JPH0823294B2 - Engine intake system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for an engine, and more particularly to an improved technique of a supercharging system for supercharging intake air to each cylinder of a multi-cylinder engine.

(Prior Art) Conventionally, there have been known various ones in which the filling efficiency is increased by a dynamic effect of intake air taken into a combustion chamber in a cylinder of an engine to increase the output torque of the engine. As an example thereof, in the one disclosed in Japanese Patent Publication No. 60-14169, etc., the intake passage in a multi-cylinder engine is connected to a cylinder group in which cylinders whose intake order (ignition order) is not continuous belong to the same group. The intake passage is divided into two intake passages, and each intake passage is composed of an expansion chamber to which the upstream end of the branch portion of the intake manifold is connected and a resonance passage connected to the expansion chamber, and the upstream end of the resonance passage. Is connected to the upstream side collecting chamber, and a switching device for switching both intake passages to a communication state or a communication cutoff state is provided in the expansion chamber, and when the communication between the intake passages is cut off by the switching device, The negative pressure wave generated in the intake stroke is reflected by the upstream side collecting chamber to be inverted to the positive pressure wave, and the inverted positive pressure wave causes the resonance supercharging effect of the intake in a relatively low rotation range. On the other hand, when the intake passages are communicated with each other, the reversal reflection position of the intake pressure wave is brought closer to the intake port to increase the natural frequency of the intake pressure vibration, and the resonance supercharging effect in the high speed rotation range. Is designed to get you.

Further, in what is disclosed in JP-A-56-52522,
A loop is formed in the intake manifold connected to the air cleaner to allow the intake air to flow in one direction in the loop, and the intake pipe branch-connected to the intake manifold has an intake flow in the loop with respect to the manifold. By installing so as to form an acute angle with the direction, the intake flow velocity in the loop is utilized, and the intake charging efficiency is increased by its inertial force.

(Problems to be Solved by the Invention) However, in the former one described above, since the large volume expansion chamber is provided at the gathering portion of the intake manifold branch portion, the intake system becomes large in size and a large installation space is required. There are problems such as costs.

Therefore, in the latter technique described above, attention is paid to the point that a loop portion is formed in the intake manifold, and for example, the intake ports of two cylinder groups in which the cylinders whose intake orders are not consecutive are in the same group are not shared by the expansion chambers. The annular intake passage for resonance is connected to the intake port of each cylinder of one cylinder group, and the portion that communicates with the intake port of each cylinder of the other cylinder group is in two directions. To form an annular shape that is connected to each other on both sides, and the length of the both-side communication path between the two cylinder groups is formed sufficiently larger than the length between the intake ports of the adjacent cylinders of the same cylinder group. , The positive pressure wave generated near the intake port at the end of the intake stroke of each cylinder of the cylinder group is made to travel around the resonance annular passage substantially once to act on the intake ports of other cylinders of the same cylinder group. of While effectively be exhibited an effect, it is conceivable to make compact the size and the required expansion chamber intake.

Furthermore, not only the intake supercharging effect of the annular intake passage but also the intake port of each cylinder is connected to an intake passage having no capacity expansion chamber such as a surge tank, and the resonance frequency of the intake air in the intake passage is connected. By setting the length of the intake passage so that the engine speed becomes a specific rotation range (for example, a low speed rotation range) of the engine, it is possible to supercharge the intake air by its resonance effect.

Then, in that case, the intake supercharging effect is increased by shortening the overlap period of the intake stroke between the cylinders in which the intake order is continuous. That is, since the magnitude of the negative pressure of intake air is a combination of pressure waves generated in the intake stroke of each cylinder, when the overlap period of intake air is large, the intake negative pressure during the overlap period is added. Even if there is resonance supercharging of intake air, the pressure wave cancels out with the negative pressure, and the supercharging effect decreases.

By the way, a cam for driving the intake / exhaust valve of the engine to open and close is a low speed cam having a cam profile with a narrow valve opening angle,
Consists of a high-speed cam with a cam profile that has a wide valve opening and a large lift amount.In the low engine speed range, the low-speed cam opens and closes the intake valve to cut the intake charge and improve fuel efficiency. On the other hand, in the high speed rotation range, a variable intake timing mechanism is known in which the intake valve is opened and closed by the high speed cam to improve the output torque of the engine.

When the above-described intake device is applied to the engine having the variable intake timing mechanism, the variable intake timing mechanism shortens the overlap period of the intake stroke of each cylinder due to the narrow valve opening angle in the low speed rotation range of the engine. Therefore, an effective resonance supercharging effect can be obtained.
However, on the other hand, in the high-speed rotation range, the valve opening angle of the cam increases, so that the overlap period of the intake stroke becomes longer, and it becomes difficult to obtain a good supercharging effect as described above. .

The present invention has been made in view of the above points, and an object thereof is to reduce intake air from resonance supercharging instead of resonance supercharging when the valve opening angle is widened in the high speed rotation range of the engine by the intake timing variable mechanism or the like. By performing supercharging with an appropriate supercharging method, it is possible to reliably supercharge the intake air even if the overlap period of the intake stroke between the cylinders changes, and thus, it is possible to supercharge over a wide engine speed range. The purpose of this is to make good the effect of supply, increase the amount of intake air charged, and increase its output torque.

(Means for Solving the Problems) In order to achieve this object, the solution means of the present invention uses an intake timing variable mechanism to shorten the overlap period of the intake stroke between the cylinders in the low speed rotation range of the engine. In this case, the intake air is supercharged by resonance supercharging. On the other hand, when the intake overlap period becomes long in the high speed rotation range, a volume expansion portion is formed in the intake system so that the intake air is supercharged by inertial supercharging. That is, the supercharging system is changed according to the presence or absence of a volume expansion part in the middle of the intake system, and in the low speed rotation range where the overlap period is shortened, the volume of the intake system is reduced to perform resonance supercharging, and high speed rotation is performed. In the region, a volume expansion portion is formed in the intake system in order to perform inertia supercharging, and the inertia supercharging effect between the volume expansion portion and each intake valve is emphasized.

Specifically, the configuration of the present invention includes an intake timing variable mechanism that changes the substantial overlap period of the intake stroke of each cylinder in a multi-cylinder engine, and an intake volume variable mechanism that forms a volume expansion part in the intake system. It is basically equipped with.

Furthermore, in the low engine speed region, the volume expansion part is not formed in the intake system to cause resonance supercharging of the intake system, and the overlap period of the intake stroke of each cylinder is reduced, while in the high engine speed region, Control means for controlling the intake timing variable mechanism and the intake volume variable mechanism so as to form a volume expansion part in the intake system so as to cause the inertia supercharging and to increase the overlap period of the intake stroke of each cylinder. Set up.

(Operation) With this configuration, when the engine is in the low speed rotation range,
The intake timing variable mechanism is controlled by the control means,
The substantial overlap period of the intake stroke of each cylinder is adjusted to be short. Further, the intake volume variable mechanism is also controlled in association with the shortening of the overlap period of the intake stroke, so that the volume expansion section serving as the reflection section of the intake pressure wave is not formed in the intake system of the engine. As a result, resonance supercharging of intake air is generated in the intake system, and the intake supercharging amount in the low speed rotation range can be increased by this resonance supercharging effect.

On the other hand, when the engine shifts to the high speed rotation range, the substantial overlap period of the intake stroke of each cylinder is adjusted to be long. Then, the intake volume varying mechanism is also controlled in association with this adjustment, and a volume expansion section is formed in the intake system of the engine. The volume expanding section increases the inertia supercharging effect of intake air between the volume expanding section and the intake valve, and the increase of the inertia supercharging effect makes it possible to increase the intake charge amount in the high speed rotation range. Therefore, the intake charge amount can be increased over a wide rotation range of the engine from the low speed rotation range to the high speed rotation range.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 shows the overall construction of the first embodiment of the present invention, where 1 is a DO having four cylinders 2a to 2d arranged in series.
HC type in-line 4-cylinder engine, which has the above-mentioned four cylinders 2a to
The ignition order of 2d is as follows: first cylinder 2a, third cylinder 2c, fourth cylinder 2d,
The second cylinder 2b is set in order. For each cylinder 2a-2d,
Two intake ports 4, 4 each opened and closed by the intake valve 3
And one exhaust port 6 opened and closed by the exhaust valve 5 ,. Reference numeral 7 denotes an intake passage for supplying intake air into each of the cylinders 2a to 2d, and the intake passage 7 includes a resonance intake passage 8
Formed by the collecting pipe portion 12 of the intake manifold 11,
A collective intake passage 9 continuous to the downstream end of the resonance passage 8;
The intake manifold 11 includes four independent intake passages 10a to 10d formed in the branch pipe portions 13a to 13d and branched in parallel from the collective intake passage 9 to form the independent intake passages 10 described above.
The downstream side portions of a to 10d are branched into two forks, and the downstream ends thereof are the two intake ports of the cylinders 2a to 2d, respectively.
Connected to 4,4. Further, the upstream end of the resonance intake passage 8 is connected to an air cleaner 14, and intake air (air) sucked from the air cleaner 14 is supplied to the resonance intake passage 8, the collective intake passage 9 and each independent intake passage 10a.
It is designed to supply each cylinder 2a to 2d through ~ 10d. An air flow meter 15 for measuring the amount of intake air is arranged in the intake passage 7 immediately downstream of the air cleaner 14, and an upstream collecting chamber 16 having a larger volume than other parts is formed on the downstream side of the air flow meter 15. There is. The equivalent length of the intake passage 7 between the intake ports 4, 4 of each of the cylinders 2a to 2d and the collecting chamber 16 is approximately equal to the resonance pressure due to the reciprocal propagation of the pressure wave of the intake in the low speed rotation range of the engine 1. It is set to the natural frequency at which feeding is performed.

Further, the intake passage 7 in the collecting pipe portion 12 of the intake manifold 11 is communicated with the expansion chamber 18 having a relatively large volume through the communication passage 17, and the communication passage 17 is opened and closed by the communication passage 17. An on-off valve 19 for switching the intake passage 7 in the collecting pipe portion 12 and the expansion chamber 18 to a communication state or a closed state thereof is provided.
Then, the volume of the intake system is variably controlled by opening / closing the open / close valve 19, and when the open / close valve 19 is closed, the volume of the intake system is reduced by eliminating the volume expansion part in the middle of the intake system, while the open / close valve 19 is opened. In this case, the intake volume variable mechanism 20 is configured so as to increase the volume of the intake system by forming a volume expansion part by the expansion chamber 18 in the middle of the intake system.

The two intake valves 3, 3 of each of the cylinders 2a to 2d are the intake valve operating mechanism 2
Driven by 1. As shown in FIG. 2, the intake valve operating mechanism 21 includes one intake camshaft 22 for driving an intake valve.
And two low-speed rocker arms 25, 25 and one high-speed rocker arm 27, and the intake camshaft 22
A pair of low speed cams 23, 23 and a high speed cam 24 disposed between the low speed cams 23, 23 are formed on the upper side, and each of the low speed cams 23 has a cam profile with a narrow valve opening angle. , High speed cam 24
Is set to a cam profile having a wider valve opening angle and a larger cam lift than the low speed cam 23.

Further, each low-speed rocker arm 25 is swingably supported with a pivot 26 at one end (upper end in FIG. 2) as a fulcrum,
The other end lower surface is in contact with each intake valve 3 and the intermediate upper surface is in contact with each low speed cam 23 on the intake camshaft 22. The high speed rocker arm 27 is arranged between the low speed rocker arms 25 and 25. The high-speed rocker arm 27 is swingably supported by a pivot 28 at one end (upper end in the figure) as a fulcrum, and the upper surface of the other end is in contact with the high-speed cam 24. The high-speed rocker arm 27 has an oil passage 29 formed therein, which communicates with the pivot 28, and the upstream end of the oil passage 29 has an oil discharge pressure which increases according to the engine speed, although not shown. The changing oil pump is communicated with the oil passage through the oil passage in the cylinder head of the engine 1, and the oil from the oil pump is sent to the oil passage 29.

Each of the rocker arms 25, 27 has a cylindrical hollow portion 25a, which communicates with a position directly below the center of rotation of the camshaft 22.
27a are formed respectively, and an engagement mechanism 30 for engaging the low speed rocker arm 25 and the high speed rocker arm 27 in a swinging integrated manner is disposed in each of the hollow portions 25a, 27a. This engagement mechanism
Reference numeral 30 denotes a return pin 32 that is inserted into the hollow portion 25a of each low-speed rocker arm 25 and is urged by a spring 31 toward the high-speed rocker arm 27, and a camshaft inside the hollow portion 27a of the high-speed rocker arm 27. An engaging pin 33 that is slidably inserted in 22 directions and that engages each low-speed rocker arm 25 with the high-speed rocker arm 27 in a swinging manner by moving and fitting the low-speed rocker arm 25 into the hollow portion 25a. Composed of. The downstream end of the oil passage 29 is opened in the center of the hollow portion 27a of the high-speed rocker arm 27.
In the low speed rotation range of the engine 1 where the discharge pressure of the oil pump is low, the engagement pin 33 is housed in the hollow portion 27a of the high speed rocker arm 27 by the return pin 32, and the low speed rocker arm 25 and the high speed rocker arm 27 are placed. The low-speed cam 23 and the high-speed cam 24 of the intake camshaft 22 are brought into contact with each other to swing with different lift amounts, while in the high-speed rotation range of the engine 1, high-pressure oil discharged from the oil pump is used. Through the oil passage 29 through the hollow part
27a, and the pressure of the oil flowing into the hollow portion 27a presses the engagement pin 33 against the biasing force of the return pin 32 to push it into the hollow portion 25a of each low-speed rocker arm 25. Low-speed rocker arm 25 and high-speed rocker arm
27 and 27 are integrally engaged. Therefore,
As shown in FIG. 3, in the low speed rotation range of the engine 1, by separating the low speed rocker arm 25 and the high speed rocker arm 27, each intake valve 3 is driven to open and close by the low speed cam 23. As shown in, the intake valve 3 of each cylinder 2a to 2d is narrowed in opening angle, while in the high-speed rotation region, the two types of rocker arms 25 and 27 are integrally engaged so that each intake valve 3
Is opened and closed by the high-speed cam 24 that is dominant in the cam profile, so that the opening angle of each intake valve 3 is expanded as shown by the broken line in the figure, and the actual intake stroke of each cylinder 2a to 2d is The intake timing variable mechanism 34 is configured to change the typical overlap period between the low speed region and the high speed region of the engine 1.

Further, the opening / closing valve 19 of the variable volume mechanism 20 is configured to be operated and controlled by the control unit 35. An output signal of a rotation sensor 36 for detecting the rotation speed of the engine 1 is input to the control unit 35, and the intake volume variable mechanism 20 is controlled by the control unit 35.
In addition, the intake timing variable mechanism 34 is controlled by an oil pump in accordance with the rotation range of the engine 1, and in the low speed rotation range of the engine 1, the on-off valve 19 is closed to cause resonance supercharging of intake air. While the volume expansion part by the expansion chamber 18 is not formed, and the intake timing variable mechanism 34 is set to the operating state of the low speed cam 23, the overlap period of the intake stroke of each cylinder 2a to 2d is reduced, while in the high speed rotation range. In order to cause inertial supercharging of the intake air, the on-off valve 19 is opened to form a volume expansion part by the expansion chamber 18 in the intake system, and the intake timing variable mechanism 34 is set to the operating state of the high-speed cam 24 to set each cylinder 2a. It is configured to make the overlap period of the intake stroke of ~ 2d large.

Therefore, in the above embodiment, the operation of the intake timing variable mechanism 34 and the opening / closing valve 19 of the volume variable mechanism 20 is controlled based on the engine speed detected by the rotation sensor 36. When the engine 1 is in the low speed rotation range, the low speed cam 23 of the intake timing variable mechanism 34 is used, and the intake timing is controlled so that the intake overlap period between the cylinders 2a to 2d is shortened. At the same time, the on-off valve 19 of the variable volume mechanism 20 is closed, and the intake passage 7 in the collecting pipe portion 12 of the intake manifold 11 is closed.
The communication between the expansion chamber 18 and the expansion chamber 18 is blocked, and a large volume expansion part is not formed in the intake passage 7. Therefore, the negative pressure wave generated at the end of each intake stroke is propagated to the upstream side through the collective intake passage 9 in the collecting pipe portion 12 or the resonance intake passage 8 upstream thereof, and the upstream end of the resonance intake passage 8 Is reflected in the collecting chamber 16 and is inverted to a positive pressure wave, and the positive pressure wave is propagated to the downstream side and overlaps the intake stroke with the cylinders 2a to 2d and acts on the initial intake stroke of the next cylinder 2a to 2d. However, this positive pressure wave increases the intake charge amount into the cylinders 2a to 2d. The above behavior is repeated for each cylinder 2a to 2d.

At that time, since the overlap period between the intake strokes of the cylinders 2a to 2d is shortened by the intake timing variable mechanism 34, the magnitude of the combined value of the negative pressures generated in the intake strokes of the cylinders 2a to 2d. Becomes smaller, and as a result, an effective resonance supercharging effect can be obtained, the intake charging efficiency can be increased, and the output torque of the engine 1 can be increased.

On the other hand, when the engine 1 is in the high speed rotation range, the high speed cam 24 of the intake timing varying mechanism 34 is used, and the intake timing is controlled so that the intake overlap period between the cylinders 2a to 2d becomes longer depending on the cam timing. Therefore, the above-mentioned effective resonance supercharging effect cannot be obtained. However, in the high speed rotation range of the engine 1, the intake volume variable mechanism 20
The on-off valve 19 is opened, the collective intake passage 9 and the expansion chamber 18 are communicated with each other, and a large volume expansion portion is formed in the middle of the intake passage 7. Therefore, the negative pressure wave generated at the beginning of each intake stroke is inverted and reflected by the expansion chamber 18 communicating with the collective intake passage 9 to become a positive pressure wave, which acts at the end of the intake stroke of the same cylinder 2a to 2d. The effect of inertial supercharging of intake air between the expansion chamber 18 and the intake valve 3 is enhanced. As a result, the intake charging efficiency can be increased and the output torque of the engine 1 can be increased. Therefore, as shown in FIG. 4, the output torque of the engine 1 can be increased over a wide rotation range from the low speed rotation range to the high speed rotation range.

FIG. 5 shows a second embodiment (note that the same parts as those in FIG. 1 are designated by the same reference numerals and detailed description thereof is omitted), and the volume of the intake system is changed by changing the volume of the surge tank. I have to.

That is, in this embodiment, the engine 1'includes one intake port 4 for each cylinder 2'a-2'd. In addition, a surge tank 37 that forms the intake passage 7 is provided,
The intake passage 7 in the surge tank 37 has cylinders 2'a to
Independent intake passages in branch intake pipes 38a to 38d, respectively, at 2'd
It is communicated through 10a to 10d. Above surge tank 37
An enlarged portion 37b formed by partially enlarging a part thereof is formed on the. A partition plate 39 for partitioning the enlarged portion 37b from the tank body 37a is arranged in the enlarged portion 37b, and the partition plate 39 is movably supported in a range from the bottom of the enlarged portion 37b to the boundary with the tank body 37a. ing. The partition plate 39 is drive-connected via a connecting rod 41 to a drive motor 40 outside the surge tank 37 whose operation is controlled by the control unit 35. And a drive motor depending on the rotation range of the engine 1 '.
By driving the partition plate 39 by driving 40, and in the low speed rotation range of the engine 1 ′, by moving the partition plate 39 downward in the figure and positioning it near the boundary between the main body 37a and the enlarged portion 37b of the surge tank 37, While not forming a volume expansion part in the intake system,
In the high-speed rotation range, the partition plate 39 is moved upward in the figure and positioned at the bottom of the expansion part 37b, thereby forming a volume expansion part including the surge tank expansion part 37b in the intake system. Mechanism 20 'is constructed. The intake timing variable mechanism 34 has substantially the same structure as that of the first embodiment.

Therefore, in this embodiment, in the low speed rotation range of the engine 1 ', the intake timing variable mechanism 34 is controlled and the intake stroke overlap period between the cylinders 2'a to 2'd is adjusted to be short. Further, the partition plate 39 is positioned near the boundary between the main body 37a and the enlarged portion 37b of the surge tank 37 by the operation control of the drive motor 40 by the control unit 35, and the volume enlarged portion is not formed in the intake system. Therefore, the effective resonance supercharging effect of the intake air is exhibited.

On the other hand, in the high speed rotation range of the engine 1 ', the intake stroke overlap period between the cylinders 2'a to 2'd is adjusted to be long by the control of the intake timing variable mechanism 34. At the same time, the partition plate 39 is positioned at the bottom of the surge tank expansion portion 37b, and a volume expansion portion including the expansion portion 37b is formed in the intake system. Therefore, the effective resonance supercharging effect of the intake air cannot be obtained, but the inertia supercharging effect of the intake air can be increased, so that the same effect as the first embodiment can be obtained.

6 and 7 show the third embodiment, in which both the volume variable mechanism and the intake timing variable mechanism are changed.

In this embodiment, each cylinder 2'a to 2'd is provided in the intake passage 7.
A rotary valve 42 that substantially regulates the intake stroke of the is installed. The rotary valve 42 includes a cylindrical valve case 43 and a cylindrical valve body 46 that is rotatably and airtightly supported in the valve case 43. The one-end opening 44 of the valve case 43 is resonant. The air cleaner 14 communicates with the intake passage 8 (intake passage 7). Also,
Four openings 45a to 45d are formed on the outer circumference of the valve case 43, and each of the openings 45a to 45d is provided with a branch intake pipe 38'a.
Each cylinder 2'through independent intake passages 10a to 10d in
It is connected to the intake ports 4 of a to 2'd. On the other hand, at one end of the valve body 46, one end opening 44 of the valve case 43 is formed.
Is formed with an opening 47 that is in constant communication with. Further, on the outer circumference of the valve body 46, there are four openings 48a to 4a which can respectively match the corresponding outer circumference openings 45a to 45d of the valve case 43.
8d are formed at equal angular intervals in the circumferential direction, and when the rotation of the valve body 46 causes each of the openings 48a to 48d to match the corresponding openings 45a to 45d of the valve case 43, the rotary valve 42 is formed. To open the cylinder to intake air from the cylinder 2'a.
It is designed to be supplied in 2'd.

The valve body 46 is drivingly connected to the engine 1'through a valve control mechanism 49. The valve control mechanism 49 includes a driving screw member 50 having a one-way screw (for example, a right-hand screw) and a driven screw member having a screw of the other direction (for example, a left-hand screw), which is arranged to face each other on the same axis as the driving screw member 50.
51, and an operating member 52 that is screwed and supported by both the drive and driven screw members 50, 51 to rotate, and a driven sprocket 53 is connected to the drive screw member 50 so as to rotate integrally.
A chain 55 is wound between the driven sprocket 53 and the drive sprocket 54 connected to the output shaft 1'a of the engine 1 '. Further, the driven screw member 51 includes a rotary shaft 56 that supports the other end of the valve body 46 of the rotary valve 42.
Is integrally connected to. Further, the operating member 52
Is moved in the axial direction (rotation center direction) by an actuator 57 composed of a motor or the like controlled by the control unit 35 '. And
By driving the actuator 57, the operating member 52 is moved, and the driving and driven screw members 50, 51 screwed to the operating member 52 by reverse screws are rotated relative to each other during rotation. By changing the opening and closing timing of the engine, as shown in FIG.
In the low speed rotation range, the opening timing of the rotary valve 42 is advanced, and the opening angle of the intake valve 3 of each cylinder 2'a to 2'd is substantially reduced to shorten the intake overlap period. ,
In the high speed rotation range, the opening timing of the rotary valve 42 is delayed, and the valve opening angle of the intake valve 2 of each cylinder 2'a to 2'd is made larger than the original valve opening angle to lengthen the intake overlap period. The intake timing variable mechanism 34 'is configured as described above.

Further, 58 is a closed cylindrical communication pipe which is disposed and supported so as to intersect with the above four branch intake pipes 38'a to 38'd,
Inside the communication pipe 58, a communication passage 59 is formed which connects the independent intake passages 10a to 10d inside the branch intake pipes 38'a to 38'd to each other. Further, the communication passage 59 inside the communication pipe 58
And the intake passages 10a to 10d inside the respective branch intake pipes 38'a to 38'd
On / off valves 60, 60, ... Drive-connected to an actuator 60a which is controlled by the control unit 35 'are arranged at the connection portion with the respective open / close valves 60. The variable volume mechanism 20 ″ is configured so as to form a volume expansion part by the communication passage 59 in the intake system by opening at.

Therefore, in this embodiment, when the engine 1'is in the low speed rotation range, the opening timing of the rotary valve 42 is advanced by the intake timing variable mechanism 34 ',
While the intake overlap period is adjusted to be short, each on-off valve 60 of the variable volume mechanism 20 ″ is closed, and the volume expansion part due to the communication passage 59 is not formed in the intake system. The salary effect can be obtained.

On the other hand, when the engine 1'is in the high speed rotation range,
The opening timing of the rotary valve 42 is delayed by the intake timing variable mechanism 34 ', and the intake overlap period is adjusted to be long, and at the same time, the volume variable mechanism 20''is used.
The respective on-off valves 60 are simultaneously opened, and a volume expansion part is formed by the communication passage 59 in the intake system. Therefore, an effective inertia supercharging effect of intake air can be obtained. Therefore, engine 1 '
The output torque can be increased over a wide rotation range.

In the above embodiment, the case where the present invention is applied to the four-cylinder engine 1, 1'is shown, but it is needless to say that the present invention can be applied to a multi-cylinder engine other than the four-cylinder engine of the present invention.

(Effects of the Invention) As described above, according to the present invention, in the low-speed rotation range of a multi-cylinder engine, the intake volume variable mechanism eliminates the volume expansion part in the intake system to cause resonance supercharging of the intake air. The variable timing mechanism reduces the substantial overlap period of the intake stroke of each cylinder, while in the high speed region, the volume expansion part is formed in the intake system to increase the inertial supercharging of intake air and By making the overlap period of the stroke large, effective resonance supercharging is exhibited in the low speed region, while inertia supercharging effect can be coordinated in the high speed region, so that from the low speed region of the engine The output torque can be improved by increasing the intake charge amount over a wide rotation range up to the high-speed rotation range.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a configuration diagram showing the overall configuration of the first embodiment, FIG. 2 is a sectional view showing an intake timing variable mechanism, and FIG. 3 is an opening / closing of an intake valve of each cylinder. FIG. 4 is a timing chart showing the timing, and FIG. 4 is a characteristic diagram showing output torque change characteristics with respect to changes in the engine speed. FIG. 5 is a view corresponding to FIG. 1 showing the second embodiment. FIG. 6 is a view corresponding to FIG. 1 showing a third embodiment, FIG. 7 is a sectional view taken along the line VII-VII of FIG. 6, and FIG. 8 is a characteristic showing the opening / closing timing characteristic of the rotary valve with respect to the opening / closing timing of the intake valve. It is a figure. 1,1 '... Engine, 2a-2d, 2'a-2'd ... Cylinder, 1
8 …… Expansion chamber, 19 …… Open / close valve, 20,20 ′, 20 ″ …… Volume change mechanism, 34,34 ′ …… Intake timing change mechanism, 35,35 ′
...... Control unit, 37 ...... Surge tank, 37b
...... Expansion part, 42 ...... Rotary valve, 49 ...... Valve control mechanism, 58 ...... Communication part, 60 ...... Open / close valve.

Claims (1)

[Claims] 1. A multi-cylinder engine comprising an intake timing variable mechanism for changing a substantial overlap period of intake strokes of respective cylinders, and an intake volume variable mechanism for forming a volume expansion part in an intake system. In the low speed rotation range, the volume expansion part is not formed in the intake system to cause resonance supercharging of intake air, and the overlap period of the intake stroke of each cylinder is reduced, while in the high speed rotation range, the inertial supercharging of intake air is performed. And a control means for controlling the intake timing variable mechanism and the intake volume variable mechanism so as to increase the overlap period of the intake stroke of each cylinder. Characteristic engine intake device.