JP5903264B2 - Multistage turbocharger - Google Patents

Description

  The present invention relates to a multistage supercharging device provided in an internal combustion engine and having a plurality of superchargers.

  As one of the supercharging devices for an internal combustion engine, a multistage supercharging device comprising a plurality of superchargers is known in order to enhance the supercharging effect. In this multi-stage turbocharger, for example, when the engine speed is small, the high-pressure stage supercharger with a small capacity is driven, and when the engine speed is large, the low-pressure stage supercharger with a large capacity is connected. It corresponds to a wide range of rotation by driving.

  FIG. 3 shows an example of a two-stage supercharging device composed of two superchargers. A two-stage supercharger 101 provided in the internal combustion engine 100 includes a low-pressure stage supercharger 103 and a high-pressure stage supercharger 104. The exhaust manifold 105 of the internal combustion engine main body 102 is connected to an exhaust side supercharging passage 107 communicating with an exhaust purification device (not shown), and a high pressure supercharger is disposed upstream of the exhaust side supercharging passage 107. 104 high-pressure turbine chamber 108 is connected. Further, the high pressure stage turbine chamber 108 is connected to the low pressure stage turbine chamber 110 of the low pressure stage supercharger 103 via the communication passage 109.

  As shown in FIG. 4, the first communication passage 109 connects the discharge port of the housing 111 having the high-pressure stage turbine chamber 108 on the inside and the introduction port of the housing 112 having the low-pressure stage turbine chamber 110 on the inside. Yes. In addition, an outlet side exhaust passage 113 communicating with the exhaust purification device is connected to an exhaust port of the housing 112 on the low pressure stage side. The exhaust discharged from the high-pressure stage housing 111 is supplied to the low-pressure stage housing 112 via the first communication passage 109. The exhaust discharged from the low-pressure stage side housing 112 is supplied to the outlet side exhaust passage 113.

  Further, as shown in FIG. 3, a bypass passage 114 that bypasses the high-pressure stage turbine chamber 108 branches from the upstream side of the high-pressure stage turbine chamber 108 in the exhaust side supercharging passage 107. A switching valve 115 is provided in the middle of the bypass passage 114. By opening and closing the valve 115, exhaust gas is supplied to the low-pressure turbine chamber 110 through the bypass passage 114, and a low-pressure from the high-pressure turbine chamber 108. The state to be supplied to the stage turbine chamber 110 is switched.

  Further, the exhaust purification device connected to the outlet side exhaust passage 113 includes an oxidation catalyst, a DPF that collects particulate matter (PM) in the exhaust, and the like. Recently, there is also an exhaust purification device equipped with a selective catalytic reduction (SCR) device that selectively purifies NOx (nitrogen oxides) in exhaust gas.

  As an example of this urea SCR device, there is one having a selective reduction catalyst in an exhaust passage and an addition valve for adding an aqueous urea solution to the exhaust passage. By this addition valve, the urea aqueous solution is added into the exhaust passage, whereby NOx in the exhaust is selectively reduced and removed on the catalyst.

  On the other hand, the two-stage supercharging device 101 has a problem that the temperature of the exhaust gas decreases as it moves through the route because the route of the exhaust side supercharging passage 107 becomes long. Therefore, as shown in FIG. 4, the exhaust temperature TL1 at the outlet of the low-pressure turbine chamber 110 is lower than the exhaust temperature TH at the outlet of the high-pressure turbine chamber 108. Further, since the exhaust discharged from the low-pressure turbine chamber 110 dissipates heat while passing through the outlet-side exhaust passage 113, the exhaust temperature TL2 at the outlet of the outlet-side exhaust passage 113 is the exhaust at the outlet of the low-pressure turbine chamber 110. It becomes lower than temperature TL1.

  If the temperature of the exhaust gas supplied to the exhaust gas purification device is lowered, there is a risk that the exhaust gas purification rate will be reduced. For example, the urea SCR device has high thermal responsiveness, and a decrease in exhaust temperature may cause a reduction reaction by ammonia not to be promoted, or cause a decrease in hydrolysis efficiency of an aqueous urea solution. Further, in the DPF, there is a possibility that the amount of PM deposition increases due to a temperature drop during catalyst regeneration, and the filter is likely to be clogged.

  In order to solve this problem, Patent Document 1 proposes an apparatus in which a small capacity catalyst is arranged between a high-pressure turbine chamber and a low-pressure turbine chamber. In this apparatus, the purification rate is improved by bringing the high-temperature exhaust gas discharged from the high-pressure turbine chamber into contact with the small-capacity catalyst.

JP 2010-121521 A

  However, the two-stage supercharging device 101 has a problem of increasing in size because a large number of pipes such as the communication passage 109 and the bypass passage 114 are provided, and there is a problem between the high-pressure turbine chamber 108 and the low-pressure turbine chamber 110. In the configuration in which the capacity catalyst is disposed, the mounting space for the multistage supercharging device is further expanded.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multi-stage supercharging device capable of increasing the exhaust purification rate while maintaining good mountability.

One aspect of the present invention is a multi-stage supercharging device for an internal combustion engine having a plurality of superchargers, wherein a high-pressure turbine chamber in which a turbine wheel of a high-pressure supercharger is accommodated and a turbine wheel of a low-pressure supercharger e Bei a communication passage that connects the low-pressure stage turbine chamber but housed, said low pressure turbine chamber, an outlet-side exhaust passage which connects the exhaust gas purifying device disposed downstream of the multistage supercharger the part of the communication passage and a portion of the outlet-side exhaust passage adjacent said communication passage and said outlet-side exhaust passage is provided in integral with the housing, and the communicating passage and the outlet-side exhaust passage The adjacent area is defined by a side wall portion of the housing, and the communication path has a shape that extends straight from the discharge port of the high pressure turbine chamber and then bends toward the low pressure turbine chamber side. Side wall portion of the housing Includes the bent portion is a portion bent to the low-pressure stage turbine chamber side among the communication path is to be located at a position facing the outlet of the high pressure turbine chamber.

  In one aspect of the present invention, the multi-stage supercharger has a configuration in which a communication passage to which high-temperature exhaust gas from the high-pressure stage turbine chamber is supplied and an outlet-side exhaust passage connected to the exhaust purification device are adjacent to each other. . For this reason, the thermal conductivity between the communication passage and the outlet side exhaust passage is enhanced, and the amount of heat transferred from the high temperature side exhaust gas in the communication passage to the low temperature side exhaust gas in the outlet side exhaust passage can be increased. it can. Therefore, it is possible to increase the temperature of the exhaust gas supplied to the exhaust gas purification device by effectively using the amount of heat of the exhaust gas flowing through the communication passage without providing a special device for improving the exhaust gas purification rate. For this reason, the purification efficiency of the exhaust emission control device can be increased while maintaining good mountability.

  In one aspect of the present invention, since the adjacent region of the communication passage and the outlet side exhaust passage is partitioned by the side wall portion of the housing, air having low thermal conductivity is interposed between the communication passage and the outlet side exhaust passage. do not do. For this reason, the amount of heat lost when heat is transferred from the communication passage to the outlet side exhaust passage can be reduced.

  In one aspect of the present invention, in the adjacent region where the communication passage and the outlet side exhaust passage are adjacent to each other, the flow of exhaust gas in the outlet side exhaust passage is opposite to the flow of exhaust gas in the communication passage. It is to become.

  In one aspect of the present invention, the multistage supercharging device has an arrangement in which the flow of the exhaust gas in the communication passage and the flow of the exhaust gas in the outlet side exhaust passage are reversed in the adjacent region. With such an arrangement, the communication path and the outlet-side exhaust path can be adjacent to each other while reducing the amount of change in the length of the path.

In one aspect of the present invention, the side wall portion of the housing constitutes a portion of the outlet side exhaust passage that is downstream of the discharge port of the low pressure turbine chamber.
In one aspect of the present invention, the communication passage is adjacent to the flow path downstream of the discharge port in the outlet side exhaust passage, so that heat is transferred to the exhaust gas immediately before being supplied to the exhaust purification device. be able to. For this reason, the loss amount after heat transfer can be reduced.
In one aspect of the present invention, the side wall portion of the housing constitutes a portion of the outlet side exhaust passage that is biased toward the exhaust purification device side with respect to the outlet of the low pressure turbine chamber.

One aspect of the present invention is that the outlet-side exhaust passage communicates with a urea selective reduction catalyst device.
In one of the aspects of the present invention, the outlet side exhaust passage communicates with the urea selective reduction catalyst device having high temperature responsiveness, so that the effect can be particularly exerted.

1 is a schematic view of an internal combustion engine of a first embodiment provided with a multistage supercharging device according to the present invention. Sectional drawing of the principal part of the exhaust system of the same multistage supercharging device. Schematic of the internal combustion engine provided with the conventional multistage supercharging device. Sectional drawing of the principal part of the exhaust system of the conventional multistage supercharging device.

Hereinafter, a first embodiment in which a multistage supercharging device of the present invention is embodied as a device mounted on a diesel engine will be described with reference to FIGS.
As shown in FIG. 1, the internal combustion engine 10 includes an intake passage 12 that supplies intake air taken in from the outside to the internal combustion engine body 11 and an exhaust passage 13 that discharges the exhaust sent from the internal combustion engine body 11 to the outside. I have. The internal combustion engine 10 also includes a two-stage supercharger 15 having a high-pressure stage supercharger 16 and a low-pressure stage supercharger 17.

  The high pressure supercharger 16 includes a high pressure turbine chamber 23 and a high pressure compressor chamber 24 in a housing 22. The high-pressure turbine chamber 23 accommodates a high-pressure turbine wheel 25 that rotates by supplying exhaust gas. The high-pressure compressor chamber 24 accommodates a high-pressure compressor wheel 26 that compresses intake air. These wheels 25 and 26 are connected to each other by a rotor shaft S1.

  The low pressure supercharger 17 has a larger volume than the high pressure supercharger 16. The low pressure stage supercharger 17 includes a low pressure stage turbine chamber 29 and a low pressure stage compressor chamber 30 in a housing 28. The low-pressure stage turbine chamber 29 accommodates a low-pressure stage turbine wheel 31 that rotates by exhaust. The low-pressure compressor chamber 30 accommodates a low-pressure compressor wheel 32 that compresses intake air. These wheels 31 and 32 are connected to each other by a rotor shaft S2.

  The two-stage supercharging device 15 includes an intake side supercharging passage 18 that constitutes a part of the intake passage 12. The intake side supercharging passage 18 is provided between an air cleaner 19 and an intercooler 20 provided in the middle of the intake passage 12.

  The intake side supercharging passage 18 includes an inlet side intake passage 33 provided between the air cleaner 19 and the low pressure compressor chamber 30. The intake-side supercharging passage 18 includes an intake-side communication passage 34 that connects the low-pressure compressor chamber 30 and the high-pressure compressor chamber 24. Further, the intake-side supercharging passage 18 includes an outlet-side intake passage 35 that connects the high-pressure compressor chamber 24 and the intercooler 20. An intake-side detour passage 36 is connected to the middle of the intake-side communication passage 34 and the outlet-side intake passage 35. An intake side switching valve 37 is provided in the middle of the intake side bypass passage 36, and the intake side bypass passage 36 is opened and closed by opening and closing the valve 37.

  The two-stage supercharging device 15 includes an exhaust side supercharging passage 21 that constitutes a part of the exhaust passage 13. The exhaust side supercharging passage 21 is provided between the exhaust manifold 51 and the exhaust purification device 55 of the internal combustion engine body 11.

  The exhaust side supercharging passage 21 includes an inlet side exhaust passage 38 provided between the exhaust manifold 51 and the high pressure turbine chamber 23. The exhaust-side supercharging passage 21 includes an exhaust-side communication passage 40 that allows the high-pressure turbine chamber 23 and the low-pressure turbine chamber 29 to communicate with each other. Further, the exhaust-side supercharging passage 21 includes an outlet-side exhaust passage 41 that allows the low-pressure stage turbine chamber 29 and the exhaust purification device 55 to communicate with each other.

  An exhaust side bypass passage 42 is connected between the middle of the inlet side exhaust passage 38 and the exhaust side communication passage 40. In the middle of the exhaust side bypass passage 42, an exhaust side switching valve 43 is provided. By opening and closing the valve 43, the exhaust side bypass passage 42 is opened and closed.

Further, an oxidation catalyst 56, a DPF 57, and a urea SCR device 58 are connected to the outlet side exhaust passage 41 in order from the upstream side of the exhaust passage 13.
In the low engine speed range where the engine speed is low, the intake side switching valve 37 and the exhaust side switching valve 43 are closed. As a result, the exhaust delivered from the exhaust manifold 51 is supplied to the high-pressure turbine chamber 23 via the inlet-side exhaust passage 38. Exhaust gas sent out from the high-pressure stage turbine chamber 23 is supplied to the low-pressure stage turbine chamber 29 via the exhaust-side communication passage 40 and sent out from the low-pressure stage turbine chamber 29 to the exhaust purification device 55 side.

  Since the amount of exhaust is small in the low rotation range, the exhaust is arranged on the upstream side and rotates only the high-pressure stage turbine wheel 25 smaller than the low-pressure stage turbine wheel 31. For this reason, the low-pressure stage turbine wheel 31 is almost stopped.

  Further, the intake air taken from the air cleaner 19 through the inlet side intake passage 33 is supplied to the low-pressure stage compressor chamber 30. The intake air sent out from the low-pressure stage compressor chamber 30 is supplied to the high-pressure stage compressor chamber 24 via the intake side communication passage 34. As described above, since only the high-pressure turbine wheel 25 rotates in the low rotation region, the high-pressure compressor wheel 26 connected to the wheel 25 rotates, and the intake air supplied to the high-pressure compressor chamber 24 is compressed. Then, it is pumped to the intercooler 20 side that is the downstream side. The intake air cooled by the intercooler 20 is supplied to the intake manifold 50 of the internal combustion engine body 11.

  In the high rotation range of the internal combustion engine body 11, the intake side switching valve 37 and the exhaust side switching valve 43 are opened. As a result, the exhaust gas sent out from the exhaust manifold 51 is supplied to the low-pressure turbine chamber 29 via the inlet-side exhaust passage 38 and the exhaust-side bypass passage 42. As a result, the low-pressure stage turbine wheel 31 rotates and is driven by the wheel 31 to rotate the low-pressure stage compressor wheel 32.

  The intake air taken from the air cleaner 19 via the inlet side intake passage 33 is supplied to the low pressure compressor chamber 30 and compressed by the rotating low pressure compressor wheel 32. The compressed intake air is sent to the intercooler 20 side through the intake side communication passage 34 and the intake side bypass passage 36.

  Next, the configuration of the exhaust side supercharging passage 21 of the two-stage supercharging device 15 will be described. As shown in FIG. 2, the exhaust-side communication passage 40 that connects the high-pressure stage turbine chamber 23 and the low-pressure stage turbine chamber 29, and the outlet-side exhaust that supplies the exhaust sent from the low-pressure stage turbine chamber 29 to the exhaust purification device 55. The passage 41 is formed integrally with an exhaust system housing 47 formed by casting or the like.

  The exhaust-side communication path 40 connects the discharge port of the high-pressure stage turbine housing 45 having the high-pressure stage turbine chamber 23 inside and the introduction port of the low-pressure stage turbine housing 46 having the low-pressure stage turbine chamber 29 inside. The exhaust side communication passage 40 extends linearly from the high pressure turbine housing 45 and then bends toward the low pressure turbine housing 46 side. Further, the exhaust side communication passage 40 includes an extending portion 40 b extending from the bent portion 40 a toward the introduction port of the low-pressure stage turbine housing 46. The bent portion 40 a and a part of the extended portion 40 b are adjacent to the outlet side exhaust passage 41 via the side wall portion 48 of the exhaust system housing 47.

  Further, the outlet side exhaust passage 41 connects the discharge port of the low-pressure turbine housing 46 and the inlet (not shown) of the exhaust purification device 55. The outlet side exhaust passage 41 is bent so as to be biased toward the exhaust side communication passage 40 toward the exhaust purification device 55 from the low pressure stage turbine housing 46, and the bent side 40 a and the extension portion 40 b of the exhaust side communication passage 40 are , They are in contact with each other through the side wall 48. Further, in the outlet side exhaust passage 41, the adjacent region 49 in contact with the exhaust side communication passage 40 is biased to the downstream side of the outlet side exhaust passage 41, that is, the exhaust purification device 55 side.

  In this way, the exhaust side communication passage 40 and the outlet side exhaust passage 41 that flow in different directions communicate with each other. Therefore, in the adjacent region 49, the exhaust gas flow in the exhaust side communication passage 40 is in the outlet side exhaust passage 41. The flow of exhaust gas is almost in the opposite direction. With this layout, for example, in order to make the exhaust side communication path 40 and the outlet side exhaust path 41 adjacent to each other, the upstream side exhaust side communication path 40 is extended to a position adjacent to the downstream side outlet side exhaust path 41. There is no.

  On the other hand, the exhaust temperature TH in the vicinity of the discharge port of the high-pressure stage turbine chamber 23 is higher than the exhaust temperature TL1 in the vicinity of the discharge port of the low-pressure stage turbine chamber 29, but as described above, the exhaust side communication passage 40 and the outlet side exhaust passage 41. , The heat is easily transferred from the exhaust side communication passage 40 to the outlet side exhaust passage 41 via the side wall 48. As a result, the amount of heat transferred from the high temperature side exhaust side communication passage 40 to the low temperature side outlet side exhaust passage 41 increases, and the exhaust gas temperature in the outlet side exhaust passage 41 rises.

  As a result, in the outlet side exhaust passage 41, the exhaust temperature TL2 downstream of the region 49 adjacent to the exhaust side communication passage 40 and in the vicinity of the inlet of the exhaust purification device 55 is in the vicinity of the outlet of the low pressure turbine chamber 29. It becomes higher than the exhaust temperature TL1 (TL1 <TL2 <TH). For this reason, the temperature of the exhaust gas supplied to the exhaust gas purification device 55 rises, and the purification efficiency of the DPF 57 and the urea SCR device 58 can be increased. Further, since the adjacent region 49 between the outlet side exhaust passage 41 and the exhaust side communication passage 40 is biased to the exhaust purification device 55 side with respect to the outlet of the outlet side exhaust passage 41, immediately before flowing into the exhaust purification device 55. Heat is transferred to the exhaust gas.

At this time, since air (outside air) having a temperature lower than that of the exhaust gas does not intervene between the exhaust side communication passage 40 and the outlet side exhaust passage 41, the amount of loss in heat transfer is reduced.
As described above, according to the embodiment, the effects listed below can be obtained.

  (1) According to the above embodiment, the two-stage supercharging device 15 includes the exhaust-side communication passage 40 to which high-temperature exhaust gas from the high-pressure turbine chamber 23 is supplied, and the outlet-side exhaust passage connected to the exhaust purification device 55. 41 is adjacent. For this reason, the amount of heat transferred from the high-temperature exhaust gas flowing through the exhaust-side communication passage 40 to the low-temperature exhaust gas flowing through the outlet-side exhaust passage 41 can be increased. Therefore, it is possible to increase the temperature of the exhaust gas supplied to the exhaust gas purification device 55 by effectively using the amount of heat of the exhaust gas flowing through the exhaust side communication passage 40 without separately providing a special device for improving the exhaust gas purification rate. Therefore, the purification efficiency of the exhaust emission control device 55 can be increased while maintaining good mountability.

  (2) According to the above embodiment, the exhaust side communication passage 40 and the outlet side exhaust passage 41 are formed integrally with the exhaust system housing 47. That is, since the adjacent region 49 of the exhaust side communication passage 40 and the outlet side exhaust passage 41 is partitioned by the side wall portion 48 of the exhaust system housing 47, the exhaust gas is disposed between the exhaust side communication passage 40 and the outlet side exhaust passage 41. Air (outside air) having a lower temperature is not present. For this reason, it is possible to reduce a loss amount when heat is transmitted from the exhaust side communication passage 40 to the outlet side exhaust passage 41.

  (3) According to the above embodiment, the two-stage supercharging device 15 is disposed in the adjacent region 49 of the exhaust side communication passage 40 and the outlet side exhaust passage 41 so that the flow of exhaust gas in those flow paths is reversed. Have. For this reason, the exhaust side communication passage 40 and the outlet side exhaust passage 41 are easily arranged adjacent to each other. With such an arrangement, the exhaust side communication passage 40 and the outlet side exhaust passage 41 can be adjacent to each other without substantially changing the length of the path.

  (4) In the above embodiment, the exhaust side communication passage 40 is adjacent to the flow path on the downstream side of the discharge port in the outlet side exhaust passage 41, so that the exhaust gas immediately before being supplied to the exhaust purification device 55 is removed. The temperature can be raised. For this reason, the amount of heat lost after heat is transmitted to the outlet side exhaust passage 41 can be reduced.

  (5) In the above embodiment, since the outlet side exhaust passage 41 communicates with the urea SCR device 58 having high temperature responsiveness, the purification efficiency can be drastically improved only by raising the exhaust temperature of the outlet side exhaust passage 41 several times. Can be particularly effective.

In addition, the said embodiment can also be suitably changed and implemented as follows.
In the above embodiment, the exhaust side communication passage 40 and the outlet side exhaust passage 41 are formed integrally with the exhaust system housing 47, but the exhaust side communication passage 40 and the outlet side exhaust respectively formed in separate housings. You may make it arrange | position in the state which contact | connected the channel | path 41. FIG. At this time, the adjacent region may be thinned.

In the above embodiment, the exhaust flow in the exhaust side communication passage 40 and the exhaust flow in the outlet side exhaust passage 41 are arranged in opposite directions, but other arrangements may be used.
In the above embodiment, the exhaust side communication passage 40 is adjacent to the downstream side position of the outlet side exhaust passage 41, but may be adjacent to the outlet of the outlet side exhaust passage 41.

  In the above embodiment, the high pressure stage supercharger 16 is driven at the time of low speed rotation, and the low pressure stage supercharger 17 is driven at the time of high speed rotation, but the drive system may be other than this. For example, the high-pressure supercharger 16 and the low-pressure supercharger 17 may be driven during high-speed rotation by causing the intake-side switching valve 37 and the exhaust-side switching valve 43 to function as flow rate adjustment valves.

  In the above embodiment, the multi-stage supercharger is embodied as the two-stage supercharger 15 including the high-pressure stage supercharger 16 and the low-pressure stage supercharger 17, but it may be provided with a plurality of superchargers. That's fine.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 15 ... Two-stage supercharger, 16 ... High pressure stage supercharger, 17 ... Low pressure stage supercharger, 22, 28 ... Housing, 23 ... High pressure stage turbine chamber, 25, 31 ... Turbine wheel, 29 DESCRIPTION OF SYMBOLS ... Low pressure turbine chamber, 40 ... Exhaust side communication passage, 41 ... Outlet side exhaust passage, 47 ... Exhaust system housing, 48 ... Side wall portion, 49 ... Adjacent region, 55 ... Exhaust gas purification device, 58 ... Urea selective reduction catalyst device .

Claims (5)

In a multistage supercharging device for an internal combustion engine comprising a plurality of superchargers,
A communication path connecting a high-pressure stage turbine chamber in which the turbine wheel of the high-pressure stage turbocharger is accommodated and a low-pressure stage turbine chamber in which the turbine wheel of the low-pressure stage supercharger is accommodated;
E Bei said low pressure turbine chamber, an outlet-side exhaust passage which connects the exhaust gas purifying device disposed downstream of the multistage supercharging device,
A part of the communication passage and a part of the outlet side exhaust passage are adjacent ,
The communication passage and the outlet side exhaust passage are integrally provided in a housing,
An adjacent region where the communication passage and the outlet side exhaust passage are adjacent is partitioned by a side wall portion of the housing,
The communication path has a shape that bends toward the low-pressure stage turbine chamber side after linearly extending from the discharge port of the high-pressure stage turbine chamber,
The side wall portion of the housing includes a bent portion that is a portion bent to the low-pressure stage turbine chamber side in the communication path, and is positioned at a position facing the discharge port of the high-pressure turbine chamber. Multistage supercharger. 2. The multistage according to claim 1, wherein in the adjacent region where the communication passage and the outlet side exhaust passage are adjacent to each other, the flow of the exhaust gas in the outlet side exhaust passage is opposite to the flow of the exhaust gas in the communication passage. Supercharger. The multistage supercharging device according to claim 1 or 2 , wherein the side wall portion of the housing constitutes a portion of the outlet side exhaust passage that is downstream of the discharge port of the low pressure turbine chamber.   4. The multistage turbocharging device according to claim 3, wherein the side wall portion of the housing constitutes a portion of the outlet side exhaust passage that is biased toward the exhaust purification device with respect to the discharge port of the low pressure turbine chamber.   The multistage supercharging device according to any one of claims 1 to 4, wherein the outlet side exhaust passage communicates with a urea selective reduction catalyst device.

Images