JP2004176561A - Fuel control device for multi-cylinder internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel control device for a multi-cylinder internal combustion engine capable of equalizing air-fuel ratios between cylinders even though operating conditions are changed. <P>SOLUTION: Gaseous fuel supplied to a mixer 3 through a fuel supply pipe 4 fills an annular fuel chamber 14, is supplied from the pair of fuel supply openings 13 of an annular member 11 into an intake air passage 10, and sucked into two or more air cylinders of an gas engine as a fuel/air mixture. The operating conditions of the gas engine are grasped based on the engine speed N of the gas engine detected by an engine speed sensor and intake air pressure P in an intake pipe 2 detected by a pressure sensor, the annular member 11 is rotated by a motor 5 so that the air-fuel ratios between two or more air cylinders of the gas engine are equalized according to the operating conditions of the gas engine, and the positions of the pair of fuel supply openings 13 to the intake air passage 10 are moved and controlled. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel control device for a multi-cylinder internal combustion engine, and more particularly to equalizing the air-fuel ratio of each cylinder.
[0002]
[Prior art]
The air-fuel ratio of each cylinder in a multi-cylinder internal combustion engine in which a carburetor and a mixer are arranged in an intake air passage is preferably equalized among the cylinders, but the shape of the intake air passage, the arrangement position of the carburetor and the mixer, and the like are preferable. May be uneven due to the If the air-fuel ratio between the cylinders becomes uneven, NOx, CO, etc. in the exhaust gas will increase and fuel efficiency will deteriorate. In particular, in the case of an internal combustion engine that performs lean combustion, the lean combustion limit is reduced due to the uneven air-fuel ratio, and the original purpose of lean combustion such as reduction of NOx and CO and low fuel consumption cannot be achieved. . In addition, if the air-fuel ratio is not uniform, the combustion temperature of a specific cylinder rises, causing a difference in the form of valve seat wear between cylinders.Therefore, it is necessary to take measures such as adopting a material with high hardness as the material of the valve seat. , Which leads to higher costs.
[0003]
Therefore, as disclosed in Patent Document 1, for example, a technique has been proposed in which an air-fuel ratio of each cylinder is equalized by devising the shape of an intake manifold forming an intake system of an internal combustion engine.
[0004]
[Patent Document 1]
JP-A-7-208285
[Problems to be solved by the invention]
However, it is known that the non-uniform air-fuel ratio between the cylinders is also caused by the intake air amount and the throttle opening, and even if the shape of the intake manifold is devised as in Patent Document 1, the internal combustion engine is not There is a problem that the air-fuel ratio becomes uneven when the operating conditions change.
The present invention has been made in order to solve such a problem, and provides a fuel control device for a multi-cylinder internal combustion engine that can equalize the air-fuel ratio between cylinders even when operating conditions change. With the goal.
[0006]
[Means for Solving the Problems]
A fuel control device for a multi-cylinder internal combustion engine according to the present invention is provided with operating state detecting means for detecting an operating state of the multi-cylinder internal combustion engine, and movably disposed in an intake air passage connected to the multi-cylinder internal combustion engine. A mixer having a fuel supply port and supplying fuel into the intake air passage from the fuel supply port to generate an air-fuel mixture; a driving means for moving the fuel supply port of the mixer; and an operating state detection means. Control means for moving the fuel supply port of the mixer by the driving means so that the air-fuel ratio between the cylinders of the multi-cylinder internal combustion engine becomes equal based on the operating state of the multi-cylinder internal combustion engine. The fuel supply port of the mixer is moved by the driving means in accordance with the operating state of the multi-cylinder internal combustion engine detected by the operating state detecting means, whereby the air-fuel ratio between the cylinders of the multi-cylinder internal combustion engine is equalized.
[0007]
The mixer includes a mixer main body having a tubular intake air passage formed therein, an annular member forming a part of a pipe wall of the intake air passage and having a pair of fuel supply ports opposed to each other formed therein, and a mixer main body. And a guide supporting portion formed and rotatably supporting the annular member around its central axis. As the annular member supported by the guide support rotates, the position of the fuel supply port relative to the intake air passage moves.
Further, as the driving means, a motor or a negative pressure actuator for driving the annular member to rotate can be used.
Further, the operating state detecting means includes a rotational speed sensor for detecting the rotational speed of the multi-cylinder internal combustion engine, a pressure sensor for detecting the pressure in the intake air passage, an air flow meter for detecting the air flow rate in the intake air passage, or an intake air And a throttle sensor for detecting the opening of a throttle valve provided in the passage.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows an overall configuration of a fuel control apparatus according to an embodiment of the present invention applied to a gas engine. An intake pipe 2 is connected to each cylinder of the multi-cylinder gas engine 1, and a mixer 3 is provided in the intake pipe 2. A gas fuel source (not shown) is connected to the mixer 3 via a fuel supply pipe 4. Further, the mixer 3 has a built-in annular member having a fuel supply port to be described later and a motor 5 for rotating the annular member. Further, the gas engine 1 is provided with a rotation speed sensor 6 for detecting the rotation speed N and a pressure sensor 7 for detecting the intake pressure P in the intake pipe 2. An ECU (engine control unit) 8 is connected to the pressure sensor 7.
[0009]
FIG. 2 shows the internal structure of the mixer 3. The mixer 3 includes a mixer main body 9 in which a tubular intake air passage 10 connected to the intake pipe 2 is formed, and an annular member 11 is disposed on the intake air passage 10 in the mixer main body 9. The annular member 11 forms a part of a pipe wall of the intake air passage 10 and has an inner peripheral surface forming a venturi 12, and a pair of fuel supply ports 13 facing each other is opened in the inner peripheral surface. In the mixer main body 9, an annular fuel chamber 14 is formed around the outer periphery of the annular member 11, and the fuel supply pipe 4 is connected to the fuel chamber 14.
[0010]
In addition, annular convex portions 15 are formed on both surfaces of the annular member 11 facing in the axial direction, and these convex portions 15 are loosely fitted to guide support portions 16 formed of an annular groove formed in the mixer body 9. Have been. Further, the annular member 11 has a semi-circular disk portion 17 protruding sideways and having a large number of teeth arrayed on the outer edge thereof, and the teeth of the disk portion 17 serve as the drive shaft of the motor 5. And meshes with a gear 18 attached to the gear.
Further, a throttle valve 19 is disposed downstream of the venturi 12 inside the intake air passage 10 of the mixer body 9.
[0011]
As shown in FIG. 3, the semicircular disk portion 17 of the annular member 11 is formed concentrically with the annular convex portion 15, and the gear 5 and the disk portion 17 are formed by driving the motor 5. The annular member 11 is rotated around its central axis, so that the positions of the pair of fuel supply ports 13 facing each other are also rotated.
[0012]
Next, the operation of the fuel control device according to this embodiment will be described. When gas fuel is supplied from a gas fuel source (not shown) to the mixer 3 through the fuel supply pipe 4, the gas fuel first fills the annular fuel chamber 14, and the intake air flows through the pair of fuel supply ports 13 of the annular member 11. It is supplied into the passage 10. This gas fuel is mixed with air introduced into the mixer 3 via the intake pipe 2 to form an air-fuel mixture, and is drawn into a plurality of cylinders of the gas engine 1 through the plurality of branched intake pipes 2, whereby the gas The engine 1 is driven to rotate.
[0013]
At this time, the rotational speed N of the gas engine 1 is detected by the rotational speed sensor 6 and the intake pressure P in the intake pipe 2 is detected by the pressure sensor 7 and input to the ECU 8. The ECU 8 grasps the operating state of the gas engine 1 from the rotational speed N and the intake pressure P, and according to the operating state, controls the annular member 11 by the motor 5 so that the air-fuel ratio among the plurality of cylinders of the gas engine 1 becomes equal. Is rotated to control the movement of the position of the pair of fuel supply ports 13 with respect to the intake air passage 10.
[0014]
Specifically, for example, as shown in FIG. 4, the position α, the rotational speed N3, and the intake pressure P3 under the operating conditions of the rotational speed N1 and the intake pressure P2 are obtained under the operating conditions of the rotational speed N1 and the intake pressure P1. In the operating conditions, the position of the fuel supply port 13 at which the air-fuel ratio between the plurality of cylinders is the most uniform under the respective operating conditions of the rotational speed N and the intake pressure P such as the position γ. The optimal position of the fuel supply port 13 is read out according to the rotational speed N and the intake pressure P detected by the rotational speed sensor 6 and the pressure sensor 7, and the annular member 11 is rotated by driving the motor 5. .
[0015]
The gas fuel is supplied in a radial direction from the fuel supply port 13 opened in the inner peripheral surface of the annular member 11 into the intake air passage 10, and mixed with air taken in from the upstream side in the intake air passage 10. Therefore, the air-fuel ratio of the air-fuel mixture generated here has an uneven distribution according to the circumferential position of the fuel supply port 13 in the intake air passage 10. This uneven air-fuel ratio distribution causes a plurality of air-fuel ratio distributions that move in the circumferential direction in the intake air passage 10 in response to the rotation of the annular member 11 in which the fuel supply port 13 is formed, and branch off downstream of the mixer 3. This will affect the air-fuel ratio of the air-fuel mixture flowing into each of the intake pipes 2. Therefore, by adjusting the air-fuel ratio distribution of the air-fuel mixture in the mixer 3 by rotating the annular member 11, conventionally, the shape of the intake air passage 10, the arrangement positions of the carburetor and the mixer 3, the operating conditions of the gas engine 1, and the like. Thus, the air-fuel ratio inequality of the air-fuel mixture in the plurality of intake pipes 2 caused by the air-fuel ratio can be canceled, and the air-fuel ratio can be equalized.
[0016]
FIG. 5 shows the excess air ratio of each cylinder when the fuel control device of this embodiment is applied to the four-cylinder gas engine 1 and operated under the conditions of a rotation speed of 2200 rpm and an intake pressure of −20 kPa. For comparison, FIG. 5 also shows the excess air ratio of each cylinder when a conventional mixer in which the position of the fuel supply port cannot be moved is used. Compared with the conventional product in which a large variation in the excess air ratio λ between the cylinders is used, the use of the fuel control device of the present embodiment significantly reduces the variation in the excess air ratio λ between the cylinders, and reduces the air-fuel ratio. It can be seen that equalization is favorably performed.
[0017]
Further, as shown in FIG. 6, in the lean combustion in which the excess air ratio λ is high and the fuel is lean, the thermal efficiency is improved, that is, the fuel consumption is reduced, and the NOx generation amount is reduced. If the control device is applied, the air-fuel ratio can be equalized over the entire operation range of the gas engine 1, so that the lean burn limit is improved over a wide rotation speed range, and operation with lower fuel consumption and lower NOx than before can be performed. It becomes possible.
[0018]
In the above embodiment, the annular member 11 of the mixer 3 is rotated by the motor 5, but the annular member 11 may be driven to rotate by using a negative pressure actuator instead of the motor 5.
[0019]
In the above embodiment, the operating state of the gas engine 1 is determined based on the rotational speed N of the gas engine 1 detected by the rotational speed sensor 6 and the intake pressure P in the intake pipe 2 detected by the pressure sensor 7. I understand, but it is not limited to this. For example, as shown in FIG. 7, an air flow meter 20 is provided in the intake pipe 2 instead of the pressure sensor 7, and the air flow rate in the intake pipe 2 detected by the air flow meter 20 and the detection by the rotation speed sensor 6 are performed. The ECU 8 grasps the operating state of the gas engine 1 based on the rotation speed N and rotates the annular member 11 so that the air-fuel ratio among the plurality of cylinders of the gas engine 1 becomes equal according to the operating state. Thus, the position of the fuel supply port 13 can be controlled to move, and the same effect as in the above embodiment can be obtained.
[0020]
As shown in FIG. 8, a throttle sensor 21 is attached in place of the pressure sensor 7, and the opening degree of the throttle valve 19 detected by the throttle sensor 21 and the rotation speed N detected by the rotation speed sensor 6 are determined. The operating state of the gas engine 1 can also be grasped based on this. Also with this configuration, the air-fuel ratio between the cylinders can be equalized by controlling the movement of the position of the fuel supply port 13, and the same effect as in the above embodiment can be obtained.
[0021]
Although the case where the annular member 11 has a pair of fuel supply ports 13 facing each other has been described, the number of the fuel supply ports 13 is not limited to two, and for example, three or more fuel supply ports It may be formed on the member 11.
In the above embodiment, the fuel control is performed for the gas engine 1, but the present invention can be applied to the fuel control of various multi-cylinder internal combustion engines.
[0022]
【The invention's effect】
As described above, according to the present invention, the fuel supply port of the mixer is moved by the drive means based on the operation state of the multi-cylinder internal combustion engine detected by the operation state detection means. The air-fuel ratio between the cylinders can be equalized.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of a fuel control device for a multi-cylinder internal combustion engine according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing an internal structure of a mixer used in the embodiment.
FIG. 3 is a plan view showing an annular member used for the mixer.
FIG. 4 is a view showing a state of movement of a fuel supply port formed in an annular member.
FIG. 5 is a graph showing variations in the excess air ratio between cylinders in the fuel control device according to the present invention and the conventional fuel control device.
FIG. 6 is a graph showing the relationship between the excess air ratio and the thermal efficiency and the NOx generation amount.
FIG. 7 is a diagram showing an overall configuration of a fuel control device for a multi-cylinder internal combustion engine according to another embodiment.
FIG. 8 is a diagram showing an overall configuration of a fuel control device for a multi-cylinder internal combustion engine according to still another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Gas engine, 2 intake pipes, 3 mixers, 4 fuel supply pipes, 5 motors, 6 rotation speed sensors, 7 pressure sensors, 8 ECUs, 9 mixer bodies, 10 intake air passages, 11 annular members, 12 venturis, 13 fuel supply Mouth, 14 fuel chamber, 15 protrusion, 16 guide support, 17 disk, 18 gear, 19 throttle valve, 20 air flow meter, 21 throttle sensor.

Claims (6)

Operating state detecting means for detecting an operating state of the multi-cylinder internal combustion engine,
A mixer having a fuel supply port movably disposed with respect to an intake air passage connected to the multi-cylinder internal combustion engine and supplying fuel from the fuel supply port into the intake air passage to generate a mixture;
Driving means for moving a fuel supply port of the mixer;
Control means for moving the fuel supply port of the mixer by the driving means such that the air-fuel ratio between the cylinders of the multi-cylinder internal combustion engine is equalized based on the operating state of the multi-cylinder internal combustion engine detected by the operating state detection means And a fuel control device for a multi-cylinder internal combustion engine. The mixer,
A mixer body having a tubular intake air passage formed therein,
An annular member forming a part of the pipe wall of the intake air passage and having a pair of fuel supply ports opposed to each other formed;
2. The fuel control device for a multi-cylinder internal combustion engine according to claim 1, further comprising: a guide support formed on the mixer main body and rotatably supporting the annular member around a center axis thereof. The fuel control device for a multi-cylinder internal combustion engine according to claim 1 or 2, wherein the driving means comprises a motor or a negative pressure actuator that rotationally drives the annular member. The multi-cylinder internal combustion engine according to any one of claims 1 to 3, wherein the operating state detecting means includes a rotational speed sensor for detecting a rotational speed of the multi-cylinder internal combustion engine, and a pressure sensor for detecting a pressure in the intake air passage. Fuel control device for a cylinder internal combustion engine. 4. The operation state detection unit according to claim 1, wherein the operation state detection unit includes a rotation speed sensor that detects a rotation speed of the multi-cylinder internal combustion engine, and an air flow meter that detects an air flow rate in the intake air passage. 5. Fuel control device for a multi-cylinder internal combustion engine. 4. The engine according to claim 1, wherein the operating state detecting means includes a rotational speed sensor for detecting a rotational speed of the multi-cylinder internal combustion engine, and a throttle sensor for detecting an opening degree of a throttle valve provided in the intake air passage. A fuel control device for a multi-cylinder internal combustion engine according to any one of the preceding claims.

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