JP2007192180A - Turbine for turbocharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turbine for a turbocharger, which can be easily formed while restricting deterioration of turbine efficiency. <P>SOLUTION: In the turbine 30, a housing 39 includes a turbine chamber 31 extended along a rotation axis L1 of a turbine wheel 32 to house the turbine wheel 32, scroll passages 33 and 34 spirally extended around the turbine chamber 31, nozzle passages 35 and 36 opened along the whole circumference of a circumferential wall of the turbine chamber 31 to communicate the turbine chamber 31 and the scroll passages 33 and 34 with each other, and a plurality of nozzle vanes formed inside the nozzle passages 35 and 36 to be disposed around the rotation axis L1 at a prescribed interval. The housing 39 comprises two split members 39A and 39B which are separately molded. The first split member 39A includes the whole nozzle passages 35 and 36 and the whole nozzle vanes 37 and 38. The second split member 39B includes part of the scroll passages 33 and 34. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust drive type turbocharger turbine, and more particularly to a turbocharger turbine in which nozzle vanes are provided in a nozzle passage.

  Generally, in order to improve the output of an internal combustion engine for automobiles or the like, it is preferable to increase the amount of air charged in the engine combustion chamber. Therefore, an exhaust-driven turbocharger has been proposed and put into practical use as a device for enhancing the charging efficiency by forcibly sending air.

  In such a turbocharger turbine, the turbine wheel is accommodated in a turbine chamber extending along the rotation axis of the turbine wheel. A scroll passage extending in a spiral shape is formed on the outer periphery of the turbine chamber, and the scroll passage and the turbine chamber communicate with each other through a nozzle passage. The nozzle passage has a passage cross-sectional area smaller than that of the scroll passage, and is open over the entire circumference of the peripheral wall of the turbine chamber. A plurality of turbine blades project from the surface of the turbine wheel, and a plurality of passages (inter-blade passages) partitioned by the turbine blades are formed between the peripheral wall of the turbine wheel and the turbine wheel. ing.

  In this turbocharger, the exhaust gas of the internal combustion engine is introduced into the scroll passage, and the exhaust gas is blown onto the turbine wheel while increasing the flow velocity when passing through the nozzle passage. When the exhaust flow from the nozzle passage passes through the inter-blade passage, the turbine blades are rotated by the turbine blades receiving the energy of the exhaust flow.

In addition, a turbocharger described in Patent Document 1 in which a plurality of nozzle vanes are disposed in a nozzle passage of a turbine has been proposed. The nozzle vanes are arranged at a predetermined interval around the rotation axis of the turbine wheel. In this turbocharger, the flow velocity of the exhaust flow is further increased when passing between adjacent nozzle vanes.
Japanese Utility Model Publication No. 1-130036

  The turbine of the turbocharger described above has a complicated structure in which a scroll passage, a nozzle passage, and a nozzle vane are formed inside the housing. For this reason, when the turbine housing is integrated, the operation for forming the turbine becomes complicated.

  On the other hand, for example, the housing of the turbine can be constituted by a plurality of parts such as dividing the housing of the turbine along the extending direction of the nozzle passage, or making the nozzle vane another component. With such a divided structure, each of the component parts (divided bodies) having a shape exposed to the scroll passage, the nozzle passage, and the nozzle vane is separately molded, and then the divided bodies are assembled together to form a turbine housing. It becomes possible. Therefore, it is possible to easily form a housing in which a scroll passage, a nozzle passage, and nozzle vanes are formed, as compared with a turbine having a housing with an integral structure.

  However, if such a divided structure is adopted, a step may be formed at the mating part of each divided body or a clearance may be formed between the mating surfaces of each divided body due to the effects of tolerances and assembly errors of each divided body. There is. And when such a level | step difference and clearance are formed in the flow path through which an exhaust flow passes, there exists a possibility of causing the fall of turbine efficiency resulting from this.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a turbocharger turbine that can be easily formed while suppressing a decrease in turbine efficiency.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
According to a first aspect of the present invention, there is provided a turbine chamber that extends along a rotation axis of the turbine wheel and accommodates the turbine wheel, a scroll passage that spirally extends around the outer periphery of the turbine chamber, A nozzle passage that is opened over the entire circumference of the peripheral wall and communicates with the turbine chamber and the scroll passage, and a plurality of nozzle vanes that are formed in the nozzle passage so as to be disposed at a predetermined interval around the rotation shaft. In the turbine of the turbocharger formed in the housing, the housing is composed of a plurality of divided bodies integrally formed separately, and the specific divided body among the divided bodies is the whole of the nozzle passage and the nozzle vane. The gist of the invention is that it includes the whole and the other divided body includes a part of the scroll passage.

  Since the nozzle passage in the turbine is a portion where the flow velocity of the exhaust flow becomes extremely high, if a step is formed on the inner wall surface, the turbine efficiency is significantly lowered. Further, in a turbine having a structure in which a clearance exists between the inner wall surface of the nozzle passage and the nozzle vane, a part of the exhaust flow passes through the clearance, and thus a reduction in turbine efficiency is unavoidable.

  In this regard, according to the above configuration, although the turbine housing is divided, the nozzle passage and the plurality of nozzle vanes provided in the nozzle passage are integrally formed as a specific divided body. The mating surface of each divided body can be set at a portion other than the nozzle passage. Therefore, it is possible to form a turbine in which there is no unnecessary step on the inner wall surface of the nozzle passage and there is no clearance between the nozzle passage and the nozzle vane, and the turbine efficiency resulting from the division of the turbine housing Can be suitably suppressed.

  Moreover, since a divided body including a part of the scroll passage is formed separately from the specific divided body, the shape of the specific divided body is changed to a portion corresponding to the scroll passage side in the nozzle passage or the scroll passage side in the nozzle vane. It becomes possible to make it the shape which the part which corresponds hits. Moreover, it becomes possible to make the shape of another division body into the shape which the part which corresponds to a scroll channel | path exposed. Therefore, it is possible to easily form the scroll passage, the nozzle passage, and the nozzle vane inside the housing as compared with a turbine having a single housing structure.

  According to a second aspect of the present invention, in the turbocharger turbine according to the first aspect, the housing has two nozzle passages formed therein, and the plurality of nozzle vanes are formed in the nozzle passages, respectively. The specific divided body includes the whole of the two nozzle passages and the whole of the nozzle vanes formed inside the nozzle passages.

  According to the said structure, the turbine of the very complicated internal structure provided with 2 sets of nozzle passages and the some nozzle vane corresponding to this can be formed easily, suppressing the fall of turbine efficiency.

  As a turbine having two sets of nozzle passages and a plurality of nozzle vanes corresponding to the nozzle passages, one of the two nozzle passages is opened at the inlet of the inter-blade passage in the turbine wheel, according to claim 3, It is possible to employ a turbine having a structure in which the other is opened in the middle of the passage between the blades.

  In the turbine, a plurality of passages (the inter-blade passages) partitioned by a plurality of turbine blades projecting from the surface of the turbine wheel are formed between the peripheral wall of the turbine chamber and the turbine wheel. . The inter-blade passage has an upstream end in the exhaust flow direction as an inlet, and an downstream end in the exhaust flow direction as an outlet.

Hereinafter, an embodiment of the present invention will be described.
FIG. 1 shows a schematic configuration of an internal combustion engine to which the turbocharger turbine according to the present embodiment is applied.

  As shown in FIG. 1, the turbocharger 10 includes a compressor 20 disposed in the intake passage 2 of the internal combustion engine 1, a turbine 30 disposed in the exhaust passage 3 of the internal combustion engine 1, the compressor 20 and And a center housing 40 to which the turbine 30 is connected.

FIG. 2 shows a specific configuration of the turbocharger 10.
As shown in FIG. 2, a compressor chamber 21 is formed inside the compressor 20, and a compressor impeller 22 is accommodated in the compressor chamber 21. On the other hand, a turbine chamber 31 is formed inside the turbine 30, and a turbine wheel 32 is accommodated in the turbine chamber 31. On the other hand, a shaft 41 is rotatably supported by the center housing 40, the compressor impeller 22 is fixed to one end of the shaft 41, and the turbine wheel 32 is fixed to the other end. The turbocharger 10 has a structure in which the compressor impeller 22 and the turbine wheel 32 rotate integrally.

  The compressor chamber 21 of the compressor 20 extends along the rotation axis L <b> 1 of the compressor impeller 22. The compressor 20 includes a scroll passage 23 that spirally extends around the outer periphery of the compressor impeller 22, and the scroll passage 23 is opened in an annular shape over the entire circumference of the peripheral wall of the compressor chamber 21.

  On the other hand, the turbine chamber 31 of the turbine 30 extends along the rotation axis L <b> 1 of the turbine wheel 32. The turbine 30 includes two scroll passages 33 and 34 that spirally extend around the outer periphery of the turbine wheel 32. One of the scroll passages 33 and 34 communicates with the turbine chamber 31 through the nozzle passage 35 and the other through the nozzle passage 36. Each nozzle passage 35, 36 is opened in an annular shape over the entire circumference of the peripheral wall of the turbine chamber 31.

  In the present embodiment, among the scroll passages 33, 34 and the nozzle passages 35, 36, the passage communicated upstream in the exhaust flow direction in the turbine chamber 31 is defined as the first scroll passage 33 and the first scroll passage 33. A nozzle passage 35 and a passage communicating downstream in the exhaust flow direction are referred to as a second scroll passage 34 and a second nozzle passage 36.

A plurality of nozzle vanes 37 and 38 are provided in the first nozzle passage 35 and the second nozzle passage 36, respectively.
FIG. 3 shows an arrangement mode of the nozzle vanes 37 provided in the first nozzle passage 35.

  As shown in FIG. 3, the nozzle vanes 37 are arranged around the rotation axis L <b> 1 of the turbine wheel 32 at a predetermined interval. When passing between adjacent nozzle vanes 37, the flow direction of the exhaust flow passing through the first nozzle passage 35 (FIG. 2) is adjusted and the flow velocity of the exhaust flow is increased.

  Similarly to the nozzle vane 37, the nozzle vane 38 provided in the second nozzle passage 36 is also arranged around the rotation axis L <b> 1 of the turbine wheel 32 at a predetermined interval. When passing between adjacent nozzle vanes 38, the flow direction of the exhaust flow passing through the second nozzle passage 36 is adjusted and the flow velocity of the exhaust flow is increased.

  In the turbine 30, the turbine chamber 31, the scroll passages 33 and 34, the nozzle passages 35 and 36, and the nozzle vanes 37 and 38 are all formed inside the housing 39.

FIG. 4 shows a side structure of the turbine wheel 32.
As shown in FIG. 4, a plurality of turbine blades 32 a protrude from the surface of the turbine wheel 32. In the turbine chamber 31 (FIG. 2), a plurality of passages (blade passages) partitioned by the turbine blades 32a are formed between the peripheral wall and the turbine wheel 32. Normally, the exhaust flow of the internal combustion engine 1 is passed through this inter-blade passage from the upstream end in the turbine chamber 31 in the exhaust flow direction (inlet Ei of the inter-blade passage) to the downstream end in the exhaust flow direction (inter-blade passage). Pass towards the exit Eo). The inlet Ei of the inter-blade passage is a portion corresponding to a so-called leading edge of a turbine wheel in a standard turbocharger in which only one nozzle passage is provided. The outlet Eo of the inter-blade passage is a portion corresponding to a so-called trading edge of a standard turbocharger turbine wheel.

  In the turbocharger 10 of the present embodiment, the first nozzle passage 35 is opened at the inlet Ei of the inter-blade passage, and the second nozzle passage 36 is in the middle of the inter-blade passage (inlet of the inter-blade passage). It is opened at a position between Ei and outlet Eo.

In the turbocharger 10, the internal combustion engine 1 is basically supercharged as follows.
In the turbocharger 10, when the exhaust flow of the internal combustion engine 1 passes through the inter-blade passage, the turbine blade 32a receives the energy of the exhaust flow to rotate the turbine wheel 32. The rotation of the turbine wheel 32 is transmitted to the compressor impeller 22 of the compressor 20 through the shaft 41, and the compressor impeller 22 rotates. As a result, in the compressor 20, the intake air flowing into the compressor chamber 21 from the inlet portion 20 a of the compressor 20 due to the centrifugal force caused by the rotation of the compressor impeller 22 causes the scroll passage 23, and hence the combustion chamber 4 of the internal combustion engine 1 (FIG. 1). See). In the internal combustion engine 1, the output is improved by performing supercharging using the energy of the exhaust.

  Further, a flow control valve (not shown) is provided in the second scroll passage 34 of the turbocharger 10, and the turbocharger 10 is provided with a second scroll passage 34 through operation control of the flow control valve. The cross-sectional area of the passage is adjustable.

The operation control of the flow path control valve is executed as follows.
That is, first, when the internal combustion engine 1 has a small exhaust amount, such as when the internal combustion engine 1 is operated at low speed and low load, the flow path control valve is closed. At this time, exhaust gas from the internal combustion engine 1 is blown onto the turbine wheel 32 only through the first scroll passage 33 and the first nozzle passage 35. In the turbocharger 10, the shape of the inlet of the inter-blade passage, the shape of the first scroll passage 33, the shape of the first nozzle passage 35, and the shape and arrangement of the nozzle vane 37 provided in the nozzle passage 35 are provided. As an arrangement mode, a shape and an arrangement mode suitable for an engine operating state with a small displacement are set. By setting in this way, the operating efficiency of the turbocharger 10 can be increased in a situation where the exhaust amount of the internal combustion engine 1 is small, that is, in a situation where the exhaust flow is blown to the turbine wheel 32 only from the first nozzle passage 35. it can.

  On the other hand, when the displacement of the internal combustion engine 1 is relatively large, such as during high speed operation or high load operation of the internal combustion engine 1, for example, the flow path control valve is opened and the engine is in an operation state with a large displacement. The opening degree of the flow path control valve is adjusted so that the opening degree increases as much as possible.

  In this case, the second scroll passage 34 and the second nozzle passage are arranged so as not to cause an excessive increase or an excessive decrease in the exhaust flow rate of the first scroll passage 33 and the first nozzle passage 35. While the exhaust gas flow rate of 36 is adjusted, exhaust gas is blown to the turbine wheel 32 from both the first nozzle passage 35 and the second nozzle passage 36. As a result, while maintaining an appropriate amount of exhaust flow from the first nozzle passage 35, in addition to the energy of the exhaust flow from the first nozzle passage 35, the energy of the exhaust flow from the second nozzle passage 36 is received. Thus, the turbine wheel 32 is rotationally driven.

  In the turbocharger 10, as the shape and arrangement of the second scroll passage 34, the second nozzle passage 36, and the nozzle vane 38 provided in the second nozzle passage 36, the internal combustion engine 1 The shape suitable for the exhaust gas flow rate passing through the second nozzle passage 36 is set during the high rotation and high load operation. Therefore, even when exhaust gas is blown to the turbine wheel from both the first nozzle passage 35 and the second nozzle passage 36, the operation efficiency of the turbocharger 10 can be increased.

  Now, the housing 39 of the turbine 30 according to the present embodiment is configured by two divided bodies 39A and 39B that are integrally formed separately by casting, and is formed by assembling these divided bodies 39A and 39B together. Is done.

Hereinafter, the divided bodies 39A and 39B will be specifically described.
Here, first, the first divided body 39A will be described with reference to FIG.
As shown in FIG. 5, the first divided body 39 </ b> A having a shape including each configuration described below is integrally formed.
A portion on the upstream side in the exhaust flow direction of the turbine chamber 31 (including the opening on the turbine chamber 31 side of each nozzle passage 35, 36).
A portion on the inner peripheral side (first nozzle passage 35 side) of the first scroll passage 33 and a portion on the inner peripheral side (second nozzle passage 36 side) of the second scroll passage 34.
The whole of the first nozzle passage 35 and the second nozzle passage 36 respectively.
The entire nozzle vanes 37 formed in the first nozzle passage 35 and the entire nozzle vanes 38 formed in the second nozzle passage 36;

Next, the second divided body 39B will be described with reference to FIG.
As shown in FIG. 6, the second divided body 39 </ b> B having a shape including the following components is integrally formed.
A portion of the turbine chamber 31 on the downstream side in the exhaust flow direction.
A portion on the outer peripheral side of the first scroll passage 33 and a portion on the outer peripheral side of the second scroll passage 34.

  Here, since the nozzle passages 35 and 36 are portions where the flow velocity of the exhaust flow is particularly high in the turbine 30 (FIG. 2), if steps are formed on the inner wall surfaces of the nozzle passages 35 and 36, The exhaust flow passing through the nozzle passages 35 and 36 is greatly disturbed due to the generation of vortices and turbulence, and the turbine efficiency is significantly reduced.

  Further, in the turbine having a structure in which a clearance exists between the inner wall surface of the first nozzle passage 35 and the nozzle vane 37 or between the inner wall surface of the second nozzle passage 36 and the nozzle vane 38, the clearance is reduced. Since a part of the exhaust flow passes, a decrease in turbine efficiency due to this is unavoidable.

  The turbine 30 according to the present embodiment has a housing 39 constituted by two divided bodies 39A and 39B. Therefore, due to the influence of tolerances and assembly errors of the divided bodies 39A and 39B, a step is formed at the mating portion of the divided bodies 39A and 39B, and a clearance is formed between the mating surfaces of the divided bodies 39A and 39B. There is a risk.

  However, in the turbine 30 according to the present embodiment, the nozzle passages 35 and 36 and all the nozzle vanes 37 and 38 are integrally formed as the first divided body 39A, although the housing 39 has a divided structure. Thus, the mating surfaces of the first divided bodies 39A and the second divided bodies 39B are set at portions other than the nozzle passages 35 and 36.

  For this reason, the housing 39 is not formed with unnecessary steps on the inner wall surfaces of the nozzle passages 35, 36, and is provided between the first nozzle passage 35 and the nozzle vanes 37 or the second nozzle passage 36 and the nozzle vanes 38. There can be no clearance between the two. Therefore, a decrease in turbine efficiency due to the split structure of the housing 39 of the turbine 30 can be suitably suppressed.

  In the housing 39 of the present embodiment, the above-described steps and clearances may be formed on the inner wall surfaces of the scroll passages 33 and 34. However, since the flow velocity of the exhaust flow in each of the scroll passages 33 and 34 is lower than the flow velocity of the exhaust flow in each of the nozzle passages 35 and 36, steps or clearances are formed in each of the scroll passages 33 and 34. Even so, the effect of the disturbance of the exhaust flow is very small.

  On the other hand, if the housing 39 of the turbine 30 is integrated, a portion on the outer peripheral side (the scroll passages 33 and 34 side) of the nozzle passages 35 and 36, the entire scroll passages 33 and 34, and the nozzle vanes 37 and 38. Most of the outer peripheral side (scroll passage 33, 34 side) portion is formed in a portion that cannot be seen from the outside of the housing 39. Therefore, when such a structure is adopted, the work for forming the turbine 30 becomes extremely complicated.

  In this regard, the housing 39 of the turbine 30 according to the present embodiment is configured by a first divided body 39A and a second divided body 39B. As a result, the first divided body 39A (see FIG. 5) is divided into the outer peripheral portion of each nozzle passage 35, 36, the inner peripheral portion of each scroll passage 33, 34, and the outer peripheral side of each nozzle vane 37, 38. It can be set as the shape which this part exposed. Further, the second divided body 39B (see FIG. 6) can be formed in a shape in which a portion on the outer peripheral side of the scroll passage 33 is exposed. Therefore, the scroll passages 33, 34, the nozzle passages 35, 36, and the nozzle vanes 37, 38 can be easily formed inside the housing 39 of the turbine 30 as compared with a turbine having a single housing structure.

As described above, according to the present embodiment, the effects described below can be obtained.
(1) The housing 39 is constituted by two divided bodies 39A and 39B integrally formed separately, and the first divided body 39A includes the entire nozzle passages 35 and 36 and the entire nozzle vanes 37 and 38. The second divided body 39B is formed into a shape including the outer peripheral portion of each scroll passage 33, 34. Therefore, it is possible to suitably suppress a decrease in turbine efficiency due to the split structure of the housing 39 of the turbine 30. In addition, the scroll passages 33, 34, the nozzle passages 35, 36, and the nozzle vanes 37, 38 can be easily formed inside the housing 39 of the turbine 30 as compared with a turbine having a housing with an integral structure.

  (2) The turbine 30 having an extremely complicated internal structure including two sets of nozzle passages and a plurality of nozzle vanes corresponding to the nozzle passages can be easily formed while suppressing a decrease in turbine efficiency.

The embodiment described above may be modified as follows.
In the above embodiment, the housing 39 of the turbine 30 is configured by the two divided bodies 39A and 39B. However, the housing 39 may be configured by three or more divided bodies. In short, the turbine 30 is such that a particular division includes the entire nozzle passages 35, 36 and all of the nozzle vanes 37, 38, and the other division includes a portion of each scroll passage 33, 34. The housing 39 may be divided into a plurality of divided bodies.

The present invention can also be applied to a turbine in which each nozzle passage is opened at the entrance of the inter-blade passage.
The present invention can also be applied to a turbine including only one set of nozzle passages and a plurality of nozzle vanes corresponding to the nozzle passages.

1 is a schematic diagram showing a schematic configuration of an internal combustion engine to which an embodiment of the present invention is applied. Sectional drawing which shows the cross-section of the turbocharger of the embodiment. The schematic diagram which shows the arrangement | positioning aspect of the nozzle vane provided in a 1st nozzle channel | path. The side view which shows the side structure of a turbine wheel. Sectional drawing which shows the cross-section of a 1st division body. Sectional drawing which shows the cross-section of a 2nd division body.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Intake passage, 3 ... Exhaust passage, 4 ... Combustion chamber, 10 ... Turbocharger, 20 ... Compressor, 20a ... Inlet part, 21 ... Compressor chamber, 22 ... Compressor impeller, 23 ... Scroll passage, 30 ... turbine, 31 ... turbine chamber, 32 ... turbine wheel, 32a ... turbine blade, 33 ... first scroll passage, 34 ... second scroll passage, 35 ... first nozzle passage, 36 ... second nozzle passage, 37, 38 ... Nozzle vane, 39 ... Housing, 39A ... First divided body as a specific divided body, 39B ... Second divided body as another divided body, 40 ... Center housing, 41 ... Shaft.

Claims (3)

A turbine chamber that extends along the rotation axis of the turbine wheel and accommodates the turbine wheel; a scroll passage that spirally extends around the outer periphery of the turbine chamber; And a nozzle passage communicating with the chamber and the scroll passage, and a plurality of nozzle vanes formed in the nozzle passage so as to be disposed at predetermined intervals around the rotation shaft. In the charger turbine,
The housing is formed of a plurality of divided bodies integrally formed separately, and a specific divided body of the divided bodies includes the whole of the nozzle passage and the whole of the nozzle vane, and the other divided body is the scroll. A turbocharger turbine comprising a part of a passage. The turbocharger turbine according to claim 1,
The housing has two nozzle passages and a plurality of nozzle vanes formed in the nozzle passages, and the specific divided body includes the whole of the two nozzle passages and the nozzle passages. A turbocharger turbine comprising all of the nozzle vanes formed inside. The turbocharger turbine according to claim 2,
One of the two nozzle passages is opened at an inlet of an inter-blade passage in the turbine wheel, and the other is opened in the middle of the inter-blade passage. A turbocharger turbine, wherein:

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