JP2611798B2 - Engine intake system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake device for an engine that performs supercharging by utilizing natural vibration of an intake system.

(Prior Art) Conventionally, an intake device that uses a pressure fluctuation generated in an intake passage between cylinders of a multi-cylinder engine to increase a pressure in an intake port portion in the latter half of an intake stroke to obtain a supercharging effect has been proposed. Various proposals have been made. One of the dynamic effects of this intake is inertial supercharging. In the inertial supercharging, a negative pressure wave from a cylinder in an intake stroke is inverted to a positive pressure wave by an intake expansion section, and supercharging is performed by an intake pushing action by the positive pressure wave.

As another thing of this dynamic effect of intake, Japanese Patent Publication No. 60-141
As shown in JP 69, there is resonance supercharging. In this resonance supercharging, a plurality of cylinders are divided into a first cylinder group and a second cylinder group whose intake strokes are not adjacent to each other, and each cylinder of the first cylinder group is connected to a first collecting passage via a branch intake pipe. Communicated with
Each cylinder of the second cylinder group is connected to the second cylinder via a branch intake pipe.
It is communicated with the collective passage. The two collecting passages are connected to a common collecting part via independent resonance tubes. With this configuration, the air column in the resonance pipe is vibrated due to the pressure wave generated by the periodic opening and closing of the intake port, and the vibration in the resonance pipe causes the air in the first and second collecting passages and the air in the branch intake pipe to oscillate. It will vibrate. Then, when the resonance of the vibration occurs, the amplitude of the pressure vibration becomes maximum, and a large supercharging is performed.

When the intake air is supercharged using the above-described intake resonance phenomenon, the resonance frequency of the intake air is mainly determined according to the length (effective length) of the intake passage for resonance. Therefore, when the intake passage (pipe length) is determined, a tuning point is generated in a predetermined engine rotation range corresponding to the determined intake passage, and a torque peak point is generated. Various structures have been proposed in which a tuning point is set in a plurality of rotation ranges by using a plurality of resonance phenomena, and a passage length is changed in order to obtain a supercharging effect in a wide range. There is known a structure in which a communication path serving as a second pressure reversing part is provided downstream of a junction part serving as a part by opening and closing a valve.

Further, there has been proposed a structure of a loop-shaped intake passage in which an intake passage is formed in a loop shape by being communicated between an upstream side and a downstream side to change characteristics such as pressure wave propagation characteristics and intake distribution characteristics. .

(Problems to be Solved by the Invention) However, when the path length in the pressure propagation of the intake system is changed by opening and closing the valve of the communication path on the upstream side of the intake to change the natural vibration, When the length is shortened, there is a problem that the deviation of the natural vibration frequency with respect to each cylinder increases, and the peak point of the supercharging effect decreases.

In other words, when the passage length is relatively long, the ratio of the difference in passage length between the cylinders due to the difference in the connection position of each cylinder is small, and the difference in the natural vibration frequency in each cylinder is small, resulting in a favorable resonance state. The supercharging effect is increased, but when the passage length of the pressure propagation is shortened by opening the communication passage, the ratio of the difference in the passage length between the cylinders due to the difference in the connection position of each cylinder increases, and as a result, in each cylinder, , The resonance state is weakened, and the supercharging effect is reduced.

In addition, in an intake system in which a passage for each cylinder is sequentially connected to the intake passage, intake resistance is different between an upstream cylinder and a downstream cylinder, and intake distribution is not uniform, resulting in a torque imbalance between the cylinders. There is also a problem that occurs.

In view of the above circumstances, it is an object of the present invention to provide an intake system for an engine that can obtain a good supercharging effect even when a passage of an intake system having a loop-shaped intake passage is shortened. is there.

(Means for Solving the Problems) In order to achieve the above object, an intake device according to the present invention includes a first valve that shuts off a loop of a loop-shaped intake passage, and intake air that is supplied to each cylinder from a branch portion of an independent intake passage. A communication path for reducing the length of the loop by communicating an intermediate portion of the upstream loop-shaped intake path; and a second valve for opening and closing the communication path.
In the open region of the valve, the first valve is always controlled to be in the open state.

(Operation) In the above-described engine intake device, the second communication passage
When the valve is opened to shorten the passage length in the pressure propagation, the first valve that interrupts the loop is opened to form a loop-shaped intake passage, and the difference in the passage length from the communication passage to each cylinder is determined. By increasing the ratio and increasing the ratio of the shift of the natural vibration frequency, the pressure is propagated from upstream and downstream by forming a loop to improve the imbalance between cylinders, obtain a high resonance effect, and improve the distribution. I have to.

(Embodiments) Each embodiment of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 shows a schematic passage configuration of an intake device of a V-type six-cylinder engine.

The V-type engine body 1 includes a left bank 1L and a right bank 1R arranged so as to form a V-type with each other.
It has three cylinders 2a, 2c, 2e of No. 1, 3, 5 and the right bang 1R is 2,
It has three cylinders 2b, 2d and 2f of Nos. 4 and 6. The ignition order of the cylinders 2a to 2f is set, for example, in the order of 1-6-3--4-5-2 cylinders, and the ignition order is not adjacent in each of the banks 1L and 1R.

An intake passage 4 for supplying intake air to an intake port 3 opened to each of the cylinders 2a to 2f is provided with an air cleaner 5, an intake air amount sensor 6, and a throttle valve 7 from the upstream side. The upper branch portion 8 branches into a left resonance intake passage 11 for the left bank 1L and a right resonance intake passage 12 for the right bank 1R. The left resonance intake passage 11 is independently connected to the intake port 3 of each cylinder via the independent intake passages 13e, 13c, 13a from the upstream side in the order of the fifth, third, and first cylinders 2e, 2c, 2a of the left bank 1L. Have been. On the other hand, the right resonance intake passage 12 is independently connected to the intake port 3 of each cylinder by the independent intake passages 13f, 13d, 13b from the upstream side in the order of the sixth, fourth, and second cylinders 2f, 2d, 2b of the right bank 1R. Have been. The upstream branch portions 8 of the resonance intake passages 11 and 12 are pressure reversing portions for resonance.

The left and right resonance intake passages 11 and 12 are connected to the downstream cylinder 2
The downstream ends of the two resonance intake passages 11 and 12 are further extended from the branch portions of the independent intake passages 13a and 13b to a and 2b.

The upstream and downstream of the left and right resonance intake passages 11 and 12 are connected in a loop by the upstream branch portion 8 and the downstream connection passage 15 to form a loop-shaped intake passage 4A. First valves 16, 16 for interrupting the loop are interposed in the downstream connection path 15 at the downstream end of the left and right resonance intake paths 11, 12 of the loop-shaped intake path 4A.

Furthermore, the left and right resonance intake passages of the loop-shaped intake passage 4A
Independent intake passages 13a to 13f to cylinders 2a to 2f at 11, 12
A communication passage 1 that communicates left and right resonance intake passages 11 and 12 at an intermediate portion of the loop-shaped intake passage 4A on the upstream side of the branch portion and on the downstream side of the upstream branch portion 8 to shorten the loop length.
7 is connected. A second valve 18 that opens and closes the communication passage 17 is provided in the communication passage 17.

The opening and closing operations of the first valve 16 and the second valve 18 are as follows:
As shown in FIG. 2, the engine speed is set to a first set value A.
In the lower low speed range, both valves 16 and 18 are both closed,
When the first valve 16 exceeds the first set value A and fully exceeds the second set value B shifted by a predetermined value α, the second valve 18 is controlled to open. In the open region of the second valve 18, The control is performed so that the first valve 16 is always opened.

Explaining the operation of the present example, the first rotation in the low rotation state
In a state where both the valve 16 and the second valve 18 are closed, and the loops of the resonance intake passages 11 and 12 are shut off, the natural vibration having a long passage length due to the communication at the first pressure reversing section of the upstream branch section 9. The system achieves tuning in the low rotation range. That is, each cylinder
The pressure waves generated from 2a to 2f propagate through the respective resonance intake passages 11 and 12, and are reversed at the upstream branch portion 8 to increase the intake port pressure at the end of the intake stroke, thereby increasing the filling amount by the resonance supercharging effect.

In the middle rotation range, the first valve 16 is opened, and the second valve 16 is opened.
18 is closed, and the first valve 16 on the downstream side forms a loop-shaped intake passage 4A while the upstream side has a long passage length.
The communication of the downstream connection passage 15 acts as if the volume of pressure propagation in the left and right resonance intake passages 11 and 12 increased, and the natural frequency increased as well as the passage length became shorter, and the tuning rotational speed became higher. Attains tuning in the middle rotation range. In addition, the communication of the downstream connection passage 15 allows air downstream of the two resonance intake passages 11 and 12 to circulate with each other, thereby facilitating intake of the first and second cylinders 2a and 2b on the downstream side, thereby improving intake distribution. improves.

Before the first valve 16 is opened in the middle rotation range, the second
When the valve 18 is opened, the length of the pressure propagation path is shortened by the communication of the communication path 17 in a state where the downstream end is closed, and the left and right resonance intake paths 11, 12
The distance to the fifth cylinder 2e or the sixth cylinder 2f on the upstream side of
The ratio of the difference with the distance to the first cylinder 2a or the second cylinder 2b on the downstream side increases, and the tuning point of each of the cylinders 2a to 2f shifts to weaken the resonance effect, so that this state does not occur. I have to.

Further, the first valve 16 and the second valve 16
In the state where both of 18 are opened and the loop-shaped intake passage 4A is formed, the upstream sides of the two resonance intake passages 11 and 12 communicate with each other through the communication passage 17 to reduce the pressure propagation passage length, and further increase the natural frequency. Rise, the tuning speed increases, and tuning is obtained in the high speed range,
At each tuning point, a torque increase is obtained in a wide area by resonance supercharging.

FIG. 3 shows another example of the opening control of the first valve 16 and the second valve 18.

In this control example, when opening and closing the first valve 16 and the second valve 18, the opening is adjusted so that the opening gradually changes in response to a change in the engine speed. When the engine speed increases, after the first valve 16 is gradually opened from the point A to be in the fully open state, the predetermined value β
The second valve 18 is controlled so as to gradually open from the point B by shifting. With this control, the tuning point is continuously shifted so as not to cause a drop in torque from the tuning point in the low-speed range, and a smooth torque characteristic is obtained up to the high-speed rotation range.

FIG. 4 shows still another example of the opening control of the first valve 16 and the second valve 18.

In this control example, while the engine speed increases, the first valve 16 is gradually opened from the point A to be in a fully open state, and then the second valve 18 is opened to the fully open state at a point B and the first valve 16 is simultaneously opened. The control is such that the valve 16 is closed to a predetermined opening degree θ and then gradually opened. By this control, as in the case of FIG. 3, a smooth torque characteristic is obtained from the low-speed rotation range to the high-speed rotation range. In order to prevent the first valve 16 from being fully closed when the second valve 18 is opened, the first valve 16 is opened by the predetermined opening θ (for example, 3 ° or more) so as to obtain the communication state of the downstream connection path 15. is there.

Embodiment 2 FIG. 5 shows a schematic passage configuration of an intake device for an in-line four-cylinder engine according to this embodiment.

The engine body 20 has first to fourth cylinders 2a to 2d in series, and an intake passage for supplying intake air to an intake port 3 of each cylinder.
An air cleaner 5, an intake air sensor 6, and a throttle valve 7 are interposed from the upstream side. The downstream side of the throttle valve 7 branches from the upstream branch portion 8 into a main resonance intake passage 22 and an auxiliary resonance intake passage 23. Have been. And the main resonance intake passage 22
The first to fourth cylinders 2a to 2d are connected to the intake ports 3 of the cylinders 2a to 2d independently from the upstream side by independent intake passages 13a to 13d in order from the fourth cylinder 2d.

In addition, the two resonance intake passages 22 and 23 have their downstream ends communicated with each other by a downstream connection passage 25 to form a loop-shaped intake passage 21A.
Is formed, and a first valve 26 for interrupting the loop is interposed in the downstream connection path 25. Further, on the upstream side of the branch portion to the fourth cylinder 2d, a communication passage 27 that communicates the two resonance intake passages 22 and 23 to shorten the loop length of the loop-shaped intake passage 21A.
Is connected. A second valve 28 that opens and closes the communication passage 27 is provided in the communication passage 27.

The opening / closing control of the first valve 26 and the second valve 28 is performed in the same manner as in the previous example. When the first valve 26 is fully closed, the second valve 28 is controlled so as not to open, and the tuning in each of the cylinders 2a to 2d is performed. The frequency shift is reduced.

FIG. 6 shows a modification of the first valve.
This is a structural example in which the passage area of the downstream connection path can be changed in multiple stages.

The downstream connection path 30 is divided into a plurality of (three in the figure) passages 30a to 30c by partition walls 31a and 31b.
A first valve 32 is provided at the inlet of 0c. This first
In the valve 32, a valve body 32a having a fan-shaped cross section is installed so as to be rotatable.
To 30c are sequentially opened and closed, and the valve body 32a is operated by the motor 33 to a predetermined opening corresponding to the engine rotation speed. In the low-speed rotation region, the number of open passages is reduced, and the opening is made fully open when the rotation increases. In this structure, the attenuation of the pressure propagation when the passage area is reduced is small, and the resonance effect is enhanced.

FIG. 7 shows another structural example of the downstream connection path and the first valve, and the area of the connection path can be changed continuously.

The downstream connection path 35 is divided into a plurality (three) by partitions 36a and 36b, and a slide-type first valve 37 is interposed in the middle thereof. The first valve 37 is slid by an actuator 38 to open and close the connection path 35 in a plate-like valve body.
37a, and the valve body 37a has partitions 39a, 39 having different lengths.
The partitions 39a and 39b are provided so as to sequentially open and close the communication between the partition passages 35a to 35c by sliding contact with the partition walls 36a and 36b, and change the communication area (passage area).

In the low engine speed range, the valve body 37a is operated in a protruding state, and all the partition passages 35a to 35c are closed to interrupt the loop. Then, the valve body 37a is moved backward in response to an increase in the engine speed, and firstly communicates with the central section passage 35a to gradually increase the communication area. Then a short partition 39a
Opens the middle partition passage 35b away from the end of the partition 36a and gradually enlarges the communication area, and the longer partition 39b is
The outer partition passage 35c is opened apart from the end, and the communication area is gradually increased, so that the passage area is continuously changed as a whole, and the tuning point is changed continuously.

FIG. 8 shows still another example of the structure of the downstream connection passage and the first valve. The passage length at low speed is further changed by changing the passage area shown in FIG. Continuous change is possible.

The downstream connection path 35 is divided by partition walls 36a and 36b, and a slide-type first valve 37 'similar to the above is interposed. The first valve 37 'is provided with a plate-shaped valve body 37a which is slid by an actuator 38 and sequentially opens and closes the partition passages 35a to 35c by partitions 39a and 39b having different lengths. Further, a cylindrical sliding member 41 is provided on the outer periphery of the fixedly formed downstream connection passage 35, and a sliding wall 41a on the center side is integrally formed with the sliding member 41, and a valve body similar to that described above is provided. 37a
In addition to changing the passage area by opening and closing each of the partition passages 35a to 35c due to the movement of the valve member 35a, the sliding member 41 and the sliding wall 41a are moved together with the valve body 35a in a state where each of the partition passages 35a to 35c is closed and closed. The length of the passage is changed so that, at the lowest speed, the passage length of the resonance intake passages on both sides is maximized to lower the tuning point.

Then, the first valves 32, 37,
Also at 37 ', the communication passage 17 is provided by the second valve 18 (28).
When the opening operation of (27) is performed, the opening of the downstream connection paths 30 and 35 is opened by a predetermined amount, or the minimum opening degree is regulated or the communication of the minimum passage is ensured.

The downstream connection portion forming the loop-shaped intake passage in each of the above embodiments is formed in a loop shape by connecting to the resonance intake passage downstream of the branch portion of the independent intake passage to the most upstream cylinder. It is.

In the present invention, the second valve of the communication path is not opened while the loop is closed.
The tuning point in the state where the valve is closed and the second valve is open is substantially the same as the tuning point in the long loop passage where the first valve is open and the second valve is closed, and is higher than that. Since the resonance supercharging is obtained, no torque reduction occurs.

(Effects of the Invention) According to the present invention as described above, the first valve that shuts off the loop of the loop-shaped intake passage and the communication passage that communicates with an intermediate portion of the loop-shaped intake passage to shorten the loop length are opened and closed. And a second valve, which is always in the open region of the second valve.
When the second valve is opened to reduce the passage length in pressure propagation by controlling the valve to be in the open state, a loop-shaped intake passage is formed, and the passage length from the communication passage to each cylinder is controlled. By increasing the ratio of the difference of the height and the ratio of the deviation of the natural vibration, the pressure is transmitted from upstream and downstream by forming a loop to improve the imbalance between cylinders, obtain a high resonance effect, and distribute Can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an intake device of an engine according to a first embodiment of the present invention, FIG. 2 is a characteristic diagram showing opening and closing control of first and second valves of the engine, and FIG. FIG. 4 is a characteristic diagram showing another example of the opening / closing control of the valve, FIG. 4 is a characteristic diagram showing another example of the opening / closing control of the valve, FIG. 5 is a schematic configuration diagram of an engine intake device in the second embodiment, 6 is a sectional view showing a modification of the first valve, FIG. 7 is a sectional view showing another modification of the valve, and FIG. 8 is a sectional view showing still another modification of the valve. is there. 1,20 ... engine body, 2a-2f ... cylinder, 3 ... intake port, 4,21 ... intake passage, 4A, 21A ... loop-like intake passage, 8 ... upstream branch, 11,12, 22,23 ... Resonant intake passage, 13a to 13f ... Independent intake passage, 15,25,30,35 ... Downstream connection passage, 16,26,32,37,37 '... First valve, 17,27 ......
Communication passage, 18, 28 ... second valve.

Claims (1)

(57) [Claims] 1. An intake system for an engine having a loop-shaped intake passage, wherein a first valve for interrupting a loop of the loop-shaped intake passage, and a loop-shaped intake passage upstream of a branch of an independent intake passage to each cylinder. A communication path that communicates with a middle part of the intake passage to shorten the loop length and a second valve that opens and closes the communication path are provided, and the first valve is always opened in an open region of the second valve. An intake device for an engine, which is controlled.