JP2003254063A - Combustion chamber of engine and combustion method of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain generation of soot and nitrogen oxides by sufficiently accelerating diffusion of a fuel in a combustion chamber. <P>SOLUTION: Between a fuel injection nozzle 7 and a main combustion chamber 4, a cold inert chamber 11 is formed in which a great deal of gas inert for the fuel injected from the fuel injection nozzle 7 is present and which introduces the fuel to the main combustion chamber 4. An engine cooling water passage is provided to a cylinder head. Accordingly, an air inside the cold inert chamber 11 is cooled by an engine cooling water and is made lower in temperature than an air inside the main combustion chamber 4. As a result, ignition delay is increased to accelerate the diffusion of the fuel, thereby restraining generation of soot and nitrogen oxides. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine, particularly a diesel engine, and more particularly to a combustion chamber and a combustion method for the diesel engine.

[0002]

2. Description of the Related Art Diesel engines have advantages in thermal efficiency and durability under severe conditions (high load continuous operation) as compared with gasoline engines. However, on the other hand, nitrogen oxides NOx
However, the exhaust is not clean and is environmentally unfavorable. For example, it is discharged more than a gasoline engine or soot (particulate emission) is discharged. Therefore, reduction of NOx and soot are required for diesel engines. It is also desired to further improve the fuel efficiency of diesel engines and reduce noise.

In a diesel engine, fuel is injected from a nozzle hole of a fuel injection nozzle into a combustion chamber (compression chamber) compressed by a piston to generate a spray to burn the fuel.

In a normal diesel engine, fuel is injected into a combustion chamber (cylinder) from a nozzle hole of a fuel injection nozzle during a predetermined injection period near the top dead center (TDC) to generate combustion energy. I am trying to let you. However, since the fuel burns before it is sufficiently diffused, soot is generated and a large amount of nitrogen oxides is generated in a local high temperature field.

In order to solve these problems, it is possible to inject fuel earlier than near the compression top dead center to promote diffusion.

However, if the fuel is injected at an early stage, there is a problem in that a reverse rotation force is generated due to early ignition, resulting in deterioration of fuel efficiency, and that fuel adheres to the wall surface of the cylinder liner and is discharged as unburned fuel. Occur.

The present invention has been made in view of these circumstances, and it is an object of the present invention to sufficiently promote diffusion in the combustion chamber and suppress soot generation and nitrogen oxide generation.

[0008]

The first aspect of the present invention is to supply air into a main combustion chamber of a combustion chamber of an engine and to inject fuel from a fuel injection nozzle at a predetermined time during a compression stroke. When the mixture of air and fuel is generated and burned, a large amount of gas inert to the fuel injected from the fuel injection nozzle exists between the fuel injection nozzle and the main combustion chamber, and It is characterized in that an inert chamber leading to the main combustion chamber is formed.

As shown in FIG. 2, a large amount of gas inert to the fuel injected from the fuel injection nozzle 7 exists between the fuel injection nozzle 7 and the main combustion chamber 4, and the fuel is injected into the main combustion chamber 4. A leading inert chamber 11 is formed.

Since the inert chamber 11 is filled with a gas inert to the fuel, the ignition timing of the air-fuel mixture can be delayed and the diffusion of the fuel can be promoted. Therefore, soot generation,
Generation of nitrogen oxides can be suppressed.

A second aspect of the present invention is a combustion chamber of an engine,
When supplying air into the main combustion chamber and injecting fuel from the fuel injection nozzle at a predetermined time during the compression stroke to generate a mixture of air and fuel for combustion, the fuel injection nozzle and the main combustion chamber And a cold inert chamber having a temperature lower than that of the main combustion chamber, which is a chamber for guiding the fuel injected from the fuel injection nozzle to the main combustion chamber.

As shown in FIG. 2, a chamber for guiding the fuel injected from the fuel injection nozzle 7 to the main combustion chamber 4 between the fuel injection nozzle 7 and the main combustion chamber 4, The cold inert chamber 11 is formed at a low temperature.

Since the temperature of the cold inert chamber 11 is lower than that of the main combustion chamber 4 and is inactive to the fuel, the ignition timing of the air-fuel mixture can be delayed and the diffusion of the fuel can be promoted. Therefore, soot generation and nitrogen oxide generation can be suppressed.

The cold inert chamber 11 of the second invention is formed in the cylinder head 2a, for example, as shown in FIG.
Cooled with engine cooling water.

Water is supplied to the cold inert chamber 11 of the second invention as shown in FIG. 3, for example. Cold inert chamber 1
Since 1 is cooled to a temperature lower than that of the main combustion chamber 4 and water is supplied into the cold inert chamber 11 to make it inactive to the fuel, the ignition timing of the air-fuel mixture is delayed and the diffusion of fuel is promoted. be able to. Therefore, soot generation and nitrogen oxide generation can be suppressed.

A third aspect of the present invention is, in a combustion chamber of an engine,
While supplying air into the main combustion chamber, injecting fuel from the fuel injection nozzle at a predetermined time during the compression stroke, when producing a mixture of air and fuel and performing combustion, cover the tip of the fuel injection nozzle, A combustion gas inert chamber having a communication passage communicating with the main combustion chamber is formed, and fuel is injected from the fuel injection nozzle into the combustion gas inert chamber earlier than the predetermined time. Generating an inert gas in the inert chamber, and injecting fuel from the fuel injection nozzle at the predetermined time into the main combustion chamber via the combustion gas inert chamber in which the inert gas is generated. Characterize.

As shown in FIG. 6 (a), a combustion gas inert chamber 15 is formed which covers the tip of the fuel injection nozzle 7 and which has a communication passage 6 communicating with the main combustion chamber 4. From the fuel injection nozzle 7 to the combustion gas inert chamber 15 earlier than a predetermined time.
The fuel is injected into the inside of the combustion chamber and burned to generate an inert gas in the combustion gas inert chamber 15, as shown in FIG. 6B.

Then, as shown in FIG. 6 (c), fuel is injected from the fuel injection nozzle 7 into the combustion gas inert chamber 15 in which the inert gas is generated, at a predetermined time. Therefore, as shown in FIG. 6D, the fuel injected near the top dead center does not ignite while passing through the combustion gas inert chamber 15, and the fuel reaches the main combustion chamber 4 and diffuses. Then, the combustion starts, and the main combustion is performed in the main combustion chamber 4 outside the combustion gas inert chamber 15.

As described above, since the combustion is carried out in advance in the inert chamber 15 so that a large amount of gas inert to the fuel exists in the inert chamber 15, the ignition timing of the air-fuel mixture is delayed and the fuel is delayed. The diffusion of can be promoted. Therefore, soot generation and nitrogen oxide generation can be suppressed.

A fourth invention is characterized in that, in the third invention, the combustion gas inert chamber is formed by a bag-shaped member including the tip of the fuel injection nozzle.

As shown in FIG. 6A, the combustion gas inert chamber 15 is formed by a bag-shaped member that encloses the tip of the fuel injection nozzle 7.

A fifth invention is characterized in that, in the third invention, the combustion gas inert chamber is formed by a cover-shaped member which covers the tip of the fuel injection nozzle and is open downward.

As shown in FIG. 7A, the combustion gas inert chamber 15 is formed by a cover-shaped member that covers the tip of the fuel injection nozzle 7 and that is open at the bottom.

A sixth aspect of the present invention is, in a combustion chamber of an engine,
While supplying air into the main combustion chamber, injecting fuel from the fuel injection nozzle at a predetermined time during the compression stroke, when producing a mixture of air and fuel and performing combustion, cover the tip of the fuel injection nozzle, Forming a steam inert chamber provided with a communication passage communicating with the main combustion chamber, to supply water into the steam inert chamber earlier than the predetermined time to generate steam in the steam inert chamber, It is characterized in that fuel is injected from the fuel injection nozzle at the predetermined time into the main combustion chamber through the steam inert chamber in which the steam is generated.

As shown in FIG. 8A, a water vapor inert chamber 15 is formed which covers the tip of the fuel injection nozzle 17 and which is provided with a communication passage 6 communicating with the main combustion chamber 4. By supplying water into the water vapor inert chamber 15 earlier than a predetermined time, as shown in FIG.
As shown in (b), steam is generated in the steam inert chamber 15.

Then, as shown in FIG. 8 (c), fuel is injected from the fuel injection nozzle 17 into the water vapor inert chamber 15 in which the water vapor has been generated, at a predetermined time. The water vapor inert chamber 15 has a large amount of inert water vapor that does not ignite the fuel in the chamber due to the preceding water injection. Therefore, as shown in FIG. 8D, the fuel injected near the top dead center does not ignite while passing through the inert chamber 15, and after the fuel reaches the main combustion chamber 4 and diffuses. Combustion starts, and main combustion is performed in the main combustion chamber 4 outside the steam inert chamber 15.

As described above, since water is injected in advance into the inert chamber 15 so that a large amount of water vapor is inactive in the inert chamber 15 for the fuel, the ignition timing of the air-fuel mixture is delayed. The fuel diffusion can be promoted. Therefore, soot generation and nitrogen oxide generation can be suppressed.

A seventh invention is characterized in that, in the sixth invention, the water vapor inert chamber is formed by a bag-shaped member including the tip of the fuel injection nozzle.

As shown in FIG. 4, the water vapor inert chamber 15
Is formed of a bag-shaped member including the tip of the fuel injection nozzle 17.

An eighth invention is characterized in that, in the sixth invention, the water vapor inert chamber is formed by a cover-shaped member which covers the tip of the fuel injection nozzle and is open at the lower side.

As shown in FIG. 5, the water vapor inert chamber 15
Is formed by a cover-shaped member that covers the tip of the fuel injection nozzle 17 and is open at the bottom.

In a ninth aspect of the present invention, in an engine combustion method, fuel is injected into a local region of a combustion chamber at an early stage of a compression stroke, and first combustion is performed in the local region to carry out an inert gas. And a step of performing second combustion by injecting fuel into the combustion chamber so that the fuel passes through the local region where the inert gas is generated.

The ninth invention replaces the device invention of the third invention with a method invention.

A tenth aspect of the present invention is, in a combustion method for an engine, a step of supplying water to a local region of a combustion chamber to generate water vapor in this local region early in a compression stroke, and this water vapor is generated. And injecting the fuel into the combustion chamber so that the fuel may pass through the local region and performing combustion.

The tenth invention replaces the apparatus invention of the sixth invention with a method invention.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Each embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram used for explaining the basic structure of a combustion chamber of a diesel engine common to the embodiments described later.

FIG. 1A shows a side view of a combustion chamber of a diesel engine 1 according to a third embodiment which will be described later. FIG. 1B is an enlarged cross-sectional view of a diesel engine 1 having a fuel injection nozzle provided with a water supply passage, as will be described later, as viewed from the side.

That is, the diesel engine 1 is composed of a cylinder 2 and a piston 3 slidably arranged in the cylinder 2 and vertically reciprocating in the cylinder 2. A concave cavity 3a is formed in the upper part of the piston 3 and substantially in the center. The upper part of the piston 3 and the cylinder chamber form a main combustion chamber (compression chamber) 4. The main combustion chamber 4 is a compression chamber in which the air-fuel mixture is compressed by the piston 3 and a combustion chamber in which the fuel in the air-fuel mixture is burned. The cavity 3a occupies a main volume in the main combustion chamber 4.

Exhaust gas produced as a result of combustion in the main combustion chamber 4 is discharged to the outside air via an exhaust valve and an exhaust manifold (not shown).

The engine 1 is provided with an intake manifold and an intake valve (not shown) for supplying air. Air is supplied into the main combustion chamber 4 via the intake manifold and the intake valve.

A fuel injection nozzle, that is, an injector 7 is provided at the head of the cylinder 2, that is, the cylinder head 2a above the main combustion chamber 4.

The fuel in the fuel tank is sucked by the fuel injection pump and discharged to the fuel injection nozzle 7 through the fuel injection pipe. The fuel injection pump is a pump driven according to the rotation of the engine 1, and discharges a fixed volume of fuel per rotation. The fuel injection pump is assumed to be a common rail system. A unit injector system or a jerk type row pump may be used.

At the tip of the fuel injection nozzle 7, for example, 4
Two injection holes 8 are formed. Fuel is injected into the cylinder 2 (inside the cylinder), that is, into the main combustion chamber 4 through the injection holes 8.

When the fuel is injected from the fuel injection nozzle 7, the fuel is atomized and atomized in the main combustion chamber 4. This spray mixes with the air supplied via the intake manifold to form a mixture. When the main combustion chamber 4 is compressed and reaches the ignition temperature, the air-fuel mixture burns.

An inert chamber 15 provided on the wall surface with a communication passage 6 covering the tip of the fuel injection nozzle 7 and communicating with the main combustion chamber 4.
Are formed in the main combustion chamber 4. Specifically, the inert chamber 15 is formed by a bag-shaped member, and the nozzle 7
It is suspended by the fuel injection nozzle 7 so as to include the tip of the. The wall surface of the inert chamber 15 is formed with a plurality of communication passages 6 that connect the interior of the inert chamber 15 and the external main combustion chamber 4 to each other. In the embodiment, a plurality of communication passages 6 are formed, but it is also possible to form only one.

As will be described later, the injection hole 8 of the fuel injection nozzle 7
When the fuel is injected from the air-fuel mixture, an air-fuel mixture is first generated in the inert chamber 15, and the generated air-fuel mixture is discharged into the main combustion chamber 4 via the communication passage 6 to perform combustion.

FIG. 1 (b) shows a fuel injection nozzle 17 used in a fifth embodiment described later.

In FIG. 1B, a part of the fuel injection nozzle 17 is shown by a broken surface, and inside the fuel injection nozzle 17,
A water supply passage 9 for supplying water is formed in the inert chamber 15. A water supply port 10 is opened at the tip of the fuel injection nozzle 17, and the water supply port 10 communicates with the water supply passage 9.

The inert chamber 15 is suspended from the fuel injection nozzle 17 so as to include the water supply port 10 of the fuel injection nozzle 17.

In the fuel injection nozzle 17, the supply timing of water is controlled, and water is supplied and injected into the inert chamber 15 at a predetermined timing of the compression stroke.

In each of the embodiments described below, the main combustion chamber 4
By making a large amount of gas inert to the fuel in the chamber leading to the fuel cell, the ignition delay is increased and the diffusion of the fuel is promoted, so that soot generation and nitrogen oxide generation are suppressed.

First Embodiment In the first embodiment, as shown in FIG. 2, the fuel injected from the fuel injection nozzle 7 is mainly burned between the fuel injection nozzle 7 and the main combustion chamber 4. A cold inert chamber 11 having a function of leading to the chamber 4 and having a temperature lower than that of the main combustion chamber 4 is formed.
This cold inert chamber 11 is the inert chamber 1 described with reference to FIG.
It corresponds to 5. Specifically, as shown in FIG. 2, the fuel injection nozzle 7 is provided at a position above the cylinder head 2a as compared with FIG. A cold inert chamber 11 that connects the fuel injection nozzle 7 and the main combustion chamber 4 is formed in the cylinder head 2a. In the cylinder head 2a,
A passage is normally provided for engine cooling water to pass through.
Therefore, the cold inert chamber 11 is cooled by the engine cooling water, the air filled in the cold inert chamber 11 is cooled, and the temperature becomes lower than that of the air in the main combustion chamber 4. The engine cooling water passage and the cold inert chamber 11 are arranged so as to be close to each other,
You may make it improve the effect of cooling.

The timing chart of the first embodiment is shown in FIG.

In FIG. 10, the horizontal axis indicates the crank angle of the crankshaft for reciprocating the piston 3, and the ignition (indicated by an arrow), the fuel injection timing (indicated by a convex), and the water injection timing (hatching are shown) corresponding to the crank angle. (Indicated by) is shown.

FIG. 10 (a) shows a timing chart of a normal diesel engine. As described above, the compression stroke (bottom dead center (BDC) to top dead center (TD) is shown.
In C)), fuel is injected and ignited at a predetermined time near the top dead center (TDC).

As shown in FIG. 10 (b), in the first embodiment, fuel is injected at a timing substantially similar to the fuel injection timing of the normal diesel engine shown in FIG. 10 (a).

The cold inert chamber 11 is cooled by the engine cooling water to the extent that the air in the chamber does not ignite the fuel. Therefore, the fuel injected in the vicinity of the top dead center of the engine 1 does not ignite while passing through the cold inert chamber 11, and the fuel reaches the main combustion chamber 4 and diffuses before combustion starts. Therefore, as shown in FIG. 10 (b), the ignition timing is later than that of the normal diesel engine, although the fuel is injected at the same time as that of the normal diesel engine (see FIGS. 10 (a) and (b)). )reference).

As described above, according to the first embodiment,
Since the cold inert chamber 11 is cooled to a temperature lower than that of the main combustion chamber 4 and is inactive to the fuel, the ignition timing of the air-fuel mixture can be delayed and the diffusion of the fuel can be promoted. Therefore, soot generation and nitrogen oxide generation can be suppressed.

Second Embodiment FIG. 3 shows a second embodiment which is a modification of the first embodiment.

As shown in FIG. 3, in the second embodiment, the cylinder head 2a is the same as in the first embodiment.
A cold inert chamber 11 is formed in the interior. The cylinder head 2a has a cooling effect at the same time as improving the cooling effect.
A water supply path 12 for supplying water to 1 is formed. However, instead of forming the water supply passage 12 in the cylinder head 2a, the water supply passage 9 may be formed in the fuel injection nozzle as described in FIG. 1B.

The water supply timing is controlled, and water is supplied and injected into the cold inert chamber 11 at a predetermined time in the compression stroke. Water is inert to the fuel, delays the ignition of the fuel, and serves to promote more fuel-air mixing. In the second embodiment, a protrusion 3c having a shape corresponding to the cold inert chamber 11 is formed on the bottom surface of the cavity 3a of the piston 3.

FIG. 10C shows a timing chart of the second embodiment. As shown in FIG. 10 (c), in the second embodiment, water is first supplied into the cold inert chamber 11 at a predetermined timing of the compression stroke, and subsequently, FIG.
Fuel is injected at the same timing as the fuel injection timing of the normal diesel engine shown in (a).

The cold inert chamber 11 is cooled by the engine cooling water to the extent that the air in the chamber does not ignite the fuel. Further, by supplying water into the cold inert chamber 11, the fuel is in a more inactive state.

Therefore, the fuel injected near the top dead center is
It does not ignite while passing through the cold inert chamber 11, and combustion starts after the fuel reaches the main combustion chamber 4 and diffuses. Therefore, as shown in FIG. 10 (c), the ignition timing is later than that of the normal diesel engine, although the fuel is injected at the same timing as that of the normal diesel engine (see FIG. 10).
(See (a) and (c)). Further, since water is supplied into the inert chamber 11, the fuel becomes more inactive and the first
The ignition timing is further delayed as compared with the embodiment of FIG.
(See (b) and (c)).

As described above, according to the second embodiment,
Since the cold inert chamber 11 is cooled to a temperature lower than that of the main combustion chamber 4 and water is supplied into the cold inert chamber 11 to make it inactive to the fuel, the ignition timing of the air-fuel mixture is delayed,
The diffusion of fuel can be promoted. Therefore, soot generation and nitrogen oxide generation can be suppressed.

Third Embodiment Next, the pre-combustion is generated by the pre-injection into the inert chamber, and the ignition delay is increased by the inert gas such as carbon dioxide generated thereby to diffuse the fuel. Promote,
Therefore, an embodiment capable of suppressing soot generation and nitrogen oxide generation will be described.

In the third embodiment, as shown in FIG. 6A (as already described in FIG. 1A), the tip of the fuel injection nozzle 7 is covered and communicated with the main combustion chamber 4. The inert chamber 15 having the communication passage 6 on the wall surface is formed in the main combustion chamber 4. Specifically, the inert chamber 15 is formed of a bag-shaped member and is suspended by the fuel injection nozzle 7 so as to include the tip of the nozzle 7.
The wall surface of the inert chamber 15 is formed with a plurality of communication passages 6 that connect the interior of the inert chamber 15 and the external main combustion chamber 4 to each other. In the embodiment, a plurality of communication passages 6 are formed, but it is also possible to form only one. An enlarged view of FIG. 6A is shown in FIG. The configuration of FIG. 4 is the same as that of FIG. 1A, except that the fuel injection nozzle 17 also serves as a nozzle for injecting water.

6 (a), (b), (c) and (d) are diagrams showing the operation of the third embodiment, in which the inert chamber 15 and the main chamber accompanying the movement of the piston 3 during the compression stroke. The change of the combustion chamber 4 is shown. The timing chart of the third embodiment is shown in FIG.

That is, as shown in FIG. 6A, at the early stage of the compression stroke, a part of the total fuel supplied from the fuel injection nozzle 7 is injected into the inert chamber 15, while the inert gas is inactive. Air is supplied from the main combustion chamber 4 into the chamber 15 through the communication passage 6, and the air and fuel are diffused and mixed in the inert chamber 15 (see the first “fuel injection” in FIG. 10D). Therefore, as shown in FIG. 6B, the air-fuel mixture in the inert chamber 15 is ignited and the pre-combustion is performed before the compression top dead center is reached. Oxygen is consumed in the inert chamber 15 due to the preceding combustion, so that in the inert chamber 15, carbon dioxide (CO2), nitrogen (N2) and water vapor (H
A large amount of inert gas such as 2O) is present (see the first “ignition” in FIG. 10D).

Next, as shown in FIG. 6C, the remaining fuel is injected into the inert chamber 15 from the fuel injection nozzle 7 near the top dead center of the compression process. As shown in FIG. 10 (d), in the third embodiment, fuel is injected at a timing substantially similar to the fuel injection timing of the normal diesel engine shown in FIG. 10 (a). The fuel supplied into the inert chamber 15 is guided to the external main combustion chamber 4 via the communication passage 6.

The inert chamber 15 contains a large amount of inert gas which does not ignite the fuel due to the preceding combustion. Therefore, as shown in FIG. 6 (d), the fuel injected near the top dead center does not ignite while passing through the inert chamber 15, and after the fuel reaches the main combustion chamber 4 and diffuses. Combustion starts, and combustion gas is generated in the main combustion chamber 4 outside the inert chamber 15. Therefore, as shown in FIG. 10 (d), the ignition timing is later than that of the normal diesel engine, although the fuel is injected at the same timing as that of the normal diesel engine (see FIGS. 10 (a) and (d)). )reference).

As described above, according to the third embodiment,
Since the combustion is performed in advance in the inert chamber 15 so that a large amount of inert gas exists for the fuel in the inert chamber 15, the ignition timing of the air-fuel mixture is delayed and the diffusion of the fuel is promoted. You can Therefore, soot generation and nitrogen oxide generation can be suppressed.

Fourth Embodiment Next, a fourth embodiment using an inert chamber having a shape different from that of the inert chamber used in the third embodiment will be described.

In the fourth embodiment, as shown in FIG. 7A, the inert chamber 15 is composed of a cover-shaped member having an opening at the bottom. That is, as shown in FIG. 7A, the inert chamber 15 is formed by a cover-shaped member and is suspended by the fuel injection nozzle 7 so as to include the tip of the nozzle 7. A plurality of communication passages 6 are formed on the wall surface of the inert chamber 15, and an opening 15 a communicating with the main combustion chamber 4 is formed in the lower portion. It is also possible to provide one communication passage 6. In the fourth embodiment, on the bottom surface of the cavity 3a of the piston 3,
Protrusion 3b having a shape corresponding to the opening 15a of the inert chamber 15
Are formed. An enlarged view of FIG. 7A is shown in FIG. The configuration of FIG. 5 is the same as that of FIG. 7A, except that the fuel injection nozzle 17 also serves as a nozzle for injecting water.

7 (a), (b), (c), and (d) are diagrams showing the operation of the fourth embodiment, in which the inert chamber 15 and the main chamber accompanying the movement of the piston 3 during the compression stroke. The change of the combustion chamber 4 is shown. The timing chart of the fourth embodiment is shown in FIG.

That is, as shown in FIG. 7A, at the early stage of the compression stroke, a part of all the fuel supplied from the fuel injection nozzle 7 is injected into the inert chamber 15 in advance. , The main combustion chamber 4 in the inert chamber 15 via the communication passage 6.
More air is supplied, and air and fuel diffuse and mix in the inert chamber 15. However, as shown in FIG. 10 (e), the advanced fuel injection timing of the fourth embodiment is later than the advanced fuel injection timing of the third embodiment shown in FIG. 10 (d) (FIG. 10 ( e) first "fuel injection"). Therefore, as shown in FIG. 7B, the air-fuel mixture in the inert chamber 15 is ignited and the pre-combustion is performed before the compression top dead center is reached. Oxygen is consumed in the inert chamber 15 by this preceding combustion, so that in the inert chamber 15, there are many inert gases such as carbon dioxide (CO2), nitrogen (N2), and water vapor that are inactive to the fuel. Ready to go. In the fourth embodiment, the lower portion of the inert chamber 15 is opened, and the closed space is only temporarily formed near the compression top dead center as shown in FIG. 7B. Therefore, unlike the bag-shaped inert chamber 15 of the third embodiment, the throttling loss in the communication passage 6 can be reduced (see the first "ignition" in FIG. 10 (e)).

Next, as shown in FIG. 7C, the remaining fuel is injected from the fuel injection nozzle 7 into the inert chamber 15 near the top dead center of the compression process. As shown in FIG. 10 (e), in the fourth embodiment, fuel is injected at a timing substantially similar to the fuel injection timing of the normal diesel engine shown in FIG. 10 (a). The fuel supplied into the inert chamber 15 is guided to the external main combustion chamber 4 via the communication passage 6 and the opening 15a.

The inert chamber 15 contains a large amount of inert gas that does not ignite the fuel due to the preceding combustion. Therefore, as shown in FIG. 7D, the fuel injected near the top dead center does not ignite while passing through the inert chamber 15, and after the fuel reaches the main combustion chamber 4 and diffuses. Combustion starts, and combustion gas is generated in the main combustion chamber 4 outside the inert chamber 15. Therefore, as shown in FIG. 10 (e), the ignition timing is later than that of the normal diesel engine, although the fuel is injected at the same time as that of the normal diesel engine (see FIGS. 10 (a) and (e)). )reference).

As described above, according to the fourth embodiment,
Since the combustion is performed in advance in the inert chamber 15 so that a large amount of inert gas exists for the fuel in the inert chamber 15, the ignition timing of the air-fuel mixture is delayed and the diffusion of the fuel is promoted. You can Therefore, soot generation and nitrogen oxide generation can be suppressed.

Although the inert chamber 15 is suspended from the fuel injection nozzle 7 in both the third and fourth embodiments, the inert chamber 15 may be suspended directly from the cylinder head 2a.

Fifth Embodiment Next, by injecting water into the inert chamber, water vapor that is inactive to the fuel is generated in the inert chamber, thereby increasing the ignition delay and promoting the diffusion of the fuel. An embodiment capable of suppressing soot generation and nitrogen oxide generation will be described.

FIG. 4 shows the structure of the fifth embodiment. In the fifth embodiment, the fuel injection nozzle 17 which also serves as the water injection nozzle is used as in the case of FIG. 1B. . On the other hand, the inert chamber 15 is composed of a bag-shaped member as in the third embodiment described above.

FIGS. 8A to 8D show the states corresponding to FIGS. 6A to 6D of the third embodiment, and FIG. 10F shows the state of the fifth embodiment. The timing chart is shown.

That is, as shown in FIG. 8 (a), first, water is supplied from the fuel injection nozzle 17 into the inert chamber 15 at a relatively early stage of the compression stroke (see "Water injection" in FIG. 10 (f)). ). Further, air is supplied into the inert chamber 15 via the communication passage 6. Water is inert to the fuel, delays the ignition of the fuel, and serves to promote more fuel-air mixing.

The amount of water to be supplied depends on the engine speed,
The optimum value is determined using the load, engine cooling water temperature, intake air temperature, etc. as parameters. However, when starting the engine,
It is desirable not to inject water or to inject a small amount of water when idling or under a light load.

As described above, the inert chamber 1 is provided early in the compression stroke.
Since water and air are supplied into the fuel cell 5, as shown in FIG. 8 (b), water vapor that is inert to the fuel is generated in the inert chamber 15 until the compression top dead center is reached. In the inert chamber 15, a large amount of water vapor exists.

Next, as shown in FIG. 8C, the fuel is injected from the fuel injection nozzle 17 into the inert chamber 15 near the top dead center of the compression process. As shown in FIG. 10 (f), in the fifth embodiment, fuel is injected at a timing substantially similar to the fuel injection timing of the normal diesel engine shown in FIG. 10 (a). The fuel supplied into the inert chamber 15 is guided to the external main combustion chamber 4 via the communication passage 6.

The inert chamber 15 is
There are many inert water vapors that do not ignite fuel in the room. Therefore, as shown in FIG. 8D, the fuel injected near the top dead center does not ignite while passing through the inert chamber 15, and after the fuel reaches the main combustion chamber 4 and diffuses. Combustion starts, and combustion gas is generated in the main combustion chamber 4 outside the inert chamber 15. Therefore, as shown in FIG. 10 (f), the ignition timing is later than that of the normal diesel engine, although the fuel is injected at the same time as that of the normal diesel engine (FIGS. 10 (a), (f )reference).

As described above, according to the fifth embodiment,
Since water is injected into the inert chamber 15 in advance so that a large amount of water vapor is inactive in the inert chamber 15 for the fuel, the ignition timing of the air-fuel mixture is delayed and the diffusion of the fuel is promoted. be able to. Therefore, soot generation and nitrogen oxide generation can be suppressed.

Sixth Embodiment Next, a sixth embodiment using an inert chamber having a shape different from that of the inert chamber used in the fifth embodiment will be described.

FIG. 5 shows the configuration of the sixth embodiment. In the sixth embodiment, a fuel injection nozzle 17 that also serves as a water injection nozzle is used as in FIG. 1 (b). . On the other hand, the inert chamber 15 is composed of a cover-shaped member provided with the opening 15a, as in the above-described fourth embodiment.

FIGS. 9A to 9D show the states corresponding to FIGS. 7A to 7D of the above-described fourth embodiment, and FIG. 10G shows the state of the sixth embodiment. The timing chart is shown.

That is, as shown in FIG. 9 (a), first, water is supplied from the fuel injection nozzle 17 into the inert chamber 15 at a relatively early stage of the compression stroke (see "Water injection" in FIG. 10 (g)). ). Further, air is supplied into the inert chamber 15 via the communication passage 6.

The water injection timing of the sixth embodiment is shown in FIG.
This is a time later than the water injection time of the fifth embodiment shown in (f) (see "Water injection" in FIG. 10 (g)).

The amount of water supplied depends on the engine speed,
The optimum value is determined using the load, engine cooling water temperature, intake air temperature, etc. as parameters. However, when starting the engine,
It is desirable not to inject water or to inject a small amount of water when idling or under a light load.

As described above, the inert chamber 1 is provided early in the compression stroke.
Since water and air are supplied into the fuel cell 5, as shown in FIG. 9 (b), water vapor that is inactive to the fuel is generated in the inert chamber 15 until the compression top dead center is reached. In the inert chamber 15, a large amount of water vapor exists. In the sixth embodiment, the lower part of the inert chamber 15 is opened, and the closed space is only temporarily formed near the compression top dead center as shown in FIG. 9B. Therefore, unlike the bag-shaped inert chamber 15 of the fifth embodiment, the throttling loss in the communication passage 6 can be reduced.

Next, as shown in FIG. 9C, the fuel is injected from the fuel injection nozzle 17 into the inert chamber 15 near the top dead center of the compression process. As shown in FIG. 10 (g), in the sixth embodiment, fuel is injected at a timing substantially similar to the fuel injection timing of the normal diesel engine shown in FIG. 10 (a). The fuel supplied into the inert chamber 15 is guided to the external main combustion chamber 4 via the communication passage 6 and the opening 15a.

The inert chamber 15 is
There are many inert water vapors that do not ignite fuel in the room. Therefore, as shown in FIG. 9D, the fuel injected near the top dead center does not ignite while passing through the inert chamber 15, and after the fuel reaches the main combustion chamber 4 and diffuses. Combustion starts, and combustion gas is generated in the main combustion chamber 4 outside the inert chamber 15. Therefore, as shown in FIG. 10 (g), the ignition timing is later than that of the normal diesel engine, although the fuel is injected at the same time as that of the normal diesel engine (see FIGS. 10 (a) and (g)). )reference).

As described above, according to the sixth embodiment,
Since water is injected into the inert chamber 15 in advance so that a large amount of water vapor is inactive in the inert chamber 15 for the fuel, the ignition timing of the air-fuel mixture is delayed and the diffusion of the fuel is promoted. be able to. Therefore, soot generation and nitrogen oxide generation can be suppressed.

In the fifth and sixth embodiments, water is supplied into the inert chamber 15 to generate steam, but steam may be supplied directly instead of supplying water.

[Brief description of drawings]

1A and 1B are views showing a configuration of a fuel injection nozzle and an inert chamber according to an embodiment, and FIG. 1A is a cross-sectional view of a combustion chamber as seen from a side surface. 1 (b) is an enlarged view showing a fuel injection nozzle that also serves as a water injection nozzle.

FIG. 2 is a diagram showing a state of a combustion chamber in a compression stroke according to the first embodiment.

FIG. 3 is a diagram showing a state of a combustion chamber in a compression stroke according to a second embodiment.

FIG. 4 is a view showing a configuration of a fuel injection nozzle and an inert chamber of the embodiment, and is a view showing a fuel injection nozzle that also serves as a water injection nozzle.

5 is a diagram showing a configuration of a fuel injection nozzle and an inert chamber of the embodiment, showing an inert chamber having a shape different from that of FIG. 4 and showing a fuel injection nozzle which also serves as a water injection nozzle. is there.

6 (a), (b), (c) and (d) show the state of combustion in the combustion chamber from the compression stroke to the vicinity of the start of the expansion stroke according to the movement of the piston in the third embodiment. FIG.

7 (a), (b), (c), and (d) show the state of combustion in the combustion chamber from the compression stroke to the vicinity of the start of the expansion stroke according to the movement of the piston in the fourth embodiment. FIG.

8 (a), (b), (c) and (d) show the state of combustion in the combustion chamber from the compression stroke to the vicinity of the start of the expansion stroke of the fifth embodiment in accordance with the movement of the piston. FIG.

9 (a), (b), (c), and (d) show the state of combustion in the combustion chamber from the compression stroke to the vicinity of the start of the expansion stroke according to the movement of the piston in the sixth embodiment. FIG.

10 (a) to 10 (g) are timing charts showing ignition timing and fuel injection timing and water injection timing corresponding to the crank angle, and FIG. 10 (a) is a timing chart of a normal diesel engine. As shown in FIG.
(B)-(g) is the figure which showed the timing chart of the diesel engine of embodiment.

[Explanation of symbols]

1 engine 2 cylinders 3 pistons 4 Main combustion chamber 6 passages 7 Fuel injection nozzle 9 Water supply channel 11 Cold inert chamber 12 Water supply channel 15 Inactive room 17 Fuel injection nozzle

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 19/12 F02D 19/12 A F02M 25/022 F02M 25/07 570L 25/032 580C 25/07 570 61 / 18 340C 580 25/02 B 61/18 340 TF term (reference) 3G023 AA02 AA04 AA05 AB05 AC04 AD09 AD10 AD12 3G062 AA10 BA05 3G066 AA07 AB02 AB08 AD12 BA24 BA25 CC34 3G092 AA02 AB03 AB17 DF03 FA17 FA18 FA18

Claims (10)

[Claims] 1. In a combustion chamber of an engine, air is supplied into the main combustion chamber and fuel is injected from a fuel injection nozzle at a predetermined time during a compression stroke to generate a mixture of the air and the fuel for combustion. At this time, between the fuel injection nozzle and the main combustion chamber, there is a large amount of gas inert to the fuel injected from the fuel injection nozzle, and an inert chamber for guiding the fuel to the main combustion chamber is formed. Combustion chamber of the engine. 2. In a combustion chamber of an engine, air is supplied into the main combustion chamber and fuel is injected from a fuel injection nozzle at a predetermined time during a compression stroke to generate a mixture of air and fuel for combustion. At this time, a chamber for guiding the fuel injected from the fuel injection nozzle to the main combustion chamber between the fuel injection nozzle and the main combustion chamber, the cold inert chamber having a temperature lower than that of the main combustion chamber. The combustion chamber of the engine, which is characterized in that 3. In a combustion chamber of an engine, air is supplied into the main combustion chamber and fuel is injected from a fuel injection nozzle at a predetermined time during a compression stroke to generate a mixture of air and fuel for combustion. At this time, a combustion gas inert chamber is formed which covers the tip of the fuel injection nozzle and has a communication passage communicating with the main combustion chamber, and the combustion gas inert chamber is formed from the fuel injection nozzle earlier than the predetermined time. Fuel is injected into the active chamber to generate an inert gas in the combustion gas inert chamber, and the inert gas is generated into the main combustion chamber through the combustion gas inert chamber at the predetermined time. A combustion chamber of an engine, characterized in that fuel is injected from the fuel injection nozzle. 4. The combustion chamber for an engine according to claim 3, wherein the combustion gas inert chamber is formed by a bag-shaped member that encloses the tip of the fuel injection nozzle. 5. The combustion chamber for an engine according to claim 3, wherein the combustion gas inert chamber is formed by a cover-shaped member that covers the tip of the fuel injection nozzle and is open downward. 6. In a combustion chamber of an engine, air is supplied into the main combustion chamber, and fuel is injected from a fuel injection nozzle at a predetermined time during a compression stroke to generate a mixture of air and fuel for combustion. At this time, a water vapor inert chamber that covers the tip of the fuel injection nozzle and is provided with a communication passage that communicates with the main combustion chamber is formed, and water is supplied to the water vapor inert chamber earlier than the predetermined time. Steam is generated in the steam inert chamber, and fuel is injected from the fuel injection nozzle at the predetermined time into the main combustion chamber via the steam inert chamber in which the steam is generated. Engine combustion chamber. 7. The combustion chamber for an engine according to claim 6, wherein the water vapor inert chamber is formed by a bag-shaped member that encloses the tip of the fuel injection nozzle. 8. The combustion chamber for an engine according to claim 6, wherein the water vapor inert chamber is formed by a cover-shaped member that covers the tip of the fuel injection nozzle and is open downward. 9. An engine combustion method, comprising injecting fuel into a local region of a combustion chamber early in a compression stroke,
A step of precedingly performing the first combustion in the local region to generate an inert gas, and a step of injecting fuel into the combustion chamber so that the fuel passes through the local region in which the inert gas is generated And a step of performing combustion of the engine. 10. A combustion method for an engine, wherein water is supplied to a local region of a combustion chamber at an early stage of a compression stroke,
Combustion of an engine comprising: a step of generating water vapor in the local region; and a step of injecting fuel into the combustion chamber so that the fuel passes through the local region in which the water vapor is generated and performing combustion. Method.