Turbocharger

Abstract

To provide a turbocharger capable of securing cooling after the circulation of cooling water is stopped.SOLUTION: In the 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 pipe passage 14 for supplying cooling water to the first cooling water passage 13 is provided, the first cooling water passage 13 and the second cooling water passage 15 are connected by a communication passage 16, and a connection place of the communication passage 16 to the first cooling water passage 13 is set at a position higher than a connection place of the communication passage 16 to the second cooling water passage 15 in a vertical direction. An outflow pipe line 17 for allowing cooling water to flow out from the second cooling water passage 15 is provided so as to extend upward in the vertical direction from the second cooling water passage 15.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a turbocharger, and more particularly to a water-cooling structure for a bearing portion. [Background technology]

[0002] Because turbochargers compress intake air using the energy of the exhaust gas from an internal combustion engine, they are heated by the heat of the exhaust gas and by the heat generated by the air compression. Like ordinary mechanical components, turbochargers have a limited heat resistance, so cooling is essential. Cooling is also desirable to reduce the density of the intake air. Conventionally, a cooling water passage is formed inside the bearing housing to water-cool the bearings, seal rings, and other components. Alternatively, a cooling water passage is formed inside the compressor housing, or a water jacket is provided on the compressor housing to water-cool the compressor and compressed air. For example, in the turbocharger described in Patent Document 1, a cooling water passage provided on the turbine side inside the bearing housing is extended to the compressor side, thereby water-cooling the compressor side as well as the turbine side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-119500 A Summary of the Invention [Problem to be solved by the invention]

[0004] In some cases, the internal combustion engine (engine) equipped with a turbocharger is water-cooled. In such cases, it is preferable to circulate cooling water to the turbocharger using part of the engine's water-cooling structure. This structure eliminates the need for a turbocharger water pump and a motor for driving it. However, in hybrid vehicles (HEVs, PHEVs), the internal combustion engine stops when the vehicle is running on its own motor, or when the vehicle is stopped at a traffic light in vehicles equipped with a system that shuts down the internal combustion engine while stationary. This also shuts down the turbocharger, thereby stopping the circulation of cooling water to the turbocharger. When the internal combustion engine shuts down, the turbocharger also shuts down, eliminating heat input from the exhaust gas and heat generated by air compression. However, the turbocharger's large thermal capacity causes the turbocharger's temperature to rise. Conventionally, adequate measures have not been taken to prevent this temperature rise (dead soak: D / S) when the turbocharger is shut down, resulting in problems such as thermal degradation of the turbine seal ring and reduced durability.

[0005] The present invention has been made in view of the above technical problems, and has an object to provide a turbocharger that can ensure cooling even after the circulation of cooling water stops. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides a turbocharger comprising a compressor housing that accommodates a compressor wheel, a bearing housing that rotatably holds a shaft to which the compressor wheel is attached at one end, and a turbine housing that accommodates a turbine wheel attached to 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, and wherein an inlet pipe is provided to supply cooling water to the first cooling water passage, the first cooling water passage and the second cooling water passage are connected by a communicating passage, the connection point of the communicating passage to the first cooling water passage is set at a vertically higher position than the connection point of the communicating passage to the second cooling water passage, and an outlet pipe is provided that extends vertically upward from the second cooling water passage to discharge cooling water from the second cooling water passage. [Effects of the Invention]

[0007] In the present invention, cooling water is supplied to a first cooling water passage in a compressor housing through an inlet pipe, then supplied to a second cooling water passage through a connecting passage, and then discharged from a discharge pipe connected to the second cooling water passage. If the supply or flow of cooling water is stopped while the turbocharger temperature is high, the temperature of the cooling water rises due to the heat of the turbocharger. The amount of heat is particularly high on the turbine side through which high-temperature exhaust gas flows, causing the cooling water to evaporate inside the second cooling water passage. This causes the cooling water to absorb latent heat from the surroundings of the second cooling water passage, thereby continuously cooling the surroundings of the second cooling water passage, as well as the turbine housing and bearing housing. The cooling water vapor flows upward through the discharge pipe and connecting passage extending above the second cooling water passage, releasing latent heat to the outside and condensing in the process. The liquefied cooling water flows down inside the discharge pipe and connecting passage toward the second cooling water passage. The cooling water then evaporates again due to the heat of the bearing housing and the compressor housing. In other words, even if the supply or circulation of the cooling water is stopped, the cooling water remaining in the second cooling water passage continues to circulate as it evaporates and condenses, so the turbocharger can continue to be cooled. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram conceptually illustrating an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Next, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the embodiment described below is merely an example of how the present invention can be implemented, and is not intended to limit the present invention.

[0010] Fig. 1 is a schematic diagram conceptually illustrating an embodiment of the present invention. The turbocharger T / C shown here is installed in the exhaust pipe of an internal combustion engine E, which is the driving force source for a vehicle, and its basic function and structure are almost the same as those of conventionally known turbochargers. To briefly explain the configuration, a compressor wheel 2 is installed at one end of a turbine shaft 1, and a turbine wheel 3 is installed at the other end. This turbine shaft 1 passes through a bearing housing 4 and is rotatably supported by bearings 5 ​​installed inside the bearing housing 4.

[0011] A compressor housing 6 that houses the compressor wheel 2 is attached in close contact with one side of the bearing housing 4. The compressor housing 6 has an intake port 7 that extends on the same axis as the compressor wheel 2. In addition, a spiral air flow path 8 is formed on the outer periphery of the compressor wheel 2, and the cross-sectional area of ​​the air flow path 8 gradually decreases towards the tip.

[0012] A turbine housing 9, which houses the turbine wheel 3, is attached in close contact with the other side of the bearing housing 4. The turbine housing 9 has a spiral exhaust passage 10 formed on the outer periphery of the turbine wheel 3, which gradually reduces in cross-sectional area at the tip end (toward the center of the turbine housing 9) so that exhaust from an internal combustion engine E (not shown) can be blown onto the turbine wheel 3. In the example shown in FIG. 1, two exhaust passages 10 are formed. Furthermore, the turbine housing 9 is provided with an exhaust port 11 that houses the turbine wheel 3 and extends out on the same axis as the turbine wheel 3.

[0013] A seal ring 12 is fitted onto the end of the turbine shaft 1 on the turbine wheel 3 side. This seal ring 12 tightly contacts the inner peripheral surface of the bearing housing 4, thereby airtightly sealing the space between the inside of the turbine housing 9 and the portion of the bearing housing 4 where the bearing 5 is provided.

[0014] Next, the water-cooling structure will be described. A first cooling water passage 13 is formed inside the above-mentioned compressor housing 6. The first cooling water passage 13 is a void space opened inside the compressor housing 6, and in the example shown in Fig. 1, is formed in an annular shape so as to surround the outer periphery of the compressor wheel 2. An inlet pipe 14 is connected to this first cooling water passage 13, and cooling water is supplied from the inlet pipe 14.

[0015] A second cooling water passage 15 is formed inside the bearing housing 4. The second cooling water passage 15 is a void space formed inside the bearing housing 4, and in the example shown in Fig. 1, is formed in an annular shape so as to surround the outer periphery of the seal ring 12 described above.

[0016] A communication passage 16 is provided to connect the first cooling water passage 13 and the second cooling water passage 15 in series. The communication passage 16 may be a conduit that passes through the inside of the compressor housing 6 or the bearing housing 4, or may be a pipe attached to the outside of these housings 4, 6. The connection point of this communication passage 16 to the first cooling water passage 13 is set at a higher position in the vertical direction than the connection point to the second cooling water passage 15. This is to allow the cooling water to flow down from the first cooling water passage 13 toward the second cooling water passage 15.

[0017] Furthermore, an outflow pipe 17 is connected to the second cooling water passage 15. The outflow pipe 17 is a pipe for returning the cooling water from the second cooling water passage 15 to the outside, and therefore at least a portion of it is formed by a pipe connected to the outside of the bearing housing 4, and extends upward from the second cooling water passage 15. The outflow pipe 17 is then connected to a pump P driven by the internal combustion engine E. Furthermore, a heat radiator R such as a radiator is connected to the pump P, and the inflow pipe 14 described above is connected to the heat radiator R.

[0018] When the internal combustion engine E is operating, its exhaust gas is blown through the exhaust passage 10 onto the turbine wheel 3, causing the turbine wheel 3 to rotate, which in turn rotates the compressor wheel 2 integral with the turbine wheel 3. As a result, air is drawn in through the intake port 7, and the air is compressed and pressurized as it flows through the air passage 8, and is then supplied to the internal combustion engine E as intake air.

[0019] When the internal combustion engine E is operating, the pump P rotates and causes the cooling water to flow. The cooling water, whose temperature has been reduced in the radiator R, is first supplied to the first cooling water passage 13. As described above, the first cooling water passage 13 is provided in a state in which it surrounds the outer periphery of the compressor wheel 2, and therefore absorbs heat from the compressed and heated air and the compressor housing 6, which has been warmed by that air, to cool them. The cooling water is then sent to the second cooling water passage 15 through the communication passage 16. As described above, the second cooling water passage 15 is provided inside the bearing housing 4 and surrounds the seal ring 12, and therefore the cooling water supplied to the second cooling water passage 15 absorbs heat from the bearing housing 4 and the seal ring 12 to cool them. The cooling water is then sent to the radiator R via the pump P, where it is cooled by heat radiation from the air. When the internal combustion engine E is operating, the cooling water circulates as described above, thereby cooling the turbocharger T / C and the intake air.

[0020] When the internal combustion engine E stops, the pump P stops and the coolant stops circulating. In this case, heat is no longer carried away from the turbocharger T / C, and the temperatures of the housings 4, 6, and 9 and the wheels 2 and 3 rise due to the heat they retain. Meanwhile, the coolant that has accumulated inside the second coolant passage 15, the communicating passage 16 that communicates with it, and the outlet pipe 17 is heated by the heat of the housings 4, 6, and 9 and the wheels 2 and 3, and evaporates or boils. As a result, the coolant absorbs the latent heat of evaporation, and it is possible to cool at least the turbine side portion of the bearing housing 4, the seal ring 12, and the like.

[0021] Furthermore, the cooling water vapor rises inside the outflow pipe 17 and the communication passage 16. If the outflow pipe 17 and the communication passage 16 are configured as pipes attached to the outside of the bearing housing 4 and the compressor housing 6 and exposed to the outside air, for example, so that they are cooled by the outside air, the cooling water vapor rising inside them will release latent heat and condense. The condensed cooling water then returns to the second cooling water passage 15. In other words, the cooling water carries heat to the outside as it evaporates and condenses, thereby cooling the turbine side portion of the bearing housing 4, the seal ring 12, and the like.

[0022] In conclusion, according to the embodiment of the above-described configuration, even when the cooling water does not circulate due to a temporary stop of the internal combustion engine E, it is possible to perform so-called ascites cooling by evaporation and condensation of the cooling water, thereby avoiding or suppressing excessive temperature rise (or dead soak) of the turbocharger T / C, or the resulting early deterioration or damage of the seal ring, or the decrease in durability. [Explanation of symbols]

[0023] 1 turbine shaft 2 Compressor Wheel 3 Turbine Wheel 4 Bearing housing 5. Bearings 6 Compressor housing 7 Intake port 8 Air Flow Channel 9 Turbine housing 10 Exhaust flow path 11 Exhaust port 12 Seal ring 13 First cooling water channel 14 Inflow pipe 15 Second cooling water channel 16 Communication path 17 Outflow pipe E. Internal combustion engine P pump R Heat sink T / C turbocharger

Claims

[Claim 1] A turbocharger comprising: a compressor housing accommodating a compressor wheel; a bearing housing rotatably supporting a shaft having one end to which the compressor wheel is attached; and a turbine housing accommodating a turbine wheel attached to 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, an inlet pipe for supplying cooling water to the first cooling water passage; the first cooling water passage and the second cooling water passage are connected by a communication passage, and a connection point of the communication passage to the first cooling water passage is set at a position higher in the vertical direction than a connection point of the communication passage to the second cooling water passage, An outflow pipe for discharging cooling water from the second cooling water passage is provided so as to extend vertically upward from the second cooling water passage. A turbocharger characterized by:

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