JPH0799131B2 - Air intake system for fuel injection engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an intake system for a fuel injection engine that includes two independent intake passages for each cylinder and a fuel injection valve. is there.

(Prior Art) Conventionally, various intake devices each having two independent intake passages per cylinder have been developed. In this type of device, the first intake passage is opened in the entire operation range and the second intake passage is opened. The intake passage is opened and closed by an on-off valve or the like according to the operating condition. According to such a device, for example, when the intake air amount is small and the engine speed is low and the load is low, the second intake passage is closed and air is supplied only from the first intake passage to increase the intake flow velocity and improve the combustibility. On the other hand, when the speed is high and the load is high, the intake resistance can be reduced and the output can be secured by opening the second intake passage. Further, opening and closing the second intake passage substantially changes the passage area and changes the cycle of the intake pressure oscillation. Therefore, it is possible to utilize this to enhance the inertial effect of intake air over a wide operating range. it can.

Examples of such an intake system equipped with a fuel injection valve include those provided with fuel injection valves in both intake passages as disclosed in Japanese Utility Model Laid-Open No. 167254/1982, or JP-A-54-84128. There is a fuel injection valve provided only in the first intake passage, as seen in Japanese Patent Laid-Open Publication No. 2003-242242. However,
According to the former, two fuel injection valves are required per cylinder, which is disadvantageous in terms of cost. According to the latter, when both intake passages are open, fuel is distributed and supplied to both intake passages. Compared with, mixing of air and fuel in the combustion chamber tends to be insufficient. In addition to such a device, there is a device in which two intake passages are partially merged in the middle and a fuel injection valve is arranged at this merged portion. Compared to the case where the intake passage is independent, the action of increasing the intake flow velocity and the inertial effect of intake are reduced at the time of low speed and low load.

Therefore, there is a demand for supplying fuel from one fuel injection valve to two independent intake passages without merging on the way. In addition to these requirements,
In particular, in an operating range where the intake air amount is small and air is supplied only from the first intake passage, there is a demand to increase the atomization of the fuel sent into the first intake passage and the mixing action with air.

(Object of the Invention) In view of such circumstances, the present invention can supply fuel from one fuel injection valve to both the first and second intake passages that are independent of each other. In particular, in order to maintain the independence of both intake passages, the fuel supply passage is made thin, and at least in the operating range where air is supplied only from the first intake passage, the airflow in the first intake passage is used effectively. The present invention provides an intake system for a fuel injection engine that can improve mixing of fuel and air and atomization of fuel.

(Structure of the Invention) The present invention relates to a first intake passage that supplies air to all cylinders of an engine in the entire operating range of the engine, and a passage closing means that closes the first intake passage in the low operating range to the high speed side. The second air passage for supplying air only in the operating range is provided independently of each other, and at least the first intake passage is shaped to enhance the dynamic effect of intake air in the low speed side operating range when the second intake passage is closed. In the set intake system, one fuel injection valve is arranged between the two intake passages for each cylinder, and a two-pronged shape is formed from the injection port between the injection port of the fuel injection valve and the intake passages. And a tip end is opened in each of the intake passages, and at least the first intake passage-side opening is provided with a thin fuel supply passage obliquely directed toward the downstream side of the intake passage, and at least the second intake passage is formed. Closed In the low speed side operating range, the fuel injection valve is equipped with a control means for performing fuel injection in the intake stroke.
That is, the fuel is fed from one fuel injection valve to both intake passages through a thin fuel feed passage that does not hinder the independence of both intake passages, and at least the second intake passage is closed. In the operating region in which it is operated, fuel is injected into the first intake passage during the intake stroke, which is the time when the airflow is generated, so that the fuel is surely injected into the airflow.

(Embodiment) FIGS. 1 to 3 show an embodiment of the present invention, in which 1 is an engine body, 2 is a plurality of cylinders arranged in the engine body, and 3 is each cylinder 2 The combustion chambers 4 and 4 are intake systems for the engine body 2. In the intake system 4, two independent intake passages 7 and 8 are provided for each cylinder between the surge tank 6 connected to the intake introduction passage 5 and each cylinder 2. The downstream end of 8 is individually opened to the combustion chamber 3, and the openings 7a and 8a thereof are opened and closed by the intake valves 9 and 10, respectively. Of the two intake passages 7 and 8, the first intake passage 7 always supplies the intake air to the combustion chamber 3, and the second intake passage 8 supplies the intake air only in a specific operation range. An opening / closing valve (passage closing means) 11 for opening and closing the passage 8 according to the operating state is provided so that the passage 8 is closed in the low speed operation range. Then, as described below, at least in the low speed range where the on-off valve 11 is closed, the passage shape of the first intake passage 7 (length, length, The cross-sectional area, etc.) is set. Further, an air cleaner 12, an air flow meter 13 and a throttle valve 14 are arranged in the intake air intake passage 5. Reference numeral 15 is an exhaust passage, 16 is an exhaust valve provided at an opening 16a of the exhaust passage 15 to the combustion chamber 3, and 17 is an ignition plug.

Reference numeral 20 denotes a fuel injection valve, which is provided for each cylinder 2 and is arranged substantially in the middle of the intake passages 7 and 8. Intake passage
First and second fuel supply passages 21 and 22 are provided between the fuel supply passages 7 and 8. As is well known, the fuel injection valve 20 has a structure for injecting fuel from an injection port 20a opened and closed by a valve element operated by a solenoid. Then, the injection amount and the injection timing from the fuel injection valve 20 are controlled by a control circuit (control means) 24 using a microcomputer for receiving the detection signal from the air flow meter 13, the crank angle detection signal 23 and the like. It has become.
In the present invention, in particular, the second valve is provided at least by the opening / closing valve 11.
In the operating range where the intake passage 8 is closed, each fuel injection valve
The injection timing of each fuel injection valve 20 is set so that the fuel injection is performed in the intake stroke of the corresponding cylinder 2.

Both of the fuel supply passages 21 and 22 are connected to the injection port 20a of the fuel injection valve 20.
Is divided into two parts and formed in a straight line, and
At least the opening on the first intake passage side is obliquely directed toward the downstream side of the intake passage, and in the illustrated example, both fuel supply passages 21 and 22 extend obliquely toward the downstream side of the intake passage, and the downstream end of each intake passage It opens into passages 7 and 8. In addition, the above fuel supply passage 2
The fuel supply passages 21 and 22 are made considerably thinner than the intake passages 7 and 8 so that air can be sufficiently suppressed from flowing between the intake passages 7 and 8 through the intake passages 1 and 22. The cross-sectional area is 1/5 or less of each intake passage 7, 8 and the fuel injection valve 20
The downstream side of the fuel supply passages 21 and 22 is formed to be slightly thicker than the upstream side so as to correspond to the spread of the fuel injected from. The on-off valve 11 and the second valve in the second intake passage 8
As for the positional relationship with the downstream end opening of the fuel supply passage 22,
The on-off valve 11 may be arranged downstream of the opening as shown by the solid line in FIG. 3, or may be arranged upstream of the opening as shown by the chain double-dashed line in FIG.

Assist air may be supplied to the nuclear fuel supply passages 21 and 22 in order to promote atomization of fuel and to assist fuel supply. In the embodiment shown in the figure, an assist air passage 26 branched from a passage 25 having an upstream end connected to the intake introduction passage 5 between the air flow meter 13 and the throttle valve 14 is a base of both fuel supply passages 21, 22. It opens at the end-side confluence. Further, in order to improve the mixing of fuel and air in the intake passages 7 and 8, as shown in FIGS. 2 and 3, the fuel supply passages 21 are provided in the intake passages 7 and 8, respectively. It is desirable to dispose mixing plates 27, 28 made of perforated plates so as to face the downstream ends of the plates 22, 22.

FIG. 4 shows an example of a region in which the opening / closing valve 11 is opened and a region in which it is closed. In this example, the engine speed reference value set in advance so as to shift to the lower rotation side as the load increases, On the lower rotation side, the opening / closing valve 11 is closed, and on the higher rotation side, the opening / closing valve 11 is opened. By doing this, when the intake air amount is small and the load is low, the intake air is introduced into the combustion chamber 3 through only the first intake passage 7, so that the intake flow velocity is increased and the intake swirl is generated in the combustion chamber 3. Combustibility is improved, and on the other hand, at the time of high load and high rotation with a large intake amount, intake air is introduced into the combustion chamber 3 through both intake passages 7 and 8, so the intake resistance does not increase, A decrease in intake air charge amount is prevented. Further, due to the propagation of the pressure wave between each cylinder 2 and the surge tank 6, intake pressure vibration occurs in the intake passage for each cylinder, and the frequency of this intake pressure oscillation becomes higher as the cross-sectional area of the intake passage becomes larger. Therefore, by operating the on-off valve 11 as described above, the intake passage cross-sectional area is substantially reduced in the low speed region, and the intake passage cross-sectional area is increased in the high speed region so that the intake pressure oscillations in the low speed region and the high speed region are respectively increased. Matching with the intake valve opening / closing cycle, the inertial effect of intake air is enhanced, and the intake charging efficiency is improved at both low speed and high speed and high load to improve output.
Therefore, the opening / closing control of the opening / closing valve 11 may be performed by closing only in the low speed region with a signal of only the rotation speed, and the specific operation control may be performed by an actuator by a control circuit or the like. Good.

In the intake device configured as described above, the on-off valve
In the operation area on the high speed side where 11 is opened, intake air is supplied to the combustion chamber 3 through both supply passages 7 and 8.
For 7 and 8, fuel is distributed and supplied from one fuel injection valve 20 per cylinder through the fuel supply passages 21 and 22, so that the intake passages 7 and 8 are almost evenly supplied to the combustion chamber 3. An air-fuel mixture in which air and fuel are mixed is supplied, and the concentration of the air-fuel mixture in the combustion chamber 3 is reliably prevented from becoming nonuniform.

On the other hand, in the low speed side operating region where the on-off valve 11 is closed, intake air is supplied to the combustion chamber 3 through the first intake passage 7, but in this case, the fuel supply passages 21 and 22 are formed thin. Since the flow of intake air between both intake passages 7 and 8 is sufficiently suppressed, both intake passages 7 and 8 are kept substantially independent, increasing the intake flow velocity and causing intake swirl. The effect of causing the effect and the effect of increasing the intake inertia effect can be favorably maintained. Further, particularly in this state, since the intake amount and the fuel supply amount are small, if the atomization of the fuel and the mixing with the air are insufficient, the combustion chamber 3
Although the combustibility inside is likely to be unstable, such a situation is prevented by the fuel injection from the fuel injection valve 20 being performed in the intake stroke as described above. That is, since a high-speed airflow is generated in the first intake passage 7 during the intake stroke, if the fuel is sent to the first intake passage 7 at this time, the fuel is quickly mixed into the airflow and mixed, and atomization is promoted. The Rukoto.

Further, as shown by the solid line in FIG. 3, if the opening / closing valve 11 of the second intake passage 8 is provided downstream of the opening position of the fuel supply passage 226, the intake valve is closed when the opening / closing valve 11 is closed. Since the negative pressure generated in the stroke is prevented from acting on the fuel supply passage 22 from the second intake passage 8 side, and the fuel is mainly sucked into the first intake passage 7 side, the fuel is appropriately supplied corresponding to the intake air. Can be deflected. On the other hand, when the opening / closing valve 11 is provided upstream of the opening position of the fuel supply passage 22, the fuel deflecting action as described above is reduced, but the fuel flowing out to the second intake passage 8 is supplied to the opening / closing valve 11. It has the advantages that it does not collect and that it can be easily incorporated into the intake passage.

The specific structure of each part of the device of the present invention can be changed in various ways. For example, the opening / closing valve 11 may allow a small amount of air to circulate without completely closing the second intake passage 8 even in the closed state. In this state, the fuel is supplied to the second intake passage 8 in this state. Even if it enters a little, the fuel can be atomized well and sent to the combustion chamber 3. As a passage closing means for the second intake passage 8, instead of the on-off valve 11, the intake valve 10 on the downstream side of the second intake passage 8 is not operated in a low speed operation range similar to the closing operation range of the on-off valve 11. A mechanism that operates may be adopted.

Further, in the embodiment shown in the drawing, the downstream ends of both intake passages 7 and 8 are individually opened to the combustion chamber 3, and the intake valves 9 and 10 are arranged at the respective opening portions. One intake valve may be shared by both intake passages as long as both intake passages are independently formed up to the position.

Further, the fuel injection valve 20 may be the one used in a general fuel injection type engine, but by making the injection port 20a an elliptical shape or the like, both fuel supply passages 21, 22 can be used. The structure may be such that the particles are dispersed and injected.

(Effects of the Invention) As described above, the present invention provides a thin fuel feed from a fuel injection valve to two independent intake passages, that is, a first intake passage and a second intake passage closed in a low speed operation range. Since the fuel is distributed and supplied through the supply passage, the independence of both intake passages is maintained and the dynamic effect of intake air is not impaired, while one fuel injection valve per cylinder is used for both intake passages. The fuel can be distributed to. Moreover, in particular, at least in the operating range in which the second intake passage is closed, the fuel can be reliably mixed into the air flow by performing the fuel injection in the intake stroke, and the fuel supply passage to the first intake passage is further provided. Mixing with the airflow can be further promoted by directing the opening to the diagonally downstream side. Therefore, the atomization of fuel and the mixing action can be enhanced.

[Brief description of drawings]

FIG. 1 is a schematic plan view of the entire structure showing an embodiment of the device of the present invention, FIG. 2 is an explanatory view of the main parts thereof, FIG. 3 is a sectional view showing the specific structure, and FIG. 4 is a second intake passage. FIG. 3 is an explanatory view showing a region in which the on-off valve provided in the is opened and a region in which the on-off valve is closed. 1 ... Engine body, 2 ... Cylinder, 7,8 ... Intake passage, 2
0 ... Fuel injection valve, 21, 22 ... Fuel supply passage, 24 ... Control circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Hashimoto No. 3 Shinchi Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Akira Kageyama No. 3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Corporation (56) Reference JP-A-57-102516 (JP, A) Actually developed 55-64463 (JP, U)

Claims (1)

[Claims] Claim: What is claimed is: 1. A first intake passage for supplying air to each cylinder of the engine in the entire operating range of the engine, and a passage closing means for closing the operating range on the low speed side to close only in the operating range on the high speed side. An intake device in which a second intake passage adapted to supply air is provided independently of each other, and at least the first intake passage is configured to enhance the dynamic effect of intake air in the low speed operation range when the second intake passage is closed. In this case, one fuel injection valve for each cylinder is disposed between the intake passages, and the intake air extends between the injection port and the intake passages in a bifurcated manner. A low speed fuel supply passage is provided in which a tip is opened in each passage, and at least a first intake passage-side opening is obliquely directed toward a downstream side of the intake passage, and at least a second intake passage is closed. Side operation area Intake device for a fuel injection engine, characterized in that it comprises a control means for causing the intake stroke fuel injection from the fuel injection valve.