Turbocharger

Abstract

This turbocharger comprises: a bearing housing 2 that accommodates a bearing 9; a refrigerant channel 100 that is formed in the bearing housing 2, is disposed around the periphery of the bearing 9 when viewed in the axial direction of the bearing 9, and includes a refrigerant inflow port P1 and a refrigerant outflow port P2 that is located vertically above the inflow port P1; and a lower region R1 of the refrigerant channel 100, said lower region R1 including the inflow port P1 of the refrigerant channel 100 and covering the vertically lower side of the bearing 9 when viewed in the axial direction, and an upper region R2 of the refrigerant channel 100, said upper region R2 including the outflow port P2 and covering the vertically upper side of the bearing 9 when viewed in the axial direction, wherein the vertical position of the refrigerant channel 100 does not change in the vertically downward direction along the refrigerant flow direction in at least one of the lower region R1 and the upper region R2.

Description

turbocharger

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2024-061227, filed on April 5, 2024, the contents of which are incorporated herein by reference.

[0002] The turbocharger includes a bearing housing that accommodates a bearing. As disclosed in, for example, Patent Document 1, the bearing housing has a refrigerant flow path formed therein through which a refrigerant flows.

[0003] JP 2013-011253 A

[0004] When the engine is running, a pump that pumps the coolant is driven, and the coolant circulates through the coolant flow path of the turbocharger. On the other hand, when the engine is stopped, the pump stops and the coolant stops circulating. Even in such a case, it is desirable to suppress a decrease in cooling performance due to the coolant flow path.

[0005] An object of the present disclosure is to provide a turbocharger that can suppress a decrease in cooling performance due to a refrigerant flow path when the engine is stopped.

[0006] In order to solve the above problems, the turbocharger of the present disclosure comprises: a bearing housing that accommodates a bearing; a refrigerant flow path that is formed in the bearing housing and is arranged around the bearing when viewed in the axial direction of the bearing, and that includes a refrigerant inlet and a refrigerant outlet located vertically above the inlet; a lower region of the refrigerant flow path that includes the inlet and covers the vertically below the bearing when viewed in the axial direction; and an upper region of the refrigerant flow path that includes the outlet and covers the vertically above the bearing when viewed in the axial direction, wherein in at least one of the lower region and upper region, the vertical position of the refrigerant flow path does not change vertically downward as the refrigerant proceeds in the flow direction.

[0007] In at least one of the lower region and the upper region, the vertical position of the coolant flow path may not be maintained but may change vertically upward as the coolant progresses in the flow direction.

[0008] In both the lower region and the upper region, the vertical position of the coolant flow path does not need to change vertically downward as it progresses in the direction of coolant flow.

[0009] In both the lower region and the upper region, the vertical position of the coolant flow path may not be maintained as it progresses in the direction of coolant flow, but may change vertically upward.

[0010] A branch chamber may be provided that branches off from the upper region and extends vertically downward.

[0011] A connecting channel may be provided connecting the lower region and the branch chamber.

[0012] In order to solve the above problems, the turbocharger of the present disclosure includes: a bearing housing that accommodates a bearing; and a refrigerant flow path that is formed in the bearing housing, that is arranged around the bearing when viewed in the axial direction of the bearing, that covers the vertically lower or vertically upper side of the bearing, that includes a refrigerant inlet and a refrigerant outlet located vertically above the inlet, and that does not change vertically downward as the vertical position progresses in the refrigerant flow direction.

[0013] According to the present disclosure, it is possible to suppress a decrease in cooling performance due to the refrigerant flow path when the engine is stopped.

[0014] FIG. 1 is a schematic cross-sectional view showing a turbocharger according to an embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view showing a refrigerant flow path of a bearing housing according to a comparative example. FIG. 3 is a schematic cross-sectional view showing a refrigerant flow path of a bearing housing according to an embodiment of the present disclosure. FIG. 4 is a schematic cross-sectional view showing a refrigerant flow path of a bearing housing according to a first modified example of the present disclosure. FIG. 5 is a schematic cross-sectional view showing a refrigerant flow path of a bearing housing according to a second modified example of the present disclosure. FIG. 6 is a schematic cross-sectional view showing a refrigerant flow path of a bearing housing according to a third modified example of the present disclosure. FIG. 7 is a schematic cross-sectional view showing a refrigerant flow path of a bearing housing according to a fourth modified example of the present disclosure. FIG. 8 is a schematic cross-sectional view showing a refrigerant flow path of a bearing housing according to a fifth modified example of the present disclosure. FIG. 9 is a schematic cross-sectional view showing a refrigerant flow path of a bearing housing according to a sixth modified example of the present disclosure.

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for ease of understanding and, unless otherwise specified, do not limit the present disclosure. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown.

[0016] FIG. 1 is a schematic cross-sectional view showing a turbocharger TC according to this embodiment. In the following description, the direction of arrow L shown in FIG. 1 will be referred to as the left side of the turbocharger TC. The direction of arrow R shown in FIG. 1 will be referred to as the right side of the turbocharger TC. As shown in FIG. 1, the turbocharger TC includes a turbocharger main body 1. The turbocharger main body 1 includes a bearing housing 2, a turbine housing 3, and a compressor housing 4. The turbine housing 3 is connected to the left side of the bearing housing 2 by a fastening mechanism 5. The fastening mechanism 5 is, for example, a G-coupling. The compressor housing 4 is connected to the right side of the bearing housing 2 by a fastening bolt 6. The bearing housing 2, the turbine housing 3, and the compressor housing 4 are integrated together.

[0017] The bearing housing 2 has a bearing wall 7. A bearing hole 8 is formed in the bearing wall 7. The bearing hole 8 penetrates the turbocharger TC in the left-right direction. A bearing 9 is provided in the bearing hole 8. In FIG. 1 , a semi-floating bearing is shown as an example of the bearing 9. However, the type of the bearing 9 is not limited to this example. For example, the bearing 9 may be a ball bearing or the like. A shaft 10 is rotatably supported by the bearing 9. A turbine wheel 11 is attached to the left end of the shaft 10. The turbine wheel 11 is rotatably housed in the turbine housing 3. A compressor wheel 12 is attached to the right end of the shaft 10. The compressor wheel 12 is rotatably housed in the compressor housing 4. An outlet 13 is formed in the lower part of the bearing housing 2 to discharge lubricating oil scattered from the bearing 9.

[0018] An intake port 14 is formed in the compressor housing 4. The intake port 14 opens to the right side of the turbocharger TC. The intake port 14 is connected to an air cleaner (not shown). A diffuser flow path 15 is formed by the opposing surfaces of the bearing housing 2 and the compressor housing 4. The diffuser flow path 15 is formed in an annular shape extending from the inner side toward the outer side in the radial direction of the shaft 10. The diffuser flow path 15 is connected to the intake port 14 via the compressor impeller 12 on the inner side in the radial direction of the shaft 10.

[0019] The compressor housing 4 is provided with a compressor scroll passage 16. The compressor scroll passage 16 is annular. For example, the compressor scroll passage 16 is located radially outward of the shaft 10 relative to the diffuser passage 15. The compressor scroll passage 16 communicates with an intake port of the engine (not shown). The compressor scroll passage 16 also communicates with the diffuser passage 15.

[0020] When the compressor impeller 12 rotates, air is drawn into the compressor housing 4 through the intake port 14. The drawn air is pressurized and accelerated as it flows between the blades of the compressor impeller 12. The compressed and accelerated air is then pressurized in the diffuser passage 15 and the compressor scroll passage 16. The pressurized air is then guided to the intake port of the engine.

[0021] A discharge port 17 is formed in the turbine housing 3. The discharge port 17 opens to the left side of the turbocharger TC. The discharge port 17 is connected to an exhaust gas purification device (not shown). A turbine scroll passage 18 is provided in the turbine housing 3. The turbine scroll passage 18 is annular. The turbine scroll passage 18 is located, for example, radially outward of the shaft 10 with respect to the turbine wheel 11. The turbine scroll passage 18 communicates with a gas inlet (not shown). Exhaust gas discharged from an exhaust manifold of the engine (not shown) is introduced into the gas inlet. The turbine scroll passage 18 also communicates with a space that houses the turbine wheel 11.

[0022] The exhaust gas introduced from the gas inlet into the turbine scroll passage 18 passes between the blades of the turbine wheel 11 and is introduced to the discharge port 17. The exhaust gas introduced to the discharge port 17 rotates the turbine wheel 11 during its flow process. The rotational force of the turbine wheel 11 is transmitted to the compressor wheel 12 via the shaft 10. As described above, the air is pressurized by the rotational force of the compressor wheel 12 and is introduced to the intake port of the engine.

[0023] When the engine is operating, high-temperature gas flows inside the turbocharger TC. This causes the temperature to rise at various locations in the turbocharger TC. In particular, the turbine housing 3 is prone to high temperatures. Therefore, the turbocharger TC is provided with a cooling mechanism for cooling various components. As such a cooling mechanism, a coolant flow path 100, which is a flow path through which a coolant flows, is formed in the bearing housing 2. The coolant is, for example, water. However, the coolant may be a fluid other than water. A pump (not shown) that pressurizes the coolant is provided in a flow path connected to the coolant flow path 100. When the engine is operating, the pump is driven, and the coolant circulates through the coolant flow path 100 of the turbocharger TC. This cools, for example, the turbine housing 3 and components around the turbine housing 3.

[0024] On the other hand, when the engine is stopped, the pump stops and the refrigerant stops circulating. Even in such a case, it is desirable to suppress a decrease in the cooling performance of the refrigerant flow path 100. According to this embodiment, as will be described later, by improving the structure of the refrigerant flow path 100, it is possible to suppress a decrease in the cooling performance of the refrigerant flow path 100 when the engine is stopped. Below, a comparative example will be described before this embodiment, and then this embodiment will be described.

[0025] Figure 2 is a schematic cross-sectional view showing the refrigerant flow path 100 of a bearing housing 2C according to a comparative example. Specifically, Figure 2 is a schematic cross-sectional view showing the A-A cross section of Figure 1. In other words, Figure 2 is a schematic cross-sectional view showing a cross section that passes through the refrigerant flow path 100 and is perpendicular to the axial direction of the bearing 9. Figures 3 to 9, which will be described later, are also schematic cross-sectional views showing the A-A cross section of Figure 1, similar to Figure 2.

[0026] In Figure 2, only the space in bearing housing 2C that corresponds to refrigerant flow path 100 is extracted and shown. In Figures 3 to 9 described below, only the space in bearing housings 2, 2-1, 2-2, 2-3, 2-4, 2-5, and 2-6 that corresponds to refrigerant flow path 100 is extracted and shown. In Figure 2 and Figures 3 to 9 described below, the direction of arrow U corresponds to the vertically upward direction, and the direction of arrow D corresponds to the vertically downward direction.

[0027] The coolant flow path 100 is arranged around the bearing 9 when viewed in the axial direction of the bearing 9. The coolant flow path 100 is arranged so as to cover most of the bearing 9 when viewed in the axial direction of the bearing 9.

[0028] In the bearing housing 2C according to the comparative example, the refrigerant flow path 100 includes a C-shaped flow path 101, a linear flow path 102, and a linear flow path 103. The C-shaped flow path 101 is a flow path that is C-shaped when viewed in the axial direction of the bearing 9. The linear flow paths 102 and 103 are flow paths that are linear when viewed in the axial direction of the bearing 9. In Figure 2, the boundaries between the C-shaped flow path 101, the linear flow path 102, and the linear flow path 103 are shown by dashed lines for convenience.

[0029] The C-shaped flow passage 101 is disposed, for example, substantially coaxially with the bearing 9. The C-shaped flow passage 101 extends in the circumferential direction of the bearing 9. The C-shaped flow passage 101 has, for example, a substantially vertically symmetrical shape. The C-shaped flow passage 101 has an arc shape with a central angle greater than 180°. The C-shaped flow passage 101 extends in the circumferential direction of the bearing 9 over a range of 180° or more from a vertically lower end 101a to a vertically upper end 101b.

[0030] The straight flow path 102 is connected to a vertically lower end 101a of the C-shaped flow path 101. The straight flow path 102 extends, for example, in a substantially horizontal direction. A refrigerant inlet P1 is formed at the end of the straight flow path 102 opposite the C-shaped flow path 101. A refrigerant inlet pipe 201 is connected to the inlet P1. The inlet pipe 201 extends, for example, from the inlet P1 in a substantially horizontal direction and then bends vertically downward.

[0031] The straight flow path 103 is connected to the vertically upper end 101b of the C-shaped flow path 101. The straight flow path 103 extends, for example, in a substantially horizontal direction. A refrigerant outlet P2 is formed at the end of the straight flow path 103 opposite the C-shaped flow path 101. The outlet P2 is located vertically above the inlet P1. A refrigerant outlet pipe 202 is connected to the outlet P2. The outlet pipe 202 extends, for example, from the outlet P2 in a substantially horizontal direction and then bends vertically upward.

[0032] During engine operation, the refrigerant flows along the path indicated by arrow A1 in FIG. 2 . That is, the refrigerant flow direction is indicated by arrow A1. Specifically, the refrigerant flowing through the inlet pipe 201 is sent to the straight flow path 102 through the inlet P1. The refrigerant sent to the straight flow path 102 flows approximately horizontally within the straight flow path 102 and then to the C-shaped flow path 101. The refrigerant sent to the C-shaped flow path 101 flows circumferentially around the bearing 9 within the C-shaped flow path 101 and then to the straight flow path 103. The refrigerant sent to the straight flow path 103 flows approximately horizontally within the straight flow path 103 and then to the outlet pipe 202 through the outlet P2. The inlet pipe 201, the refrigerant flow path 100, and the outlet pipe 202, together with a flow path not shown, form a closed loop. Therefore, during engine operation, the refrigerant circulates within this closed loop flow path.

[0033] On the other hand, when the engine is stopped, the pump stops and the refrigerant stops circulating. As a result, the refrigerant hardly flows within the refrigerant flow path 100. Therefore, the refrigerant within the refrigerant flow path 100 is heated by heat from the turbine housing 3 and the like, and some of the refrigerant may evaporate within the refrigerant flow path 100. In this case, in the bearing housing 2C according to the comparative example, vapor V1 tends to accumulate within the refrigerant flow path 100, as shown in FIG. 2 .

[0034] Specifically, vapor V1 generated in refrigerant flow path 100 tends to accumulate near downward gradient regions DR in lower region R1 and upper region R2 of refrigerant flow path 100. Lower region R1 is a region of refrigerant flow path 100 that includes inlet P1 and covers the vertically lower side of bearing 9 when viewed in the axial direction of bearing 9. Upper region R2 is a region of refrigerant flow path 100 that includes outlet P2 and covers the vertically upper side of bearing 9 when viewed in the axial direction of bearing 9. Downward gradient region DR is a region where the vertical position of refrigerant flow path 100 changes vertically downward as the refrigerant flows in the direction of flow.

[0035] In the bearing housing 2C, the lower half of the C-shaped flow path 101 and the linear flow path 102 are included in the lower region R1. In this lower region R1, in the region from the vertically lower end 101a of the C-shaped flow path 101 to the bottom, the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows. In other words, the region from the vertically lower end 101a of the C-shaped flow path 101 to the bottom corresponds to the downward gradient region DR in the lower region R1. For example, if vapor V1 is generated in or near the downward gradient region DR in the lower region R1, the vapor V1 will rise due to buoyancy and tend to accumulate near the vertically lower end 101a of the C-shaped flow path 101.

[0036] In the bearing housing 2C, the upper half of the C-shaped flow path 101 and the linear flow path 103 are included in the upper region R2. In this upper region R2, in the region from the top of the C-shaped flow path 101 to the vertically upper end 101b, the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows in the direction of flow. In other words, the region from the top of the C-shaped flow path 101 to the vertically upper end 101b corresponds to the downward gradient region DR in the upper region R2. For example, if vapor V1 is generated in or near the downward gradient region DR in the upper region R2, the vapor V1 will rise due to buoyancy and tend to accumulate near the top of the C-shaped flow path 101.

[0037] As described above, in the bearing housing 2C according to the comparative example, vapor V1 is likely to accumulate in the refrigerant flow path 100 when the engine is stopped. When vapor V1 accumulates in the refrigerant flow path 100, the heat transfer coefficient in the refrigerant flow path 100 decreases, and the cooling performance of the refrigerant flow path 100 decreases. Hereinafter, with reference to FIG. 3 , a description will be given of a feature of this embodiment for suppressing the decrease in cooling performance of the refrigerant flow path 100 when the engine is stopped.

[0038] 3 is a schematic cross-sectional view showing the refrigerant flow path 100 of the bearing housing 2 according to this embodiment. In this embodiment as well, the refrigerant flow path 100 is arranged around the bearing 9 when viewed in the axial direction of the bearing 9. The refrigerant flow path 100 is arranged so as to cover most of the bearing 9 when viewed in the axial direction of the bearing 9.

[0039] In the bearing housing 2 according to this embodiment, the refrigerant flow path 100 includes a semicircular flow path 104, a linear flow path 105, and a linear flow path 106. The semicircular flow path 104 is a flow path that is semicircular when viewed in the axial direction of the bearing 9. The linear flow paths 105 and 106 are flow paths that are linear when viewed in the axial direction of the bearing 9. In Figure 3, the boundaries between the semicircular flow path 104, the linear flow path 105, and the linear flow path 106 are indicated by dashed lines for convenience.

[0040] The semicircular flow path 104 is disposed, for example, substantially coaxially with the bearing 9. The semicircular flow path 104 extends in the circumferential direction of the bearing 9. The semicircular flow path 104 has, for example, a shape that is substantially symmetrical from top to bottom. The semicircular flow path 104 has an arc shape with a central angle of 180°. The semicircular flow path 104 extends over a range of 180° in the circumferential direction of the bearing 9, from an end 104a located directly below the center of the semicircular flow path 104 to an end 104b located directly above the center of the semicircular flow path 104. The center of the semicircular flow path 104 refers to the center of the arc that corresponds to the center line of the semicircular flow path 104.

[0041] The straight flow path 105 is connected to a vertically lower end 104a of the semicircular flow path 104. The straight flow path 105 extends, for example, in a substantially horizontal direction. A refrigerant inlet P1 is formed at the end of the straight flow path 105 opposite the semicircular flow path 104. A refrigerant inlet pipe 201 is connected to the inlet P1. The inlet pipe 201 extends, for example, from the inlet P1 in a substantially horizontal direction and then bends vertically downward.

[0042] The straight flow path 106 is connected to the vertically upper end 104b of the semicircular flow path 104. The straight flow path 106 extends, for example, in a substantially horizontal direction. A refrigerant outlet P2 is formed at the end of the straight flow path 106 opposite the semicircular flow path 104. The outlet P2 is located vertically above the inlet P1. A refrigerant outlet pipe 202 is connected to the outlet P2. The outlet pipe 202 extends, for example, from the outlet P2 in a substantially horizontal direction and then bends vertically upward.

[0043] The flow direction of the refrigerant during engine operation is indicated by arrow A1 in Figure 3. Specifically, the refrigerant flowing through the inlet pipe 201 is sent to the straight flow path 105 through the inlet P1. The refrigerant sent to the straight flow path 105 flows substantially horizontally within the straight flow path 105 and is then sent to the semicircular flow path 104. The refrigerant sent to the semicircular flow path 104 flows in the circumferential direction of the bearing 9 within the semicircular flow path 104 and is then sent to the straight flow path 106. The refrigerant sent to the straight flow path 106 flows substantially horizontally within the straight flow path 106 and is then sent to the outlet pipe 202 through the outlet P2.

[0044] As described above, in the bearing housing 2C of the comparative example, when the engine is stopped, vapor V1 generated in the refrigerant flow path 100 tends to accumulate near the downward gradient region DR in the lower region R1 and upper region R2 of the refrigerant flow path 100. On the other hand, in the bearing housing 2 of the present embodiment, in the lower region R1 and upper region R2 of the refrigerant flow path 100, there is no downward gradient region DR where the vertical position of the refrigerant flow path 100 changes vertically downward as it progresses in the refrigerant flow direction.

[0045] In the bearing housing 2, the lower region R1 includes the lower half of the semicircular flow path 104 and the linear flow path 105. In the linear flow path 105 of the lower region R1, the vertical position of the refrigerant flow path 100 is maintained as the refrigerant flows in the direction of flow. In the semicircular flow path 104 of the lower region R1, the vertical position of the refrigerant flow path 100 changes vertically upward as the refrigerant flows in the direction of flow. Thus, in the lower region R1, the vertical position of the refrigerant flow path 100 is maintained or changes vertically upward as the refrigerant flows in the direction of flow. Therefore, in the lower region R1, the vertical position of the refrigerant flow path 100 does not change vertically downward as the refrigerant flows in the direction of flow. In other words, there is no point in the lower region R1 where the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows in the direction of flow. Therefore, when steam V1 is generated in the lower region R1, the steam V1 rises due to buoyancy and is sent to the upper region R2, making it less likely to accumulate in the lower region R1.

[0046] Furthermore, in the bearing housing 2, the upper region R2 includes the upper half of the semicircular flow path 104 and the linear flow path 106. In the semicircular flow path 104 of the upper region R2, the vertical position of the refrigerant flow path 100 changes vertically upward as the refrigerant flows in the direction of flow. In the linear flow path 106 of the upper region R2, the vertical position of the refrigerant flow path 100 is maintained as the refrigerant flows in the direction of flow. Thus, in the upper region R2, the vertical position of the refrigerant flow path 100 is maintained or changes vertically upward as the refrigerant flows in the direction of flow. Therefore, in the upper region R2, the vertical position of the refrigerant flow path 100 does not change vertically downward as the refrigerant flows in the direction of flow. In other words, there is no point in the upper region R2 where the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows in the direction of flow. Therefore, when steam V1 is generated in the upper region R2, the steam V1 rises due to buoyancy and is sent to the outflow pipe 202, making it less likely to accumulate in the upper region R2.

[0047] As described above, in the bearing housing 2 according to this embodiment, the vertical position of the refrigerant flow path 100 does not change vertically downward as the refrigerant flows in both the lower region R1 and the upper region R2. Therefore, the downward gradient region DR does not exist in both the lower region R1 and the upper region R2. This prevents vapor V1 from accumulating in the refrigerant flow path 100 when the engine is stopped, thereby preventing a decrease in the cooling performance of the refrigerant flow path 100 when the engine is stopped.

[0048] As described below, in one of the lower region R1 and the upper region R2, the vertical position of the refrigerant flow path 100 does not change vertically downward as the refrigerant flows. However, in the other of the lower region R1 and the upper region R2, there may be a portion where the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows. Even in this case, as described below, the deterioration of the cooling performance of the refrigerant flow path 100 when the engine is stopped can be suppressed. However, from the viewpoint of effectively suppressing the deterioration of the cooling performance of the refrigerant flow path 100 when the engine is stopped, it is preferable that the vertical position of the refrigerant flow path 100 does not change vertically downward as the refrigerant flows in both the lower region R1 and the upper region R2.

[0049] As shown in Fig. 3, the bearing housing 2 includes a branch chamber BR that branches off from the upper region R2 and extends vertically downward. In the example of Fig. 3, the branch chamber BR extends vertically downward from the upstream portion of the linear flow path 106. The branch chamber BR is disposed, for example, substantially coaxial with the bearing 9. The branch chamber BR extends in the circumferential direction of the bearing 9. In the example of Fig. 3, the vertical position of the lower end of the branch chamber BR is vertically above the central axis of the bearing 9. However, the vertical position of the lower end of the branch chamber BR may also coincide with the central axis of the bearing 9 or may be vertically below the central axis of the bearing 9.

[0050] When the branch chamber BR is provided in the bearing housing 2, a larger amount of refrigerant is present in the bearing housing 2 than when the branch chamber BR is not provided in the bearing housing 2. For example, when the branch chamber BR is provided in the bearing housing 2, a larger amount of refrigerant is present near the bearing 9 than when the branch chamber BR is not provided in the bearing housing 2. This improves the cooling performance of the refrigerant flow path 100 when the engine is running and when it is stopped. In the bearing housing 2, the path of the refrigerant flow path 100 is changed from the example in FIG. 2 so that the downward slope region DR is not present. The volume of the branch chamber BR can compensate for the reduction in volume of the refrigerant flow path 100. However, the branch chamber BR does not have to be provided in the bearing housing 2.

[0051] Hereinafter, first to sixth modified examples will be described in order as modifications in which various changes have been made to the above-described bearing housing 2.

[0052] 4 is a schematic cross-sectional view showing the refrigerant flow path 100 of a bearing housing 2-1 according to the first modified example. The bearing housing 2-1 according to the first modified example differs from the bearing housing 2 described above in that the upper region R2 has a portion where the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows in the direction of flow.

[0053] In the bearing housing 2-1 according to the first modification, the refrigerant flow path 100 includes an arc-shaped flow path 107, a linear flow path 108, and a linear flow path 109. The arc-shaped flow path 107 is a flow path that is arc-shaped when viewed in the axial direction of the bearing 9. The linear flow paths 108 and 109 are flow paths that are linear when viewed in the axial direction of the bearing 9. In Figure 4, the boundaries between the arc-shaped flow path 107, the linear flow path 108, and the linear flow path 109 are shown by dashed lines for the sake of convenience.

[0054] The arc-shaped flow path 107 is disposed, for example, substantially coaxially with the bearing 9. The arc-shaped flow path 107 extends in the circumferential direction of the bearing 9. The arc-shaped flow path 107 has an asymmetric shape in the up-down direction. The arc-shaped flow path 107 has an arc shape with a central angle greater than 180°. The arc-shaped flow path 107 extends over a range of 180° or more in the circumferential direction of the bearing 9, from an end 107a located directly below the center of the arc-shaped flow path 107 to an end 107b located vertically above the end 107a. The center of the arc-shaped flow path 107 refers to the center of the arc corresponding to the center line of the arc-shaped flow path 107.

[0055] The straight flow path 108 is connected to an end 107a on the vertically lower side of the arc-shaped flow path 107. The straight flow path 108 extends, for example, in a substantially horizontal direction. A refrigerant inlet P1 is formed at the end of the straight flow path 108 opposite the arc-shaped flow path 107. A refrigerant inlet pipe 201 is connected to the inlet P1. The inlet pipe 201 extends, for example, from the inlet P1 in a substantially horizontal direction and then bends vertically downward.

[0056] The straight flow path 109 is connected to the vertically upper end 107b of the arc-shaped flow path 107. The straight flow path 109 extends, for example, in a substantially horizontal direction. A refrigerant outlet P2 is formed at the end of the straight flow path 109 opposite the arc-shaped flow path 107. The outlet P2 is located vertically above the inlet P1. A refrigerant outlet pipe 202 is connected to the outlet P2. The outlet pipe 202 extends, for example, from the outlet P2 in a substantially horizontal direction and then bends vertically upward.

[0057] The flow direction of the refrigerant during engine operation is indicated by arrow A1 in Figure 4. Specifically, the refrigerant flowing through inlet pipe 201 is sent to straight flow path 108 through inlet P1. The refrigerant sent to straight flow path 108 flows substantially horizontally within straight flow path 108 and then is sent to arc-shaped flow path 107. The refrigerant sent to arc-shaped flow path 107 flows in the circumferential direction of bearing 9 within arc-shaped flow path 107 and then is sent to straight flow path 109. The refrigerant sent to straight flow path 109 flows substantially horizontally within straight flow path 109 and then is sent to outlet pipe 202 through outlet P2.

[0058] In the bearing housing 2-1, the lower region R1 includes the portion of the arc-shaped flow path 107 below the center of the arc-shaped flow path 107 and the linear flow path 108. In the linear flow path 108 of the lower region R1, the vertical position of the refrigerant flow path 100 is maintained as the refrigerant progresses in the flow direction. In the arc-shaped flow path 107 of the lower region R1, the vertical position of the refrigerant flow path 100 changes vertically upward as the refrigerant progresses in the flow direction. Thus, in the lower region R1, the vertical position of the refrigerant flow path 100 is maintained or changes vertically upward as the refrigerant progresses in the flow direction. Therefore, in the lower region R1, the vertical position of the refrigerant flow path 100 does not change vertically downward as the refrigerant progresses in the flow direction. In other words, there is no point in the lower region R1 where the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant progresses in the flow direction. Therefore, when steam V1 is generated in the lower region R1, the steam V1 rises due to buoyancy and is sent to the upper region R2, making it less likely to accumulate in the lower region R1.

[0059] In the bearing housing 2-1, the upper region R2 includes the portion of the arc-shaped flow path 107 above the center of the arc-shaped flow path 107 and the linear flow path 109. In this upper region R2, in the region from the top of the arc-shaped flow path 107 to the vertically upper end 107b, the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows in the direction of flow.

[0060] As described above, in the bearing housing 2-1 according to the first modification, although there are portions in the upper region R2 where the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows, in the lower region R1, the vertical position of the refrigerant flow path 100 does not change vertically downward as the refrigerant flows. Therefore, the downward gradient region DR does not exist in the lower region R1. This prevents vapor V1 from accumulating in at least the lower region R1 of the refrigerant flow path 100 when the engine is stopped, thereby preventing a decrease in the cooling performance of the refrigerant flow path 100 when the engine is stopped.

[0061] As shown in FIG. 4 , the bearing housing 2-1, like the bearing housing 2 described above, includes a branch chamber BR that branches off from the upper region R2 and extends vertically downward. In the example of FIG. 4 , the branch chamber BR extends vertically downward from the connection between the arc-shaped flow path 107 and the linear flow path 109. As described above, the vertical position of the lower end of the branch chamber BR is not limited to the example of FIG. 4 . In the example of FIG. 4 , providing the branch chamber BR in the bearing housing 2-1 can improve the cooling performance of the refrigerant flow path 100 both when the engine is running and when it is stopped, as described above. However, the branch chamber BR does not necessarily have to be provided in the bearing housing 2-1.

[0062] 5 is a schematic cross-sectional view showing the refrigerant flow path 100 of a bearing housing 2-2 according to a second modified example. The bearing housing 2-2 according to the second modified example differs from the bearing housing 2 described above in that the lower region R1 has a portion where the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows in the direction of flow.

[0063] In the bearing housing 2-2 according to the second modification, the refrigerant flow path 100 includes an arc-shaped flow path 110, a linear flow path 111, and a linear flow path 112. The arc-shaped flow path 110 is a flow path that is arc-shaped when viewed in the axial direction of the bearing 9. The linear flow paths 111 and 112 are flow paths that are linear when viewed in the axial direction of the bearing 9. In Figure 5, the boundaries between the arc-shaped flow path 110, the linear flow path 111, and the linear flow path 112 are shown by dashed lines for convenience.

[0064] The arc-shaped flow path 110 is disposed, for example, substantially coaxially with the bearing 9. The arc-shaped flow path 110 extends in the circumferential direction of the bearing 9. The arc-shaped flow path 110 has an asymmetric shape in the up-down direction. The arc-shaped flow path 110 has an arc shape with a central angle greater than 180°. The arc-shaped flow path 110 extends over a range of 180° or more in the circumferential direction of the bearing 9, from an end 110b located directly above the center of the arc-shaped flow path 110 to an end 110a located vertically below end 110b. The center of the arc-shaped flow path 110 refers to the center of the arc corresponding to the center line of the arc-shaped flow path 110.

[0065] The straight flow path 111 is connected to a vertically lower end 110a of the arc-shaped flow path 110. The straight flow path 111 extends, for example, in a substantially horizontal direction. A refrigerant inlet P1 is formed at the end of the straight flow path 111 opposite the arc-shaped flow path 110. A refrigerant inlet pipe 201 is connected to the inlet P1. The inlet pipe 201 extends, for example, from the inlet P1 in a substantially horizontal direction and then bends vertically downward.

[0066] The straight flow path 112 is connected to the vertically upper end 110b of the arc-shaped flow path 110. The straight flow path 112 extends, for example, in a substantially horizontal direction. A refrigerant outlet P2 is formed at the end of the straight flow path 112 opposite the arc-shaped flow path 110. The outlet P2 is located vertically above the inlet P1. A refrigerant outlet pipe 202 is connected to the outlet P2. The outlet pipe 202 extends, for example, from the outlet P2 in a substantially horizontal direction and then bends vertically upward.

[0067] The flow direction of the refrigerant during engine operation is indicated by arrow A1 in Figure 5. Specifically, the refrigerant flowing through the inlet pipe 201 is sent to the straight flow path 111 through the inlet P1. The refrigerant sent to the straight flow path 111 flows substantially horizontally within the straight flow path 111 and is then sent to the arc-shaped flow path 110. The refrigerant sent to the arc-shaped flow path 110 flows in the circumferential direction of the bearing 9 within the arc-shaped flow path 110 and is then sent to the straight flow path 112. The refrigerant sent to the straight flow path 112 flows substantially horizontally within the straight flow path 112 and is then sent to the outlet pipe 202 through the outlet P2.

[0068] In the bearing housing 2-2, the lower region R1 includes the portion of the arc-shaped flow path 110 below the center of the arc-shaped flow path 110 and the linear flow path 111. In this lower region R1, in the region from the vertically lower end 110a of the arc-shaped flow path 110 to the bottom, the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows in the direction of flow.

[0069] In the bearing housing 2-2, the upper region R2 includes the portion of the arc-shaped flow path 110 above the center of the arc-shaped flow path 110 and the linear flow path 112. In the arc-shaped flow path 110 in the upper region R2, the vertical position of the refrigerant flow path 100 changes vertically upward as the refrigerant flows in the flow direction. In the linear flow path 112 in the upper region R2, the vertical position of the refrigerant flow path 100 is maintained as the refrigerant flows in the flow direction. Thus, in the upper region R2, the vertical position of the refrigerant flow path 100 is maintained or changes vertically upward as the refrigerant flows in the flow direction. Therefore, in the upper region R2, the vertical position of the refrigerant flow path 100 does not change vertically downward as the refrigerant flows in the flow direction. In other words, there is no point in the upper region R2 where the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows in the flow direction. Therefore, when steam V1 is generated in the upper region R2, the steam V1 rises due to buoyancy and is sent to the outflow pipe 202, making it less likely to accumulate in the upper region R2.

[0070] As described above, in the bearing housing 2-2 according to the second modification, although there are portions in the lower region R1 where the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows, in the upper region R2, the vertical position of the refrigerant flow path 100 does not change vertically downward as the refrigerant flows. Therefore, the downward gradient region DR does not exist in the upper region R2. This prevents vapor V1 from accumulating in at least the upper region R2 of the refrigerant flow path 100 when the engine is stopped, thereby preventing a decrease in the cooling performance of the refrigerant flow path 100 when the engine is stopped.

[0071] As shown in FIG. 5 , the bearing housing 2-2, like the bearing housing 2 described above, includes a branch chamber BR that branches off from the upper region R2 and extends vertically downward. In the example of FIG. 5 , the branch chamber BR extends vertically downward from the upstream portion of the linear flow path 112. As described above, the vertical position of the lower end of the branch chamber BR is not limited to the example of FIG. 5 . In the example of FIG. 5 , providing the branch chamber BR in the bearing housing 2-2 can improve the cooling performance of the refrigerant flow path 100 both when the engine is running and when it is stopped, as described above. However, the branch chamber BR does not necessarily have to be provided in the bearing housing 2-2.

[0072] 6 is a schematic cross-sectional view showing the refrigerant flow path 100 of a bearing housing 2-3 according to a third modified example. The bearing housing 2-3 according to the third modified example differs from the bearing housing 2 described above in that the lower region R1 and the branch chamber BR are connected by a connecting flow path CP.

[0073] The bearing housing 2-3 according to the third modification includes a connection flow passage CP. The connection flow passage CP connects the lower region R1 and the branch chamber BR. In the example shown in FIG. 6, the connection flow passage CP branches vertically upward from the straight flow passage 105. The lower end of the branch chamber BR is connected to the end of the connection flow passage CP opposite the straight flow passage 105. In FIG. 6, the boundary between the straight flow passage 105 and the connection flow passage CP, and the boundary between the connection flow passage CP and the branch chamber BR are shown by dashed lines for convenience.

[0074] As described above, the bearing housing 2-3 according to the third modified example includes the connection passage CP that connects the lower region R1 and the branch chamber BR. As a result, during engine operation, as shown by arrow A2 in FIG. 6 , a portion of the refrigerant sent from the inlet pipe 201 to the straight passage 105 passes through the connection passage CP and the branch chamber BR and is sent to the straight passage 106. Therefore, in addition to the refrigerant flow in the refrigerant passage 100 shown by arrow A1, cooling can be achieved by the refrigerant flow in the connection passage CP and the branch chamber BR shown by arrow A2. This further improves the cooling performance of the refrigerant.

[0075] As shown in Figure 6, in the bearing housing 2-3, when viewed in the axial direction of the bearing 9, one horizontal side of the bearing 9 (the left side in Figure 6) is covered by the semicircular flow path 104, and the other horizontal side of the bearing 9 (the right side in Figure 6) is covered by the connection flow path CP and the branch chamber BR. The connection flow path CP and the branch chamber BR can also be considered part of the refrigerant flow path 100. In other words, in the bearing housing 2-3, when viewed in the axial direction of the bearing 9, the entire circumference of the bearing 9 is covered by the refrigerant flow path 100. In this way, in the bearing housing according to the present disclosure, the refrigerant flow path 100 may have a branched and merged portion, or may cover the entire circumference of the bearing 9 when viewed in the axial direction of the bearing 9.

[0076] In the example of Fig. 6 , the inlet P1 and the outlet P2 are arranged on the same side (the right side in Fig. 6 ) of the bearing 9 in the horizontal direction. However, the inlet P1 and the outlet P2 may be arranged on different sides of the bearing 9 in the horizontal direction. For example, in the example of Fig. 6 , the arrangement of the outlet P2 may be changed so that the outlet P2 faces leftward in Fig. 6 from the top of the semicircular flow channel 104. For example, in the example of Fig. 6 , the arrangement of the inlet P1 may be changed so that the inlet P1 faces leftward in Fig. 6 from the bottom of the semicircular flow channel 104.

[0077] A connecting flow passage CP may be added to the above-described bearing housing 2, bearing housing 2-1, bearing housing 2-2, and a bearing housing 2-4 to be described later.

[0078] 7 is a schematic cross-sectional view showing the refrigerant flow path 100 of a bearing housing 2-4 according to a fourth modified example. The bearing housing 2-4 according to the fourth modified example differs from the bearing housing 2 described above in that the straight flow paths 105 and 106 are replaced with straight flow paths 113 and 114, respectively.

[0079] In the bearing housing 2-4 according to the fourth modification, the refrigerant flow path 100 includes a semicircular flow path 104, a linear flow path 113, and a linear flow path 114. The linear flow paths 113 and 114 are linear flow paths when viewed in the axial direction of the bearing 9. In Fig. 7, the boundaries between the semicircular flow path 104, the linear flow path 113, and the linear flow path 114 are indicated by dashed lines for the sake of convenience.

[0080] The straight flow path 113 is connected to the vertically lower end 104a of the semicircular flow path 104. The vertical position of the straight flow path 113 changes vertically downward as it moves away from the end 104a. A refrigerant inlet P1 is formed at the end of the straight flow path 113 opposite the semicircular flow path 104. A refrigerant inlet pipe 201 is connected to the inlet P1. The inlet pipe 201 extends, for example, from the inlet P1 in a substantially horizontal direction and then bends vertically downward.

[0081] The straight flow path 114 is connected to the vertically upper end 104b of the semicircular flow path 104. The vertical position of the straight flow path 114 changes vertically upward as it moves away from the end 104a. A refrigerant outlet P2 is formed at the end of the straight flow path 114 opposite the semicircular flow path 104. The outlet P2 is located vertically above the inlet P1. A refrigerant outlet pipe 202 is connected to the outlet P2. The outlet pipe 202 extends, for example, from the outlet P2 in a substantially horizontal direction and then bends vertically upward.

[0082] The flow direction of the refrigerant during engine operation is indicated by arrow A1 in Figure 7. Specifically, the refrigerant flowing through the inlet pipe 201 is sent to the straight flow path 113 through the inlet P1. The refrigerant sent to the straight flow path 113 flows within the straight flow path 113 in a direction inclined vertically upward with respect to the horizontal direction, and then is sent to the semicircular flow path 104. The refrigerant sent to the semicircular flow path 104 flows within the semicircular flow path 104 in the circumferential direction of the bearing 9, and then is sent to the straight flow path 114. The refrigerant sent to the straight flow path 114 flows within the straight flow path 114 in a direction inclined vertically upward with respect to the horizontal direction, and then is sent to the outlet pipe 202 through the outlet P2.

[0083] In the bearing housing 2-4, the lower region R1 includes the lower half of the semicircular flow path 104 and the linear flow path 113. In the lower region R1, the vertical position of the refrigerant flow path 100 is not maintained as the refrigerant advances in the flow direction, but changes vertically upward, not only in the semicircular flow path 104 but also in the linear flow path 113. Thus, in the lower region R1, the vertical position of the refrigerant flow path 100 changes vertically upward as the refrigerant advances in the flow direction throughout the entire refrigerant flow direction. In other words, in the lower region R1, there is no location where the vertical position of the refrigerant flow path 100 is maintained as the refrigerant advances in the flow direction, nor is there a location where the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant advances in the flow direction. Therefore, when vapor V1 is generated in the lower region R1, the vapor V1 is more likely to be sent to the upper region R2 and is less likely to accumulate in the lower region R1.

[0084] Furthermore, in the bearing housing 2-4, the upper half of the semicircular flow path 104 and the linear flow path 114 are included in the upper region R2. In the upper region R2, not only in the semicircular flow path 104 but also in the linear flow path 114, the vertical position of the refrigerant flow path 100 is not maintained as the refrigerant advances in the flow direction, but changes vertically upward. Thus, in the upper region R2, the vertical position of the refrigerant flow path 100 changes vertically upward as the refrigerant advances in the flow direction throughout the entire refrigerant flow direction. In other words, in the upper region R2, there is no location where the vertical position of the refrigerant flow path 100 is maintained as the refrigerant advances in the flow direction, nor is there a location where the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant advances in the flow direction. Therefore, when vapor V1 is generated in the upper region R2, the vapor V1 is more likely to be sent to the outflow pipe 202 and is less likely to accumulate in the upper region R2.

[0085] As described above, in the bearing housing 2-4 according to the fourth modification, in both the lower region R1 and the upper region R2, the vertical position of the refrigerant flow path 100 is not maintained as the refrigerant advances in the flow direction, but instead moves vertically upward. Therefore, in both the lower region R1 and the upper region R2, there is no location where the vertical position of the refrigerant flow path 100 is maintained as the refrigerant advances in the flow direction, nor is there a location where the vertical position of the refrigerant flow path 100 moves vertically downward as the refrigerant advances in the flow direction. This effectively prevents vapor V1 from accumulating in the refrigerant flow path 100 when the engine is stopped, thereby effectively preventing a decrease in the cooling performance of the refrigerant flow path 100 when the engine is stopped.

[0086] However, in only one of the lower region R1 and the upper region R2, the vertical position of the refrigerant flow path 100 may not be maintained but may change vertically upward as the refrigerant progresses in the flow direction. For example, in the above-described bearing housing 2, the linear flow path 105 may be replaced with the linear flow path 113, but the linear flow path 106 may not be replaced with the linear flow path 114. For example, in the above-described bearing housing 2, the linear flow path 106 may be replaced with the linear flow path 114, but the linear flow path 105 may not be replaced with the linear flow path 113. For example, in the above-described bearing housing 2-1, the linear flow path 108 may be replaced with the linear flow path 113. For example, in the above-described bearing housing 2-2, the linear flow path 112 may be replaced with the linear flow path 114.

[0087] As shown in FIG. 7 , the bearing housing 2-4, like the bearing housing 2 described above, includes a branch chamber BR that branches off from the upper region R2 and extends vertically downward. In the example of FIG. 7 , the branch chamber BR extends vertically downward from the upstream portion of the linear flow path 114. As described above, the vertical position of the lower end of the branch chamber BR is not limited to the example of FIG. 7 . In the example of FIG. 7 , providing the branch chamber BR in the bearing housing 2-4 can improve the cooling performance of the refrigerant flow path 100 both when the engine is running and when it is stopped, as described above. However, the branch chamber BR does not necessarily have to be provided in the bearing housing 2-4.

[0088] 8 is a schematic cross-sectional view showing the refrigerant flow path 100 of a bearing housing 2-5 according to a fifth modified example. The bearing housing 2-5 according to the fifth modified example differs from the bearing housing 2 described above in that the refrigerant flow path 100 has an upper region R2 but does not have a lower region R1.

[0089] In the bearing housing 2-5 according to the fifth modification, the refrigerant flow path 100 includes a quadrant flow path 115 and a straight flow path 116. The quadrant flow path 115 is a flow path that is quadrant-shaped when viewed in the axial direction of the bearing 9. The straight flow path 116 is a flow path that is straight when viewed in the axial direction of the bearing 9. In Figure 8, the boundary between the quadrant flow path 115 and the straight flow path 116 is shown by a dashed line for convenience.

[0090] The quadrant flow passage 115 is disposed, for example, substantially coaxially with the bearing 9. The quadrant flow passage 115 extends in the circumferential direction of the bearing 9. The quadrant flow passage 115 has an asymmetrical shape in the up-down direction. The quadrant flow passage 115 has an arc shape with a central angle of 90°. The quadrant flow passage 115 extends over a range of 90° in the circumferential direction of the bearing 9, from an end 115b located directly above the center of the quadrant flow passage 115 to an end 115a located vertically below the end 115b. The center of the quadrant flow passage 115 refers to the center of the arc corresponding to the center line of the quadrant flow passage 115.

[0091] A refrigerant inlet P1 is formed at the vertically lower end 115a of the quadrant-shaped flow path 115. For example, the inlet P1 is formed at a portion of the end 115a that is radially outward of the bearing 9. A refrigerant inlet pipe 201 is connected to the inlet P1. For example, the inlet pipe 201 extends from the inlet P1 in a substantially horizontal direction and then bends vertically downward.

[0092] The straight flow path 116 is connected to the vertically upper end 115b of the quadrant flow path 115. The straight flow path 116 extends, for example, in a substantially horizontal direction. A refrigerant outlet P2 is formed at the end of the straight flow path 116 opposite the quadrant flow path 115. The outlet P2 is located vertically above the inlet P1. A refrigerant outlet pipe 202 is connected to the outlet P2. The outlet pipe 202 extends, for example, from the outlet P2 in a substantially horizontal direction and then bends vertically upward.

[0093] The direction of refrigerant flow during engine operation is indicated by arrow A1 in Figure 8. Specifically, the refrigerant flowing through the inlet pipe 201 passes through the inlet port P1 and is sent to the quadrant channel 115. The refrigerant sent to the quadrant channel 115 flows circumferentially around the bearing 9 within the quadrant channel 115 and is then sent to the straight channel 116. The refrigerant sent to the straight channel 116 flows approximately horizontally within the straight channel 116 and is then sent to the outlet pipe 202 through the outlet port P2.

[0094] In the bearing housing 2-5, the refrigerant flow path 100 has an upper region R2 including a quadrant-shaped flow path 115 and a linear flow path 116, but does not have a lower region R1. As such, when viewed in the axial direction of the bearing 9, the refrigerant flow path 100 is disposed around the bearing 9, covering the vertically upper side of the bearing 9 but not the vertically lower side of the bearing 9. In the quadrant-shaped flow path 115, the vertical position of the refrigerant flow path 100 changes vertically upward as it progresses in the refrigerant flow direction. In the linear flow path 116, the vertical position of the refrigerant flow path 100 is maintained as it progresses in the refrigerant flow direction.

[0095] Thus, in the bearing housing 2-5, the vertical position of the refrigerant flow path 100 is maintained or changes vertically upward as the refrigerant flows in the direction of flow. Therefore, the vertical position of the refrigerant flow path 100 does not change vertically downward as the refrigerant flows in the direction of flow. In other words, there is no point where the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows in the direction of flow. Therefore, when vapor V1 is generated in the refrigerant flow path 100, the vapor V1 rises due to buoyancy and is sent to the outflow pipe 202, making it less likely to accumulate in the refrigerant flow path 100.

[0096] As described above, in the bearing housing 2-5 according to the fifth modification, the refrigerant flow path 100 is formed in the bearing housing 2 and is disposed around the bearing 9 when viewed in the axial direction of the bearing 9, covering the vertically upper side of the bearing 9. The vertical position of the refrigerant flow path 100 does not change vertically downward as the refrigerant advances in the flow direction. Therefore, the downward gradient region DR does not exist in the refrigerant flow path 100. This prevents vapor V1 from accumulating in the refrigerant flow path 100 when the engine is stopped, thereby preventing a decrease in the cooling performance of the refrigerant flow path 100 when the engine is stopped.

[0097] 8 , the straight flow path 116 may be modified so that the vertical position of the straight flow path 116 moves vertically upward as it moves away from the end 115b. In this case, the vertical position of the refrigerant flow path 100 is not maintained throughout the entire refrigerant flow path 100, but moves vertically upward as the refrigerant advances in the flow direction. This effectively prevents vapor V1 from accumulating in the refrigerant flow path 100 when the engine is stopped, thereby effectively preventing a decrease in the cooling performance of the refrigerant flow path 100 when the engine is stopped.

[0098] 8, a branch chamber BR may be added that branches off from the upper region R2 and extends vertically downward. In this case, the branch chamber BR may extend vertically downward from, for example, an upstream portion of the linear flow path 116.

[0099] 9 is a schematic cross-sectional view showing the refrigerant flow path 100 of a bearing housing 2-6 according to a sixth modified example. The bearing housing 2-6 according to the sixth modified example differs from the bearing housing 2 described above in that the refrigerant flow path 100 has a lower region R1 but does not have an upper region R2.

[0100] In the bearing housing 2-6 according to the sixth modification, the refrigerant flow path 100 includes a quadrant flow path 117 and a straight flow path 118. The quadrant flow path 117 is a flow path that is quadrant-shaped when viewed in the axial direction of the bearing 9. The straight flow path 118 is a flow path that is straight when viewed in the axial direction of the bearing 9. In Fig. 9, the boundary between the quadrant flow path 117 and the straight flow path 118 is indicated by a dashed line for convenience.

[0101] The quadrant flow passage 117 is disposed, for example, substantially coaxially with the bearing 9. The quadrant flow passage 117 extends in the circumferential direction of the bearing 9. The quadrant flow passage 117 has an asymmetrical shape in the up-down direction. The quadrant flow passage 117 has an arc shape with a central angle of 90°. The quadrant flow passage 117 extends over a range of 90° in the circumferential direction of the bearing 9, from an end 117a located directly below the center of the quadrant flow passage 117 to an end 117b located vertically above the end 117a. The center of the quadrant flow passage 117 refers to the center of the arc corresponding to the center line of the quadrant flow passage 117.

[0102] The straight flow path 118 is connected to a vertically lower end 117a of the quadrant flow path 117. The straight flow path 118 extends, for example, in a substantially horizontal direction. An inlet P1 is formed at the end of the straight flow path 118 opposite the quadrant flow path 117. A refrigerant inlet pipe 201 is connected to the inlet P1. The inlet pipe 201 extends, for example, from the inlet P1 in a substantially horizontal direction and then bends vertically downward.

[0103] A refrigerant outlet P2 is formed at the vertically upper end 117b of the quadrant-shaped flow path 117. For example, the outlet P2 is formed at a portion of the end 117b that is radially outward of the bearing 9. The outlet P2 is located vertically above the inlet P1. A refrigerant outlet pipe 202 is connected to the outlet P2. For example, the outlet pipe 202 extends from the outlet P2 in a substantially horizontal direction and then bends vertically upward.

[0104] The direction of refrigerant flow during engine operation is indicated by arrow A1 in Figure 9. Specifically, refrigerant flowing through inlet pipe 201 is sent to straight flow path 118 through inlet P1. The refrigerant sent to straight flow path 118 flows approximately horizontally within straight flow path 118 and then sent to quadrant flow path 117. The refrigerant sent to quadrant flow path 117 flows circumferentially around bearing 9 within quadrant flow path 117 and then sent to outlet pipe 202 through outlet P2.

[0105] In the bearing housing 2-6, the refrigerant flow path 100 has a lower region R1 including a quadrant-shaped flow path 117 and a linear flow path 118, but does not have an upper region R2. As such, when viewed in the axial direction of the bearing 9, the refrigerant flow path 100 is disposed around the bearing 9, covering the vertically lower side of the bearing 9 but not the vertically upper side of the bearing 9. In the quadrant-shaped flow path 117, the vertical position of the refrigerant flow path 100 changes vertically upward as it progresses in the refrigerant flow direction. In the linear flow path 118, the vertical position of the refrigerant flow path 100 is maintained as it progresses in the refrigerant flow direction.

[0106] Thus, in the bearing housing 2-6, the vertical position of the refrigerant flow path 100 is maintained or changes vertically upward as the refrigerant flows in the direction of flow. Therefore, the vertical position of the refrigerant flow path 100 does not change vertically downward as the refrigerant flows in the direction of flow. In other words, there is no point where the vertical position of the refrigerant flow path 100 changes vertically downward as the refrigerant flows in the direction of flow. Therefore, when vapor V1 is generated in the refrigerant flow path 100, the vapor V1 rises due to buoyancy and is sent to the outflow pipe 202, making it less likely to accumulate in the refrigerant flow path 100.

[0107] As described above, in the bearing housing 2-6 according to the sixth modified example, the refrigerant flow path 100 is formed in the bearing housing 2 and is disposed around the bearing 9 when viewed in the axial direction of the bearing 9, covering the vertically lower side of the bearing 9. The vertical position of the refrigerant flow path 100 does not change vertically downward as the refrigerant flows in the direction of flow. Therefore, the downward gradient region DR does not exist in the refrigerant flow path 100. This prevents vapor V1 from accumulating in the refrigerant flow path 100 when the engine is stopped, thereby preventing a decrease in the cooling performance of the refrigerant flow path 100 when the engine is stopped.

[0108] 9 , the straight flow path 118 may be modified so that the vertical position of the straight flow path 118 moves vertically downward as it moves away from the end 117a. In this case, the vertical position of the refrigerant flow path 100 is not maintained throughout the entire refrigerant flow path 100, but moves vertically upward as the refrigerant progresses in the flow direction. This effectively prevents vapor V1 from accumulating in the refrigerant flow path 100 when the engine is stopped, thereby effectively preventing a decrease in the cooling performance of the refrigerant flow path 100 when the engine is stopped.

[0109] Although the embodiments of the present disclosure have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present disclosure.

[0110] 2: Bearing housing 2-1: Bearing housing 2-2: Bearing housing 2-3: Bearing housing 2-4: Bearing housing 2-5: Bearing housing 2-6: Bearing housing 9: Bearing 100: Refrigerant flow path BR: Branch chamber CP: Connection flow path P1: Inlet P2: Outlet R1: Lower region R2: Upper region TC: Turbocharger

Claims

1. A turbocharger comprising: a bearing housing that accommodates a bearing; a refrigerant flow path formed in the bearing housing, arranged around the bearing when viewed in the axial direction of the bearing, and including a refrigerant inlet and a refrigerant outlet located vertically above the inlet; a lower region of the refrigerant flow path that includes the inlet and covers the vertically below the bearing when viewed in the axial direction, and an upper region of the refrigerant flow path that includes the outlet and covers the vertically above the bearing when viewed in the axial direction, wherein in at least one of the lower region and upper region, the vertical position of the refrigerant flow path does not change vertically downward as the refrigerant proceeds in the flow direction.

2. The turbocharger according to claim 1, wherein in at least one of the lower region and the upper region, the vertical position of the refrigerant flow path is not maintained but changes vertically upward as the refrigerant progresses in the flow direction.

3. The turbocharger according to claim 1, wherein in both the lower region and the upper region, the vertical position of the refrigerant flow path does not change vertically downward as the refrigerant progresses in the flow direction.

4. The turbocharger according to claim 3, wherein in both the lower region and the upper region, the vertical position of the refrigerant flow path is not maintained but changes vertically upward as the refrigerant progresses in the flow direction.

5. A turbocharger according to any one of claims 1 to 4, comprising a branch chamber branching from the upper region and extending vertically downward.

6. The turbocharger according to claim 5, further comprising a connecting flow passage connecting the lower region and the branch chamber.

7. A turbocharger comprising: a bearing housing that accommodates a bearing; and a refrigerant flow path that is formed in the bearing housing, that is arranged around the bearing when viewed in the axial direction of the bearing, that covers the vertically lower or vertically upper side of the bearing, that includes a refrigerant inlet and a refrigerant outlet that is located vertically above the inlet, and whose vertical position does not change vertically downward as the refrigerant flows in the flow direction.

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