JP2009270468A - Cooling system of turbosupercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling system simply structured to cool a turbine house. <P>SOLUTION: Exhaust air from an internal combustion engine 13 is supplied to a turbine 12T of a high-pressure-stage turbosupercharger 12 via a first exhaust passage 14. An outlet port of the turbine 12T is coupled to an inlet port of a turbine 11T of a low-pressure-stage turbosupercharger 11 via a second exhaust passage 15. A third exhaust passage 16 is couple to the outlet port of the turbine 12T. A cooling passage 24 is provided which makes the second and third exhaust passages 15, 16 communicate with each other. A route of the cooling passage 24 is allowed to go through a turbine housing of the turbine 12T to absorb heat of the turbine housing by means of exhaust air flowing from the second exhaust passage 15 to the third exhaust passage 16. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cooling system for a turbine housing in a turbocharger.

  In a turbocharger that uses exhaust energy to supercharge an internal combustion engine, high-temperature combustion gas is supplied from the exhaust manifold to the turbine, so the turbine becomes extremely hot. Further, in a supercharging system in which a plurality of turbochargers are provided in multiple stages, the temperature rise becomes significant particularly in a high-pressure turbine that receives supply of exhaust gas directly from an exhaust manifold (see Patent Document 1). For this reason, heat resistant steel is generally used for the turbine housing to ensure heat resistance.

On the other hand, in a turbocharger with an electric motor, the permanent magnet of the electric motor may be demagnetized when the turbine stops in a high temperature state. For this reason, in order to prevent demagnetization of the permanent magnet in the electric turbocharger, a configuration has been proposed in which a cooling passage for flowing a cooling medium is provided in the turbine housing and the cooling medium is supplied to the cooling passage (Patent Document). 2).
JP 2007-138798 A JP 2004-084480 A

  As described above, in the turbocharger with an electric motor, a configuration in which a cooling mechanism is provided in the turbo housing for the purpose of preventing demagnetization of the permanent magnet in the electric motor has been proposed. However, in a general turbocharger, a special cooling is provided. Heat resistance is ensured by using heat-resistant steel without providing a mechanism. On the other hand, since heat-resistant steel is expensive, if a material with low high-temperature strength can be used, the cost of the turbocharger can be significantly reduced. However, in the configuration as disclosed in Patent Document 2, a separate power unit for supplying a cooling medium, a mechanism for connecting the power unit and the cooling passage, and the like are required, which increases the size and weight of the unit. At the same time, the cost may increase, and there is a possibility that the benefit of cost reduction by changing the material cannot be obtained.

  An object of this invention is to provide the cooling system which cools a turbine housing by simple structure.

  A turbocharger cooling system according to the present invention includes a first turbine driven by exhaust from an internal combustion engine, a turbine housing that houses the first turbine, an exhaust passage connected to a downstream side of the first turbine, A pressure loss generating element that is provided on the exhaust passage and generates a predetermined pressure loss communicates with an upstream side and a downstream side of the pressure loss generating element of the exhaust passage, and exhaust gas in the exhaust passage is from upstream to downstream. And a cooling passage that circulates, the cooling passage passes through the turbine housing, and the exhaust absorbs heat of the turbine housing.

  The connection portion of the cooling passage on the downstream side of the pressure loss generating element with the exhaust passage is preferably arranged on the upstream side of the exhaust catalyst. As a result, the exhaust gas whose temperature has risen again due to heat absorption in the turbine housing is supplied to the exhaust catalyst, the purification efficiency of the catalyst is improved, and emission is improved.

  Further, for example, the cooling system is used in a supercharging system including a plurality of turbine superchargers, a second turbine is connected to the downstream side of the first turbine, and the second turbine can be used as the pressure loss generating element. It is. Alternatively, the second turbine is connected to the downstream side of the first turbine, the pressure loss generating element is provided on the downstream side of the second turbine, and the connection portion on the upstream side of the pressure loss generating element in the cooling passage is downstream of the second turbine. Placed on the side. Thereby, the exhaust gas whose temperature is further lowered can be used for cooling the first turbine, and the cooling efficiency can be improved.

  When the pressure loss generating element is provided on the downstream side of the second turbine, the pressure loss generating element is, for example, an exhaust throttle valve or an upstream exhaust catalyst among a plurality of exhaust catalysts connected in series to the exhaust passage.

  When the exhaust throttle valve is used as the above pressure loss generating element, an exhaust throttle valve bypass passage that communicates the upstream side and the downstream side of the exhaust throttle valve is provided, and the upstream pressure in the exhaust throttle valve bypass passage is lower than the downstream pressure. It is preferable to provide a reverse valve that opens only when the pressure exceeds a predetermined pressure. This can prevent the upstream pressure of the exhaust throttle valve from rising excessively.

  A cooling passage valve is provided in the cooling passage, and the difference between the pressure upstream of the pressure loss generating element and the pressure downstream of the pressure loss generating element is larger than the pressure loss between the inlet and outlet of the cooling passage. The cooling passage valve is preferably opened. Thereby, the reverse flow of the cooling passage can be prevented, and a stable exhaust flow can be created in the cooling passage.

  As described above, according to the present invention, it is possible to provide a cooling system that cools the turbine housing with a simple configuration.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of the turbocharger cooling system according to the first embodiment of the present invention.

  In the present embodiment, the turbocharger system 10 is, for example, a multistage turbocharger system. FIG. 1 shows a turbocharger in which a low-pressure stage turbocharger 11 and a high-pressure stage turbocharger 12 are connected in series. The system is shown.

  The first exhaust passage 14 connected to the exhaust manifold of the internal combustion engine 13 is connected to the inlet of the turbine 12T (first turbine) of the high-pressure turbocharger 12, and the outlet of the turbine 12T is connected to the second exhaust passage 15. To the inlet of the turbine 11T (pressure loss generating element) of the low-pressure stage turbocharger 11. A third exhaust passage 16 is connected to the outlet of the turbine 11T and communicates with the outside via an exhaust catalyst (not shown). Further, the first exhaust passage 14 and the second exhaust passage 15 are communicated by an exhaust bypass passage 17, and an exhaust switching valve 18 is provided in the exhaust bypass passage 17.

  A first intake passage 19 is connected to the inlet of the compressor 11C of the low-pressure turbine 11 and the inlet of the compressor 11C is communicated to the outside via an air cleaner (not shown). The outlet of the compressor 11C and the inlet of the compressor 12C are connected by a second intake passage 20, and the outlet of the compressor 12C and the intake manifold of the internal combustion engine 13 are connected by a third intake passage 21. The second intake passage 20 and the third intake passage 21 are communicated with each other by an intake bypass passage 22, and an intake switching valve 23 is provided in the intake bypass passage 22.

  In the turbocharging system 10 of the present embodiment, when the internal combustion engine 13 is in the low speed rotation range, the exhaust gas switching valve 18 and the intake air switching valve 23 are closed. That is, the exhaust is exhausted to the outside through the first exhaust passage 14, the turbine 12T, the second exhaust passage 15, the turbine 11T, and the exhaust passage 16, and both the turbines 11T and 12T are driven by the exhaust. As a result, the compressors 11T and 12T are operated, and the air taken in from the first intake passage 19 is pressurized by the compressor 11C and then further pressurized by the compressor 12C and supercharged to the internal combustion engine 13. . That is, in the low-speed rotation region, supercharging is performed using both the low pressure turbocharger 11 and the high pressure turbocharger 12.

  On the other hand, in the high speed range, the exhaust switching valve 18 and the intake switching valve 23 are fully opened, and almost all of the flow flows through the exhaust bypass passage 17 and the intake bypass passage 22. That is, the exhaust is discharged to the outside through the first exhaust passage 14, the exhaust bypass passage 17, the turbine 11T, and the third exhaust passage 16, and only the turbine 11T of the low-pressure turbocharger 11 is driven by the exhaust. As a result, only the compressor 11C of the low-pressure turbocharger 11 having a large turbine capacity is operated in the high-speed rotation region, and the air taken in from the first intake passage 19 is pressurized only by the compressor 11C and is injected into the internal combustion engine 13. Supercharged. That is, in the high-speed rotation region, supercharging is performed using only the low-pressure turbocharger 11. For example, in the low-speed to medium-speed rotation range, the opening degree of the exhaust gas switching valve 18 may be adjusted according to the operating state.

  In the first embodiment, a cooling passage 24 that communicates between the second exhaust passage 15 and the third exhaust passage 16 is further provided. The cooling passage 24 communicates with the third exhaust passage 16 via the turbine housing of the turbine 12T of the high-pressure turbocharger 12. A cooling passage valve 25 is provided between the turbine housing of the turbine 12T and the third exhaust passage 16.

  2 and 3 show an example of a housing passage provided in the turbine housing 12H and constituting a part of the cooling passage 24. FIG. 2 and 3 are cross-sectional views of the high-pressure turbocharger 12. As shown in FIGS. 2 and 3, a scroll 121 defined by a turbine housing 12 </ b> H is provided around the turbine wheel 120. In the turbine 12T, the housing passage is provided, for example, along the periphery of the scroll 121. In the example of FIG. 2, the periphery of the scroll 121 has a double structure, so that the space defined around the scroll 121 is a housing. Used as the inner passage 122. On the other hand, in the example of FIG. 3, a plurality of narrow passages are formed along the periphery of the scroll 121 in the turbine housing 12 </ b> H, and these are used as the in-housing passages 123.

  Next, the operation principle of the cooling system for the turbocharger in the first embodiment will be described with reference to FIG.

  As shown in FIG. 1, in the first embodiment, the cooling passage 24 includes a second exhaust passage 15 that connects the turbine 12T and the turbine 11T, and a third exhaust passage 16 that is connected to the downstream side of the turbine 11T. They are connected. Since the pressure Pe1 of the second exhaust passage 15 is higher than the pressure Pe2 of the third exhaust passage 16 connected to the downstream side of the turbine 11T, the difference between the pressure Pe1 and the pressure Pe2 (pressure loss due to the turbine 11T) is the cooling passage. If the pressure loss from the inlet (connecting portion with the second exhaust passage 15) 24 to the outlet (connecting portion with the third exhaust passage 16) is larger than the pressure loss, the exhaust in the second exhaust passage 15 passes through the cooling passage 24. And flows out to the third exhaust passage 16. That is, when the pressure loss in the cooling passage 24 (excluding the housing passage) is dPe, the pressure loss in the housing passage 122 is dPh, and the pressure loss in the cooling passage valve 25 is dPv, the condition of Pe1−Pe2> dPe + dPh + dPv is satisfied. Below, exhaust flows from the second exhaust passage 15 to the third exhaust passage 16 through the cooling passage 24.

  Therefore, in the present embodiment, for example, when the exhaust gas switching valve 18 is closed, the cooling passage valve 25 is opened under the condition that (Pe1-Pe2) is larger than (dPe + dPh + dPv). In the opening / closing control of the cooling passage valve 25, for example, values of dPe, dPh, dPv are obtained in advance, and the closed state of the exhaust switching valve 18 is monitored, and the values of Pe1, Pe2 are monitored by a pressure sensor or the like. This is performed by making the above determination in an ECU (not shown).

  Since the exhaust of the second exhaust passage 15 is exhaust through the turbine 12T, its temperature is lower than the temperature at the inlet of the turbine 12T. Therefore, the temperature of the turbine 12T can be lowered by flowing the exhaust of the second exhaust passage 15 through the housing passage 122 of the turbine housing 12H.

  As described above, according to the first embodiment, the exhaust from the second exhaust passage 15 is supplied as a refrigerant to the turbine housing 12H of the high-pressure turbocharger 12, and the heat of the housing is exhausted from the second exhaust passage 15. As a result, the turbine housing 12H can be cooled with a simple configuration without adding a separate power source. Further, since the exhaust temperature through the cooling passage 24 (housing passage) rises, the purification efficiency in the catalyst is improved by connecting the outlet of the cooling passage to the upstream side of the exhaust catalyst of the third exhaust passage 16. And emission is improved.

  Next, a second embodiment of the present invention will be described with reference to FIG. The configuration of the second embodiment is different from the first embodiment only in the configuration related to the connection position of the cooling passage. Therefore, the description of the other configurations is omitted and the same reference numerals are used for the same configurations. The same applies to other embodiments described below.

  In the turbocharger system 30 of the second embodiment, as shown in FIG. 4, an exhaust throttle valve 26 (pressure loss generating element) is provided on the third exhaust passage 16. In the second embodiment, one end of the cooling passage 27 is connected to the third exhaust passage 16 downstream of the turbine 11T of the low-pressure turbocharger 11 and upstream of the exhaust throttle valve 26, and the other end is exhausted. Connected to the downstream side of the throttle valve 26. In the example of FIG. 4, the cooling passage valve 25 is provided between the connection portion of the cooling passage 27 to the third exhaust passage 16 on the upstream side of the exhaust throttle valve 26 and the turbine 12T.

  Before and after the exhaust throttle valve 26, the pressure is reduced on the downstream side due to the pressure loss in the throttle valve. Therefore, as in the first embodiment, when the exhaust bypass valve 18 is closed, the connection with the upstream side of the exhaust throttle valve 26 is performed. The difference between the pressure Pe1 in the section and the pressure Pe2 in the connection section on the downstream side of the exhaust throttle valve 26 (pressure loss due to the exhaust throttle valve 26) is larger than the pressure loss (dPe + dPh + dPv) related to the cooling passage 24. Below, the cooling passage valve 25 is opened. Thereby, the reverse flow of the cooling passage can be prevented, and a stable exhaust flow can be created in the cooling passage.

  With the above configuration, the same effects as in the first embodiment can be obtained in the second embodiment. Further, in the second embodiment, since the exhaust through the turbine 11T of the low-pressure turbocharger 11 is used as a refrigerant, the temperature of the exhaust is lower than that of the first embodiment, and the cooling efficiency is further increased. Can do.

  Next, a third embodiment of the present invention will be described with reference to FIG. The configuration of the turbocharger system 40 of the third embodiment is such that an exhaust throttle valve bypass passage 28 that bypasses the exhaust throttle valve 26 (pressure loss generating element) is provided in the configuration of the second embodiment. On the bypass passage 28, a reversely supported valve 29 having a pressure adjusting function is provided. The reverse support valve 29 is a valve that opens only when the upstream pressure of the exhaust throttle valve 26 is higher than the downstream pressure by a predetermined value or more, and the upstream pressure of the exhaust throttle valve 26 increases excessively. To prevent. This predetermined value is larger than the pressure difference of the pressure loss (dPe + dPh + dPv) related to the cooling passage 24.

  As described above, also in the third embodiment, the same effect as in the second embodiment can be obtained, and an excessive pressure increase on the upstream side of the exhaust throttle valve 26 can be prevented.

  FIG. 6 is a block diagram illustrating a configuration of a turbocharging system and a cooling system according to a fourth embodiment of the present invention.

  In the turbocharger system 50 of the fourth embodiment, the first exhaust catalyst 31 (pressure loss generating element) and the second exhaust catalyst 32 are arranged in series on the third exhaust passage 16, and the first exhaust catalyst 31 is It is arranged upstream of the second exhaust catalyst 32. One end of the cooling passage 33 is connected to the third exhaust passage 16 on the downstream side of the turbine 11T of the low-pressure turbocharger 11 and upstream of the first exhaust catalyst 31, and the other end is connected to the first exhaust catalyst 31. And is connected to the third exhaust passage 16 on the upstream side of the second exhaust catalyst 32. Similarly to the second and third embodiments, the cooling passage valve 25 is provided between the connection portion on the upstream side of the first exhaust catalyst 31 in the cooling passage 33 and the turbine 12T.

  Before and after the first exhaust catalyst 31, the upstream pressure Pe1 is higher than the downstream pressure Pe2 due to the pressure loss in the first exhaust catalyst 31, so that the pressure Pe1 and the pressure Pe2 in the state where the exhaust switching valve 18 is closed. The cooling passage valve 25 is opened under the condition that the difference (pressure loss in the first exhaust catalyst 31) becomes larger than the pressure loss (dPe + dPh + dPv). Thereby, the exhaust gas between the turbine 11T and the first exhaust catalyst 31 is supplied as a refrigerant to the turbine 12T of the high-pressure turbocharger 12, and the turbine housing 12H is cooled.

  As described above, also in the fourth embodiment, the same effect as in the second embodiment can be obtained.

  In the present embodiment, a multistage turbocharger system has been described as an example, but a parallel twin turbo or a single turbocharger also uses a pressure difference in an exhaust passage downstream of the turbine, The cooling system of the present invention can be applied. The multi-stage turbocharger system includes, for example, a series twin turbocharger system and a sequential twin turbocharger system.

It is a block diagram which shows the structure of the turbo supercharging system which is 1st Embodiment of this invention, and its cooling system. It is sectional drawing of the turbocharger which shows an example of a structure of the cooling channel | path provided in a turbine housing. It is sectional drawing of the turbocharger which shows another example of a structure of the cooling channel | path provided in a turbine housing. It is a block diagram which shows the structure of the turbocharging system which is 2nd Embodiment of this invention, and its cooling system. It is a block diagram which shows the structure of the turbocharging system which is 3rd Embodiment of this invention, and its cooling system. It is a block diagram which shows the structure of the turbocharging system which is 4th Embodiment of this invention, and its cooling system.

Explanation of symbols

10, 30, 40, 50 Turbocharger system 11 Low-pressure turbocharger 12 High-pressure turbocharger 11C, 12C Compressor 11T, 12T Turbine 13 Internal combustion engine 14 First exhaust passage 15 Second exhaust passage 16 Third exhaust Passage 17 Exhaust bypass passage 18 Exhaust switching valve 24, 27, 33 Cooling passage 25 Cooling passage valve 26 Exhaust throttle valve 28 Exhaust throttle valve bypass passage 29 Reverse support valve 31, 32 Exhaust catalyst 122, 123 Housing passage

Claims (8)

A first turbine driven by exhaust from an internal combustion engine;
A turbine housing that houses the first turbine;
An exhaust passage connected downstream of the first turbine;
A pressure loss generating element provided on the exhaust passage and generating a predetermined pressure loss;
A cooling passage that communicates the upstream side and the downstream side of the pressure loss generating element of the exhaust passage, and circulates the exhaust passage of the exhaust passage from the upstream side to the downstream side,
The cooling system for a turbocharger, wherein the cooling passage passes through the turbine housing, and the exhaust absorbs heat of the turbine housing.   2. The turbocharger cooling system according to claim 1, wherein a connection portion between the cooling passage and the exhaust passage on the downstream side of the pressure loss generating element is arranged on the upstream side of the exhaust catalyst.   The turbocharger comprising a plurality of turbine superchargers, wherein a second turbine is connected downstream of the first turbine, and the second turbine functions as the pressure loss generating element. The turbocharger cooling system according to any one of claims 1 and 2.   Used in a supercharging system comprising a plurality of turbine superchargers, a second turbine is connected downstream of the first turbine, the pressure loss generating element is provided downstream of the second turbine, and the cooling The turbocharger cooling system according to any one of claims 1 and 2, wherein a connection portion on the upstream side of the pressure loss generating element in the passage is disposed on the downstream side of the second turbine.   The turbocharger cooling system according to claim 4, wherein the pressure loss generating element is an exhaust throttle valve.   An exhaust throttle valve bypass passage communicating the upstream side and the downstream side of the exhaust throttle valve is provided, and only when the upstream pressure is higher than the downstream pressure in the exhaust throttle valve bypass passage The turbocharger cooling system according to claim 5, further comprising a reversely supported valve that opens.   5. The turbocharger according to claim 4, further comprising a plurality of exhaust catalysts connected in series to the exhaust passage, wherein the pressure loss generating element is an upstream side exhaust catalyst of the plurality of exhaust catalysts. Feeder cooling system. A cooling passage valve is provided in the cooling passage, and the cooling passage valve has a difference between an upstream pressure of the pressure loss generating element and a downstream pressure of the pressure loss generating element between an inlet and an outlet of the cooling passage. 2. The turbocharger cooling system according to claim 1, wherein the valve is opened when the pressure loss is greater than the pressure loss of the turbocharger.

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