JPH0610804A - Intake air device of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve transient responsiveness, fuel consumption and exhaust purification by suppressing formation of fuel wall flow. CONSTITUTION:An extension pipe 16a is fitted in the injection hole of a first fuel injection valve 16 provided on the first intake air port 12 side to which supply of intake air is suppressed at time of closing a swirl control valve 14, and fuel is injected and supplied from the position where it may not collide with the swirl control valve 14 together with assisting air supplied via an air gallery 23. At the same time, a second fuel injection valve 17 is installed on the other second intake air port 13 side, and the fuel is injected and supplied via the notch 14a of the swirl control valve 14. Consequently, transient responsiveness is improved since wall flow of fuel can be prevented without allowing injected fuel not only from a first fuel injection valve 17 but also from a first fuel injection valve 16 to stick on the swirl control valve 14, and fuel consumption and exhaust purification are improved since mixture of the fuel and air is improved by such action as atomization of fuel by the assisting air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for an internal combustion engine having two intake ports and a fuel injection valve for each cylinder.
In particular, the present invention relates to a technique for preventing the fuel injected from the fuel injection valve from becoming a wall flow.

[0002]

2. Description of the Related Art As a conventional intake system for an internal combustion engine, there are those shown in FIGS. 4 and 5, for example. That is, the fuel injection valve 1 is mounted on the upper wall portion 2a of the intake pipe 2, and the swirl control valve 3 is provided in the intake port 4 for the purpose of strengthening the intake swirl.

The swirl control valve 3 is closed in the low speed and low load region of the engine so that the intake flow velocity increases and the combustion chamber 5 increases.
The combustion efficiency is improved by generating a strong swirl in the inside to improve the mixing efficiency of the fuel and the air, while the opening in the high speed and high load area increases the intake passage area to increase the intake charging efficiency into the combustion chamber 5. It is designed to increase the output and improve the output.

[0004]

In such a conventional fuel supply device for an internal combustion engine, in order to further strengthen the intake swirl in the combustion chamber, the swirl control valve 3 is brought as close to the combustion chamber 5 side as possible. I am wearing it, but in that case,
The fuel injection valve 1 must be mounted upstream of the swirl control valve 3 because there is not enough space to arrange the fuel injection valve 1 downstream of the swirl control valve 3.

On the other hand, considering the intake property when the swirl control valve is in the open state, the fuel injection valve is required to supply fuel to both intake ports.

[0006]

However, when the fuel injection valve is arranged on the upstream side of the swirl control valve, the fuel injection direction of the fuel injection valve is fixed to a certain fixed direction.
When the swirl control valve is closed, a large amount of fuel adheres to the swirl control valve to form a wall flow, increasing the amount of HC emissions, deteriorating drivability due to fuel transport delay, and reducing the air-fuel ratio. Problems such as difficulty in control may occur.

The present invention has been made in view of the above conventional problems, and suppresses the formation of a fuel wall flow due to the adhesion of fuel to a means such as a swirl control valve that limits the supply of intake air, and exhaust gas. An object of the present invention is to provide an intake system for an internal combustion engine, which has improved cleanability and drivability.

[0008]

Therefore, an intake system for an internal combustion engine according to the present invention is provided with a first intake port and a second intake port opening to a common combustion chamber, and intake air from the first intake port to the combustion chamber. Fuel for restricting the supply of air according to the operating state, an extension pipe extending downstream from the injection hole for injecting fuel, and supplying fuel together with assist air toward the first intake port An injection valve and a second fuel injection valve for supplying fuel to the second intake port are provided, and the first fuel injection valve is arranged at a position where fuel injected from the extension pipe does not collide with the intake restriction means. It was set up.

[0009]

With this structure, by attaching the extension pipe to the fuel injection valve that injects fuel with assist air,
Atomization of fuel injected from the extension tube and narrow spray angle can be obtained. As a result, when the engine is in a state where the intake through the first intake port is restricted, such as during low-speed and low-load operation of the engine,
Although the flow of the intake air in the first intake port is relatively slow, the narrow spray angle prevents the fuel from adhering to the wall surface of the first intake port to form a wall flow. Moreover,
The fuel injected into the intake air having such a gentle flow is supplied in a state of being mixed with the assist air, that is, the sufficient mixing property is secured, so that the fuel efficiency, the transient response property, and the exhaust gas purification property are improved.

Further, by providing the first fuel injection valve with the extension pipe, even if the first fuel injection valve is arranged on the upstream side of the intake restriction means, the first intake air does not collide with the intake restriction means. Since the fuel can be supplied to the port, the intake restriction means can be arranged closer to the combustion chamber, and a strong gas flow can be obtained in the combustion chamber. Further, since the fuel is supplied to the second intake port from the second fuel injection valve, it is possible to perform injection in a form different from that of the first fuel injection valve, for example, to widen the spray angle.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show the structure of an intake device for an internal combustion engine according to a first embodiment of the present invention. In the figure, a first intake port 12 and a second intake port 13 are provided for each combustion chamber 11 of each cylinder of the internal combustion engine.

The first intake port 12 and the second intake port
An intake pipe 15 connected to the upstream side of 13 is equipped with a swirl control valve 14 as an intake restriction means.
A notch 14a facing the first intake port 12 is provided above the horizontally arranged support shaft, and when the valve is closed, the notch 14a is provided on the second intake port 13 side. Although sufficient intake air is supplied, the supply of intake air to the first intake port 12 side is restricted.

The upper wall portion 15a of the intake pipe 15 has a first intake port
A first fuel injection valve 16 for injecting and supplying fuel to 12 and a second fuel injection valve 17 for injecting and supplying fuel to the second intake port 13 are mounted. The first fuel injection valve 16 is connected to an injection hole with an extension pipe 16a extending to the downstream side, and a downstream end of the extension pipe 16a penetrates an upper wall of the first intake port 12 on the upstream end side. The swirl control valve 14 in the closed state is opened directly above the swirl control valve 14 so as to supply fuel to the first intake port 12 on the downstream side. Further, an assist air supply mechanism is connected to the first fuel injection valve 16. That is, after the air pressurized by the air pump 21 is adjusted to a constant pressure via the pressure adjusting valve 22, the air gallery 23 is used to adjust the first fuel injection valve of each cylinder.
It is configured to be supplied to the mixing section 16b of 16 and to be ejected from a large number of injection holes provided in the fuel passage wall to be mixed with the fuel.

On the other hand, the second fuel injection valve 17 is a swirl control valve.
Even when 14 is closed, fuel is injected and supplied to the second intake port 13 on the downstream side through the notch 14a. The first fuel injection valve 16 and the second fuel injection valve 17 are
It is driven by an injection control signal from the control unit 18. The control unit 18 includes a rotation speed sensor 24 for detecting the rotation speed of the engine, an air flow meter 25 for detecting the intake air flow rate, and a water temperature sensor 26 for detecting the cooling water temperature.
Etc., and outputs an injection control signal having a pulse width corresponding to the fuel injection amount set based on these detection signals to the first fuel injection valve 16 and the second fuel injection valve 17 for driving. . Here, the fuel injection period may be set commonly to the first fuel injection valve 15 and the second fuel injection valve 16, but at least the injection from the first fuel injection valve 16 to the first intake port 12 is The setting is performed so that the first intake valve 31 mounted on the side of the first intake port 12 is in the open state. Further, if the fuel injection periods of the first fuel injection valve 16 and the second fuel injection valve 17 are independently controlled, it becomes possible to supply the fuel in an optimal state for the operating condition. Further, the control unit 18 also controls the opening and closing of the swirl control valve 14 according to the operating state.

Next, a series of intake control operations according to this embodiment will be described. The swirl control valve 14 is controlled to be closed when the engine is operating at a low speed under a low load. As a result, as described above, the supply of intake air to the first intake port 12 is restricted, while the cutout 14a of the swirl control valve 14 is provided in the second intake port 13.
Since the intake air is supplied with the flow velocity being accelerated through, a strong swirl is generated in the combustion chamber 11.

On the other hand, from the first fuel injection valve 16, the mixing section 16
The fuel mixed with the assist air in a is injected and supplied to the first intake port 12 on the downstream side of the swirl control valve 14 through the extension pipe 16a, and the second fuel injection valve 17 supplies the swirl control valve 14 The second intake port on the downstream side through the notch 14a
Fuel is supplied to 13 by injection. Here, the first fuel injection valve 16
Since the fuel from is injected from directly above the swirl control valve 14 to the downstream side, it is prevented from colliding with the swirl control valve 14 and is prevented from becoming a wall flow due to a large amount of adhesion to the swirl control valve 14. It Further, although the flow of the intake air flowing through the first intake port 12 is weak, the injection angle is narrowed because the injection is performed through the extension pipe 16a, the adhesion to the wall of the first intake port 12 is suppressed, and the wall flow is formed. Is prevented. Further, the fuel is mixed with the assist air and atomized and supplied, so that the mixing property between the fuel supplied to the first intake port 12 and the air is sufficiently maintained, and at the same time, in the combustion chamber 11. The formation of wall flow can also be prevented. Further, the fuel injection period is set to the first intake valve 31.
Is set to the period when the
It is also possible to prevent the air from adhering to the intake valve 31 and forming a wall flow.

On the other hand, the fuel injected from the second fuel injection valve 17 does not adhere to the swirl control valve 14 since it also passes through the notch 14a, and the intake air flowing through the second intake port 13 has a high flow velocity. Therefore, the mixing property of the injected fuel and the air is kept good. If the injection period of the fuel from the second fuel injection valve 17 is also set to the period in which the second intake valve 32 mounted on the second intake port 13 side is opened, the injected fuel will be injected into the second intake valve 32.
Can be prevented, but especially in high-power engines,
At the time of a high load in which an increase in the injection amount is required, the injection period of the first fuel injection valve 16 is restricted for the above reason.
It may be necessary to prolong the injection period of the fuel injection valve 17, in which case the injection periods may overlap when the second intake valve is closed. However, even if the fuel injection period overlaps when the intake valve is closed and fuel adheres to the intake valve, the flow of intake air in the second intake port 13 is always strong, and therefore some adhered fuel vigorously enters the combustion chamber 11. It can be blown off and can prevent wall flow.

As described above, it is possible to prevent the fuel from forming a wall flow and to ensure good mixing of the fuel and air, so that it is possible to ensure transient response and improve combustibility. Fuel economy and exhaust gas purification are also improved. Further, the swirl control valve 14 is opened during high-speed and high-load operation. In this case, both the first intake port 12 and the second intake port 13 are fully opened, and the intake air flow rate is large, so the flow of intake air is sufficiently strong in both ports, and the fuel does not become a wall flow and mixes with air. Exhaust gas purification performance can be maintained satisfactorily while being sufficiently secured and satisfying high output performance.

When the swirl control valve is closed, the intake air is restricted to the intake port (the first intake port 12 in the embodiment) on the side where the intake air supply is restricted in order to prevent wall flow due to fuel adhesion to the swirl control valve. It is possible to stop the fuel supply,
This causes a large difference in the amount of fuel introduced from the intake port (first intake port 12) into the combustion chamber when the swirl control valve 14 is open and when the swirl control valve 14 is closed. Therefore, if the swirl control valve is operated in two positions, open and closed, a transitional step is generated in the property of the air-fuel mixture formed in the combustion chamber, a torque step is generated, and transient response is deteriorated. .

In this respect, according to the present invention, even if the swirl control valve 14 is controlled to be switched between ON and OFF at two positions of open and closed, the first fuel injection valve 16 is concerned with opening and closing of the swirl control valve 14. Instead of injecting fuel, the problem associated with the difference in fuel injection amount can be solved. Therefore,
Since it suffices to switch control of the swirl control valve 14 between ON and OFF, there is no need to control the opening degree with high precision, and thus the production cost can be reduced.

Further, since the flow of the intake air in the second intake port 13 is always strong, the second intake port 13 has the same second flow as in the present embodiment for cost reduction.
Although the assist air supply mechanism can be omitted on the fuel injection valve 17 side, of course, the assist air supply mechanism may also be connected to the second fuel injection valve 17 side in order to promote atomization of the fuel. Good. Further, when there is a spatial margin on the downstream side of the swirl control valve 14, the first fuel injection valve may be mounted on the downstream side.

Further, the intake restriction means is not limited to the one for generating swirl as in the embodiment, but may be a control valve having a notch for forming a tumble, or may be in an operating state. In accordance therewith, the lift amount of the intake valve may be variable (the intake valve may be made smaller). However, the intake restriction means only restricts the supply of intake air and does not stop the supply.

Further, the first fuel injection valve 16 basically supplies fuel continuously, but the first fuel injection valve 16 may be controlled to stop the fuel supply depending on operating conditions such as a so-called fuel cut condition in which a strong engine brake is applied. May be included. Figure 3
The mode which changed a part of said 1st Example is shown. In the figure, the difference from the first embodiment is that the upstream end of the extension pipe 14a is extended to the vicinity of the first intake valve 31, and with this configuration, the fuel injected to the inner wall of the first intake port 12 is injected. Can be further reduced.

[0024]

As described above, according to the present invention, the fuel is prevented from adhering to the intake restricting means, while the intake port provided with the intake restricting means is assisted via the extension pipe. Since the fuel is atomized together with the air and is supplied at a narrow spray angle, the formation of the wall flow at the intake port wall or the intake restricting means is suppressed and the transient response can be improved, and the mixture of the fuel and the air can be improved. In addition to improving fuel efficiency, combustibility is improved, thereby improving fuel efficiency and exhaust gas purification performance.

Further, since the fuel injection valve is provided separately for the intake port where the intake air supply is restricted and the intake port where the intake air supply is not restricted, it is possible to control the injection period and the like independently, so as to optimize the operation according to the operating condition. It is also possible to control the conditions.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of an intake system for an internal combustion engine according to a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing the structure of the intake device and a view taken along the arrow S in FIG.

FIG. 3 is a cross-sectional view showing the structure of an intake device for an internal combustion engine according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view showing the configuration of an intake device for an internal combustion engine according to a conventional example.

FIG. 5 is a vertical cross-sectional view showing the structure of the intake device and a view taken along arrow S in FIG.

[Explanation of symbols]

 11 Combustion chamber 12 First intake port 13 Second intake port 14 Swirl control valve (intake control means) 16 First fuel injection valve 16a Extension pipe 17 Second fuel injection valve 18 Control unit 21 Air pump 22 Pressure adjustment valve 23 Air gallery

Claims (1)

[Claims] 1. A first intake port and a second intake port opening to a common combustion chamber, and intake restriction means for restricting the supply of intake air from the first intake port to the combustion chamber in accordance with an operating state.
An extension pipe extending downstream from the injection hole for injecting fuel,
In addition, a first fuel injection valve that supplies fuel to the first intake port together with assist air and a second fuel injection valve that supplies fuel to the second intake port are provided, and the fuel is injected from the extension pipe. An intake system for an internal combustion engine, wherein the first fuel injection valve is arranged at a position where fuel does not collide with the intake restriction means.