turbocharger

Abstract

To provide a turbocharger capable of improving NV characteristics in a constitution having a turbine wheel formed of TiAl material.SOLUTION: A turbocharger 10 includes a shaft 12 having one end 12a and the other end 12b and rotatably supported by a rolling bearing 14, an impeller 30 fixed to the one end 12a side of the shaft 12, a turbine wheel 20 fixed to the other end 12b side of the shaft 12, and a fixture 36 attached to the one end 12a side of the shaft 12 so as to fix the impeller 30 to the shaft 12. The turbine wheel 20 is formed of TiAl material, and the fixture 36 includes a portion positioned on a side opposite from a side on which the other end 12b is positioned with respect to the one end 12a.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a turbocharger.

Background Art

[0002] As a conventional turbocharger, International Publication No. 2014 / 128930 (Patent Document 1) discloses a configuration in which an impeller is fixed to one end of a turbine rotor shaft (shaft) rotatably supported by bearings with a mounting nut, and a turbine wheel made of a TiAl material is fixed to the other end of the turbine rotor shaft. One end of the shaft passes through the mounting nut and protrudes beyond the mounting nut.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, the turbine wheel is formed of an Inconel material. However, when the turbine wheel is formed of a TiAl material as described in Patent Document 1, the weight of the turbine wheel is reduced and the natural frequency of the rotating body is increased. When the natural frequency of the rotating body increases, the vibration becomes large and the NV characteristics deteriorate.

[0005] When the shaft is supported by a sliding bearing, it is possible to reduce the natural frequency by thinning a part of the shaft to reduce the rigidity of the shaft. However, when the shaft is supported by a rolling bearing, a spacer is already formed around the shaft or an inner ring exists. For this reason, it is difficult to sufficiently reduce the natural frequency even if a part of the shaft is thinned. Therefore, it is difficult to improve the NV characteristics.

[0006] The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a turbocharger capable of improving NV characteristics in a configuration including a turbine wheel formed of a TiAl material.

Means for Solving the Problems

[0007] The turbocharger according to the present disclosure includes a shaft having one end and the other end and rotatably supported by a rolling bearing, an impeller fixed to the one end side of the shaft, a turbine wheel fixed to the other end side of the shaft, and a fixture attached to the one end side of the shaft for fixing the impeller to the shaft. The turbine wheel is made of a TiAl material. The fixture includes a portion located on the side opposite to the side where the other end is located with respect to the one end.

[0008] In the turbocharger according to the present disclosure, the center of gravity position of the fixture may be located on the side opposite to the side where the other end is located with respect to the one end.

[0009] In the turbocharger according to the present disclosure, the fixture may have a portion covering the one end of the shaft.

[0010] In the turbocharger according to the present disclosure, the portion of the fixture covering the one end of the shaft may have a tapered shape that tapers as it goes toward the opposite side.

[0011] In the turbocharger according to the present disclosure, the fixture may be provided with a cutout portion. In this case, at least a part of the cutout portion may be provided in a portion of the fixture located on the side opposite to the side where the other end is located with respect to the one end.

Advantages of the Invention

[0012] According to the present disclosure, in a configuration including a turbine wheel formed of a TiAl material, a turbocharger capable of improving NV characteristics can be provided.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[23] ]

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments shown below, the same or common parts are denoted by the same reference numerals in the drawings, and the description thereof will not be repeated.

[0015] (Embodiment 1) FIG. 1 is a schematic cross-sectional view showing a turbocharger according to Embodiment 1. With reference to FIG. 1, the turbocharger 10 according to Embodiment 1 will be described. [[ID=

[33] ]

[0016] As shown in FIG. 1, the turbocharger 10 includes a shaft 12, a turbine wheel 20, an impeller 30, and a fixture 36.

[0017] The shaft 12 is rotatably supported by a rolling bearing 14. The shaft 12 rotates around the rotation axis R. The rolling bearing 14 is provided in the center housing 11. The shaft 12 has one end 12a and the other end 12b. An impeller 30 is fixed to one end 12a side of the shaft 12. A turbine wheel 20 is fixed to the other end 12b side of the shaft 12. The impeller 30 and the turbine wheel 20 rotate integrally with the shaft 12.

[0018] The turbine wheel 20 is made of a TiAl material. As a result, the weight of the turbine wheel 20 can be reduced as compared with the case where it is made of an Inconel material.

[0019] The turbine wheel 20 rotates in response to the exhaust of the internal combustion engine. The turbine wheel 20 is housed in a turbine housing 21. The turbine housing 21 is assembled to the center housing 11. A scroll passage 22 that extends in a spiral shape along the outer circumference of the turbine wheel 20 is formed in the turbine housing 21. The exhaust discharged from the internal combustion engine is introduced into this scroll passage 22. The exhaust that has obtained rotational force by the scroll passage 22 is blown against the blades 24 of the turbine wheel 20 through an inlet 23 formed on the inner surface of the scroll passage 22, as indicated by an arrow AR1 in FIG. 1. Thereby, the turbine wheel 20 is rotated. Note that the exhaust blown against the turbine wheel 20 is discharged into the exhaust pipe of the internal combustion engine through an exhaust port 25 that opens on the front side of the turbine wheel 20.

[0020] The impeller (compressor wheel) 30 is housed inside a compressor housing 31 indicated by a dashed-dotted line in FIG. 1. The compressor housing 31 is assembled to the center housing 11. In the compressor housing 31, an intake port 32 for introducing intake air is formed on the front side of the impeller 30. In the compressor housing 31, a compressor passage 34 that extends in a spiral shape is formed on the outer circumference of the impeller 30. This compressor passage 34 is connected to a discharge port 33 that opens to the outer peripheral portion of the impeller 30.

[0021] In the turbocharger 10, when the rotation of the turbine wheel 20 is transmitted by the shaft 12 and the impeller 30 rotates, intake air is sucked through the intake port 32. The intake air thus sucked is sent to the discharge port 33 by the blades 35 provided on the impeller 30 as shown by the arrow AR2 in the figure. The intake air is compressed by being forcibly sent from the discharge port 33 into the compressor passage 34. Then, the intake air thus compressed is sent to the cylinder of the internal combustion engine, so that supercharging of the internal combustion engine is performed.

[0022] The fixture 36 is attached to the one end 12a side of the shaft 12 and fixes the impeller 30 to the shaft 12. The fixture 36 is attached to the shaft 12, for example, by screwing into a screw groove provided on the peripheral surface of the one end 12a side of the shaft 12.

[0023] The fixture 36 includes a portion located on the side opposite to the side where the other end 12b is located with respect to the one end 12a of the shaft 12. The center of gravity position O of the fixture 36 is located on the side opposite to the side where the other end is located at 12b with respect to the one end 12a.

[0024] The fixture 36 has a portion that covers the one end 12a of the shaft 12. The portion that covers the one end 12a has a tapered shape as it goes toward the side opposite to the side where the other end 12b is located with respect to the one end 12a. More specifically, the fixture 36 has a bullet shape with a tapered tip side.

[0025] More specifically, the fixture 36 has a first portion 361 and a second portion 362. The second portion 362 has a larger diameter than the first portion 361. The second portion 362 is located on the other end 12b of the shaft 12 with respect to the first portion 361. The second portion 362 may have a polygonal cylindrical shape. For example, the second portion 362 may have a hexagonal cylindrical shape. The first portion 361 is located on the tip side of the fixture 36. The first portion 361 has a tapered shape as described above and covers the one end 12a.

[0026] Generally, in the turbocharger 10, since the turbine wheel 20 is made of a TiAl material, the natural frequencies of the rotating body including the shaft 12, the impeller 30, and the turbine wheel 20 increase when there is no particular measure.

[0027] Here, in the present embodiment, the fixture 36 includes a portion located on the side opposite to the side where the other end 12b is located with respect to one end 12a of the shaft 12, thereby deliberately increasing the weight of the fixture 36. As a result, the increase in the natural frequencies is suppressed, and the NV characteristics can be improved. In particular, in the primary bending mode in which the shaft 12 bends and the impeller 30 swings around, the change in the weight of the fixture 36 greatly contributes to the change amount of the natural frequencies. Therefore, by slightly increasing the mass of the fixture 36, the natural frequencies can be significantly reduced.

[0028] Furthermore, as described above, since the center of gravity position O of the fixture 36 is located on the side opposite to the side where the other end 12b is located with respect to one end 12a of the shaft 12, the natural frequencies can be more reliably reduced.

[0029] In addition, since the fixture 36 has a portion that covers one end 12a of the shaft 12, the one end 12a can be protected, and the weight of the fixture 36 can be increased by this portion.

[0030] In addition, in the fixture 36, the portion that covers one end 12a of the shaft 12 has a tapered shape as it goes toward the side opposite to the side where the other end 12b is located with respect to the one end 12a, so that the flow resistance of the intake air sucked through the suction port 32 can be suppressed.

[0031] (Modification 1) FIG. 2 is a schematic view showing a fixture according to Modification 1. With reference to FIG. 2, the fixture 36V according to Modification 1 will be described.

[0032] The fixture 36V has a different shape compared to the fixture 36. In the fixture 36, the second part 362V has a cylindrical shape and surrounds the periphery of one end 12a side of the shaft 12. The second part 362V has, for example, a cylindrical shape. The first part 361V is provided so as to close the tip opening of the second part 362. The first part 361V has a polygonal prism shape. Although not particularly limited, the first part 361V may have a hexagonal prism shape. Such a fixture 36V may be used. Also in this case, substantially the same effects as those in the first embodiment can be obtained.

[0033] (Embodiment 2) FIG. 3 is a schematic cross-sectional view showing the turbocharger according to the second embodiment. With reference to FIG. 3, the turbocharger 10A according to the second embodiment will be described.

[0034] As shown in FIG. 3, the turbocharger 10A according to the second embodiment is different from the turbocharger 10 according to the first embodiment in that a cutout portion 363 is provided in the fixture 36. Other configurations are substantially the same.

[0035] The cutout portion 363 is provided in a portion of the fixture 36 located on the side opposite to the side where the other end 12b is located with respect to the one end 12a. By providing such a cutout portion 363, the rotational balance of the rotating body can be adjusted.

[0036] (Embodiment 3) FIG. 4 is a schematic cross-sectional view showing the turbocharger according to the third embodiment. With reference to FIG. 4, the turbocharger 10B according to the third embodiment will be described.

[0037] As shown in FIG. 4, the turbocharger 10B according to the third embodiment is different from the turbocharger 10 according to the first embodiment in the shape of the fixture 36B. Other configurations are substantially the same.

[0038] The fixture 36B has a cylindrical shape and has a through-hole 367h that penetrates in the axial direction. One end 12a side of the shaft 12 is inserted into the through-hole 367h. When viewed from the above axial direction, the one end 12a is located within the through-hole 367h and is exposed to the outside. Note that the tip of the fixture 36B protrudes from the one end 12a toward the side opposite to the side where the impeller 30 is located with respect to the fixture 36B. The through-hole 367h may have a shape in which the diameter becomes smaller as it goes from the tip side toward the one end 12a. The through-hole 367h has a constant diameter from the one end 12a to the impeller 30.

[0039] Even in such a configuration, the mass of the fixture 36B can be increased, and substantially the same effects as those in the first embodiment can be obtained.

[0040] As described above, all the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is shown by the scope of the claims, and all changes within the meaning and scope equivalent to the scope of the claims are included.

Explanation of Reference Numerals

[0041] 10, 10A, 10B Turbocharger, 11 Center housing, 12 Shaft, 12a One end, 12b The other end, 14 Bearing, 20 Turbine wheel, 21 Turbine housing, 22 Scroll passage, 23 Inlet, 25 Outlet, 30 Impeller, 31 Compressor housing, 32 Suction port, 33 Discharge port, 34 Compressor passage, 35 Blade, 36, 36B, 36V Fixture, 361, 361V First part, 362, 362V Second part, 363 Relief portion, 367h Through-hole, O Center of gravity position.

Claims

1. A shaft having one end and the other end, and rotatably supported by a rolling bearing; An impeller fixed to the one end side of the shaft; A turbine wheel fixed to the other end side of the shaft; A fixture attached to the one end side of the shaft for fixing the impeller to the shaft, and comprising: The turbine wheel is made of a TiAl material; The fixture includes a portion located on a side opposite to a side where the other end is located with respect to the one end, a turbocharger.

2. The turbocharger according to claim 1, wherein a center of gravity position of the fixture is located on a side opposite to a side where the other end is located with respect to the one end.

3. The turbocharger according to claim 1, wherein the fixture has a portion covering the one end of the shaft.

4. The turbocharger according to claim 3, wherein the portion of the fixture covering the one end of the shaft has a tapered shape as it goes toward the opposite side.

5. The fixture is provided with a cutout portion; The turbocharger according to any one of claims 1 to 4, wherein at least a part of the cutout portion is provided in a portion of the fixture located on a side opposite to a side where the other end is located with respect to the one end.

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