JPH02271025A - Exhaust structure of multicylinder engine - Google Patents

Abstract

PURPOSE:To suppress the thermal damage by an exhaust pipe by extending exhaust passages, which communicate with the cylinders of banks on both sides, on the opposite side to the middle bank, and exhaust passages, which communicates the the cylinders of the middle bank, on both sides of the middle bank putting them in two. CONSTITUTION:In an engine 1 equipped with a central bank 2, a righthand bank 2, and a lefthand bank 4, exhaust ports 17..., which communicate with the cylinders of the banks 3 and 4 on both sides, are extended outside the banks 3 and 4, in a word, on the opposite side to the central bank 2. On the other hand, exhaust ports 17..., which communicate with the cylinders of the central bank 2, are extended on both sides of the central bank 2 putting them in two. Hereby, between adjacent banks 2-4, the effect by the exhaust heat from the cylinders of the banks 3 and 4 on both sides can be removed. Moreover, since the exhaust passages of the cylinders of the central bank 2 are put in two on both sides, the heat load is dispersed and the heat effect can be suppressed low. Accordingly, the heat damage by exhaust can be prevented effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the structure of an exhaust system in a multi-cylinder engine, particularly an engine having three or more banks.

(Prior Art) Today, in order to improve the quality of automobile engines, the number of cylinders is increased to increase the number of cylinders. However, when the number of cylinders increases in this way, in an in-line engine in which a plurality of cylinders are arranged in series, the length in the crankshaft direction increases, making it difficult to reduce the overall size of the engine. On the other hand, with a so-called V-type engine in which half of the cylinders are arranged in a V-shaped bank, the overall length of the engine can be shortened compared to an in-line engine, but as the number of cylinders increases further, the overall length of the engine becomes shorter. There are limits to this.

Therefore, conventionally, as an engine adopted when the number of cylinders increases in this way, for example, U.S. Patent Section 2.722.9
As disclosed in No. 23, an engine called a W-type engine is known in which the number of banks is three and cylinders are distributed in each bank.

(Problems to be Solved by the Invention) In this conventional engine, an intake pipe and an exhaust pipe communicating with the cylinders of each bank are arranged in the space between adjacent banks. Since this exhaust pipe is disposed between banks, there is a problem in that heat damage caused by exhaust heat from the exhaust pipe is significant. In other words, since the exhaust pipes of the cylinders in the center bank are adjacent to the exhaust pipes of the cylinders in both banks, the heat load is concentrated on the exhaust system, and a large heat load is placed on the cylinder block, surge tank, etc. It becomes difficult to cool the exhaust pipe itself, which adversely affects the reliability of the exhaust pipe.

In addition, because the exhaust pipes of the cylinders in the center bank are adjacent to the intake pipes of the cylinders in both banks, the temperature of the intake air in the intake manifold that is in contact with the exhaust pipes increases, and the volumetric efficiency of intake air decreases. Or the fuel system may be adversely affected.

The present invention has been made in view of the above, and its main purpose is to improve the arrangement of the exhaust system in a multi-cylinder engine with three or more banks as described above. The purpose is to suppress heat damage caused by the pipes as much as possible, improve reliability of the exhaust pipe and fuel system, and improve the volumetric efficiency of intake air.

(Means for Solving the Problem) In order to achieve the above object, in the invention according to claim (1), in a multi-cylinder engine having three or more banks extending in the crankshaft direction, the cylinders of the banks on both sides are A communicating exhaust passage is provided extending to the outside of the bank, that is, to the side opposite to the intermediate bank. On the other hand, the exhaust passages communicating with the cylinders of the intermediate bank are distributed and extended on both sides of the intermediate bank.

Further, in order to suppress exhaust interference between cylinders due to exhaust pulsation, in the invention according to claim (2), the exhaust passages of cylinders in which the ignition order is not consecutive in each bank are grouped together.

Furthermore, in order to effectively suppress the rise in intake air temperature due to exhaust heat, in the invention according to claim (3), the exhaust passage communicating with the cylinders of the middle bank is arranged in a direction opposite to the intake passage with respect to the center of the bank. It will be extended to

(Function) With the above configuration, in the invention according to claim (1), among the plurality of banks of the engine, the exhaust passages of the cylinders of both banks extend to the outside of the banks, so that between the adjacent banks The influence of exhaust heat from the cylinders in both banks can be eliminated.

Moreover, since the exhaust passages of the cylinders in the intermediate bank are distributed to both sides of the intermediate bank, the heat load is distributed and the thermal influence can be kept low, thereby effectively preventing heat damage caused by exhaust gas. I can do it.

Further, in the invention according to claim (2), since the exhaust passages of the cylinders in each bank whose ignition order is not consecutive are grouped together, exhaust interference between the cylinders can be suppressed to a low level.

Furthermore, in the invention according to claim (3), since the exhaust passage communicating with the cylinders of the intermediate bank extends in the opposite direction to the intake passage with respect to the center of the bank, the intake passage and the intake passage communicate with each cylinder of the same bank. The exhaust passage is separated from the exhaust passage, and the intake air is no longer heated by the exhaust heat, so that an increase in the intake air temperature due to the exhaust heat can be effectively suppressed.

(Example) Embodiments of the present invention will be described below based on the drawings.

In FIGS. 1 to 3, 1 indicates W according to an embodiment of the present invention.
This engine 1 is a type 12-cylinder engine, and the engine 1 has three cylinders extending in the front-rear direction (crankshaft direction), right and left, and in the center.
It has two banks 2 to 4.

Further, as shown in FIG. 3, this engine 1 includes a cylinder block 5 and each bank 2 to 4 of the cylinder block 5.
The basic component includes three cylinder heads 6 to 8 joined to the upper surface of the cylinder block 5, and four crank bins 9a, 9a, . . . are provided at the lower end of the cylinder block 5.
A crankshaft 9 with (only one shown) is rotatably supported. The central bank 2 constitutes an intermediate bank according to the present invention, and this bank 2 extends along a vertical plane, and a bank 4 on the left with respect to the central bank 2.
is inclined at 60 degrees to the left (right side in FIG. 3), and the right bank 3 is inclined at 60 degrees to the right (to the left in FIG. 3). The central bank 2 has first cylinders 10 in order from the front side (left side in Figure 2).
a, 4th cylinder 10d1 7th cylinder 10g and 10th cylinder 1
Four cylinders of 0j are formed. Similarly, in the right bank 3, the second cylinder 10b1, the fifth cylinder 10e1, the eighth cylinder
Four cylinders are formed in the left bank 4: a third cylinder 10C, a sixth cylinder 10f, a ninth cylinder 10i, and a twelfth cylinder 10g. A piston 11 is fitted in each cylinder 10a to 1011 so as to be able to reciprocate, and this piston 11 is connected to the crankshaft 9 via a connecting rod 12.
is connected to.

In that case, the first cylinder 1 located at the front end of each bank 2 to 4
The cylinders 0a to 3rd 10c are grouped together, and the pistons 11, 11 . Connecting rod 12 connected to...
,12. ... are sequentially connected in series to the crank bin 9a at the front end of the crankshaft 9. Although not shown, similarly, the pistons 11 in the fourth cylinder 10d to the sixth cylinder 10f located second from the front of each bank 2 to 4,
11. ... is the second crank pin 9a from the front of the crankshaft 9, and the pistons 11, 11, . ... is 3 from the front of crankshaft 9
The pistons 11, 11 . ... are respectively connected to the fourth (rear end) crank bin 9a from the front of the crankshaft 9. And such pistons 11, 11 .
... and the crankshaft 9, the central bank 2 is relatively offset to the front than the right bank 3, and the right bank 3 is relatively offset to the front than the left bank 4. are doing.

Ignition order (intake order) of the above 12 cylinders 10a to 1ON
are 1st cylinder 10a1 12th cylinder 10g1 5th cylinder 10e
1 7th cylinder 10g 1 6th cylinder 10f 1 2nd cylinder 10b1
10th cylinder 10j, 3rd cylinder 10C1, 8th cylinder 10h1
They are set in the following order: 4th cylinder 10d1, 9th cylinder 1011, and 11th cylinder 10. The ignition order of the cylinders 10a to ION is summarized for banks 2 to 4 as shown in the table below.

Each of the cylinder heads 6 to 8 has cylinders 10a to 10f.
A plug hole 14, 1.4°, for attaching a spark plug 13 for igniting the intake air in the internal combustion chamber is opened at a position approximately on the center line of the cylinder. Each cylinder head 6 to 8 is also provided with an intake boat 15.1 that forms a part of the intake passage and whose downstream end faces the combustion chamber in each of the cylinders 10a to 10Ω.
5. ..., and an exhaust bow that forms part of the exhaust passage and whose upstream end faces the combustion chamber in each cylinder 10a to 10ρ)17.
17. . . . is formed through it. Then, cylinders 10c, 10f, 10i, 1 (01
Intake boat 15, 15. ...is cylinder head 8
Exhaust port 17, 17. . . . are opened on the left side surface, that is, on the outside of the engine 1. On the other hand, the intake boats 15, 15 . ... is the left side of the cylinder head 7 (
Exhaust boats 17, 17 .
. . . are opened on the right side, that is, on the outside of the engine 1. In addition, as shown in Fig. 4, the center bank 2
Among the cylinders 10a, 10d, 10g, and 10j, the first cylinder 10a and the first cylinder located at the front and rear ends of bank 2
The intake boat 15.15 of the 0 cylinder 10j is on the left side of the cylinder head 6 (the surface facing the left bank 4), and the exhaust boat 17.17 is on the right side of the cylinder head 6 (the surface facing the right bank 3).
The fourth opening is located between the front and back, while the fourth opening is located between the front and back.
Intake boat for cylinder 10d and 7th cylinder 10g 15.15
is opened on the right side of the cylinder head 6 (the surface facing the right bank 3), and the exhaust boat 17, 17 is opened on the left side of the same (the surface facing the left bank 4). That is,
The four cylinders 10a of the central bank 2, 1. Od, 10g,
The exhaust passage and the intake passage communicating with the bank 10j extend in opposite directions from the center of the bank 2. 16 is an intake valve that opens and closes the downstream end of the intake boat 15, and 18 is an exhaust valve that opens and closes the upstream end of the exhaust port 17.

In the space between the center bank 2 and the right bank 3, three right sub-surge tanks 19 to 21, which extend parallel to each other in the crankshaft direction, are arranged side by side in the left-right direction. As shown in FIGS. 5 and 7, these surge tanks 19 to 21 are formed by partitioning the inside of one hollow container extending in the direction of the crankshaft with two partition walls 25 and 26. is occluded. And these subsurge tanks 19-21
Of these, the surge tank 19 at the left and right center has two intake manifolds 27, 27 communicating with the intake boats 1, 5, 15 of the second cylinder 10b and the eleventh cylinder 10 in the right bank 3, and the left end surge tank 19. The surge tank 21 has two intake manifolds 27.27 communicating with each intake boat 15.15 of the fifth cylinder 10e and the eighth cylinder 10h in the same bank 4, and the rightmost surge tank 20 has two intake manifolds 27. 4th cylinder in 2 1. Od and 7th
Two intake manifolds 27.27 are connected to each intake boat 15.15 of the cylinder 10g.

On the other hand, three left sub-surge tanks 22 to 24 having the same structure as the right surge tanks 19 to 21 are arranged between the center bank 2 and the left bank 4. That is, as shown in FIG. 6, the front ends of the left side surge tanks 22 to 24 are closed, and the surge tank 22 in the center of the left and right is filled with the intake boats 15 of the third cylinder 10c and the twelfth cylinder 1011 in the left bank 4. There are two intake manifolds 27.27 connected to the same bank 4, and two intake manifolds 27.27 connected to the surge tank 23 on the right side are connected to each intake boat 1.5.15 of the sixth cylinder 10f and the ninth cylinder 10t in the same bank 4. The intake manifold 27, 27 is located at the left end of the surge tank 24, and the first cylinder 10a in the center bank 2 is located at the left end of the surge tank 24.
Two intake manifolds 27 and 27 are connected to each intake boat 15 and 15 of the tenth cylinder 10j, respectively.

On the rear side of each of the cylinder heads 6 to 8, that is, on the opposite side to the direction of displacement of the central bank 2 with respect to the left and right banks 3 and 4, each of the subsurge tanks 19 to 24 and an intake manifold 27 connected thereto, 27. . . . A main surge tank 29 is disposed as an intake air collecting section for distributing intake air to. This surge tank 29 consists of an arc-shaped hollow container extending substantially left and right along the arrangement direction of the cylinder heads 6 to 8, and has an opening (not shown) formed in the left and right center portions of the rear surface. The opening is connected to an air cleaner 32 via a throttle body 31 having two throttle valves 30, 30 inside.

The main surge tank 29 is independently connected to each of the sub-surge tanks 19-24. This main surge tank 29 and each sub surge tank 1
A variable intake mechanism 33 is disposed between the two and the intake passage 9-24 to change the cross-sectional area of the intake passage between the two into two levels, large and small. As shown in FIGS. 5 and 7, this variable intake mechanism 33 includes a main surge tank 29 and sub-surge tanks 19 to 2.
Primary and secondary intake passages 34°35 communicating with 4 in parallel
The primary intake passage 34 is located below the secondary intake passage 35, and its cross-sectional area is smaller than that of the secondary intake passage 35. A shatter valve 36 consisting of a butterfly valve that opens and closes the intake passage 35 is disposed in the secondary intake passage 35, and the intake stroke occurs near the intake boat 15 with the start of the intake stroke of each cylinder 10a to 10J2. The negative pressure wave of the intake air is propagated upstream and reversed to a positive pressure wave in the main surge tank 29, and the positive pressure wave is applied to the end of the intake stroke of the original cylinders 10a to 10g, thereby supercharging the intake air. At the same time, by opening and closing the shatter valve 36 according to the engine rotation speed, the cross-sectional area of the intake passage is changed to change the synchronized rotation speed of the intake dynamic supercharging in two stages,
In the low rotation range of the engine 1, the shatter valve 36 is closed and the main surge tank 29 and the sub-surge tanks 19 to 24 are communicated only through the primary intake passage 33, thereby reducing the cross-sectional area of the intake passage and allowing the synchronized rotation speed to decrease. is lowered, while in the high rotation range, the shutter valve 36 is opened and both surge tanks 29 are
．． 19 to 24 are communicated not only with the primary intake passage 34 but also with the secondary intake passage 35, thereby increasing the cross-sectional area of the intake passage and increasing the tuned rotation speed.

In each of the banks 2 to 4, the exhaust passages of the cylinders having non-consecutive ignition timings are grouped together.

That is, the intake boats 17 of each of the cylinders 10a to 10g are
An exhaust manifold 28 forming a part of an exhaust passage is connected to each of the exhaust manifolds 28 . As shown in FIG. 8, the third cylinder 10c and the twelfth cylinder 1 of the left bank 4 are
The downstream ends of the exhaust manifolds 28, 28 respectively connected to the exhaust boats 17, 17 of 0j7 are gathered together. Similarly, the sixth cylinder 10f and the ninth cylinder 10
The downstream ends of the exhaust manifold 28 and 28 that communicate with i, the second cylinder 10b and the eleventh cylinder 10k of the right bank 3
The downstream ends of the exhaust manifold 28 and 28 that communicate with each other,
The downstream ends of the exhaust manifolds 28 and 28 communicating with the fifth cylinder 10e and the eighth cylinder 10h are gathered together. With the above structure, the exhaust passages of the cylinders of the left and right banks 3, 4 extend outside the banks 3.4.

Further, an exhaust manifold 28 connected to the exhaust boat 17 of the first cylinder 10a at the front end of the central bank 2 is connected to the intake manifolds 27, 27, . It extends rearward below the main surge tank 29, and its rear end is located below the main surge tank 29. On the other hand, the first cylinder 1 is located at the rear end of the central bank 2.
The exhaust manifold 28 connected to the exhaust boat 17 of the 10th cylinder 10j whose ignition timing is not continuous with 0a is the upper 2
They are assembled in the middle of an exhaust manifold 28 that communicates with the exhaust boat 17 of the first cylinder 10a.

In addition, the fourth cylinder 10 is located between the front and rear of the central bank 2.
Exhaust manifold 28 connected to exhaust boat 17 of d
extends rearward below the intake manifolds 27, 27, . Further, the exhaust manifold 28 connected to the exhaust boat 17 of the seventh cylinder 10g on the rear side of the fourth cylinder 10d is assembled in the middle of the exhaust manifold 28 communicating with the exhaust boat 17 of the fourth cylinder 10d. With the above structure, the exhaust passages of the cylinders in the left and right banks 3 and 4 are extended to the side opposite to the center bank 2 (on the outside of the bank), and on the other hand, the four cylinders 10a of the center bank 2, The exhaust passages communicating with 10°d, 10g, and 10j are the first cylinder 10a, the tenth cylinder 10j, and the fourth cylinder 1.
．． Od and the seventh cylinder 10g are distributed and extended to both left and right sides of the central bank 2.

Therefore, in the embodiment described above, during operation of the engine 1, the intake air is supercharged by the dynamic effect of the pulsation of the intake air taken into each cylinder 10a to 10fl. That is, the negative pressure wave of intake air generated near the intake boat 15 with the start of the intake stroke of each cylinder 10a to ION propagates upstream through the intake passages in the sub-surge tanks 19 to 24 and is generated in the main surge tank 29. The positive pressure wave is reversed to a positive pressure wave, returns to the downstream side, and acts on the original cylinders 10a to ION at the end of the intake stroke just before the intake valve 16 closes, thereby supercharging the intake air. Each shatter valve 36 in the variable intake mechanism 33 is opened and closed according to the engine speed, and in the low speed range of the engine 1, the shatter valve 36 is closed and the main surge tank 29 and sub-surge tanks 19 to 24 are They are communicated only through the intake passage 34. As a result, the cross-sectional area of the intake passage becomes small, and the synchronized rotational speed of the dynamic supercharging of the intake air is set low. Therefore, as shown by the solid line in FIG. 9, the cylinders 10a to 10 are
The volumetric efficiency ηV of intake air with respect to g increases, and the output torque in the low rotation range can be increased. On the other hand, in the high rotation range of the engine 1, the shatter valve 36 opens and both surge tanks 29.
It also communicates with the next intake passage 35. This increases the cross-sectional area of the intake passage and increases the synchronized rotational speed of dynamic supercharging. Therefore, as shown by the broken line in FIG. 9, the volumetric efficiency ηV of intake air in the high speed range of the engine 1 increases, making it possible to increase the output torque. As a result, by opening and closing the shatter valve 36, the output torque of the engine 1 can be increased from a low speed range to a high speed range.

In that case, in each bank 2 to 4, cylinders whose intake strokes (ignition order) are not adjacent to each other (for example, in the center bank 2, the first cylinder 10a and the tenth cylinder 10j, or the fourth cylinder 10d and the seventh cylinder 10g ) are collected in the same sub-surge tanks 19 to 24, so the dynamic supercharging effect of the intake air can be obtained with a compact structure.

Furthermore, in this embodiment, the main surge tank 29 that constitutes a part of the intake passage is arranged at the rear side of the engine 1, so when the surge tank 29 is arranged above the banks 2 to 4, In comparison, the height of the intake system can be lowered by the amount of the main surge tank 29, and therefore the height of the entire engine 1 including the intake system can be kept low.

Furthermore, the central bank 2 is offset toward the front side relative to the left and right banks 3.degree. 4, and due to this offset, the rear portion of the central bank 2 becomes a dead space. Since the main surge tank 29 is arranged in this dead space, the total length of the engine 1 including the main surge tank 29 in the crankshaft direction can be shortened.

Further, since the variable intake mechanism 33 is disposed between the sub-surge tanks 19 to 24 and the main surge tank 29, the arrangement of the variable intake mechanism 33 becomes easy.

Furthermore, exhaust manifolds 28, 28 . ... is extended to the outside of banks 3 and 4 on both the left and right sides, so each bank 2
- 4, only the exhaust manifolds 28, 28, . can. Moreover, the exhaust manifolds 28, 28, . . . that communicate with the cylinders of the central bank 2,
For the first cylinders 1, 0a and the tenth cylinder 10j, the fourth cylinder 10d and the seventh cylinder 10j are located on the right side of the center bank 2.
Since exhaust manifolds 28, 28 .g are distributed to the same left side, Heat damage can be further effectively reduced by dispersing...

Also, the exhaust manifolds 26, 26 . . . extend to the left and right outer sides of the banks 3 and 4, so that the thermal influence of the exhaust gas from the cylinders of the banks 3 and 4 on both sides can be eliminated between the adjacent banks 2 to 4. Moreover, since the exhaust manifolds 26, 26, . Heat damage caused by exhaust gas can be effectively prevented.

Further, in each bank 2 to 4, the exhaust manifolds 26, 26 of cylinders whose ignition order is not consecutive are grouped together, so that exhaust interference due to exhaust pulsation between the cylinders can be suppressed to a low level.

Further, an exhaust manifold 26. which communicates with the cylinders of the central bank 2. 26. ... is the intake manifold 25 for bank 2. 25. ..., so the intake manifold 25 for each cylinder of the same bank 2
Since the exhaust manifold 26 and the exhaust manifold 26 are separated from each other, the intake air is no longer heated by the exhaust heat, and therefore an increase in the intake air temperature due to the exhaust heat can be suppressed more effectively.

Note that the above embodiment is a W-type 1 having three banks 2 to 4.
This is a case where the present invention is applied to a two-cylinder engine 1.
Of course, W can also be applied to engines having cylinders other than 12, and multi-cylinder engines having four or more banks.

(Effects of the Invention) As described above, according to the invention according to claim (1), in an engine having three or more banks, the exhaust passage communicating with the cylinders of the banks on both sides is provided extending outside the banks, while
The exhaust passages that communicate with the cylinders in the middle bank are distributed and extended on both sides of the middle bank, so that between adjacent banks there is no heat effect due to the exhaust gas from the cylinders in both banks, and the exhaust passages that communicate with the cylinders in the middle bank are It is possible to disperse the heat load due to exhaust gas and suppress its thermal influence, thereby effectively preventing heat damage caused by exhaust gas, improving the reliability of the exhaust manifold and fuel system, and improving the volumetric efficiency of intake air. can.

Further, according to the invention according to claim (a), by consolidating the exhaust passages of the cylinders in which the ignition order is not consecutive in each bank, exhaust interference due to exhaust pulsation between the cylinders can be suppressed to a low level.

Furthermore, according to the invention according to claim (3), by extending the exhaust passage communicating with the cylinders of the intermediate bank in a direction opposite to the intake passage with respect to the center of the bank, the intake passage for each cylinder of the intermediate bank is provided. By separating the intake air and the exhaust passage, heating of the intake air due to exhaust heat can be eliminated, and therefore, an increase in intake air temperature due to exhaust heat can be effectively suppressed.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a plan view schematically showing the overall configuration of the engine intake system, FIG. 2 is a developed view of the engine bank and intake system viewed from above, and FIG. 3 is a sectional view taken along the ■-■ line in Fig. 2, Fig. 4 is a cross-sectional view of the cylinder head in the center bank, Fig. 5 is a cross-sectional view of the right sub-surge tank, and Fig. 6 is a cross-sectional view of the left sub-surge tank. Figure 7 is a cross-sectional view taken along the line ■-■ in Figure 5, Figure 8 is a cross-sectional view of the cylinder head of the left bank, and Figure 9 is a characteristic showing changes in the volumetric efficiency of intake air due to opening and closing of the shatter valve. It is a diagram. 1... Engine 2... Center bank (intermediate bank) 3... Right bank 4... Left bank 9... Crankshaft 10a to 10J2... Cylinder 15... Intake boat 17... Exhaust boats 19 to 24...Subsurge tank 27...Intake manifold 28...Exhaust manifold 29...Main surge tank 33...Variable intake mechanism 36...Shatta Patent attorney front 1 ) Hiroshi (゛ and 2 other people)
“-(N

Claims (3)

[Claims] (1) In a multi-cylinder engine that has three or more banks extending in the direction of the crankshaft, the exhaust passages that communicate with the cylinders of the banks on both sides extend to the side opposite to the middle bank, while communicating with the cylinders of the middle bank. An exhaust structure for a multi-cylinder engine, characterized in that exhaust passages are distributed and extend on both sides of the intermediate bank. (2) A claim characterized in that the exhaust passages of cylinders in each bank whose firing order is not consecutive are grouped together
1) Exhaust structure of the multi-cylinder engine described. (3) The exhaust structure for a multi-cylinder engine according to claim 1, wherein the exhaust passage communicating with the cylinders of the intermediate bank extends in a direction opposite to the intake passage with respect to the intermediate bank.