Patent ID: 12221890

DESCRIPTION OF EMBODIMENTS

Now, with reference to the attached drawings, an embodiment of the present disclosure is described. The dimensions, materials, and other specific numerical values represented in the embodiment are merely examples used for facilitating the understanding of the disclosure, and do not limit the present disclosure unless otherwise particularly noted. Elements having substantially the same functions and configurations herein and in the drawings are denoted by the same reference symbols to omit redundant description thereof. Further, illustration of elements with no direct relationship to the present disclosure is omitted.

FIG.1is a schematic sectional view for illustrating a turbocharger TC according to an embodiment of the present disclosure. In the following, description is given while a direction indicated by the arrow L illustrated inFIG.1corresponds to a left side of the turbocharger TC. A direction indicated by the arrow R illustrated inFIG.1corresponds to a right side of the turbocharger TC. As illustrated inFIG.1, the turbocharger TC includes a turbocharger main body1. The turbocharger main body1includes a bearing housing3, a turbine housing5, and a compressor housing7.

The turbine housing5is coupled to a left side of the bearing housing3by a fastening mechanism9. The fastening mechanism9is, for example, a G coupling. The compressor housing7is coupled to a right side of the bearing housing3by a fastening bolt11. The turbocharger TC includes a turbine T and a centrifugal compressor C. The turbine T includes the bearing housing3and the turbine housing5. The turbine T is a twin scroll type turbine. The centrifugal compressor C includes the bearing housing3and the compressor housing7.

The bearing housing3has a bearing hole3aformed therein. The bearing hole3apasses through the bearing housing3in a right-and-left direction of the turbocharger TC. Bearings13are provided in the bearing hole3a. InFIG.1, a full floating bearing is illustrated as an example of the bearing13. However, the bearing13may be other bearing such as a semi-floating bearing or a rolling bearing. The bearings13axially support a shaft15in a rotatable manner. A turbine wheel17is provided at a left end portion of the shaft15. As described above, the turbine wheel17is mounted on a left side, which is one side of the shaft15. The turbine wheel17is accommodated in the turbine housing5so as to be rotatable. A compressor impeller19is provided at a right end portion of the shaft15. The compressor impeller19is accommodated in the compressor housing7so as to be rotatable.

An axial direction, a radial direction, and a circumferential direction of the turbocharger TC are hereinafter also simply referred to as “axial direction,” “radial direction,” and “circumferential direction,” respectively. The axial direction of the turbocharger TC corresponds to an axial direction of the shaft15, an axial direction of the turbine wheel17, and an axial direction of the compressor impeller19. The radial direction of the turbocharger TC corresponds to a radial direction of the shaft15, a radial direction of the turbine wheel17, and a radial direction of the compressor impeller19. The circumferential direction of the turbocharger TC corresponds to a circumferential direction of the shaft15, a circumferential direction of the turbine wheel17, and a circumferential direction of the compressor impeller19.

An intake port21is formed in the compressor housing7. The intake port21is opened on the right side of the turbocharger TC. The intake port21is connected to an air cleaner (not shown). A diffuser flow passage23is defined by opposed surfaces of the bearing housing3and the compressor housing7. The diffuser flow passage23increases pressure of air. The diffuser flow passage23has an annular shape. The diffuser flow passage23communicates with the intake port21on a radially inner side through intermediation of the compressor impeller19.

Further, a compressor scroll flow passage25is formed in the compressor housing7. The compressor scroll flow passage25has an annular shape. The compressor scroll flow passage25is located, for example, on a radially outer side with respect to the diffuser flow passage23. The compressor scroll flow passage25communicates with an intake port of an engine (not shown) and the diffuser flow passage23. When the compressor impeller19rotates, the air is sucked from the intake port21into the compressor housing7. The sucked air is pressurized and accelerated in the course of flowing through blades of the compressor impeller19. The air having been pressurized and accelerated is increased in pressure in the diffuser flow passage23and the compressor scroll flow passage25. The air having been increased in pressure is guided to the intake port of the engine.

A discharge flow passage27, an accommodating portion29, a first turbine scroll flow passage31, and a second turbine scroll flow passage33are formed in the turbine housing5. The discharge flow passage27is opened on the left side of the turbocharger TC. The discharge flow passage27is connected to an exhaust-gas purification device (not shown). The discharge flow passage27communicates with the accommodating portion29. The discharge flow passage27is continuous with the accommodating portion29in the axial direction. The accommodating portion29accommodates the turbine wheel17. The first turbine scroll flow passage31and the second turbine scroll flow passage33are provided on a radially outer side with respect to the accommodating portion29.

The first turbine scroll flow passage31and the second turbine scroll flow passage33extend around the turbine wheel17on a radially outer side. The first turbine scroll flow passage31and the second turbine scroll flow passage33communicate with the accommodating portion29. The second turbine scroll flow passage33is arranged on a left side in the axial direction (that is, one side of the shaft15on which the turbine wheel17is mounted) with respect to the first turbine scroll flow passage31. A partition plate35is formed between the first turbine scroll flow passage31and the second turbine scroll flow passage33. The partition plate35partitions the first turbine scroll flow passage31and the second turbine scroll flow passage33in the axial direction. The first turbine scroll flow passage31and the second turbine scroll flow passage33communicate with an exhaust manifold of the engine (not shown). Exhaust gas exhausted from the exhaust manifold of the engine (not shown) is guided to the discharge flow passage27after the exhaust gas is sent to the accommodating portion29through the first turbine scroll flow passage31and the second turbine scroll flow passage33. The exhaust gas guided to the discharge flow passage27in the course of flowing causes the turbine wheel17to rotate.

A rotational force of the turbine wheel17is transmitted to the compressor impeller19through the shaft15. When the compressor impeller19rotates, the pressure of the air is increased as described above. In such a manner, the air is guided to the intake port of the engine.

FIG.2is a sectional view taken along the line A-A inFIG.1. The A-A cross section is a cross section that is orthogonal to the axial direction of the shaft15and passes through the first turbine scroll flow passage31. InFIG.2, the turbine wheel17is illustrated such that only an outer periphery thereof indicated by a circle is shown.

As illustrated inFIG.2, a first exhaust-air introduction port37is formed in the turbine housing5. The first exhaust-air introduction port37is open to the outside of the turbine housing5. The exhaust gas exhausted from the exhaust manifold of the engine (not shown) is introduced into the first exhaust-air introduction port37.

A first exhaust-air introduction passage39is formed between the first exhaust-air introduction port37and the first turbine scroll flow passage31. The first exhaust-air introduction passage39connects the first exhaust-air introduction port37and the first turbine scroll flow passage31to each other. The first exhaust-air introduction passage39is formed, for example, into a straight shape. The first exhaust-air introduction passage39guides the exhaust gas introduced from the first exhaust-air introduction port37, to the first turbine scroll flow passage31.

The first turbine scroll flow passage31communicates with the accommodating portion29through a first communication portion41. The first communication portion41is formed into an annular shape over the entire periphery of the accommodating portion29. The first turbine scroll flow passage31guides the exhaust gas introduced from the first exhaust-air introduction passage39, to the accommodating portion29through the first communication portion41. The first turbine scroll flow passage31extends around the turbine wheel17so as to be closer to the turbine wheel17as extending in a rotation direction RD of the turbine wheel17. A width of the first turbine scroll flow passage31in the radial direction decreases from an upstream side toward a downstream side.

A first tongue portion43is provided at a position facing a downstream end of the first turbine scroll flow passage31. The first tongue portion43partitions a downstream portion and an upstream portion of the first turbine scroll flow passage31.

FIG.3is a sectional view taken along the line B-B inFIG.1. The B-B cross section is a cross section that is orthogonal to the axial direction of the shaft15and passes through the second turbine scroll flow passage33. InFIG.3, similarly toFIG.2, the turbine wheel17is illustrated such that only an outer periphery thereof indicated by a circle is shown.

As illustrated inFIG.3, a second exhaust-air introduction port45is formed in the turbine housing5. The second exhaust-air introduction port45is open to the outside of the turbine housing5. The second exhaust-air introduction port45is arranged on the left side in the axial direction (that is, the one side of the shaft15on which the turbine wheel17is mounted) with respect to the first exhaust-air introduction port37. The first exhaust-air introduction port37and the second exhaust-air introduction port45are partitioned by the partition plate35in the axial direction. The exhaust gas exhausted from the exhaust manifold of the engine (not shown) is introduced into the second exhaust-air introduction port45.

A second exhaust-air introduction passage47is formed between the second exhaust-air introduction port45and the second turbine scroll flow passage33. The second exhaust-air introduction passage47connects the second exhaust-air introduction port45and the second turbine scroll flow passage33to each other. The second exhaust-air introduction passage47is formed, for example, into a straight shape. The second exhaust-air introduction passage47is arranged on the left side in the axial direction (that is, the one side of the shaft15on which the turbine wheel17is mounted) with respect to the first exhaust-air introduction passage39. The first exhaust-air introduction passage39and the second exhaust-air introduction passage47are partitioned by the partition plate35in the axial direction. The second exhaust-air introduction passage47guides the exhaust gas introduced from the second exhaust-air introduction port45, to the second turbine scroll flow passage33.

The second turbine scroll flow passage33communicates with the accommodating portion29through a second communication portion49. The second communication portion49is formed into an annular shape over the entire periphery of the accommodating portion29. The second communication portion49is arranged on the left side in the axial direction (that is, the one side of the shaft15on which the turbine wheel17is mounted) with respect to the first communication portion41. The first communication portion41and the second communication portion49are partitioned by the partition plate35in the axial direction. The second turbine scroll flow passage33guides the exhaust gas introduced from the second exhaust-air introduction passage47, to the accommodating portion29through the second communication portion49. The second turbine scroll flow passage33extends around the turbine wheel17so as to be closer to the turbine wheel17as extending in the rotation direction RD of the turbine wheel17. A width of the second turbine scroll flow passage33in the radial direction decreases from an upstream side toward a downstream side.

A second tongue portion51is provided at a position facing a downstream end of the second turbine scroll flow passage33. The second tongue portion51partitions a downstream portion and an upstream portion of the second turbine scroll flow passage33. A position of the first tongue portion43in the circumferential direction and a position of the second tongue portion51in the circumferential direction match each other.

FIG.4is a sectional view taken along the line C-C inFIG.2andFIG.3. The C-C cross section is a cross section that passes through the first tongue portion43and the second tongue portion51and includes a rotation axis of the turbine wheel17.

As illustrated inFIG.4, the turbine wheel17has a plurality of blade bodies17a. The plurality of blade bodies17aare provided at equal intervals in the circumferential direction. Each of the blade bodies17ais formed so as to extend radially outward from an outer peripheral surface of a hub extending on the rotation axis of the turbine wheel17. In an example ofFIG.4, a leading edge LE of the blade body17aextends in parallel with the rotation axis of the turbine wheel17. However, the leading edge LE may be inclined to the radially outer side as extending toward the left side in the axial direction (that is, the one side of the shaft15on which the turbine wheel17is mounted). The leading edge LE is a portion of an outer peripheral edge of the blade body17a, which is opposed to the first turbine scroll flow passage31and the second turbine scroll flow passage33. Exhaust gas flows into the accommodating portion29through the vicinity of the leading edge LE from the first turbine scroll flow passage31and the second turbine scroll flow passage33.

The first tongue portion43and the second tongue portion51are arranged on a radially outer side with respect to the leading edge LE of the blade body17aof the turbine wheel17. In the example ofFIG.4, portions of the first tongue portion43and the second tongue portion51facing the turbine wheel17extend in parallel with the rotation axis of the turbine wheel17. That is, the portions of the first tongue portion43and the second tongue portion51facing the turbine wheel17extend in parallel with the leading edge LE. When the first tongue portion43and the second tongue portion51are not particularly distinguished from each other, the first tongue portion43and the second tongue portion51are hereinafter simply referred to as “tongue portion.”

In the turbine T, when the blade body17aof the turbine wheel17passes through the vicinity of the tongue portion, a flow passage area formed by the blade body17aand the tongue portion is instantaneously narrowed, thereby causing flow contraction of gas. As a result, a force applied to the blade body17asignificantly fluctuates to cause blade vibration. In this embodiment, in order to reduce the blade vibration of the turbine wheel17, the shape of the tongue portion is devised.

FIG.5is a sectional view taken along the line D-D inFIG.4. The D-D cross section is a cross section that passes through the first tongue portion43and the second tongue portion51and is taken along the circumferential direction of the turbine wheel17. The D-D cross section is a sectional view when the first tongue portion43and the second tongue portion51are viewed in the radial direction from the turbine wheel17side. InFIG.5, the sectional view taken along the line D-D inFIG.4is illustrated, in which a direction indicated by the arrow L corresponds to an direction toward an upper side, and a direction indicated by the arrow R corresponds a direction toward a lower side.

In the turbine T, as illustrated inFIG.5, the first tongue portion43is inclined to the rotation direction RD of the turbine wheel17as extending in the direction indicated by the arrow L. That is, the first tongue portion43is inclined to the rotation direction RD as extending toward the one side of the shaft15on which the turbine wheel17is mounted. The second tongue portion51is inclined to a direction opposite to the rotation direction RD of the turbine wheel17as extending in the direction indicated by the arrow L. That is, the second tongue portion51is inclined to the direction opposite to the rotation direction RD as extending toward the one side of the shaft15on which the turbine wheel17is mounted.

As described above, in the turbine T, the first tongue portion43is inclined to one side of the turbine wheel17in the circumferential direction as extending toward the one side of the shaft15on which the turbine wheel17is mounted. The second tongue portion51is inclined to another side of the turbine wheel17in the circumferential direction as extending toward the above-mentioned one side. Thus, when each of the tongue portions is viewed in the radial direction from the turbine wheel17side, each of the tongue portions is inclined to the circumferential direction with respect to the axial direction of the turbine wheel17. Accordingly, regarding each of the tongue portions, when the blade bodies17aof the turbine wheel17pass through the vicinity of the tongue portion, a part of the tongue portion is sequentially opposed to the blade bodies17a.

As for the first tongue portion43, first, a portion of the first tongue portion43on a side of the direction indicated by the arrow R is opposed to the blade body17a. After that, the portion of the first tongue portion43opposed to the blade body17atransitions to a side of the direction indicated by the arrow L. As for the second tongue portion51, first, a portion of the second tongue portion51on a side of the direction indicated by the arrow L is opposed to the blade body17a. After that, the portion of the second tongue portion51opposed to the blade body17atransitions to a side of the direction indicated by the arrow R. Thus, regarding each of the tongue portions, the blade body17aof the turbine wheel17is prevented from simultaneously being opposed to an entire region of the tongue portion. Accordingly, when the blade body17aof the turbine wheel17passes through the vicinity of the tongue portion, a degree of instantaneous narrowing of the flow passage area formed by the blade body17aand the tongue portion is reduced, thereby preventing occurrence of the flow contraction of gas. Thus, the instantaneous fluctuation of the force applied to the blade body17ais suppressed, thereby reducing the blade vibration.

Further, in the turbine T, when each of the tongue portions is viewed in the radial direction from the turbine wheel17side, a direction in which the first tongue portion43is inclined with respect to the axial direction of the turbine wheel17and a direction in which the second tongue portion51is inclined with respect to the axial direction of the turbine wheel17are opposite to each other. Accordingly, a flow of gas flowing into the accommodating portion29of the turbine wheel17from the vicinity of the first tongue portion43and a flow of gas flowing into the accommodating portion29of the turbine wheel17from the vicinity of the second tongue portion51are plane symmetric with respect to a center plane of the partition plate35. The center plane of the partition plate35is a plane that passes through a center of the partition plate35in a thickness direction thereof and is orthogonal to the axial direction. Accordingly, an axial-direction component of the flow of gas flowing into the accommodating portion29of the turbine wheel17from the vicinity of the first tongue portion43and an axial-direction component of the flow of gas flowing into the accommodating portion29of the turbine wheel17from the vicinity of the second tongue portion51cancel out each other. Thus, occurrence of vortex flow in the vicinity of the blade body17ais prevented, and the instantaneous fluctuation of the force applied to the blade body17ais more effectively suppressed. As a result, the blade vibration is more effectively reduced.

The first tongue portion43and the second tongue portion51are not always required to be plane symmetric with respect to the center plane of the partition plate35. Even when the first tongue portion43and the second tongue portion51are not plane symmetric with respect to the center plane of the partition plate35, the axial-direction component of the flow of gas flowing into the accommodating portion29of the turbine wheel17from the vicinity of the first tongue portion43and the axial-direction component of the flow of gas flowing into the accommodating portion29of the turbine wheel17from the vicinity of the second tongue portion51at least partially cancel out each other. Thus, the blade vibration is reduced.

In particular, in the turbine T, the first tongue portion43is inclined to the rotation direction RD as extending toward the one side of the shaft15on which the turbine wheel17is mounted, and the second tongue portion51is inclined to the direction opposite to the rotation direction RD as extending toward the above-mentioned one side. Accordingly, regarding the axial direction, the gas flowing into the accommodating portion29of the turbine wheel17from the vicinity of the first tongue portion43is guided to the left side in the axial direction by the first tongue portion43. Meanwhile, regarding the axial direction, the gas flowing into the accommodating portion29of the turbine wheel17from the vicinity of the second tongue portion51is guided to a side opposite to the left side in the axial direction by the second tongue portion51. Thus, the gas flowing into the accommodating portion29of the turbine wheel17from the vicinity of each of the tongue portions flows into a center side of the blade body17ain the axial direction. As a result, aerodynamic performance is improved.

Description is given of inclination angles of the first tongue portion43and the second tongue portion51with respect to the axial direction when viewed in the radial direction of the turbine wheel17. InFIG.5, there are illustrated an inclination angle θ1 of the first tongue portion43with respect to the axial direction when viewed in the radial direction of the turbine wheel17and an inclination angle θ2 of the second tongue portion51with respect to the axial direction when viewed in the radial direction of the turbine wheel17.

The inclination angle θ1 and the inclination angle θ2 substantially match each other. As the inclination angles θ1 and θ2 are larger, when the blade body17aof the turbine wheel17passes through the vicinity of the tongue portion, the degree of instantaneous narrowing of the flow passage area formed by the blade body17aand the tongue portion is more effectively reduced, thereby preventing occurrence of the flow contraction of gas more effectively. Thus, the instantaneous fluctuation of the force applied to the blade body17ais more effectively suppressed, and the effect of reducing the blade vibration is improved. Meanwhile, when the inclination angles θ1 and θ2 are excessively large, flow field in the accommodating portion29of the turbine wheel17significantly deviates from an expected state. Thus, there is a fear in that the aerodynamic performance is degraded.

In view of suppressing the degradation of the aerodynamic performance, for example, it is preferred that each of the inclination angles θ1 and θ2 be equal to or less than an angle obtained by dividing 360° by the number of the blade bodies17aof the turbine wheel17. As the number of the blade bodies17ais larger, time lag between timings at which the blade bodies17aadjacent to each other are opposed to the tongue portion becomes shorter. With the inclination angles θ1 and θ2 set as described above, the inclination angles θ1 and θ2 can be made smaller as the number of the blade bodies17ais larger. Accordingly, time required for each of the blade bodies17ato pass through the tongue portion is prevented from relatively excessively becoming longer with respect to the above-mentioned time lag. Thus, the flow field in the accommodating portion29of the turbine wheel17is prevented from significantly deviating from the expected state, thereby suppressing the degradation of the aerodynamic performance.

However, each of the inclination angles θ1 and θ2 is not required to be equal to or less than an angle obtained by dividing 360° by the number of the blade bodies17aof the turbine wheel17. Further, the inclination angle θ1 and the inclination angle θ2 may be different from each other.

In the above, there has been described an example in which the each of the tongue portions is not inclined to the radial direction with respect to the axial direction of the turbine wheel17when viewed in the circumferential direction of the turbine wheel17. However, at least one of the first tongue portion43or the second tongue portion51may be inclined to the radial direction with respect to the axial direction of the turbine wheel17when viewed in the circumferential direction of the turbine wheel17.

FIG.6is a sectional view taken along the line D-D in a turbine T1according to a modification example. In the turbine T1, as compared to the turbine T described above, inclination directions of the first tongue portion43and the second tongue portion51are different from those given in the turbine T.

In the turbine T1, as illustrated inFIG.6, the first tongue portion43is inclined to a direction opposite to the rotation direction RD of the turbine wheel17as extending in the direction indicated by the arrow L. That is, the first tongue portion43is inclined to the direction opposite to the rotation direction RD as extending toward the one side of the shaft15on which the turbine wheel17is mounted. The second tongue portion51is inclined to the rotation direction RD of the turbine wheel17as extending in the direction indicated by the arrow L. That is, the second tongue portion51is inclined to the rotation direction RD as extending toward the one side of the shaft15on which the turbine wheel17is mounted.

As described above, in the turbine T1, similarly to the turbine T described above, the first tongue portion43is inclined to the one side of the turbine wheel17in the circumferential direction as extending toward the one side of the shaft15on which the turbine wheel17is mounted. The second tongue portion51is inclined to the another side of the turbine wheel17in the circumferential direction as extending toward the above-mentioned one side. Thus, similarly to the above-mentioned turbine T, the effect of reducing the blade vibration is achieved.

In particular, in the turbine T1, the first tongue portion43is inclined to the direction opposite to the rotation direction RD as extending toward the one side of the shaft15on which the turbine wheel17is mounted. The second tongue portion51is inclined to the rotation direction RD as extending toward the above-mentioned one side. Accordingly, in portions of the first turbine scroll flow passage31and the second turbine scroll flow passage33adjacent to the tongue portions on an upstream side (portions on a left side with respect to the first tongue portion43and the second tongue portion51inFIG.6), an angle formed by each of the tongue portions and a surface opposed to the partition plate35among inner surfaces of each of the turbine scroll flow passages becomes an obtuse angle. Thus, on the upstream side of each of the turbine scroll flow passages that is close to an engine exhaust air and is to be in contact with gas having more energy, a crack is prevented from occurring in a boundary portion between each of the tongue portions and each of the turbine scroll flow passages.

Also in the turbine T1, similarly to the turbine T1, each of the inclination angles θ1 and θ2 may be equal to or less than an angle obtained by dividing 360° by the number of the blade bodies17aof the turbine wheel17, or may not be equal to or less than the above-mentioned angle. Further, the inclination angles θ1 and θ2 may substantially match each other or may be different from each other. In addition, each of the tongue portions is not required to be inclined to the radial direction with respect to the axial direction of the turbine wheel17when viewed in the circumferential direction of the turbine wheel17. At least one of the first tongue portion43or the second tongue portion51may be inclined to the radial direction with respect to the axial direction of the turbine wheel17.

An embodiment of the present disclosure has been described above with reference to the attached drawings, but, needless to say, the present disclosure is not limited to the above-mentioned embodiment. It is apparent that those skilled in the art may arrive at various alternations and modifications within the scope of claims, and those examples are construed as naturally falling within the technical scope of the present disclosure.

In the above, the example in which the turbine T is mounted to the turbocharger TC has been described. However, the turbine T may be mounted to devices other than the turbocharger TC, such as a power generator.

The present disclosure can reduce the blade vibration of the turbine wheel. Thus, for example, the present disclosure can contribute to Goal 7 “Ensure access to affordable, reliable, sustainable and modern energy for all” and Goal 9 “Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation” of the Sustainable Development Goals (SDGs).