JP2021059996A - Turbocharger - Google Patents

Abstract

To suppress rise of a bubble fraction in oil.SOLUTION: A turbocharger includes a bearing housing 30 in which an insertion hole 31 is defined. Into the insertion hole 31, a cylindrical float bearing 70 is inserted. Into the float bearing 70, a shaft 60 is inserted. The shaft 60 includes a shaft body 61 both ends of which are protruded from the float bearing 70. From an outer peripheral face at an end of the shaft body 61, a slinger 62 is protruded toward a radial outside. In the bearing housing 30, an oil spray space 32, an oil discharge space 33 communicating from the oil spray space 32 to an external of the bearing housing 30, and an oil passage 35 extending from a site on a center side further than an end of the float bearing 70 in the axial direction, out of the inner peripheral face of the insertion hole 31, to the oil discharge space 33 are defined so as to encircle the slinger 62 from the radial outside.SELECTED DRAWING: Figure 2

Description

The present invention relates to a turbocharger.

The turbocharger of Patent Document 1 includes a shaft that connects a turbine wheel and a compressor wheel, and a bearing housing for accommodating the shaft. The bearing housing has a tubular shape as a whole, and a cylindrical float bearing is inserted inside the bearing housing. The shaft body of the shaft is inserted inside the float bearing. Both ends of the shaft body in the axial direction project to the outside of the float bearing. A slinger protrudes outward in the radial direction from the outer peripheral surface at the end of the shaft body. The slinger extends over the entire circumferential direction of the shaft body. Further, in the bearing housing, an oil scattering space is partitioned so as to surround the slinger of the shaft from the outside in the radial direction. Further, the bearing housing is divided into an oil discharge space that communicates the oil scattering space with the outside of the bearing housing.

Japanese Unexamined Patent Publication No. 2014-025396

In the turbocharger of Patent Document 1, oil is supplied between the inner peripheral surface of the float bearing and the outer peripheral surface of the shaft, and between the outer peripheral surface of the float bearing and the inner peripheral surface of the bearing housing. If the oils supplied to these two locations merge at a high flow velocity, they may collide with each other at the time of the merge and the bubble ratio in the oil may increase.

The turbocharger for solving the above problems includes a bearing housing in which an insertion hole is partitioned, a tubular float bearing inserted in the insertion hole, and a turbine wheel inserted inside the float bearing. A turbocharger including a shaft connecting the compressor wheel and a shaft, the shaft having a central portion in the axial direction inserted inside the float bearing and both end portions in the axial direction protruding from the float bearing. The bearing housing includes an annular slinger that protrudes radially outward from the outer peripheral surface at the end of the shaft body, and oil splashes are arranged so as to surround the slinger from the radial outside in the bearing housing. The oil from the space, the oil discharge space communicating from the oil scattering space to the outside of the bearing housing, and the inner peripheral surface of the insertion hole, in the axial direction from the center side of the end of the float bearing. The oil passage extending to the discharge space is partitioned.

According to the above configuration, the oil supplied between the outer peripheral surface of the shaft and the inner peripheral surface of the float bearing reaches the oil discharge space through the oil scattering space. On the other hand, since the oil passage is connected to the center side of the end of the float bearing, most of the oil supplied between the outer peripheral surface of the float bearing and the inner peripheral surface of the insertion hole in the bearing housing is It reaches the oil discharge space through the oil passage without reaching the slinger and the oil scattering space. Since they pass through different spaces before reaching the oil discharge space in this way, they merge after the flow velocity of the oil is appropriately reduced. Therefore, it is possible to prevent the oil from colliding with each other at a high flow velocity and increasing the bubble ratio.

Schematic diagram of an internal combustion engine. Sectional drawing of the peripheral structure of a bearing housing.

Hereinafter, embodiments will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1, the internal combustion engine 100 includes an intake passage 11 through which intake air from the outside of the internal combustion engine 100 flows. A cylinder 12 for mixing fuel with intake air and burning the fuel is connected to the intake passage 11. An exhaust passage 13 for exhausting exhaust gas from the cylinder 12 is connected to the cylinder 12.

The internal combustion engine 100 includes a turbocharger 20 for compressing intake air by utilizing the flow of exhaust gas. The compressor housing 21 of the turbocharger 20 is attached in the middle of the intake passage 11. Further, the turbine housing 22 of the turbocharger 20 is attached in the middle of the exhaust passage 13. The compressor housing 21 and the turbine housing 22 are connected via a bearing housing 30 in the turbocharger 20. As described above, the turbocharger 20 as a whole is attached so as to straddle the intake passage 11 and the exhaust passage 13.

Inside the turbine housing 22, a turbine wheel 52 that rotates due to the flow of exhaust gas is housed. One end of the shaft 60 is connected to the turbine wheel 52. The central portion of the shaft 60 in the axial direction is housed inside the bearing housing 30 and is rotatably supported. A compressor wheel 51 is connected to the other end of the shaft 60. The compressor wheel 51 is housed inside the compressor housing 21.

Next, the bearing housing 30 and its related configuration in the turbocharger 20 will be specifically described. In the following description, it is assumed that the internal combustion engine 100 is mounted on the vehicle, and the vertical direction of the vehicle is the vertical direction of the turbocharger 20.

As shown in FIG. 2, the bearing housing 30 has a cylindrical shape as a whole. A substantially cylindrical insertion hole 31 is defined in the radial center of the bearing housing 30. The insertion hole 31 penetrates the bearing housing 30 in the axial direction. Oil is introduced from the outside into the central portion of the insertion hole 31 in the axial direction via an oil introduction path (not shown).

A substantially cylindrical float bearing 70 is inserted inside the insertion hole 31 in the bearing housing 30. The axial dimension of the float bearing 70 is smaller than the axial dimension of the bearing housing 30. The float bearing 70 is arranged at the center of the bearing housing 30 in the axial direction. That is, both ends of the float bearing 70 do not project to the outside of the bearing housing 30.

The outer diameter of the float bearing 70 is slightly smaller than the inner diameter of the insertion hole 31. A positioning pin (not shown) is inserted into the float bearing 70 from the outside in the radial direction. By this pin, the float bearing 70 is non-rotatable and axially positioned with respect to the bearing housing 30.

On the outer peripheral surface of one end of the float bearing 70 on the turbine wheel 52 side, the groove 71 is recessed inward in the radial direction. The groove portion 71 extends in the entire circumferential direction of the float bearing 70, and has an annular shape as a whole.

Oil is introduced between the outer peripheral surface of the float bearing 70 and the inner peripheral surface of the insertion hole 31 via the oil introduction path of the bearing housing 30. Therefore, the float bearing 70 is supported by the bearing housing 30 in a state of floating in the oil introduced between the outer peripheral surface of the float bearing 70 and the inner peripheral surface of the insertion hole 31. The float bearing 70 is provided with an oil supply hole (not shown) penetrating in the radial direction. Oil is supplied to the inside of the float bearing 70 from the radial outside of the float bearing 70 through the oil supply hole.

The shaft body 61 of the shaft 60 is inserted inside the float bearing 70. The shaft body 61 has a circular rod shape. The outer diameter of the shaft body 61 is slightly smaller than the inner diameter of the float bearing 70. Further, the axial dimension of the shaft body 61 is larger than the axial dimension of the float bearing 70. In the axial direction of the bearing housing 30, the central portion of the shaft body 61 is inserted into the float bearing 70, and both ends of the shaft body 61 project outward from the float bearing 70. Oil is introduced between the outer peripheral surface of the shaft body 61 and the inner peripheral surface of the float bearing 70 through the oil supply hole of the float bearing 70. The shaft body 61 is rotatably supported via oil supplied between the outer peripheral surface of the shaft body 61 and the inner peripheral surface of the float bearing 70.

From one end of the shaft body 61 on the turbine housing 22 side, a columnar large diameter portion 63 extends toward one end side in the axial direction. The large diameter portion 63 is coaxial with the shaft body 61. The outer diameter of the large diameter portion 63 is larger than the outer diameter of the shaft body 61 and smaller than the inner diameter of the insertion hole 31 in the bearing housing 30. A part of the large diameter portion 63 protrudes from the bearing housing 30 toward the turbine housing 22.

An annular seal ring 81 is attached to the outer peripheral surface of the large diameter portion 63 of the shaft 60. The inner diameter of the seal ring 81 is substantially the same as the outer diameter of the large diameter portion 63. Further, the outer diameter of the seal ring 81 is substantially the same as the inner diameter of the insertion hole 31. Therefore, the seal ring 81 suppresses the exhaust gas flowing inside the turbine housing 22 from leaking into the bearing housing 30. Further, the turbine wheel 52 described above is connected to the end surface of the large diameter portion 63 of the shaft 60.

A slinger 62 projects radially outward from the outer peripheral surface of one end of the shaft body 61 on the turbine wheel 52 side. The slinger 62 extends in the entire circumferential direction of the shaft body 61, and has an annular shape as a whole.

As shown in FIG. 2, the bearing housing 30 is partitioned with an oil scattering space 32 so as to surround the slinger 62 from the outside in the radial direction. The oil scattering space 32 has a circular shape as a whole when viewed from the axial direction of the bearing housing 30.

Further, the bearing housing 30 is partitioned with an oil discharge space 33 connected to the oil scattering space 32. The oil discharge space 33 is arranged below the oil scattering space 32 and the insertion hole 31. Further, the dimension of the oil discharge space 33 in the axial direction of the bearing housing 30 is larger than the dimension of the float bearing 70 in the axial direction. Specifically, the oil discharge space 33 extends from the turbine wheel 52 side to the compressor wheel 51 side with respect to the slinger 62.

The oil discharge space 33 expands so as to be located on the lower side toward the center in the axial direction of the bearing housing 30. The lowermost portion of the oil discharge space 33 at the central portion in the axial direction is a discharge port 33a communicating with the outside of the bearing housing 30. Therefore, the oil discharge space 33 communicates from the oil scattering space 32 to the outside of the bearing housing 30.

The bearing housing 30 is partitioned with an oil passage 35 extending from a portion on the central side of the end of the float bearing 70 to the oil discharge space 33 in the axial direction of the inner peripheral surface of the insertion hole 31. The oil passage 35 is located below the insertion hole 31. The upper end of the oil passage 35 is opened at a position facing the groove 71 of the float bearing 70. The oil passage 35 extends linearly and diagonally toward the center side in the axial direction of the shaft 60 toward the lower side. The discharge port 33a of the oil discharge space 33 is located on the central axis J of the oil passage 35. However, in this embodiment, the center of the discharge port 33a is located closer to the turbine wheel 52 than the central axis J of the oil passage 35.

The operation of this embodiment will be described.
A part of the oil circulating in the entire internal combustion engine 100 is supplied between the inner peripheral surface of the float bearing 70 and the outer peripheral surface of the shaft body 61, and flows to the end side of the shaft body 61. Then, when the oil reaches the slinger 62 of the shaft 60, as shown by the solid arrow in FIG. 2, it is blown outward in the radial direction by centrifugal force and scattered in the oil scattering space 32. The oil scattered in the oil scattering space 32 propagates downward in the oil discharge space 33 according to gravity, and is discharged from the discharge port 33a to the outside of the bearing housing 30.

On the other hand, the oil supplied between the inner peripheral surface of the insertion hole 31 and the outer peripheral surface of the float bearing 70 flows to the end side of the float bearing 70. Here, the oil flowing toward the turbine wheel 52 in the axial direction of the shaft 60 is trapped in the groove 71 before reaching the end of the float bearing 70. The oil trapped in the groove 71 is guided to the oil passage 35 by gravity as shown by the broken line arrow in FIG. Then, the oil reaches the oil discharge space 33 through the oil passage 35, and is discharged from the discharge port 33a to the outside of the bearing housing 30.

The effect of this embodiment will be described.
(1) The oil that reaches the slinger 62 from between the inner peripheral surface of the float bearing 70 and the outer peripheral surface of the shaft body 61 is blown into the oil scattering space 32 at an appropriate flow velocity by centrifugal force. Therefore, if a large amount of oil is present in the oil scattering space 32, the oil blown off from the slinger 62 may collide with the oil in the oil scattering space 32 to generate bubbles. In this respect, in the above embodiment, most of the oil supplied between the inner peripheral surface of the insertion hole 31 and the outer peripheral surface of the float bearing 70 passes through the oil passage 35 without passing through the oil scattering space 32. It leads to the oil discharge space 33. Therefore, the amount of oil that reaches the oil scattering space 32 can be reduced. Therefore, it is possible to prevent the scattered oil from colliding with a large amount of oil existing in the oil scattering space 32 to generate bubbles.

(2) In the above embodiment, the flow velocity of the oil scattered in the oil scattering space 32 decreases while traveling along the inner walls of the oil scattering space 32 and the oil discharge space 33. Similarly, the flow velocity of the oil guided into the oil passage 35 decreases while traveling along the inner walls of the oil passage 35 and the oil discharge space 33. Therefore, when the oil from the oil scattering space 32 and the oil from the oil passage 35 merge in the oil discharge space 33, the flow velocity of the oil should be reduced accordingly. Therefore, when these oils merge in the oil discharge space 33, they do not collide with each other to generate a large amount of bubbles.

(3) In the above embodiment, the float bearing 70 is provided with a groove 71, and oil can be trapped in the groove 71. Then, the trapped oil flows into the oil passage 35 that opens toward the groove 71. Therefore, most of the oil supplied between the inner peripheral surface of the insertion hole 31 and the outer peripheral surface of the float bearing 70 can be guided to the oil passage 35.

(4) In the above embodiment, the discharge port 33a is located on the central axis J of the oil passage 35, and if the oil flows linearly from the oil passage 35 as it is, it goes out through the discharge port 33a as it is. It is discharged. Therefore, it is possible to prevent the oil flowing out from the oil passage 35 from colliding with the oil in the oil discharge space 33 to generate bubbles. Moreover, in the above embodiment, the center of the discharge port 33a is located closer to the turbine wheel 52 than the central axis J of the oil passage 35. That is, as shown by the broken line arrow in FIG. 2, the position of the discharge port 33a is set in consideration of the fact that the oil from the oil passage 35 will flow slightly downward from the central axis J due to gravity. ing. Therefore, the oil from the oil passage 35 easily reaches the discharge port 33a directly.

This embodiment can be modified and implemented as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
-In the above embodiment, the extension configuration of the oil passage 35 is not limited to the example of the above embodiment. For example, the oil passage 35 is not limited to the structure extending linearly, and may extend so as to be curved. Further, for example, the discharge port 33a may not be located on the central axis J of the oil passage 35.

-In the above embodiment, a plurality of oil passages 35 may be provided. When a plurality of oil passages 35 are provided, the oil passages 35 may be arranged side by side in the circumferential direction of the shaft 60, or may be arranged side by side in the axial direction of the shaft 60.

-In the above embodiment, the groove portions 71 may be arranged side by side in the axial direction of the shaft 60. In this case, it is preferable that the oil passage 35 is communicated with the groove portion 71.
-In the above embodiment, the groove 71 may be omitted. Even if the groove 71 is omitted, if the oil passage 35 is open on the center side of the end of the float bearing 70, the oil between the inner peripheral surface of the insertion hole 31 and the outer peripheral surface of the float bearing 70 can be removed. It flows into the oil passage 35.

In the above embodiment, the shape of the oil discharge space 33 of the bearing housing 30 may be any shape as long as the oil can be discharged to the outside from the oil passage 35 or the oil scattering space 32. When the position of the discharge port 33a is changed from the example of the above embodiment, it is preferable to change the extension direction and position of the oil passage 35 accordingly.

The configuration relating to the groove portion 71 of the float bearing 70 and the oil passage 35 of the bearing housing 30 of the above embodiment may be adopted as the configuration on the compressor wheel 51 side. In this case as well, the same effect as that of the above embodiment can be obtained.

11 ... Intake passage, 12 ... Cylinder, 13 ... Exhaust passage, 20 ... Turbocharger, 21 ... Compressor housing, 22 ... Turbine housing, 30 ... Bearing housing, 31 ... Insert hole, 32 ... Oil scattering space, 33 ... Oil discharge space , 33a ... Discharge port, 35 ... Oil passage, 51 ... Compressor wheel, 52 ... Turbine wheel, 60 ... Shaft, 61 ... Shaft body, 62 ... Slinger, 63 ... Large diameter part, 70 ... Float bearing, 71 ... Groove part, 81 ... Seal ring, 100 ... Internal combustion engine.

Claims (1)

Bearing housing with insertion holes inside and
A tubular float bearing inserted into the insertion hole and
A turbocharger that is inserted inside the float bearing and includes a shaft that connects a turbine wheel and a compressor wheel.
The shaft
A shaft body in which the central portion in the axial direction is inserted inside the float bearing and both ends in the axial direction protrude from the float bearing.
An annular slinger that protrudes radially outward from the outer peripheral surface at the end of the shaft body is provided.
The bearing housing has
An oil scattering space arranged so as to surround the slinger from the outside in the radial direction,
An oil discharge space that communicates from the oil scattering space to the outside of the bearing housing,
A turbocharger in which an oil passage extending from a portion central to the end of the float bearing to the oil discharge space in the axial direction of the inner peripheral surface of the insertion hole is partitioned.

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