JPH0874598A - Intake-exhaust structure of overhead valve v-type multicylinder internal combustion engine - Google Patents

Abstract

PURPOSE: To conduct a flow of high temperature exhaust into an exhaust emission control device in shortening the length of an exhaust pipe as short as possible as well as to set up an intake pipe without interfering with the exhaust pipe, in this overhead-valve V-type multicylinder internal combustion engine where an intake- exhaust valve is installed in a cylinder head and two banks of cylinder groups are arranged in V-shaped form. CONSTITUTION: An intake chamber 21 is connected to an inlet end of an intake port 16 in each cylinder bank via an intake pipe 20, and exhaust ports 17 in respective cylinder banks are joined together with each other and converged on one piece at each cylinder bank, and an exhaust branch pipe 23 is connected to each exhaust end to the exhaust ports 17, whereby this exhaust branch pipe 23 is accorded with another exhaust branch pipe 23 in the cylinder bank at the opposite side and converged into one exhaust pipe 22, and thereby the circumference of the exhaust pipe 22 and the exhaust branch pipe 23 are surrounded by an insulating pipe 24. Then, the exhaust pipe 22 is connected to an exhaust emission control device 25 installed on a transmission 2, and in this connection, a three-way catalyst is built in this exhaust emission control device 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overhead valve type V multi-cylinder internal combustion engine in which intake and exhaust valves are provided in a cylinder head and two groups of cylinders are arranged in a V shape, and the exhaust pipe length is shortened as much as possible. The present invention relates to an intake / exhaust structure for an overhead valve type V multi-cylinder internal combustion engine in which hot exhaust gas is guided to an exhaust gas purification device and an intake pipe can be arranged without interfering with the exhaust pipe.

[0002]

2. Description of the Related Art In a conventional overhead valve type V multi-cylinder internal combustion engine, an intake valve is arranged near a V bank in which two rows of cylinder groups are arranged in a V shape, and An intake pipe and an intake chamber connected to the valve are arranged in the V bank, an exhaust pipe is arranged outside the V bank, and the exhaust purification device connected to the exhaust valve via the exhaust pipe is the exhaust gas purification device. It was located on both sides of the internal combustion engine.

In such an overhead valve V-type multi-cylinder internal combustion engine, at least two exhaust gas purification devices are required, resulting in an increase in weight and cost, and an increase in the size of the internal combustion engine in the direction perpendicular to the crankshaft. I could not avoid doing it.

In the overhead valve V-type multi-cylinder internal combustion engine described in Japanese Patent Publication No. 52-7093, an exhaust gas purification device is arranged in a V bank, and an exhaust port is connected to the exhaust gas purification device. An intake pipe connected to the port is arranged above the exhaust gas purification device, and a carburetor is arranged above the intake pipe.

In the internal combustion engine described in Japanese Examined Patent Publication No. 52-7093, since the exhaust gas purifying device, the intake pipe and the carburetor are stacked above each other in a laminated form, the height of the internal combustion engine inevitably increases. When it is installed in the vehicle, the bonnet becomes high accordingly.

Since the exhaust gas purification device located further below is heated to a remarkably high temperature, even if the exhaust gas purification device has a heat insulating structure, a part of the air heated by the exhaust gas purification device touches the intake system and the intake air is taken in. May be heated and the filling efficiency may decrease.

[0007]

The present invention relates to an improvement of an overhead valve V-type multi-cylinder internal combustion engine which overcomes the above problems, and two cylinder groups are arranged in a V shape. In an overhead valve V-type multi-cylinder internal combustion engine in which a transmission is integrally provided at one shaft end of a crankshaft of the internal combustion engine, exhaust pipes connected to exhaust ports of the respective cylinders and collected are An exhaust gas purification device, which is arranged in a V bank sandwiched between two rows of V-shaped cylinder groups and has a heat insulating structure against the outside air, and is connected to the exhaust end of the exhaust pipe, is provided on the transmission. The intake pipes connected to the intake ports of the respective cylinders and collected are arranged at a position higher than the exhaust pipes in the V bank.

Since the present invention is configured as described above, the exhaust gas discharged from the exhaust port of each cylinder immediately flows into the exhaust gas purification device without being cooled by the exhaust pipe, and the exhaust gas purification device Purified by the device and released into the atmosphere.

Further, since the intake pipe does not exist above the exhaust gas purification device which is heated to a high temperature during the purification reaction, and the intake pipe is located above the exhaust pipe constructed in the heat insulating structure,
The intake air flowing through the intake pipe is hardly heated, and the decrease in filling efficiency due to heating is prevented in advance.

Particularly, in the fuel injection type internal combustion engine in which the latent heat of vaporization of the fuel is not taken away in the intake pipe, the decrease in the charging efficiency can be prevented more reliably.

Further, according to the present invention, only the exhaust pipe is arranged in the V bank, and the exhaust purification device connected thereto is arranged so as to be displaced in the crankshaft direction from the internal combustion engine. Even if the intake pipe is installed in
Since the height of the entire internal combustion engine does not significantly increase and there is no exhaust gas purification device on the side of the internal combustion engine, the internal combustion engine width dimension at right angles to the crankshaft is shortened, and as a result,
The internal combustion engine can be downsized.

Furthermore, in the present invention, since only one exhaust gas purification device is required, it is possible to reduce the cost.

By configuring the present invention as set forth in claim 2, it is sufficient to dispose one rocker shaft for each cylinder row, which simplifies the structure of the valve train and achieves cost reduction. In addition, the exhaust pipe can be integrated as a whole to reduce the surface area of the exhaust pipe to reduce the heat radiation of the exhaust gas as much as possible and maintain the exhaust gas purification performance at a high level.

Further, by constructing the present invention as set forth in claim 3, the intake and exhaust resistance can be reduced and the intake and exhaust of the engine can be smoothly performed, and the intake and exhaust can be performed according to the operating condition of the engine. The operating performance of the engine can be improved by stopping the exhaust valve or adjusting the opening / closing timing.

Further, by constructing the present invention as set forth in claim 4, it is possible to simplify the processing of the holes for mounting the fuel injection valve and the ignition plug, and at the same time, to provide the fuel injection valve and the ignition. The work of attaching and detaching the plug can be easily performed without being disturbed by the intake system and the exhaust system.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention shown in FIGS. 1 to 6 will be described below.

The overhead valve type V-4 internal combustion engine 1 is mounted on a passenger car (not shown) with the crankshaft 10 oriented in the vehicle width direction, and one end of the crankshaft 10 of the overhead valve V4 internal combustion engine 1 is mounted. The transmission 2 having a built-in clutch (not shown) is integrally provided on the side thereof, and the overhead valve V-type 4-cylinder internal combustion engine 1 is provided with two detachable cylinders on each of two rows of cylinders 8 of a cylinder block 3. Cylinder head 4 is joined, a head cover 5 is detachably attached to the cylinder head 4, a crankcase 6 is detachably attached to the bottom of the cylinder block 3, and the crankcase 6
An oil pan 7 is detachably attached to the lower part of the.

Further, the cylinder block 3 has 2 on one side.
A plurality of cylinders 8 are arranged, the two rows of cylinders 8 are arranged in a V shape at an angle of 90 ° to each other, and a piston 9 is slidably fitted in the cylinder 8.

Further, a crankshaft 10 is arranged at a position where the center lines of the cylinders 8 intersect, and the crankshaft 10 is rotatably sandwiched between a cylinder block 3 and a crankshaft holder 13 via a journal bearing 12 so as to pivot. The crankpin 11 of the crankshaft 10 and the piston 9 are supported by the connecting rod.
The crankshaft 10 is connected by 14, and the crankshaft 10 is driven to rotate counterclockwise in FIG. 1 as the piston 9 moves up and down.

Furthermore, the two cylinder heads 4 are
An intake port 16 and an exhaust port 17 are arranged near the V bank 15 between the two rows of cylinders 8 from the center line of the cylinders 8 (see FIG. 5) and are adjacent to each other in one row of cylinders 8. The exhaust openings 19 of the exhaust ports 17 corresponding to the cylinders 8 approach each other, and the intake openings 18 of the intake ports 16 are located outside the exhaust gas column of the cylinder row, and these intake openings 18 and exhaust openings 19 are It is arranged so as to be parallel to the cylinder row.

Moreover, as shown in FIGS. 4 and 5, the intake end of the intake port 16 in each cylinder row is connected to the intake chamber 21 via the intake pipe 20, and the exhaust port 17 in each cylinder row is mutually connected. Is connected to each cylinder row to form one tube, and an exhaust branch pipe 23 is connected to the exhaust end of the exhaust port 17, and the exhaust branch pipe 23 is combined with the exhaust branch pipe 23 of the opposite cylinder row. Are converged into a single exhaust pipe 22, and the outer circumferences of the exhaust pipe 22 and the exhaust branch pipe 23 are insulated pipes 24.
And the exhaust pipe 22 is connected to an exhaust gas purifying device 25 installed on the transmission 2.
The three-way catalyst (not shown) is built in the unit 25.

An intake pipe 26 communicating with an air cleaner (not shown) is connected above the intake chamber 21, and a throttle valve device 27 for adjusting the intake air amount is attached to the intake pipe 26.

Further, the intake openings 18 and the exhaust openings 19 are provided.
Are provided with an intake valve 28 and an exhaust valve 29, respectively, and a valve operating device near the V bank 15 from the intake valve 28 and the exhaust valve 29.
30 are provided.

In the valve train 30, as shown in FIGS. 1, 3 and 6, in the V bank 15, the crankshaft 10
Located directly above and parallel to the crankshaft 10, the camshaft
A sprocket 31 is rotatably supported, and a drive sprocket 32 formed at one end of the crankshaft 10 and a driven sprocket 33 integrally attached to one end of the camshaft 31 are attached to a cam chain 34.
, A chain tensioner 35 for removing looseness of the cam chain 34 is provided, and the number of teeth of the driven sprocket 33 is set to be twice the number of teeth of the drive sprocket 32.
When the crankshaft 10 rotates, the camshaft 31 is driven to rotate at half the rotational speed.

A swing arm 36 is pivotally supported on the cylinder block 3 so as to be vertically swingable at a position closer to the cylinder 8 than the camshaft 31, and a cam follower 37 of the swing arm 36 comes into contact with the camshaft 31 for intake. Valve 28, exhaust valve
Rocker shaft located near V bank 15 from the top of 29
A push rod 38 is interposed between a rocker arm 40 and a swing arm 36 that are pivotally fitted to the rocker shaft 39 and a push rod 38 is interposed. When the cam shaft 31 is rotationally driven, the cam shaft 31 The swing arm 36 in contact with the cam follower 37 is vertically swung, and the swing motion of the swing arm 36 is transmitted to the rocker arm 40 via the push rod 38, and the swing motion of the rocker arm 40 causes intake air. The valve 28 and the exhaust valve 29 are adapted to be opened intermittently.

Further, each intake port 16 is provided with a fuel injection valve 41 directed to the intake opening 18, and is located between the intake opening 18 of the intake port 16 and the exhaust opening 19 of the exhaust port 17, A spark plug 42 is provided, and the spark generated by the spark plug 42 ignites the air-fuel mixture in the combustion chamber 43.

Further, as shown in FIGS. 1 and 6, an edge portion 44 is formed at the front end portion (one end portion with respect to the vehicle body) of the cylinder block 3 and the crankcase 6, and the edge portion 44 is formed. A cover member 45 is detachably attached to the portion 44, and as shown in FIG. 3, the top ends of the inner wall portions 46 of the left and right cylinder rows of the cylinder block 3 and the front and rear end wall portions 47 shown in FIG. A top plate 48 is integrally attached to the top end by a bolt 49, and the crank chamber 50 is sealed by the oil pan 7, the cover member 45 and the top plate 48.

As shown in FIGS. 3 and 6, a partition plate 51 is integrally attached to the lower surface of the top plate 48, and the breather chamber 52 sealed by the top plate 48 and the partition plate 51 is cranked through an opening 53. The chamber 50 is communicated with the intake chamber 21 or a canister containing an adsorbent (not shown) via a connecting pipe 54 and a connecting pipe (not shown) fitted to the connecting pipe 54.

Further, as shown in FIG. 6, a pulsar rotor 55 is integrally mounted on the cam shaft 31 adjacent to the driven sprocket 33, and a pickup coil 56 is attached to the cover member 45 adjacent to the outer periphery of the pulsar rotor 55. It is attached integrally.

Further, as shown in FIG. 2, the casing of the lubricating oil pump 59 is constituted by the cover member 45 and the back plate 58 integrally mounted on the inner surface of the cover member 45 with the screw 57. The rotor 60 in the casing is integrally fitted to the front end of the crankshaft 10.

Further, the suction port 61 of the lubricating oil pump 59 is connected to the strainer 64 via the pipe 63, and the discharge port 62 of the lubricating oil pump 59 is connected to the outer space 66 of the filter 65, When the crankshaft 10 rotates and the lubricating oil pump 59 is rotationally driven, the oil accumulated in the oil pan 7 is sucked into the lubricating oil pump 59 from the strainer 64 via the pipe 63, and the lubricating oil is pumped. The oil pressurized by the pump 59 is discharged from the discharge port.
It is discharged from 62 to the outer space 66 of the filter 65, filtered by the element 67, and then from the inner space 68 to the overhead valve type V type 4.
It is adapted to be supplied to each lubricated portion of the cylinder internal combustion engine 1.

Also, as shown in FIG. 2, the crankshaft
A drive pulley 70 is integrally fitted to the front end of the bolt 10 with a bolt 69, and is disposed on the first pulley portion 71 of the drive pulley 70 and the right side of the crankshaft 10 (left side in FIG. 1, front with respect to the vehicle body). Further, the first endless belt 82 is bridged between the driven pulley 75 of the air conditioner compressor 74 and the driven pulley 77 of the water pump 76 disposed above the crankshaft 10 and the air conditioner compressor 74. A thermostat 79 is interposed in a suction port 78 of 76, and a discharge port 80 of the water pump 76 communicates with a cooling water suction opening 81 near the left and right cylinders 8 in the cylinder block 3.

Further, an AC generator 83 is disposed on the left side (right side in FIG. 1) opposite to the air conditioner compressor 74 with the crankshaft 10 interposed therebetween, and the driven pulley 84 of the AC generator 83 is disposed.
The second endless belt 85 is bridged between the drive pulley 70 and the second pulley portion 72 of the drive pulley 70, and the power steering oil pump 86 is disposed above the driven sprocket 33 of the camshaft 31. A third endless belt 88 is spanned between a driven pulley 87 of a vehicle oil pump 86 and a third pulley portion 73 of a drive pulley 70. When the crankshaft 10 rotates, an AC generator 83 and a power steering oil pump 86 are provided. Is driven to rotate.

Further, as shown in FIG. 2, a flywheel 89 is integrally attached to the rear end (right end in FIG. 2) of the crankshaft 10, and the input shaft (shown in the drawing) of the transmission 2 of the flywheel 89 is shown. The output shaft 90 (see FIGS. 1 and 3) of the transmission 2 is positioned parallel to the crankshaft 10, and the output shaft 90 is connected to the front wheel of the vehicle through a transmission mechanism (not shown). When the crankshaft 10 is rotated (not shown), the transmission 2 shifts the gear to a required gear ratio and then the power is transmitted to the front wheels.

Moreover, the crankshaft is adjacent to the fuel injection valve 41.
The fuel pipe 91, which is installed in parallel with the fuel pipe 10, is connected to the upper end of the fuel injection valve 41, is sucked up from a fuel tank (not shown), and circulates in the fuel pipe 91 by a fuel pump (not shown). Are supplied to the fuel injection valve 41.

Reference numeral 92 is an oil level gauge.

Since the embodiment shown in FIGS. 1 to 6 is constructed as described above, when the overhead valve V-type 4-cylinder internal combustion engine 1 is cranked, it is filtered by an air cleaner (not shown). The filtered air is adjusted to a required intake air amount by the throttle valve device 27, is sucked into the intake chamber 21, flows from the intake chamber 21 into the intake port 16 through the intake pipe 20, and is required by the valve operating device 30. The fuel is supplied to the combustion chamber 43 through the opened intake valve 28 at the timing of, and the fuel is supplied from the fuel injection valve 41 to the combustion chamber 43 through the intake port 16 at the same timing. Valve 28
After the valve is opened, the air-fuel mixture is ignited by the spark generated from the ignition plug 42 at a required timing.

The piston 9 is pushed down by the combustion gas which is ignited and burned, and the crankshaft 10 starts rotating,
The power is transmitted to the wheels of the passenger car through the transmission 2, and the passenger car can travel.

The exhaust combustion gas combusted in the combustion chamber 43 flows from the exhaust port 17 into the exhaust gas purifying device 25 through the exhaust branch pipe 23 and the exhaust pipe 22, and the exhaust gas purifying device 25
The catalyst in 25, NO _X, harmful gases such as CO is removed is released into the atmosphere, but the exhaust pipe 22 and an exhaust branch pipe 23 is heated to a high temperature by the exhaust hot gases of combustion flowing therein, Since the outer peripheries of the exhaust pipe 22 and the exhaust branch pipe 23 are sealed by a heat insulating pipe 24, the intake pipe 20, the intake chamber 21, and the throttle valve device 27 are located above the exhaust pipe 22 and the exhaust branch pipe 23. However, these intake systems are not heated by the influence of the exhaust combustion gas flowing in the exhaust pipe 22 and the exhaust branch pipe 23, and the charging efficiency can be maintained at a high level.

Further, since the exhaust pipe 22 and the exhaust branch pipe 23 are not cooled significantly and are kept at a high temperature by the heat insulating pipe 24, the exhaust combustion gas flowing from the exhaust pipe 22 into the exhaust gas purifying device 25 is Sufficient oxidation / reduction reaction occurs with the catalyst in the exhaust gas purification device 25, and the emission of harmful gas is extremely small.

Furthermore, since only one exhaust gas purification device 25 is required, the cost can be reduced.

The intake valve 28 and the exhaust valve 29 are located closer to the V bank 15 from the center of each cylinder 8 and are arranged in a substantially straight line along the arrangement direction of the cylinders 8, that is, the longitudinal direction of the crankshaft 10 to operate the valve valves. Since the device 30 is driven by one camshaft 31, the structure of the valve operating device 30 is remarkably simplified, and the weight and cost can be greatly reduced.

Further, a lubricating oil pump 59 is provided at the shaft end of the crankshaft 10, a pulsar rotor 55 and a power steering oil pump 86 are arranged above the lubricating oil pump 59, and air conditioner compressors 74 are provided on both left and right sides of the lubricating oil pump 59. And the alternator 83 is arranged, the pulsar rotor
Since the water pump 76 is arranged substantially in the middle connecting the 55 and the air-conditioning compressor 74, these auxiliary machines are compactly assembled.

In the embodiment shown in FIGS. 1 to 6, the intake opening 18 and the exhaust opening 19 are provided for each cylinder 8.
One is provided in a straight line from the center of the cylinder toward the V bank 15, but as shown in FIG. 7, two intake openings 18 are provided from the center of the cylinder 8 to the outside and an exhaust opening 19 of the cylinder 8 is provided. Two pieces may be provided near the V bank 15 from the center. Even in such an embodiment, since the lengths of the exhaust pipe 22 and the exhaust branch pipe 23 are short and compact, the heat radiation of the combustion gas is minimized. Therefore, the catalytic action in the exhaust gas purification device 25 can be sufficiently performed, and the heat transfer to the intake air can be suppressed.

The present invention is also applicable to an overhead valve V-type 4-cylinder internal combustion engine 1 having four cylinders on one side and a total of eight cylinders as shown in FIG.

[Brief description of drawings]

FIG. 1 is a front view illustrating an embodiment of an intake / exhaust structure for an overhead valve type V four-cylinder internal combustion engine according to the present invention.

FIG. 2 is a vertical sectional side view cut along a line II-II in FIG.

3 is a partial vertical cross-sectional view taken along the line III-III of FIG.

FIG. 4 is a plan view of FIG. 1;

5 is a view taken along the line VV of FIG.

6 is a vertical sectional side view cut along a line VI-VI in FIG.

FIG. 7 is a plan view of another embodiment of the present invention.

FIG. 8 is a plan view of still another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Overhead valve type V-4 internal combustion engine, 2 ... Transmission, 3 ...
Cylinder block, 4 ... Cylinder head, 5 ... Head cover, 6 ... Crank case, 7 ... Oil pan, 8 ... Cylinder, 9 ... Piston, 10 ... Crank shaft, 11 ... Crank pin, 12 ... Journal bearing, 13 ... Crank shaft holder ,14…
Connecting lot, 15 ... V bank, 16 ... Intake port, 17 ... Exhaust port, 18 ... Intake opening, 19 ... Exhaust opening, 20
Intake pipe, 21 ... Intake chamber, 22 ... Exhaust pipe, 23 ... Exhaust branch pipe, 24 ... Insulation pipe, 25 ... Exhaust gas purifying device, 26 ... Intake pipe, 27 ... Throttle valve device, 28 ... Intake valve, 29 ... Exhaust valve, 30 ... Valve operating device, 31 ... Cam shaft, 32 ... Drive sprocket, 33
... driven sprocket, 34 ... cam chain, 35 ... chain tensioner, 36 ... swing arm, 37 ... cam follower, 38 ... push rod, 39 ... rocker shaft, 40 ... rocker arm, 41 ... fuel injection valve, 42 ... spark plug, 43 ... Combustion chamber, 44 ... Edge portion, 45 ... Cover member, 46 ... Inner side wall portion, 47 ... Front and rear end wall portion, 48 ... Top plate, 49 ... Bolt, 50 ... Crank chamber, 51
… Partition plate, 52… Breather chamber, 53… Opening, 54… Connecting pipe, 55
... Pulser rotor, 56 ... Pickup coil, 57 ... Screw, 58 ... Back plate, 59 ... Lubrication oil pump, 60 ... Rotor,
61 ... Suction port, 62 ... Discharge port, 63 ... Pipe, 64 ... Strainer, 65 ... Filter, 66 ... Outer space, 67 ... Element, 68 ... Inner space, 69 ... Bolt, 70 ... Drive pulley, 71 ... First pulley Part, 72 ... Second pulley part, 73 ... Third pulley part, 74 ... Air conditioner compressor, 75 ... Driven pulley, 76 ... Water pump, 77 ... Driven pulley, 78
… Inhalation port, 79… Thermostat, 80… Discharge port,
81 ... Cooling water suction opening, 82 ... First endless belt, 83 ... Alternator, 84 ... Driven pulley, 85 ... Second endless belt, 86 ...
Oil pump for power steering, 87 ... Driven pulley, 88 ... Third endless belt, 89 ... Flywheel, 90 ... Output shaft, 91 ... Fuel pipe, 92 ... Oil level gauge.

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[Procedure amendment]

[Submission date] October 11, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

Since the embodiment shown in FIGS. 1 to 6 is constructed as described above, when the overhead valve V-type 4-cylinder internal combustion engine 1 is cranked, it is filtered by an air cleaner (not shown). The filtered air is adjusted to a required intake air amount by the throttle valve device 27, and the intake chamber 2
1 is introduced into the combustion chamber 43 from the intake chamber 21 through the intake pipe 20 into the intake port 16, and is supplied to the combustion chamber 43 through the opened intake valve 28 at a required timing by the valve operating device 30. but is supplied fuel to the combustion chamber 43 through the intake port 16 from the fuel injection valve 41 together with this timing, after closing valve of the intake valve 28, the air-fuel mixture is generated from the ignition plug 42 at a predetermined timing It is ignited by sparks.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area F01N 7/10 F02M 35/116 35/10

Claims (4)

[Claims] 1. An overhead valve V-type multi-cylinder internal combustion engine in which two groups of cylinders are arranged in a V shape and a transmission is integrally provided at one shaft end of a crankshaft of the internal combustion engine, Exhaust pipes connected to the exhaust ports of the respective cylinders and collected are arranged in a V bank sandwiched between the two rows of V-shaped cylinder groups and are configured to have an adiabatic structure against the outside air. An exhaust gas purification device connected to the exhaust end of the pipe is disposed on the transmission, and the intake pipes connected to the intake ports of the respective cylinders and collected are located at a position higher than the exhaust pipe in the V bank. An intake / exhaust structure for an overhead valve type V multi-cylinder internal combustion engine. 2. The number of cylinders is set to a multiple of 4, one intake port and one exhaust port are arranged in parallel with the cylinder row for each cylinder, and the exhaust ports of two adjacent cylinders are close to each other. 2. The branch exhaust pipes are respectively connected to the adjacent exhaust ports and are assembled together.
An intake / exhaust structure for an overhead valve V-type multi-cylinder internal combustion engine as described. 3. The number of cylinders is set to a multiple of 4, two intake ports and two exhaust ports are provided for each cylinder, and the exhaust ports are arranged near the V-shaped space, and adjacent two cylinders are provided. 2. The intake / exhaust structure for an overhead valve V-type multi-cylinder internal combustion engine according to claim 1, wherein branch exhaust pipes are connected to the exhaust ports of and are mutually assembled. 4. The overhead valve V-type multi-cylinder internal combustion engine according to claim 1, wherein the fuel injection valve and the spark plug are arranged outside the V-shaped space with respect to the intake valve while being oriented parallel to each other. organ.