JPH0598969A - Intake device for v-shaped multicylinder engine - Google Patents

Abstract

PURPOSE:To arrange intake device which carries out both inertia supercharge and resonance supercharge between cylinder lines of a V-shaped multicylinder engine. CONSTITUTION:A pair of distribution chambers 111, 112 are arranged between cylinder lines 21 and 22, of a V-shaped multicylinder engine 1. The distribution chambers 111, 112 are connected to the far side cylinder lines 2 @ and 22, by means of long main intake pipes 131, 132, while connected to the near side cylinder lines 22, 21 by means of bypass intake pipes 131, 132. The main intake pipes 121, 122 and the bypass intake pipes 131, 132 are changed over to each other by means of pipe length changeover valves 15, 15 provided inside the bypass intake pipes 131, 132. Communication between the distribution chambers can be interrupted at a large-diameter communication passage 17 provided with an opening/closing valve 18. The distribution chambers 111, 112 are connected to a collection chamber 21 through resonance pipes 201, 202.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for supplying intake air to each combustion chamber of a V-type multi-cylinder engine, and more particularly to a V-type which utilizes inertial supercharging and resonance supercharging. The present invention relates to an intake device for a multi-cylinder engine.

[0002]

2. Description of the Related Art In an engine, the output can be improved by increasing the intake charging efficiency. Inertial supercharging, resonance supercharging, and the like are known as methods for increasing the intake charge efficiency. Inertial supercharging uses the inertia of the intake flow generated by opening the intake valve so that the intake air is pushed into the combustion chamber in the latter half of the intake stroke. When the intake valve is opened, the negative pressure in the combustion chamber that accompanies the downward movement of the piston accelerates the air column in the intake path toward the combustion chamber. Then, due to the inertia, the intake air continues to flow into the combustion chamber even when the lowering of the piston is completed. That is, it is supercharged. By using such inertial supercharging, the charging efficiency can be easily increased only by tuning the intake system. Moreover, the engine speed range in which the intake inertia effect is suitable is relatively wide. For this reason, this inertia supercharging is widely used as an effective method for improving the output of the engine.

On the other hand, in resonance supercharging, a plurality of cylinders having different intake valve opening timings are connected to one chamber equipped with a resonance pipe by independent intake pipes, respectively, and pressure vibrations generated in the chambers and each cylinder are connected. It is intended to improve the intake charging efficiency by synchronizing with the intake cycle. A chamber equipped with a resonance tube has a natural frequency determined by the volume of the chamber and the length and diameter of the resonance tube. Therefore, when the opening / closing cycle of the intake valve of each cylinder matches its natural frequency, maximum pressure is generated in the chamber when the intake valve is open, and a large supercharging effect can be obtained.

By the way, in the case of inertia supercharging, during continuous engine operation, the intake charge efficiency becomes maximum when the cycle of intake pulsation occurring in the intake system matches the intake valve opening time. That is, the tuning point of inertia supercharging is determined by the effective pipe length and cross-sectional area of the intake path. Therefore, if the length and diameter of the intake path are constant, the supercharging effect can be obtained only when the engine speed is within a certain range. As described above, the applicable range is quite wide, but when used in an extremely wide engine speed range such as an automobile engine, the engine speed range in which the inertial effect is obtained is limited. In order to always obtain a high charging efficiency by inertial supercharging, it is necessary to change the intake pipe length or the cross-sectional area according to the engine speed. Therefore, conventionally, for example, as shown in Japanese Utility Model Publication No. 58-56330, a long intake pipe and a short intake pipe are provided in an intake passage for supplying intake air from a distribution chamber to one combustion chamber, and those intake pipes are provided. There has been proposed a variable inertia supercharging intake device in which a switching valve is used to switch depending on the engine speed. According to such an intake device, intake air is supplied through a long intake pipe at low engine speeds, and intake air is supplied through a short intake pipe at high engine speeds, so that the engine can operate in either a low speed range or a high speed range. In this way, a high intake inertia effect can be obtained, and the output torque of the engine can be increased.

[0005]

However, in the case of an automobile engine, since the engine speed range used as described above is extremely wide, the two ranges of the engine low speed range and high speed range are as described above. Even if a portion corresponding to the inertial effect is formed, the torque characteristic curve becomes a deep valley in the medium speed region of the engine, and there is a problem that a high output torque cannot be obtained. If the inertia effect is obtained in the middle speed range of the engine, such a valley of the torque curve can be shallow, but instead, the output torque in the low speed range or the high speed range of the engine decreases. Resulting in. Therefore, it is difficult to obtain a flat and high torque characteristic in the entire engine speed region only by inertial supercharging.

On the other hand, in the case of resonance supercharging, the engine speed at which the resonance effect is obtained is determined by the natural frequency of the intake system, that is, the volume of the chamber acting as a resonance box and the length and diameter of the resonance tube. become. Therefore, when they are constant, the resonance effect can be obtained only when the engine speed is in a constant range. In addition, the engine speed region where the resonance effect is obtained, that is, the resonance supercharging adaptation region is narrow. And if it deviates from the area | region, filling efficiency will fall rather. Therefore, even with this resonance supercharging, it is not possible to obtain a high output torque over the entire engine speed range.

The inventors of the present invention thought that the output could be improved in a wider engine speed range by combining the variable inertia supercharging and the resonance supercharging as described above. For example, if the inertia supercharging adaptive region is set to the low speed region and the high speed region of the engine, and the resonance supercharging adaptive region is set to the medium speed region that is the valley of torque, the low speed region to the high speed region of the engine can be set. It is possible to obtain a flat and high torque characteristic up to. However, in order to do so, it is necessary to provide a large number of intake pipes and chambers. Moreover, since the length of the intake path becomes long, it is required that the intake pipe and the like be as straight as possible in order to prevent an increase in intake resistance. Therefore, the layout of the intake system becomes extremely difficult.

In the case of a V-type multi-cylinder engine, each cylinder row is generally composed of cylinders having different intake valve opening timings. Moreover, a space is formed between the cylinder rows. Therefore, it is considered possible to obtain the intake device that combines the variable inertia supercharging and the resonance supercharging as described above, if the space is used effectively. The present invention has been made by paying attention to the characteristics of such a V-type multi-cylinder engine, and an object thereof is to improve the output in the entire engine speed region. It is to provide a device.

[0009]

In order to achieve this object, the present invention provides a pair of distribution chambers corresponding to each cylinder row of a V-type multi-cylinder engine, and the distribution chambers are provided in each cylinder row. Along the main intake pipe, the distribution chamber and the combustion chambers of the cylinders belonging to the cylinder row farther from the distribution chamber are arranged along the distribution chamber and the cylinders on the side closer to the distribution chamber. Each cylinder belonging to the row is connected by a short bypass intake pipe. The main intake pipe and the bypass intake pipe connected to each cylinder are switched by a pipe length switching valve. Further, the distribution chambers are communicated with or blocked from each other by a large-diameter communication passage having an opening / closing valve. Each distribution chamber is connected to the collecting chamber via an independent resonance tube.

[0010]

With this configuration, when the main intake pipe and the bypass intake pipe are switched by the pipe length switching valve, each cylinder is connected to the distribution chamber via the long main intake pipe or the short bypass intake pipe. As a result, the intake inertia effect can be obtained in the engine rotation range corresponding to each. In addition, if the distribution chambers are shut off by an on-off valve, the intake system of each cylinder group becomes independent, and a resonance effect can be obtained in the engine speed region corresponding to the natural frequency of the intake system. .. Therefore, for example, if the resonance effect is obtained in the low speed range of the engine and the intake inertia effect is obtained in the medium speed range and the high speed range, the intake charging efficiency is increased in the entire rotation range of the engine and the intake charge efficiency is flat. A high torque characteristic curve can be obtained. And each distribution chamber is V
By being respectively arranged along each cylinder row of the multi-cylinder engine, one distribution chamber is located far away from the other cylinder row. Therefore, if the cylinders of one cylinder row and the respective distribution chambers are connected by the intake pipes, respectively, even if those intake pipes are straight, one intake pipe becomes long and the other intake pipe becomes It gets shorter. That is, it becomes easy to provide long and short intake pipes, and moreover, they can be made straight. Further, since the pair of distribution chambers are arranged close to each other, the communication passage communicating between the distribution chambers is shortened, and the influence of the communication passage can be suppressed to be small.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of an intake device for a V-shaped multi-cylinder engine according to the present invention. FIG. 1 is a cutaway front view of a main part of the engine, and FIG. 2 is a schematic plan view thereof. As is clear from these figures, this engine is a V-type 6-cylinder engine, and the engine body 1 has a pair of cylinder rows, that is, a first cylinder row 2 ₁ and a second cylinder row 2 ₂ in a left-right V-shape. It is arranged open. In each cylinder row 2 ₁ , 2 ₂ ,
Three cylinders 3 ₁ , 3 ₁ , 3 ₁ ; 3 ₂ , 3 ₂ , 3
₂ are arranged in the axial direction of the crankshaft (not shown). A cylinder head 5 is attached to the upper surface of the cylinder block 4 in which the cylinder 3 ₁ or 3 ₂ is formed. A combustion chamber 6 is provided on the bottom surface of the cylinder head 5 at a position facing the cylinders 3 ₁ and 3 ₂ . An intake port 7 and an exhaust port 8 that open to the combustion chamber 6 are provided inside the cylinder head 5, and the openings of the ports 7 and 8 on the combustion chamber 6 side are the intake valve 9 and the exhaust gas, respectively. It is designed to be opened and closed by the valve 10. Three cylinders 3 ₁ , 3 ₁ , 3 ₁ or 3 respectively belonging to each cylinder row 2 ₁ or 2 _2.
Intake valves 9, 9, 9 of ₂ , 3 ₂ , 3 ₂ have opening timings
They have a phase difference of 120 ° so that they do not overlap each other. The inlet of the intake port 7 is open to the upper side surface of the cylinder head 5 located on the valley side between the cylinder rows 2 ₁ and 2 ₂ , and the outlet of the exhaust port 8 is open to the other side surface of the cylinder head 5. ..

A first distribution chamber 11 ₁ and a second distribution chamber 11 ₂ are arranged in parallel between the cylinder rows 2 ₁ and 2 ₂ . These first and second distribution chambers 11
₁ and 11 ₂ are the first and second cylinder rows 2 ₁ and 2 _{2 respectively.}
It is supposed to be located on the side far from. And the first
The distribution chamber 11 ₁ and the intake ports 7, 7, 7 of the first cylinder row 2 ₁ are connected to each other via independent main intake pipes 12 ₁ , 12 ₁ , 12 ₁ each having a relatively small diameter and long. In addition, the second distribution chamber 11 ₂ and the intake ports 7, 7, 7 of the second cylinder row 2 ₂ have the same main intake pipe 12 ₂ ,
It is connected via 12 ₂ and 12 ₂ . Further, the second distribution chamber 11 ₂ and each intake port 7 of the first cylinder row 2 ₁ ,
7 and 7 are connected via independent bypass intake pipes 13 ₁ , 13 ₁ and 13 ₁ each having a relatively large diameter. Similarly, the first distribution chamber 11 ₁ and the second cylinder row 2 ₂
The intake ports 7, 7 and 7 are connected to the intake ports 7 and 7 via bypass intake pipes 13 ₂ , 13 ₂ and 13 ₂ , respectively. Main intake pipes 12 ₁ and 12 ₂ and bypass intake pipes 13 ₁ and 13
Both ₂ are considered to be almost straight. One end of each of the main intake pipes 12 ₁ and 12 ₂ is opened to the lower surface of each of the distribution chambers 11 ₁ and 11 ₂ , and the other end thereof is an end of the bypass intake pipes 13 ₁ and 13 _{2 on} the cylinder head 5 side, that is, its ends. It is designed to open at the downstream end.
Therefore, the intake air flowing through the main intake pipes 12 ₁ and 12 ₂ and the intake air flowing through the bypass intake pipes 13 ₁ and 13 ₂ join at the downstream end. At the ends of the bypass intake pipes 13 ₁ and 13 ₂ , each intake port 7,
7, ... Fuel injection nozzle 14 for injecting fuel toward the inside,
14, ... Are attached.

Further, a bypass intake pipe 13 _1, 13 on an end portion of the _second distribution chamber 11 _2, 11 ₁ side, pipe length switching valve can open and close the bypass intake pipe 13 _1, 13 ₂ 15,1
5, ... are provided. This pipe length switching valve 15,15,
... is a butterfly type, and each three bypass intake pipes 1
The three valves 15 provided on 3 ₁ and 13 ₂ are interlocked,
The actuators 16 and 16 are adapted to be simultaneously opened and closed. When the engine speed reaches a predetermined high speed, the actuator 16 is operated relatively slowly according to the change in the speed, and in the high speed range of the engine, the pipe length switching valve 15 is opened and rotations below that are performed. In the area, the valve 15 is closed. Therefore, the pipe length switching valve 15 has an intermediate opening degree according to the rotational speed at that time in the engine rotational speed region from fully closed to fully opened. Then, the main intake pipe 12 ₁ ,
The length and diameter of 12 ₂ are set so that the intake inertia effect is maximized at a predetermined engine speed Nm in the medium speed range of the engine, and the lengths and diameters of the bypass intake pipes 13 ₁ and 13 ₂ are Is set so that the intake inertia effect is maximized at a predetermined rotation speed Nh in the high speed range.

First and second distribution chambers 11 ₁ , 11 ₂
Are connected to each other by a large-diameter communication passage 17.
The communication passage 17 has a butterfly-type on-off valve 18
It is designed to be opened and closed by. This on-off valve 18
Is relatively slowly opened and closed according to a change in the engine speed by an actuator 19 that operates when the engine speed becomes equal to or higher than a predetermined low speed, and cuts off the communication passage 17 in the low engine speed range. In the above rotation range, the communication passage 17 is made conductive. For the sake of convenience, in the figure, the communication passage 17 is indicated by the bypass intake pipes 13 ₁ , 13 _2.
It is said that the diameter is about the same as that of and is relatively long, but in reality, the diameter is as large as possible and the length is as short as possible. However, if the diameter is increased, the on-off valve 18 also needs to be large, and the actuator 19 becomes large. Therefore, when it is not desirable to make the diameter of the communication passage 17 too large, the communication passage 17 is divided into a plurality of passages, and the communication passages 17 are simultaneously opened and closed by the multiple open / close valve 18. ..
In addition, the first and second distribution chambers 11 ₁ and 11 ₂ extend from one end thereof, are inverted, and extend through the valley between the cylinder rows 2 ₁ and 2 ₂ to the other end side. The pipes 20 ₁ and 20 ₂ allow a small volume of the collecting chamber 21.
It is connected to the. The lengths and diameters of the resonance tubes 20 ₁ and 20 ₂ are set so that the maximum resonance effect can be obtained at a predetermined rotation speed Nl in the low speed region of the engine together with the volumes of the distribution chambers 11 ₁ and 11 _2. ing. A throttle body 22 is attached to the collecting chamber 21, and after the intake air sucked from an air cleaner (not shown) is measured by the throttle valve 23, the collecting chamber 21
Has been introduced to.

Next, the operation of the intake system thus constructed will be described. When the engine is running at low speed, both the pipe length switching valve 15 and the on-off valve 18 are closed, and the bypass intake pipes 13 ₁ and 13 ₂ and the distribution chambers 11 ₁ and 11 are closed.
All the communication passages 17 between the _two are cut off. Therefore, the intake air introduced into the collecting chamber 21 from the air cleaner through the throttle body 22 is supplied to the pair of resonance tubes 20.
₁ , 20 ₂ and are introduced into the first and second distribution chambers 11 ₁ and 11 ₂ , respectively. Then, in each of the distribution chambers 11 ₁ and 11 ₂ , it is distributed to the three main intake pipes 12 ₁ and 12 ₂ , respectively, and the corresponding cylinder rows 2 ₁ and 2 ₂ are distributed.
Through the intake port 7 of the combustion chamber 6 of each cylinder 3 ₁ , 3 _2.
Be led to. During this time, fuel is injected from the fuel injection nozzle 14 and the fuel is supplied to the combustion chamber 6 together with the intake air.

By the way, such a flow of intake air is caused by the intake stroke of each cylinder 3 ₁ , 3 ₂ . At this time, the intake system on the downstream side of the collecting chamber 21 is independent for each of the cylinder rows 2 ₁ and 2 ₂ . Moreover, 3 belonging to each cylinder row 2 ₁ , 2 ₂
The cylinders 3 ₁ , 3 ₁ , 3 ₁ ; 3 ₂ , 3 ₂ , 3 ₂ have their intake valve 9 opening timings having a phase difference of 120 °. Therefore, when a certain cylinder 3 ₁ , 3 ₂ enters the intake stroke, the pressure wave generated in that cylinder 3 ₁ , 3 ₂ is distributed from the main intake pipes 12 ₁ , 12 ₂ to the distribution chamber 11 ₁ ,
Propagate to the collecting chamber 21 through 11 ₂ and the resonance tubes 20 ₁ and 20 ₂ . As a result, the distribution chamber 11 ₁ ,
Pressure oscillation occurs in 11 ₂ . In that case, the resonance tube extends from the collection chamber 21 to the distribution chamber 11 _1, 11 ₂ 2
0 ₁ and 20 ₂ are set to a sufficiently long predetermined length. The volumes of the distribution chambers 11 ₁ and 11 ₂ are also set to a predetermined size. Therefore, the resonance tube 20
_The intake air flowing from ₁ , 20 ₂ into the distribution chambers 11 ₁ , 11 ₂ will have a relatively low predetermined natural frequency. As a result, in the low engine speed range, resonance occurs between the main intake pipes 12 ₁ and 12 ₂ and the distribution chambers 11 ₁ and 11 _2, and the intake air is accompanied by the pressure oscillation of the combustion chamber 6 and the intake air.
It will be pushed inside. In this way, the resonance effect works and the intake charging efficiency is enhanced. At this time, the pressure wave in _one resonance tube 20 _{1 and} the pressure wave in the other resonance tube 20 ₂ have opposite directions. Further, since the collecting chamber 21 has a small volume, the damping of the pressure vibration by the collecting chamber 21 is small. Therefore, a pressure wave directed to the collecting chamber 21 in _one resonance tube, for example, 20 ₁ , is transmitted to the other resonance tube 20 ₂ .
In the resonance tube 20 ₂ , the pressure wave toward the distribution chamber 11 ₂ is strengthened. As a result, a large supercharging effect can be obtained even in the low speed rotation range of the engine, and the intake charging efficiency is further improved. Thus, the torque characteristic curve of the engine at this time has a peak at a low engine speed Nl, as indicated by I in FIG. That is, the output torque of the engine becomes high in the low speed range.

When the engine speed increases and exceeds a predetermined medium speed, the actuator 19 operates and the on-off valve 18 gradually opens. As a result, the first and second distribution chambers 11 ₁ and 11 ₂ communicate with each other through the communication passage 17 and operate like one distribution chamber. Thus, each cylinder 3 _1, 3 ₂ pressure wave generated from is canceled by the distribution chamber 11 _1, 11 _2, the resonance effect will not occur. However, at this time as well, the pipe length switching valve 15 is closed, and the intake air is distributed to the distribution chamber 11
₁ and 11 ₂ are led to the cylinders 3 ₁ and 3 ₂ through relatively long main intake pipes 12 ₁ and 12 ₂ . Then, the main intake pipes 12 ₁ and 12 ₂ are set to a size capable of obtaining an intake inertia effect in the medium speed range of the engine. Therefore,
At this time, the intake charging efficiency is increased by the inertial effect. Thus, the torque characteristic curve of the engine at this time becomes a curve having a peak at the medium speed engine speed Nm, as indicated by II in FIG. That is, the output torque of the engine becomes high in the medium speed range.

When the engine speed further increases and exceeds a predetermined high speed, the actuator 16 operates and the pipe length switching valve 15 gradually opens. As a result, the bypass intake pipes 13 ₁ and 13 ₂ are electrically connected. Therefore, the intake air introduced into the distribution chambers 11 ₁ and 11 ₂ is supplied to the main intake pipe 12
Not only is it distributed to ₁ , 12 ₂ , but it is also distributed to the bypass intake pipes 13 ₂ , 13 ₁ . Then, the intake air that has flowed into the bypass intake pipes 13 ₁ and 13 ₂ merges with the intake air that has been guided through the corresponding main intake pipes 12 ₁ and 12 ₂ , and is supplied to the combustion chamber 6 of each cylinder 3 ₁ and 3 _2. It At this time, the bypass intake pipes 13 ₁ and 13 ₂ are
Since the pipe length is shorter and the cross-sectional area is larger than those of 2 ₁ and 12 ₂ , the flow of intake air guided to each cylinder 3 ₁ and 3 ₂ is that which flows through the bypass intake pipes 13 ₁ and 13 _2. Become dominant. That is, the bypass intake pipes 13 ₁ and 13 ₂ have a strong influence on the pipe length. Since the bypass intake pipes 13 ₁ and 13 ₂ are set to have a length that allows the intake inertia effect to be obtained in the high speed region of the engine, at this time, the intake charging efficiency is increased by the inertia effect. The torque curve of the engine at this time is a curve having a peak at a high engine speed Nh, as indicated by III in FIG. That is, the output torque of the engine becomes high in the high speed range.

When the opening / closing valve 18 is opened in the medium speed range or the high speed range of the engine in this way, the distribution chambers 11 ₁ and 11 ₂ are communicated by the communication passage 17, so that the communication passage is formed. Pressure vibration will also occur at 17. However, since the diameter of the communication passage 17 is sufficiently large and short, the frequency of the pressure vibration is extremely high. Therefore, the pressure oscillation does not affect the intake air flowing through the main intake pipes 12 ₁ and 12 ₂ or the bypass intake pipes 13 ₁ and 13 ₂ . Since the distribution chambers 11 ₁ and 11 ₂ are arranged between the cylinder rows 2 ₁ and 2 _{2 of the} V-shaped multi-cylinder engine, the communication passage 17 can be shortened as such. Further, since the length is shortened as described above, it is possible to prevent the weight from being significantly increased even if the diameter is increased.

In this way, according to this intake device,
High output torque can be obtained in any of the low speed range, the middle speed range, and the high speed range of the engine. And
Between the low speed range, the medium speed range, and the high speed range, the butterfly type on-off valve 18 or the pipe length switching valve 15 passes through the half open state, so that the resonance effect or the intake inertia effect gradually appears. Therefore, the torque characteristic curve of the engine becomes a flat curve with shallow valleys as shown by the thick line in FIG. 3, and shock does not occur at the time of switching.

The first distribution chamber 11 ₁ is arranged on the second cylinder row 2 ₂ side, and the second distribution chamber 11 ₂ is arranged as the first distribution chamber 11 ₂ .
The main intake pipes connecting the distribution chambers 11 ₁ and 11 ₂ and the combustion chambers 6 of the cylinders 3 ₁ and 3 ₂ belonging to the cylinder columns 2 ₁ and 2 ₂ respectively are arranged on the cylinder column 2 ₁ side. 12
_{Although 1} and 12 ₂ are straight, they can be made sufficiently long. Therefore, the intake resistance can be suppressed to a low level, and the output can be further improved especially in the low speed range of the engine. Also, a pair of distribution chambers 11
₁ , 11 ₂ are a pair of cylinder rows of a V-type multi-cylinder engine 2, 2
The distribution chamber 11 ₁ ,
Since the distance between 11 ₂ is small, the communication passage 17 for communicating between them can be shortened as described above. Furthermore, the resonance tubes 20 ₁ and 20 ₂ connected to the distribution chambers 11 ₁ and 11 ₂ can also be arranged between the cylinder rows 2 ₁ and 2 ₂ . Therefore, the space between the cylinder rows 2 ₁ and 2 _{2 of} the V-type multi-cylinder engine is effectively used, and the entire engine can be made compact.

[0022] In the above embodiments, the resonance effect occurs at low speeds of the engine, but the intake inertia effect in the medium speed range and high speed range is to occur, the main intake pipe 12 _1, 12
₂ , bypass intake pipes 13 ₁ and 13 ₂ or resonance pipe 2
0 ₁ , 20 ₂ pipe length and diameter, pipe length switching valve 15 and open / close valve 1
By appropriately setting the opening / closing timing of 8 and the like, an intake inertia effect can be obtained in the low speed range and the high speed range of the engine, and the valley of the torque curve in the middle speed range therebetween can be supplemented by the resonance effect or the low speed range of the engine. It is also possible to make the intake inertia effect work in the high speed range and the middle speed range, and the resonance effect in the high speed range. Further, by appropriately setting the dimensions of the communication passage 17 and the opening degree of the open / close valve 18,
The resonance effect works in two stages of the low speed region and the high speed region of the engine, and the resonance effect and the intake inertia effect appear in a total of four engine speed regions so that a high output torque can be obtained over a wider range. It is also possible to do so.

[0023]

As is apparent from the above description, according to the present invention, a pair of distribution chambers are provided between a pair of cylinder rows of a V-type multi-cylinder engine, and each combustion chamber and each distribution chamber of the cylinder row is provided. Since the and intake pipes are connected to each other, the long main intake pipe and the short bypass intake pipe can be easily arranged. Further, since the distribution chambers are made to communicate with each other by the communication passage having a large diameter, the intake inertia effect can be exerted in two different rotation regions of the engine. Moreover, since the longer main intake pipe can also be straight, the intake resistance can be suppressed to a low level, and the intake charge efficiency can be increased especially in the low speed range. Further, since the distribution chambers can be cut off and the distribution chambers are connected to the collecting chamber by independent resonance tubes, the resonance effect can be exerted. Therefore, the intake charge efficiency can be increased in at least three engine speed regions, and an engine with high output over a wide range can be obtained. Further, the space between the cylinder rows of the V-type multi-cylinder engine or the like is used to accommodate the distribution chamber, the intake pipe, and the like, so that the engine can be made compact.

[Brief description of drawings]

FIG. 1 shows an embodiment of an intake device according to the present invention, and is a front view of a V-shaped multi-cylinder engine main part with a cutout, the intake device being provided.

FIG. 2 is a schematic plan view of a main part of the intake device with a cutout.

FIG. 3 is a graph showing a torque characteristic curve of the engine.

[Explanation of symbols]

1 Engine Body 2 ₁ , 2 ₂ Cylinder Row 3 ₁ , 3 ₂ Cylinder 6 Combustion Chamber 9 Intake Valve 11 ₁ , 11 ₂ Distribution Chamber 12 ₁ , 12 ₂ Main Intake Pipe 13 ₁ , 13 ₂ Bypass Intake Pipe 15 Pipe Length Switching Valve 17 Communication passage 18 Open / close valve 20 ₁ , 20 ₂ Resonance tube 21 Collecting chamber

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[Procedure amendment]

[Submission date] November 17, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (1)

[Claims] 1. An intake system for a V-shaped multi-cylinder engine in which a pair of cylinder rows composed of a plurality of cylinders having different intake valve opening timings are arranged in a V shape. In addition, a pair of distribution chambers are juxtaposed substantially parallel to the longitudinal direction of the cylinder rows, and the distribution chambers and the combustion chambers of the cylinders belonging to the cylinder row on the side far from the distribution chambers are relatively long main intake air. And the combustion chambers of the cylinders belonging to the cylinder row on the side closer to the distribution chamber are connected via relatively short bypass intake pipes, respectively, and the main intake pipes and bypasses of the respective cylinders are connected. A pipe length switching valve for switching between the intake pipe and the intake pipe is provided, and the pair of distribution chambers can be blocked by a communication passage having an opening / closing valve, and the distribution chambers can be separated from each other. Is connected to the set chamber through an independent resonance tube, characterized in that is, the intake system of the V-shaped multi-cylinder engine.