Supercharger

Abstract

A supercharger according to the present invention is provided with: a turbine rotor blade that is configured to be driven by exhaust gas discharged from an internal combustion engine; a stationary member that has a stationary wall surface facing the turbine rotor blade with a radial gap therebetween, and that includes a cylindrical section internally forming an outlet flow path through which flows the exhaust gas that has passed through the turbine rotor; a cooling medium passage which is provided adjacent to the stationary member and through which a cooling medium for cooling the stationary member can circulate; a cooling medium introduction line for guiding the cooling medium to the cooling medium passage; and a cooling medium flow rate adjustment device that is configured to be capable of adjusting the flow rate of the cooling medium guided to the cooling medium passage via the cooling medium introduction line, and that is configured to make the flow rate of the cooling medium guided to the cooling medium passage greater during low-load conditions of the internal combustion engine than during high-load conditions thereof.

Description

turbocharger

[0001] This application claims priority to Japanese Patent Application No. 2024-021911, filed with the Japan Patent Office on February 16, 2024, the contents of which are incorporated herein by reference.

[0002] Patent Document 1 discloses that a cooling passage through which engine cooling water flows is formed inside a shroud portion of a casing provided on the outer periphery of a turbine wheel.

[0003] Japanese Patent Application Laid-Open No. 2009-243277

[0004] Generally, the tip clearance (radial gap with a stationary member) of the turbine rotor blades of a supercharger is set to be optimal when the internal combustion engine is under high load. Therefore, when the internal combustion engine is under low load, the tip clearance of the turbine rotor blades increases, which may reduce the efficiency of the turbine of the supercharger.

[0005] The invention described in Patent Document 1 increases the amount of engine cooling water flowing through the cooling passage in response to an engine acceleration request, i.e., improves the efficiency of the turbocharger turbine when the engine is accelerating, but does not necessarily improve the efficiency of the turbocharger turbine when the engine is under low load.

[0006] In view of the above circumstances, at least one embodiment of the present disclosure has an object to provide a turbocharger that can improve the efficiency of the turbine of the turbocharger during low load operation.

[0007] A turbocharger according to at least one embodiment of the present disclosure includes: a turbine rotor blade configured to be driven by exhaust gas discharged from an internal combustion engine; a stationary member having a stationary wall surface facing the turbine rotor blade with a radial gap therebetween, the stationary member including a cylindrical portion forming an outlet flow path therein through which the exhaust gas that has passed through the turbine rotor blade flows; a cooling medium passage provided adjacent to the stationary member and through which a cooling medium for cooling the stationary member can flow; a cooling medium introduction line for introducing the cooling medium to the cooling medium passage; and a cooling medium flow control device configured to be able to adjust the flow rate of the cooling medium introduced to the cooling medium passage via the cooling medium introduction line, the cooling medium flow control device configured to increase the flow rate of the cooling medium introduced to the cooling medium passage when the internal combustion engine is under low load compared to when the internal combustion engine is under high load.

[0008] According to at least one embodiment of the present disclosure, a turbocharger capable of improving the efficiency of a turbine of the turbocharger during low load operation is provided.

[0009] FIG. 1 is a schematic view of an internal combustion engine system including a supercharger according to an embodiment of the present disclosure; FIG. 2 is a schematic view of a supercharger according to an embodiment of the present disclosure; FIG. 3 is a schematic view of a supercharger according to an embodiment of the present disclosure; FIG. 4 is a schematic view of a supercharger according to an embodiment of the present disclosure; FIG. 5 is a schematic view of a supercharger according to an embodiment of the present disclosure; FIG. 6 is a schematic view of a supercharger according to an embodiment of the present disclosure; FIG. 7 is a schematic cross-sectional view of a coolant flow path according to an embodiment of the present disclosure, viewed from one side in the axial direction; FIG. 8 is a schematic cross-sectional view of a coolant flow path according to an embodiment of the present disclosure, viewed from one side in the axial direction; FIG. 9 is a schematic view of a coolant flow path according to an embodiment of the present disclosure, viewed from the outside in the radial direction; FIG. 10 is a schematic view of a supercharger according to an embodiment of the present disclosure; FIG. 11 is a schematic view of a supercharger according to an embodiment of the present disclosure;

[0010] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure.

[0011] In the following description, when simply referring to the upstream side, it refers to the upstream side along the main flow direction of the fluid in the part or area described in the direction. Similarly, in the following description, when simply referring to the downstream side, it refers to the downstream side along the main flow direction of the fluid in the part or area described in the direction.

[0012] (Internal combustion engine system) Fig. 1 is a schematic diagram of an internal combustion engine system 1 including a supercharger 2 according to an embodiment of the present disclosure. Fig. 1 schematically shows a cross section along a central axis of rotation CA of the supercharger 2. The internal combustion engine system 1 includes an internal combustion engine 11 and a supercharger (turbocharger) 2 mounted on the internal combustion engine 11. In the following embodiment, a supercharger 2 mounted on a marine internal combustion engine will be described, but the supercharger 2 of the present disclosure may also be mounted on internal combustion engines other than those for marine use.

[0013] (Turbocharger) As shown in FIG. 1 , the turbocharger 2 includes a rotating shaft 21 extending along a central rotation axis CA, a bearing 22 that rotatably supports the rotating shaft 21, a turbine rotor blade 3, an impeller 4, and a casing 23 configured to house the rotating shaft 21, the bearing 22, the turbine rotor blade 3, and the impeller 4.

[0014] Hereinafter, the direction in which the rotational axis CA of the rotating shaft 21 extends (the left-right direction in FIG. 1 ) is defined as the axial direction of the rotating shaft 21 (supercharger 2), the direction perpendicular to the rotational axis CA is defined as the radial direction of the rotating shaft 21 (supercharger 2), and the circumferential direction centered on the rotational axis CA is defined as the circumferential direction of the rotating shaft 21 (supercharger 2). In the present disclosure, the axial direction, radial direction, and circumferential direction of the turbocharger 2 may be simply referred to as the axial direction, radial direction, and circumferential direction, respectively. Note that, in the present disclosure, "along a certain direction" includes not only a certain direction but also a direction inclined within a range of ±15° relative to the certain direction.

[0015] The turbine rotor blades 3 are attached to one axial side of the rotating shaft 21. The impeller 4 is attached to the other axial side of the rotating shaft 21. The bearing 22 is arranged between the turbine rotor blades 3 and the impeller 4 in the axial direction of the rotating shaft 21. The turbine rotor blades 3 and the impeller 4 are mechanically connected to each other via the rotating shaft 21 and are configured to be able to rotate integrally.

[0016] The turbine rotor blades 3 are provided in an exhaust flow path of the internal combustion engine 11. The impeller 4 is provided in an intake flow path of the internal combustion engine 11. The turbine rotor blades 3 are rotated by exhaust gas discharged from the internal combustion engine 11, and the impeller 4, which rotates in conjunction with the turbine rotor blades 3, compresses (supercharges) combustion gas (e.g., air) supplied to the internal combustion engine 11.

[0017] (Turbine rotor blades) In the illustrated embodiment, the rotating shaft 21 has a disk portion 211 that protrudes radially outward from the outer circumferential surface of the rotating shaft 21 on one axial side of the rotating shaft 21. A one-stage turbine rotor blade row made up of a plurality of turbine rotor blades 3 arranged in a row in the circumferential direction of the rotating shaft 21 is attached to the outer circumferential surface of the disk portion 211 of the rotating shaft 21.

[0018] Each of the plurality of turbine rotor blades 3 has a blade surface 31, a blade root 32 connected to the outer peripheral surface of the disk portion 211, and a tip end (tip end) 33 spaced further outward in the radial direction of the rotating shaft 21 than the blade root 32 with respect to the central rotation axis CA. Each of the plurality of turbine rotor blades 3 may be formed integrally with the rotating shaft 21, or may be separate from the rotating shaft 21 and fixed to the rotating shaft 21 by welding or the like.

[0019] 1 , the casing 23 includes a turbine housing 5 that rotatably accommodates the turbine rotor blades 3, a compressor housing 6 that rotatably accommodates the impeller 4, and a bearing stand 7 that accommodates the bearings 22. The bearing stand 7 is disposed between the turbine housing 5 and the compressor housing 6 in the axial direction of the rotating shaft 21, and is fastened to each of the turbine housing 5 and the compressor housing 6 via fastening members such as bolts.

[0020] (Impeller) The impeller 4 is configured to guide combustion gas guided along the axial direction radially outward. As shown in FIG. 1 , the impeller 4 includes a hub 41 having a front surface 42 and a back surface 43, and a plurality of blades 44 provided to protrude radially outward from the outer peripheral surface of the hub 41. The hub 41 is formed in a conical shape whose outer dimensions gradually increase as it moves away from the intake inlet 61 of the compressor housing 6 in the axial direction. The front surface 42 is the surface of the hub 41 near the intake inlet 61 in the axial direction, on which the blades 44 are provided. The back surface 43 is the surface of the hub 41 away from the intake inlet 61 in the axial direction.

[0021] 1, the compressor housing 6 is formed with an intake inlet 61 for introducing combustion gas from outside the compressor housing 6, and an intake outlet 62 for discharging the combustion gas compressed by rotation of the impeller 4 to the outside of the compressor housing 6. In the illustrated embodiment, the intake inlet 61 is formed on the end face on the other side in the axial direction of the compressor housing 6, and the intake outlet 62 is formed on the outer surface of the compressor housing 6 in the radial direction.

[0022] An intake inlet passage 63 for guiding combustion gas taken in from the intake inlet 61 to the impeller 4, and an intake outlet passage 64 for guiding combustion gas compressed by rotation of the impeller 4 to the intake outlet 62 are formed inside the compressor housing 6. The intake outlet passage 64 includes a diffuser 641 extending along the radial direction of the rotating shaft 21 on the outer periphery side of the impeller 4, and a scroll passage 642 formed in a spiral shape that communicates with the diffuser 641 and extends along the circumferential direction of the rotating shaft 21 on the outer periphery side of the diffuser 641. The compressor housing 6 has a shroud portion 66 formed to cover the impeller 4.

[0023] The combustion gas introduced into the compressor housing 6 flows between the multiple blades 44 of the rotationally driven impeller 4, mainly increasing its dynamic pressure, and then flows into the diffuser 641 located radially outward, where part of the dynamic pressure is converted into static pressure, increasing the pressure, and is then sent into the combustion chamber of the internal combustion engine 11 through the scroll passage 642 and the intake port 62. At this time, part of the combustion gas whose pressure has been increased by the impeller 4 passes through a gap formed between the outer circumferential end of the impeller 4 and a portion of the bearing base 7 facing the outer circumferential end of the impeller 4, and flows into an impeller back space 67 formed on the back surface 43 side of the impeller 4.

[0024] The impeller back-side space 67 is an internal space facing the back surface 43 of the impeller 4, and is an internal space into which combustion gas compressed by the rotation of the impeller 4 flows. In the illustrated embodiment, the impeller back-side space 67 is a space at least partially defined by the back surface 43 of the impeller 4 and the end face 71 on the other axial side of the bearing base 7. Note that the impeller back-side space 67 may also be a space at least partially defined by the back surface 43 of the impeller 4 and a portion of the compressor housing 6 facing the back surface 43. The impeller back-side space 67 may also be partially defined by a member housed in the compressor housing 6 or the bearing base 7.

[0025] 1 , the turbine housing 5 is formed with an exhaust gas inlet 53 for introducing exhaust gas from outside the turbine housing 5, and an exhaust gas outlet 54 for discharging exhaust gas that has passed through the turbine rotor blades 3 to the outside of the turbine housing 5. In the illustrated embodiment, the turbine housing 5 includes an inlet-side housing 51 in which the exhaust gas inlet 53 is formed, and an outlet-side housing 52 in which the exhaust gas outlet 54 is formed on an outer surface in the radial direction. The outlet-side housing 52 is disposed between the bearing stand 7 and the inlet-side housing 51 in the axial direction of the rotating shaft 21, and is fastened to the bearing stand 7 and the inlet-side housing 51 via fastening members such as bolts.

[0026] An exhaust gas inlet passage 55 is formed inside the inlet housing 51 for guiding exhaust gas that has entered through the exhaust gas inlet 53 to the turbine rotor blades 3. An exhaust gas outlet passage 56 is formed inside the outlet housing 52 for guiding exhaust gas that has passed through the turbine rotor blades 3 to the exhaust gas outlet 54. Relatively high-temperature exhaust gas discharged from the internal combustion engine 11 is introduced into the turbine housing 5 from the exhaust gas inlet 53 and sent to the turbine rotor blades 3, thereby driving the turbine rotor blades 3 to rotate about the central rotation axis CA. The exhaust gas that has driven the turbine rotor blades 3 to rotate is discharged from the exhaust gas outlet 54.

[0027] (Stationary Member) As shown in Fig. 1 , the turbocharger 2 includes a stationary member 8 including at least a cylindrical portion 81. The cylindrical portion 81 has a stationary wall surface 82A that faces the turbine rotor blades 3 with a radial gap C therebetween. In the illustrated embodiment, the cylindrical portion 81 is formed in an annular shape that covers a radially inner wall surface 521 of the outlet-side housing 52 via the radial gap. An annular flow passage 57 extending along the axial direction of the rotating shaft 21 is formed between an inner circumferential surface 82 including the stationary wall surface 82A of the cylindrical portion 81 and the wall surface 521 of the outlet-side housing 52. The annular flow passage 57 is a flow passage for guiding exhaust gas, which is the working fluid of the turbine rotor blades 3, from the one axial side (right side in Fig. 1 ) to the other axial side (left side in Fig. 1 ) of the rotating shaft 21.

[0028] Each of the plurality of turbine rotor blades 3 described above is arranged in the annular flow path 57. The tip end 33 of each of the plurality of turbine rotor blades 3 faces a stationary wall surface 82A, which is a part of the inner circumferential surface 82, via a radial gap C.

[0029] An upstream outlet flow path (outlet flow path) 56A connected to the downstream side of the annular flow path 57 is formed between an inner circumferential surface 83 connected to the inner circumferential surface 82 of the cylindrical portion 81 and a wall surface 521 of the outlet housing 52. The upstream outlet flow path 56A is a flow path for guiding exhaust gas that has passed through the annular flow path 57 radially outward. The inner circumferential surface 83 is formed on the other axial side (left side in FIG. 1 ) of the inner circumferential surface 82. The cylindrical portion 81 is inclined so that the distance (radial distance) of the inner circumferential surface 83 from the rotation center axis CA increases toward the other side.

[0030] The exhaust gas outlet flow path 56 includes an upstream outlet flow path 56A and a downstream outlet flow path 56B that is connected to the downstream side of the upstream outlet flow path 56A. The exhaust gas flowing through the downstream outlet flow path 56B has a lower temperature than the exhaust gas flowing through the annular flow path 57 and the upstream outlet flow path 56A. The cylindrical portion 81 has inner circumferential surfaces 82 and 83 that face the annular flow path 57 and the upstream outlet flow path 56A, and an outer circumferential surface 84 that faces the downstream outlet flow path 56B. Therefore, the temperature gradient between the inner circumferential surfaces 82 and 83 and the outer circumferential surface 84 is high, and a large amount of heat is transferred from the exhaust gas flowing through the annular flow path 57 and the upstream outlet flow path 56A.

[0031] In the illustrated embodiment, the stationary member 8 further includes a support arm portion 85 extending radially outward from an inner peripheral end portion 851 connected to the outer peripheral surface of the cylindrical portion 81, and having an outer peripheral end portion 852 supported by the casing 23. The support arm portion 85 is formed in an annular shape extending along the circumferential direction of the rotating shaft 21. In a cross section taken along the central axis of rotation CA as shown in FIG. 1 , the support arm portion 85 includes an inclined side portion 853 inclined toward the one axial side (the right side in FIG. 1 ) as it extends radially outward from the inner peripheral end portion 851, an axial side portion 854 extending from the outer peripheral end portion of the inclined side portion 853 along the axial direction to the one axial side, and a radial side portion 855 extending radially outward from the one end portion of the axial side portion 854 along the radial direction. The radial side portion 855 has the outer peripheral end portion 852 described above.

[0032] Since the outer peripheral end 852 of the support arm portion 85 is sandwiched between the inlet side housing 51 and the outlet side housing 52, the radial thermal expansion of the stationary member 8 due to heat transfer from the exhaust gas is limited.

[0033] In the illustrated embodiment, the outer peripheral end 852 of the support arm portion 85 is sandwiched between the inlet-side housing 51 and the outlet-side housing 52, but it may be configured to be fixed to either the inlet-side housing 51 or the outlet-side housing 52. Also, in the illustrated embodiment, the stationary member 8 is separate from the inlet-side housing 51 and the outlet-side housing 52, but it may be formed integrally with the inlet-side housing 51 or the outlet-side housing 52, in which case the configuration may not include the support arm portion 85.

[0034] In the illustrated embodiment, an annular hollow space 58 extending along the circumferential direction of the rotary shaft 21 is formed between the cylindrical portion 81 , the support arm portion 85 and the inlet side housing 51 .

[0035] When the load on the internal combustion engine 11 increases, the temperature of the exhaust gas introduced into the turbine rotor blades 3 rises, and the amount of heat transferred to the turbine rotor blades 3 and the stationary member 8 increases, causing relatively large thermal elongation in the turbine rotor blades 3 and the stationary member 8. When the load on the internal combustion engine 11 increases, the rotation speed of the turbine rotor blades 3 increases, causing relatively large elongation in the turbine rotor blades 3 due to centrifugal force. Because the stationary member 8 is supported by the turbine housing 5 or is formed integrally with the turbine housing 5, its structure restricts thermal elongation in the radial direction, making it difficult for it to undergo thermal elongation similar to that of the turbine rotor blades 3 in response to the load on the internal combustion engine 11.

[0036] Generally, the tip clearance (radial gap C) of the turbine rotor blades 3 is set to be optimal when the internal combustion engine 11 is under high load, so when the internal combustion engine 11 is under low load, the tip clearance of the turbine rotor blades 3 increases, which may reduce the efficiency of the turbine of the turbocharger 2.

[0037] 2 to 8 are schematic diagrams of a turbocharger 2 according to an embodiment of the present disclosure. 2 to 8 schematically show half cross sections of the turbocharger 2 taken along a central axis of rotation CA. As shown in FIGS. 2 to 6, the turbocharger 2 includes a cooling medium passage 9 that is provided adjacent to the stationary member 8 and through which a cooling medium for cooling the stationary member 8 can flow, a cooling medium inlet line 92 that guides the cooling medium from a supply source to the cooling medium passage 9, a cooling medium discharge line 93 that guides the cooling medium discharged from the cooling medium passage 9 to a cooling medium discharge destination, and a cooling medium flow control device 94 that is configured to adjust the flow rate of the cooling medium guided to the cooling medium passage 9 via the cooling medium inlet line 92.

[0038] The cooling medium passage 9 is provided inside the turbine housing 5. In the embodiment shown in Figures 2 to 8, the cooling medium passage 9 includes a cooling pipe 91 having an internal space 90 through which the cooling medium can flow. Each of the cooling medium inlet line 92 and the cooling medium discharge line 93 may be any line that forms a flow path for circulating the cooling medium, and may include a hole or hollow portion formed in a solid portion of the casing 23, or may include external piping arranged outside the casing 23.

[0039] The coolant flow rate control device 94 is configured to increase the flow rate of the coolant introduced into the coolant passage 9 when the internal combustion engine 11 is under low load compared to when the internal combustion engine 11 is under high load. In the illustrated embodiment, the coolant flow rate control device 94 includes either a flow rate control valve 95 provided in the coolant inlet line 92 or a flow rate control valve 96 provided in the coolant discharge line 93, and a controller 97 for controlling the opening and closing operations of the flow rate control valves 95, 96. The flow rate control valves 95, 96 may be open / close valves whose opening degree can be adjusted between fully closed and fully open, or may be opening degree control valves whose opening degree can be adjusted to fully closed, fully open, and at least one intermediate opening degree therebetween.

[0040] The controller 97 is an electronic control unit for controlling the opening and closing operations of the flow rate adjustment valves 95, 96, and is configured as a microcomputer including a CPU (processor) (not shown), memories such as ROM and RAM, storage devices such as external storage devices, an I / O interface, a communication interface, etc. Information (signals) relating to the load of the internal combustion engine 11 is sent to the controller 97 from the internal combustion engine 11, etc. The controller 97 controls the opening and closing operations of the flow rate adjustment valves 95, 96 in accordance with the information relating to the load of the internal combustion engine 11.

[0041] In one embodiment, when the load of the internal combustion engine 11 exceeds a set load that is set as a boundary between a low load and a high load, the controller 97 executes an opening degree instruction to reduce the opening degree of the flow rate adjustment valves 95, 96. At this time, the controller 97 may execute an opening degree instruction to fully close the flow rate adjustment valves 95, 96. Furthermore, when the load of the internal combustion engine 11 is less than the set load, the controller 97 may keep the opening degree of the flow rate adjustment valves 95, 96 constant.

[0042] By relatively increasing the flow rate of the cooling medium introduced into the cooling medium passage 9 when the internal combustion engine 11 is under low load, thereby increasing the cooling effect of the cooling medium on the stationary member 8 and suppressing radial thermal expansion of the stationary member 8, it is possible to suppress an increase in the tip clearance (radial gap C) of the turbine rotor blades 3 when the internal combustion engine 11 is under low load. By suppressing an increase in the tip clearance of the turbine rotor blades 3 when the internal combustion engine 11 is under low load, it is possible to improve the efficiency of the turbocharger turbine when the internal combustion engine 11 is under low load.

[0043] 2 to 8, the cooling medium is lubricating oil. By using lubricating oil, which may be used to lubricate equipment (e.g., bearings 22) mounted on the turbocharger 2, to cool the stationary member 8, an existing lubricating oil supply system can be reused, eliminating the need to provide a new, separate lubricating oil system, and thus preventing the structure of the internal combustion engine system 1 including the turbocharger 2 from becoming more complex.

[0044] In the embodiment shown in FIGS. 2 to 6 , a lubricant oil storage space 72 configured to store lubricant oil is formed inside the bearing stand 7. The turbocharger 2 includes a lubricant oil storage device 101 provided outside the bearing stand 7 (casing 23) and configured to store lubricant oil, a lubricant oil introduction line 102 for guiding the lubricant oil from the lubricant oil storage device 101 to the lubricant oil storage space 72, and a lubricant oil recovery line 103 for recovering the lubricant oil from the lubricant oil storage space 72 via a lubricant oil supply destination such as the bearing 22 and returning it to the lubricant oil storage device 101. The lubricant oil introduction line 102 is provided with a lubricant oil pump 104 for pressurizing the lubricant oil and a lubricant oil cooler 105 for cooling the lubricant oil. In the illustrated embodiment, the lubricant oil cooler 105 is provided downstream of the lubricant oil pump 104 on the lubricant oil introduction line 102.

[0045] (Connection Destination of Cooling Medium Inlet Line) As shown in FIGS. 2 to 5 , the cooling medium inlet line 92 may be connected to the lubricant oil inlet line 102. In the illustrated embodiment, the cooling medium inlet line 92 is connected to a connection point P1 of the lubricant oil inlet line 102 downstream of the lubricant oil cooler 105. In this case, the lubricant oil stored in the lubricant oil storage device 101 can be introduced into the cooling medium passage 9 via the cooling medium inlet line 92 and a portion of the lubricant oil inlet line 102 upstream of the connection point P1 with the cooling medium inlet line 92. Since the equipment constituting the lubricant oil circulation system (the lubricant oil storage device 101, the lubricant oil inlet line 102, the lubricant oil recovery line 103, the lubricant oil pump 104, and the lubricant oil cooler 105) can be used as equipment for cooling the stationary member 8, the lubricant oil can be used to cool the stationary member 8 while suppressing the complexity of the structure of the internal combustion engine system 1 including the turbocharger 2.

[0046] 6 , the above-described cooling medium introduction line 92 may be connected to the lubricating oil storage space 72. In this case, the lubricating oil stored in the lubricating oil storage space 72 can be introduced into the cooling medium passage 9 via the cooling medium introduction line 92. This allows the equipment constituting the lubricating oil circulation system to be used as equipment for cooling the stationary members 8, so that the lubricating oil can be used to cool the stationary members 8 while suppressing an increase in the complexity of the structure of the internal combustion engine system 1 including the turbocharger 2.

[0047] (Connection Destination of Cooling Medium Discharge Line) The above-described cooling medium discharge line 93 may be connected to the lubricating oil storage space 72, as shown in Fig. 2. The lubricating oil (cooling medium) flowing through the cooling medium discharge line 93 recovers thermal energy from the stationary member 8 in the cooling medium passage 9. By introducing the lubricating oil flowing through the cooling medium discharge line 93 into the lubricating oil storage space 72, the temperature of the lubricating oil stored in the lubricating oil storage space 72 can be increased. By increasing the temperature of the lubricating oil stored in the lubricating oil storage space 72, the viscosity of the lubricating oil can be reduced, and mechanical loss of the equipment (e.g., bearing 22) to which the lubricating oil is supplied can be reduced.

[0048] The above-mentioned cooling medium discharge line 93 may be connected to a lubricating oil storage device 101, as shown in Fig. 5. By discharging the cooling medium that has flowed through the cooling medium passage 9 to the lubricating oil storage device 101 provided outside the bearing pedestal 7, rather than to the lubricating oil storage space 72 formed inside the bearing pedestal 7, the structures of the cooling medium discharge line 93 and the bearing pedestal 7 can be simplified.

[0049] 3 and 4 , the above-described cooling medium discharge line 93 may be provided with a heat exchanger 98 configured to perform heat exchange between the lubricating oil stored in the lubricating oil storage space 72 and the lubricating oil flowing through the cooling medium discharge line 93. In the embodiment shown in FIGS. 3 and 4 , the cooling medium discharge line 93 provided with the heat exchanger 98 is connected to a lubricating oil storage device 101.

[0050] In the embodiment shown in FIG. 3 , an internal space 981 through which lubricating oil can flow is formed inside a solid portion of the lubricating oil storage space forming portion 721 that forms the lubricating oil storage space 72 of the bearing stand 7. The internal space 981 is formed on the one axial side (the right side in the figure) of the lubricating oil storage space 72 at a position corresponding to the lubricating oil storage space 72. Forming the internal space 981 at a position corresponding to the lubricating oil storage space 72 means that at least a portion of the internal space 981 is located at the radial and circumferential positions where the lubricating oil storage space 72 is located. The lubricating oil storage space forming portion 721 includes a partition wall 722 that extends in a direction intersecting (orthogonal to) the axial direction and separates the lubricating oil storage space 72 from the internal space 981. The internal space 981 is adjacent to the lubricating oil storage space 72 across the partition wall 722. In the embodiment shown in FIG. 3 , the heat exchanger 98 is configured to perform heat exchange between the lubricating oil flowing through the internal space 981 and the lubricating oil stored in the lubricating oil storage space 72. By heat exchange in the heat exchanger 98 , the thermal energy of the lubricating oil flowing through the internal space 981 is transferred to the lubricating oil stored in the lubricating oil storage space 72 .

[0051] In the embodiment shown in FIG. 4 , the heat exchanger 98 is provided in the cooling medium discharge line 93 and includes a heat transfer tube 982 through which lubricating oil flows. In the example shown in FIG. 4 , the heat transfer tube 982 is formed in a so-called S-shape and abuts against a wall surface 723 on one axial side (the right side in the figure) of a lubricating oil storage space forming portion 721 that forms the lubricating oil storage space 72 of the bearing base 7. The heat transfer tube 982 is formed at a position corresponding to the lubricating oil storage space 72. Forming at a position corresponding to the lubricating oil storage space 72 means that at least a portion of the heat transfer tube 982 is located at the radial and circumferential positions where the lubricating oil storage space 72 is located. The lubricating oil storage space forming portion 721 includes a wall 724 that extends in a direction intersecting (orthogonal to) the axial direction and separates the lubricating oil storage space 72 from a space in which the heat transfer tube 982 is located. The wall 724 has a wall surface 723. The heat transfer tube 982 is adjacent to the lubricant oil storage space 72 across the wall 724. In the embodiment shown in Fig. 4, the heat exchange unit 98 is configured to perform heat exchange between the lubricant oil flowing through the heat transfer tube 982 and the lubricant oil stored in the lubricant oil storage space 72. Through the heat exchange in the heat exchange unit 98, the thermal energy of the lubricant oil flowing through the heat transfer tube 982 is transferred to the lubricant oil stored in the lubricant oil storage space 72. Note that in other embodiments, the heat transfer tube 982 may be disposed inside the solid portion of the lubricant oil storage space forming portion 721 (for example, inside the wall 724).

[0052] The lubricating oil (cooling medium) flowing through the cooling medium discharge line 93 recovers thermal energy from the stationary member 8 in the cooling medium passage 9. The thermal energy recovered from the stationary member 8 is transferred to the lubricating oil stored in the lubricating oil storage space 72 through heat exchange in the heat exchanger 98, thereby raising the temperature of the lubricating oil stored in the lubricating oil storage space 72. By raising the temperature of the lubricating oil stored in the lubricating oil storage space 72, the viscosity of the lubricating oil can be reduced, and mechanical loss of the equipment (e.g., bearing 22) to which the lubricating oil is supplied can be reduced.

[0053] 2 to 6 , the cooling pipe 91 (cooling medium passage 9) described above is arranged more outer circumferentially than the cylindrical portion 81, and is arranged at an axial position corresponding to the turbine rotor blade 3. Arranged at an axial position corresponding to the turbine rotor blade 3 means that at least a portion of the cooling pipe 91 is present at the axial position where the turbine rotor blade 3 is present. In the embodiment shown in FIGS. 2 to 6 , the cooling pipe 91 is arranged in the hollow space 58, and is adapted to abut against an outer circumferential surface formed at an axial position corresponding to the stationary wall surface 82A of the cylindrical portion 81 that faces the hollow space 58.

[0054] The axial position of the cylindrical portion 81 corresponding to the turbine rotor blade 3 is a position that has a relatively large effect on the tip clearance of the turbine rotor blade 3, and by cooling this position with a cooling medium, it is possible to effectively suppress an increase in the tip clearance of the turbine rotor blade 3 during low load conditions.

[0055] 7 and 8 show modified examples of the cooling pipe 91 (cooling medium passage 9) described above. In FIGS. 7 and 8, the cooling medium inlet line 92 and the cooling medium outlet line 93 connected to the cooling pipe 91 are omitted, but the cooling medium inlet line 92 and the cooling medium outlet line 93 may be the same as those shown in FIGS. 2 to 6.

[0056] In some embodiments, as shown in Figures 7 and 8, the cooling pipe 91 (cooling medium passage 9) is arranged in contact with the support arm portion 85. In the embodiment shown in Figure 7, the cooling pipe 91 is arranged in the downstream outlet flow path 56B and in contact with the wall surface on the other axial side (left side in Figure 7) of the support arm portion 85. In the embodiment shown in Figure 8, the cooling pipe 91 is arranged in the hollow space 58 and in contact with the wall surface on the one axial side (right side in Figure 8) of the support arm portion 85. It is preferable that the cooling pipe 91 has a shape that follows the wall surface of the support arm portion 85 with which it abuts, in a cross section taken along the central axis of rotation CA as shown in Figures 7 and 8.

[0057] 7 , the cooling pipe 91 includes, in a cross section taken along the central axis of rotation CA, an inclined side portion 91A extending along the inclined side portion 853 and abutting against the inclined side portion 853, an axial side portion 91B extending along the axial side portion 854 and abutting against the axial side portion 854, and a radial side portion 91C extending along the radial side portion 855 and abutting against the radial side portion 855. Note that the cooling pipe 91 may be configured with one or two of the inclined side portion 91A, the axial side portion 91B, and the radial side portion 91C.

[0058] 8 , the cooling pipe 91 includes, in a cross section taken along the central axis of rotation CA, an inclined side portion 91D that extends along the inclined side portion 853 and abuts against the inclined side portion 853, an axial side portion 91E that extends along the axial side portion 854 and abuts against the axial side portion 854, and a radial side portion 91F that extends along the radial side portion 855 and abuts against the radial side portion 855. Note that the cooling pipe 91 may be configured with one or two of the inclined side portion 91D, the axial side portion 91E, and the radial side portion 91F.

[0059] The support arm portions 85 undergo thermal expansion in the radial direction due to heat transfer from the exhaust gas, and therefore have a relatively large effect on the tip clearance of the turbine rotor blades 3. By cooling the support arm portions 85 with a cooling medium, it is possible to effectively suppress an increase in the tip clearance of the turbine rotor blades 3 during low load operation.

[0060] (Shape of Cooling Medium Passage) Figures 9 and 10 are schematic cross-sectional views of a cooling medium passage 9 according to an embodiment of the present disclosure, viewed from one side in the axial direction. Figure 11 is a schematic view of a cooling medium passage 9 according to an embodiment of the present disclosure, viewed from the outside in the radial direction. The shapes of the cooling medium passage 9 shown in Figures 9 to 11 are applicable to the cooling medium passage 9 shown in Figures 2 to 8.

[0061] 9 and 10 , the cooling pipe 91 (cooling medium passage 9) described above includes an annular pipe extending along the circumferential direction of the turbocharger 2. In this case, the cooling medium flowing through the internal space 90 of the cooling pipe 91 can cool the stationary member 8 over a wide range in the circumferential direction of the turbocharger 2. Note that, in other embodiments, the cooling pipe 91 (cooling medium passage 9) described above may be an arc-shaped pipe extending halfway around or more (preferably three-quarters of the way around or more) along the circumferential direction of the turbocharger 2.

[0062] As shown in FIG. 10 , the above-mentioned cooling pipe 91 (cooling medium passage 9) may include at least one protrusion 913, 914 that protrudes from inner surfaces 911, 912 of the cooling pipe 91 and has a wall surface that extends along a direction intersecting the circumferential direction of the turbocharger 2.

[0063] 10 , the cooling pipe 91 includes a plurality of protrusions 913 protruding from an outer inner surface 911 in the radial direction of the cooling pipe 91 and a plurality of protrusions 914 protruding from an inner inner surface 912 in the radial direction of the cooling pipe 91. The plurality of protrusions 913 and the plurality of protrusions 914 are alternately arranged at intervals in the circumferential direction. Note that in other embodiments, the cooling pipe 91 may include either the plurality of protrusions 913 or the plurality of protrusions 914. Providing the protrusions 913, 914 on the inner surfaces 911, 912 of the cooling pipe 91 increases the amount of heat transferred from the cooling medium flowing inside the cooling pipe 91 to the cooling pipe 91, thereby increasing the amount of heat recovered by the cooling medium from the stationary member 8.

[0064] 11 , the cooling pipe 91 (cooling medium passage 9) includes a first long pipe portion 915, a second long pipe portion 916, a third long pipe portion 917, a first curved pipe portion 918, and a second curved pipe portion 919. When viewed from the outside in the radial direction, the first long pipe portion 915, the second long pipe portion 916, and the third long pipe portion 917 each extend along the axial direction of the turbocharger 2. The third long pipe portion 917 is disposed between the first long pipe portion 915 and the second long pipe portion 916 in the circumferential direction of the turbocharger 2. When viewed from the outside in the radial direction, the first curved pipe portion 918 has a curved shape connecting one axial end of the first long pipe portion 915 and one axial end of the second long pipe portion 916. When viewed from the outside in the radial direction, the second curved pipe portion 919 has a curved shape that connects the other axial end of the second long pipe portion 916 and the other axial end of the third long pipe portion 917.

[0065] By forming the cooling medium passage 9 in a so-called S-shape including the first long pipe portion 915, the second long pipe portion 916, the third long pipe portion 917, the first curved pipe portion 918, and the second curved pipe portion 919, the heat transfer area can be increased, and the heat transfer amount can be increased. Increasing the heat transfer amount of the cooling medium passage 9 can increase the amount of heat recovered by the cooling medium from the stationary member 8.

[0066] Fig. 12 is a schematic diagram of a turbocharger 2 according to an embodiment of the present disclosure. In the embodiment shown in Fig. 12, the above-mentioned cooling medium is cooling water. By using cooling water that may be used to cool the turbocharger 2 or the internal combustion engine 11 on which the turbocharger 2 is mounted, to cool the stationary member 8, an existing cooling water supply system can be reused, and there is no need to provide a new separate cooling water system, which makes it possible to suppress the complexity of the structure of the internal combustion engine system 1 including the turbocharger 2. Note that the positions and shapes of the cooling medium passages 9 shown in Figs. 2 to 11 may be applied to the turbocharger 2 shown in Fig. 12.

[0067] 12 , the turbocharger 2 includes a cooling water storage device 201 that is provided outside the casing 23 and configured to store cooling water, a cooling water inlet line 202 that guides the cooling water from the cooling water storage device 201 to the internal combustion engine 11, and a cooling water recovery line 203 that recovers the cooling water from the internal combustion engine 11 to the cooling water storage device 201. A cooling water pump 204 that increases the pressure of the cooling water and a cooling water cooler 205 that cools the cooling water are provided in the cooling water inlet line 202. In the illustrated embodiment, the cooling water cooler 205 is provided downstream of the cooling water pump 204 on the cooling water inlet line 202.

[0068] 12 , the above-described coolant introduction line 92 may be connected to a cooling water introduction line 202. In the illustrated embodiment, the coolant introduction line 92 is connected to a connection point P2 of the coolant introduction line 202 downstream of the coolant cooler 205. In the illustrated embodiment, the coolant discharge line 93 is connected to the cooling water storage device 201, but may be connected to a cooling water recovery line 203.

[0069] In this case, the cooling water stored in the cooling water storage device 201 can be introduced into the cooling medium passage 9 via the cooling medium introduction line 92 and a portion of the cooling water introduction line 202 upstream of the connection portion with the cooling medium introduction line 92. Since the equipment constituting the cooling water circulation system (the cooling water storage device 201, the cooling water introduction line 202, the cooling water recovery line 203, the cooling water pump 204, and the cooling water cooler 205) can be used as equipment for cooling the stationary member 8, the cooling water can be used to cool the stationary member 8 while suppressing the complexity of the structure of the internal combustion engine system 1 including the turbocharger 2.

[0070] In some embodiments, the above-mentioned cooling medium inlet line 92 includes the above-mentioned heat exchange section 98 (see Figures 3 and 4) configured to perform heat exchange between the lubricating oil stored in the lubricating oil storage space 72 and the cooling water (cooling medium) flowing through the cooling medium discharge line 93.

[0071] Fig. 13 is a schematic diagram of a turbocharger 2 according to an embodiment of the present disclosure. In the embodiment shown in Fig. 13, the above-mentioned cooling medium is the combustion gas that has flowed into the impeller back-side space 67. The above-mentioned cooling medium introduction line 92 is connected to the impeller back-side space 67. In this case, the combustion gas that has flowed into the impeller back-side space 67 can be used to cool the stationary member 8.

[0072] 2 to 11 may be applied to the turbocharger 2 shown in Fig. 13. When the hollow space 58 described above has a predetermined level of airtightness, the hollow space 58 itself may serve as the cooling medium passage 9 instead of the cooling pipe 91.

[0073] In this specification, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions expressing that things are in an equal state, such as "identical," "equal," and "homogeneous," not only express a state in which there is a strict equivalence, but also express a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions expressing shapes such as a rectangular shape or a cylindrical shape not only express shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components.

[0074] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0075] The contents of the above-described embodiments can be understood, for example, as follows.

[0076] 1) A turbocharger (2) according to at least one embodiment of the present disclosure includes: a turbine rotor blade (3) configured to be driven by exhaust gas discharged from an internal combustion engine (11); a stationary member (8) having a stationary wall surface (82) facing the turbine rotor blade (3) across a radial gap (C) and including a cylindrical portion (81) forming an outlet flow path (56) therein through which the exhaust gas that has passed through the turbine rotor blade (3) flows; a cooling medium passage (9) provided adjacent to the stationary member (8) and through which a cooling medium for cooling the stationary member (8) can flow; and a cooling medium introduction line (92) for introducing the cooling medium to the cooling medium passage (9). a cooling medium flow rate control device (94) configured to be able to adjust the flow rate of the cooling medium introduced into the cooling medium passage (9) via the cooling medium introduction line (92), and configured to increase the flow rate of the cooling medium introduced into the cooling medium passage (9) when the internal combustion engine (11) is under low load compared to when the internal combustion engine (11) is under high load.

[0077] According to the configuration 1), the flow rate of the cooling medium introduced into the cooling medium passage 9 is relatively increased when the internal combustion engine 11 is under low load, thereby increasing the cooling effect of the cooling medium on the stationary member 8 and suppressing radial thermal expansion of the stationary member 8, thereby suppressing an increase in the tip clearance (radial gap C) of the turbine rotor blades 3 when the internal combustion engine 11 is under low load. By suppressing an increase in the tip clearance of the turbine rotor blades 3 when the internal combustion engine 11 is under low load, the efficiency of the turbocharger turbine when the internal combustion engine 11 is under low load can be improved.

[0078] 2) In some embodiments, in the turbocharger (2) described in 1), the cooling medium is lubricating oil.

[0079] According to the configuration of 2) above, by using lubricating oil, which may be used to lubricate equipment (e.g., bearings 22) mounted on the turbocharger (2), to cool the stationary member (8), it is possible to suppress the structure of the internal combustion engine system (1) including the turbocharger (2) from becoming complicated.

[0080] 3) In some embodiments, the turbocharger (2) according to 2) above comprises: a bearing stand (7) configured to accommodate a bearing (22) that rotatably supports a rotating shaft (21) attached to one side of the turbine rotor blade (3) in the axial direction, and having a lubricant oil storage space (72) formed therein that is configured to store lubricant oil; a lubricant oil storage device (101) provided outside the bearing stand (7) and configured to store lubricant oil; and a lubricant oil introduction line (102) for introducing the lubricant oil from the lubricant oil storage device (101) to the lubricant oil storage space (72), and the cooling medium introduction line (92) is connected to the lubricant oil introduction line (102).

[0081] According to the configuration of 3), the lubricating oil stored in the lubricating oil storage device (101) can be introduced into the cooling medium passage (9) via the cooling medium introduction line (92) and a portion of the lubricating oil introduction line (102) upstream of the connection portion with the cooling medium introduction line (92). This makes it possible to use the lubricating oil to cool the stationary member (8) while suppressing the complexity of the structure of the internal combustion engine system (1) including the turbocharger (2).

[0082] 4) In some embodiments, the turbocharger (2) according to 2) above includes a bearing stand (7) configured to accommodate a bearing (22) that rotatably supports a rotating shaft (21) attached to one side of the turbine rotor blades (3) in the axial direction, and having a lubricant oil storage space (72) formed therein that is configured to store lubricant oil; and a lubricant oil storage device (101) that is provided outside the bearing stand (7) and configured to store lubricant oil, and the cooling medium introduction line (92) is connected to the lubricant oil storage space (72).

[0083] According to the configuration 4) above, the lubricating oil stored in the lubricating oil storage space (72) can be introduced into the cooling medium passage (9) via the cooling medium introduction line (92). This makes it possible to use the lubricating oil to cool the stationary member (8) while suppressing the complexity of the structure of the internal combustion engine system (1) including the turbocharger (2).

[0084] 5) In some embodiments, the turbocharger (2) according to any one of 2) to 4) above comprises: a bearing stand (7) configured to accommodate a bearing (22) that rotatably supports a rotating shaft (21) attached to one side of the turbine rotor blades (3) in an axial direction, and having a lubricant oil storage space (72) formed therein that is configured to store lubricant oil; a lubricant oil storage device (101) provided outside the bearing stand (7) and configured to store lubricant oil; a lubricant oil introduction line (102) for guiding the lubricant oil from the lubricant oil storage device (101) to the lubricant oil storage space (72); and a cooling medium discharge line (93) for guiding the cooling medium discharged from the cooling medium passage (9), wherein the cooling medium discharge line (93) includes a heat exchanger (98) configured to exchange heat between the lubricant oil stored in the lubricant oil storage space (72) and the lubricant oil flowing through the cooling medium discharge line (93).

[0085] According to the configuration of 5) above, the lubricating oil (cooling medium) flowing through the cooling medium discharge line (93) recovers thermal energy from the stationary member (8) in the cooling medium passage (9). The thermal energy recovered from the stationary member (8) is transferred to the lubricating oil stored in the lubricating oil storage space (72) through heat exchange in the heat exchange unit (98), thereby raising the temperature of the lubricating oil stored in the lubricating oil storage space (72). By raising the temperature of the lubricating oil stored in the lubricating oil storage space (72), the viscosity of the lubricating oil can be reduced, thereby reducing mechanical loss in equipment (e.g., bearings 22) to which the lubricating oil is supplied.

[0086] 6) In some embodiments, the turbocharger (2) according to any one of 2) to 4) above comprises: a bearing stand (7) configured to accommodate a bearing (22) that rotatably supports a rotating shaft (21) attached to one side of the turbine rotor blade (3) in the axial direction, and having a lubricant oil storage space (72) formed therein that is configured to store lubricant oil; a lubricant oil storage device (101) provided outside the bearing stand (7) and configured to store lubricant oil; a lubricant oil introduction line (102) for guiding the lubricant oil from the lubricant oil storage device (101) to the lubricant oil storage space (72); and a cooling medium discharge line (93) for guiding the cooling medium discharged from the cooling medium passage (9), wherein the cooling medium discharge line (93) is connected to the lubricant oil storage space (72).

[0087] According to the configuration 6) above, the lubricating oil (cooling medium) flowing through the cooling medium discharge line (93) recovers thermal energy from the stationary member (8) in the cooling medium passage (9). By introducing the lubricating oil flowing through the cooling medium discharge line (93) into the lubricating oil storage space (72), the temperature of the lubricating oil stored in the lubricating oil storage space (72) can be increased. By increasing the temperature of the lubricating oil stored in the lubricating oil storage space (72), the viscosity of the lubricating oil can be reduced, and mechanical loss of the equipment (e.g., bearing 22) to which the lubricating oil is supplied can be reduced.

[0088] 7) In some embodiments, the turbocharger (2) according to any one of 2) to 4) above comprises: a bearing stand (7) configured to accommodate a bearing (22) that rotatably supports a rotating shaft (21) attached to one side of the turbine rotor blade (3) in the axial direction, and having a lubricant oil storage space (72) formed therein that is configured to store lubricant oil; a lubricant oil storage device (101) provided outside the bearing stand (7) and configured to store lubricant oil; a lubricant oil introduction line (102) for guiding the lubricant oil from the lubricant oil storage device (101) to the lubricant oil storage space (72); and a cooling medium discharge line (93) for guiding the cooling medium discharged from the cooling medium passage (9), wherein the cooling medium discharge line (93) is connected to the lubricant oil storage device (101).

[0089] According to the configuration of 7) above, the lubricating oil (cooling medium) flowing through the cooling medium discharge line (93) is introduced into the lubricating oil storage device (101). By discharging the cooling medium that has flowed through the cooling medium passage (9) not into the lubricating oil storage space (72) formed inside the bearing pedestal (7) but into the lubricating oil storage device (101) provided outside the bearing pedestal (7), the structures of the cooling medium discharge line (93) and the bearing pedestal (7) can be simplified.

[0090] 8) In some embodiments, in the turbocharger (2) described in 1), the cooling medium is cooling water.

[0091] According to the configuration of 8), by using cooling water that may be used to cool the turbocharger (2) or the internal combustion engine (11) equipped with the turbocharger (2) for cooling the stationary member (8), it is possible to suppress the structure of the internal combustion engine system (1) including the turbocharger (2) from becoming complicated.

[0092] 9) In some embodiments, the turbocharger (2) according to 8) above includes: a cooling water storage device (201) configured to store cooling water; and a cooling water introduction line (202) for introducing the cooling water from the cooling water storage device (201) to the internal combustion engine (11), and the cooling medium introduction line (92) is connected to the cooling water introduction line (202).

[0093] According to the configuration of 9), the cooling water stored in the cooling water storage device (201) can be introduced into the cooling medium passage (9) via the cooling medium introduction line (92) and a portion of the cooling water introduction line (202) upstream of the connection portion with the cooling medium introduction line (92). This allows the cooling water to be used to cool the stationary member (8) while suppressing the complexity of the structure of the internal combustion engine system (1) including the turbocharger (2).

[0094] 10) In some embodiments, the turbocharger (2) according to 8) or 9) above comprises: a bearing stand (7) configured to accommodate a bearing (22) that rotatably supports a rotating shaft (21) attached to one side of the turbine rotor blades (3) in an axial direction, and having a lubricant oil storage space (72) formed therein that is configured to store lubricant oil; a lubricant oil storage device (101) provided outside the bearing stand (7) and configured to store lubricant oil; a lubricant oil introduction line (102) for guiding the lubricant oil from the lubricant oil storage device (101) to the lubricant oil storage space (72); and a cooling medium discharge line (93) for guiding the cooling medium discharged from the cooling medium passage (9), wherein the cooling medium discharge line (93) includes a heat exchange unit (98) configured to exchange heat between the lubricant oil stored in the lubricant oil storage space (72) and the cooling water flowing through the cooling medium discharge line (93).

[0095] According to the configuration of 10), the cooling water (cooling medium) flowing through the cooling medium discharge line (93) recovers thermal energy from the stationary member (8) in the cooling medium passage (9). The thermal energy recovered from the stationary member (8) is transferred to the lubricating oil stored in the lubricating oil storage space (72) through heat exchange in the heat exchange unit (98), thereby raising the temperature of the lubricating oil stored in the lubricating oil storage space (72). By raising the temperature of the lubricating oil stored in the lubricating oil storage space (72), the viscosity of the lubricating oil can be reduced, thereby reducing mechanical loss in equipment (e.g., bearings 22) to which the lubricating oil is supplied.

[0096] 11) In some embodiments, in the turbocharger (2) described in 1), the cooling medium introduction line (92) is connected to a space (impeller back space 67) formed on the back surface (43) side of the impeller (4) of the turbocharger (2).

[0097] According to the configuration of 11), the gas that has entered the space (impeller rear space 67) formed on the rear surface (43) side of the impeller (4) of the turbocharger (2) can be used to cool the stationary member (8).

[0098] 12) In some embodiments, in the turbocharger (2) according to any one of 1) to 11), the cooling medium passage (9) includes an annular pipe (cooling pipe 91) extending along the circumferential direction of the turbocharger (2).

[0099] According to the configuration of 12) above, the stationary member (8) can be cooled over a wide range in the circumferential direction of the turbocharger (2) by the cooling medium flowing through the inner space (90) of the annular pipe (91).

[0100] 13) In some embodiments, in the turbocharger (2) described in 12), the cooling medium passage (9) further includes at least one protrusion (913, 914) protruding from an inner surface (911, 912) of the annular pipe (91) and having a wall surface extending along a direction intersecting the circumferential direction of the turbocharger (2).

[0101] According to the configuration of 13), by providing the protrusions (913, 914) on the inner surface (911, 912) of the annular pipe (91), the amount of heat transferred from the cooling medium flowing inside the annular pipe (91) to the annular pipe (91) can be increased, and therefore the amount of heat recovered by the cooling medium from the stationary member (8) can be increased.

[0102] 14) In some embodiments, in the turbocharger (2) according to any one of 1) to 11), the cooling medium passage (9) includes: a first long pipe portion (915) extending along the axial direction of the turbocharger (2); a second long pipe portion (916) extending along the axial direction; a third long pipe portion (917) extending along the axial direction, the third long pipe portion (917) being disposed between the first long pipe portion (915) and the third long pipe portion (917) in the circumferential direction of the turbocharger (2), with the second long pipe portion (916) sandwiched between the third long pipe portion (917) and the first long pipe portion (915) in the circumferential direction of the turbocharger (2); and a first curved pipe portion (918) connecting one end of the first long pipe portion (915) in the axial direction and one end of the second long pipe portion (916) in the axial direction. and a second curved pipe portion (919) that connects the other axial end of the second long pipe portion (916) to the other axial end of the third long pipe portion (917).

[0103] According to the configuration of 14), the cooling medium passage (9) is formed in a so-called S-shape including the first long pipe portion (915), the second long pipe portion (916), the third long pipe portion (917), the first bent pipe portion (918), and the second bent pipe portion (919), thereby making it possible to increase the heat transfer area and the heat transfer amount. By increasing the heat transfer amount of the cooling medium passage (9), it is possible to increase the amount of heat recovered by the cooling medium from the stationary member (8).

[0104] 15) In some embodiments, in the turbocharger (2) according to any one of 1) to 14), the cooling medium passage (9) is arranged on the outer circumferential side of the cylindrical portion (81) and at an axial position corresponding to the turbine rotor blade (3).

[0105] According to the configuration of 15) above, the axial position of the cylindrical portion (81) corresponding to the turbine rotor blade (3) is a position that has a relatively large effect on the tip clearance of the turbine rotor blade (3), and by cooling this position with a cooling medium, it is possible to effectively suppress an increase in the tip clearance of the turbine rotor blade (3) during low load operation.

[0106] 16) In some embodiments, in the turbocharger (2) according to any one of 1) to 14) above, the stationary member (8) further includes a support arm portion (85) extending radially outward from an inner peripheral end portion (851) connected to the cylindrical portion (81) and having an outer peripheral end portion (852) supported by a casing (23) of the turbocharger (2), and the cooling medium passage (9) is disposed in contact with the support arm portion (85).

[0107] According to the configuration of 16), the support arm portion (85) experiences thermal expansion in the radial direction due to heat transfer from the exhaust gas, which has a relatively large effect on the tip clearance of the turbine rotor blade (3). By cooling the support arm portion (85) with a cooling medium, it is possible to effectively suppress an increase in the tip clearance of the turbine rotor blade (3) during low load operation.

[0108] REFERENCE SIGNS LIST 1 Internal combustion engine system 11 Internal combustion engine 2 Turbocharger 21 Rotating shaft 22 Bearing 23 Casing 3 Turbine rotor blade 4 Impeller 5 Turbine housing 51 Inlet side housing 52 Outlet side housing 6 Compressor housing 67 Impeller back space 7 Bearing base 8 Stationary member 9 Cooling medium passage

Claims

1. A turbocharger comprising: a turbine rotor blade configured to be driven by exhaust gas discharged from an internal combustion engine; a stationary member having a stationary wall surface facing the turbine rotor blade with a radial gap therebetween, the stationary member including a cylindrical portion forming an outlet flow path therein through which the exhaust gas that has passed through the turbine rotor blade flows; a cooling medium passage provided adjacent to the stationary member and through which a cooling medium for cooling the stationary member can flow; a cooling medium introduction line for introducing the cooling medium to the cooling medium passage; and a cooling medium flow control device configured to be able to adjust the flow rate of the cooling medium introduced to the cooling medium passage via the cooling medium introduction line, the cooling medium flow control device being configured to increase the flow rate of the cooling medium introduced to the cooling medium passage when the internal combustion engine is under low load compared to when the internal combustion engine is under high load.

2. The turbocharger according to claim 1, wherein the cooling medium is lubricating oil.

3. A turbocharger according to claim 2, comprising: a bearing stand configured to house a bearing that rotatably supports a rotating shaft attached to one axial side of the turbine rotor blades, and having a lubricant oil storage space formed therein configured to store lubricant oil; a lubricant oil storage device provided outside the bearing stand and configured to store lubricant oil; and a lubricant oil introduction line for guiding the lubricant oil from the lubricant oil storage device to the lubricant oil storage space, wherein the cooling medium introduction line is connected to the lubricant oil introduction line.

4. A turbocharger according to claim 2, wherein the turbine rotor blades are configured to house bearings that rotatably support a rotating shaft attached to one side in the axial direction, and the bearing base is provided with a lubricating oil storage space formed therein that is configured to store lubricating oil, and the cooling medium introduction line is connected to the lubricating oil storage space.

5. A turbocharger according to any one of claims 2 to 4, comprising: a bearing pedestal configured to house a bearing that rotatably supports a rotating shaft attached to one side of the turbine rotor blades in the axial direction, and having a lubricating oil storage space formed therein that is configured to store lubricating oil; a lubricating oil storage device provided outside the bearing pedestal and configured to store lubricating oil; a lubricating oil introduction line for guiding the lubricating oil from the lubricating oil storage device to the lubricating oil storage space; and a cooling medium discharge line for guiding the cooling medium discharged from the cooling medium passage, wherein the cooling medium discharge line includes a heat exchange section configured to exchange heat between the lubricating oil stored in the lubricating oil storage space and the lubricating oil flowing through the cooling medium discharge line.

6. A turbocharger according to any one of claims 2 to 4, comprising: a bearing pedestal configured to house a bearing that rotatably supports a rotating shaft attached to one side of the turbine rotor blade in the axial direction, and having a lubricating oil storage space formed therein that is configured to store lubricating oil; a lubricating oil storage device provided outside the bearing pedestal and configured to store lubricating oil; a lubricating oil introduction line for guiding the lubricating oil from the lubricating oil storage device to the lubricating oil storage space; and a cooling medium discharge line for guiding the cooling medium discharged from the cooling medium passage, wherein the cooling medium discharge line is connected to the lubricating oil storage space.

7. A turbocharger according to any one of claims 2 to 4, comprising: a bearing pedestal configured to house a bearing that rotatably supports a rotating shaft attached to one side of the turbine rotor blade in the axial direction, and having a lubricating oil storage space formed therein that is configured to store lubricating oil; a lubricating oil storage device provided outside the bearing pedestal and configured to store lubricating oil; a lubricating oil introduction line for guiding the lubricating oil from the lubricating oil storage device to the lubricating oil storage space; and a cooling medium discharge line for guiding the cooling medium discharged from the cooling medium passage, wherein the cooling medium discharge line is connected to the lubricating oil storage device.

8. The turbocharger according to claim 1, wherein the cooling medium is cooling water.

9. A turbocharger according to claim 8, comprising: a cooling water storage device configured to store cooling water; and a cooling water introduction line for guiding the cooling water from the cooling water storage device to the internal combustion engine, wherein the cooling medium introduction line is connected to the cooling water introduction line.

10. A turbocharger according to claim 8 or 9, comprising: a bearing stand configured to house a bearing that rotatably supports a rotating shaft attached to one side of the turbine rotor blades in the axial direction, and having a lubricating oil storage space formed therein configured to store lubricating oil; a lubricating oil storage device provided outside the bearing stand and configured to store lubricating oil; a lubricating oil introduction line for guiding the lubricating oil from the lubricating oil storage device to the lubricating oil storage space; and a cooling medium discharge line for guiding the cooling medium discharged from the cooling medium passage, wherein the cooling medium discharge line includes a heat exchange section configured to exchange heat between the lubricating oil stored in the lubricating oil storage space and the cooling water flowing through the cooling medium discharge line.

11. The turbocharger according to claim 1, wherein the cooling medium introduction line is connected to a space formed on the rear side of the impeller of the turbocharger.

12. A turbocharger according to any one of claims 1 to 4, 8, 9 or 11, wherein the cooling medium passage includes an annular pipe extending along the circumferential direction of the turbocharger.

13. The supercharger according to claim 12, wherein the cooling medium passage further includes at least one protruding portion that protrudes from the inner surface of the annular pipe and has a wall surface that extends along a direction intersecting the circumferential direction of the supercharger.

14. A turbocharger according to any one of claims 1 to 4, 8, 9 or 11, wherein the cooling medium passage includes: a first long pipe section extending along the axial direction of the turbocharger; a second long pipe section extending along the axial direction; a third long pipe section extending along the axial direction, the third long pipe section being disposed between the first long pipe section and the second long pipe section in the circumferential direction of the turbocharger, a first curved pipe section connecting an end of the first long pipe section on one side in the axial direction to an end of the second long pipe section on one side in the axial direction; and a second curved pipe section connecting an end of the second long pipe section on the other side in the axial direction to an end of the third long pipe section on the other side in the axial direction.

15. A turbocharger according to any one of claims 1 to 4, 8, 9 or 11, wherein the cooling medium passage is arranged on the outer circumferential side of the cylindrical portion and at an axial position corresponding to the turbine rotor blades.

16. A turbocharger according to any one of claims 1 to 4, 8, 9 or 11, wherein the stationary member further includes a support arm portion that extends radially outward from an inner peripheral end portion connected to the cylindrical portion and has an outer peripheral end portion supported by a casing of the turbocharger, and the cooling medium passage is disposed in contact with the support arm portion.

Images