JP6399042B2 - Turbocharged engine - Google Patents

Description

  The present invention relates to a turbocharged engine in which a turbocharger having two independent turbo parts is attached to an engine body.

  In an engine with a turbocharger, a turbocharger that supercharges intake air using the exhaust energy of the engine is attached adjacent to one side wall of the engine body. An exhaust passage and an intake passage are provided in a housing of the turbocharger, and a turbine chamber for accommodating a turbine is communicated with the exhaust passage, and a compressor chamber for accommodating a compressor fan is communicated with the intake passage. . Exhaust gas is supplied from the engine body to the exhaust passage, and intake air supplied to the engine body flows through the intake passage. The exhaust rotates the turbine around the turbine shaft, rotates the compressor fan in the compressor chamber connected to the turbine shaft, and supercharges the intake air.

  Conventionally, a turbocharger in which two independent turbo units are arranged in series in the exhaust path is known. For example, Patent Document 1 discloses a two-stage turbocharger that includes a large turbo unit that mainly operates in a medium to high speed rotation region of an engine and a small turbo unit that mainly operates in a low speed rotation region. Yes. Each of these large and small turbo units includes a turbine chamber and a compressor chamber, and a turbine shaft extending between the two chambers.

Japanese Patent No. 5499953

  In the turbocharger, in order to improve the supercharging efficiency, it is required to supply intake air to the compressor chamber without generating resistance (intake resistance) as much as possible in the flow of intake air. However, in the case of an engine equipped with a two-stage turbocharger, it is difficult to reduce the intake resistance because the route of the intake passage is complicated and the compactness of the apparatus is also required. In particular, in the intake passage, the inter-compressor passage between the compressor chamber arranged on the upstream side and the compressor chamber arranged on the downstream side must be greatly curved due to layout restrictions and the intake resistance increases. Tend.

  An object of the present invention is to reduce intake resistance and improve supercharging efficiency in an engine equipped with a turbocharger in which two independent turbo units are arranged in series in an exhaust and intake passage. Is to provide a turbocharged engine.

An engine with a turbocharger according to one aspect of the present invention includes an engine body including a cylinder and an engine output shaft, an exhaust passage that is disposed adjacent to the engine body, and is supplied with exhaust from the engine body, and the engine A turbocharger that supercharges the intake air, the turbocharger including a first turbine chamber with a built-in first turbine that communicates with the exhaust passage; A first turbo section including a first compressor chamber having a built-in first compressor communicating with an intake passage, and a first turbine shaft extending between the two chambers and connecting the first turbine and the first compressor; A second turbine chamber with a built-in second turbine that communicates with the exhaust passage, a second compressor chamber with a built-in second compressor that communicates with the intake passage, and the second turbine chamber that extends between these two chambers. And a second turbo unit and a second turbine shaft for connecting the second compressor and turbine, the inlet of the first compressor chamber is arranged on the axis of said first turbine shaft, the first The two compressor chambers are disposed upstream of the first compressor chamber in the intake passage, and have a scroll portion that forms a spiral intake passage around the second compressor, and the first turbine shaft and the The second turbine shaft is disposed so as to extend substantially in the same direction as the engine output shaft, and in plan view in the axial direction of the cylinder, the second turbine shaft is the first turbine shaft relative to the engine output shaft. in turbocharged engine located on the side farther from the first turbine shaft, said first, said second turbine shaft first, you the side view seen from the second compressor chamber side Te, upstream of the scroll portion is accessible from the side farther from the second turbine shaft with respect to the engine body in the lateral direction, the first gradually the engine body in a direction of separating from the compressor chamber The first turbine shaft disposed on the side closer to the engine main body in the left-right direction is closer to the engine main body while moving closer to the engine main body. The scroll portion is scrolled in the downstream direction, and the downstream end portion of the scroll portion is an outlet of the second compressor chamber, and the outlet is in a direction perpendicular to the second turbine shaft and faces the first turbine shaft. An inter-compressor passage that opens in the direction from the outlet of the second compressor chamber to the inlet of the first compressor chamber is connected to the second turbine shaft. It is arranged on the engine body side, extends from the outlet of the second compressor chamber in the tangential direction of the downstream end of the scroll portion, and extends in the direction toward the first turbine shaft. Features.

  According to this turbocharged engine, the second compressor chamber is disposed upstream of the first compressor chamber in the intake passage. For this reason, the passage between the compressors is provided at the outlet of the second compressor chamber that will be present around the second turbine shaft (scroll outlet), and at the first compressor chamber that opens in the axial direction of the first turbine shaft. Connect the entrance. In addition, since the second turbine shaft is disposed farther than the first turbine shaft with respect to the engine output shaft, according to the side view, the first turbine shaft is shifted to the left side of the second turbine shaft. Exists. And since the said 2nd turbine shaft rotates counterclockwise, it becomes easy to make the position of the exit of a 2nd compressor chamber correspond with the position of the entrance of a 1st compressor chamber in the left-right direction. In addition, since the inter-compressor passage is disposed closer to the engine body than the second turbine shaft, the inter-compressor passage can be a passage that hardly needs to be naturally curved in the side view. Therefore, the intake resistance of the intake air flowing through the compressor passage can be suppressed to a low level.

In the above turbocharged engine, in the side view, the distance A between the center of the first turbine shaft and the second turbine shaft in the left-right direction is when the outer diameter of the second compressor is B. ,
B / 2 ≦ A ≦ B
It is desirable to be set within the range.

  According to this turbocharged engine, since the center-to-axis distance A in the left-right direction of the first and second turbine shafts is set in the above range, the inlet of the first compressor chamber is connected to the second turbine shaft. It is not too far apart in the left-right direction. Therefore, the passage between the compressors can be a passage with less curvature in the side view.

  In the above turbocharged engine, in the side view, the inter-compressor passage includes a straight portion extending linearly from a downstream end of the scroll portion of the second compressor chamber, a downstream end of the straight portion, And a bending portion that connects the inlet portion of the first compressor chamber along the first turbine axis.

  According to the turbocharged engine, since the intercompressor passage can be formed by the straight portion except for the bent portion near the inlet portion of the first compressor chamber, the intake resistance in the intercompressor passage is reduced. Can be suppressed.

  Alternatively, in the side view, the passage between the compressors is an arcuate curved passage that connects a downstream end of the scroll portion of the second compressor chamber and an inlet portion along the first turbine axis of the first compressor chamber. It can be set as the structure which is.

  According to this turbocharged engine, since the intercompressor passage can be an arcuate curved passage, that is, a generally gently curved passage, the intake resistance in the intercompressor passage can be kept low. .

  In the engine with a turbocharger, a blow-by recirculation path that joins blow-by gas to the intake passage may be connected upstream of the second compressor chamber in the intake passage.

  When the blow-by return path is connected to the upstream side of the second compressor chamber, if there is a portion where the flow of intake air is disturbed (intake resistance is high) in the intake passage downstream of the blow-by return path, Oil may accumulate. According to the above turbocharged engine, the flow of intake air in the intercompressor passage disposed downstream of the blow-by recirculation passage is not disturbed, so that the accumulation of oil can be prevented in advance.

  According to the present invention, in an engine equipped with a turbocharger in which two independent turbo units are arranged in series in the exhaust and intake paths, it is possible to reduce intake resistance and improve supercharging efficiency. A turbocharged engine can be provided.

FIG. 1 is a perspective view of a turbocharged engine according to an embodiment of the present invention. FIG. 2 is a perspective view of the turbocharger portion of the engine, partly broken away. FIG. 3 is a perspective view of the turbocharger. FIG. 4 is a side view of the turbocharger. FIG. 5 is a diagram schematically showing the configuration of the turbocharged engine and its peripheral components, and the flow of intake and exhaust. FIG. 6 is a side view of the turbocharger showing the intake flow in the turbocharger in the low-speed rotation region of the engine body. FIG. 7 is a side view of the turbocharger showing the intake flow in the turbocharger in the medium speed and high speed rotation regions of the engine body. FIG. 8 is a side view of the turbocharger according to the embodiment as seen from the compressor chamber side. FIG. 9 is a top view of the engine (a plan view in the axial direction of the cylinder). FIG. 10 is a schematic diagram showing the arrangement relationship between the large and small turbo shafts. FIG. 11 is a schematic diagram showing the arrangement relationship between the large and small turbo shafts. FIG. 12 is a side view of a turbocharger according to a modified embodiment as viewed from the compressor chamber side.

[Schematic configuration of the engine]
Hereinafter, an engine with a turbocharger according to an embodiment of the present invention will be described in detail based on the drawings. First, a schematic configuration of the engine will be described. FIG. 1 is a perspective view of a turbocharger-equipped engine 1 according to an embodiment of the present invention, and FIG. 2 is a perspective view showing a part of the turbocharger 3 of the engine 1 with a part broken away. In FIG. 1, FIG. 2 and other drawings, front / rear, left / right and up / down direction indications are attached. This is for convenience of explanation and does not necessarily indicate the actual direction.

  The turbocharged engine 1 includes a multi-cylinder engine main body 10, an exhaust manifold 14 connected to the left side surface of the engine main body 10, an unillustrated intake manifold, and a left side of the engine main body 10. And a turbocharger 3 arranged. 1, the exhaust manifold 14 is surrounded by a manifold insulator 15, the left side surface of the engine body 10 is covered by an engine body insulator 16, and the turbocharger 3 is surrounded by a turbo insulator. 17 is covered.

  The engine body 10 is an in-line four-cylinder diesel engine, and includes a cylinder block 11, a cylinder head 12 attached to the upper surface of the cylinder block 11, and a cylinder head cover 13 disposed above the cylinder head 12. . The cylinder block 11 includes four cylinders 2 (see FIG. 9) that form fuel combustion chambers.

  The exhaust manifold 14 includes therein a manifold passage that collects exhaust gas discharged from the exhaust port 25 (FIG. 5) of each cylinder 2 into one flow path. The inlet side of the exhaust manifold 14 is connected to the cylinder head 12, and the outlet side is connected to the turbocharger 3. The intake manifold includes a manifold passage for supplying intake air from one intake passage to the intake port 24 of each cylinder 2.

  The turbocharger 3 is disposed adjacent to the left rear side of the engine body 10 and supercharges intake air introduced into the engine body 10 using exhaust energy discharged from the engine body 10. It is. The turbocharger 3 is a large turbo unit 3A (second turbo unit) that operates in the entire rotation region of the engine body 10 and supercharges intake air, and a small size that operates mainly in the low speed rotation region and supercharges intake air. A turbo unit 3B (first turbo unit).

  In the present embodiment, a small turbo unit 3B is continuously provided below the large turbo unit 3A. Each of the large turbo unit 3A and the small turbo unit 3B includes a turbine chamber disposed on the front side and a compressor chamber disposed on the rear side. In the turbocharger 3, an intake passage through which the exhaust gas is supplied from the engine main body 10 through the turbine chambers, and an intake air through which the intake air supplied to the engine main body 10 through the compressor chambers circulates. And a passage. That is, the turbine chambers are incorporated in the exhaust passage of the engine body 10, and the compressor chambers are incorporated in the intake passage of the engine body 10.

  The manifold insulator 15 is an insulator that shields peripheral components from being damaged by heat generated by the exhaust manifold 14 through which high-temperature exhaust flows. The engine body insulator 16 protects the cylinder head cover 13, the harness, and the sensors from the heat generated from the exhaust manifold 14 and the turbocharger 3. The turbo insulator 17 is an insulator that covers the periphery of the turbine chamber of the turbocharger 3 through which high-temperature exhaust gas circulates and suppresses thermal damage to peripheral components.

[External structure of turbocharger]
FIG. 3 is a perspective view of the turbocharger 3, and FIG. 4 is a side view of the turbocharger 3. The large turbo unit 3A includes a large turbine case 31T disposed on the front side and a large compressor case 31C disposed on the rear side. Similarly, the small turbo unit 3B includes a small turbine case 32T disposed on the front side and a small compressor case 32C disposed on the rear side. A small turbine case 32T is disposed below the large turbine case 31T, and a small compressor case 32C is disposed below the large compressor case 31C.

  The large turbine case 31T defines a large turbine chamber 33 (FIG. 5) communicating with the exhaust passage. The large turbine case 31T includes a sheet metal housing 311 made of a sheet metal case, an upper flange portion 312 that supports the lower end of the sheet metal housing 311, and an exhaust side having an exhaust port that serves as an outlet for exhaust from the turbocharger 3. A flange portion 313. A downstream pipe of the exhaust passage is connected to the exhaust side flange portion 313.

  The small turbine case 32T defines a small turbine chamber 35 (FIG. 5) communicating with the exhaust passage. The small turbine case 32T is a housing made of a cast iron case, and is integrally provided with an exhaust introduction flange portion 321 on the upstream side of the exhaust passage and a lower flange portion 322 on the downstream side. The exhaust introduction flange portion 321 is a flange portion for connecting to the exhaust manifold 14, and an exhaust introduction port 51 </ b> A that serves as an inlet for exhaust gas to the turbocharger 3 is formed. The lower flange portion 322 is a flange portion for connecting to the large turbine case 31T.

  A flange stud 312A protrudes downward from the lower surface of the upper flange portion 312 of the large turbine case 31T. On the other hand, the lower flange portion 322 of the small turbine case 32T is provided with a through hole that receives the flange stud 312A. The upper flange portion 312 is placed on the lower flange portion 322, and both are bolted using the flange stud 312A, whereby the large turbine case 31T and the small turbine case 32T (the large turbo portion 3A and the small turbo portion). 3B) are integrated.

  The large compressor case 31C defines a large compressor chamber 34 (FIG. 5) communicating with the intake passage. The large compressor case 31C is made of, for example, an aluminum case, and includes an intake air introducing flange portion 314, a large scroll portion 315, and a first coupling portion 316. The intake air introduction flange portion 314 is a flange portion in which an intake air introduction port 45 </ b> A serving as an intake air inlet to the turbocharger 3 is formed. The large scroll portion 315 forms a part of the large compressor chamber 34, and forms a spiral intake passage around the large compressor 34B (FIG. 5). The first coupling part 316 is a cylindrical part located at the downstream end of the large scroll part 315 and having an inner diameter larger than that of the upstream part of the large scroll part 315. The first coupling portion 316 is open downward and serves as an outlet for intake air from the large compressor case 31C.

  The small compressor case 32C defines a small compressor chamber 36 (FIG. 5) communicating with the intake passage. The large compressor chamber 34 is disposed upstream of the small compressor chamber 36 in the intake passage. The small compressor case 32C is made of, for example, an aluminum case, and includes a second coupling portion 323, a small scroll portion 324, a downstream housing 325, and an intake discharge flange portion 326.

  The second coupling portion 323 is a cylindrical portion that serves as an inlet for intake air into the small compressor case 32C, and is open upward. The second coupling part 323 is a cylindrical body having the same inner diameter as that of the first coupling part 316, and both the coupling parts 316 and 323 are arranged so that the openings of the both faces in the vertical direction. The downstream side of the second coupling portion 323 communicates with the inlet of the small compressor chamber 36.

  A cold decoupler 317 made of a cylindrical tube is interposed between the coupling portions 316 and 323. The cold decoupler 317 is a coupling pipe having a sealing layer made of fluorine rubber or the like on the outer peripheral surface of a flexible cylindrical tube. An upper end portion of the cold decoupler 317 is inserted into the first coupling portion 316 in an airtight manner, a lower end portion is inserted into the second coupling portion 323 in an airtight manner, and an intermediate portion is exposed to the outside.

  The small scroll portion 324 forms a part of the small compressor chamber 36, and forms a spiral intake passage around the small compressor 36B (FIG. 5). The downstream housing 325 forms an intake passage (intake bypass passage 49) that bypasses the intake passage on the downstream side of the small scroll portion 324 and the small compressor chamber 36. The intake / discharge flange portion 326 is a flange portion in which an intake / discharge port 48 </ b> A serving as an outlet for intake air to the turbocharger 3 is formed.

[Internal structure of engine]
FIG. 5 is a diagram schematically showing the configuration of the turbocharged engine 1 and its peripheral components, and the flow of intake and exhaust. The engine 1 includes an engine body 10, an intake passage P1 for introducing combustion air into the engine body 10, an exhaust passage P2 for discharging combustion gas (exhaust gas) generated in the engine body 10, and the like. A turbocharger 3 having passages that respectively constitute part of the intake passage P1 and the exhaust passage P2, an exhaust purification device 70 disposed near the downstream end of the exhaust passage P2, an intake passage P1 and an exhaust passage P2. EGR (Exhaust Gas Recirculation) device 80 disposed between the two.

  Each cylinder 2 of the engine body 10 is provided with a piston 21, a combustion chamber 22, a crankshaft 23, an intake port 24, an exhaust port 25, an intake valve 26 and an exhaust valve 27. In FIG. 5, one cylinder 2 is shown. The piston 21 is accommodated in the cylinder 2 so as to be able to reciprocate. The combustion chamber 22 is formed above the piston 21 in the cylinder 2. Diesel fuel is injected into the combustion chamber 22 from an unillustrated injector. The fuel injected from the injector is mixed with the air supplied from the intake passage P <b> 1 and self-ignited in the combustion chamber 22. The piston 21 is pushed down by the expansion force due to the combustion and reciprocates in the vertical direction.

  The crankshaft 23 is an output shaft of the engine body 10 and is disposed below the piston 21. The piston 21 and the crankshaft 23 are connected to each other via a connecting rod. The crankshaft 23 rotates around its central axis according to the reciprocating motion of the piston 21. The intake port 24 is an opening through which air (intake air) supplied from the intake passage P <b> 1 is introduced into the cylinder 2. The exhaust port 25 is an opening for leading exhaust generated by the combustion of fuel in the cylinder 2 to the exhaust passage P2. The intake valve 26 is a valve that opens and closes the intake port 24, and the exhaust valve 27 is a valve that opens and closes the exhaust port 25.

  In the intake passage P1, an air cleaner 41, a compressor section (a large compressor chamber 34 and a small compressor chamber 36) of the turbocharger 3, an intercooler 42, and a throttle valve 43 are provided in this order from the upstream side of the intake flow. . The downstream end of the intake passage P1 is connected to the intake port 24 via the intake manifold 18 (FIG. 8). The air cleaner 41 purifies the air taken into the intake passage P1. The intercooler 42 cools the intake air sent to the combustion chamber 22 through the intake port 24. The throttle valve 43 is a valve that adjusts the amount of intake air sent to the combustion chamber 22. A blow-by recirculation passage 411 for sending blow-by gas to the combustion chamber 22 is connected to the upstream side of the turbocharger 3 in the intake passage P1. The intake air is supercharged when passing through the compressor section of the turbocharger 3 described in detail later.

  The upstream end of the exhaust passage P <b> 2 is connected to the exhaust port 25 via the exhaust manifold 14. The exhaust passage P2 is provided with the turbine section (the small turbine chamber 35 and the large turbine chamber 33) of the turbocharger 3 and the exhaust purification device 70 in order from the upstream side of the exhaust flow. The exhaust purification device 70 includes a catalyst device 71 including a NOx storage reduction catalyst that temporarily stores NOx in the exhaust and then reduces the NOx, and a DPF (Diesel Particulate Filter) 72 that collects particulate matter in the exhaust. . The kinetic energy of the exhaust gas is recovered when the exhaust gas passes through the turbine section of the turbocharger 3.

  The EGR device 80 is a device for recirculating a part of exhaust gas (EGR gas) discharged from the engine body 10 to intake air. The EGR device 80 includes a first EGR passage 81 and a second EGR passage 84 that allow the exhaust passage P2 and the intake passage P1 to communicate with each other, and a first EGR valve 82 and a second EGR valve 85 that open and close the passages 81 and 84, respectively. An EGR cooler 83 is provided in the first EGR passage 81. The EGR gas is cooled by the EGR cooler 83 while passing through the first EGR passage 81 and then flows into the intake passage P1. On the other hand, the EGR cooler is not provided in the second EGR passage 84, and the EGR gas can flow into the intake passage P1 at a high temperature. The first and second EGR passages 81 and 84 communicate a portion of the exhaust passage P2 upstream of the turbocharger 3 and a portion of the intake passage P1 downstream of the throttle valve 43. Therefore, the exhaust before being introduced into the turbine part of the turbocharger 3 is supplied to the intake port 24 together with the intake air.

[Details of turbocharger]
Next, the detailed structure of the turbocharger 3 according to the present embodiment will be described with reference to FIGS. As described above, the turbocharger 3 includes the large turbo unit 3A for medium speed to high speed rotation region operation and the small turbo unit 3B for low speed rotation region operation. The large turbo unit 3A includes a large turbine chamber 33 (second turbine chamber) and a large compressor chamber 34 (second compressor chamber). Similarly, the small turbo unit 3B includes a small turbine chamber 35 (first turbine chamber) and a small compressor chamber 36 (first compressor chamber). The large turbine chamber 33 and the small turbine chamber 35 communicate with the exhaust passage P2, and the large compressor chamber 34 and the small compressor chamber 36 communicate with the intake passage P1.

  The large turbine chamber 33 includes a large turbine 33T (second turbine), and the large compressor chamber 34 includes a large compressor 34B (second compressor). The large turbine 33T and the large compressor 34B are connected by a large turbine shaft 37 (second turbine shaft). The large turbine shaft 37 extends between the large turbine chamber 33 and the large compressor chamber 34, the large turbine 33T is attached to one end of the large turbine shaft 37, and the large compressor 34B is attached to the other end. The large turbine 33 </ b> T receives the exhaust flow (kinetic energy) and rotates around the large turbine shaft 37. The large compressor 34B also rotates around the axis of the large turbine shaft 37 to compress (supercharge) the intake air. When the large turbine 33T rotates upon receiving the kinetic energy of the exhaust, the large compressor 34B also rotates integrally around the axis of the large turbine shaft 37.

  As the large turbine 33T, an impeller that has a plurality of blades and rotates around the large turbine shaft 37 when exhaust collides with the blades can be used. The large turbine 33T has a VGT (Variable Geometry Turbocharger) specification to which a variable vane mechanism 39 for changing the exhaust flow velocity (turbine capacity) is attached. The variable vane mechanism 39 includes a plurality of nozzle vanes that are disposed on the outer peripheral portion of the large turbine 33T and capable of changing the angle. By adjusting the angle of the nozzle vanes, the flow area of the exhaust gas flowing into the large turbine 33T is changed, thereby adjusting the flow velocity of the exhaust gas. The nozzle vane angle is adjusted by the VGT actuator 39A. Since the variable vane mechanism 39 is mounted, the large turbine chamber 33 (large turbine case 31T) needs to be enlarged.

  The small turbine chamber 35 includes a small turbine 35T (first turbine), and the small compressor chamber 36 includes a small compressor 36B (first compressor). The small turbine 35T and the small compressor 36B are connected by a small turbine shaft 38 (first turbine shaft). The small turbine shaft 38 extends between the small turbine chamber 35 and the small compressor chamber 36, and the small turbine 35T is attached to one end of the small turbine shaft 38, and the small compressor 36B is attached to the other end. The small turbine 35T receives the kinetic energy of the exhaust and rotates around the small turbine shaft 38. The small compressor 36B also rotates around the small turbine shaft 38 to compress (supercharge) the intake air. When the small turbine 35T rotates upon receiving the kinetic energy of the exhaust, the small compressor 36B also rotates integrally around the small turbine shaft 38. In the present embodiment, a so-called FGT (Fixed Geometry Turbocharger) in which the flow rate of the inflowing exhaust gas cannot be changed is used as the small turbine 35T.

  The capacity of the large turbine 33T is larger than the capacity of the small turbine 35T, and the capacity of the large compressor 34B is set larger than the capacity of the small compressor 36B. As a result, the large turbo unit 3A can rotate the large turbine 33T by exhaust gas having a larger flow rate than the small turbo unit 3B, and can supercharge intake air having a larger flow rate by rotation of the large compressor 34B.

  The turbocharger 3 is provided with a supercharger intake passage 44 as a passage that serves as a part of the intake passage P1 within the turbocharger 3. The supercharger intake passage 44 includes an intake introduction passage 45, an inter-compressor passage 46, a downstream passage 47, an outlet passage 48, and an intake bypass passage 49. The intake intake passage 45 is the most upstream intake passage in the turbocharger 3 and is a passage from the axial direction of the large turbine shaft 37 toward the large compressor 34 </ b> B in the large compressor chamber 34.

  A blow-by recirculation passage 411 that joins the blow-by gas to the intake passage P <b> 1 is connected to the intake introduction passage 45. That is, the blow-by recirculation path 411 is connected to the upstream side of the large compressor chamber 34 in the intake passage P1. For this reason, in the present embodiment, if there is a portion where the flow of the intake air is disturbed in the intake passage P1 on the downstream side of the blow-by return passage 411, there is a possibility that the oil component of blow-by accumulates in the portion.

  The inter-compressor passage 46 is a passage that guides intake air from the scroll portion (large scroll portion 315) on the outer periphery of the large compressor 34B toward the axis of the small compressor 36B in the small compressor chamber 36. The first coupling portion 316, the second coupling portion 323, and the cold decoupler 317 described above form a part of the intercompressor passage 46.

  The downstream passage 47 is a passage from the scroll portion (small scroll portion 324) on the outer periphery of the small compressor 36B toward the outlet passage 48. The outlet passage 48 is the most downstream intake passage in the turbocharger 3 and is a passage connected to the intercooler 42. As described above, in the intake passage P1, the large compressor 34B (large compressor chamber 34) is arranged on the upstream side of the small compressor 36B (small compressor chamber 36).

  The intake bypass passage 49 is a passage that bypasses the small compressor chamber 36, that is, a passage that guides intake air downstream without supplying intake air to the small compressor 36B. Specifically, the intake bypass passage 49 branches from the middle of the intercompressor passage 46 connecting the large compressor chamber 34 and the small compressor chamber 36, and merges with the outlet passage 48 together with the downstream passage 47. An intake bypass valve 491 that opens and closes the passage 49 is disposed in the intake bypass passage 49. The downstream housing 325 described above is a housing that mainly partitions the downstream passage 47 and the intake bypass passage 49.

  In a state where the intake bypass valve 491 is fully closed and the intake bypass passage 49 is closed, the entire amount of intake air flows into the small compressor chamber 36. On the other hand, when the intake bypass valve 491 is open, most of the intake air bypasses the small compressor chamber 36 and flows downstream through the intake bypass passage 49. That is, since the small compressor 36B accommodated in the small compressor chamber 36 becomes resistant to the flow of intake air, most of the intake air has a smaller resistance when the intake bypass valve 491 is open. It flows into the passage 49. The intake bypass valve 491 is opened and closed by a negative pressure type valve actuator 492.

  The turbocharger 3 is provided with a supercharger exhaust passage 50 as a passage serving as a part of the exhaust passage P2 in the turbocharger 3. The supercharger exhaust passage 50 includes an exhaust introduction passage 51, a communication passage 52, a small scroll passage 53, an inter-turbo passage 54, a large scroll passage 55, a discharge passage 56 and an exhaust bypass passage 57. The exhaust introduction passage 51, the communication passage 52 and the small scroll passage 53 are passages formed in the small turbine case 32T, the large scroll passage 55 and the discharge passage 56 are passages formed in the large turbine case 31T, the inter-turbo passage 54 and The exhaust bypass passage 57 is a passage formed across both cases 31T and 32T. In the present embodiment, the small turbine 35T (that is, the small turbine chamber 35) is disposed on the upstream side of the large turbine 33T (that is, the large turbine chamber 33) in the exhaust passage P2.

  The exhaust introduction passage 51 is the most upstream exhaust passage in the turbocharger 3 and is a passage that receives exhaust from the engine body 10 side. The communication passage 52 is a passage that continues downstream of the exhaust introduction passage 51 and guides the exhaust toward the small turbine chamber 35. The small scroll passage 53 forms a part of the small turbine chamber 35, and is a passage that guides exhaust toward the small turbine 35T. The downstream end of the communication passage 52 is connected to the upstream portion of the small scroll passage 53. The small scroll passage 53 is a spiral passage disposed so as to circulate around the outer periphery of the small turbine 35T, and the flow path width gradually decreases toward the downstream. The exhaust gas flows from the small scroll passage 53 toward the radial center of the small turbine 35T, and rotates the small turbine 35T around the small turbine shaft 38.

  The inter-turbo passage 54 is a passage connecting the small turbine 35 </ b> T and the upstream portion of the large scroll passage 55. The upstream portion of the inter-turbo passage 54 is a portion that extends from the small turbine chamber 35 in the axial direction of the small turbine 35 </ b> T, and the downstream portion is a portion that continues to the upstream portion of the large scroll passage 55. Exhaust gas that has flowed radially inward from the outer periphery of the small turbine 35T and has performed expansion work on the small turbine 35T is taken out from the inter-turbo passage 54 and travels toward the large turbine 33T.

  The large scroll passage 55 forms a part of the large turbine chamber 33, and is a passage that guides exhaust toward the large turbine 33T. The large scroll passage 55 is a spiral passage disposed so as to go around the outer periphery of the large turbine 33T, and the flow passage width gradually narrows toward the downstream. The exhaust gas flows from the large scroll passage 55 toward the radial center of the large turbine 33T, and rotates the large turbine 33T around the large turbine shaft 37. The exhaust passage 56 is the most downstream exhaust passage in the turbocharger 3, and extends from the large turbine chamber 33 in the axial direction of the large turbine 33T. Exhaust gas that has flowed radially inward from the outer periphery of the large turbine 33T and has performed expansion work on the large turbine 33T is taken out from the discharge passage 56. The downstream end of the discharge passage 56 is an opening provided in the exhaust-side flange portion 313 and is connected to the exhaust passage that reaches the exhaust purification device 70 downstream.

  The exhaust bypass passage 57 is a passage that bypasses the small turbine chamber 35, that is, a passage that guides exhaust gas downstream (large turbine 33T) without causing exhaust to act on the small turbine 35T. Specifically, the exhaust bypass passage 57 branches from between the exhaust introduction passage 51 and the communication passage 52 and joins the upstream portion of the large scroll passage 55 to bypass the small scroll passage 53 and the inter-turbo passage 54. ing. An exhaust bypass valve 6 that opens and closes the passage 57 is disposed in the exhaust bypass passage 57. The exhaust bypass valve 6 includes a valve body 61 that actually opens and closes the exhaust bypass passage 57, and a valve actuator 6A that operates the valve body 61.

  When the exhaust bypass valve 6 (valve body 61) is fully closed and the exhaust bypass passage 57 is closed, the entire amount of exhaust gas flows into the small turbine chamber 35. When the EGR device 80 is operated and the EGR gas is recirculated, the entire amount of the gas excluding the EGR gas from the exhaust discharged from the engine body 10 flows into the small turbine chamber 35. On the other hand, in a state where the exhaust bypass valve 6 is open, most of the exhaust gas bypasses the small turbine chamber 35 and flows into the large turbine chamber 33 (large scroll passage 55) on the downstream side. That is, since the small turbine 35T accommodated in the small turbine chamber 35 becomes resistant to the flow of exhaust, in the state where the exhaust bypass valve 6 is open, most of the exhaust is an exhaust bypass having a smaller resistance. It flows into the passage 57. That is, the exhaust gas flows downstream without passing through the small turbine 35T.

  In other words, no matter how the exhaust bypass valve 6 operates, the exhaust always passes through the large turbine 33T of the large turbine chamber 33. That is, since the large turbo unit 3A can always operate to perform supercharging of intake air, the supercharging pressure of intake air by the turbo supercharger 3 can be increased, and the energy efficiency of the entire engine system can be increased. .

[Operation of turbocharger]
The turbocharger 3 supercharges intake air in cooperation with the small turbo unit 3B and the large turbo unit 3A in the low speed rotation region of the engine body 10, and large in the medium to high speed rotation region of the engine body 10. The turbo unit 3A supercharges intake air.

  The exhaust bypass valve 6 is fully closed when the engine body 10 is operating in the low speed rotation region, and exhaust is supplied to the small turbine 35T through the communication passage 52 and the small scroll passage 53. Since the inertia of the small turbine 35T is small, even if the exhaust gas flow rate is small, the rotational speed increases early, and the supercharging force by the small compressor 36B can be increased. Thereafter, the exhaust gas passes through the inter-turbo passage 54 and the large scroll passage 55 and is supplied to the large turbine 33T. That is, both the large turbine 33T and the small turbine 35T rotate in the low-speed rotation region, and accordingly, the large compressor 34B and the small compressor 36B also rotate. Accordingly, both the large turbo unit 3A and the small turbo unit 3B operate and can supercharge intake air.

  At this time, the opening degree of the variable vane mechanism 39 attached to the large turbine 33T is set small. That is, the control device (not shown) controls the VGT actuator 39A to rotate the nozzle vane (not shown) by a predetermined angle so that the exhaust passage area is reduced. Thereby, the flow velocity of the exhaust gas flowing into the large turbine 33T is increased, and the supercharging force by the large compressor 34B in the low speed rotation region can be increased.

  On the other hand, when the engine body 10 is operating in the medium speed to high speed rotation region, the exhaust bypass valve 6 is fully opened, and the exhaust is supplied exclusively to the large turbine 33T through the exhaust bypass passage 57. That is, since the exhaust flow resistance can be suppressed as much as possible and exhaust can be supplied to the large turbine 33T, energy efficiency can be improved. At this time, the nozzle vane opening degree of the variable vane mechanism 39 is a basic vane opening degree for obtaining a predetermined supercharging pressure set in advance.

  The valve actuator 6A is composed of an electric actuator device. The valve actuator 6A can not only simply open and close the valve body 61 but also adjust the opening degree of the valve body 61 between fully closed and fully opened. The opening degree of the valve body 61 is set so that the supercharging pressure becomes a target pressure for each operating condition. The target boost pressure and the opening degree of the valve body 61 are set in advance by the engine speed and the engine load. The valve actuator 6A controls the opening degree of the valve body 61 according to the setting.

  Next, the flow of intake air will be described. 6 shows the intake air flow in the turbocharger 3 in the low speed rotation region, and FIG. 7 shows the intake air flow in the turbocharger 3 in the medium to high speed rotation region. It is a perspective view. In the low speed rotation region, as indicated by the arrow F0 in FIG. 6, the intake air enters the large compressor case 31C (large compressor chamber 34) through the intake inlet 45A. The flow direction of the intake air at this time is a direction toward the rotating shaft (large turbine shaft 37) of the large compressor 34B.

  When the large compressor 34B rotates around the axis in conjunction with the large turbine 33T, the intake air is supercharged. As indicated by the arrow F1, the intake air scrolls around the outer periphery of the large compressor 34B in the large scroll portion 315 and then flows downward and flows into the small compressor case 32C through the cold decoupler 317. Thereafter, as indicated by an arrow F21, the intake air enters the small compressor chamber 36 toward the rotation shaft (small turbine shaft 38) of the small compressor 36B, and is supercharged by the small compressor 36B. Subsequently, the intake air passes through the small scroll portion 324 on the outer periphery of the small compressor 36 </ b> B and travels toward the downstream housing 325. Then, as indicated by an arrow F3, the intake air is discharged to the outside of the turbocharger 3 through the intake discharge port 48A of the intake discharge flange portion 326.

  In the medium to high speed range, the intake bypass valve 491 is fully closed and the intake bypass passage 49 is closed, so that the intake flow path is different from the low speed rotation range after entering the small compressor chamber 36. Become. That is, in FIG. 7, the paths indicated by arrows F0 and F1 are the same as those in FIG. However, after entering the small compressor case 32C, as indicated by an arrow F22, the intake air does not go to the small compressor chamber 36 but passes through the intake bypass passage 49 in the downstream housing 325. And as shown by the arrow F3, intake air is discharged outside the turbocharger 3 through the intake discharge port 48A.

[Arrangement of passage between turbine shaft and compressor]
FIG. 8 is a side view of the turbocharger 3 according to this embodiment as viewed from the large and small compressor cases 31C and 32C (large and small compressor chambers 34 and 36), and FIG. 9 is equipped with a turbocharger. 1 is a schematic top view of an engine 1 (plan view in the axial direction of a cylinder 2). As shown in FIG. 8, the large compressor case 31C that defines the upstream large compressor chamber 34 in the intake passage is disposed above the small compressor case 32C that defines the downstream small compressor chamber 36. . The inter-compressor passage 46 extends substantially linearly in the vertical direction in the side view. As shown in FIG. 8, the engine body 10 is located on the left side of the turbocharger 3 (large turbo part 3 </ b> A) in a side view from the compressor case side. In addition, the left-right direction display attached | subjected to FIG. 8 has shown the left-right direction in the side view from the compressor case side, and the left-right direction is displayed contrary to the direction display of FIG.

  As shown in FIG. 9, an intake air intake pipe 40 is connected to the large compressor case 31 </ b> C of the turbocharger 3. The intake air intake pipe 40 is a pipe member that connects an air cleaner 41 (FIG. 5) and an intake air inlet 45A (FIGS. 3 and 4) provided at the rear end of the large compressor case 31C. The intake intake pipe 40 extends from right to left along the vicinity of the rear side of the engine body 10, a downstream portion thereof is curved forward, and a most downstream end is coupled to the intake introduction port 45 </ b> A. As indicated by an arrow F0 in the figure, the intake air purified by the air cleaner 41 is supplied to the large compressor case 31C through the intake air introduction pipe 40.

  The arrangement direction of the four cylinders 2 arranged in series in the engine body 10 is the front-rear direction of the engine body 10, and the engine output shaft (crankshaft 23) also extends in the front-rear direction. FIG. 9 shows a straight line L1 (hereinafter referred to as the engine output shaft L1) corresponding to the extending direction of the engine output shaft. The engine body 10 has a rectangular shape that is generally long in the front-rear direction when viewed from above. The arrangement position of the turbocharger 3 is a position adjacent to the left side surface 10L of the engine body 10 and in the vicinity of the rear side surface 10B.

  In FIG. 9, the large turbine chamber 33 and the large compressor chamber 34 of the large turbo unit 3A, the large turbine shaft 37 extending between these chambers, the small turbine chamber 35 and the small compressor chamber 36 of the small turbo unit 3B, A small turbine shaft 38 extending between the two chambers is schematically depicted. Furthermore, a straight line L2 corresponding to the axis line of the large turbine shaft 37 and a straight line L3 corresponding to the axis line of the small turbine shaft 38 are respectively drawn (hereinafter referred to as the large turbo shaft L2 and the small turbo shaft L3). The large turbo shaft L2 and the small turbo shaft L3 extend in the front-rear direction in the same manner as the engine output shaft L1. FIG. 9 shows an example in which the large turbo shaft L2 and the small turbo shaft L3 are parallel to the engine output shaft L1, but at least one of the large and small turbo shafts L2, L3 is inclined with respect to the engine output shaft L1. Such an arrangement, or an arrangement in which the large and small turbo shafts L2 and L3 intersect within the large and small turbine shafts 37 and 38 or outside the axial range may be used.

  In the positional relationship between the large turbine shaft 37 and the small turbine shaft 38 and the engine output shaft L1, in the plan view in the axial direction of the cylinder 2, the large turbine shaft 37 is farther from the engine output shaft L1 than the small turbine shaft 38. Is arranged. In other words, referring to FIG. 8, the small turbine shaft 38 is disposed on the side close to the left side surface 10 </ b> L of the engine body 10, and the large turbine shaft 37 is separated to the right from the small turbine shaft 38. The large turboshaft L2 that is the center of the large turbine shaft 37 and the small turboshaft L3 that is the center of the small turbine shaft 38 are spaced apart from each other in the vertical direction, and are also separated from each other by a predetermined distance in the left-right direction. The large turbo part 3 </ b> A and the small turbo part 3 </ b> B are arranged with respect to the engine body 10 so that the positional relationship between the large turbine shaft 37 and the small turbine shaft 38 is satisfied.

  In the side view of FIG. 8, the large turbine shaft 37 rotates counterclockwise (arrow a in the figure) around the axis. This means that the scroll direction from upstream to downstream of the large scroll portion 315 is also counterclockwise. A downstream end 315E (exit of the second compressor chamber) of the large scroll portion 315 opens downward on the left side of the large turbine shaft 37. On the other hand, the inlet 324A (the inlet of the first compressor chamber) to the small compressor chamber 36 is arranged on the small turbo shaft L3. The downstream end 315E and the inlet 324A have a positional relationship that is linearly aligned in the vertical direction by the amount that the large turbo shaft L2 is shifted to the right with respect to the small turbo shaft L3.

  The inter-compressor passage 46 is an intake passage from the downstream end 315 </ b> E that is the outlet of the large compressor chamber 34 to the inlet 324 </ b> A of the small compressor chamber 36. The inter-compressor passage 46 includes a straight portion 461 extending linearly downward from the downstream end 315E, and a bent portion 462 connecting the downstream end of the straight portion 461 and the inlet portion 324A. The straight portion 461 includes the first coupling portion 316, the second coupling portion 323, and the cold decoupler 317, the first coupling portion 316S that connects the first coupling portion 316 and the downstream end 315E, and the second cup. It consists of the 2nd connection part 323S which connects the ring part 323 and the bending part 462. FIG.

  As shown in FIG. 3, the first connecting portion 316 </ b> S is a path that is gently curved in the front-rear direction, but is located vertically above the first coupling portion 316 in the side view shown in FIG. 8. Yes. The first coupling unit 316, the second coupling unit 323, the cold decoupler 317, and the second coupling unit 323S are also arranged in the vertical direction. That is, the straight portion 461 is a straight passage that extends in a substantially vertical direction in the side view unless the engine 1 is slanted. The bent portion 462 is a passage curved in three dimensions so as to change the direction of the intake passage from the straight portion 461 extending in the vertical direction to the horizontal direction in which the small turbo shaft L3 extends, and is positioned immediately upstream of the small compressor 36B. Yes.

  Such an intercompressor passage 46 is disposed closer to the engine body 10 than the large turbine shaft 37 in a side view shown in FIG. That is, the inter-compressor passage 46 is disposed between the left side surface 10L of the engine body 10 and the large turbine shaft 37 in the left-right direction, and linearly connects the large compressor case 31C and the small compressor case 32C.

[Turbo shaft center distance]
Next, in the side view of FIG. 8, a preferable distance between the shaft centers in the left-right direction between the large turbo shaft L2 of the large turbine shaft 37 and the first turbo shaft of the small turbine shaft 38 will be described. 10 and 11 are schematic views showing the arrangement relationship between the large and small turbo shafts L2 and L3, and the large and small turbine shafts 37 and 38 (large and small turbo shafts L2,. L3).

From the viewpoint of downsizing the turbocharger 3 and ensuring the linearity of the passage 46 between the compressors, the distance A between the shaft centers of the large and small turbo shafts L2 and L3 is outside the large compressor 34B (second compressor). When the diameter is B,
B / 2 ≦ A ≦ B (1)
It is preferable to set in the range.

  FIG. 10 shows a case where the distance between the shaft centers A = B / 2, that is, when the small turbo shaft L is shifted to the left with respect to the large turbo shaft L2 by the length of the radius of the large compressor 34B. An embodiment of the intercompressor passage 46 is shown. As in the example of FIG. 8, the inter-compressor passage 46 in this case has a large portion extending downward from the downstream end 315E as a straight passage (straight portion 461) in the vertical direction, and is curved in the vicinity of the inlet portion 324A ( A bent passage 462) can be formed. If the distance A between the axes is smaller than B / 2, it is necessary to increase the degree of bending in the left-right direction at the bent portion 462, which is not preferable.

  FIG. 11 shows the distance between the compressors when the distance between the shaft centers is set to A = B, that is, when the small turboshaft L is shifted to the left with respect to the large turboshaft L2 by the length of the diameter of the large compressor 34B. One aspect of the passage 46 is shown. In this case, for example, the inter-compressor passage 46 can be a passage that gently curves in the left-right direction at the upstream portion corresponding to the extended portion from the downstream end 315E, is linear in the up-down direction at the downstream portion, and is connected to the bending portion 462. . If the distance A between the axes is greater than B, for example, it is necessary to increase the degree of bending in the left-right direction at the upstream portion of the intercompressor passage 46, which is not preferable.

[Function and effect]
The turbocharged engine 1 according to this embodiment described above has the following operational effects. The turbocharger 3 is a two-stage turbocharger including a large turbo part 3A and a small turbo part 3B. The large compressor chamber 34 of the large turbo unit 3A is disposed upstream of the small compressor chamber 36 of the small turbo unit 3B in the intake passage P1. For this reason, the inter-compressor passage 46 opens in the axial direction of the small turbine shaft 38 and the downstream end 315E (exit of the large compressor chamber 34) of the large scroll portion 315 existing around the large turbine shaft 37. The inlet 324A of the compressor chamber 36 is connected. Further, since the large turbine shaft 37 is disposed on the side farther than the small turbine shaft 38 with respect to the engine output shaft L1, according to a side view viewed from the large and small compressor chambers 34 and 36, the small turbine shaft 38 is provided. Exists at a position shifted to the left side of the large turbine shaft 37.

  Assuming the above configuration, the large turbine shaft 37 rotates counterclockwise around its axis, so the position of the downstream end 315E of the large scroll portion 315 is set to the position of the inlet portion 324A of the small compressor chamber 36 in the left-right direction. It becomes easy to match. That is, the downstream end 315E and the inlet portion 324A are likely to be in a positional relationship that is substantially linearly aligned in the vertical direction.

  In addition, since the compressor-to-compressor passage 46 is disposed closer to the engine body 10 than the large turbine shaft 37, the compressor-to-compressor passage 46 can be a passage that does not naturally need to be curved in the side view. . For this reason, the compressor passage 46 can be a simple and compact passage. Further, in the portion near the inlet portion 324A of the intercompressor passage 46, the intake passage needs to be curved three-dimensionally so that the passage extending in the vertical direction is directed in the horizontal direction in which the small turbine shaft 38 extends. In this embodiment, it is easy to set the curve of the passage with a sufficiently large bend R. Therefore, unevenly distributed flow or the like does not occur in the intake air flowing through the intercompressor passage 46, and the intake resistance can be suppressed to a low level, and the supercharging efficiency can be increased.

  Further, since the distance A between the axial centers of the large and small turbine shafts 37 and 38 (large and small turbo shafts L2 and L3) in the left-right direction is set in the range of the above expression (1), the inlet portion of the small compressor chamber 36 324A is not too far away from the large turbine shaft 37 in the left-right direction. Accordingly, the inter-compressor passage 46 can be a passage with less curvature in the side view.

  Further, in the side view, the intercompressor passage 46 includes a straight portion 461 extending linearly from the downstream end 315E of the large scroll portion 315, a downstream end of the straight portion 461, and an inlet portion 324A of the small compressor chamber 36. And a bending portion 462 to be connected. Accordingly, the intercompressor passage 46 can be formed by the straight portion 461 except for the bent portion 462 in the vicinity of the inlet portion 324A. Further, the bending portion 462 does not have to be an excessively curved shape that increases the intake resistance. Accordingly, the intake resistance in the intercompressor passage 46 can be kept low.

  In the present embodiment, the blow-by return path 411 is connected to the upstream side of the large compressor chamber 34 in the intake passage P1. For this reason, blow-by oil may accumulate in the intake passage P1. For example, the intake air discharged from the large scroll part 315 passes through the inter-compressor passage 46 while forming a swirl flow. Cause deposition. However, in this embodiment, since the intake resistance of the inter-compressor passage 46 disposed on the downstream side of the blow-by recirculation passage 411 is low, it is possible to prevent the oil from being accumulated.

  As described above, according to the present invention, in the engine 1 provided with the two-stage turbocharger 3 having the large and small turbo parts 3A and 3B, the intake air in the intercompressor passage 46 of the turbocharger 3 is provided. Flow resistance can be reduced. Thereby, the pressure loss of the intake air is suppressed, and the supercharging efficiency of the turbocharger 3 can be improved.

[Description of Modified Embodiment]
Although one embodiment of the present invention has been described above, the present invention is not limited to this. In the above-described embodiment, the example in which the inter-compressor passage 46 includes the straight portion 461 and the bent portion 462 is shown. Alternatively, the inter-compressor passage 46 may be a passage that is loosely curved, for example, generally bowed.

  FIG. 12 is a side view of the turbocharger 30 according to the modified embodiment as viewed from the compressor chamber side. The intercompressor passage 46A provided in the turbocharger 30 is an arcuate curved passage that connects the downstream end 315E of the large scroll portion 315 and the inlet portion 324A of the small compressor chamber 36. The inter-compressor passage 46A is gently curved leftward between the downstream end 315E and the inlet 324A, and is closest to the engine body 10 in the vicinity of the middle in the vertical direction. In this way, the intake resistance in the inter-compressor passage 46A can be kept low even if the inter-compressor passage 46A is an arcuate curved passage, that is, a generally gently curved passage.

  In addition, the rotation direction of the small turbine shaft 38 is shown in FIGS. 8 and 12 as being counterclockwise as in the case of the large turbine shaft 37, but is rotated in the clockwise direction opposite to the large turbine shaft 37. You may make it let it. Moreover, the turbocharger 3 provided with the large turbo part 3A and the small turbo part 3B was illustrated as a two-stage turbocharger. Alternatively, the two turbo units may be a two-stage turbocharger having the same supercharging capability.

1 Engine with turbocharger 10 Engine body 2 Cylinder 23 Crankshaft (engine output shaft)
3 Turbocharger 3A Large turbo part (second turbo part)
3B Small turbo part (1st turbo part)
33 Large turbine room (second turbine room)
33T Large turbine (second turbine)
34 Large compressor room (second compressor room)
34B Large compressor (second compressor)
35 Small turbine room (1st turbine room)
35T small turbine (1st turbine)
36 Small compressor room (first compressor room)
36B Small compressor (first compressor)
37 Large turbine shaft 38 Small turbine shaft 315E Downstream end (outlet of second compressor chamber)
324A inlet (inlet of the first compressor chamber)
46, 46A Compressor passage 461 Straight section 461
462 Bending part 462
P1 Intake passage P2 Exhaust passage L1 Engine output shaft L2 Large turbo shaft L3 Small turbo shaft

Claims (5)

An engine body having a cylinder and an engine output shaft;
A turbocharger that is disposed adjacent to the engine body, has an exhaust passage through which exhaust is supplied from the engine body, and an intake passage through which intake air is supplied to the engine body;
The turbocharger is
A first turbine chamber with a built-in first turbine communicating with the exhaust passage, a first compressor chamber with a built-in first compressor communicating with the intake passage, and the first turbine and the first compressor extending between the two chambers A first turbo part including a first turbine shaft that couples
A second turbine chamber containing a second turbine communicating with the exhaust passage, a second compressor chamber containing a second compressor communicating with the intake passage, and the second turbine and the second compressor extending between the two chambers. A second turbo part including a second turbine shaft connecting the two,
An inlet of the first compressor chamber is disposed on an axis of the first turbine shaft;
The second compressor chamber is disposed upstream of the first compressor chamber in the intake passage, and has a scroll portion that forms a spiral intake passage around the second compressor,
The first turbine shaft and the second turbine shaft are arranged to extend substantially in the same direction as the engine output shaft,
In the turbocharged engine in which the second turbine shaft is disposed farther than the first turbine shaft with respect to the engine output shaft in a plan view in the axial direction of the cylinder,
In a side view of the first and second turbine shafts as viewed from the first and second compressor chambers,
The upstream side of the scroll portion is a direction away from the first turbine chamber from a side farther from the second turbine shaft than the engine body in the left-right direction, and a direction gradually approaching the engine body. Scroll to
The downstream side of the scroll portion is scrolled in a direction toward the first turbine shaft arranged closer to the engine body in the left-right direction than the second turbine shaft while approaching the engine body. And
The downstream end of the scroll portion is an outlet of the second compressor chamber, and the outlet opens in a direction perpendicular to the second turbine shaft and toward the first turbine shaft,
The compressor passage from the outlet of the second compressor chamber to the inlet of the first compressor chamber is disposed closer to the engine body than the second turbine shaft. From the outlet of the second compressor chamber, the scroll Extending in the tangential direction of the downstream end of the section and extending in the direction toward the first turbine axis,
This is a turbocharged engine. In the turbocharged engine according to claim 1,
In the side view, the axis distance A between the right and left direction between the second turbine shaft and the first turbine shaft, when the outer diameter of the second compressor is B,
B / 2 ≦ A ≦ B
The turbocharged engine that is set in the range of The turbocharged engine according to claim 1 or 2,
In the side view, the passage between the compressors is
A straight portion extending linearly from the downstream end of the scroll portion of the second compressor chamber;
A turbocharged engine comprising: a bent portion that connects a downstream end of the straight portion and an inlet portion along the first turbine axis of the first compressor chamber. The turbocharged engine according to claim 1 or 2,
In the side view, the intercompressor passage is an arcuate curved passage that connects the downstream end of the scroll portion of the second compressor chamber and the inlet portion along the first turbine shaft of the first compressor chamber. , Turbocharged engine. The turbocharged engine according to claim 1 or 2,
An engine with a turbocharger, wherein a blow-by recirculation passage for connecting blow-by gas to the intake passage is connected upstream of the second compressor chamber in the intake passage.