JPH06330758A - Intake system of engine - Google Patents

Abstract

PURPOSE:To provide an intake system of an engine capable of stratifying sufficiently a mixture at the low rotation speed to improve the ignition property and combustion quality effectively and improving sufficiently the intake filling efficiency at high rotation speed. CONSTITUTION:In an engine CE, a VICS valve 37 is closed at the low rotation speed, a mixture is supplied from a mixture supply port 7 into a combustion chamber 2 and concentrated around an ignition plug 8 to stratify the inside of the combustion chamber 2 to improve the ignition property and combustion quality of the mixture. The pulsation of pressurized air supplied to the mixture supply port 7 from an air pump 33 is damped by an expansion chamber 32. The variation of an inflow amount (flow speed) of the mixture from the mixture supply port 7 to the combustion chamber 2 is reduced to stabilize the stratification. At the high speed rotation, the VICS valve 37 is opened to perform the inertial supercharge in the expansion chamber 32 of pressure inverting section on the second intake port 4 side to improve the filling efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine intake device.

[0002]

2. Description of the Related Art Generally, an engine has a problem that the ignitability and the combustibility of an air-fuel mixture are deteriorated at a low rotation speed or a low load, and the problem is particularly remarkable in a lean burn engine. Therefore, in recent years, a method of concentrating fuel around the spark plug at the time of low rotation or low load to stratify the air-fuel mixture in the combustion chamber to enhance ignitability and combustibility has been widely used. On the other hand, it is required to increase the intake charging efficiency as much as possible in order to improve the engine output at high rotation speed. For this reason, conventionally, a method (inertial supercharging) of increasing intake charge efficiency by utilizing the intake inertia effect at high rotation speed has been widely used (see, for example, JP-A-3-279620).

Specifically, an engine has been proposed in which the injection port of the fuel injection valve is arranged toward the ignition plug in order to promote stratification of the air-fuel mixture at low rotation speed or low load. However, in such an engine, since the fuel is injected from the fuel injection valve with a strong force, the fuel passes through the vicinity of the spark plug, and there is a problem that the mixture cannot be effectively stratified.

In order to improve this, a fuel injection valve that opens toward the vicinity of a spark plug disposed in the center of the combustion chamber is provided, while the intake port is a swirl generation port, and the intake port is inside the combustion chamber at low speed or low load. An engine has been proposed in which a swirl is generated and fuel injected from a fuel injection valve is collected around the spark plug by the swirl. However, even if the stratification is promoted by the swirl as described above, the fuel injected from the fuel injection valve still has a strong momentum, and thus tends to pass through the vicinity of the spark plug.

Therefore, the air-fuel mixture supply port opening toward the vicinity of the spark plug, the fuel injection valve for injecting fuel into the air-fuel mixture supply port, and the air-fuel mixture for a predetermined period between the latter half of the intake stroke and the first half of the compression stroke. An engine has been proposed which is provided with an air-fuel mixture supply port opening / closing valve that opens the supply port, and concentrates a weakly-energized air-fuel mixture flowing from the air-fuel mixture supply port into the combustion chamber around the spark plug to promote stratification. (See, for example, Japanese Utility Model Laid-Open No. 62-18335).

[0006]

By the way, in the conventional engine having such a mixture supply port,
From the latter half of the intake stroke to the first half of the compression stroke where the cylinder pressure rises, the air-fuel mixture is supplied from the air-fuel mixture supply port into the combustion chamber, so the air supplied to the air-fuel mixture supply port is pressurized using an air pump, etc. I am trying. However, since the pressurized air discharged from the air pump is inevitably accompanied by pulsation, the pulsation changes the outflow rate of the air-fuel mixture from the air-fuel mixture supply port into the combustion chamber, which causes There is a problem that the distribution position of the air-fuel mixture changes, and therefore the ignitability and combustibility are not sufficiently improved.

Further, since the intake air supply force to the combustion chamber of the air-fuel mixture supply port decreases at high rotation speed, there is a problem that the intake charge efficiency decreases, that is, engine output decreases in the high rotation speed region. As mentioned above,
At the time of high rotation, the method of increasing the intake charging efficiency by utilizing the intake inertia effect is often used, but in the conventional engine, the surge tank is used as the pressure reversal part, so the propagation path length of the pressure wave is compared. Therefore, there is a problem that the rotation region where the inertial effect is effective cannot be brought to the high rotation side so much, and the intake charging efficiency at the high rotation cannot be sufficiently increased.

The present invention has been made in order to solve the above-mentioned conventional problems. When the engine speed is low, the air-fuel mixture can be sufficiently stratified to effectively enhance its ignitability and combustibility. An object of the present invention is to provide an intake system for an engine that can sufficiently increase intake charging efficiency during rotation.

[0009]

To achieve the above object, a first aspect of the present invention is to open a combustion chamber while supplying pressurized air from a pressurized air supply source and supplying fuel from a fuel supply source. The air-fuel mixture supply port that generates the air-fuel mixture with the pressurized air and the fuel and the air-fuel mixture that opens the opening of the air-fuel mixture supply port to the combustion chamber for a predetermined period between the latter half of the intake stroke and the first half of the compression stroke. In an intake device for an engine provided with a supply port opening / closing valve, an expansion chamber connected to an upstream part of a mixture supply port, a communication part communicating the expansion chamber and a midway part of the intake port, and the communication part. A communication part opening / closing valve for opening and closing is provided so that the expansion chamber and the communication part have an intake path length from the expansion chamber to the downstream end of the intake port shorter than an intake path length from the surge tank to the downstream end of the intake port. Formed in Part off valve provides an air intake system for an engine, characterized by being adapted to be opened at a predetermined high speed region.

A second invention is the engine intake system according to the first invention, wherein the intake port is provided with a first intake port which is a swirl generating port, and a swirl control valve which is closed in a predetermined operating region. An intake device for an engine, characterized in that it is divided into two intake ports, and a communication part is formed so as to connect the expansion chamber and a middle part of the second intake port.

A third aspect of the present invention is the engine intake system according to the first aspect, wherein the intake port includes a first intake port which is a swirl generation port, and a swirl control valve which is closed in a predetermined operating region. It is divided into two intake ports, and the first intake port and the second intake port are merged on the upstream side for each cylinder, and the communication part is formed so as to communicate the expansion chamber and the merge part. ,
An intake system for an engine, wherein the communication passage opening / closing valve is partially opened in a region where the swirl control valve is closed, and is fully opened in a region where the swirl control valve is opened.

According to a fourth aspect of the present invention, in the intake system for an engine according to any one of the first to third aspects, the communication part opening / closing valve is opened in a predetermined high load / high rotation range, and the high load is set. -Providing an intake system for an engine, characterized in that the fuel supply to the air-fuel mixture supply port is stopped or reduced in the high rotation speed region, and the fuel supply from the intake port is substantially started.

A fifth aspect of the present invention is the intake system for an engine according to any one of the first to third aspects, wherein the mixture supply port has an average Mach coefficient of 0.
Provided is an intake device for an engine, wherein the intake port is formed to have a number of 4 or more, and the intake port is formed to have an average Mach coefficient of less than 0.4 in a high rotation speed region.

According to a sixth aspect of the present invention, in the engine intake system according to the second aspect, a relief passage for relieving the air pressurized by the pressurized air supply source to the first intake port side is provided. Provided is a characteristic engine air intake device.

According to a seventh aspect of the present invention, in the intake system for an engine according to the second aspect, a first relief passage for relieving air pressurized by a pressurized air supply source toward both intake ports, and a first intake port. A second relief passage that only relieves to the side, and a relief switching means that switches between relief of pressurized air to the first relief passage or relief to the second relief passage are provided, and the relief switching means is provided. When the swirl control valve is open, the pressurized air is relieved to the first relief passage, and when the swirl control valve is closed, the pressurized air is relieved to the second relief passage. An intake system for an engine is provided.

According to an eighth aspect of the present invention, while opening to the combustion chamber, pressurized air is supplied from a pressurized air supply source and fuel is supplied from a fuel supply source to generate a mixture of these pressurized air and fuel. An intake device for an engine provided with a mixture supply port to be generated and a mixture supply port opening / closing valve that opens an opening of the mixture supply port to a combustion chamber for a predetermined period between the latter half of the intake stroke and the first half of the compression stroke. In, the intake port is divided into a first intake port that is a swirl generation port and a second intake port that is equipped with a swirl control valve that is closed in a predetermined operating region, and is connected to an upstream part of the mixture supply port. The expansion chamber, a communication part that communicates the expansion chamber with the middle part of the second intake port, and a communication part opening / closing valve that opens and closes the communication part, and the expansion chamber and the communication part are connected to each other. From the second Intake path length reaching the exhaust port downstream end is formed to be shorter than the intake path length extending in the second intake port downstream end from the surge tank, communicating opening and closing valve,
An intake system for an engine, characterized in that the swirl control valve is adapted to be opened in an operating region where it is opened.

In a ninth aspect of the present invention, in the intake system for an engine according to the eighth aspect, the air-fuel mixture supply port is formed so that the average Mach coefficient is 0.4 or more in the low rotation speed region, and the intake port is Provided is an intake system for an engine, which is formed so that an average Mach coefficient in a high rotation region is less than 0.4.

According to a tenth aspect of the present invention, in the intake system for an engine according to the eighth aspect, a relief passage for relieving the air pressurized by the pressurized air supply source to the first intake port side is provided. Provided is a characteristic engine air intake device.

[0019]

EXAMPLES Examples of the present invention will be specifically described below. <First Embodiment> As shown in FIG. 1 and FIG.
A combustion chamber 2 is provided in each cylinder 1 of a four-cylinder engine CE including cylinders (# 1 to # 4), and an intake-side half of a ceiling portion of each combustion chamber 2 (left in FIGS. 1 and 2). While the first and second intake ports 3 and 4 are opened in one half), the exhaust side half (Fig. 1,
The first and second exhaust ports 5 and 6 are opened in the right half portion in FIG. Further, the first intake port 3 and the second intake port 4
Between the combustion chamber 2 and the air-fuel mixture supply port 7
Is open. Further, an ignition plug 8 is arranged substantially in the center of the combustion chamber 2 in a plan view.

Here, the first intake port 3 is connected to the cylinder 1
A tangential port that opens substantially in the circumferential direction of the (combustion chamber 2), and swirl is generated in the combustion chamber 2 by the air flowing into the combustion chamber 2 from the first intake port 3. ing. That is, the first intake port 3 is a swirl generation port. The first intake port 3 may be a helical swirl generation port.

The first intake port 3 is opened and closed by the first intake valve 9 at a predetermined timing in synchronization with the crankshaft 19 (for example, 13 ° before top dead center in terms of crank angle). ~ Valve open at 43 ° after bottom dead center).
The first intake valve 9 is driven by a valve mechanism (not shown). Similarly, the second intake port 4 is opened and closed by the second intake valve 10. Also, the first and second exhaust ports 5 and 6 are respectively the first and second exhaust ports.
It is adapted to be opened and closed by the exhaust valves 11 and 12. Further, the air-fuel mixture supply port 7 is opened and closed by the air-fuel mixture supply port opening / closing valve 20 at a predetermined timing synchronized with the crankshaft 19 between the latter half of the intake stroke and the first half of the compression stroke (for example, The valve is open 90 ° after top dead center to 90 ° after bottom dead center in terms of crank angle.

Further, a first fuel injection valve 13 which faces the first intake port 3 and injects fuel into the air in the first intake port 3 is provided, while the first fuel injection valve 13 faces the mixture supply port 7 and the mixture A second fuel injection valve 14 that injects fuel into the air in the supply port 7 is provided. The downstream ends of the first and second exhaust ports 11 and 12 are connected to the independent exhaust passage 15, respectively. The second fuel injection valve 14 corresponds to the "fuel supply source" described in the claims.

In the above-mentioned structure, the engine CE basically has a mixture from the first and second intake ports 3 and 4 into the combustion chamber 2 when the first and second intake valves 9 and 10 are opened. Is inhaled, this mixture is compressed by the piston 16, and the spark plug 8
When the first and second exhaust valves 11 and 12 are opened, the combustion gas (exhaust gas) is ignited and burned by the first and second exhaust ports 5,
It is designed to be discharged to the independent exhaust passage 15 via 6. Along with this, the piston 16 reciprocates in the cylinder axis direction in the cylinder 1, and this reciprocating motion is converted into rotational motion via the connecting rod 17 and the crank pin 18 and transmitted to the crank shaft 19. ing.

However, in a predetermined operation region where the ignition / combustibility of the air-fuel mixture is deteriorated, such as in the low rotation / low load region,
As described later, the mixture supply port 7 to the combustion chamber 2
An air-fuel mixture is supplied to the inside, and a rich air-fuel mixture layer is formed (stratified) around the ignition plug 8 by this air-fuel mixture to enhance ignitability and combustibility. Specifically, the second fuel injection valve 14 is generally opened before the mixture supply port opening / closing valve 20 is opened.
Fuel is injected into the pressurized air in the mixture supply port 7 to generate a rich mixture having a relatively high pressure in the mixture supply port 7, and the mixture supply port opening / closing valve 20 is opened. The air-fuel mixture is made to flow out to the vicinity of the spark plug 8. In this case, since the air-fuel mixture flowing out from the air-fuel mixture supply port 7 into the combustion chamber 2 is not so strong in momentum, it is just concentrated around the ignition plug 8 and the interior of the combustion chamber 2 is stratified to improve the ignitability and combustibility. It will be done.

By the way, the throat portions of the first and second intake ports 3 and 4 have a relatively large diameter so that the Mach coefficient at high rotation is less than 0.4. That is, generally, the Mach coefficient in the intake port increases as the engine speed increases, but when the Mach coefficient becomes 0.4 or more, the flow resistance of the air in the port increases rapidly and the air flow becomes saturated. Even if the engine speed is increased, the air flow rate per unit time hardly increases. Therefore,
In this way, the Mach coefficient is kept below 0.4 so that the air flow rate, that is, the engine output effectively increases as the engine speed increases. As a result, the engine output at the time of high rotation is increased and the controllability of the engine is improved.

On the other hand, the throat portion of the air-fuel mixture supply port 7 has a relatively small diameter so that the Mach coefficient at low speed becomes 0.4 or more. Therefore, the flow rate (flow velocity) of air or air-fuel mixture flowing into the combustion chamber 2 from the air-fuel mixture supply port 7 is substantially constant regardless of the engine speed. Therefore, the air-fuel mixture flowing from the air-fuel mixture supply port 7 into the combustion chamber 2 is distributed in the combustion chamber 2 around the ignition plug 8 at a substantially constant position, and the stratification of the air-fuel mixture is stabilized. . In this case,
The flow rate per cycle decreases in inverse proportion to the increase in engine speed.

In order to supply air to the combustion chamber 2 of each cylinder, a common intake passage 21 having an upstream end open to the atmosphere is provided, and the common intake passage 21 is provided with an air cleaner 30 and an air flow sensor 22 in order from the upstream side. And throttle valve 23
And are provided. The downstream end of the common intake passage 21 is connected to the first and second surge tanks 24 and 25 that stabilize the flow of air. The engine width direction
The second surge tank 2 as viewed in the left-right direction in FIGS. 1 and 2
5 is located closer to the engine body than the first surge tank 24.

The first surge tank 24 has a first surge tank 24 for each cylinder.
The upstream end of each independent intake passage 26 is connected, and the downstream end of each first independent intake passage 26 is connected to the corresponding first intake port 3. On the other hand, the second surge tank 25 is connected to the upstream end of the second independent intake passage 27 for each cylinder, and the downstream end of the second independent intake passage 27 is connected to the corresponding second intake port 4. . Here, a swirl control valve 28 (hereinafter, abbreviated as S valve 28) is provided in each second independent intake passage 27. These S valves 28 are provided to adjust the swirl strength, and the swirl is strengthened as the opening degree of the S valve 28 is smaller. That is, the smaller the opening degree of the S valve 28, the larger the proportion of the air flowing into the combustion chamber 2 through the first intake port 3, which is the swirl generation port, and the swirl is strengthened.

In order to supply air to the air-fuel mixture supply port 7, a pressurized air passage 31 provided with an air pump 33 is provided, and the upstream end of this pressurized air passage 31 has a common intake passage 2
1 is connected to a portion downstream of the air flow sensor 22 and upstream of the throttle valve 23. The downstream end of the pressurized air passage 31 is connected to the expansion chamber 32 having a predetermined capacity. An independent pressurizing air passage 29 for each cylinder is connected to the expansion chamber 32, and a downstream end of the independent pressurizing air passage 29 is connected to the corresponding mixture supply port 7. Here, the expansion chamber 32 is disposed adjacent to the upper surface of the second independent intake passage 27 at a position closer to the engine body than the second surge tank 25 when viewed in the engine width direction. Then, a communication hole 38 (communication part) for communicating the expansion chamber 32 and each of the second independent intake passages 27, and a communication part opening / closing valve 37 (hereinafter, abbreviated as VICS valve 37) for opening / closing the communication hole 38. And are provided. The air pump 33 corresponds to the "pressurized air supply source" described in the claims.

The expansion chamber 32 is primarily formed by the air pump 3
The pulsation of the pressurized air discharged from No. 3 is damped, and the fluctuation of the flow velocity of the air-fuel mixture flowing into the combustion chamber 2 from the air-fuel mixture supply port 7 is not reduced in a predetermined operation region (stratified combustion region) described later. It is provided in order to prevent this, stabilize the stratification of the air-fuel mixture in the combustion chamber 2, and enhance the ignitability and combustibility. However, the expansion chamber 32 is also used as a pressure reversal portion for inertial supercharging in a predetermined high rotation region, as will be described later, whereby the intake charging efficiency in the high rotation region, that is, the engine output is increased. ing.

A first relief passage 34 for connecting a portion of the pressurized air passage 31 downstream of the air pump 33 and a portion of the common intake passage 21 slightly upstream of the throttle valve 23.
The first relief passage 34 is provided with a relief switching valve 35 (relief switching means), which is a three-way valve. A second relief passage 36 whose downstream end is connected to the first surge tank 24 is connected to the third terminal of the relief switching valve 35.

As described above, the air supplied to the air-fuel mixture supply port 7 is pressurized in this manner, as described above, after the air-fuel mixture supply port opening / closing valve 20 reaches the bottom dead center.
This is because the air-fuel mixture in the air-fuel mixture supply port 7 cannot be pushed into the combustion chamber 2 with air at normal pressure because the air-fuel mixture is opened even after 0 is closed. Further, the relief of the pressurized air to the first intake port side or the second intake port side via the first and second relief passages 34, 36 can increase the intake charging efficiency by the pressurized air, Moreover, the swirl can be strengthened. Specifically, S
When the valve 28 is opened, the first and second intake ports 3,
Since compressed air is supplied to the combustion chamber 2 from the
While the relief efficiency is increased through the relief passage 34 toward both intake ports, air is supplied to the combustion chamber 2 only from the first intake port 3 when the S valve 28 is closed, so pressurized air is supplied. Only the first intake port side is relieved via the second relief passage 36. Switching of the relief path is performed by the relief switching valve 3 according to a signal applied from the control unit C.
It is done by 5.

A drive mechanism for opening and closing the S valve 28 and the VICS valve 37 will be described below. S valve 28 for each cylinder
Is attached to one S valve valve shaft 41, and this valve shaft 41
A negative pressure responsive first actuator 42 is driven to open and close in accordance with a signal applied from the control unit C via the. Specifically, the first
The pressure chamber of the actuator 42 is connected to a downstream end of a first negative pressure supply passage 45 in which a vacuum pump 43 and a vacuum chamber 44 are provided on the upstream side. A solenoid valve 46 is provided. Here, the first solenoid valve 46 operates in accordance with a signal applied from the control unit C.
The S valve 28 is opened and closed by controlling the negative pressure applied to the pressure chamber of the actuator 42.

The VICS valve 37 of each cylinder is one VIC
It is attached to the valve shaft 48 for S valve, and through this valve shaft 48,
According to the signal applied from the control unit C,
It is adapted to be opened and closed by a second actuator 49 of negative pressure responsive type. Here, a second negative pressure supply passage 50 having an upstream end connected to the vacuum chamber 44 is connected to the pressure chamber of the second actuator 49, and a second solenoid valve 51 is further connected to the second negative pressure supply passage 50. It is installed. Here, the second solenoid valve 51
Adjusts the negative pressure applied to the pressure chamber of the second actuator 49 according to a signal applied from the control unit C to open and close the VICS valve 37.

The control unit C uses the engine speed, engine load (throttle opening), etc. as control information, and controls the S valve 28 and VIC according to the operating state of the engine CE.
The S valve 37 is controlled so that the air-fuel mixture is stratified at low speed to enhance its ignitability and combustibility, while the intake charging efficiency is increased at high speed. The control method of the opening / closing control of the valve 28 and the VICS valve 37 and the control associated therewith will be described.

As shown in FIG. 5, the S valve 28 is closed in a region (stratified combustion region) on the low rotation / low load side of the curve G ₂ and is opened in other regions. On the other hand, VICS valve 3
7 is closed in a low rotation region where the engine speed is equal to or lower than a predetermined value N ₁ , and is opened in a high rotation region where N ₁ exceeds N ₁ .
Here, the second fuel injection valve 14 injects fuel in the stratified combustion region according to a signal from the control unit C, but stops or reduces fuel injection in other regions. As a result, premixed uniform combustion is performed and high output is obtained. The relief switching valve 35 relieves the pressurized air to the first relief passage 34 in the area where the S valve 28 is opened and relieves the pressurized air in the area where the S valve 28 is closed according to a signal from the control unit C. The two-relief passage 36 is designed to be relieved.

When the operating state of the engine CE is in the stratified charge combustion region, the S valve 28 and the VICS valve 37 are closed. In this case, all the air supplied from the intake port side to the combustion chamber 2 flows into the combustion chamber 2 via the first intake port 3, and a strong swirl is generated in the combustion chamber 2. Further, since the fuel is injected from the second fuel injection valve 14, a weakly-powered air-fuel mixture is supplied from the air-fuel mixture supply port 7 into the combustion chamber 2, and the air-fuel mixture is concentrated around the spark plug 8. Therefore, a strong swirl and air-fuel mixture supply port 7
The air-fuel mixture in the combustion chamber 2 is sufficiently stratified by the air-fuel mixture supplied from the
Combustibility is enhanced. Further, as described above, since the Mach coefficient is 0.4 or more and the pulsation of the pressurized air is reduced or prevented by the expansion chamber 32, the unit of the air-fuel mixture flowing from the air-fuel mixture supply port 7 into the combustion chamber 2 The flow rate (flow velocity) per hour is almost constant and uniform regardless of the engine speed, and stable stratification is performed. In this case, the pressurized air is relieved into the first surge tank 24 through the second relief passage 36, whereby the intake charging efficiency is increased and the swirl is strengthened.

When the engine operating condition is that the engine speed is N ₁ or less and is outside the stratified charge combustion region, the S valve 28 is opened and the first and second intake ports 3 and 4 and the air-fuel mixture supply port 7 are opened. Air is supplied into the combustion chamber 2 via the. In this case, since the VICS valve 37 is closed, the first and second
The intake system on the side of the intake ports 3 and 4 and the intake system on the side of the air-fuel mixture supply port 7 are separated from each other, and there is no particular interaction between them. In this case, the pressurized air is relieved in the surge tanks 24, 25 through the first relief passage 34, and the intake charging efficiency is improved.

In the high rotation speed region where the engine speed exceeds N ₁ , both the S valve 28 and the VICS valve 37 are opened,
Further, the fuel injection from the second fuel injection valve 14 is stopped.
In this case, since the VICS valve 37 is opened, inertial supercharging is performed on the second intake port 4 side, with the expansion chamber 32 serving as the pressure reversal portion (volume portion). As mentioned above, the expansion chamber 32
Is located closer to the engine body than the second surge tank 25, so the path length from the expansion chamber 32 to the downstream end of the second intake port 4 (the opening to the combustion chamber 2) is relatively short. Become. Therefore, the tuned natural frequency of inertial supercharging using the expansion chamber 32 as a pressure reversal portion is increased, and thus a high inertial effect is obtained in such a high rotation region, intake charging efficiency is increased, and engine output is increased. In this case, since the pressurized air is relieved in the surge tanks 24, 25 via the first relief passage 34, the intake charging efficiency is further enhanced. In this high rotation speed region, when the engine speed is relatively low, inertial supercharging using the first surge tank 24 or the second surge tank 5 as the pressure reversal unit is, of course, also performed.

When the S valve 28 and the VICS valve 37 are controlled in this manner, the characteristic of the output torque T of the engine CE with respect to the engine speed is as shown by a curve G ₁ in FIG. In FIG. 5, an arrow X ₁ indicates the effect of improving the full-open torque by inertial supercharging with the expansion chamber 32 as the pressure reversal portion in the high rotation region where the engine speed exceeds N ₁ .

It should be noted that the VICS valve 37 is not opened or closed depending on whether the engine speed is N ₁ or less as described above, but the VICS valve 37 is closed in a region where the S valve 28 is closed, that is, a stratified combustion region. The VICS valve 37 may be opened in the area where the valve 28 is opened. FIG. 6 shows the characteristic of the intake charge efficiency ηv during WOT with respect to the engine speed in this case (curve G ₃ ). In FIG. 6, the curve G ₄ shows the intake charge efficiency when the expansion chamber 32 is not provided, and therefore the arrow X ₂ shows the effect of improving the intake charge efficiency by providing the expansion chamber 32.
The curve G ₅ indicates the boundary between the stratified charge combustion region and other regions.

As described above, the pressurized air in the pressurized air passage 31 is relieved to the first intake port side or the second intake port side to enhance the intake charging efficiency. The effect of improving the intake filling efficiency by the relief of the pressurized air is shown. In FIG. 7, in the low rotation speed region where the engine speed is N ₁ or less, the curve G ₆ is the engine output torque at WOT when the relief of the pressurized air is performed, and the curve G ₇ is the relief of the pressurized air. Output torque when not performed. As is clear from FIG. 7, the engine output torque in the low rotation speed region is increased by such relief. In FIG. 7, the engine speed is N
The output torque improving effect in the high rotation region exceeding ₁ is due to the inertia supercharging using the expansion chamber 32 as the pressure reversal portion.

When the S valve 28 is closed,
By relieving the pressurized air to the first surge tank 24 through the second relief passage 36, the first intake port 3
The flow velocity of the air in the inside is increased, whereby the swirl is strengthened, and the ignitability / combustibility of the air-fuel mixture in the combustion chamber 2 is further enhanced. FIG. 8 shows the strength of air turbulence, that is, the swirl strength (curve G) when performing relief of pressurized air when the S valve 28 is closed in a low speed region where the engine speed is equal to or lower than a predetermined value N _{1. 13} ) and the turbulence intensity (curve G ₁₄ ) when the relief of the pressurized air is not performed. As is clear from Fig. 8, the turbulence strength due to the relief of the pressurized air
(Swirl strength) is increased. In FIG. 9, a curve G ₁₅ is the flow rate of pressurized air discharged from the air pump 33, and a straight line G ₁₆ is the flow rate of air flowing into the combustion chamber 2 from the mixture supply port 7. Here, the difference between G ₁₅ and G ₁₆ is from the pressurized air passage 31 to the first relief passage 34 or the second relief passage 34.
The flow rate of the pressurized air that is relieved to the relief passage 36 is shown. The pressurized air thus relieved enhances the intake charging efficiency and the swirl.

<Second Embodiment> The second embodiment will be described below with reference to FIGS. 3 and 4. The basic part of the second embodiment is common to the first embodiment shown in FIGS. 1 and 2. Therefore, only differences from the first embodiment will be described below to avoid duplication of description. In addition, in FIG. 3 and FIG.
The same members as those in the embodiment are designated by the same reference numerals as those in FIGS. As shown in FIGS. 3 and 4, in the second embodiment, the common intake passage 21 has a single surge tank 6 at the downstream end.
It is connected to 0. A branch intake passage 61 for each cylinder is connected to the surge tank 60, and the first intake port 3 and the second intake port 4 are connected to the downstream ends of the branch intake passage 61. In other words, the first intake port 3 and the second intake port 4 are merged on the upstream side, and this merged portion serves as the branch intake passage 61.

The expansion chamber 32 is arranged adjacent to the upper surfaces of the branch intake passages 61, and a communication hole 38 (communication portion) is formed which connects the expansion chamber 32 and each branch intake passage 61. The communication hole 38 is opened and closed by a communication portion opening / closing valve 37 (VICS valve 37). Further, since the surge tank 60 is single, the second relief passage 36 as in the first embodiment is not provided. Other configurations are similar to those of the first embodiment.

In such a structure, the S valve 28 and the VIC
The S valve 37 is controlled by the control unit C as follows. As shown in FIG. 10, in the second embodiment, the S valve 28 is closed in the region where the engine speed is N ₁ or lower and is opened in the region where the engine speed exceeds N ₁ . On the other hand, VIC
S valve 37 is 'full closed in the following areas, N _1' predetermined value N ₁ to the engine rotational speed is set to a low rotation side than the N ₁ to N
Area ₁ is partially opened, and areas above N ₁ are fully opened.

In this case, in the region where the engine speed is N ₁ 'or less, the VICS valve 37 is fully closed, the mixture is supplied from the mixture supply port 7 into the combustion chamber 2, and stratification is promoted. Further, in the region where the engine speed is N ₁ ′ to N ₁ , the S valve 28 is closed while the VICS valve 37 is partially opened, so that the expansion chamber 32 is provided only on the first intake port 3 side.
Inertial supercharging is performed by using the pressure reversal portion as a pressure reversal portion, and intake charging efficiency is enhanced. In the region where the engine speed exceeds N ₁ , the S valve 28 is opened and the VICS valve 37 is fully opened. Therefore, the inertial overpressure which uses the expansion chamber 32 as a pressure reversal portion on the first and second intake ports 3 and 4 side. Supply is performed, and the intake charging efficiency is increased.

In FIG. 10, a curve G ₁₀ shows the characteristic of the engine output torque with respect to the engine speed when such control is performed, and a curve G ₁₁ shows inertia supercharging using the expansion chamber 32 as a pressure reversal section. The output torque when there is not is shown. As is apparent from FIG. 10, when inertial supercharging is performed using the expansion chamber 32 as the pressure reversal unit, the engine output torque is increased in the region where the engine speed exceeds N ₁ ′. In particular, in the region where the engine speed exceeds N ₁ , unlike the case of the first embodiment, inertial supercharging is performed on both intake port sides, so the intake charging efficiency is further enhanced.
Thus, according to the second embodiment as well, the ignitability and combustibility of the air-fuel mixture can be improved in the low rotation speed region, and the intake charging efficiency can be increased in the high rotation speed region.

[0049]

According to the first aspect of the invention, in the low rotation speed region, the pulsation of the pressurized air supplied to the air-fuel mixture supply port is attenuated in the expansion chamber, so that the air-fuel mixture supply port enters the combustion chamber. The flow velocity (flow rate) of the inflowing air-fuel mixture is made uniform, the stratification of the air-fuel mixture in the combustion chamber is stabilized, and the ignitability of the air-fuel mixture
Combustibility is enhanced. On the other hand, in the high engine speed region, inertial supercharging is performed in the intake port by using the expansion chamber as a pressure reversal unit, so that intake charging efficiency is increased and engine output is increased. In this case, since the pressure wave propagation path length from the expansion chamber to the downstream end of the intake port is relatively short, the tuned natural frequency in inertia supercharging is high, and thus the effect of inertia supercharging in the high rotation region is enhanced. .

According to the second invention, basically, the same operation and effect as those of the first invention can be obtained. Further, since the first intake port is used as the swirl generation port, the air-fuel mixture can be supplied from the air-fuel mixture supply port into the combustion chamber while strengthening the swirl in the low rotation speed region. Stratification can be further promoted, and the ignitability and combustion chamber can be further enhanced.

According to the third invention, basically, the same operation and effect as those of the first invention can be obtained. Further, since the communication part communicates the expansion chamber with the confluence part of both intake ports, the effect of inertial supercharging in the high rotation region is further enhanced. Also, in the area where the swirl control valve is closed, the communication part opening / closing valve is partially opened, so excess air on the air-fuel mixture supply port side is relieved to the intake port side, and air is supplied to the air-fuel mixture supply port. The amount is stabilized and optimized, and stratification of the air-fuel mixture is further promoted and stabilized. In addition, in the region where the swirl control valve is opened, the communication part opening / closing valve is fully opened, so that the intake charging efficiency is further enhanced.

According to the fourth invention, basically, the same operation and effect as any one of the first to third inventions can be obtained. Further, since the fuel supply to the air-fuel mixture supply port is stopped in the high load / high speed region, the air-fuel mixture in the combustion chamber is homogenized and uniform combustion is performed in the high load / high speed region, resulting in engine output. To be enhanced.

According to the fifth invention, basically, the same action and effect as any one of the first to third inventions can be obtained. Furthermore, since the Mach coefficient at the air-fuel mixture supply port is 0.4 or more in the entire operating region, the flow rate (flow velocity) of the air flowing from the air-fuel mixture supply port into the combustion chamber per unit time is almost irrespective of the engine speed. It will be constant. Therefore, the distribution position of the air-fuel mixture flowing into the combustion chamber from the air-fuel mixture supply port is made uniform, the stratification is stabilized, and the ignitability and combustibility are further enhanced. Further, since the Mach coefficient in the intake port is less than 0.4 in all regions, the air flow rate per unit time increases as the engine speed increases, and the engine output controllability becomes good.

According to the sixth invention, basically, the same operation and effect as those of the first invention can be obtained. Further, since the pressurized air is relieved to the side of the first intake port, the pressurized air enhances the intake charging efficiency, and the swirl is strengthened to enhance the ignitability / combustibility of the air-fuel mixture.

According to the seventh invention, basically the same action and effect as the first invention can be obtained. Further, in the region where the swirl control valve is closed, the pressurized air is relieved to the first intake port side via the second relief passage, and the pressurized air enhances the intake charging efficiency, and
The swirl is strengthened and the ignitability and combustibility of the air-fuel mixture is enhanced. Further, in the region where the swirl control valve is opened, the pressurized air is relieved to both intake port sides through the first relief passage, and the pressurized air enhances the intake charging efficiency.

According to the eighth aspect of the invention, in the low rotation speed region, the pulsation of the air supplied to the air-fuel mixture supply port is attenuated in the expansion chamber, so the flow velocity of the air-fuel mixture flowing from the air-fuel mixture supply port into the combustion chamber. The (flow rate) is made uniform, the stratification of the air-fuel mixture in the combustion chamber is stabilized, and the ignitability and combustibility of the air-fuel mixture are enhanced. On the other hand, in the high rotation speed region, inertia supercharging is performed using the expansion chamber as a pressure reversal unit, so that intake charge efficiency is increased and engine output is increased. Further, since the first intake port is the swirl generation port, the mixture can be supplied from the mixture supply port into the combustion chamber while the swirl is strengthened in the low rotation speed region, and the mixture in the combustion chamber Stratification can be further promoted, and ignitability and combustibility can be further enhanced. Furthermore, since the pressure wave propagation path length from the expansion chamber to the downstream end of the second intake port is relatively short, the tuned natural frequency in inertia supercharging is high, which increases the effect of inertia supercharging in the high rotation region. To be

According to the ninth invention, basically, the same action and effect as the eighth invention can be obtained. Furthermore, since the Mach coefficient at the air-fuel mixture supply port is 0.4 or more in the entire operating region, the flow rate (flow velocity) of the air flowing from the air-fuel mixture supply port into the combustion chamber per unit time is almost irrespective of the engine speed. It will be constant. Therefore, the distribution position of the air-fuel mixture flowing into the combustion chamber from the air-fuel mixture supply port is made uniform, the stratification is stabilized, and the ignitability and combustibility are further enhanced. Further, since the Mach coefficient in the intake port is less than 0.4 in all regions, the air flow rate per unit time increases as the engine speed increases, and the engine output controllability becomes good.

According to the tenth invention, basically the same action and effect as those of the eighth invention can be obtained. Further, since the pressurized air is relieved to the side of the first intake port, the pressurized air enhances the intake charging efficiency, and the swirl is strengthened to enhance the ignitability / combustibility of the air-fuel mixture.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an engine showing a first embodiment of the present invention.

2 is a vertical cross-sectional explanatory view of the engine shown in FIG.

FIG. 3 is a system configuration diagram of an engine showing a second embodiment of the present invention.

FIG. 4 is a vertical cross-sectional explanatory view of the engine shown in FIG.

FIG. 5 is a diagram showing characteristics of engine output torque with respect to engine speed in the first embodiment.

FIG. 6 is a diagram showing the characteristics of the charging efficiency with respect to the engine speed when the VICS valve is opened / closed in accordance with the opening / closing of the S valve in the first embodiment.

FIG. 7 is a diagram showing a characteristic of an engine output torque with respect to an engine speed in the first embodiment.

FIG. 8 is a diagram showing the characteristics of the degree of air turbulence with respect to the engine speed in the first embodiment.

FIG. 9 is a diagram showing the characteristics of the air discharge amount of the air pump and the air flow rate flowing into the combustion chamber from the air-fuel mixture supply port with respect to the engine speed in the first embodiment.

FIG. 10 is a diagram showing a characteristic of an engine output torque with respect to an engine speed in a second embodiment.

[Explanation of symbols]

 CE ... Engine C ... Control unit 2 ... Combustion chamber 3, 4 ... First and second intake ports 7 ... Mixture supply port 14 ... Second fuel injection valve 20 ... Mixture supply port opening / closing valve 24, 25 ... First, Second surge tank 28 ... Swirl control valve (S valve) 32 ... Enlargement chamber 33 ... Air pump 34,36 ... First and second relief passages 35 ... Relief switching valve 37 ... Communication part opening / closing valve (VICS valve) 38 ... Communication hole 30 ... Surge tank 61 ... Branch intake passage

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location F02D 41/02 325 G 8011-3G F02M 35/10 102 M 301 P 69/00 360 C 8923-3G (72) Keiji Araki Inventor Keiji Araki 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Motor Corporation

Claims (10)

[Claims] 1. An air-fuel mixture which is open to a combustion chamber and is supplied with pressurized air from a pressurized air supply source and is also supplied with fuel from a fuel supply source to generate an air-fuel mixture with the pressurized air and the fuel. In an intake system of an engine provided with a supply port and a mixture supply port opening / closing valve that opens the opening of the mixture supply port to the combustion chamber for a predetermined period between the latter half of the intake stroke and the first half of the compression stroke, An expansion chamber connected to the upstream part of the supply port, a communication part for communicating the expansion chamber with a midway part of the intake port, and a communication part opening / closing valve for opening and closing the communication part are provided. Is formed so that the intake path length from the expansion chamber to the downstream end of the intake port is shorter than the intake path length from the surge tank to the downstream end of the intake port, and the communication opening / closing valve is opened in a predetermined high rotation region. Become like An intake device for an engine according to claim Rukoto. 2. The intake system for an engine according to claim 1, wherein the intake port includes a first intake port that is a swirl generation port, and a second intake port that includes a swirl control valve that is closed in a predetermined operating region. An intake device for an engine, characterized in that the communication part is formed so as to connect the expansion chamber and the middle part of the second intake port. 3. The engine intake system according to claim 1, wherein the intake port includes a first intake port that is a swirl generation port, and a second intake port that includes a swirl control valve that is closed in a predetermined operating region. And is divided into
The first intake port and the second intake port are merged on the upstream side for each cylinder, the communication portion is formed to communicate the expansion chamber and the merged portion, and the communication passage opening / closing valve is a swirl control valve. An intake system for an engine, characterized in that it is partially opened in a region where the valve is closed and fully opened in a region where the swirl control valve is opened. 4. The engine intake system according to any one of claims 1 to 3, wherein the communication part opening / closing valve is opened in a predetermined high load / high rotation region, and the high load / high An intake system for an engine, wherein fuel supply to an air-fuel mixture supply port is stopped or reduced in a rotation region and fuel supply from an intake port is substantially started. 5. The intake system for an engine according to any one of claims 1 to 3, wherein the air-fuel mixture supply port is formed so that an average Mach coefficient in a low rotation region is 0.4 or more. In addition, the intake port of the engine is characterized in that the intake port is formed so that the average Mach coefficient in the high rotation speed region is less than 0.4. 6. The engine intake system according to claim 2, further comprising a relief passage for relieving the air pressurized by the pressurized air supply source to the first intake port side. Engine intake device. 7. The intake system for an engine according to claim 2, wherein only a first relief passage for relieving air pressurized by a pressurized air supply source to both intake port sides and a first intake port side. A second relief passage for relief and a relief switching means for switching between relief of the pressurized air to the first relief passage or relief of the second relief passage are provided, and the relief switching means is a swirl control valve. When the valve is opened, the pressurized air is relieved to the first relief passage, and when the swirl control valve is closed, the pressurized air is relieved to the second relief passage. And the intake system of the engine. 8. An air-fuel mixture which is opened to a combustion chamber and is supplied with pressurized air from a pressurized air supply source and is also supplied with fuel from a fuel supply source to generate an air-fuel mixture with the pressurized air and the fuel. In an intake device of an engine provided with a supply port and an air-fuel mixture port opening / closing valve that opens an opening of the air-fuel mixture port to the combustion chamber for a predetermined period between the latter half of the intake stroke and the first half of the compression stroke. Is divided into a first intake port that is a swirl generation port and a second intake port that is equipped with a swirl control valve that is closed in a predetermined operating region, and is an expansion chamber that is connected to an upstream portion of the mixture supply port. And a communication part for communicating the expansion chamber with a middle part of the second intake port, and a communication part opening / closing valve for opening and closing the communication part. The expansion chamber and the communication part are connected to the second intake port from the expansion chamber. port The intake path length to the flow end is formed to be shorter than the intake path length from the surge tank to the downstream end of the second intake port, and the communication opening / closing valve is opened in the operating region where the swirl control valve is opened. The intake system of the engine, which is characterized by 9. The intake system for an engine according to claim 8, wherein the air-fuel mixture supply port is formed so that the average Mach coefficient in the low rotation speed region is 0.4 or more, and the intake port is in the high rotation speed region. Is formed so that the average Mach coefficient in is less than 0.4. 10. The engine intake system according to claim 8, further comprising a relief passage for relieving the air pressurized by the pressurized air supply source to the first intake port side. Engine intake device.