JPH0633768A - Subsidiary chamber ignition internal combustion engine - Google Patents

Abstract

PURPOSE:To perform stable lean combustion in a subsidiary chamber ignition internal combustion engine. CONSTITUTION:In a subsidiary chamber ignition internal combustion engine provided with a subsidiary chamber 6 of communicating with a combustion chamber 4 through a nozzle 8 and a spark plug 7 of appearing in the subchamber 6, the engine provides an assist air type subfuel injection valve 14 for injecting fuel and air together to the subsidiary chamber 6 in a compression stroke and only air in an exhaust stroke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an auxiliary chamber ignition type internal combustion engine.

[0002]

2. Description of the Related Art In a premixed ignition type internal combustion engine having a carburetor and a fuel injection valve in an intake passage, there is a problem that output characteristics and exhaust emission are deteriorated due to fuel transportation delay during transient operation. In order to solve this, a sub-chamber ignition type internal combustion engine in which a spark plug is exposed to a sub-chamber communicating with the combustion chamber and fuel is directly injected into the sub-chamber is considered.

As a conventional sub-chamber ignition type internal combustion engine, for example, the one disclosed in Japanese Unexamined Patent Publication No. 52-47132 discloses a combustion chamber 54 defined by a piston 53 and a combustion chamber as shown in FIG. Sub-chamber 55 communicating with 54 and sub-chamber 5
The fuel injection valve 56 and the spark plug 57 facing the fuel cell 5 are provided.

In the intake stroke in which the piston 53 descends, air is sucked into the combustion chamber 54 from the intake passage 52 as the intake valve 51 is opened, and fuel is injected from the fuel injection valve 56 into the sub chamber 55. The fuel is directly injected and creates a relatively rich air-fuel mixture in the sub chamber 55 near the compression top dead center to enhance the ignitability by the spark plug 57.

[0005]

However, in such a conventional device, since the injection timing of the fuel injection valve 56 is set in the intake stroke, most of the fuel injected in the intake stroke is compressed. I escaped to the combustion chamber 54 in the process,
When performing lean combustion, there is a problem in that the air-fuel mixture concentration in the sub chamber 55 cannot be sufficiently increased near the compression top dead center, and the ignitability by the spark plug 57 is impaired.

Further, since the fuel is directly injected from the fuel injection valve 56 into the sub-chamber 55, which is a narrow space, a wall flow of the fuel is likely to occur, the fuel and air are not sufficiently mixed, and the combustibility and the exhaust gas are exhausted. There was a problem that the emission was deteriorated.

In view of the above problems, the present invention has an object to realize stable lean combustion in a sub chamber ignition type internal combustion engine.

[0008]

According to the present invention, in a sub-chamber ignition type internal combustion engine having a sub-chamber communicating with a combustion chamber through a nozzle and an ignition plug facing the sub-chamber, fuel is directly injected into the sub-chamber. A fuel supply unit for injecting air into the sub chamber to atomize the fuel injected from the fuel supply unit, and to inject fuel and air into the sub chamber at least in the compression stroke.
And a control means for injecting only air in the exhaust stroke.

[0009]

In the compression stroke in which the piston rises, the fuel supply means and the air injection means inject the fuel and air into the sub chamber together, so that the air-fuel mixture in the sub chamber is prevented from escaping to the combustion chamber. The air-fuel mixture in the chamber is maintained at a predetermined rich air-fuel ratio regardless of the air-fuel ratio in the combustion chamber, and stable ignitability can be maintained.

Similarly, in the compression stroke, fuel and air are injected together into the sub-chamber, so that atomization of the fuel in the sub-chamber and mixing of the fuel and air are promoted, and the wall of the fuel in the sub-chamber is a narrow space. It is possible to prevent the flow from being generated, and since the strong gas flow is generated in the sub chamber due to the jetted air flow, the ignitability can be enhanced.

As a result, even when lean-burning is performed at an air-fuel ratio that is considerably less than the stoichiometric air-fuel ratio as a whole, stratification of the air-fuel mixture that collects most of the fuel in the vicinity of the spark plug is achieved, and it is stabilized in the sub-chamber with ignition. By generating the initial flame kernel and ejecting a strong combustion flame from the injection port into the combustion chamber, smooth lean combustion is realized.

By injecting air from the air supply means into the sub-chamber during the exhaust stroke, the scavenging of the sub-chamber is sufficiently performed, and stable ignitability in the next cycle can be maintained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which the present invention is applied to a four-stroke internal combustion engine will be described below with reference to the accompanying drawings.

As shown in FIG. 1, a combustion chamber 4 is defined between an engine block (cylinder head) 1 and a piston 3, and a sub chamber 6 is formed in the center of the combustion chamber 4 via a dome-shaped cap 5. Is defined. A spark plug 7 faces the sub chamber 6, and an assist air type sub fuel injection valve 14 faces a communication pipe 16.

The dome-shaped cap 5 has a spark plug boss portion 18
Is inserted into the combustion chamber 4 from above, and the upper end flange portion 19 is fastened via a sleeve 20 screwed to the spark plug boss portion 18,
The spark plug 7 is screwed and attached to the inside of the sleeve 20.

A plurality of nozzles 8 are formed in the cap 5,
The sub chamber 6 communicates with the combustion chamber 4 via the injection port 8.

As a first fuel supply means, a main fuel injection valve 15 is provided in the intake port 11 as shown in FIG. In the combustion chamber 4, two intake valves 13 and an exhaust valve 12 are provided around the sub chamber 6, and each intake valve 13 includes an intake port 11
Each exhaust valve 12 opens and closes the exhaust port 10 at a predetermined timing in synchronization with the engine rotation.

The assist air type auxiliary fuel injection valve 14 provided as the second fuel supply means and the air injection means is
As shown in FIG. 3, a fuel inlet 21, an air inlet 22 and an outlet 23 are provided, and fuel and air are simultaneously injected from the outlet 23.

A predetermined pressurized fuel is supplied to the fuel inlet 21 via a fuel pipe (not shown), and the sub fuel injection valve 14 is opened by opening a solenoid valve incorporated therein to receive a drive pulse. A predetermined amount of fuel corresponding to the period is injected from the outlet 23.

As shown in FIG. 3, an air pipe 24 is connected to the air inlet 22, and the pressurized air stored in the pressure accumulator 27 passes through the air gallery 26 and the solenoid valve 25 provided for each cylinder. Supplied. Pressurized air discharged from the air pump 28 is stored in the pressure accumulating container 27 via the regulator 29. As a result, when the solenoid valve 25 is opened, the pressurized air is ejected from the outlet 23 of the auxiliary fuel injection valve 14 and is supplied to the auxiliary chamber 6 through the communication pipe 16 while being mixed with the injected fuel.

The spark plug 7 is supplied with the high voltage generated in the ignition coil from the ignition device 31,
A spark discharge is generated between the electrodes 9 to ignite the mixture gas compressed in the sub chamber 6.

The control device 32 inputs detection signals of various operating states, controls the fuel injection amount and injection timing from the main fuel injection valve 15 and the sub fuel injection valve 14, and ejects air through the solenoid valve 25. In addition to controlling the timing, the ignition timing of the ignition device 31 that ignites the spark plug 7 is controlled.

In the control device 32, as shown in FIG. 4, the ignition timing is set before the compression top dead center, the fuel injection timing of the main fuel injection valve 15 is set from the intake stroke to the beginning of the compression stroke, and the auxiliary fuel is set. The fuel injection timing of the injection valve 14 is set to the compression stroke, and the air injection timing of the auxiliary fuel injection valve 14 is also set to be divided into the compression stroke and the exhaust stroke. That is, the auxiliary fuel injection valve 14 is configured to inject fuel and air simultaneously in the compression stroke and inject only air in the exhaust stroke.

The control device 32 changes the fuel injection amount of the main fuel injection valve 15 according to the engine load, but controls the fuel injection amount of the sub fuel injection valve 14 to be constant regardless of the operating state.
As a result, a small amount of fuel is always injected from the auxiliary fuel injection valve 14, and before the compression top dead center at which the auxiliary fuel injection valve 14 finishes injection, a predetermined amount suitable for ignition by the spark plug 7 is provided in the auxiliary chamber 6. The air-fuel ratio mixture is filled.

Next, the operation will be described.

In the intake stroke in which the piston 3 descends, the fuel injected from the main fuel injection valve 15 is sucked into the combustion chamber 4 while mixing with the air through the intake passage, and the mixture gas having a predetermined concentration is mixed in the combustion chamber 4. Is filled.

Subsequently, in the compression stroke in which the piston 3 rises, fuel and air are injected together from the sub-fuel injection valve 14 into the sub-chamber 6, thereby preventing the air-fuel mixture from escaping from the sub-chamber 6 to the combustion chamber 4. As a result, the air-fuel mixture in the sub chamber 6 is kept at a predetermined rich air-fuel ratio regardless of the air-fuel ratio in the combustion chamber 4, and stable ignition performance can be maintained.

Similarly, in the compression stroke, when the in-cylinder pressure is equal to or lower than a predetermined value, the fuel and the air are injected into the sub chamber 6 together, so that atomization of the fuel in the sub chamber 6 and mixing of the fuel and the air are promoted. It is possible to prevent a wall flow of the fuel from being generated in the sub-chamber 6 which is a narrow space, and a strong gas flow is generated in the sub-chamber 6 by the injected air flow, so that the ignitability is enhanced.

As a result, even when lean-burning is performed at an air-fuel ratio that is considerably thinner than the stoichiometric air-fuel ratio as a whole, the air-fuel ratio of the sub-chamber 6 is made thicker than the average air-fuel ratio of the combustion chamber 4 and before the compression top dead center. Most of the fuel can be collected in the vicinity of the spark plug 7, which is at the ignition timing, to stratify the air-fuel mixture, generate a stable initial flame kernel in the sub chamber 6, and generate a strong combustion flame at each nozzle 8
From the above to the combustion chamber 4 to diffuse and burn the air-fuel mixture in the combustion chamber 4. In this way, a smooth lean burn based on stable ignition is realized, and fuel consumption is reduced, exhaust emission is improved, and high output is achieved.

Further, the fuel injected from the auxiliary fuel injection valve 14 collides with the cap 5 having a high temperature together with the air, thereby cooling the cap 5 by the latent heat of vaporization of the fuel, preventing self-ignition, and overheating the cap 5. Can be prevented.

By injecting the pressurized air from the sub fuel injection valve 14 into the sub chamber 6 in the exhaust stroke, the scavenging inside the sub chamber 6 is sufficiently performed and the ignition of the next cycle can be stabilized. .

Next, in another embodiment shown in FIG. 5, the pressurized air stored in the pressure accumulating container 27 is distributed from the air gallery 26 to the air pipe 24 through the distributor 33.

The distributor 33 includes a rotary valve 34 that rotates in synchronization with the engine rotation. The rotary valve 34 has a port 34a that communicates with each air pipe 24 in the compression stroke.
There is a notch 34b communicating with the air pipe 24 from the compression stroke to the expansion stroke and the exhaust stroke, and the air is distributed to the auxiliary fuel injection valve 14 of each cylinder according to the ignition order.

The distributor 33 and the solenoid valve 25 in the above embodiment may be omitted and the pressurized air may be constantly supplied to the auxiliary fuel injection valve 14.

Next, another embodiment shown in FIG. 6 and FIG.
In an engine having one intake valve 12 and one exhaust valve 11 in each cylinder, the cap 5 is arranged with a predetermined angle θ. The top surface 3a of the piston 3 is recessed.

In this case, the cap 5 has a screw portion 35 which is screwed to the spark plug boss portion of the engine block on the outside thereof and a screw portion 36 which is screwed to the spark plug 7 on the outside thereof. A single injection port 8 is opened in the cap 5 between the intake valve 12 and the exhaust valve 11.

Further, as shown in FIG.
One nozzle 8 is shown in FIG. 9, and three nozzles 8 are shown in FIG.
As shown in 0, four injection holes 8 may be formed respectively.

Assuming that the volume of the sub-chamber 6 is V and the sum of the opening areas of the injection ports 8 is S, the ejection speed of the combustion gas ejected from the injection ports 8 into the combustion chamber 4 increases as V / S increases, and combustion is performed. Since the combustion in the chamber 4 is accelerated, the ignition timing may be delayed. Further, as V / S becomes smaller, the combustion chamber 4
There is a tendency that the limit value of the air-fuel ratio of the Further combustion chamber 4
The stronger the intake swirl generated at 1, the more the combustion gas from the nozzles 8 goes around the cap 5, so the number of nozzles 8 may be smaller.

Next, in another embodiment shown in FIG. 11, a light beam type ignition plug 41 is provided facing the sub chamber 6.

The light beam type ignition plug 41 is provided with a convex lens 42 on the upper portion of the cap 5, and the focal length of the convex lens 42 is 10
The light beam (laser light), which is set to about mm and is sent at a predetermined ignition timing from a light emitting device (not shown), is collected in the central portion of the sub chamber 6.

In this way, the light beam type spark plug 41 ignites the air-fuel mixture in the central portion of the sub-chamber 6, so that the electrode 9 located above the sub-chamber 6 ignites the air-fuel mixture as in the above-described embodiment. As compared with the above-mentioned one, the ejection of flame from each ejection port 8 to the combustion chamber 4 can be accelerated, and the combustibility can be improved.

The cap 5 is made of stainless steel and its inner surface 5a is mirror-finished, or a multilayer film is vapor-deposited on its inner surface 5a to finish the reflectance of the inner surface 5a to 90 to 95%.

Then, as shown in FIG. 12, the light beam is condensed by the convex lens 42 at the point A located in the center of the sub chamber 6, and then reflected on the inner surface 5a of the cap which is concavely curved and recessed. By condensing light again at the point B located in the center of the chamber 6, the ignition effect can be obtained at these two points with respect to the air-fuel mixture in the sub chamber 6, and the combustibility can be further enhanced.

Further, since the deposits such as carbon on the inner surface 5a of the cap have a self-cleaning action of being burned off by the light beam, the portion where the light beam hits can always maintain a predetermined reflectance.

[0045]

As described above, according to the present invention, in a sub-chamber ignition type internal combustion engine including a sub-chamber communicating with a combustion chamber via a nozzle and a spark plug facing the sub-chamber, fuel is directly fed to the sub-chamber. Fuel supply means for injecting, and air injection means for injecting air into the sub chamber to atomize the fuel injected from the fuel supply means,
Since the control means for injecting fuel and air together at least in the compression stroke and injecting only air in the exhaust stroke is provided in the sub-chamber, the air-fuel mixture in the sub-chamber has a predetermined air-fuel ratio regardless of the air-fuel ratio of the combustion chamber. Maintained, sufficient scavenging is secured, smooth lean combustion based on stable ignition is realized, fuel consumption is reduced,
Exhaust emissions are improved and higher output is achieved.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an engine showing an embodiment of the present invention.

FIG. 2 is a schematic plan view of the same engine.

FIG. 3 is a block diagram of an air supply system of the same.

FIG. 4 is a timing chart showing fuel and air injection timings.

FIG. 5 is a configuration diagram of an air supply system showing another embodiment.

FIG. 6 is a schematic plan view of an engine showing still another embodiment.

FIG. 7 is a vertical sectional view taken along line XX of FIG.

FIG. 8 is a schematic plan view of an engine showing still another embodiment.

FIG. 9 is a schematic plan view of an engine showing still another embodiment.

FIG. 10 is a schematic plan view of an engine showing still another embodiment.

FIG. 11 is a longitudinal sectional view of an engine showing still another embodiment.

FIG. 12 is a configuration diagram of the light beam type ignition plug.

FIG. 13 is a vertical sectional view of an engine showing a conventional example.

[Explanation of symbols]

3 Pistons 4 Combustion chambers 5 Caps 6 Sub-chambers 7 Spark plugs 8 Injection ports 11 Intake ports 14 Sub-fuel injection valves (fuel supply means and air supply means) 15 Main fuel injection valves 24 Air piping 25 Solenoid valves 32 Control device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location F02M 63/00 P 7825-3G 69/00 310 E 7825-3G

Claims (1)

[Claims] 1. A sub-chamber communicating with the combustion chamber through a nozzle,
In a sub-chamber ignition type internal combustion engine having a spark plug facing the sub-chamber, fuel supply means for directly injecting fuel into the sub-chamber and air injected into the sub-chamber to atomize the fuel injected from the fuel supply means An auxiliary chamber ignition type internal combustion engine, comprising: an air injection means; and a control means for injecting fuel and air together into the auxiliary chamber at least in a compression stroke and injecting only air in an exhaust stroke.