JPH06235329A - Spark ignition type engine - Google Patents

Abstract

PURPOSE:To improve fuel consumption capacity and emission capacity of an engine by providing a means to control a gaseous fuel supply port, a means to supply air to the gaseous fuel supply port for scavenging air and a means to stratify air-fuel mixture of a hydrocarbon fuel in the center of a combustion chamber. CONSTITUTION:Hydrogen gas formed with a fuel reformer 62 is supplied to a hydrogen supply injector 63 through a hydrogen introduction passage 65. This hydrogen supply injector 63 supplies a specified amount of hydrogen gas to an accessory cell 60 with specified pressure and specified timing. A one-way valve 68, which allows air to freely flow into the accessory cell 60 from a No.2 intake port 4 but stops the air flowing into the No. 2 intake port 4 from the accessory cell 60, is provided inside a communicating passage 67. Because a hydrogen supply passage 69 is opened near the upper end of the accessory cell 60 and swirl is formed by hydrogen gas flowing into the accessory cell 60, interior of the accessory cell 60 is scavenged further effectively. Thus fuel consumption capacity and emission capacity are improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark ignition type engine for assisting the ignition / combustion of a mixture of hydrocarbon-based fuel and air, which is a gaseous fuel having a good ignitability such as hydrogen gas. Is.

[0002]

2. Description of the Related Art Generally, in a spark ignition type engine for an automobile, a mixture of hydrocarbon fuel such as gasoline and air is compressed by a piston in a combustion chamber (a working chamber in the case of a rotary piston engine). After that, it can be ignited and burned by the spark plug.
Further, such a spark ignition type engine has a characteristic that the leaner the air-fuel mixture is, the more the fuel efficiency and the emission performance are improved although the engine output is reduced. However, the NOx generation rate is the theoretical air-fuel ratio (A / F = 1
Since it is slightly higher than 4.7) on the lean side (A / F is about 16), if the air-fuel ratio is made slightly leaner than the stoichiometric air-fuel ratio, the emission performance for NOx may deteriorate.

[0003] Therefore, it is preferable to make the air-fuel mixture as lean as possible to improve fuel consumption performance and emission performance, especially at low load where high output is not required or during normal operation. However, the leaner the air-fuel mixture, the poorer the ignitability or combustibility of the air-fuel mixture, so that there is a limit to the lean air-fuel mixture.

In order to improve this, a swirl port is used as the intake port to generate a swirl (vortex flow) in the combustion chamber when the load is low, and the swirl is used to move the fuel around the center of the combustion chamber, that is, around the spark plug. A method of increasing the ignitability / combustibility of the air-fuel mixture by so-called stratification (stratification) of the air-fuel mixture is widely used from the past. However, since hydrocarbon-based fuels such as gasoline originally have poor ignitability, the lean limit cannot be sufficiently increased even by such stratification. In addition,
The lean limit is a limit value on the lean side that can secure the required minimum ignitability and combustion chamber.

Therefore, a sub chamber communicating with the combustion chamber through the communication hole is provided, and a spark plug is arranged facing the sub chamber, while a gas for supplying gaseous fuel such as hydrogen gas having a good ignitability to the sub chamber. A fuel supply means is provided, and in the combustion process, first, the spark plug ignites and burns the gaseous fuel in the sub-chamber, and the flame generated by the combustion of this gaseous fuel ensures a mixture of hydrocarbon-based fuel and air in the combustion chamber. There has been proposed a spark ignition type engine capable of igniting and burning (see, for example, Japanese Patent Laid-Open No. 62-191632).

Further, in addition to the intake port opened and closed by the intake valve, a sub-port that opens toward a spark plug provided in the combustion chamber, a sub-port opening / closing valve that opens and closes the sub-port, and a hydrogen port in the sub-port. A gas fuel supply means for supplying a gas fuel with good ignitability such as gas is provided, the sub-port opening / closing valve is opened at the time of spark discharge at the spark plug, and the spark plug is covered with the gas fuel at the time of spark discharge to burn the gas fuel. A spark ignition engine is proposed in which the ignition and combustion of a mixture of a hydrocarbon fuel and air is assisted by a flame generated by the spark ignition engine (for example, Japanese Patent Laid-Open No. 53-17807).
(See Japanese Patent Publication).

[0007]

However, in a conventional spark ignition type engine having a sub chamber as disclosed in, for example, Japanese Patent Laid-Open No. 62-191632, a gas fuel in the sub chamber is fed to the combustion chamber. In order to prevent leakage or mixture mixture in the combustion chamber from entering the sub-chamber as much as possible, the communication hole between the sub-chamber and the combustion chamber is made quite narrow, so the scavenging property in the sub-chamber becomes poor and gaseous fuel However, there is a problem that the good ignition performance of the above can not be fully utilized and the lean limit cannot be sufficiently increased.

On the other hand, in the conventional spark ignition type engine provided with the auxiliary port as disclosed in Japanese Patent Laid-Open No. 17807/53, for example, the auxiliary port opening / closing valve must be provided at the top of the combustion chamber. There is a problem that the intake valve area or the intake port opening area cannot be sufficiently secured, the ventilation efficiency increases, the filling efficiency decreases, and the engine output decreases.

The present invention has been made in order to solve the above-mentioned problems of the prior art. It is a gaseous fuel having a good ignitability such as hydrogen gas, and ignites a mixture of hydrocarbon fuel and air. It is an object of the present invention to provide a means capable of sufficiently assisting ignition / combustion of an air-fuel mixture and sufficiently enhancing charging efficiency for a spark ignition type engine that assists combustion.

[0010]

In order to achieve the above object, a first aspect of the present invention is provided with a hydrocarbon-based fuel supply means for supplying a hydrocarbon-based fuel to a combustion chamber through an intake passage, and a hydrocarbon-based fuel supply means provided in the combustion chamber. In a spark ignition engine provided with a gas fuel supply port for supplying a gas fuel having a higher ignitability than a hydrocarbon fuel around the spark plug, at least the air-fuel ratio of the mixture of the hydrocarbon fuel is theoretical When it is leaner than the fuel ratio, the gas fuel control means for controlling the gas fuel supply port and the intake stroke are set so that the gas fuel is supplied to the combustion chamber at a predetermined time between the latter half of the intake stroke and the first half of the compression stroke. Scavenging air supply means for supplying scavenging air to the gaseous fuel supply port, and stratification means for stratifying the mixture of hydrocarbon fuels in the central portion of the combustion chamber are provided. To provide a flower-ignition engine.

According to a second aspect of the present invention, in the spark ignition type engine according to the first aspect of the present invention, the gaseous fuel control means is arranged at the opening of the gaseous fuel supply port to the combustion chamber and the latter half of the intake stroke to the first half of the compression stroke. There is provided a spark ignition engine characterized by being a timing valve which is opened at a predetermined time between.

According to a third aspect of the present invention, in a spark ignition engine provided with a hydrocarbon fuel supply means for supplying a hydrocarbon fuel to the combustion chamber through an intake passage, a sub chamber opened to the combustion chamber is provided. A spark ignition characterized in that a spark plug is arranged facing the sub chamber, and a gas fuel supply means for supplying a gas fuel having an ignitability higher than that of a hydrocarbon fuel to the sub chamber is provided. Provides an expression engine.

According to a fourth aspect of the present invention, in the spark ignition engine according to the third aspect, at least when the air-fuel ratio of the mixture of hydrocarbon fuel is leaner than the theoretical air-fuel ratio, the latter half of the intake stroke to the first half of the compression stroke. Gas fuel control means for controlling the gaseous fuel supply means so that the gaseous fuel is supplied to the sub-chamber at a predetermined time between, and a scavenging air supply means for supplying scavenging air to the sub-chamber during the intake stroke. And a stratification means for stratifying an air-fuel mixture of hydrocarbon fuel in the center of the combustion chamber.

According to a fifth aspect of the present invention, in the spark ignition engine according to the third or fourth aspect, the gas fuel supply hole to the sub chamber of the gas fuel supply means is opened in the sub chamber in the tangential direction of the sub chamber. To provide a spark ignition type engine.

According to a sixth aspect of the present invention, in the spark ignition type engine according to the second or fifth aspect of the invention, the scavenging air supply means includes a communication passage that communicates the intake passage with the gaseous fuel supply port or the sub chamber. (EN) A spark ignition engine characterized by comprising a one-way valve interposed in a communication passage and allowing only a flow of air from an intake passage to a gaseous fuel supply port or a sub chamber.

A seventh invention is the spark ignition engine according to the second or fifth invention, wherein the gaseous fuel control means is
Provided is a spark ignition engine characterized in that a gaseous fuel supply port or a gaseous fuel supply hole is controlled so that gaseous fuel is supplied to a combustion chamber or a sub chamber even in a high load region.

[0017]

EXAMPLES Examples of the present invention will be specifically described below. <First Embodiment> As shown in FIGS. 1 to 3, basically, in each cylinder (only one is shown) of a spark ignition engine CE using gasoline, which is a kind of hydrocarbon fuel, as a fuel. , When the first and second intake valves 1 and 2 are opened, the first and second independent intake passages 5 and 5 via the first and second intake ports 3 and 4,
6, a mixture of gasoline and air is sucked into the combustion chamber 7, the mixture is compressed by a piston 8, and then ignited and burned by a flame of hydrogen gas ignited by an ignition plug 9, When the first and second exhaust valves 10 and 11 are opened,
The process of exhausting the combustion gas to the first and second independent exhaust passages 14 and 15 via the first and second exhaust ports 12 and 13 is repeated.

By the continuous repetition of such a process, the piston 8 reciprocates in the axial direction in the cylinder bore, and the reciprocating motion of the piston 8 is performed via the connecting rod 16, the crank pin 17, and the crank arm 18. The rotary motion is converted and transmitted to the crankshaft 19. A high voltage is applied to the spark plug 9 from the direct ignition coil 20 at a predetermined timing, and the high voltage causes a spark discharge in the electrode portion of the spark plug 9. The first and second independent exhaust passages 14 and 15 are gathered on the downstream side into one common exhaust passage 41, and the common exhaust passage 41 is provided with a catalytic converter 42 for purifying exhaust gas. An O ₂ sensor 72 for detecting the O ₂ concentration of the exhaust gas (that is, the air-fuel ratio)
Are provided in the common exhaust passage 41.

The first and second intake ports 3 and 4 are the intake side halves.
While opening to the top surface of the combustion chamber 7 in (left half in FIGS. 1 to 3), the first and second exhaust ports 12 and 13 are exhaust side half (right in FIG. 1 to FIG. 3). It opens at the top surface of the combustion chamber 7. The first intake port 3 is a tangential port or a helical port that can generate swirl in the combustion chamber 7. The first intake port 3 corresponds to the "stratification means" described in the claims.

Near the center of the combustion chamber 7 in plan view, above the combustion chamber 7, there is a substantially cylindrical sub-chamber 60 communicating with the combustion chamber 7 through a communication hole 75, the axis of which is the cylinder bore. It is formed in a positional relationship that almost coincides with the axis line,
The spark plug 9 is arranged facing the sub chamber 60.
That is, the spark plug 9 is arranged such that its electrode portion projects downward from the upper end surface of the sub chamber 60. Here, the communication hole 75 has a small diameter in order to prevent leakage of hydrogen gas in the sub chamber 60 to the combustion chamber 7 as much as possible.

In order to supply air to the combustion chamber 7 of each cylinder, a single common intake passage 21 whose upstream end is open to the atmosphere.
In the common intake passage 21, an air cleaner 22 for removing dust in intake air, an air flow sensor 23 for detecting an intake air amount, and an accelerator pedal (see FIG. An electric throttle valve 25 that is opened / closed according to the amount of depression (not shown) is interposed. A temperature sensor 71 for detecting the intake air temperature is provided in the air cleaner 22. The downstream end of the common intake passage 21 is connected to a surge tank 26 that stabilizes the flow of intake air.
The upstream ends of the first and second independent intake passages 5 and 6 of each cylinder are connected to 6.

The common intake passage 21 is provided with a bypass intake passage 27 that bypasses the electric throttle valve 25 and allows air to pass therethrough. In the bypass intake passage 27, the flow rate of the air flowing in the bypass intake passage 27 is provided. ISC valve 2 that controls the idle speed by adjusting
8 is installed.

For the first independent intake passage 5, a fuel for injecting gasoline (hydrocarbon fuel) into the air in the first independent intake passage 5 to generate a mixture of gasoline and air. An injection valve 31 is provided. This fuel injection valve 31
The fuel injection amount of the air-fuel ratio A / F of the air-fuel mixture is
It is preferably controlled by a control unit (not shown) so as to follow a target air-fuel ratio set according to (throttle opening, engine speed, etc.). The fuel injection valve 31 corresponds to "hydrocarbon-based fuel supply means" described in the claims. Specifically, the target air-fuel ratio is set to approximately the theoretical air-fuel ratio (A / F = 14.7) in order to increase the output in an operating region requiring high engine output, such as a high load region, while the low load is set. In a driving range where engine output is not so required, such as a range, the lean limit is set in order to improve fuel efficiency and emission performance. In addition,
As will be described later, since the air-fuel mixture is strongly ignited and burned by the flame generated by the combustion of hydrogen gas, the lean limit is greatly increased as compared with a normal gasoline engine.

An on-off valve 32 is provided in the second independent intake passage 6.
The on-off valve 32 is opened and closed by an actuator 33 composed of a negative pressure responsive diaphragm device. Specifically, by the three-way valve 35,
Whether the negative pressure in the surge tank 26 or the atmospheric pressure is introduced into the pressure chamber of the actuator 33 through the negative pressure passage 34 is switched, and when the negative pressure is introduced into the pressure chamber, the actuator 33 opens and closes the valve. When the valve 32 is closed and the atmospheric pressure is introduced into the pressure chamber, the opening / closing valve 32 is opened. The on-off valve 32 is closed in a low load region or the like, and at this time, air is supplied to the combustion chamber 7 only from the first intake port 3, a strong swirl is generated in the combustion chamber 7, and an air-fuel mixture is generated in the combustion chamber 7. Stratified,
This improves the ignitability and combustibility of the air-fuel mixture. The on-off valve 32 is opened in a high load area,
At this time, air is supplied from both intake ports 3 and 4 into the combustion chamber 7 so that the charging efficiency is improved.

A blow-by gas passage 37 equipped with a PCV valve 36 is provided for introducing blow-by gas generated in the engine (crank chamber) into the surge tank 26.
Is provided. Further, a fresh air introduction passage 38 for supplying a part of the air in the common intake passage 21 into the engine is provided in order to accelerate the discharge of the blow-by gas.

The fuel supply system for supplying gasoline to the fuel injection valve 31 will be described below. In this fuel supply system, the gasoline in the fuel tank 45 is replaced by the fuel filter 46.
After being sucked into the fuel pump 47 through the fuel pump 47, it is discharged at a predetermined discharge pressure from the fuel pump 47 and is supplied to the fuel injection valve 31 through a fuel supply passage 48 in which a filter 49 is interposed. Excess gasoline that is not injected by the fuel injection valve 31 is returned to the fuel tank 45 through a fuel return passage 51 in which a pressure regulator 52 that controls the fuel pressure is provided. In order to eliminate the influence of the intake negative pressure, the intake negative pressure in the surge tank 26 is introduced through the negative pressure introducing passage 53.

The air containing gasoline vapor in the fuel tank 45 is basically released to the surge tank 26 through the in-tank air release passage 54 in order to prevent diffusion of the gasoline vapor into the atmosphere. ing. Then, in the tank air release passage 54,
A separator 55 for separating the gasoline mist from the released air in order from the upstream side in the direction of air flow,
A two-way valve 56, a canister 57 for adsorbing gasoline vapor in the released air, and an orifice 58.
And a duty solenoid valve 59 are interposed.

By the way, in this embodiment, there is provided a fuel reformer for producing hydrogen gas from gasoline, which is a fuel, for assisting ignition and combustion of a mixture of gasoline and air. That is, a branch fuel supply passage 61 that branches from the fuel supply passage 48 is provided immediately downstream of the filter 49, and the downstream end of the branch fuel supply passage 61 has a fuel reformer 6 filled with a fuel reforming catalyst.
Connected to 2. Here, the fuel reforming catalyst is a well-known catalyst that decomposes gasoline, which is a compound of hydrogen and carbon, to generate hydrogen. The gaseous fuel for assisting the ignition / combustion of the air-fuel mixture of gasoline and air is not limited to hydrogen gas, and needless to say, any gaseous fuel having high ignitability may be used.

The hydrogen gas generated in the fuel reformer 62 is supplied to the hydrogen supply injector 63 through the hydrogen introduction passage 65. The hydrogen supply injector 63 supplies a predetermined amount of hydrogen gas to the sub chamber 60 through the hydrogen supply passage 69 at a predetermined pressure and at a predetermined timing. Two check valves 64a and 64b are provided in the hydrogen supply passage 69. Further, a pressure gauge 66 for detecting the pressure in the hydrogen supply passage 69 between the check valves 64a and 64b is provided. Here, the hydrogen supply passage 69 is a hydrogen supply hole (gaseous fuel supply hole) formed by cutting the wall portion in the engine body. The hydrogen supply injector 63 corresponds to the "gaseous fuel control means" recited in the claims. Further, the series of hydrogen gas supply system corresponds to the "gaseous fuel supply means" described in the claims.

The downstream end of the hydrogen supply passage 69 (hydrogen supply hole) is opened in the inner peripheral surface of the sub-chamber 60 in the vicinity of the upper end of the sub-chamber 60 so as to face the circumferential direction of the sub-chamber. There is. As a result, the hydrogen gas flowing into the sub chamber 60 from the hydrogen supply passage 69 (hydrogen supply hole) produces a swirl (lateral vortex) in the sub chamber 60.

Further, a communication passage 67 for communicating the sub chamber 60 with the second intake port 4 (or the second independent intake passage 6) is provided, and the communication passage 67 is provided from the second intake port 4 to the sub chamber 60. To the second intake port 4 while allowing air to freely flow into the one-way valve 68
Is installed. Here, the communication passage 67 is opened in the inner peripheral surface of the sub chamber 60 in the vicinity of the upper end portion of the sub chamber 60 so as to face the circumferential direction of the sub chamber. by this,
The air flowing into the sub chamber 60 from the communication passage 67 creates a swirl (lateral vortex) in the sub chamber 60. In addition,
The communication passage 67 and the one-way valve 68 correspond to “scavenging air supply means” described in the claims.

Here, the communication passage 67 may communicate with the sub chamber 60 and the first intake port 3 (or the first independent intake passage 5). Further, instead of the one-way valve 68, an opening / closing valve that opens / closes at a predetermined timing in synchronization with the crankshaft 19 may be provided to allow air to flow from the second intake port 4 to the sub chamber 60 in the intake stroke. .

In the above structure, first, in the intake stroke, the negative pressure in the combustion chamber 7 reaches the sub chamber 60, so that the sub chamber 60 is depressurized, and the air in the second intake port 4 receives the communication passage 67 and the one-way valve 6.
8 into the sub chamber 60. As mentioned above,
Since the communication passage 67 is opened near the upper end of the sub chamber 60, the air flows through the sub chamber 60 and the inside of the sub chamber 60 is strongly scavenged. In addition, since the swirl is generated in the sub chamber 60, the scavenging of the sub chamber 60 is promoted by the swirl. Therefore, the residual gas in the sub chamber 60 is swept away. In addition, the air thus flowing into the sub chamber 60 further flows into the combustion chamber 7, so that the intake charging efficiency is increased,
Therefore, the engine output is increased. One-way valve 6
If an opening / closing valve is provided instead of 8, the opening / closing valve is
It suffices to open and close in synchronization with the second intake valves 1 and 2.

After the end of the intake stroke, that is, at a predetermined time of the compression stroke, a predetermined amount of hydrogen gas is injected from the hydrogen supply injector 63 into the hydrogen supply passage 69, and this hydrogen gas flows into the sub chamber 60, In the sub chamber 60, a mixture of hydrogen and air is formed. The hydrogen injection amount is preferably set so that a mixture of hydrogen and oxygen in the air having a volume ratio of about 2: 1 is formed in the sub chamber 60. As described above, since the hydrogen gas is supplied to the sub chamber 60 after the intake stroke is completed, the reverse flow of the hydrogen gas in the sub chamber 60 to the intake system is prevented. Further, hydrogen gas is supplied near the upper end portion of the sub chamber 60, and the communication hole 75
Has a small diameter, the retention rate of hydrogen gas in the sub-chamber 60 is improved, and the hydrogen gas is unnecessarily leaked to the combustion chamber 7.
Diffusion is suppressed. As described above, the hydrogen supply passage 69 is opened near the upper end of the sub chamber 60, and
Since the swirl is generated by the hydrogen gas flowing into 0, the inside of the sub chamber 60 is scavenged more effectively.

In the combustion stroke following the compression stroke, the ignition plug 9 ignites the mixture of hydrogen and air in the sub chamber 60. The mixture of hydrogen and air is
Since the ignitability is extremely high and the flammable range is very wide, the air-fuel mixture can be reliably ignited and burned. As described above, since the inside of the sub chamber 60 is strongly scavenged, the high ignitability of hydrogen gas is fully utilized.

Then, the flame generated by the combustion of hydrogen in the sub-chamber 60 is ejected into the combustion chamber 7, and the flame ignites the mixture of gasoline and air in the combustion chamber 7 reliably and strongly. Burned. Therefore, in the air-fuel ratio region where the air-fuel ratio of the mixture of gasoline and air is set to lean, such as in the low load region, the lean mixture can be reliably ignited and burned, so the lean limit should be greatly increased. Fuel efficiency and emission performance can be improved. Further, as described above, since the air-fuel mixture is stratified in the low load region or the like, the ignitability / combustibility of the lean air-fuel mixture is further enhanced. On the other hand, in an air-fuel ratio region where the air-fuel ratio of the mixture of gasoline and air is almost the stoichiometric air-fuel ratio, such as in the high load region, since the ignition / combustion of the mixture is assisted by the flame due to the combustion of hydrogen, The combustion speed of the air-fuel mixture is increased, knocking is suppressed, and knock resistance is significantly improved.

<Second Embodiment> A second embodiment of the present invention will be described below with reference to FIG. 4, but in order to avoid duplication of description, it is common to the first embodiment shown in FIGS. The same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. As shown in FIG. 4, in the second embodiment, the engine CE ′ is not provided with a sub chamber, and the spark plug 9 is arranged so as to face the combustion chamber 7.
Further, the fuel injection valves 31a and 31b are respectively connected to the intake ports 3 and 4.
Is provided. And the upstream end is the intake port 3, 4
A hydrogen supply port 81 that communicates with the hydrogen supply port 81 and is opened at the top surface of the combustion chamber 7 with its downstream end facing the spark plug 9 is provided. A valve 82 (timing valve) is provided, and a communication valve 83 for opening and closing the valve 82 is provided near the upstream end. Further, a hydrogen supply injector 63 is arranged facing the hydrogen supply port 81.

In the engine CE 'according to FIG. 5, the intake valves 1 and 2 and (G ₁ ), the exhaust valves 10 and 11 (G ₂ ), and the communication valve 8
3 and (G ₃ ), the opening and closing timing of the hydrogen supply valve 82 (G ₄ ) is shown. As is clear from FIG. 5, the intake valve 1,
2, the communication valve 83, and the hydrogen supply valve 82 are both opened, and the air in the intake ports 3 and 4 is supplied to the combustion chamber 7 through the hydrogen supply port 81. Therefore, in the intake stroke, the combustion chamber 7 is discharged from both the intake ports 3 and 4 and the hydrogen supply port 81.
Air is supplied inside. Therefore, the hydrogen supply port 8
By arranging 1 or the hydrogen supply valve 82, even if the intake valve area or the intake port opening area is reduced, the charging efficiency is sufficiently increased and the engine output is increased. Further, air around the ignition plug 9 is scavenged by the air flowing into the combustion chamber 7 from the hydrogen supply port 81. Therefore, the ignitability of the hydrogen gas or the air-fuel mixture in the combustion process described later is enhanced.

After the intake stroke, that is, in the compression stroke, the communication valve 83 is closed and the hydrogen supply valve 82 is opened. Then, a predetermined amount of hydrogen gas is supplied from the hydrogen supply injector 63 to the hydrogen supply port 81 at a predetermined timing, the hydrogen gas flows into the combustion chamber 7, and most of it gathers around the spark plug 9.

Then, in the combustion stroke following the compression stroke, a high voltage is applied to the spark plug 9, and spark discharge occurs in the electrode portion. Here, since hydrogen gas having extremely high ignitability is gathered around the ignition plug 9, the flame generated by the combustion of this hydrogen gas strongly assists the ignition / combustion of the mixture of gasoline and air. The ignitability and combustibility of the air-fuel mixture are significantly improved. Therefore, also in the second embodiment, as in the case of the first embodiment, the lean limit can be increased in the low load region or the like to improve the fuel efficiency and the emission performance, and the knock resistance in the high load region or the like can be obtained. Can be increased.

As shown in FIG. 6, the hydrogen supply valve 82
May be left open from the intake stroke to the compression stroke (G ₄ '). In this case as well, the same effect as in the case of FIG. 5 can be obtained.

[0042]

According to the first aspect of the present invention, when the air-fuel ratio of the mixture of hydrocarbon fuel is lean, a gas having a high ignitability is obtained at a predetermined time between the latter half of the intake stroke and the first half of the compression stroke. Since the fuel is supplied around the spark plug, the flame produced by the combustion of the gaseous fuel ignites the mixture.
Combustion is assisted. Therefore, the lean limit can be increased when the load is low, and the fuel consumption performance and emission performance can be improved. Also, since scavenging air is supplied to the gaseous fuel supply port during the intake stroke, the scavenging property around the spark plug is enhanced, and the gaseous fuel concentration around the spark plug is enhanced during ignition, and the ignitability of the air-fuel mixture is increased. Flammability is further enhanced. Moreover, since the scavenging air supplied to the combustion chamber is used for combustion, the charging efficiency is increased and the engine output is increased. Further, since the air-fuel mixture of hydrocarbon fuel is stratified in the center of the combustion chamber, the ignitability and combustibility of the air-fuel mixture are further enhanced.

According to the second invention, basically, the same operation and effect as those of the first invention can be obtained. Further, since the supply of the gaseous fuel to the combustion chamber is controlled by the timing valve, the gaseous fuel can be supplied at the most appropriate time, and the ignitability and the combustibility of the air-fuel mixture are further enhanced.

According to the third aspect of the invention, in the combustion stroke, the ignition plug first ignites and burns the highly ignitable gaseous fuel, and the flame of this gaseous fuel consists of hydrocarbon fuel and air. The air-fuel mixture is ignited and burned. Therefore, the ignitability and combustibility of the air-fuel mixture are enhanced, the lean limit can be significantly increased, and the fuel efficiency performance and the emission performance are enhanced.

According to the fourth invention, basically, the same operation and effect as the third invention can be obtained. Furthermore, since scavenging air is supplied to the sub-chamber during the intake stroke, the scavenging ability in the sub-chamber is enhanced, and the high ignitability of gaseous fuel can be fully utilized, and the ignitability and combustibility of the air-fuel mixture can be enhanced. Is further increased and the lean limit is increased. In addition, since the scavenging air supplied to the sub chamber is used for combustion, the charging efficiency is increased and the engine output is increased. Further, since the air-fuel mixture of hydrocarbon fuel is stratified in the center of the combustion chamber, the ignitability and combustibility of the air-fuel mixture are further enhanced.

According to the fifth invention, basically the same operation and effect as those of the third or fourth invention can be obtained. Further, since the opening of the gas fuel supply hole is directed in the tangential direction of the sub chamber, a swirl is generated in the sub chamber, the scavenging of the sub chamber is promoted by the swirl, and the high ignitability of the gas fuel is utilized more effectively. The lean limit can be further increased.

According to the sixth invention, basically, the same operation and effect as those of the second or fifth invention can be obtained. Further, since the scavenging air supply means is composed of the communication passage and the one-way valve, the structure of the scavenging air supply means is simplified.

According to the seventh invention, basically, the same operation and effect as those of the second or fifth invention can be obtained. further,
Even in the high load region, the gaseous fuel assists the ignition / combustion of the air-fuel mixture composed of hydrocarbon fuel and air, so that the flame propagation speed of the air-fuel mixture is increased, the occurrence of knocking is suppressed, and the knock resistance is improved. The nature is enhanced.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a spark ignition type engine showing a first embodiment of the present invention.

FIG. 2 is an elevational view of a partial cross-section around a spark plug of the engine shown in FIG.

FIG. 3 is an explanatory plan view around a port of the engine shown in FIG.

FIG. 4 is an explanatory plan view around a port of a spark ignition type engine showing a second embodiment of the present invention.

5 is a diagram showing an example of opening / closing timings of various valves of the engine shown in FIG.

FIG. 6 is a diagram showing another example of opening / closing timings of various valves of the engine shown in FIG. 4.

[Explanation of symbols]

 CE, CE '... Spark ignition engine 3,4 ... First and second intake ports 5,6 ... First and second independent intake passages 7 ... Combustion chamber 9 ... Spark plugs 31, 31a, 31b ... Fuel injection valve 60 ... Sub-chamber 63 ... Hydrogen supply injector 67 ... Communication passage 68 ... One-way valve 69 ... Hydrogen supply passage (hydrogen supply hole) 81 ... Hydrogen supply port 82 ... Hydrogen supply valve 83 ... Communication valve

Front page continuation (72) Inventor Fumihiko Saito 3-1, Fuchu-cho Shinchi, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Inventor Kazuhiko Hashimoto 3-1-1 Shinchu, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd.

Claims (7)

[Claims] 1. A hydrocarbon-based fuel supply means for supplying a hydrocarbon-based fuel to the combustion chamber through an intake passage, and a gas having a higher ignitability than the hydrocarbon-based fuel around an ignition plug provided in the combustion chamber. In a spark ignition engine equipped with a gas fuel supply port for supplying fuel, at least when the air-fuel ratio of the mixture of hydrocarbon fuels is leaner than the stoichiometric air-fuel ratio, from the latter half of the intake stroke to the first half of the compression stroke. Gas fuel control means for controlling the gas fuel supply port so that the gas fuel is supplied to the combustion chamber at a predetermined time between, and scavenging air supply means for supplying scavenging air to the gas fuel supply port in the intake stroke. And a stratification means for stratifying a mixture of hydrocarbon fuel in the center of the combustion chamber, the spark ignition type engine. 2. The spark ignition engine according to claim 1, wherein the gaseous fuel control means is provided at an opening of the gaseous fuel supply port to the combustion chamber and is provided between the latter half of the intake stroke and the first half of the compression stroke. A spark ignition engine characterized in that it is a timing valve that is opened at a predetermined time. 3. A spark ignition engine provided with a hydrocarbon fuel supply means for supplying a hydrocarbon fuel to the combustion chamber via an intake passage, wherein a sub chamber opening to the combustion chamber is provided. A spark ignition engine, characterized in that a spark plug is arranged in front of the fuel cell, and a gas fuel supply means for supplying a gas fuel having a higher ignitability than a hydrocarbon fuel to the sub chamber is provided. 4. The spark ignition engine according to claim 3, wherein at least when the air-fuel ratio of the mixture of hydrocarbon fuels is leaner than the stoichiometric air-fuel ratio, from the latter half of the intake stroke to the first half of the compression stroke. Gas fuel control means for controlling the gaseous fuel supply means so that the gaseous fuel is supplied to the sub-chamber at a predetermined time, scavenging air supply means for supplying scavenging air to the sub-chamber in the intake stroke, A spark ignition engine, comprising: stratification means for stratifying a mixture of hydrogen-based fuel in a central portion of a combustion chamber. 5. The spark ignition engine according to claim 3 or 4, wherein the gas fuel supply hole to the sub chamber of the gas fuel supply means is opened in the sub chamber in a tangential direction of the sub chamber. A spark ignition engine characterized by the fact that 6. The spark ignition engine according to claim 2 or 5, wherein the scavenging air supply means communicates the intake passage with the gaseous fuel supply port or the auxiliary chamber, and the communication passage. And a one-way valve that allows only the flow of air from the intake passage to the gaseous fuel supply port or the sub chamber. 7. The spark ignition engine according to claim 2 or 5, wherein the gaseous fuel control means supplies the gaseous fuel to the combustion chamber or the auxiliary chamber even in a high load region. A spark ignition engine characterized by being adapted to control a port or a gaseous fuel supply means.