JPH0693941A - Fuel feeding device for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide an engine which performs stratification of air-fuel mixture by using a single fuel injection valve used for one cylinder. CONSTITUTION:A first and a second intake air port, opened to a combustion chamber, of one cylinder are formed in a branched state, and a means is provided to throttle intake air, sucked to the combustion chamber through the second intake air port, at least during low load running. A fuel injection valve 3 is arranged in a position situated upstream from a branch point between the intake ports. A first injection nozzle 21 through which fuel is injected toward the first intake air port and a second injection nozzle 22 through which the fuel is injected toward the second intake air port are formed in a branched state in the fuel injection valve 3. Further, an assist air feed passage 7 through which an intake air passage situated upper stream from a throttle valve is communicated with the first injection nozzle 21 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved fuel supply system for an internal combustion engine.

[0002]

2. Description of the Related Art As a method for obtaining stable combustion even with a lean air-fuel mixture, an appropriate swirl is generated in the combustion chamber and
Stratification of the air-fuel mixture that makes the air-fuel ratio near the spark plug richer than the other is effective.

As a fuel supply device used for a lean burn engine, there is a conventional fuel supply device as shown in, for example, FIG. 9 (see Japanese Patent Laid-Open No. 61-91619).

Explaining this, a first intake port 41 having a helical shape and a second intake port 42 having a straight shape opening into the combustion chamber 40 of one cylinder are branched. A first fuel injection valve 51 and a second fuel injection valve 52 are arranged in the middle of the intake ports 41, 42, respectively.

A swirl control valve 43 is provided in the middle of the second intake port 42, and the swirl control valve 43 throttles the intake flow drawn into the combustion chamber 40 from the second intake port 41 under a predetermined operating condition. The swirl is generated in the combustion chamber 40 by strengthening the force of the intake flow sucked into the combustion chamber 40 from the second intake port 42.

Under an operating condition in which the swirl is generated in the combustion chamber 40 by the intake air flow flowing from the first intake port 41, the fuel injection amount of the second fuel injection valve 52 is made larger than that of the first fuel injection valve 51, The air-fuel mixture, which is richer than the first air-intake port 41, flows into the central region of the combustion chamber 40 from the intake port 42, and the air-fuel mixture is stratified.

Under operating conditions in which the swirl control valve 43 is opened and intake air is evenly taken in through the intake ports 41, 42, the first fuel injection valve 51 and the second fuel injection valve 52 are provided.
The fuel is evenly injected from.

[0008]

However, in such a conventional fuel supply device for an internal combustion engine, the first fuel injection valve 51 and the second fuel injection valve 52 are provided in the middle of the intake ports 41, 42. Due to the structure provided respectively, there is a problem that the number of fuel injection valves increases and the cost increases.

Further, Japanese Utility Model Laid-Open No. 2-141678 proposes a structure in which the direction of fuel spray from the fuel injection valve is bent by using assist air. However, in an engine having two intake ports, fuel spray from the fuel injection valve is proposed. Are preferably injected toward the center of each intake port, and when the fuel spray direction is bent by the assist air, there is a problem that a wall flow of fuel and the like occur.

In view of the above problems, the present invention has an object to provide an engine for stratifying the air-fuel mixture by using a single fuel injection valve for one cylinder.

[0011]

SUMMARY OF THE INVENTION According to the present invention, a first intake port and a second intake port opening in a combustion chamber of one cylinder are formed in a branched manner, and the intake air is sucked into the combustion chamber through the second intake port. A means for restricting the flow at least when the load is low is provided, a fuel injection valve is provided upstream from the branch point of each intake port, and the first injection hole and the second intake air which inject fuel into the fuel injection valve toward the first intake port A second injection hole that injects fuel toward the port is formed in a branched manner, and an assist air supply passage that connects the intake passage upstream of the throttle valve and the first injection hole is provided.

[0012]

[Function] Under operating conditions in which the intake flow is not throttled by the throttle valve, the differential pressure does not develop upstream and downstream of the throttle valve, so no intake flow occurs in the assist air supply passage. The fuel is evenly injected from.

Under operating conditions in which the intake air flow drawn into the combustion chamber through the second intake port is throttled, the intake air flowing into the first injection hole through the assist air supply passage as the throttle valve is closed is closed. Flow occurs. For this reason, the amount of fuel ejected from the first injection hole becomes smaller than the amount of fuel ejected from the second injection hole as the intake flow flowing into the first injection port increases. The lean air-fuel mixture sucked through the first intake port causes swirl in the combustion chamber and the second intake port through the second intake port by restricting the intake air flow that is sucked into the combustion chamber through the second intake port. The rich air-fuel mixture that is sucked in flows into the central region of the combustion chamber, and stratification of the air-fuel mixture that makes the air-fuel ratio near the spark plug richer than the other is performed.

As the intake air flow rate flowing into the first injection hole through the assist air supply passage increases, the ratio of the fuel amount ejected from the first injection hole and the second injection hole changes. The spray direction of the fuel ejected from the holes and the second injection holes does not change, and the wall flow of the fuel can be prevented from occurring.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings.

As shown in FIGS. 2 and 3, the intake passage 1 is formed with a first intake port 11 and a second intake port 12 that branch into the combustion chamber 5 of one cylinder. First intake port 1
The first and second intake ports 12 are straight and symmetrically formed. A spark plug 6 is arranged at the center of the combustion chamber 5.

A throttle valve 2 is provided in the middle of the intake passage 1, and the throttle valve 2 adjusts the intake amount by interlocking with an accelerator pedal.

A swirl control valve 4 is provided upstream of the branch point 13 of each intake port 11, 12 as a means for restricting the intake flow introduced into the combustion chamber 5 through the second intake port 12 when the load is low. The swirl control valve 4 has a notch 4a that is offset from the center of the flow path of the intake passage 1 and opens. Most of the notch 4a opens facing the first intake port 11, and most of the intake air passing through the notch 4a when the swirl control valve 4 is closed is guided to the first intake port 11, and the remaining part of the notch 4a remains. A part of the swirl is introduced to the second intake port 12 and swirls in the combustion chamber 5 due to the intake flow flowing from the second intake port 11.

The swirl control valve 4 has a rotating shaft 8 connected to an actuator (not shown). The actuator controls the control device to close the swirl control valve 4 when the engine load is low and open the swirl control valve 4 when the engine load is medium or high.

A fuel injection valve 3 is provided in the middle of the intake passage 1. The fuel injection valve 3 is a branch point 1 of each air port 11 and 12.
It is arranged on the upstream side of 3 and immediately upstream of the swirl control valve 4.

As shown in FIG. 1, the fuel injection valve 3 includes a first injection hole 21 for injecting fuel toward the first intake port 11,
Second injection hole 2 for injecting fuel toward the second intake port 12
2 and. The first injection hole 21 and the second injection hole 22 are branched and formed in a V shape in the nozzle body 20, and the fuel spray injected from the first injection hole 21 and the second injection hole 22 is shown by a two-dot chain line in FIG. Thus, the flow is divided into the first intake port 11 and the second intake port 12. Even when the swirl control valve 4 is closed, the first injection hole 21 and the second injection hole 22
Most of the fuel spray injected from the first intake port 11 and the second intake port 12 passes through the notches 4a.
The atomization of the fuel can be promoted by colliding a part of the fuel spray with the swirl control valve 4.

The fuel injection valve 3 includes a valve body that opens and closes a fuel passage communicating with the first injection hole 21 and the second injection hole 22, and a coil that drives the valve body in the valve opening direction. Fuel having a constant differential pressure with respect to the intake pipe pressure is supplied to the fuel passage via a pressure regulator. A pulse current according to the load of the engine is sent to the coil, the valve opening ratio of the valve element is duty-controlled, and the first injection hole 11 and the second injection hole 22 are provided.
The amount of fuel sprayed from is adjusted.

An assist air supply passage 7 that connects the first injection hole 21 of the fuel injection valve 3 and the intake passage 1 upstream of the throttle valve 2 is provided. Due to the pressure difference generated before and after the throttle valve 2, it is ejected to the first injection hole 21 through the assist air supply passage 7.

The assist air supply passage 7 is formed by an annular space 23 defined between the nozzle body 20 of the fuel injection valve 3 and the casing 19, and an orifice 24 connecting the annular space 23 and the first injection hole 21. To be done. The opening diameter of the orifice 24 determines the amount of air ejected from the assist air supply passage 7 to the first injection hole 21.

The orifice 24 is formed orthogonally to the first injection hole 21 and faces the inner wall 21a downstream of the branch point between the first injection hole 21 and the second injection hole 22.

Next, the operation will be described.

As shown in FIG. 4, the flow rate of fuel injected from the first injection port 21 decreases in accordance with the negative pressure generated on the downstream side of the throttle valve 2. By arbitrarily forming the opening diameter of the office 24, the fuel injection amount from the first injection port 21 can be set appropriately. Further, as the opening degree of the throttle valve 2 increases, the differential pressure across the throttle valve 2 decreases, so that the assist air supply passage 7
The amount of intake air that passes through is reduced. Therefore, the supply of assist air can be controlled according to the opening of the throttle valve 2 without providing an opening / closing valve or the like in the assist air supply passage 7.

Under an operating condition in which the swirl control valve 4 is opened so that the intake air flow that is drawn into the combustion chamber 5 through the second intake port 12 is not throttled, the throttle valve 2 is close to fully open, so the assist air supply passage 7 is opened. There is no flow of intake air flowing through and into the first injection hole 21, and the fuel is evenly injected from the first injection hole 21 and the second injection hole 22.

Under operating conditions in which the intake flow drawn into the combustion chamber 5 through the second intake port 12 is throttled, the assist air supply passage 7 is accompanied by the closing of the throttle valve 2.
The amount of fuel ejected from the first injection hole 21 is increased as the amount of intake air flowing through the first injection hole 21 increases and the flow rate of intake air in the first injection hole 21 increases. Less. As a result, the air-fuel ratio of the intake air introduced from the second intake port 12 is
It becomes thicker than the intake air derived from.

The lean air-fuel mixture sucked through the first intake port 11 causes swirl in the combustion chamber by restricting the intake air flow sucked into the combustion chamber 4 through the second intake port 12. The rich air-fuel mixture sucked through the second intake port 12 flows toward the central region of the combustion chamber 5, and stratification of the air-fuel mixture that makes the air-fuel ratio near the spark plug 6 richer than the others is performed. .

As shown in FIG. 5, the swirl generated in the combustion chamber 5 by the intake flow introduced from the first intake port 11 as the piston descends revolves around the axis O inclined with respect to the cylinder. In the vicinity of this axis O, a region where the gas flow is small occurs. Since the axis O is located in the vicinity of the second intake port 12, the second intake port 12 opens toward the region where the swirl is weak, and the intake flow introduced from the second intake port 12 is It flows into the combustion chamber 5 so as to be sucked into the central part of the swirl. Second intake port 1
The air-fuel mixture flowing from 2 into the center of the swirl is collected near the spark plug 6 located in the center of the combustion chamber 5 as the piston moves up.

Even if the ratio of the amount of fuel ejected from the first injection hole 21 and the second injection hole 22 changes due to the flow of intake air flowing into the first injection hole 21 through the assist air supply passage 7, The spray direction of the fuel ejected from the injection hole 21 and the second injection hole 22 does not change, and a large amount of fuel adheres to the wall surface of the intake passage 1 to increase the emission amount of unburned HC and to improve the transient response. It can prevent the deterioration.

Next, in another embodiment shown in FIGS. 6, 7, and 8, the first injection hole 21 and the second injection hole 22 of the fuel injection valve 3 are used.
And assist air supply passages 7 and 27 that connect the intake passage 1 on the upstream side of the throttle valve 2 respectively.

An on-off valve 29, which is controlled to open and close according to operating conditions, is provided in the middle of the assist air supply passage 27 communicating with the second injection hole 22.

An annular space 23 defined between the nozzle body 20 of the fuel injection valve 3 and the casing 19 is defined,
The annular space 23 is partitioned into two spaces 23a and 23b by a pair of sealing materials 31. Each space 23a and 2
Orifices 24 and 28 are formed to connect 3b to the first injection hole 21 and the second injection hole 22, respectively.

The orifices 24 and 28 are orthogonal to the first injection hole 21 and the second injection hole 22, and the first injection hole 21 and the second injection hole 2 are formed.
The inner walls 21a and 22a on the downstream side of the bifurcation point are opposed to each other.

In this case, the opening / closing valve 31 opens the assist air supply passage 27 and the swirl control valve 4 at the time of cold start. As a result, a part of the intake air is ejected through the assist air supply passages 7 and 27 into the first injection hole 21 and the second injection hole 22, respectively, and atomization of the fuel spray is promoted to improve the startability. At the same time, the emission of unburned HC can be reduced.

After warming up, the on-off valve 31 closes the assist air supply passage 27 and closes the swirl control valve 4 when the load is low to generate swirl in the combustion chamber and to supply the assist air, as in the previous embodiment. The air-fuel mixture is stratified by the intake air flow introduced from the passage 7, and the combustion by the lean air-fuel mixture is stabilized.

As a means for restricting the intake air flow introduced into the combustion chamber 5 through the second intake port 12 when the load is low, the lift amount of the intake valve that opens and closes the second intake port 12 according to operating conditions is A variable valve lift mechanism may be provided to reduce the lift amount of the intake valve that opens and closes the intake port 11.

[0040]

As described above, according to the present invention, the first intake port and the second intake port opening to the combustion chamber of one cylinder are formed in a branched manner, and the first intake port and the second intake port are sucked into the combustion chamber through the second intake port. A means for restricting the intake air flow is provided at least when the load is low, a fuel injection valve is provided upstream from the branch point of each intake port, and a first injection hole and a second injection hole for injecting fuel toward the first intake port are provided in the fuel injection valve. A swirl is generated in the combustion chamber because the second injection hole for injecting fuel toward the intake port is branched and the assist air supply passage that connects the intake passage on the upstream side of the throttle valve and the first injection hole is provided. Accordingly, the ratio of the fuel injection amount to each intake port can be changed, and stable lean combustion due to stratification of the air-fuel mixture can be realized.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a fuel injection valve showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of an intake passage of the same.

FIG. 3 is a configuration diagram of an intake passage and a combustion chamber of the same.

FIG. 4 is a diagram showing a relationship between a fuel injection amount from the first injection port and a suction negative pressure.

FIG. 5 is a diagram showing a state of intake air flow in the combustion chamber.

FIG. 6 is a vertical sectional view of a fuel injection valve showing another embodiment.

FIG. 7 is a cross-sectional view of a fuel injection valve of the same.

FIG. 8 is a configuration diagram of an intake passage of the same.

FIG. 9 is a configuration diagram of an intake passage and a combustion chamber showing a conventional example.

[Explanation of symbols]

 1 intake passage 2 throttle valve 3 fuel injection valve 4 swirl control valve 5 combustion chamber 6 spark plug 7 assist air supply passage 11 first intake port 12 second intake port 21 first injection hole 22 second injection hole

Claims (1)

[Claims] 1. A means for branching and forming a first intake port and a second intake port opening to a combustion chamber of one cylinder, and restricting an intake flow drawn into the combustion chamber through the second intake port at least at a low load. A fuel injection valve is provided upstream of the branch point of each intake port, and the fuel injection valve injects fuel toward the first intake port and the second injection port. A fuel supply device for an internal combustion engine, characterized in that a second injection hole is formed in a branched manner, and an assist air supply passage that connects the intake passage upstream of the throttle valve and the first injection hole is provided.