JP2011231715A - Radial turbine, and supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve efficiency in working at a large flow rate without making the size of a device larger.SOLUTION: A radial turbine includes: a turbine shroud 22 having a bypass opening 10a facing an area where a turbine blade 21b rotates and located at a throat area R of a radial impeller or at an upper stream side than the throat region R; and a bypass flow passage 10 communicated up to the downstream side of the turbine impeller 21 with the bypass opening 10a serving as the inlet opening thereof.

Description

  The present invention relates to a radial turbine and a supercharger.

As is well known, a radial turbine obtains rotational power by receiving a fluid supplied from the outside with a radial impeller, and is used, for example, in a supercharger.
In such a radial turbine, even when a large amount of fluid is supplied from the outside, the capacity is increased so as not to hinder the flow of the fluid (for example, Patent Document 1).

As a method for increasing the capacity of the radial turbine, for example, a method using a waste gate valve or a method using a vane nozzle mechanism is used.
For example, in the method using the wastegate valve, the upstream side and the downstream side of the radial impeller are connected by a bypass passage provided with the wastegate valve, and when a large amount of fluid is supplied, the wastegate valve is opened to Bypass some of the.
In the method using the vane nozzle mechanism, the radial impeller is formed in a size that can handle a large flow rate in advance, and the efficiency reduction at the time of the small flow rate is improved using the vane nozzle mechanism.

Japanese Patent No. 3355801

However, when the wastegate valve is used, the fluid flowing through the bypass flow channel flows to the downstream side of the radial impeller without performing work on the radial impeller. For this reason, the greater the flow rate of the supplied fluid, the lower the efficiency.
On the other hand, in the method using the vane nozzle mechanism, the radial impeller itself is increased in size, and further, since it is necessary to mount a complicated vane nozzle mechanism, the apparatus size of the radial turbine is increased.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to improve work efficiency at a large flow rate in a radial turbine without increasing the apparatus size.

  The present invention adopts the following configuration as means for solving the above-described problems.

  1st invention is a radial turbine provided with the radial impeller which has a some turbine blade, Comprising: The bypass located in the throat area | region of the said radial impeller or an upstream from this throat area | region facing the area | region where the said turbine blade rotates A configuration in which a turbine shroud having an opening for opening and a bypass passage communicating with the bypass opening as an inlet opening to the downstream side of the radial impeller is employed.

  According to a second invention, in the first invention, the bypass flow path is connected to the bypass opening and penetrates the turbine shroud, and is connected to the through hole area and the turbine shroud. A configuration is adopted in which a gap region is formed by a gap between the housing surrounding the turbine shroud.

  A third invention adopts a configuration in which, in the second invention, the through hole region is formed to extend from the bypass opening toward the wake side in the axial direction of the radial turbine. .

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the opening area of the outlet opening of the bypass flow path is set wider than the opening area of the inlet opening of the bypass flow path To do.

  According to a fifth invention, in any one of the first to fourth inventions, a configuration is adopted in which the bypass opening is provided facing the throat region.

  6th invention is a supercharger provided with a radial turbine and a compressor, Comprising: The structure of providing the radial turbine which is any one of the said 1st-5th invention as said radial turbine is employ | adopted.

According to the present invention, the inlet opening of the bypass passage is formed facing the region where the turbine blade rotates. For this reason, the fluid flowing into the bypass flow channel flows into the bypass flow channel after passing through at least a region where the turbine blade of the radial impeller rotates. Therefore, according to the present invention, power can be obtained from the bypassed fluid, and the turbine efficiency is improved.
In the present invention, the inlet opening is provided upstream of the throat region or the throat region. For this reason, even when the supplied fluid has a large flow rate, it is not necessary to pass a part of the fluid through the throat region, which is the region where the fluid is most difficult to pass, and the fluid can be smoothly passed through the bypass flow path. For this reason, this invention becomes a large capacity radial turbine, without enlarging a radial impeller.
Therefore, according to the present invention, it is possible to improve work efficiency at a large flow rate without increasing the size of the apparatus.

It is sectional drawing which shows schematic structure of the supercharger in one Embodiment of this invention. It is an expanded sectional view containing the turbine shroud with which the supercharger in one embodiment of the present invention is provided. It is the arrow view seen from the A direction of FIG. It is the arrow view seen from the B direction of FIG. 4 is a graph in which the horizontal axis represents the position in the flow direction including the inlet and outlet of the turbine impeller, and the vertical axis represents the wall surface static pressure of the turbine shroud. It is the graph which compared the flow volume and efficiency in the supercharger in one Embodiment of this invention, and calling it a conventional supercharger. It is the schematic which shows the modification of the opening for bypasses with which the supercharger in one Embodiment of this invention is provided.

  Hereinafter, an embodiment of a radial turbine and a supercharger according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

FIG. 1 is a cross-sectional view showing a schematic configuration of a supercharger 1 according to the present embodiment.
As shown in this figure, the supercharger 1 of this embodiment compresses air with a radial turbine 2 that collects the kinetic energy of exhaust gas (fluid) as rotational power, and the rotational power obtained by the radial turbine 2. And a shaft portion 4 that connects the radial turbine 2 and the compressor 3 to transmit power from the radial turbine 2 to the compressor 3.

  The radial turbine 2 includes a turbine impeller 21 (radial impeller), a turbine shroud 22 (turbine shroud), and a turbine housing 23 (housing).

The turbine impeller 21 is rotationally driven by receiving exhaust gas supplied from a combustion engine such as an engine, and is a so-called radial impeller.
The turbine impeller 21 is configured by attaching a plurality of turbine blades 21b to the disk 21a in a rotational direction.

As shown in the enlarged view of FIG. 2, each turbine blade 21b is provided along the concavely curved surface of the disk 21a, and is curved along the flow direction of the exhaust gas.
In addition, the name of each part of the turbine blade 21b will be described. An end portion fixed to the disk 21a is referred to as a hub 21b1, an end portion facing the hub 21b1 is referred to as a tip 21b2, and an end portion on the side into which exhaust gas flows. Is referred to as a front edge 21b3, and an end on the side from which exhaust gas is discharged is referred to as a rear edge 21b4. Further, a region where the exhaust gas is most difficult to pass in a region where adjacent turbine blades 21b are close to each other is referred to as a throat region R.

As shown in FIG. 1, the turbine shroud 22 is a case that covers the turbine impeller 21 from the tip 21 b 2 side of the turbine blade provided in the turbine impeller 21.
And the turbine shroud 22 of this embodiment is provided with the opening 10a for bypasses which faces the upstream of the above-mentioned throat area | region R, as shown in FIG.
FIG. 3 is an arrow view seen from the direction A of FIG. As shown in this figure, a plurality of bypass openings 10 a are provided on the inner wall surface of the turbine shroud 22, and are arranged annularly around the rotation axis of the turbine impeller 21. Each bypass opening 10a is circularly set.

  Further, the turbine shroud 22 is formed with a plurality of through holes 10 b that are connected to the bypass openings 10 a and penetrate the turbine shroud 22. These through-holes 10b constitute a part of the bypass passage 10 which will be described in detail later.

The turbine housing 23 forms the outer shape of the radial turbine 2 and surrounds the turbine impeller 21 together with the turbine shroud 22.
A scroll passage 24 having an exhaust gas inlet at one end is formed inside the turbine housing 23.
A ring member 25 having a larger diameter than the turbine impeller 21 is disposed inside the turbine housing 23 so as to face the turbine shroud 22. A region sandwiched between the ring member 25 and the turbine shroud 22 is an annular exhaust gas passage 26 that communicates the scroll passage 24 with the turbine impeller 21.
In the present embodiment, a variable nozzle mechanism is provided. This variable nozzle mechanism includes a plurality of nozzle vanes 27 arranged in an annular shape in the exhaust gas passage 26. These nozzle vanes 27 are arranged in an annular shape and can be rotated by a driving mechanism (not shown), and the rotation angle is optimally set according to the flow rate of exhaust gas flowing through the exhaust gas passage 26.

As shown in FIG. 2, a gap 10 c is provided in a part between the turbine shroud 22 and the turbine housing 23. This gap 10 c constitutes a part of the bypass flow path 10, communicates with the through hole 10 b and communicates with the downstream side of the radial turbine 2.
FIG. 4 is an arrow view seen from the direction B of FIG. As shown in this figure, the gap 10c is continuously provided over the entire circumference around the rotation axis of the turbine impeller 21.

  The bypass flow path 10 is a flow path for bypassing a part of the exhaust gas that passes through the turbine impeller 21, and is formed by the above-described through hole 10b and the gap 10c. That is, in the supercharger 1 of the present embodiment, the bypass flow path 10 is connected to the bypass opening 10a formed in the turbine shroud 22 and penetrates the turbine shroud 22, and the through hole area Ra. It has a gap region Rb formed by a gap 10c between the turbine shroud 22 and the turbine housing 23 surrounding the turbine shroud 22 while being connected.

Further, in the supercharger 1 of the present embodiment, the bypass opening 10a serving as the inlet opening of the bypass channel 10 faces the upstream side of the throat region R, which is the region where the exhaust gas hardly passes as described above. Is provided.
FIG. 5 is a graph in which the horizontal axis represents the position in the flow direction including the inlet and outlet of the turbine impeller 21 and the vertical axis represents the wall surface static pressure of the turbine shroud 22. As shown in this figure, when the flow rate of the exhaust gas supplied to the radial turbine 2 is a small flow rate (a flow rate having a sufficient margin with respect to the capacity of the turbine impeller 21), the turbine impeller 21 is introduced from the inlet. The wall surface static pressure of the turbine shroud 22 hardly changes up to the downstream side.
Further, as the flow rate of the exhaust gas supplied to the radial turbine 2 increases, the wall surface static pressure of the turbine shroud 22 increases from the inlet to the throat region, and the wall surface static pressure of the turbine shroud 22 on the downstream side of the turbine impeller 21 increases. descend.
For this reason, by providing the opening 10a for bypass in the throat area | region R or its upstream as mentioned above, an exhaust gas does not flow into the bypass flow path 10 in the case of a small flow rate, without providing a special drive mechanism etc. The exhaust gas can flow into the bypass channel 10 as the flow rate increases.

In addition, the exhaust gas flowing through the bypass channel 10 expands toward the downstream as the pressure decreases. For this reason, in order to ensure a smooth flow of the exhaust gas in the bypass channel 10, at least the outlet opening 10d of the bypass opening 10a (the outlet of the gap 10c shown in FIG. 4) is larger than the total opening area of the bypass opening 10a. The area of the opening) is preferably large.
Furthermore, in order to ensure a smoother exhaust gas flow, it is preferable to adopt a configuration in which the bypass channel 10 gradually increases the channel area toward the downstream. For example, the opening area in the region where the through hole 10b and the gap 10c are connected is expanded in a range up to 1.5 times the opening area of the bypass opening 10a, and the opening area of the outlet opening 10d is increased between the through hole 10b and the gap 10c. By adopting a configuration that further expands the opening area in the region where the two are connected, the exhaust gas can flow smoothly in the bypass channel 10.

  In the supercharger 1 of the present embodiment, the through hole region Ra (that is, the through hole 10b) of the bypass channel 10 extends from the bypass opening 10a toward the wake side in the axial direction of the radial turbine 2. Is formed. As a result, the through-hole region Ra extends along the flow direction of the exhaust gas inside the turbine shroud 22, and the exhaust gas can smoothly flow into the bypass flow path 10. Note that, for example, the through hole region Ra has an extending direction set to an angle range of 0 to 45 ° with respect to a plane orthogonal to the rotation axis of the turbine impeller 21, so that the radial turbine 2 is connected to the bypass opening 10 a. Direct toward the wake side in the axial direction.

  In the supercharger 1 of this embodiment having such a configuration, exhaust gas is supplied to the radial turbine 2 and the turbine impeller 21 is rotationally driven, whereby the kinetic energy of the exhaust gas is recovered as rotational power. Then, the rotational power collected by the radial impeller 2 is transmitted to the compressor 3 through the shaft portion 4 to compress the air.

In the supercharger 1 of the present embodiment, a bypass opening 10 a that is an inlet opening of the bypass flow path 10 is formed in the turbine shroud 22 that surrounds the turbine impeller 21. For this reason, the exhaust gas flowing into the bypass flow path 10 flows into the bypass flow path 10 after passing through at least the region where the turbine blades 21b of the turbine impeller 21 rotate. Therefore, according to the supercharger 1 of the present embodiment, power can be obtained from the exhaust gas that is bypassed, and the turbine efficiency is improved.
In the supercharger 1 of the present embodiment, the inlet opening (bypass opening 10a) is provided on the upstream side of the throat region R. For this reason, even when the exhaust gas to be supplied has a large flow rate, it is not necessary to pass a part of the exhaust gas through the throat region R, which is the region where the exhaust gas is most difficult to pass, and the exhaust gas can be smoothly passed through the bypass channel 10. it can. For this reason, the supercharger 1 of this embodiment becomes a large capacity radial turbine without enlarging the turbine impeller 21.
Therefore, according to the supercharger 1 of this embodiment, it becomes possible to improve the work efficiency at the time of a large flow rate without increasing the apparatus size.

FIG. 6 compares the flow rate and efficiency in the supercharger 1 of the present embodiment and a supercharger (referred to as a conventional supercharger) having a configuration in which the bypass passage 10 is removed from the supercharger 1 of the present embodiment. It is a graph.
In addition, (a) has shown the relationship between the flow volume and efficiency in the case of making the size of the turbine impeller of the supercharger 1 of this embodiment and the conventional supercharger correspond. As can be seen from (a), the maximum flow rate is increased by providing the bypass channel 10.
Further, (b) shows the relationship between the flow rate and efficiency when the size of the turbine impeller of the conventional turbocharger is increased and the maximum flow rates of the turbocharger 1 of this embodiment and the conventional turbocharger are matched. Show. As can be seen from (b), by providing the bypass flow path 10, it is not necessary to increase the size of the turbine impeller, and the efficiency on the small flow rate side can be improved.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above embodiment, the configuration in which the bypass opening 10a is circularly set has been described.
However, the present invention is not limited to this, and a slit-shaped bypass opening 10A may be adopted instead of the circular bypass opening 10a as shown in FIG.

Moreover, in the said embodiment, the structure by which the opening 10a for bypasses was formed facing the upstream of the throat area | region R was demonstrated.
However, the present invention is not limited to this, and the bypass opening 10a may be formed facing the throat region R in a range facing the region where the turbine blade 21b rotates.

Moreover, in the said embodiment, the structure by which the radial turbine of this invention is used as a turbine of a supercharger was demonstrated.
However, the present invention is not limited to this, and can be applied to all radial turbines.

  Moreover, in the said embodiment, the structure provided with a variable nozzle mechanism was demonstrated. However, the present invention is not limited to this, and a configuration in which the variable nozzle mechanism is not installed or a configuration in which a fixed nozzle mechanism is provided instead of the variable nozzle mechanism can be adopted.

Moreover, in the said embodiment, the structure by which the bypass flow path 10 was formed of through-hole area | region Ra and clearance gap area Rb was demonstrated.
However, the present invention is not limited to this. For example, the through hole 10b can be extended to the downstream side of the turbine impeller, and the bypass flow path 10 can be formed only by the through hole 10b.

  DESCRIPTION OF SYMBOLS 1 ... Supercharger, 2 ... Radial turbine, 10 ... Bypass flow path, 10a, 10A ... Bypass opening (inlet opening), 10b ... Through-hole, 10c ... Clearance, 10d ... Outlet opening, 21 ... Turbine impeller (radial impeller), 21b ... Turbine blade, 22 ... Turbine shroud, R ... Throat region, Ra ... Through hole region, Rb ... Gap region

Claims (6)

A radial turbine comprising a radial impeller having a plurality of turbine blades,
A turbine shroud having a throat region of the radial impeller facing the region where the turbine blade rotates or a bypass opening located upstream of the throat region;
A radial turbine comprising: a bypass flow path that communicates with the bypass opening as an inlet opening to a downstream side of the radial impeller.   The bypass flow path is formed by a through hole region connected to the bypass opening and penetrating the turbine shroud, and a gap between the turbine shroud and a housing surrounding the turbine shroud and connected to the through hole region. The radial turbine according to claim 1, wherein the radial turbine has a gap area.   The radial turbine according to claim 2, wherein the through-hole region is formed to extend from the bypass opening toward a wake side in the axial direction of the radial turbine.   The radial turbine according to any one of claims 1 to 3, wherein an opening area of an outlet opening of the bypass passage is set wider than an opening area of an inlet opening of the bypass passage.   The radial turbine according to claim 1, wherein the bypass opening is provided facing the throat region. A turbocharger comprising a radial turbine and a compressor,
A turbocharger comprising the radial turbine according to claim 1 as the radial turbine.

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