Turbocharger

Abstract

In a turbocharger (T / C) in which a first cooling water passage (13) is provided inside a compressor housing (6) and a second cooling water passage (15) is provided inside a bearing housing (4), an inflow line (14) for supplying cooling water is provided in the first cooling water passage (13), and an inflow line (15) for supplying cooling water is provided in the second cooling water passage (15). The first cooling water path (13) and the second cooling water path (15) are connected by a communication path (16), and the connection portion of the communication path (16) with respect to the first cooling water path (13) is set at a position higher in the vertical direction than the connection portion of the communication path (16) with respect to the second cooling water path (15). An outflow line (17), through which the cooling water flows out from the second cooling water path (15), is provided so as to extend upward in the vertical direction from the second cooling water path (15).

Description

Technical Field

[0001] This invention relates to turbochargers, and more particularly to a water-cooled structure for the bearing section. Background Technology

[0002] Turbochargers use the energy of the exhaust gas from an internal combustion engine to compress the intake air, thus being heated by the heat of the exhaust gas and the heat accompanying the air compression. Like ordinary mechanical components, turbochargers have limits to their heat resistance and therefore must be cooled. Furthermore, cooling is also desired to reduce the density of the intake air. Therefore, conventionally, cooling water passages are formed inside the bearing housing to water-cool the bearings, sealing rings, etc. Alternatively, cooling water passages are provided inside the compressor housing, or a water jacket is installed in the compressor housing, thereby water-cooling the compressor and the compressed air. For example, in the turbocharger described in Patent Document 1, a cooling water passage located inside the bearing housing on the turbine side extends towards the compressor side, water-cooling the compressor side along with the turbine side.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-119500 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] Sometimes, internal combustion engines (engines) equipped with turbochargers are themselves water-cooled. In such cases, it is preferable to utilize a portion of the internal combustion engine's water-cooling structure to circulate coolant within the turbocharger. With this configuration, the water pump for the turbocharger and the electric motor driving it can be omitted. However, for internal combustion engines installed in vehicles, in hybrid electric vehicles (HEVs, PHEVs) when the electric motor is running, or in vehicles equipped with systems that stop the internal combustion engine during parking when stopped due to traffic signals, the internal combustion engine stops, and therefore, the circulation of coolant relative to the turbocharger also stops. When the internal combustion engine stops, the turbocharger also stops, so the heat input from exhaust and the heat generated by air compression disappear, but the turbocharger temperature rises due to its large heat capacity. Previously, due to insufficient countermeasures against this temperature rise when the turbocharger stops (dead soak), there have been adverse conditions such as accelerated thermal degradation of the turbine-side sealing rings or reduced durability.

[0008] This invention was made in view of the above-mentioned technical problems, and its purpose is to provide a turbocharger that can ensure cooling after the circulation of cooling water stops.

[0009] Methods for solving problems

[0010] To achieve the above objectives, the turbocharger of the present invention comprises: a compressor housing housing a compressor impeller; a bearing housing housing a shaft on which the compressor impeller is mounted at one end is rotatable; and a turbine housing housing a turbine impeller mounted at the other end of the shaft. A first cooling water passage is provided inside the compressor housing, and a second cooling water passage is provided inside the bearing housing. The turbocharger is characterized in that an inflow pipe for supplying cooling water is provided in the first cooling water passage, the first cooling water passage and the second cooling water passage are connected by a connecting passage, and the connecting passage relative to the connection portion of the first cooling water passage is positioned higher in the vertical direction than the connection portion of the connecting passage relative to the second cooling water passage. An outflow pipe from which cooling water flows out of the second cooling water passage is provided such that it extends upward in the vertical direction from the second cooling water passage.

[0011] Invention Effects

[0012] In this invention, cooling water is supplied to a first cooling water passage within the compressor housing via an inlet pipe, and from there to a second cooling water passage via a connecting passage, and then discharged from a discharge pipe connected to the second cooling water passage. When the supply or flow of cooling water stops due to the high temperature of the turbocharger, the temperature of the cooling water rises due to the heat generated by the turbocharger. In particular, the turbine side, where the high-temperature exhaust flows, has high heat, causing the cooling water to evaporate inside the second cooling water passage. Therefore, the cooling water absorbs latent heat of vaporization from the surroundings of the second cooling water passage, thus the area around the second cooling water passage, or the turbine housing and bearing housing, continues to be cooled. The vapor of the cooling water becomes an upward flow and flows from the second cooling water passage through the interior of the discharge pipe and connecting passage extending upwards, releasing latent heat and condensing in the process. The liquefied cooling water flows downwards towards the second cooling water passage inside the discharge pipe and connecting passage. Furthermore, it evaporates again due to the heat of the bearing housing and compressor housing. That is, even if the supply or circulation of cooling water stops, the cooling water remaining in the second cooling water circuit will continue to circulate along with evaporation and condensation, thus continuing to cool the turbocharger. Attached Figure Description

[0013] Figure 1 This is a schematic diagram that conceptually represents an embodiment of the present invention.

[0014] Explanation of reference numerals in the attached figures

[0015] 1 turbine shaft

[0016] 2 Compressor Impeller

[0017] 3 turbine impellers

[0018] 4 Bearing Housing

[0019] 5 bearings

[0020] 6 Compressor housing

[0021] 7 suction port

[0022] 8 airflow paths

[0023] 9 Turbine housing

[0024] 10 Exhaust Flow Path

[0025] 11 exhaust ports

[0026] 12 sealing rings

[0027] 13 First Cooling Water Circuit

[0028] 14 Inflow Pipeline

[0029] 15 Second Cooling Water Circuit

[0030] 16 connecting paths

[0031] 17 Outflow pipe

[0032] E internal combustion engine

[0033] P pump

[0034] R Heatsink

[0035] T / C turbocharger. Detailed Implementation

[0036] Next, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the embodiments described below are merely examples of implementing the present invention and do not limit the present invention.

[0037] Figure 1 This is a schematic diagram conceptually illustrating an embodiment of the invention. The turbocharger T / C shown here is installed in the exhaust pipe of the internal combustion engine E, which serves as the driving force source for the vehicle. Its basic function and construction are largely the same as conventionally known turbochargers. To briefly describe its structure, a compressor impeller 2 is provided at one end of the turbine shaft 1, and a turbine impeller 3 is provided at the other end. The turbine shaft 1 passes through a bearing housing 4 and is held rotatably by a bearing 5 located inside the bearing housing 4.

[0038] The compressor housing 6, which houses the compressor impeller 2, is mounted in a state of close contact with one side of the bearing housing 4. The compressor housing 6 has an intake port 7 extending along the same axis as the compressor impeller 2. In addition, a vortex-shaped airflow path 8 is formed on the outer periphery of the compressor impeller 2, with the cross-sectional area gradually decreasing at the tip.

[0039] Additionally, on the other side of the bearing housing 4, a turbine housing 9, which houses the turbine impeller 3, is mounted in close contact with it. In the turbine housing 9, in order to blow exhaust gas from the internal combustion engine E (not shown) towards the turbine impeller 3, a vortex-shaped exhaust flow path 10 is formed on the outer periphery of the turbine impeller 3, with a gradually decreasing cross-sectional area at its apex (the center side of the turbine housing 9). It should be noted that... Figure 1 In the example shown, two exhaust flow paths 10 are formed. Furthermore, an exhaust port 11 that houses the turbine impeller 3 and extends along the same axis as the turbine impeller 3 is provided in the turbine housing 9.

[0040] Furthermore, a sealing ring 12 is embedded at the end of the turbine shaft 1 on the turbine impeller 3 side. The sealing ring 12 is in close contact with the inner circumferential surface of the bearing housing 4, thereby sealing the interior of the turbine housing 9 and the part of the bearing housing 4 where the bearing 5 is located in an airtight state.

[0041] Next, the structure for water cooling will be described. A first cooling water passage 13 is formed inside the compressor housing 6. The first cooling water passage 13 is a space opened inside the compressor housing 6. Figure 1 In the example shown, the impeller 2 is formed in a ring shape surrounding its outer periphery. An inflow pipe 14 is connected to the first cooling water passage 13, and cooling water is supplied from the inflow pipe 14 to the first cooling water passage 13.

[0042] Furthermore, a second cooling water passage 15 is formed inside the bearing housing 4. The second cooling water passage 15 is a space created inside the bearing housing 4. Figure 1 In the example shown, it is formed in a ring shape to surround the outer periphery of the aforementioned sealing ring 12.

[0043] A connecting passage 16 is provided to connect the first cooling water passage 13 and the second cooling water passage 15 in series. The connecting passage 16 can be a pipe that passes through the interior of the compressor housing 6 and the bearing housing 4, or it can be a pipe installed on the exterior of these housings 4 and 6. The connection point of the connecting passage 16 relative to the first cooling water passage 13 is positioned higher in the vertical direction than the connection point relative to the second cooling water passage 15. This is to allow cooling water to flow from the first cooling water passage 13 to the second cooling water passage 15.

[0044] Furthermore, the outflow pipe 17 is connected to the second cooling water passage 15. The outflow pipe 17 is a pipe for returning cooling water from the second cooling water passage 15 to the outside; therefore, at least a portion of it is composed of a pipe connected to the outside of the bearing housing 4, extending upwards from the second cooling water passage 15. The outflow pipe 17 is also connected to a pump P driven by the internal combustion engine E. Additionally, a radiator R, such as a radiator, is connected to the pump P, and the aforementioned inflow pipe 14 is connected to the radiator R.

[0045] When the internal combustion engine E is running, its exhaust gas is blown to the turbine impeller 3 through the exhaust flow path 10, causing the turbine impeller 3 to rotate, and the compressor impeller 2 integrated with it to rotate. As a result, air is drawn in from the intake port 7, and the air is pressurized and compressed as it flows in the air flow path 8, and supplied to the internal combustion engine E as intake air.

[0046] With the internal combustion engine E running, pump P rotates, causing cooling water to flow. The cooled water, now cooled in the radiator R, is first supplied to the first cooling water passage 13. As described above, the first cooling water passage 13 is configured to surround the outer periphery of the compressor impeller 2, thus drawing heat from the compressed, heated air and the compressor housing 6, cooling them. This cooling water is then supplied to the second cooling water passage 15 via the connecting passage 16. As described above, the second cooling water passage 15 is configured inside the bearing housing 4, surrounding the sealing ring 12, thus the cooling water supplied to the second cooling water passage 15 draws heat from the bearing housing 4 and the sealing ring 12, cooling them. Afterward, the cooling water is pumped by pump P to the radiator R, where it is cooled by air dissipation. With the internal combustion engine E running, the cooling water circulates as described above, thus cooling the turbocharger T / C and the intake air.

[0047] When the internal combustion engine E stops, the pump P stops, and therefore the cooling water does not circulate. In this case, since heat is not removed from the turbocharger T / C, the temperatures of the housings 4, 6, 9, impellers 2, 3, etc., rise due to the heat they possess. On the other hand, the cooling water accumulated inside the second cooling water passage 15, the connecting passage 16 connected to it, and the outflow pipe 17 is heated by the heat possessed by the housings 4, 6, 9, impellers 2, 3, etc., and thus evaporates or boils. Along with this, the cooling water absorbs the latent heat of vaporization, thus at least cooling the turbine side portion of the bearing housing 4, the sealing ring 12, etc.

[0048] Furthermore, the cooling water vapor rises inside the outlet pipe 17 and the connecting passage 16. If these outlet pipes 17 and the connecting passage 16 are structures made of pipes installed outside the bearing housing 4 and the compressor housing 6, and are exposed to external gases and cooled by them, the cooling water vapor rising inside them releases latent heat and condenses. Then, the condensed cooling water returns to the second cooling water passage 15. That is, the cooling water transports heat to the outside through evaporation and condensation, thus cooling the turbine side portion of the bearing housing 4, the sealing ring 12, etc.

[0049] As a result, according to the above-described implementation, even when the cooling water does not circulate due to the temporary shutdown of the internal combustion engine E, so-called basal water cooling based on the evaporation and condensation of the cooling water can be performed. Therefore, excessive temperature rise (or shutdown temperature rise) of the turbocharger T / C, or the premature deterioration or damage of the sealing rings, or the reduction in durability that may accompany it, can be avoided or suppressed.

Claims

1. A turbocharger comprising: a compressor housing housing a compressor impeller; a bearing housing holding a shaft with the compressor impeller mounted at one end rotatable; and a turbine housing housing a turbine impeller mounted at the other end of the shaft, wherein a first cooling water passage is provided inside the compressor housing, and a second cooling water passage is provided inside the bearing housing, characterized in that... An inflow pipe for supplying cooling water is provided in the first cooling water circuit. The first cooling water passage and the second cooling water passage are connected by a connecting passage, and the connecting passage is positioned at a higher position in the vertical direction compared to the connection point of the first cooling water passage and the connection point of the connecting passage relative to the second cooling water passage. The outlet pipe that allows cooling water to flow out of the second cooling water path is provided in a manner that extends upward in the vertical direction from the second cooling water path.

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