JPS5979038A - Intake apparatus for engine - Google Patents

Abstract

PURPOSE:To raise the charging efficiency of an engine over a wide range of engine operation from its medium-speed operation to high-speed operation, by utilizing the effect of interference between cylinders that is caused by a high- load intake system at the time of high speed operation of the engine and the effect of interference beween cylinders that is caused by a low-load intake system at the time of low-speed operation of the engine. CONSTITUTION:Compression wave produced near a high-load intake port 14 when a high-load intake valve 20 of a second cylinder 1B is opened is transmitted to a high-load intake port 14 of a first cylinder 1A at the end of suction stroke via a second high-load intake passage 10b, a connecting passage 16 and a first high-load intake passage 10a. On the other hand, compression wave produced near a low-load intake port 13 of an intake passage 9b when a low-load intake valve of the second cylinder 1B is opened is transmitted to a low-load intake port 13 of the first cylinder 1A at the end of suction stroke via the second low-load intake passage 9b, a connecting passage 18 and a first low-load intake passage 9a.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine intake system, and in particular to a multi-cylinder engine equipped with two independent intake passages, one for low load and one for high load. This invention relates to an engine that utilizes this to obtain a supercharging effect from the medium rotation range to the high rotation range of the engine.

Generally, a multi-cylinder engine includes an intake passage having two systems, a low-load intake passage and a high-load intake passage, which open independently to each cylinder, and the intake passage has at least a low-load intake passage. A primary valve that changes the amount of intake air,
It has a secondary valve that changes the amount of intake air flowing through the high-load intake passage, and when the engine is under low load, only the above-mentioned primary valve opens and intake air is taken only from the low-load intake passage with a narrow passage area. By supplying air to each cylinder, the intake flow rate is increased and combustion stability is improved. At the same time, when the engine is under high load, the above-mentioned secondary valve is also pre-intercropped to supply intake air from the high-load intake passage as well. By doing so, we were able to increase filling efficiency and improve output. So-called dual induction air intake systems are well known.

By the way, conventionally, the engine's charging efficiency has been improved.
In order to achieve this, the technology of supercharging the intake air by installing a supercharger in the intake passage is known (although it is known, the structure is complicated and the cost increases due to the supercharger being installed). .

In addition, as a technology to obtain a supercharging effect by the intake pressure waves generated in the intake passage of the engine,
As disclosed in Publication No. 21, in a single-cylinder engine, the intake pipe is divided into two passages with different dimensions, each having a separate intake port, and when the engine rotates at high speeds, the intake pipe is divided into two passages with different dimensions. At low engine speeds, the intake passage with the later closing position is closed and the intake air is blocked early, thereby blocking the intake air at the point of maximum intake pressure, which is a function of the intake pipe dimensions and engine speed. It has been proposed to obtain suitable charging efficiency over a wide range of engine speeds by utilizing the supercharging effect of .

However, this one is 1. It was designed for a single-cylinder engine, and its structure and operation were unclear, such as how to utilize the intake pressure waves generated in the intake passage, and it was difficult to immediately put it into practical use.

Therefore, when examining the intake characteristics of the engine, the inventors found that: (1) When the intake port is opened, the residual exhaust gas in the combustion chamber is compressed by the pressure of gas, and a compression wave is generated at the intake port part in the intake passage. This compression wave at the time of opening is particularly strong in recent commercial vehicles due to the increased engine exhaust pressure to reduce rustling noise and purify exhaust gas (
11) It was found that when the intake port is closed, the intake air is compressed due to the inertia of the intake air, and a compression wave is generated at the intake port portion in the intake passage.

Therefore, in a multi-cylinder engine equipped with two independent intake passages as described above, the present invention is capable of converting the compression wave of the above (1) when opening in one cylinder to other cylinders, in particular, causing intake air to blow back. A supercharging effect can be effectively obtained if it is applied at the end of the intake stroke (hereinafter referred to as the exhaust interference effect).
, and that a supercharging effect can be effectively obtained by applying the closing compression wave of (11) above in one cylinder to the same period (from the intake to the end of the air stroke) in the young cylinder (hereinafter referred to as the intake inertia effect). The aim is to improve the engine filling efficiency by focusing on this inter-cylinder interference effect (exhaust interference effect and intake inertia effect).

That is, an object of the present invention is to improve the intake system of a multi-cylinder engine having two intake passages as described above, in one of the low-load and high-load intake systems in a high engine rotation range.
On the other hand, in the lower rotation range, respectively'' - as shown (
Settings are made so that the pressure waves generated at the opening of one cylinder (compression wave when opening, compression wave when opening) are effectively propagated to other cylinders at the end of the intake stroke to effectively obtain a supercharging effect. This makes it possible to effectively improve output by increasing charging efficiency from the mid- to high-speed range of the engine, without using a supercharger, etc. (with a simple configuration by making slight design changes to the existing intake system). It is intended to be

In order to achieve this object, the configuration of the present invention includes an intake passage having a low-load intake passage and a high-load intake passage that open independently to each cylinder, and the intake passage has a low-load intake passage and a high-load intake passage. a primary valve that changes the amount of intake air flowing through the intake passage;
An intake system for an engine having a secondary valve that changes the amount of intake air flowing through a high-load intake passage, the engine having a secondary valve that changes the amount of intake air flowing through a high-load intake passage, and downstream of the primary valve and the secondary valve, the low-load intake passage of each cylinder and the high-load intake passage. The intake passages are connected to each other by a communication passage having a passage area larger than the minimum passage area of each intake passage, and the passage length of the low-load intake passage and the high-load intake passage between each cylinder via the communication passage. , either one is 5000~
When the engine rotates at a high speed of 7000 rpm, the pressure wave generated at the opening of one cylinder propagates to the other cylinder at the end of the intake stroke, supercharging it, and the other cylinder
1000 more than the reference rotation speed set between rpm
It is set so that the pressure wave generated at the opening of one cylinder at the low speed side of ~2000 rpm propagates to the other cylinder at the end of the intake stroke to perform supercharging. The inter-cylinder interference effect in the high-speed range, and the inter-cylinder interference effect in the lower-speed range, effectively increases the charging efficiency from the mid-speed range to the high-speed range of the engine. It is.

Here, the limitation of 5000 to 7000 rpm as the engine high speed to obtain the above-mentioned inter-cylinder interference effect is generally set within this range of maximum output and maximum speed. This is because it requires high output and is an effective area for improving filling efficiency and output.

In addition, the reason for making the low-load intake passage and the high-load intake passage independent in the downstream of the primary valve and the secondary valve is as follows.
This is to prevent the pressure waves generated in the low-load and high-load intake passages of each cylinder from dispersing to the other, or from interfering and weakening each other. This is because the opening/closing timing and length of the intake port are different from those of the intake passage due to differences in requirements in the dual induction intake system, and the pressure waves of one are reduced by the other.

In addition, the downstream position of the primary valve or secondary valve in each of the communication passages is set to avoid the presence of the primary valve and secondary valve, which acts as resistance to the propagation of pressure waves, and to attenuate the pressure waves. This is to reduce the size of the signal and propagate it effectively.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIGS. 1 and 2 show a first embodiment as a basic structural example in which the present invention is applied to a dual induction type four-valve two-cylinder four-stroke engine. In the figure, 1A and IE4; 1 are the first cylinder and the second cylinder, and 2 is a combustion chamber formed by the cylinder 3 and piston 4 in each cylinder 1A and 1B.

Reference numeral 5 denotes a main intake passage whose one end opens to the atmosphere via an air cleaner 6 and supplies intake air to each cylinder IA and IB. The main intake passage 5 is partitioned downstream of the air flow meter 7 by a partition wall 8 into a main low-load intake passage 9 and a main high-load intake passage 10. At 9, intercrop according to the increase in engine load! When the IuJ L predetermined load or more reaches 2, it is fully opened and the engine with low load is lowered.
1 Kukata 11 for changing the amount of intake air flowing through the cargo intake passage 9
is disposed in the main high-load intake passage 10, and the main high-load intake passage 10 is opened when the engine load exceeds a predetermined load to change the amount of intake air flowing through the main high-load intake passage 10 when the engine load is high. A secondary valve is provided. Furthermore, the main low-load intake passage 9 is branched into first and second low-load intake passages 9a and 9b having the same shape and dimensions at the downstream side 11, and then connected to low-load intake ports 13 and 13, respectively. The main high-load intake passage 10 communicates with the combustion chambers 2.2 of each cylinder IA and IB through the main high-load intake passage 10. iQa
, iob, and then each high-load intake port 14
It communicates with the combustion chambers 2, 2 of each cylinder IA, IB via 14. Therefore, for each cylinder IA, IB, low load intake passages 9a, 9b and high load intake passages 10a, 1
0b is configured to independently open into the combustion chamber 2 downstream of the first direction 11 and the second direction 12.

The minimum passage surface IJi As of each high-load intake passage 10a and iob is set to be thicker than the minimum passage area Ap of each low-load intake passage 9a and 9b (As>Ap).
, and the passage length l of each high-load intake passage 10a, 10b.
! S is the passage length I of each low-load intake passage 9a, 9b!
It is set shorter than P! 1l (I!S<ep),
In particular, the propagation of pressure waves through the high-load intake passages 10a and 10b is made more effective by reducing its attenuation.

Further, the fuel injection amount is controlled in each of the low-load intake passages 9a and 9b (of course located downstream of the communication passage 18 described later) in accordance with the intake air amount based on the output of the air flow meter 7. Solenoid valve type fuel injection nozzle 15.1
5 is arranged to ensure good fuel response.

And, the branch part of the intake passage 10 for high load is 2.
The enlarged chamber 17 is located downstream of the intake passage 12 and has a communication passage 16 that communicates the first and second high-load intake passages 10a and 10b. Above communication path 1
The passage area Acs of No. 6 is set so that pressure waves are effectively transmitted with less attenuation.
The minimum passage area of b is set to be equal to or greater than 〇 (Acs≧As).

In addition, the branch part of the main low-load intake passage 9 is
It is constituted by an enlarged chamber 19 located one downstream and having a communication passage 18 that communicates the first and second low-load intake passages 9a and 9b. The passage area Acp of the communicating passage 18 is set to be equal to or larger than the minimum passage area Ap of each low-load intake passage 9a, 9b so as to effectively transmit pressure waves (Acp≧Ap).

In addition, the above-mentioned expansion room 17, '1? functions as a surge tank for intake air during transient operations such as when the engine is accelerating or decelerating, and prevents misfires caused by breathing during acceleration or over-rich fuel during deceleration. This ensures good responsiveness.

Further, each high-load intake port 14 is provided with a high-load intake valve 20 for opening and closing the high-load intake port 14, and each low-load intake port 16 (not shown) is provided with a high-load intake valve 20 for opening and closing the high-load intake port 14. A low-load intake valve that opens and closes the intake port 16 is provided.

In each cylinder 1A, 1B, one end of each cylinder 21 and 22 opens to the atmosphere, and the other end opens to the combustion chamber 2 of each cylinder 1A, 1B through an exhaust port 23.24.
first and second exhaust passages for discharging exhaust gas from the exhaust port 2;
An exhaust valve 25.25 is provided to open and close 3.24. Although not shown, a catalyst device for purifying exhaust gas is installed at the downstream collecting portion of each exhaust passage 21, 21, 22, 22 of each cylinder IA, 1B, and the exhaust pressure is high. I'm looking forward to it.

In addition, the opening timing of the intake valve 20 for high load (opening timing of the intake port 14 for high load), t/i, the opening timing of the intake valve for low load (not shown) (opening timing of the intake port 16 for low load) 9, high load intake passage 10a.
, 10b, a strong compression wave is generated when opening. Also, the closing timing of the high-load intake valve 20 (the closing timing of the high-load intake port 14) is the same as the closing timing of the low-load intake valve. (The closing timing of the low-load intake port 13) is incorrectly set, and the high-load intake passage 10a.

10b, and prevents the opening compression wave propagated to the high-load intake port 14 at the end of the intake stroke from blowing through from the low-load intake port 13 due to inter-cylinder interference. to effectively obtain the supercharging effect.

In addition, both cylinders IA+1 via the communication passage 16
Passage length Le of high-load intake passages 10a and 10b between B
(In other words, high-load intake port) 14. Communication length between 14)
is the passage length zce of the communication passage 16 and the first zce downstream of the communication passage 16. The sum of the passage lengths Is and 1S of the second high-load intake passages 10a- and 10b (Ls = l
cs +21s) and 5000-7000rpm
It is set so that an inter-cylinder interference effect (exhaust interference effect, intake inertia effect) is obtained between both cylinders IA and IB in the rotation range of . When obtaining the exhaust interference effect, it is set to the value determined from the formula. In addition, in the above formula (■), Z is the number of cylinders, and in the case of 2 cylinders, Z = 2, and 7
20 indicates the phase difference between the cylinders, θS is the opening period of the high-load intake valve 20, and false is the compression period from the opening of the high-load intake valve 20 (opening of the high-load intake port 14) to the opening period. The period from when the compression wave propagates during the opening to perform effective supercharging to when the high-load intake valve 20 is closed (the high-load intake port 14 is closed) The invalid period is the sum of the period up to
) represents the rotation angle of the crankshaft required from generation of the opening compression wave in one cylinder to propagation to the other cylinder at the end of the intake stroke.

Also, N is the engine rotation speed N = 5000-700
Orpm, and -east- is the time required to rotate 1 degree (
seconds) represents 6ON. In addition, a is the propagation velocity (sound velocity) of the pressure wave, and 2
At 0°C a = 343%.

In addition, the passage length Le is 5000-700 Orp.
When obtaining the intake inertia effect between both cylinders 1A and iB in the rotation range of m, the value is set to a value determined from the formula: Ls-(mo θ)×dan×a 1 36ON, -4n). In addition, above (II)
In the equation, θ1 is the period from when the compression wave is substantially generated at the time of closing until the closing of the high-load intake valve 20 (when the high-load intake port 14 is closed), and the period during which the valve is closed for effective supercharging. The invalid period, which is the sum of the period from when the compression wave is propagated to when the high-load intake valve 20 closes, is about 10 to 50.
The rotation angle of the crankshaft required from the generation of the closing compression wave in one cylinder to the propagation to the other cylinder at the end of the intake stroke is represented by (Earth - θ1) -2.

Other (() is the same as in the case of formula (■) above.

Further, both cylinders 1A are connected to each other via the communication passage 18.

Passage length Lp of low-load intake passages 9a and 9b between 1B
(In other words, intake port for low load)16. Similarly, the communication length between the communication passage 18 and the passage length 'P+lP of the first and second low-load intake passages 9a and 9b downstream of the communication passage 18 are calculated as follows. The sum (Lp:lCp
+2zp) and above 5000-7000rpm
11000-20 than the standard rotation speed set between
0Orp low rotation side (e.g. 4000-5000rpm)
It is set to obtain a cylinder quantum interference effect (exhaust interference effect, intake inertia effect) between both cylinders 1A and iB.

When obtaining the exhaust interference effect, 720
60 Lp-(-+ θP-θo) x −x a
-(IUZ 36ON According to the formula, and when obtaining the intake inertia effect, 720
60 Lp=(--〇,) X X a
・ (■UZ, 36ON It is set to the value obtained by the formula. In addition, the above (1'
In formula i, θP is the opening period of the low-load intake valve, and other aspects are the same as formulas (I) and (It) above.

Note that in the formula 1 (T), ω), (1'), (H), the influence of the flow of intake air on the propagation of pressure waves is ignored.

This is because the flow velocity is smaller than the speed of sound and causes almost no change in the length of the intake passage.

Next, the operation of the first embodiment will be explained with reference to FIG. 3. When the engine rotates at a high speed of 5,000 to 7,000 rpm, which requires high output, the opening operation IC of The high-load intake passage 10 is also opened, and the high-load intake passages 10a, 1C1b are also connected to the low-load intake passages 9a, 1C1b for each cylinder 1A, 1B.
Intake air is supplied independently of 9b. At that time, the date and time when the high-load intake port 14 of one cylinder, for example, the second cylinder 1B, is opened by opening the high-load intake valve 20, or the high-load intake port 14 is closed by closing the high-load intake valve 20. The opening compression wave or the closing compression wave generated in the vicinity of the high load intake port 14 of the second high load intake passage 10b, respectively, is generated in the high load intake passage 10a between the two cylinders 1A and 1B.
, the passage length Ls of 10b is set at 5000 to 7000 rpm.
The above (I) or (n) is based on the high engine speed of
By setting the value obtained by the formula, the high-load intake port 14 of the first cylinder 1A at the end of the intake stroke passes through the second high-load intake passage 10b continuous passage 16 and the first high-load intake passage 10a. propagate to. As a result, this opening compression wave or closing compression wave forces the intake air into the combustion chamber 2 through the high-load intake port 14 of the first cylinder 1A at the end of the intake stroke, resulting in strong supercharging. (exhaust interference effect or intake inertia effect in high-load intake system).

At the same time, when the low-load intake port 16 is opened by opening the low-load intake valve of the second cylinder 1B, or when the low-load intake port 16 is closed by closing the low-load intake valve, the second Low load intake port 16 of load intake passage 9b
The opening compression wave or the closing compression wave generated in the vicinity causes the passage length LP of the low-load intake passages 9g and 9b between both cylinders 1A and 1B to be 1000 to 200 rpm from the reference rotation speed of 5000 to 7000 rpm. Above (I) on the low rotation side
or (by setting the value determined by the II'i formula, the second low-load intake passage 9b continuous passage 18-first
Supercharging is carried out via the low-load intake passage 9a to the low-load intake port 16 of the first cylinder 1A, which is also at the end of the intake stroke (exhaust interference effect or intake inertia in the low-load intake system). Effect Σ.

Similarly, in the second cylinder 1B, the opening compression wave or the opening compression wave from each intake port 13.14 of the first cylinder 1A is applied to each intake port 13.14 at the end of the intake stroke. Supercharging is carried out through propagation.

Therefore, in this way, 50% in a high-load intake system
The supercharging effect due to inter-cylinder interference effect (exhaust interference effect, intake inertia effect) in the engine high speed range of 00 to 700 rpm, and the above 5000 to 7000 rpm in the low-load intake system.
rpmJ: As shown in Figure 4, due to the supercharging effect due to the inter-cylinder interference effect in the low rotation range, the charging efficiency increases from the mid to high engine rotation range, making the output more effective. There are seven things you can do to improve your skills. In addition, in FIG. 4, each intake passage 9a + 9b, ioa, 1 of each cylinder lA, 1B
In contrast to the conventional example (indicated by the broken line) in which 0b is made independent from each other, the inter-cylinder interference effect (indicated by the solid line) with the high-load intake system set at 6000 rpm is compared to the 400 rpm in the low-load intake system.
Inter-cylinder interference effect based on rpm (indicated by a dashed line)
The output torque characteristics of the engine are shown in the case where the following are obtained.

In that case, the high-load intake passage 10a is a pressure wave propagation path for obtaining the exhaust interference effect and the intake inertia effect.
, 10b have a larger passage area and shorter passage length than the low-load intake passages 9a and 9b! ＝に、J：
It has low resistance to pressure wave propagation, effectively exerts the inter-cylinder interference effect in the high-load intake system, and meets output requirements especially at high engine speeds (5000 to 700 rpm), which require high output. It's advantageous.

Further, the communication passages 16 and 18 are located downstream of the primary production 11 and the secondary production 12, respectively, and each communication passage 1<
The passage area Acp, Ace of S, 18 is defined as each intake passage 9a.
Minimum passage area Ap, As of 19b, 10a, 10b
Since the above has been made, the above answers 11 and 12 and each communication path 16.
The pressure waves are not attenuated by the pressure wave 18 itself (the above-mentioned exhaust interference effect and intake inertia effect can be effectively exerted).

Furthermore, by making the opening timing of the high-load intake port 14 earlier than that of the low-load intake port 13, the compression wave when the high-load intake port 14 opens is particularly strong (
This is effective in improving the supercharging effect due to the exhaust interference effect. In addition, by making the closing timing of the high-load intake port 14 different from that of the low-load intake port 13, a strong compression wave can be generated at the time of opening, which is advantageous in improving the intake inertia effect, and there is no interference between cylinders. This is advantageous in that it can prevent compression waves from blowing through from the low-load intake port 16.

Further, the fuel injection nozzle 15 serving as a fuel supply device is located in the low-load intake passage 9a downstream of the communication passage 18.

9b, to obtain an inter-cylinder interference effect." 2) prevents deterioration of fuel response due to long intake passages, ensuring good fuel response, and ensuring good fuel response during full operation. It is sufficient to install only the low-load intake passages 9a and 9b, which can supply intake air and fuel in the area, and the fuel supply system can be simplified.

In addition, the supercharging effect due to the exhaust interference effect and the intake inertia effect is determined by the position of the communication passage 16, 18 and its passage area,
and both cylinders 1A and iB via the communication passage 16.18.
This can be obtained by setting the lengths Ls, Lp, etc. of the high-load intake passages 1°a, 10b and the low-load intake passages 9a, 9b as described above (no need for a supercharger, etc.). Therefore, only a slight design change to the existing intake system is required, and the structure is extremely simple, so it can be implemented easily and at low cost.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but also includes various other modifications. For example, in the above embodiment, the low-load and high-load intake passages 9a are provided in each cylinder IA and IB.

9b, 10a, and 10b are opened into the combustion chamber 2 through independent low-load and high-load intake ports 13.14, but as in the second actual gal example shown in FIG. The combustion chamber 2 may be opened through the intake port 26, and the intake port 26 may be opened and closed by a single intake valve 27, and the same effects as in the first embodiment can be achieved. (In FIG. 5, the same parts as in the first embodiment are given the same reference numerals and their explanations are omitted.) In addition, in the first embodiment, an example applied to a two-cylinder four-stroke engine is shown. However, the present invention can of course be applied to various other types of dual induction type multi-cylinder engines.3For example, as shown in FIG. A third embodiment applied to an engine is shown (the same parts as in the first embodiment are given the same reference numerals and detailed explanation thereof is omitted).
.

In this example, the high-load intake passages 10 for each cylinder 18 to 1D
8 to 10 dUThe communication passages 16' are formed by the expansion chamber 17' downstream of the secondary valve 12, and the communication passages 9a to 9d are connected to the communication passage 1 formed by the expansion chamber 19' downstream of the primary valve 11.
8', and a fuel injection nozzle 15 is disposed in each of the low-load intake passages 9a to 9d downstream of the communication passage 18'. Also, the high-load intake passages 10a to 10 between the cylinders 1A to 1D are connected via the communication passages 16' and 18'.
d and the passage length Ls of the low-load intake passages 9a to 9d,
When obtaining the exhaust interference effect, Lp is determined by the above (I) or (
The first term on the right side of equation I'1 (rotation angle required from generation of compression wave to propagation during opening), different angles (see Figure 9), Ls(p
)=(θ5(p)-180-0°) .

Note that the same applies to a 3-cylinder 4-stroke engine, although not shown, and the lengths of each passage Ls and Lp are set as in (1) above.
, (r5, (n), <n').

In addition, in the third embodiment (four-cylinder four-cycle engine), each intake passage 9 corresponding to the first and fourth cylinders iA and 1D
Passage length lpl of a, 9d, 1Qa, 10d
, lP4. IB□ and lS4 are the same, lP, = 1rP
4>'P2 +'p:l'g21's3 similarly, lp
2'='! ,8>zs.

-163. Therefore, 1st cylinder 1A-3rd cylinder 1C
In the ignition order of the fourth cylinder 1D and the second cylinder 1B, the passage lengths Lp and LstI'i between consecutive combustion cylinders are all the same. That is, Lp = e'px(lP4) + eP2C1P3)
"""'81 (lS4) 10'82 ('8B), so each intake passage for each cylinder 16-1D?a-9d, 1
It is preferable to branch from a location near the 0a-10dd expansion chambers 17' and 19'.

Furthermore, as for the inter-cylinder interference of the exhaust interference effect and the intake inertia effect, in the first embodiment (two-cylinder four-cycle engine), the high-load intake system
In the high rotational speed range of pm, the low-load intake system was designed to obtain inter-cylinder interference effects at lower rotational speeds, but conversely, the low-load intake system had a rotation speed of 5000 to 70QQrpin.
In the high-speed rotation range, the high-load intake system may be set to obtain the inter-cylinder interference effect at lower rotation speeds, but as described above, the settings in the above embodiment are preferable in terms of the supercharging effect. . In the case of a general two-cylinder engine, the action process of inter-cylinder interference is as shown in Fig. 7, the exhaust interference effect (indicated by the solid line arrow) and the intake inertia effect (indicated by the broken line arrow), as described above. acts alternately from the first cylinder to the second cylinder, and from the second cylinder to the first cylinder.In addition, in the case of a three-cylinder engine, as shown in Fig. 8, both of the above As in the case of a two-cylinder engine, the effect acts sequentially from the first cylinder to the second cylinder, from the second cylinder to the third cylinder, and from the third cylinder to the first cylinder.Furthermore, in the case of a four-cylinder engine, K1- 1:
, as shown in Fig. 9, the intake inertia effect is caused by the ignition order being reversed: 1st cylinder - 3rd cylinder, 3rd cylinder - 4th cylinder, 4th cylinder - 2nd cylinder, 2nd cylinder - 1st cylinder. On the contrary, the exhaust interference effect acts from the cylinder whose phase is delayed by 180', and the effect is applied from the 3rd cylinder to the 1st cylinder, the 4th cylinder to the 3rd cylinder, and the 2nd cylinder to the 4th cylinder. , from the first cylinder to the second cylinder, and from the third cylinder to the first cylinder. Therefore, the passage lengths Ls and Lp between the cylinders that cause inter-cylinder interference may be set so as to obtain the exhaust interference effect or the intake inertia effect.

In addition, in the embodiment described in ``1'', the primary valve 11 is provided redundantly in the main low-load intake passage 9, but the primary valve 11 is connected to the main low-load intake passage 9 and A type provided in the main intake passage 5 upstream of the branching part with the load intake passage 10 can also be adopted.

As explained above, according to the present invention, in a multi-cylinder engine equipped with two independent intake passages, one for low load and one for high load, when the engine rotates at a high speed of 5,000 to 7,000 rpm, A supercharging effect is obtained by the inter-cylinder interference effect (exhaust interference effect, intake inertia effect) on one side of the load intake system, and the above 5000-700Orpm
Since the supercharging effect is obtained by the inter-cylinder interference effect in the other intake system on the low rotation side of 1000 to 2000 rpm than the standard rotation speed of the With 111 simple configuration due to design changes,
It is possible to effectively improve the engine output by increasing the charging efficiency from the medium speed range to the high speed range of the engine, and thus it can greatly contribute to the ease of implementation of measures to improve the engine output and cost reduction.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and FIGS. 1 and 2 are an explanatory diagram of the overall configuration and a schematic diagram of the essential parts of the first embodiment, and FIG. 3 is an explanatory diagram showing the intake stroke of the first embodiment. , FIG. 4 is a diagram showing output torque characteristics, FIG. 5 is a schematic diagram of main parts showing the second embodiment, FIG. 6 is a diagram corresponding to FIG. 1 showing the third embodiment, and FIG. 7 is a diagram showing the output torque characteristics.
9 to 9 are explanatory diagrams showing inter-cylinder interference in two-cylinder, three-cylinder, and four-cylinder engines, respectively. 1A to 1D... 1st to 4th cylinders, 2... Combustion chamber, 5...
・Main intake passage, 7 Air flow meter, 9... Main low load intake passage, 9a to 9d... 1st to 4th low load intake passage, 10 Main high load intake passage, 108 to 10d...
1st to 4th high-load intake passages, 11...primary valve, 12
...Secondary valve, 15...Fuel injection nozzle, 16, 1
6'...Communication path, 18. '18'...Communication path.

Claims (1)

[Claims] ill The intake passage has a low load intake passage and a high load intake passage that open independently to each cylinder, and the intake passage has a primary intake passage that changes the amount of intake air flowing through the low load intake passage. An intake system for an engine having a valve and a secondary valve that changes the amount of intake air flowing through a high-load intake passage, the intake system comprising a valve and a secondary valve that changes the amount of intake air flowing through a high-load intake passage. The high-load intake passages are connected to each other by a communication passage having a passage area larger than the minimum passage area of each intake passage, and the low-load intake passage and high-load intake passage between each cylinder are connected via the communication passage. The passage length is set so that the pressure wave generated at the opening of one cylinder at high engine/engine revolutions of 5,000 to 7,000 rpm propagates to the other cylinder at the end of the intake stroke to perform supercharging. , the pressure wave generated at the opening of one cylinder at the low rotation side of 1000 to 2000 rpm, compared to the standard rotation speed set when the capacity is between 5000 and 7000 rpm, propagates to the other cylinder at the end of the intake stroke, causing supercharging. An engine intake system characterized in that it is set to perform.