JP5974802B2 - Turbocharger for multi-cylinder engine - Google Patents

Description

  The present invention relates to a turbocharger provided in a multi-cylinder engine, and more particularly to a turbocharger with improved assemblage to the engine.

  2. Description of the Related Art Conventionally, a turbocharger that uses exhaust energy to increase engine output has been provided in a turbine wheel provided in an exhaust passage (hereinafter sometimes abbreviated as “turbine”) and an intake passage. A compressor wheel (hereinafter sometimes abbreviated as “compressor”) is connected to a connecting shaft, and the turbine is driven by the exhaust gas pressure to drive the compressor and compress the intake air. To raise.

  In Patent Documents 1 and 2, the axial direction of the turbocharger is arranged so as to be the cylinder row direction of the multi-cylinder engine. In the cylinder row direction of the engine, the center of the cylinder row length of the engine and the exhaust manifold A turbocharger is disclosed in which the center of the collecting portion coincides with the center of the turbine inlet of the turbocharger. According to this, the exhaust passages of each cylinder are made equal in length and volume, and dynamic pressure exhaust performance such as ejector effect is improved.

JP 2009-97404 A JP 2009-103041 A

  By the way, as shown in FIG. 12A, the turbine, the compressor, and the connecting shaft of the turbocharger are accommodated in the turbine housing t, the compressor housing c, and the center housing s, respectively. The housing c is connected via the center housing s. Since the connecting shaft has a smaller diameter than the turbine and the compressor, the center housing s has a smaller diameter than the turbine housing t and the compressor housing c. Therefore, a space sandwiched between the turbine housing t and the compressor housing c is formed outside the center housing s in the radial direction. When the turbocharger is assembled on the engine body side, the assembly work can be performed using the space. FIG. 12A shows a case where the engine body side is viewed from the turbocharger side.

  For example, an exhaust introduction passage e for introducing exhaust from the engine body side into the turbine may be provided integrally with the turbine housing t. The exhaust introduction passage e extends from the turbine housing t toward the engine body. An assembly flange f is provided at the end of the exhaust introduction passage e on the engine body side, and the turbocharger is assembled to the engine body via the assembly flange f.

  For example, a turbocharger is provided by providing a plurality of bolt insertion holes v1 to v4 in the assembly flange f, inserting stud bolts attached to the engine body side into these bolt insertion holes v1 to v4, and tightening with nuts. The machine can be assembled on the engine body side. In this assembly, when the engine body side is viewed from the turbocharger side, in the case of the figure, the upper right bolt insertion hole v1 is located between the turbine housing t and the compressor housing c outside the center housing s in the radial direction. Located in the space created. Therefore, the turbocharger can be assembled by inserting a finger or a tool into the space from the turbocharger side with respect to the bolt insertion hole v1.

  The symbol x is the center of the cylinder row length in the cylinder row direction on the engine body side (hereinafter sometimes referred to as “engine center”), and the symbol y is the axial direction on the turbocharger side. Is the outlet of the exhaust introduction passage e, that is, the center of the inlet of the turbine (hereinafter may be abbreviated as “turbine center”). The engine center x and the turbine center y coincide.

  Here, the exhaust introduction passage e collects exhaust gases discharged from a plurality of cylinders of the multi-cylinder engine and introduces them into the turbine. Therefore, as shown in FIG. May be widened. Then, the assembly flange f provided at the end of the exhaust introduction passage e on the engine body side also extends in the cylinder row direction, and the bolt insertion hole v1 is hidden behind the compressor housing c. Therefore, the turbocharger cannot be assembled to the bolt insertion hole v1, the number of fastening members such as bolts and nuts is reduced, and the support rigidity of the turbocharger is weakened.

  Therefore, the present invention provides a space generated between the turbine housing and the compressor housing outside in the radial direction of the center housing even when the engine body side of the exhaust introduction passage integrally provided in the turbine housing is widened in the cylinder row direction. An object of the present invention is to provide a turbocharger for a multi-cylinder engine in which a turbocharger can be assembled to the engine body side using the above.

That is, the present invention provides a turbine housing that houses a turbine wheel provided in an exhaust passage, a compressor housing that contains a compressor wheel provided in an intake passage, and a connecting shaft that connects the turbine wheel and the compressor wheel. A turbocharger for a multi-cylinder engine in which the turbocharger is arranged such that an axial direction of a turbocharger including a center housing for accommodating the turbocharger coincides with a cylinder row direction of the engine, the turbine housing The turbocharger is provided at an end of the exhaust gas introduction passage extending from the engine main body side to the turbine wheel and introducing an exhaust gas from the engine main body side into the turbine wheel. And an assembly part for assembling the engine on the engine body side. A mounting portion for a fastening member used when the turbocharger is assembled to the engine main body side is provided, and the engine main body side of the exhaust introduction passage is widened in the cylinder row direction and widened in the direction opposite to the non-compressor side. it is, and, with respect to the center of the cylinder bank length in the cylinder row direction of the engine body side, and the center of the outlet the is the turbine wheel side of the opening of the exhaust introduction passage is biased to the compressor side, the exhaust introduction The passage is partitioned into a high-speed exhaust introduction passage through which exhaust gas flows only when the engine rotational speed is equal to or higher than a predetermined reference rotational speed, and a low-speed exhaust introduction passage through which exhaust gas constantly flows regardless of the engine rotational speed, The low-speed exhaust introduction passage is disposed radially inside the turbine with respect to the high-speed exhaust introduction passage, and the exhaust gas flow area of the low-speed exhaust introduction passage is the high-speed exhaust passage. The length of the low-speed exhaust introduction passage in the cylinder row direction is set to be shorter than the length of the high-speed exhaust introduction passage in the cylinder row direction so that the value is smaller than the exhaust gas flow area of the introduction passage. The turbocharger for a multi-cylinder engine is characterized in that at least the engine main body side of the low-speed exhaust introduction passage is widened in a non-compressor side (claim 1).

  According to the present invention, the engine main body side of the exhaust introduction passage integrally provided in the turbine housing is widened toward the anti-compressor side, and the center of the cylinder row length in the cylinder row direction on the engine main body side (that is, the engine center) ), The center of the outlet of the exhaust introduction passage in the axial direction on the turbocharger side (that is, the turbine center) is biased toward the compressor side in the axial direction. As shown in FIG. 13, the attached portion of the fastening member (for example, the bolt insertion hole v <b> 1 in FIG. 12B) that is hidden behind the compressor housing c when it is widened to the same level on the compressor side and the non-compressor side. And located in a space formed between the turbine housing t and the compressor housing c outside the center housing s in the radial direction. .

  Therefore, the turbocharger can be assembled by inserting a finger or a tool into the space from the turbocharger side with respect to the attached portion. That is, the turbocharger can be assembled on the engine body side using the space. As a result, a reduction in the number of fastening members such as bolts and nuts is avoided, and the support rigidity of the turbocharger is ensured.

Moreover , the exhaust introduction passage is divided into two for low speed and high speed, and the low speed exhaust introduction passage is arranged on the radial inside of the turbine with respect to the high speed exhaust introduction passage. It is arranged closer to the shaft center in the radial direction than the exhaust introduction passage. Therefore, in particular, when the low-speed exhaust introduction passage is widened to the same extent on the compressor side and the non-compressor side, the possibility that the attached portion of the fastening member is hidden behind the compressor housing increases.

On the other hand , since the low-speed exhaust introduction passage is widened in the direction opposite to the compressor side, the mounted portion that is likely to be hidden behind the compressor housing is again placed in the space between the turbine housing and the compressor housing. Can be positioned. Also, in that case, the exhaust gas distribution area of the low-speed exhaust introduction passage is smaller than the exhaust gas distribution area of the high-speed exhaust introduction passage, so compared to the case where the high-speed exhaust introduction passage is biased toward the non-compressor side, The amount of deviation of the turbine center relative to the engine center is small. Therefore, the equal length and equal volume of the exhaust passage of each cylinder are not greatly impaired, and the improvement of the dynamic pressure exhaust performance such as the ejector effect is ensured.

In the present invention, on the engine body side, a plurality of independent exhaust passages whose upstream ends are connected to exhaust ports of one cylinder or a plurality of cylinders whose exhaust order is not continuous, and downstream ends of the plurality of independent exhaust passages A plurality of low-speed passages and a plurality of high-speed passages connected to the upstream end portion are provided, and the exhaust gas circulation area of the plurality of low-speed passages is smaller than the exhaust gas circulation area of the plurality of high-speed passages And the downstream end portions of the plurality of low speed passages have a throttle shape so as to reduce the exhaust gas flow area, and the low speed exhaust introduction passages communicate with the downstream ends of the plurality of low speed passages, respectively. The high-speed exhaust introduction passage is a common passage that communicates with the downstream ends of the plurality of high-speed passages, and when the engine rotational speed is less than the reference rotational speed, Each cylinder The opening period of the intake valve and the opening period of the exhaust valve overlap with each other by a predetermined overlap period, and the opening of the exhaust valve of each cylinder is started during the overlap period of the other cylinders in the previous exhaust order. (Claim 2 ).

  According to this configuration, in the low speed range where the engine rotation speed is lower than the reference rotation speed, the exhaust gas discharged from the cylinder is separated into the independent exhaust passage and the low speed passage on the engine body side, and the low speed exhaust on the turbocharger side. In the high speed range where the engine rotation speed is higher than the reference rotation speed through the introduction passage, the exhaust gas discharged from the cylinder is an independent exhaust passage on the engine body side, a low speed passage, and a high speed passage. It is introduced into the turbine through the low-speed exhaust introduction passage and the high-speed exhaust introduction passage on the turbocharger side.

  Therefore, in the low speed region, the exhaust gas flow area of the low speed passage and the low speed exhaust introduction passage is small, and therefore the exhaust gas (blowdown gas) discharged immediately after the exhaust valve is opened in the low speed passage and the low speed exhaust. The flow velocity in the introduction passage is increased, and the pressure of the exhaust gas acting on the turbine is increased. That is, the dynamic pressure supercharging effect is strengthened.

  Further, in the low speed region, the flow rate of the blowdown gas in the low speed passage is increased due to the small exhaust gas flow area of the low speed passage, and further, the downstream end of the low speed passage is formed in a throttle shape. The speed of the exhaust gas ejected from the downstream end of the low speed passage to the low speed exhaust introduction passage increases, the negative pressure generated in the low speed exhaust introduction passage increases, and the scavenging of the residual gas in the cylinder is promoted. The That is, the ejector effect is strengthened.

  In that case, since negative pressure acts during the overlap period of the intake valve and the exhaust valve, a blow-through flow is generated from the intake port of the cylinder to the exhaust port, and the amount of gas sucked out by the ejector effect, and thus the turbine The amount of gas acting on the turbine increases, and the turbine driving force is increased.

  As described above, the supercharging capability in the engine low speed region is improved, and the engine torque is improved.

In the present invention, the compressor-side wall surface and the non-compressor-side wall surface of the low-speed exhaust introduction passage are inclined from the engine main body side toward the outlet side, and the exhaust gas is ejected from the downstream ends of the plurality of low-speed passages. Gas flows along the compressor-side wall and the non-compressor-side wall, and the center of the flow of exhaust gas ejected from the downstream ends of the plurality of low-speed passages is the center of the outlet of the low-speed exhaust introduction passage. to focus on, it is preferable that the ejection angle of the exhaust gas ejected from the downstream end of the plurality of low-speed path is set (claim 3).

  According to this configuration, the exhaust gas ejected from the downstream ends of the plurality of low speed passages efficiently flows through the low speed exhaust introduction passage and is introduced into the turbine, so that the dynamic pressure supercharging effect and the ejector effect are further enhanced. It is done.

  According to the present invention, the assembling property of the turbocharger in which the engine main body side of the exhaust introduction passage provided integrally with the turbine housing is widened in the cylinder row direction can be improved.

1 is a schematic overall configuration diagram of a multi-cylinder engine according to an embodiment of the present invention. It is sectional drawing which shows the independent exhaust passage in the cylinder head of the said engine, the low speed path in an exhaust manifold, and the low speed exhaust introduction path in a supercharger casing. It is sectional drawing which follows the III-III line of FIG. FIG. 4 is an end view on the cylinder head side of the exhaust manifold taken along line IV-IV in FIG. 3. FIG. 5 is an end view of a turbocharger casing side of an exhaust manifold along the line VV in FIG. 3. FIG. 6 is a cross-sectional view showing a high-speed passage in the exhaust manifold along the line VI-VI in FIG. 5. FIG. 4 is an end view of the turbocharger casing on the exhaust manifold side along the line VII-VII in FIG. 3. FIG. 8 is a cross-sectional view showing a high-speed exhaust introduction passage in the supercharger casing along the line VIII-VIII in FIG. 7. FIG. 8 is a cross-sectional view showing a low-speed exhaust introduction passage in the supercharger casing along the line IX-IX in FIG. 7. It is explanatory drawing of the ejection angle of the exhaust gas which ejects from the downstream edge part of the low speed channel | path to the low speed exhaust introduction channel | path. It is a time chart which shows the opening / closing timing of the intake / exhaust valve of the said engine for every cylinder. It is explanatory drawing of the subject which this invention tends to solve. It is explanatory drawing of an effect | action of this invention.

(1) Configuration FIG. 1 shows a multi-cylinder engine according to an embodiment of the present invention. However, as will become clear later, high-speed passages 22 a, 22 bc, 22 d are shown in the exhaust manifold 20, and a high-speed exhaust introduction passage 32 is shown in the supercharger casing 30. In this embodiment, “upstream” and “downstream” refer to the flow of gas passing therethrough.

  The engine 1 is an in-line four-cylinder four-cycle spark ignition engine that is mounted on a vehicle as a power source for traveling, and includes a turbocharger 50. The turbocharger 50 has a well-known structure, and a turbine 52 provided in the exhaust passage 33 and a compressor 53 provided in the intake passage 10 are connected by a connecting shaft 51. In FIG. 1, the turbine 52 and the compressor 53 are shown separately for the sake of clarity, but in reality, the turbine 52 is provided at one end of one connecting shaft 51 and the compressor 53 is provided at the other end. Is provided. In the vicinity of the installation position of the turbocharger 50, the intake passage 10 and the exhaust passage 33 are actually close to each other, and the turbocharger 50 is interposed therebetween. In the turbocharger 50, when the turbine 52 rotates with the pressure of the exhaust gas We, the compressor 53 is driven to compress the intake air Wi and increase the intake pressure (supercharging pressure).

  Here, as shown in FIG. 7, the turbine 52 of the turbocharger 50 is accommodated in the turbine housing 52 a, the compressor 53 is accommodated in the compressor housing 53 a, and the connecting shaft 51 is accommodated in the center housing 54. The turbine housing 52a, the compressor housing 53a, the center housing 54, and exhaust introduction passages 31 and 32, which will be described later, are integrally coupled to constitute the supercharger casing 30. The turbocharger 50 is arranged so that its axial direction matches the cylinder row direction of the engine 1.

  Returning to FIG. 1, in the intake passage 10, an intercooler 11 that cools the intake air compressed by the compressor 53 is provided downstream of the compressor 53 of the turbocharger 50, and downstream of the intercooler 11 according to the operating state. A throttle valve 12 for adjusting the intake air amount is provided, a surge tank 13 for temporarily retaining the intake air is provided downstream of the throttle valve 12, and an intake manifold 14 for guiding the intake air to each cylinder is provided downstream of the surge tank 13. Is provided.

  The downstream end of the intake manifold 14 is connected to the cylinder head 2. An engine body having a cylinder head 2, a cylinder block (not shown), and an exhaust manifold 20 as main members includes first to fourth cylinders 4a, 4b, 4c, and 4d (referred to collectively as cylinders 4). It is arranged on a straight line. The cylinder 4 has a well-known structure, and an intake port 5 for sucking intake air Wi supplied from the intake manifold 14 into the combustion chamber at an upper portion of a combustion chamber (not shown) defined by a piston, An exhaust port 6 for discharging the exhaust gas generated in the combustion chamber to the independent exhaust passages 16a, 16bc, 16d, an intake valve 7 for opening and closing the intake port 5, and an exhaust valve 8 for opening and closing the exhaust port 6 are provided. ing. A spark plug 9 is provided at the top of the combustion chamber, and a fuel injection valve (not shown) for directly injecting fuel into the combustion chamber is provided at an appropriate position.

  In the present embodiment, intake, compression, expansion, and exhaust strokes are performed at timings shifted by 180 ° CA in the order of the first cylinder 4a → the third cylinder 4c → the fourth cylinder 4d → the second cylinder 4b ( FIG. 11). Note that “° CA” represents the rotation angle (crank angle) of the crankshaft that is the output shaft of the engine.

  The upstream end of the first independent exhaust passage 16a is connected to the exhaust port 6 of the first cylinder 4a, the upstream end of the first branch passage 16b is connected to the exhaust port 6 of the second cylinder 4b, and the third cylinder 4c The upstream end of the second branch passage 16c is connected to the exhaust port 6, and the upstream end of the third independent exhaust passage 16d is connected to the exhaust port 6 of the fourth cylinder 4d. The first branch passage 16b and the second branch passage 16c merge on the downstream side to form a second independent exhaust passage 16bc that is common to the second cylinder 4b and the third cylinder 4c whose exhaust order is not continuous. These passages 16a, 16b, 16c, 16d, and 16bc are formed in the cylinder head 2.

  As shown in FIGS. 2 and 3, in the exhaust passage 33, upstream of the first to third low-speed passages 21 a, 21 bc, 21 d at the downstream ends of the first to third independent exhaust passages 16 a, 16 bc, 16 d. The end portions and the upstream end portions of the first to third high speed passages 22a, 22bc, 22d are connected. These passages 21 a, 21 bc, 21 d, 22 a, 22 bc, 22 d are formed in the exhaust manifold 20. The exhaust manifold 20 is coupled to the cylinder head 2 by first to fifth stud bolts and nuts V1 to V5 described later.

  As shown in FIGS. 4 and 5, the first to third low speed passages 21a, 21bc, 21d and the first to third high speed passages 22a, 22bc, 22d extend along the flow direction of the exhaust gas. It is divided into two upper and lower stages by 20a. The upper first through third low speed passages 21a, 21bc, and 21d are set to have a smaller exhaust gas flow area than the lower first through third high speed passages 22a, 22bc, and 22d.

  As shown in FIG. 2, the downstream ends of the first to third low speed passages 21a, 21bc, and 21d are formed in a throttle shape so that the exhaust gas flow area is reduced. On the other hand, as shown in FIG. 6, the downstream ends of the first to third high-speed passages 22a, 22bc, and 22d are not formed into a throttle shape.

  As shown in FIG. 2, the downstream ends of the first to third low-speed passages 21a, 21bc, 21d are gathered at the center (engine center) B of the cylinder row length in the cylinder row direction on the engine body side. Close to each other. Similarly, as shown in FIG. 6, the downstream end portions of the first to third high speed passages 22a, 22bc, and 22d are also close to each other so as to gather at the engine center B.

  As shown in FIGS. 3 to 6, the exhaust variable valve 23 is provided in the first to third high speed passages 22 a, 22 bc, 22 d. The exhaust variable valve 23 is driven so as to open the first to third high speed passages 22a, 22bc, 22d when the engine rotational speed is equal to or higher than the intercept rotational speed, and to close when the engine rotational speed is lower than the intercept rotational speed. The intercept rotation speed is the engine rotation speed corresponding to the intercept point. The intercept point is a point that exists on the entire load line, and is a point at which the boost pressure by the compressor 53 of the turbocharger 50 reaches a predetermined upper limit value. When the supercharging pressure reaches the upper limit value, control is performed to open the waste gate valve 56 and flow a part of the exhaust gas to the waist passage 55 (bypassing the turbine 52) in order to prevent further increase. . This control may be executed in consideration of not only the engine rotation speed but also the engine load. For example, it can be executed in a low speed range and a high load range.

  As shown in FIGS. 2 and 3, in the exhaust passage 33, the upstream end of the low-speed exhaust introduction passage 31 is connected to the downstream ends of the first to third low-speed passages 21a, 21bc, and 21d. The upstream end of the high-speed exhaust introduction passage 32 is connected to the downstream end of the third high-speed passages 22a, 22bc, and 22d. These passages 31 and 32 are formed in the supercharger casing 30. The supercharger casing 30 is coupled to the exhaust manifold 20 by sixth to tenth stud bolts and nuts V6 to V10 described later.

  As shown in FIGS. 3 and 7, the low-speed exhaust introduction passage 31 and the high-speed exhaust introduction passage 32 are partitioned into two upper and lower stages by partition walls 30a extending along the flow direction of the exhaust gas. The upper low-speed exhaust introduction passage 31 has a smaller exhaust gas flow area than the lower high-speed exhaust introduction passage 32.

  These exhaust introduction passages 31 and 32 are for introducing exhaust gas from the engine body side into the turbine 52 of the turbocharger 50, and from the turbine housing 52a housing the turbine 52 toward the engine body side. It extends (see FIG. 7).

  The low-speed exhaust introduction passage 31 is a common passage (collection passage) that communicates with the downstream ends of the first to third low-speed passages 21a, 21bc, and 21d. This is a common passage (collection passage) that communicates with the downstream ends of the third high-speed passages 22a, 22bc, and 22d.

  As shown in FIG. 8, the high-speed exhaust introduction passage 32 is widened in the cylinder row direction on the engine body side, and in this case, is widened in a biased manner toward the non-compressor side (left side with respect to FIG. 8). The compressor-side wall surface and the non-compressor-side wall surface of the high-speed exhaust introduction passage 32 are inclined from the engine body side toward the outlet side of the high-speed exhaust introduction passage 32 (inlet side of the turbine 52).

  As shown in FIG. 9, the low-speed exhaust introduction passage 31 is widened on the engine body side in the cylinder row direction, and in this case, it is widened by being biased toward the non-compressor side (left side with respect to FIG. 9). The compressor-side wall surface and the non-compressor-side wall surface of the low-speed exhaust introduction passage 31 are inclined from the engine body side toward the outlet side of the low-speed exhaust introduction passage 31 (inlet side of the turbine 52).

  As shown in FIGS. 2 and 7 to 9, low-speed exhaust introduction in the axial direction on the turbocharger 50 side with respect to the center (engine center) B of the cylinder row length in the cylinder row direction on the engine body side. The center (turbine center) C of the outlet of the passage 31 and the high-speed exhaust introduction passage 32 is biased toward the compressor 53 side in the axial direction.

  As shown in FIG. 3, when the exhaust variable valve 23 is closed, the exhaust gas is introduced into the turbine 52 through the first to third low speed passages 21a, 21bc, 21d and the low speed exhaust introduction passage 31. When the exhaust variable valve 23 is opened, the exhaust gas passes through the first to third low speed passages 21a, 21bc, 21d, the first to third high speed passages 22a, 22bc, 22d, the low speed exhaust introduction passage 31, and It is introduced into the turbine 52 through the high-speed exhaust introduction passage 32. That is, the first to third low-speed passages 21a, 21bc, 21d and the low-speed exhaust introduction passage 31 are passages through which exhaust gas always flows regardless of the engine rotation speed, and the first to third high-speed passages 22a, 22bc. 22d and the high-speed exhaust introduction passage 32 are passages through which exhaust gas flows only when the engine rotational speed is equal to or higher than the intercept rotational speed.

  Therefore, in the low speed range where the engine rotation speed is lower than the intercept rotation speed, the exhaust gas flow area of the first to third low speed passages 21a, 21bc, 21d and the low speed exhaust introduction passage 31 is small, and the exhaust valve 8 is opened. The flow rate of exhaust gas (blowdown gas) exhausted immediately after that in the first to third low-speed passages 21a, 21bc, 21d and the low-speed exhaust introduction passage 31 increases, and the pressure of the exhaust gas acting on the turbine 52 increases. Rises. That is, the dynamic pressure supercharging effect is strengthened.

  Further, in the low speed range where the engine rotation speed is lower than the intercept rotation speed, the first to third low speed passages 21a for the blowdown gas are equivalent to the small exhaust gas flow areas of the first to third low speed passages 21a, 21bc and 21d. , 21bc, 21d, the flow velocity is increased, and the downstream ends of the first to third low speed passages 21a, 21bc, 21d are formed into a throttle shape, so that the first to third low speed passages 21a, 21bc are provided. , 21d, the speed of the exhaust gas ejected from the downstream end of the low speed exhaust introduction passage 31 is increased, the negative pressure generated in the low speed exhaust introduction passage 31 is increased, and the scavenging of the residual gas in the cylinder 4 is promoted. Is done. That is, the ejector effect is strengthened.

  As shown in FIG. 10, the exhaust gas ejected from the downstream ends of the first to third low-speed passages 21a, 21bc, 21d passes from the engine body side to the outlet side of the low-speed exhaust introduction passage 31 (inlet side of the turbine 52). The first to third flow so as to flow along the wall on the compressor side (the right side in FIG. 10) and the wall on the side opposite to the compressor of the low-speed exhaust introduction passage 31 that is inclined toward (). The ejection angle of the exhaust gas that is ejected from the downstream ends of the low speed passages 21a, 21bc, 21d to the low speed exhaust introduction passage 31 (inclination angle of the broken line in the figure) is set.

  As shown in FIG. 10, the center of the flow of exhaust gas ejected from the downstream ends of the first to third low-speed passages 21 a, 21 bc, 21 d (broken line in the figure) is the low-speed exhaust introduction passage 31. Exhaust gas ejected from the downstream ends of the first to third low speed passages 21a, 21bc, and 21d to the low speed exhaust introduction passage 31 so as to be concentrated at the center of the outlet (inlet of the turbine 52) (see the black circle in the figure). A gas ejection angle (inclination angle indicated by a broken line in the figure) is set.

  Here, the point where the center of the flow of the exhaust gas concentrates (black circle in the figure) is provided in the narrowest part of the low-speed exhaust introduction passage 31. The exhaust gas ejection angle is set to a relatively shallow angle.

  Returning to FIG. 1, a waste passage 55 that bypasses the turbine 52 of the turbocharger 50 and a wastegate valve 56 that opens and closes the waste passage 55 are provided in the exhaust passage 33.

  Further, in order to perform exhaust gas recirculation (EGR) for returning a part of the exhaust gas flowing through the exhaust passage 33 to the intake passage 10, an EGR passage 60 that connects the exhaust passage 33 and the intake passage 10 is provided. The introduction portion of the EGR passage 60 on the exhaust passage 33 side opens downstream of the variable exhaust valve 23 in the high-speed exhaust introduction passage 32. A lead-out portion on the intake passage 10 side of the EGR passage 60 opens between the throttle valve 12 and the surge tank 13. The EGR passage 60 is provided with an EGR cooler 61 that cools the gas that passes through the EGR passage 60 and an EGR valve 62 that opens and closes the EGR passage 60. In the present embodiment, the upstream portion of the EGR passage 60 is formed inside the exhaust manifold 20 and the cylinder head 2.

  The engine body is provided with an intake side variable valve timing mechanism 15i and an exhaust side variable valve timing mechanism 15e. These variable valve timing mechanisms 15i and 15e translate the valve opening start timing and the valve closing timing of the intake valve 7 and the exhaust valve 8 while maintaining the valve opening periods of the intake valve 7 and the exhaust valve 8.

  In this embodiment, when the engine rotation speed is lower than the intercept rotation speed, that is, in the low speed range where the exhaust variable valve 23 is closed, the opening period of the intake valve 7 and the opening period of the exhaust valve 8 of each cylinder 4 are predetermined. The overlap period overlaps and the opening of the exhaust valve 8 of each cylinder 4 is started during the overlap period of the other cylinder 4 in the previous exhaust order.

  Specifically, as shown in FIG. 11, the exhaust valve 8 of the third cylinder 4c opens during the overlap period (T_O / L) between the intake valve 7 and the exhaust valve 8 of the first cylinder 4a, and the third During the overlap period (T_O / L) between the intake valve 7 and the exhaust valve 8 of the cylinder 4c, the exhaust valve 8 of the fourth cylinder 4d is opened, and the intake valve 7 and the exhaust valve 8 of the fourth cylinder 4d are over. The exhaust valve 8 of the second cylinder 4b opens during the lap period (T_O / L), and the first cylinder 4a during the overlap period (T_O / L) between the intake valve 7 and the exhaust valve 8 of the second cylinder 4b. The exhaust valve 8 is opened.

  As shown in FIG. 3, the first to third low-speed passages 21a, 21bc, 21d and the low-speed exhaust introduction passage 31 are more than the first to third high-speed passages 22a, 22bc, 22d and the high-speed exhaust introduction passage 32. Is also arranged inside the turbine 52 in the radial direction. That is, the low speed exhaust introduction passage 31 is arranged closer to the axial center of the turbocharger 50 in the radial direction than the high speed exhaust introduction passage 32.

  As shown in FIGS. 3, 4 and 6, an assembly flange 20 g to the cylinder head 2 is provided at the end of the exhaust manifold 20 on the cylinder head 2 side. The exhaust manifold 20 is assembled to the cylinder head 2 via the assembly flange 20g. Specifically, as shown in FIG. 4, first to fifth bolt insertion holes V1 to V5 are provided in the assembly flange 20g, and stud bolts attached to the cylinder head 2 are inserted into these bolt insertion holes V1 to V5. The exhaust manifold 20 is assembled to the cylinder head 2 by tightening with a nut. In the present embodiment, the symbols V1 to V5 are used for the first to fifth bolt insertion holes and also for the first to fifth stud bolts and nuts inserted through the first to fifth bolt insertion holes. It is done.

  As shown in FIGS. 3, 5, and 6, a flange 20 f to be attached to the supercharger casing 30 is provided at the end of the exhaust manifold 20 on the supercharger casing 30 side. Further, as shown in FIGS. 3 and 7 to 9, an assembly flange 30 f to the exhaust manifold 20 is provided at the end of the supercharger casing 30 on the exhaust manifold 20 side. The supercharger casing 30 is assembled to the exhaust manifold 20 via the assembly flange 30f. Specifically, as shown in FIG. 7, the assembly flange 30f is provided with sixth to tenth bolt insertion holes V6 to V10, and these bolt insertion holes V6 to V10 are attached to the assembly flange 20f of the exhaust manifold 20. The turbocharger casing 30 is assembled to the exhaust manifold 20 by inserting a stud bolt (see FIG. 5) and tightening with a nut. In the present embodiment, the symbols V6 to V10 are used for the sixth to tenth bolt insertion holes and also for the sixth to tenth stud bolts and nuts inserted through the sixth to tenth bolt insertion holes. It is done.

  Here, the assembly flange 30f is provided at the end of the exhaust introduction passages 31 and 32 on the engine main body side, and is an assembly portion for assembling the turbocharger 50 on the engine main body side. The tenth stud bolt and nuts V6 to V10 are fastening members for assembling the turbocharger 50 to the engine body side, that is, fastening members used when the turbocharger 50 is assembled to the engine body side, The sixth to tenth bolt insertion holes V6 to V10 are attached portions in which the sixth to tenth stud bolts and the nuts V6 to V10 are disposed, provided in the assembly flange 30f.

  In the present embodiment, the engine main body side of the exhaust introduction passages 31 and 32 integrally provided in the turbine housing 52a is widened so as to be biased toward the non-compressor side, and the turbine center C is in the axial direction with respect to the engine center B. Biased to the side. Therefore, as shown in FIG. 7, when the engine main body side of the exhaust introduction passages 31 and 32 is expanded to the same extent on the compressor side and the non-compressor side, it is hidden behind the compressor housing 53a (from the turbocharger 50 side). A sixth bolt insertion hole V6 (hidden when viewed from the engine main body side) is located in a space formed between the turbine housing 52a and the compressor housing 53a outside the radial direction of the center housing 54.

(2) Operation and the like As described above, in the present embodiment, the turbine housing 52a that houses the turbine wheel 52 provided in the exhaust passage 33, and the compressor housing 53a that houses the compressor wheel 53 provided in the intake passage 10 The turbocharger 50 includes a center housing 54 that houses a connecting shaft 51 that connects the turbine wheel 52 and the compressor wheel 53 so that the axial direction of the turbocharger 50 coincides with the cylinder row direction of the engine 1. In the turbocharger of a multi-cylinder engine in which is arranged, the following characteristic configuration is adopted.

  That is, it extends toward the engine body side from the turbine housing 52a, exhaust introduction passages 31, 32 for introducing exhaust gas from the engine body side to the turbine wheel 52, and ends of the exhaust introduction passages 31, 32 on the engine body side. And an assembly flange 30f for assembling the turbocharger 50 on the engine body side. The assembly flange 30f is provided with bolt insertion holes V6 to V10 in which stud bolts and nuts used when the turbocharger 50 is assembled to the engine body side are arranged. The engine main body side of the exhaust introduction passages 31 and 32 is widened in the cylinder row direction. The center C of the outlet of the exhaust introduction passages 31 and 32 in the axial direction on the turbocharger 50 side is biased toward the compressor side in the axial direction with respect to the center B of the cylinder row length in the cylinder row direction on the engine body side. ing.

  According to this configuration, as described above, the sixth bolt insertion hole V6 is positioned in the space formed between the turbine housing 52a and the compressor housing 53a outside the center housing 54 in the radial direction.

  Therefore, as shown by an arrow A in FIG. 2, the turbocharger 50 can be assembled by inserting a finger or a tool into the space from the turbocharger 50 side with respect to the sixth bolt insertion hole V6. . That is, the turbocharger 50 can be assembled to the exhaust manifold 20 using the space. As a result, a reduction in the number of fastening members such as bolts and nuts is avoided, and the support rigidity of the turbocharger 50 is ensured.

  In the present embodiment, the exhaust introduction passages 31 and 32 are a high-speed exhaust introduction passage 32 through which exhaust gas flows only when the engine rotational speed is equal to or higher than the intercept rotational speed, and a low-speed exhaust passage through which exhaust gas constantly flows regardless of the engine rotational speed. It is divided into an exhaust introduction passage 31. The low speed exhaust introduction passage 31 is disposed on the radially inner side of the turbine 52 with respect to the high speed exhaust introduction passage 32. The exhaust gas distribution area of the low-speed exhaust introduction passage 31 is set to a value smaller than the exhaust gas distribution area of the high-speed exhaust introduction passage 32. In addition, at least the engine body side of the low-speed exhaust introduction passage 31 is widened so as to be biased toward the non-compressor side.

  According to this configuration, the exhaust introduction passages 31 and 32 are divided into two for low speed and for high speed, and the low speed exhaust introduction passage 31 is disposed radially inward of the turbine 52 with respect to the high speed exhaust introduction passage 32. Therefore, the low speed exhaust introduction passage 31 is arranged closer to the axial center of the turbocharger 50 in the radial direction than the high speed exhaust introduction passage 32. Therefore, in particular, when the low-speed exhaust introduction passage 31 is widened to the same extent on the compressor side and the non-compressor side, compared to when the high-speed exhaust introduction passage 32 is widened to the same extent on the compressor side and the anti-compressor side. Thus, the possibility that the bolt insertion hole is hidden behind the compressor housing 53a increases. For example, referring to FIG. 7, the bolt insertion hole V6 closer to the shaft center is hidden behind the compressor housing 53a than the bolt insertion hole V8 (when the engine body side is viewed from the turbocharger 50 side) There is a high possibility of hiding.

  In addition, since the low-speed exhaust introduction passage 31 is widened toward the non-compressor side, a bolt insertion hole V6 that is likely to be hidden behind the compressor housing 53a is provided between the turbine housing 52a and the compressor housing 53a. It can be located in space. In this case, since the exhaust gas flow area of the low-speed exhaust introduction passage 31 is smaller than the exhaust gas flow area of the high-speed exhaust introduction passage 32, the high-speed exhaust introduction passage 32 is widened toward the non-compressor side. In comparison, the amount of deviation of the turbine center C with respect to the engine center B can be reduced. Therefore, the equal length and the equal volume of the exhaust passage 33 of each cylinder 4 are not significantly impaired, and the dynamic pressure exhaust performance such as the ejector effect is improved.

  In the present embodiment, the upstream end of the exhaust port 6 of the first cylinder 4a, the exhaust port 6 of the fourth cylinder 4d, the exhaust ports 6 of the second cylinder 4b and the third cylinder 4c, whose exhaust order is not continuous, Is connected to the first to third independent exhaust passages 16a, 16bc, 16d, and the first to third low speeds are connected to the downstream ends of the first to third independent exhaust passages 16a, 16bc, 16d. The passages 21a, 21bc, 21d and the first to third high speed passages 22a, 22bc, 22d are provided. The exhaust gas circulation areas of the first to third low speed passages 21a, 21bc, 21d are set to be smaller than the exhaust gas circulation areas of the first to third high speed passages 22a, 22bc, 22d. The downstream ends of the first to third low speed passages 21a, 21bc, and 21d are formed in a throttle shape so that the exhaust gas flow area is reduced. The low-speed exhaust introduction passage 31 is a common passage that communicates with the downstream ends of the first to third low-speed passages 21a, 21bc, and 21d, and the high-speed exhaust introduction passage 32 is used for the first to third high-speed passages. This is a common passage that communicates with the downstream ends of the passages 22a, 22bc, and 22d. In addition, when the engine rotation speed is less than the intercept rotation speed, the opening period of the intake valve 7 and the opening period of the exhaust valve 8 of each cylinder 4 overlap each other by a predetermined overlap period (T_O / L), The opening of the exhaust valve 8 of each cylinder 4 is started during the overlap period (T_O / L) of the other cylinder 4 in the previous exhaust order.

  According to this configuration, in the low speed range where the engine rotation speed is lower than the intercept rotation speed, the exhaust gas discharged from the cylinder 4 is the independent exhaust passages 16a, 16bc, 16d and the low speed passages 21a, 21bc, 21d on the engine body side. And the low-speed exhaust introduction passage 31 on the turbocharger 50 side, the exhaust gas discharged from the cylinder 4 is introduced into the engine body in a high speed region where the engine rotation speed is higher than the intercept rotation speed. Side independent exhaust passages 16a, 16bc, 16d, low speed passages 21a, 21bc, 21d and high speed passages 22a, 22bc, 22d, low speed exhaust introduction passage 31 and high speed exhaust introduction passage 32 on the turbocharger 50 side. And is introduced into the turbine 52.

  Therefore, in the low speed region, the exhaust gas flow area of the low speed passages 21a, 21bc, 21d and the low speed exhaust introduction passage 31 is small, so that the exhaust gas (blowdown gas) discharged immediately after the exhaust valve 8 is opened is slow. The flow velocity in the use passages 21a, 21bc, 21d and the low speed exhaust introduction passage 31 increases, and the pressure of the exhaust gas acting on the turbine 52 increases. That is, the dynamic pressure supercharging effect is strengthened.

  Further, in the low speed region, the flow velocity in the low speed passages 21a, 21bc, 21d of the blowdown gas is increased by the small exhaust gas flow area of the low speed passages 21a, 21bc, 21d. Since the downstream ends of 21bc and 21d are formed in a throttle shape, the speed of the exhaust gas ejected from the downstream ends of the low speed passages 21a, 21bc and 21d to the low speed exhaust introduction passage 31 is increased, and the low speed exhaust is introduced. The negative pressure generated in the passage 31 increases, and scavenging of the residual gas in the cylinder 4 is promoted. That is, the ejector effect is strengthened.

  In this case, since negative pressure acts during the overlap period (T_O / L) of the intake valve 7 and the exhaust valve 8, a blow-through flow is generated from the intake port 5 of the cylinder 4 to the exhaust port 6, and the ejector effect As a result, the amount of gas sucked out in step S5, and consequently the amount of gas acting on the turbine 52, is increased, and the turbine driving force is increased.

  As described above, the supercharging capability in the engine low speed region is improved, and the engine torque is improved.

  In the present embodiment, the compressor-side wall surface and the non-compressor-side wall surface of the low-speed exhaust introduction passage 31 are inclined from the engine body side toward the outlet side of the low-speed exhaust introduction passage 31 (inlet side of the turbine 52). . In addition, the exhaust gas ejected from the downstream ends of the first to third low-speed passages 21a, 21bc, 21d flows along the compressor-side wall surface and the non-compressor-side wall surface of the low-speed exhaust gas introduction passage 31; The center of the flow of the exhaust gas ejected from the downstream ends of the first to third low speed passages 21a, 21bc, 21d is concentrated at the center of the outlet of the low speed exhaust introduction passage 31 (the inlet of the turbine 52). The ejection angle of the exhaust gas ejected from the downstream ends of the first to third low speed passages 21a, 21bc, 21d to the low speed exhaust introduction passage 31 is set. The exhaust gas ejection angle is set to a relatively shallow angle.

  According to this configuration, since the exhaust gas flows along the compressor-side wall surface and the non-compressor-side wall surface of the low-speed exhaust introduction passage 31 (Coanda effect), the exhaust gas introduced into the turbine 52 by the low-speed exhaust introduction passage 31. The gas strikes the turbine 52 vertically. Further, since the center of the exhaust gas flow is concentrated at the center of the outlet of the low speed exhaust introduction passage 31, it is ejected from the downstream ends of the first to third low speed passages 21a, 21bc, 21d to the low speed exhaust introduction passage 31. The exhaust gas thus collided with the opposite wall surface is prevented from returning to the first to third low-speed passages 21a, 21bc, 21d (the apparent gas amount is reduced). As a result, the exhaust gas ejected from the downstream ends of the first to third low-speed passages 21a, 21bc, 21d efficiently flows through the low-speed exhaust introduction passage 31 and is introduced into the turbine 52. And the ejector effect is further enhanced. This is because the center of the exhaust gas flow is concentrated at the narrowest portion of the low-speed exhaust introduction passage 31 and the exhaust gas ejection angle is set to a relatively shallow angle. To be further enhanced.

  In the above-described embodiment, the low-speed exhaust introduction passage 31 is largely biased and widened toward the non-compressor side, and the high-speed exhaust introduction passage 32 is narrowed and widened toward the anti-compressor side. The introduction passage 32 may also be widened with a large deviation toward the non-compressor side.

  Further, the number of attached portions (bolt insertion holes) or fastening members (stud bolts and nuts) is not limited.

  Moreover, a fastening member is not restricted to a volt | bolt and a nut, Another fastening member may be sufficient.

  Further, the passage in the exhaust manifold 20 and the passage in the supercharger casing 30 are not divided into two, and the present invention can also be applied to a turbocharger of an exhaust system multi-cylinder engine of one passage.

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder head 4a-4d 1st-4th cylinder 5 Intake port 6 Exhaust port 7 Intake valve 8 Exhaust valve 9 Spark plug 10 Intake passage 11 Intercooler 12 Throttle valve 13 Surge tank 14 Intake manifold 15i, 15e Variable valve timing Mechanisms 16a, 16bc, 16d First to third independent exhaust passages 16b, 16c First and second branch passages 20 Exhaust manifold 20a Bulkhead 20f Flange 20g to turbocharger casing Assembly flanges 21a, 21bc to cylinder head , 21d First to third low-speed passages 22a, 22bc, 22d First to third high-speed passages 23 Exhaust variable valve 30 Supercharger casing 30a Partition wall 30f Assembly flange to exhaust manifold (assembly part)
31 Exhaust introduction passage for low speed 32 Exhaust introduction passage for high speed 33 Exhaust passage 50 Turbocharger 51 Connecting shaft 52 Turbine wheel 52a Turbine housing 53 Compressor wheel 53a Compressor housing 54 Center housing 55 Waist passage 56 West gate valve 60 EGR passage 61 EGR Cooler 62 EGR valve A Turbocharger assembly work direction B Center of cylinder row length in the cylinder row direction (engine center)
C Center of outlet of exhaust introduction passage in axial direction (turbine center)
V1 to V10 Mounted part (bolt insertion hole) or fastening member (stud bolt and nut)

Claims (3)

A turbine housing that houses a turbine wheel provided in an exhaust passage, a compressor housing that contains a compressor wheel provided in an intake passage, and a center housing that houses a connecting shaft that connects the turbine wheel and the compressor wheel. A turbocharger for a multi-cylinder engine in which the turbocharger is arranged so that the axial direction of the turbocharger provided is aligned with the cylinder row direction of the engine,
An exhaust introduction passage extending from the turbine housing toward the engine body, and introducing exhaust gas from the engine body to the turbine wheel;
Provided at an end of the exhaust introduction passage on the engine body side, and an assembly portion for assembling the turbocharger on the engine body side;
The assembly portion is provided with a mounting portion of a fastening member used when the turbocharger is assembled to the engine body side,
The engine body side of the exhaust introduction passage is widened in the cylinder row direction is widened biased counterclockwise compressor side, and, with respect to the center of the cylinder bank length in the cylinder row direction of the engine body, the exhaust introduction The center of the outlet, which is the opening on the turbine wheel side of the passage , is biased toward the compressor side ,
The exhaust introduction passage is divided into a high-speed exhaust introduction passage through which exhaust gas flows only when the engine rotation speed is equal to or higher than a predetermined reference rotation speed, and a low-speed exhaust introduction passage through which exhaust gas constantly flows regardless of the engine rotation speed. And
The low-speed exhaust introduction passage is disposed radially inward of the turbine from the high-speed exhaust introduction passage,
The length of the low-speed exhaust introduction passage in the cylinder row direction is such that the exhaust gas flow area of the low-speed exhaust introduction passage is smaller than the exhaust gas flow area of the high-speed exhaust introduction passage. Is set shorter than the length of the high-speed exhaust introduction passage in the direction,
A turbocharger for a multi-cylinder engine, characterized in that at least the engine main body side of the low-speed exhaust introduction passage is widened toward the non-compressor side . The turbocharger for a multi-cylinder engine according to claim 1 ,
On the engine body side, a plurality of independent exhaust passages having upstream ends connected to exhaust ports of one cylinder or a plurality of cylinders whose exhaust order is not continuous, and an upstream end portion at a downstream end portion of the plurality of independent exhaust passages A plurality of low-speed passages and a plurality of high-speed passages connected to each other;
The exhaust gas flow area of the plurality of low speed passages is set to a value smaller than the exhaust gas flow area of the plurality of high speed passages,
The downstream ends of the plurality of low-speed passages are formed in a throttle shape so that the exhaust gas flow area is reduced,
The low-speed exhaust introduction passage is a common passage that communicates with the downstream ends of the plurality of low-speed passages, and the high-speed exhaust introduction passage communicates with the downstream ends of the plurality of high-speed passages, respectively. A common passage, and
When the engine rotation speed is lower than the reference rotation speed, the intake valve opening period and the exhaust valve opening period of each cylinder overlap with each other by a predetermined overlap period, and the exhaust order of the other cylinders one before is exhausted. A turbocharger for a multi-cylinder engine, wherein an opening of an exhaust valve of each cylinder is started during an overlap period. The turbocharger for a multi-cylinder engine according to claim 2 ,
The compressor-side wall surface and the non-compressor-side wall surface of the low-speed exhaust introduction passage are inclined from the engine body side toward the outlet side,
Exhaust gas ejected from the downstream ends of the plurality of low-speed passages flows along the compressor-side wall surface and the non-compressor-side wall surface, and exhaust gas ejected from the downstream end portions of the plurality of low-speed passages A multi-cylinder characterized in that an ejection angle of exhaust gas ejected from downstream ends of the plurality of low-speed passages is set so that the center of the flow is concentrated at the center of the outlet of the low-speed exhaust introduction passage. Engine turbocharger.

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