closer to the turbine wheel than at least one end section .

In the portion of the tongue facing the turbine wheel, both ends in the rotational axis direction are recessed radially outward from the turbine wheel relative to the central portion in the rotational axis direction , and the central portion in the rotational axis direction may be closer to the turbine wheel than other portions .

To solve the above problem, the turbocharger disclosed herein is equipped with the above turbine.

According to the present disclosure, it is possible to suppress the leakage flow of exhaust gas while reducing the blade vibration of the turbine wheel.

FIG. 1 is a schematic cross-sectional view showing a turbocharger according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view taken along line AA of FIG. FIG. 3 is a cross-sectional view taken along line BB of FIG.

One embodiment of the present disclosure will be described below with reference to the attached drawings. The dimensions, materials, and other specific values shown in the embodiment are merely examples for ease of understanding, and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid duplicated explanations, and elements not directly related to the present disclosure are not illustrated.

1 is a schematic cross-sectional view showing a turbocharger TC according to an embodiment of the present disclosure. In the following description, the direction of arrow L shown in FIG. 1 is the left side of the turbocharger TC. The direction of arrow R shown in FIG. 1 is the right side of the turbocharger TC. As shown in FIG. 1, the turbocharger TC includes a turbocharger body 1. The turbocharger body 1 includes a bearing housing 3, a turbine housing 5, and a compressor housing 7. The turbine housing 5 is connected to the left side of the bearing housing 3 by a fastening bolt 9. The compressor housing 7 is connected to the right side of the bearing housing 3 by a fastening bolt 11. The turbocharger TC includes a turbine T and a centrifugal compressor C. The turbine T includes a bearing housing 3 and a turbine housing 5. The turbine T is a double scroll type turbine. The centrifugal compressor C includes a bearing housing 3 and a compressor housing 7.

A bearing hole 3a is formed in the bearing housing 3. The bearing hole 3a penetrates the turbocharger TC in the left-right direction. A semi-floating bearing 13 is disposed in the bearing hole 3a. The semi-floating bearing 13 rotatably supports the shaft 15. A turbine wheel 17 is provided at the left end of the shaft 15. The turbine wheel 17 is rotatably housed in the turbine housing 5. A compressor wheel 19 is provided at the right end of the shaft 15. The compressor wheel 19 is rotatably housed in the compressor housing 7. The axial direction of the shaft 15 is the axial direction of the turbocharger TC (i.e., the left-right direction). Hereinafter, the axial, radial, and circumferential directions of the turbocharger TC (i.e., the axial, radial, and circumferential directions of the turbine wheel 17) are simply referred to as the axial, radial, and circumferential directions, respectively.

The compressor housing 7 is formed with an intake port 21. The intake port 21 opens to the right side of the turbocharger TC. The intake port 21 is connected to an air cleaner (not shown). A diffuser passage 23 is formed by the opposing surfaces of the bearing housing 3 and the compressor housing 7. The diffuser passage 23 pressurizes the air. The diffuser passage 23 is formed in an annular shape. The diffuser passage 23 is connected to the intake port 21 on the radially inner side via the compressor impeller 19.

The compressor housing 7 is also formed with a compressor scroll passage 25. The compressor scroll passage 25 is formed in an annular shape. The compressor scroll passage 25 is located, for example, radially outward of the diffuser passage 23. The compressor scroll passage 25 is connected to an intake port of the engine (not shown) and the diffuser passage 23. When the compressor impeller 19 rotates, air is drawn into the compressor housing 7 from the intake port 21. The drawn air is pressurized and accelerated as it flows between the blades of the compressor impeller 19. The pressurized and accelerated air is pressurized in the diffuser passage 23 and the compressor scroll passage 25. The pressurized air is led to the intake port of the engine.

The turbine housing 5 is formed with an exhaust flow passage 27, a housing section 29, and an exhaust flow passage 31. The exhaust flow passage 27 opens to the left side of the turbocharger TC. The exhaust flow passage 27 is connected to an exhaust gas purification device (not shown). The exhaust flow passage 27 communicates with the housing section 29. The exhaust flow passage 27 is continuous with the housing section 29 in the axial direction. The housing section 29 accommodates the turbine impeller 17. An exhaust flow passage 31 is formed on the radial outside of the housing section 29. The exhaust flow passage 31 communicates with an exhaust manifold of an engine (not shown). Exhaust gas discharged from the exhaust manifold of an engine (not shown) is guided to the exhaust flow passage 27 via the exhaust flow passage 31 and the housing section 29. The exhaust gas guided to the exhaust flow passage 27 rotates the turbine impeller 17 during the flow process.

The rotational force of the turbine wheel 17 is transmitted to the compressor impeller 19 via the shaft 15. When the compressor impeller 19 rotates, the air is pressurized as described above. In this way, the air is guided to the intake port of the engine.

Figure 2 is a cross-sectional view taken along line A-A in Figure 1. In Figure 2, only the outer periphery of the turbine impeller 17 is shown as a circle. As shown in Figure 2, the exhaust flow path 31 includes an exhaust inlet 33, an exhaust inlet passage 35, a turbine scroll flow path 37, and a scroll outlet 39.

The exhaust inlet 33 opens to the outside of the turbine housing 5. Exhaust gas discharged from the exhaust manifold of the engine (not shown) is introduced into the exhaust inlet 33.

The exhaust introduction passage 35 connects the exhaust introduction port 33 and the turbine scroll passage 37. The exhaust introduction passage 35 is formed, for example, in a straight line. The exhaust introduction passage 35 guides the exhaust gas introduced from the exhaust introduction port 33 to the turbine scroll passage 37.

The turbine scroll passage 37 communicates with the storage section 29 via the scroll outlet 39. The turbine scroll passage 37 guides the exhaust gas introduced from the exhaust introduction passage 35 to the storage section 29 via the scroll outlet 39.

A partition plate 41 is formed in the turbine housing 5. The partition plate 41 is disposed in the exhaust flow path 31 (specifically, in the exhaust inlet 33, the exhaust introduction passage 35, and the turbine scroll flow path 37). The partition plate 41 divides the exhaust flow path 31 in the circumferential direction of the turbine impeller 17. The partition plate 41 is connected in the axial direction to the inner surfaces of the exhaust inlet 33, the exhaust introduction passage 35, and the turbine scroll flow path 37. The partition plate 41 extends along the exhaust flow path 31. That is, the partition plate 41 extends along the flow direction of the exhaust gas. Hereinafter, the upstream side of the exhaust gas flow direction will be simply referred to as the upstream side, and the downstream side of the exhaust gas flow direction will be simply referred to as the downstream side.

The exhaust inlet 33 is divided into a first exhaust inlet 33a and a second exhaust inlet 33b by a partition plate 41. In this embodiment, the first exhaust inlet 33a is located radially inward from the second exhaust inlet 33b.

The exhaust introduction passage 35 is divided into a first exhaust introduction passage 35a and a second exhaust introduction passage 35b by a partition plate 41. In this embodiment, the first exhaust introduction passage 35a is located radially inward of the second exhaust introduction passage 35b. The first exhaust introduction passage 35a communicates with the first exhaust introduction port 33a. The second exhaust introduction passage 35b communicates with the second exhaust introduction port 33b.

The turbine scroll passage 37 is divided into a first turbine scroll passage 37a and a second turbine scroll passage 37b by a partition plate 41. In this embodiment, the first turbine scroll passage 37a is located radially inward from the second turbine scroll passage 37b. The first turbine scroll passage 37a communicates with the first exhaust introduction passage 35a. The second turbine scroll passage 37b communicates with the second exhaust introduction passage 35b. The first turbine scroll passage 37a and the second turbine scroll passage 37b are wound radially outwardly with respect to the turbine wheel 17. The first turbine scroll passage 37a and the second turbine scroll passage 37b are wound so as to approach the turbine wheel 17 as they proceed in the rotation direction RD of the turbine wheel 17. The radial width of each turbine scroll passage 37 becomes smaller from the upstream side to the downstream side.

The first turbine scroll passage 37a and the second turbine scroll passage 37b are each connected to the accommodation section 29 at different positions in the circumferential direction of the turbine impeller 17. The first turbine scroll passage 37a is connected to the accommodation section 29 via the first scroll outlet 39a. The second turbine scroll passage 37b is connected to the accommodation section 29 via the second scroll outlet 39b.

The first scroll outlet 39a and the second scroll outlet 39b are formed along the circumferential direction. Specifically, the first scroll outlet 39a is connected to the storage section 29 over a half circumference on one side of the storage section 29 (specifically, the half circumference on the left side in FIG. 2). The second scroll outlet 39b is connected to the storage section 29 over a half circumference on the other side of the storage section 29 (specifically, the half circumference on the right side in FIG. 2). The first scroll outlet 39a and the second scroll outlet 39b are opposed to each other in the radial direction with the turbine impeller 17 in between.

The turbine housing 5 is formed with a first tongue portion 43a and a second tongue portion 43b. In the following, when the first tongue portion 43a and the second tongue portion 43b are not particularly distinguished from each other, they are also simply referred to as tongue portions 43. Each tongue portion 43 separates the first turbine scroll passage 37a and the second turbine scroll passage 37b. Each tongue portion 43 also separates the first scroll outlet 39a and the second scroll outlet 39b.

The first tongue portion 43a is provided at a position facing the downstream end of the first turbine scroll passage 37a. The first tongue portion 43a is formed at the downstream end of the partition plate 41. The first tongue portion 43a separates the first turbine scroll passage 37a and the second turbine scroll passage 37b. The first tongue portion 43a also separates the downstream end of the first scroll outlet 39a and the upstream end of the second scroll outlet 39b.

The second tongue portion 43b is provided at a position facing the downstream end of the second turbine scroll passage 37b. The second tongue portion 43b separates the second turbine scroll passage 37b from the first turbine scroll passage 37a. The second tongue portion 43b also separates the downstream end of the second scroll outlet 39b from the upstream end of the first scroll outlet 39a.

The first tongue portion 43a and the second tongue portion 43b are arranged at equal intervals in the circumferential direction of the turbine wheel 17. In other words, the circumferential position of the first tongue portion 43a is shifted by 180° from the circumferential position of the second tongue portion 43b. However, the first tongue portion 43a and the second tongue portion 43b may be arranged at unequal intervals in the circumferential direction of the turbine wheel 17. In other words, the circumferential position of the first tongue portion 43a may be shifted by an angle other than 180° from the circumferential position of the second tongue portion 43b.

The exhaust manifold of the engine (not shown) has two or more divided paths. Some of the divided paths are connected to the first exhaust inlet 33a. Other divided paths are connected to the second exhaust inlet 33b. Exhaust gas discharged from the engine (not shown) flows through the divided paths and is introduced into the first exhaust inlet 33a or the second exhaust inlet 33b. When exhaust gas is introduced into one exhaust inlet 33, basically, exhaust gas is not introduced into the other exhaust inlet 33. The introduction of exhaust gas into the first exhaust inlet 33a and the introduction of exhaust gas into the second exhaust inlet 33b are alternately repeated.

The exhaust gas introduced into the first exhaust inlet 33a passes through the first exhaust inlet passage 35a and the first turbine scroll passage 37a, and flows from the first scroll outlet 39a to the accommodation section 29. The exhaust gas introduced into the second exhaust inlet 33b passes through the second exhaust inlet passage 35b and the second turbine scroll passage 37b, and flows from the second scroll outlet 39b to the accommodation section 29. When exhaust gas flows into one turbine scroll passage 37, basically, exhaust gas does not flow into the other turbine scroll passage 37. Therefore, a pressure difference occurs between the first turbine scroll passage 37a and the second turbine scroll passage 37b, and a leakage flow of exhaust gas occurs between the two turbine scroll passages 37. In the above leakage flow, exhaust gas leaks from one turbine scroll passage 37 to the other turbine scroll passage 37 through the vicinity of the tongue portion 43. The leakage flow of exhaust gas is a factor that reduces the performance of the turbine T and the performance of the engine connected to the turbocharger TC.

Here, the greater the distance between the tongue portion 43 and the turbine wheel 17 (specifically, the distance between the tongue portion 43 and the leading edge E1 of the blade body 17b described later when the blade body 17b of the turbine wheel 17 described later is closest to the tongue portion 43), the more likely the leakage flow of the exhaust gas will occur. Therefore, by reducing the distance between the tongue portion 43 and the turbine wheel 17, the leakage flow of the exhaust gas is suppressed. However, the smaller the distance between the tongue portion 43 and the turbine wheel 17, the greater the excitation force acting on the turbine wheel 17, and the more likely the blade vibration will increase. In the turbine T of this embodiment, by devising the shape of the part of the tongue portion 43 facing the turbine wheel 17, it is possible to reduce the blade vibration of the turbine wheel 17 and suppress the leakage flow of the exhaust gas at the same time.

Figure 3 is a cross-sectional view taken along line B-B in Figure 2 (specifically, a cross-sectional view taken along a line passing through the first tongue portion 43a and including the rotation axis of the turbine wheel 17). Figure 3 shows the shape of the portion of the first tongue portion 43a facing the turbine wheel 17. Note that the shape of the portion of the second tongue portion 43b facing the turbine wheel 17 is similar to the shape of the portion of the first tongue portion 43a facing the turbine wheel 17, and is therefore not shown.

The turbine impeller 17 has a hub 17a and multiple vanes 17b. The hub 17a is connected to the left end of the shaft 15. The outer diameter of the hub 17a decreases toward the left side of the turbocharger TC. Multiple vanes 17b are provided on the outer peripheral surface of the hub 17a. The multiple vanes 17b are provided at intervals in the circumferential direction. Each vane 17b is formed by extending radially outward from the outer peripheral surface of the hub 17a. The outer peripheral edge of the vane 17b includes a leading edge E1, a trailing edge E2, and an intermediate edge E3.

The leading edge E1 is the edge of the blade 17b on the upstream side in the flow direction of the exhaust gas. The leading edge E1 is the edge of the blade 17b on the exhaust flow path 31 side. Exhaust gas from the exhaust flow path 31 flows into the leading edge E1. The leading edge E1 is formed on the right end side of the blade 17b. The leading edge E1 extends parallel to the rotation axis of the turbine impeller 17.

The trailing edge E2 is the edge of the wing body 17b on the downstream side in the flow direction of the exhaust gas. The trailing edge E2 is the edge of the wing body 17b on the exhaust flow passage 27 side. The exhaust gas flows out from the trailing edge E2 toward the exhaust flow passage 27. The trailing edge E2 is formed on the left end side of the wing body 17b. The trailing edge E2 extends radially while twisting circumferentially.

The intermediate edge E3 is formed between the leading edge E1 and the trailing edge E2. The intermediate edge E3 extends along the shroud portion 29a that defines the accommodation portion 29 of the turbine housing 5.

The tongue portion 43 is disposed radially outward of the leading edge E1 of the blade body 17b of the turbine wheel 17. In FIG. 3, the shape of the central portion P1 in the direction of the rotation axis of the turbine wheel 17 and both ends P2, P3 in the direction of the rotation axis of the turbine wheel 17 are shown among the portions of the tongue portion 43 that face the turbine wheel 17 (specifically, the portions that face the leading edge E1). In the following, the direction of the rotation axis of the turbine wheel 17 is also simply referred to as the rotation axis direction.

End P2 is the end (i.e., the left end) of the tongue portion 43 facing the turbine wheel 17 on the discharge flow passage 27 side. The axial position of end P2 coincides with the axial position of the left end of the leading edge E1. End P3 is the end (i.e., the right end) of the tongue portion 43 facing the turbine wheel 17 on the opposite side to the discharge flow passage 27 side. The axial position of end P3 coincides with the axial position of the right end of the leading edge E1. Center portion P1 is the portion of the tongue portion 43 facing the turbine wheel 17 between end P2 and end P3. The axial position of center portion P1 coincides with the axial position of the center of the leading edge E1.

In the portion of the tongue portion 43 facing the turbine wheel 17, both ends P2 and P3 in the rotation axis direction are recessed radially outward of the turbine wheel 17 with respect to the center portion P1 in the rotation axis direction. The center portion P1 extends parallel to the rotation axis of the turbine wheel 17. When the blade body 17b is closest to the tongue portion 43, the distance (gap) between both ends P2 and P3 and the leading edge E1 is greater than the distance (gap) between the center portion P1 and the leading edge E1. In other words, the tongue portion 43 is closest to the turbine wheel 17 at the center portion P1. In the example of FIG. 3, the connection portions between each end portion P2, P3 and the center portion P1 are curved. However, the connection portions between each end portion P2, P3 and the center portion P1 may be bent.

Here, in the flow of exhaust gas in the turbine scroll passage 37, a boundary layer is formed near the wall surface, and the flow velocity becomes small. The scroll outlet 39 is formed on the inner circumferential side of the portion of the turbine scroll passage 37 connected to the accommodation section 29, so there is no wall surface. Therefore, in the portion of the turbine scroll passage 37 connected to the accommodation section 29, the circumferential component of the flow velocity of the exhaust gas is larger at the center side in the rotational axis direction than at the end side in the rotational axis direction. Therefore, if the distance between the tongue portion 43 and the turbine impeller 17 is constant regardless of the position in the rotational axis direction, exhaust gas leakage is likely to occur near the center P1 of the tongue portion 43.

As described above, in this embodiment, both ends P2, P3 of the tongue portion 43 are recessed radially outward of the turbine wheel 17 relative to the center P1 of the tongue portion 43. As a result, the center P1 of the tongue portion 43 is closer to the turbine wheel 17 than other portions. Therefore, the tongue portion 43 can be brought as close as possible to the turbine wheel 17 at the center side in the rotation axis direction where the circumferential component of the flow velocity of the exhaust gas in the turbine scroll passage 37 becomes large, while the tongue portion 43 can be separated from the turbine wheel 17 at the end side in the rotation axis direction where the circumferential component of the flow velocity of the exhaust gas in the turbine scroll passage 37 becomes small. Therefore, for example, compared to the case where the entire tongue portion 43 is brought uniformly close to the turbine wheel 17 regardless of the position in the rotation axis direction, both the reduction of the blade vibration of the turbine wheel 17 and the suppression of the leakage flow of the exhaust gas are achieved.

Here, the longer the length L1 in the rotational axis direction of the center part P1 of the tongue part 43, the greater the effect of suppressing the leakage flow of the exhaust gas. On the other hand, the longer the sum of the length L2 in the rotational axis direction of the end part P2 of the tongue part 43 and the length L3 in the rotational axis direction of the end part P3 of the tongue part 43, the greater the effect of reducing the blade vibration of the turbine impeller 17. Therefore, when the length L1 is longer than the sum of the lengths L2 and L3, the leakage flow of the exhaust gas is effectively suppressed. On the other hand, when the sum of the lengths L2 and L3 is longer than the length L1, the blade vibration of the turbine impeller 17 is effectively suppressed. However, the length L1 and the sum of the lengths L2 and L3 may be approximately the same.

In the example of FIG. 3, the length L2 of end P2 in the rotational axis direction and the length L3 of end P3 in the rotational axis direction are approximately the same, but the relationship between length L2 and length L3 is not limited to this example.

For example, length L2 may be longer than length L3. In this case, the area where the distance between the leading edge E1 and the tongue portion 43 is large on the shroud side (shroud portion 29a side) of the leading edge E1 becomes wider, so the excitation force acting on the shroud side portion of the leading edge E1 becomes smaller. Therefore, the vibration response can be suppressed for vibration modes in which the vibration displacement is large in this portion.

For example, length L3 may be longer than length L2. Here, a separation vortex may occur near the hub side (i.e., the side opposite the shroud side) of the leading edge E1, and this separation vortex may fluctuate the flow field near the shroud side of the leading edge E1 and become an excitation source for a vibration mode in which the vibration displacement becomes large in this part. When length L3 is longer than length L2, the area where the distance between the leading edge E1 and the tongue portion 43 is large becomes wider on the hub side of the leading edge E1, so the fluctuation of the flow field in the hub side part of the leading edge E1 becomes smaller, and the fluctuation of the separation vortex also becomes smaller. Therefore, it may be possible to suppress the vibration response to a vibration mode in which the vibration displacement becomes large in the shroud side part of the leading edge E1.

In the above, an example in which both ends P2 and P3 of the tongue portion 43 are recessed radially outward from the central portion P1 has been described, but it is sufficient that at least one of the ends P2 and P3 is recessed radially outward from the central portion P1. For example, only the left end P2 of the ends P2 and P3 may be recessed radially outward from the central portion P1. For example, only the right end P3 of the ends P2 and P3 may be recessed radially outward from the central portion P1. In these cases, the same effect as above is achieved. However, from the viewpoint of effectively achieving both reduction of blade vibration of the turbine impeller 17 and suppression of exhaust gas leakage flow, it is preferable that both ends P2 and P3 are recessed radially outward from the central portion P1.

In the above, all parts of the central portion P1 are located radially inward relative to both ends P2 and P3. However, a part of the central portion P1 may be located radially outward relative to the end P2 or end P3.

Although an example in which the turbine wheel 17 is of the radial type (i.e., a type in which the leading edge E1 extends parallel to the rotation axis of the turbine wheel 17) has been described above, the shape of the leading edge E1 is not limited to the above example. For example, the turbine wheel 17 may be of the mixed-flow type (i.e., a type in which the leading edge E1 is inclined radially outward as it approaches the discharge flow passage 27). In addition, when the turbine wheel 17 is of the mixed-flow type, the central portion P1 of the tongue portion 43 may extend along the leading edge E1. In other words, the central portion P1 may be inclined radially outward as it approaches the discharge flow passage 27.

In the above, an example has been described in which the shape of the portion facing the turbine wheel 17 is common between the first tongue portion 43a and the second tongue portion 43b, but the shape of the portion facing the turbine wheel 17 may be different between the first tongue portion 43a and the second tongue portion 43b. For example, in either the first tongue portion 43a or the second tongue portion 43b, neither end portion P2, P3 may be recessed radially outward from the central portion P1.

Although an example in which the turbine T is of a double scroll type has been described above, the type of the turbine T is not limited to the above example. For example, the number of turbine scroll passages 37 provided in the turbine T may be one. In this case, the number of tongue portions 43 provided in the turbine T is one. For example, the turbine T may be of a twin scroll type having two turbine scroll passages 37 arranged side by side in the axial direction. However, when the turbine T is of a double scroll type, it is particularly important to suppress the leakage flow of exhaust gas. Therefore, it is particularly effective to devise the shape of the part of the tongue portion 43 facing the turbine impeller 17 as described above.

Although the embodiments of the present disclosure have been described above with reference to the attached drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure.

In the above, an example in which the turbine T is mounted on a turbocharger TC has been described, but the turbine T may also be mounted on a device other than a turbocharger TC (e.g., a generator, etc.).

In the above, an example was described in which the first exhaust inlet 33a, the first exhaust inlet passage 35a, and the first turbine scroll passage 37a, and the second exhaust inlet 33b, the second exhaust inlet passage 35b, and the second turbine scroll passage 37b are arranged radially side by side, but the positional relationship between the components in the exhaust passage 31 is not limited to this example. For example, the first exhaust inlet 33a, the first exhaust inlet passage 35a, and the first turbine scroll passage 37a, and the second exhaust inlet 33b, the second exhaust inlet passage 35b, and the second turbine scroll passage 37b may be arranged partially in the axial direction.

This disclosure can be used in turbines and turbochargers.

17 Turbine impeller 29 Housing portion 37 Turbine scroll passage 37a First turbine scroll passage 37b Second turbine scroll passage 43 Tongue portion 43a First tongue portion 43b Second tongue portion P1 Center portion P2 End portion P3 End portion R Arrow T Turbine TC Supercharger

Claims (3)

a housing portion that houses a turbine wheel;
a turbine scroll flow passage wound radially outwardly around the turbine wheel and communicating with the housing;
a tongue portion provided at a position facing a downstream end of the turbine scroll passage, partitioning the turbine scroll passage, and having at least one end portion in a rotational axis direction of the turbine wheel, the end portion being recessed radially outward from the turbine wheel with respect to a center portion in the rotational axis direction, in a portion facing the turbine wheel;
Equipped with
a central portion in the rotation axis direction of the tongue portion facing the turbine wheel is closer to the turbine wheel than the at least one end portion of the tongue portion;
Turbine. In a portion of the tongue portion facing the turbine wheel, both end portions in the rotation axis direction are recessed radially outward from the turbine wheel with respect to a central portion in the rotation axis direction , and the central portion in the rotation axis direction is closer to the turbine wheel than other portions.
The turbine of claim 1 . A turbocharger equipped with the turbine according to claim 1 or 2.

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