JP2004169620A - Fuel injection mechanism for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow change of fuel which is injected corresponding to an operating condition of an engine by using a plurality types of fuels. <P>SOLUTION: The fuel injection mechanism is provided with a first fuel injection nozzle 13 for supplying fuel, a second fuel injection nozzle 14 for supplying a fuel different from the fuel supplied during steady operation of an engine other than the steady operation, and control means for making changeable fuel injection by a fuel injection nozzle. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection mechanism for an engine such as a diesel engine.
[0002]
[Prior art]
In recent years, environmental destruction due to exhaust gas from automobiles, for example, global warming due to CO, NOx, etc. contained in exhaust gas, ozone layer depletion, acid rain, etc., have become problems, and these are causes from the viewpoint of environmental measures. Regulation values of exhaust gas containing CO, NOx, etc., tend to be increasingly strict.
[0003]
For this purpose, various techniques such as improvement of a fuel supply method have been developed, and particularly, a gasoline engine has been improved. On the other hand, there is still room for improvement in diesel engines, such as measures against black smoke.
[0004]
The features of the diesel engine are that the thermal efficiency is higher than that of the gasoline engine, so that the fuel consumption rate can be suppressed, and light oil that is cheaper than gasoline can be used as the fuel.
[0005]
While diesel engines have many of these advantages, they also have disadvantages compared to gasoline engines. For example, light oil used as fuel has a high combustion temperature, so that the amount of NOx emissions increases and the amount of unburned carbon dust increases. That is, since the combustion heat is high, and the calorific value per unit area is large, the hydrocarbons constituting the fuel are decomposed into hydrogen molecules, carbon or methane by a thermal decomposition action, and a large amount of soot, NOx, etc. Will occur.
[0006]
This becomes remarkable when the combustion temperature is relatively low, for example, when starting or starting the diesel engine. In such a state, it is difficult to quickly vaporize the fuel and incomplete combustion is likely to occur, which causes soot and NOx.
[0007]
For this reason, various attempts have been made to assist the above-mentioned disadvantages of the diesel engine while taking advantage of the diesel engine.
[0008]
For example, in Japanese Patent Application Laid-Open No. 2001-193512, in order to have both functions of a gasoline engine and a diesel engine, an engine provided with a fuel injector sharing a gasoline injector and a light oil injector, or an engine provided with each dedicated injector is provided. Is disclosed.
[0009]
[Patent Document 1]
JP 2001-193512 A
[Problems to be solved by the invention]
In the above-mentioned publication, a plurality of kinds of fuels, for example, two kinds of fuels such as gasoline and light oil can be supplied, but how to supply these fuels is not disclosed. That is, a technique for supplying a different type of fuel to assist combustion with only one type of fuel has been known as a known technique. However, according to the above publication, it is not clear whether or not the fuel supply is performed as in the known technique. Further, in the known art, a plurality of fuels, for example, gasoline and light oil are supplied simultaneously while changing the mixing ratio according to the operation state of the engine, and these fuels are separately supplied according to the operation state of the engine. The technology is not clear.
[0011]
The present invention has been made in view of the above points, and has as its object to provide a fuel injection mechanism for an engine in which fuel to be supplied can be switched according to the operating state of the engine.
[0012]
[Means for Solving the Problems]
The invention of an engine fuel injection mechanism according to claim 1, which achieves the above object, comprises a first fuel injection nozzle for injecting fuel during steady operation of the engine, in a fuel injection mechanism of an engine provided with a fuel injection nozzle; A second fuel injection nozzle for injecting a fuel different from the fuel other than during the steady operation; and control means for switching between fuel injection by the first fuel injection nozzle and fuel injection by the second fuel injection nozzle. The control means calculates the operating state of the engine, injects fuel from the first fuel injection nozzle when it is determined that the engine is in a steady operation state, and outputs the first fuel injection when it determines that it is in any other unsteady operating state. The fuel injection system is characterized in that fuel is injected by a second fuel injection nozzle instead of fuel injection by a nozzle.
[0013]
Here, the steady operation refers to an operation state in which the fuel consumption rate is high such that the engine is operated at a low / medium load and a constant rotation speed, and a state in which the exhaust gas generated by the combustion can be as clean as possible is obtained. Means that
[0014]
According to this, different types of fuel are provided with respective fuel injection nozzles, and the fuel injection by these fuel injection nozzles can be switched, so that the fuel can be accurately injected according to the operating condition of the engine. In addition, the exhaust gas of an automobile engine, particularly a diesel engine, can be cleaned.
[0015]
The invention according to claim 3 is characterized in that the fuel injected from the first fuel injection nozzle has a higher boiling point than the fuel injected from the second fuel injection nozzle. According to this, even if the engine has a low combustion temperature at the time of starting the engine or the like, it is intended to obtain a combustion state as good as possible by supplying a fuel having a lower boiling point.
[0016]
At this time, as described in claim 4, light oil is injected from the first fuel injection nozzle, and gasoline having a lower boiling point than light oil is injected from the second fuel injection nozzle. Further, as described in claim 5, gasoline is injected from the first fuel injection nozzle, and propane having a lower boiling point than gasoline is injected from the second fuel injection nozzle.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram for explaining a fuel injection mechanism of the present invention. In addition, a diesel engine will be described as an example of the engine according to the present embodiment, and since each cylinder has the same configuration, only one of the cylinders will be described below, and the other cylinders will be omitted.
[0018]
The engine according to the present embodiment is a four-stroke engine of a kind called a normal compression ignition type engine. In the cylinder 1, the intake valve 6 is opened, the piston 2 is lowered, and only the air is sucked into the cylinder 1. It starts rising from the bottom dead center, and the intake valve 6 closes. At this time, the air in the cylinder 1 is compressed to a high temperature of several hundred degrees Celsius. That is, the fuel is compressed in the cylinder 1 so as to have a temperature equal to or higher than the ignition temperature of the injected fuel.
[0019]
Near the end of the compression stroke, based on a signal from an electronic control unit (hereinafter simply referred to as “ECU”) 11, the first fuel pump 10 operates and light oil from the first fuel tank 9 flows to the intake pipe 5 side. It is supplied to the provided first fuel injection nozzle 13. Then, at the timing of fuel injection, fuel is injected from the first fuel injection nozzle 13 by a signal from the ECU 11.
[0020]
In a diesel engine, unlike a gasoline engine, light oil used for fuel is injected at a high pressure of several hundreds of atmospheres at the time of fuel injection, and the fuel self-ignites due to the heat of compression of air and burns quickly. The pressure generated by this combustion pushes the piston 2 down through the top dead center to the bottom dead center. Thereafter, the exhaust valve 4 is opened, and the exhaust gas is pushed out of the cylinder 1 to the exhaust pipe 3 by the gas pressure in the cylinder 1 and the rise of the piston 2.
[0021]
The above is the basic cycle of the diesel engine. In the present invention, in addition to providing the first fuel injection nozzle 13 for injecting light oil, as shown in the drawing, the second fuel for injecting a fuel different from light oil The injection nozzle 14 is provided on the side of the intake pipe 5 so that the fuel injection by the first fuel injection nozzle 13 and the fuel injection by the second fuel injection nozzle 14 can be switched based on a signal from the ECU 11.
[0022]
Here, the second fuel injection nozzle 14 provided on the intake pipe 5 side will be further described. This is in addition to the fuel injection nozzle (first fuel injection nozzle 13) conventionally provided on the intake pipe 5 side. A fuel injection nozzle (second fuel injection nozzle 14) different from the above is additionally provided. As a result, the fuel injection mechanism of the present invention can be easily installed on a conventional engine, and environmental measures are promoted. Alternatively, a member in which the first fuel injection nozzle 13 and the second fuel injection nozzle 14 are arranged in the intake pipe 5 in advance may be prepared as a separate member, and the separate member may be replaced and installed in a conventional engine. good.
[0023]
By adopting such a fuel injection mechanism, a diesel engine has a constant engine speed and has a medium / low load (constant load) as is often seen in a constant speed operation of, for example, about 60 km / hour. In the operating state of the engine, the fuel consumption rate is often better than that of the gasoline engine.
[0024]
However, an engine operating state in which the engine speed increases from a low rotation speed to a high rotation speed and is under a high load, for example, at the time of starting or acceleration for obtaining a predetermined speed which is often observed at 30 km / h or less. Then, the exhaust gas from the diesel engine becomes a problem as described in the related art.
[0025]
Therefore, instead of the fuel injection of the light oil from the first fuel injection nozzle 13, the second fuel injection nozzle 14 provided on the intake pipe 5 side, which is a feature of the present invention, is switched to the fuel injection of the fuel different from the light oil. Things. Since light oil is a fuel that is difficult to vaporize, if a compressed state suitable for combustion of light oil is not obtained, it will adhere to the cylinder wall and the like in the cylinder 1 and cause soot and the like.
[0026]
Therefore, as the fuel injected from the second fuel injection nozzle 14, even in such a state, a hydrocarbon-based fuel having a low boiling point, which is more easily vaporized than light oil, is selected in order to obtain a better combustion state than light oil. As the hydrocarbon-based fuel, gasoline, kerosene, heavy oil, and the like can be selected, but it is preferable to select gasoline in consideration of price, environmental measures, and the like.
[0027]
Next, switching between the fuel injection from the first fuel injection nozzle 13 and the fuel injection from the second fuel injection nozzle 14 will be described in more detail.
[0028]
As described above, the signal from the ECU 11 is the first signal in the engine operating state where the engine speed is constant and the engine is in a medium / low load state, as is often seen at a constant speed of about 60 km / hour, for example. Fuel injection with light oil by the fuel injection nozzle 13 is performed.
[0029]
In the present invention, such an operation state of the engine is referred to as “steady operation”, and the engine speed and the engine load in the operation state are stored in the ROM or the temporary RAM of the ECU 11 to determine the operation state. Threshold.
[0030]
On the other hand, since the engine operating state such as when starting is often seen at 30 km / h or less and the engine speed rises from a low rotation point to a high rotation and is under a high load state is not a steady operation, the present invention In the following, such an operation state of the engine will be referred to as “unsteady operation”.
[0031]
As described above, when the operating state of the engine is in the unsteady operating state, the ECU 11 does not send a signal for fuel injection to the fuel pump 10 and the first fuel injection nozzle 13, and the second fuel injection nozzle 14 and the fuel pump A signal for fuel injection is sent to 8.
[0032]
When a signal is sent from the ECU 11 to the fuel pump 8, the signal is activated, and gasoline is supplied to the second fuel injection nozzle 14 from the fuel tank 7 in which gasoline is stored. Here, when the signal is not transmitted from the ECU 11 to the first fuel injection nozzle 13, the fuel is not supplied. However, a mechanism for shutting off the fuel supply is provided in a part of the intake pipe 5, thereby stopping the fuel supply. You may do it.
[0033]
When gasoline is injected into the cylinder 1 from the second fuel injection nozzle 14, the process proceeds to a general combustion cycle in a gasoline engine, and when the piston 2 rises near the top dead center, spark discharge from the spark plug 12 occurs. It is ignited, causing a combustion explosion, and the piston 2 is pushed down. Here, although not particularly shown, since the gasoline and light oil have different compression ratios, when switching to gasoline injection by the second fuel injection nozzle 14, adjustment is made to obtain a compression ratio suitable for gasoline combustion. .
[0034]
According to the present embodiment, the first fuel injection nozzle 13 and the second fuel injection nozzle 14 are provided on the intake pipe 5 side, respectively, so that the fuel to be injected can be accurately switched and supplied according to the operating state of the engine. It is possible to do.
[0035]
As for the fuel injection nozzle, as shown in FIG. 1, the first fuel injection nozzle 13 and the second fuel injection nozzle 14 are provided on the intake pipe 5 side, respectively, but the invention is not limited to this.
[0036]
FIG. 2 is a schematic configuration diagram showing another embodiment regarding the arrangement position of the fuel injection nozzle. As shown, it is also possible to provide the first fuel injection nozzle 13 on the intake pipe 5 side and the second fuel injection nozzle 14 on the cylinder head.
[0037]
Although the position of the fuel injection nozzle is not particularly shown, the first fuel injection nozzle 13 is provided on the cylinder head and the second fuel injection nozzle 14 is provided on the intake pipe 5 side, contrary to the position shown in FIG. They can be provided, or both the first fuel injection nozzle 13 and the second fuel injection nozzle 14 can be provided on the cylinder head.
[0038]
Further, in the present embodiment, two types of fuel injection nozzles of the first fuel injection nozzle 13 and the second fuel injection nozzle 14 are used in order to surely switch the fuel injection, but the invention is not limited to this. Not something.
[0039]
That is, since it is only necessary to enable switching of fuel injection which is a feature of the present invention, for example, it is also possible to use only one common type fuel injection nozzle having both functions of light oil injection and gasoline injection. is there. In the case of the common fuel injection nozzle, only one fuel injection nozzle is required, so that the fuel injection nozzle can be easily mounted on an existing engine such as a diesel engine.
[0040]
Furthermore, in the present embodiment, a diesel engine has been described as an example of an engine. However, the present invention is not limited to this, and the fuel injection mechanism of the present invention can be installed in a gasoline engine. In the case of a gasoline engine, the fuel injected from the first fuel injection nozzle 13 is gasoline, and the fuel injected from the second fuel injection nozzle 14 is the fuel injected from the first fuel injection nozzle 13 as described above. A lower boiling fuel is selected. From the viewpoint of environmental measures and the like, propane is used as fuel injected from the second fuel injection nozzle 14. Although propane was used here, it is generally possible to use natural gas such as methane, butane or pentane.
[0041]
【The invention's effect】
As described above, according to the present invention, the first fuel injection nozzle and the second fuel injection nozzle for injecting a different type of fuel from the fuel injected from the first fuel injection nozzle are provided, and By enabling the fuel injection by these fuel injection nozzles to be switched in accordance with the operating state of the engine, appropriate fuel injection can be ensured, so that the exhaust gas is cleaner than when only one type of fuel is used. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram for explaining a fuel injection mechanism of an engine according to the present invention.
FIG. 2 is a schematic configuration diagram for explaining another embodiment according to the present invention.
[Explanation of symbols]
Reference Signs List 1 cylinder 2 piston 3 exhaust pipe 4 exhaust valve 5 intake pipe 6 intake valve 11 electronic control unit 13 first fuel injection nozzle 14 second fuel injection nozzle

Claims (5)

In a fuel injection mechanism of an engine provided with a fuel injection nozzle,
A first fuel injection nozzle for injecting fuel during steady operation of the engine;
A second fuel injection nozzle for injecting a fuel different from the fuel other than during the steady operation,
Control means for switching between fuel injection by the first fuel injection nozzle and fuel injection by the second fuel injection nozzle;
With
The control means includes:
The operating state of the engine is calculated, and fuel is injected from the first fuel injection nozzle when it is determined that the engine is in the steady operation state. A fuel injection mechanism for an engine, wherein fuel injection is performed by the second fuel injection nozzle instead of fuel injection. The engine fuel injection mechanism according to claim 1, wherein the unsteady operation state is such that the engine is operated under a high load to obtain a predetermined speed. 3. The fuel injection mechanism according to claim 1, wherein the fuel injected from the first fuel injection nozzle has a higher boiling point than the fuel injected from the second fuel injection nozzle. 4. The fuel for an engine according to any one of claims 1 to 3, wherein the fuel injected from the first fuel injection nozzle is light oil, and the fuel injected from the second fuel injection nozzle is gasoline. Injection mechanism. The fuel for an engine according to any one of claims 1 to 3, wherein the fuel injected from the first fuel injection nozzle is gasoline, and the fuel injected from the second fuel injection nozzle is propane. Injection mechanism.

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