JP2002364395A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine that can realize high power, low fuel consumption and appreciable emission (purification of exhaust gas). SOLUTION: The internal combustion engine 10 comprises a fuel injection valve 24 for injecting fuel of high self-ignitability into a combustion chamber 16, and a fuel injection valve 42 for injecting fuel of low self-ignitability into an intake pipe 40. An exhaust pipe 44 and the intake pipe 40 are connected by an exhaust recirculating pipe 48, which recirculates (reintroduces) part of exhaust gas. The exhaust recirculating pipe 48 is provided with a recirculating volume adjuster 52, which can adjust the recirculating volume of exhaust gas. The recirculating volume is controlled by the recirculating volume adjuster 52 operated according to a computation result by a controller 26 so that exhaust gas reaching a purifier 46 is in a stoichiometric air-fuel ratio state. An operation is thus possible for extreme efficiency, low fuel consumption and appreciable emission according to a load state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an internal combustion engine driven by burning supplied fuel in a combustion chamber of a cylinder.

[0002]

2. Description of the Related Art A so-called spark-ignition internal combustion engine in which fuel is premixed in advance and ignited and burned by spark ignition, or a so-called compression-ignited internal combustion engine in which fuel is directly injected into a combustion chamber (cylinder) for compression ignition and combustion. Is generally known.

By the way, in such an internal combustion engine,
A technique has been proposed in which gasoline is premixed, and further, light oil is directly injected into a combustion chamber to ignite and burn the premixed gas by ignition and combustion (for example, Automotive Engineering Society No. 42 (1989), or JP-A-10-23
8374). Furthermore, in order to reliably ignite the lean premix, a premix is formed in the combustion chamber in advance by using the recirculated gas, and the ignition and combustion of the mixture are
A technique for performing ignition and combustion of ignition fuel has been proposed (JP-A-2000-8966).

[0004] However, the above-mentioned article of the Society of Automotive Engineers of Japan N
o. 42 (1989), although a reduction in smoke is reported, other exhaust gas components, particularly a large amount of nitrogen oxides discharged according to the output from a medium load to a high load of the internal combustion engine, are reported. The substance is not purified and is discharged as it is, and there is room for improvement in reducing the emission of the internal combustion engine (cleaning the exhaust gas). Also, JP-A-10-238
The technology proposed in Japanese Patent No. 374 or Japanese Patent Laid-Open No. 2000-8966 only aims to reliably ignite a lean premixture, and harmful factors remain in exhaust gas components. ing.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described circumstances, and has as its object to obtain an internal combustion engine that can achieve high output, low fuel consumption, and good emission (clean exhaust gas). is there.

[0006]

An internal combustion engine according to the first aspect of the present invention comprises a first fuel supply means for supplying a first fuel having a low self-ignition property to form a premixed gas in a combustion chamber; A second fuel supply means for directly injecting the second fuel having a high self-ignition property into the combustion chamber; and a part of the exhaust gas which is taken out, recirculated to the first fuel supply system, and returned to the combustion chamber again. An exhaust gas recirculation mechanism for supplying, a purifying device including a three-way catalytic converter or an occlusion reduction type catalytic converter provided downstream of the exhaust gas recirculation mechanism in the exhaust system;
Wherein the first fuel supply means supplies the first fuel to form a premixture in the combustion chamber in advance, and the second fuel supply means brings the second fuel into the combustion chamber. In an internal combustion engine that directly injects and burns the second fuel by self-ignition to also ignite and burn a premixed air mixture of the first fuel, the amount of exhaust gas recirculation can be adjusted by the exhaust gas recirculation mechanism. The exhaust gas recirculation mechanism adjusts the amount of exhaust gas recirculated by the exhaust gas recirculation mechanism so that the exhaust gas component reaching the purification device is in a stoichiometric air-fuel ratio state.

According to the first aspect of the present invention, the first fuel is supplied by the first fuel supply means to form a premixed gas in the combustion chamber in advance, and the second fuel supply means supplies the second mixture with the second fuel supply means. The fuel is injected directly into the combustion chamber and this second
Is burned by self-ignition, and the premixed air by the first fuel is also ignited and burned. Further, a part of the exhaust gas is taken out by the exhaust gas recirculation
Is recirculated to the fuel supply system, and is again supplied to the combustion chamber and burned. Substantial exhaust gas not recirculated (recirculated) by the exhaust gas recirculation mechanism is purified by a purifying device (three-way catalytic converter or occlusion reduction type catalytic converter) and then discharged to the outside.

Thus, in the internal combustion engine according to the first aspect of the present invention, the first fuel is premixed, and the exhaust gas is re-inhaled, so that the fuel supplied from the fuel supplied to the combustion chamber is reduced. The time until ignition becomes longer, the diffusion time of the fuel before ignition can be sufficiently obtained, and operation with very small emission of smoke and the like becomes possible. Further, after the second fuel supplied directly into the combustion chamber reaches the whole area of the combustion chamber, the second fuel and the premixed first fuel are mixed with the second fuel.
All the ignition combustion of the fuel is performed. That is, the combustion period is performed in a very short time, and the combustion spreads to the air-fuel mixture at the end of the combustion chamber, the amount of unburned fuel decreases, and the amount of unburned hydrocarbons in the exhaust gas decreases. In addition, highly efficient and fuel-efficient driving becomes possible.

Further, since the exhaust gas is re-inhaled and burned, the temperature in the combustion chamber during the compression step and the expansion step can be suppressed to a low level. Spontaneous ignition combustion of fuel and spontaneous ignition of unburned mixture which may occur during combustion of pre-mixture
Combustion can be suppressed. For this reason, it becomes possible to set the combustion timing to the optimal timing, and it is possible to operate with low fuel consumption. Furthermore, since the temperature inside the combustion chamber during the compression step and the expansion step can be suppressed low by re-inhaling and burning the exhaust gas, it is possible to reduce the generation of nitrogen oxides.

Further, in the internal combustion engine according to the first aspect, the exhaust gas recirculation mechanism is provided with a recirculation amount adjusting means capable of adjusting the recirculation amount of the exhaust gas, so that the exhaust gas component reaching the purification device is stoichiometric. The recirculation amount (re-intake amount) of the exhaust gas is adjusted so as to achieve the fuel ratio state. Therefore, the exhaust gas components are set to the stoichiometric air-fuel ratio of the fuel by adjusting the re-intake of the exhaust gas, and the unburned hydrocarbons and nitrogen oxides discharged by using the purifier (three-way catalytic converter) are used. Thus, carbon monoxide can be completely purified.
Further, for example, if the combustion chamber is set to a state in which the amount of air is larger than the stoichiometric air-fuel ratio of the fuel by adjusting the re-intake of the exhaust gas, the operation in a more efficient state can be performed. The use of a storage-reduction catalyst temporarily stores the nitrogen oxides discharged at that time, and temporarily sets the exhaust gas component to the stoichiometric air-fuel ratio of the fuel during the temporary operation of the internal combustion engine. It becomes possible to purify the stored nitrogen oxides, and as a whole, highly efficient operation becomes possible.

Here, in a conventional general spark ignition engine, in order to burn an air-fuel mixture at a stoichiometric air-fuel ratio, the purpose of adjusting the amount of air to be taken in according to the amount of fuel supplied into a combustion chamber (cylinder). A throttle device is installed in the intake pipe to form a stoichiometric air-fuel mixture in the combustion chamber. For this reason, an excessive negative pressure is generated in the combustion chamber during the intake process by the throttle device in the intake pipe, and the work required for sucking air into the combustion chamber during the intake process increases. For this reason, the work obtained from the spark ignition engine is the amount obtained by reducing the work required for intake of this air from the work obtained by burning the fuel, and finally the required work from the spark ignition engine is obtained. As a result, more fuel was required, resulting in lower fuel economy.

In this regard, the internal combustion engine according to the first aspect does not require the throttle device, and adjusts the re-intake amount of the exhaust gas in order to adjust the amount of air to be taken in according to the amount of fuel to be supplied. However, the work required for sucking air into the combustion chamber during the intake process due to the generation of excessive negative pressure in the combustion chamber during the intake process does not occur, and as a result, the internal combustion engine finally required The amount of fuel for obtaining the work load from the engine can be made smaller than that of the spark ignition engine.

In a conventional general spark ignition engine, the mixture is ignited and burned by a spark plug installed near the center of the combustion chamber, and the mixture is ignited and burned by the ignition plug. It is characterized by a so-called flame-propagating combustion system in which the surrounding air-fuel mixture is ignited and burned, and this combustion operation is sequentially performed to burn all the air-fuel mixture in the combustion chamber. In this combustion method, since combustion is performed sequentially, a so-called combustion time from the start of combustion to the end of combustion is long. Therefore, combustion is performed until a relatively late stage of the expansion process in the spark ignition engine. In other words, since the combustion is performed until the piston is considerably lowered from the top dead center, that is, the pressure in the combustion chamber is reduced, the work amount obtained from the pressure increase in the combustion chamber due to the combustion is relatively reduced. Become. For this reason, the amount of work from the internal combustion engine obtained by the supplied fuel is reduced, and as a result, fuel efficiency is deteriorated. In this combustion method, a so-called unburned air-fuel mixture that has not yet been burned is compressed due to a rise in pressure in the combustion chamber due to combustion, and the temperature of the unburned air-fuel mixture rises. The air-fuel mixture spontaneously ignites and burns, and a so-called knocking occurs due to the generation of combustion noise due to the spontaneous ignition. In order to avoid this knocking, the timing of the start of combustion by the spark plug was not the optimal time to obtain the maximum work amount with the supplied fuel, but was later than that time, that is, the pressure in the combustion chamber became low. The time has been set. As a result, the amount of work obtained from the supplied fuel is reduced, and as a result, fuel efficiency is deteriorated.
Also, for example, when a larger amount of air is supplied into the combustion chamber by a supercharger or the like arranged in the intake pipe for the purpose of obtaining more work, and more premixed air is formed in the combustion chamber. The pressure rise in the compression process is greater,
For this reason, the pressure and temperature of the unburned air-fuel mixture rise faster during combustion, and the amount of the unburned air-fuel mixture increases. For this reason, knocking easily occurs, and it is not possible to obtain a work amount corresponding to the supplied fuel amount.

In this regard, in the internal combustion engine according to the first aspect, since the premixed air is formed in the combustion chamber by the first fuel, and then the second fuel is directly supplied to the combustion chamber.
The second fuel supplied directly into the combustion chamber first diffuses throughout the combustion chamber, and then the second fuel spontaneously ignites and burns, and the flame of the combustion ignites the premixed gas with the first fuel. -It is characterized by combustion. For this reason, the air-fuel mixture in the entire combustion chamber, that is, the fuel, burns in a very short time and to every corner of the combustion chamber, and when the piston does not drop much from the top dead center, that is, when the pressure in the combustion chamber is high, Is performed. Therefore, the work amount obtained from the pressure increase in the combustion chamber due to the combustion becomes relatively large, and the fuel efficiency is greatly improved.

Further, since the air-fuel mixture in the combustion chamber is instantaneously burned, the compression and temperature rise of the unburned air-fuel mixture in the combustion of the conventional spark ignition engine do not occur. Due to the relatively high specific heat of the gas, the temperature rise of the premixture during the compression process is suppressed, and as a result, spontaneous ignition and combustion of the mixture and the accompanying knocking do not occur. Optimum combustion can be performed to obtain the highest work load.

On the other hand, a conventional general compression ignition internal combustion engine does not require a throttle device in an intake pipe such as a spark ignition engine, but adjusts the amount of fuel supplied directly to the combustion chamber of the internal combustion engine. Adjusting the amount of work done. Therefore, an increase in the amount of work required for sucking air into the combustion chamber during an intake process such as a spark ignition engine does not occur. However, due to this, the exhaust gas component discharged from the compression ignition internal combustion engine is not in the stoichiometric air-fuel ratio state,
The exhaust gas has a very high air content. For this reason, the reduced state of the three-way catalytic converter or the storage reduction type catalytic converter that can be used only in the so-called stoichiometric air-fuel ratio state cannot be used, and the nitrogen oxide generated in the combustion chamber due to the combustion is purified. And it is discharged as it is. In order to solve this, if the exhaust gas components are brought to the stoichiometric air-fuel ratio state by re-inhaling the exhaust gas, the combustion chamber is also in the stoichiometric air-fuel ratio state, and the individual droplets of the fuel supplied into the combustion chamber are vaporized. , Mixture formation,
Since the combustion is performed in the vicinity of these individual droplets and in a short time, the amount of oxygen necessary to completely burn the droplet fuel around the fuel droplets cannot be secured.
Unburned hydrocarbons, carbon monoxide, smoke, etc. due to incomplete combustion will be emitted.

In order to solve this problem, in the internal combustion engine according to the first aspect, the amount of fuel directly supplied to the combustion chamber required to burn all the fuel in the combustion chamber is very small, and the amount of the fuel supplied to the purification device is reduced. Since the exhaust gas is re-inhaled so that the exhaust gas component is brought to the stoichiometric air-fuel ratio state (the three-way catalysis or the occlusion-reduction type catalysis by the purifier is sufficiently performed), the combustion chamber during the compression process Temperature is kept low, and the fuel supplied directly into the combustion chamber has sufficient diffusion / mixture formation time required to start ignition / combustion after supply, resulting in direct supply into the combustion chamber. By starting ignition and combustion after the fuel spreads over the entire combustion chamber and becomes a premixed gas state, operation that does not emit unburned hydrocarbons, carbon monoxide, smoke, etc. due to incomplete combustion is achieved. The ability.

According to a second aspect of the present invention, in the internal combustion engine according to the first aspect, the first fuel supply means injects the first fuel into an intake pipe.

In the internal combustion engine according to the second aspect, it is possible to homogenize the premixed air of the first fuel which is supplied and formed in advance, and it is possible to operate the engine with extremely small emission of smoke and the like. .

According to a third aspect of the present invention, in the internal combustion engine according to the first aspect, the first fuel supply means directly injects the first fuel into the combustion chamber.
It is characterized by:

[0021] In the internal combustion engine according to the third aspect, the pre-mixed air by the first fuel supplied in advance can be formed at a location away from the wall surface of the combustion chamber. This makes it possible to eliminate an incombustible air-fuel mixture near the wall surface in the combustion chamber, reduce the amount of unburned hydrocarbons in the exhaust gas, clean the exhaust gas, and improve the efficiency of the fuel economy. Driving becomes possible.

According to a fourth aspect of the present invention, there is provided the internal combustion engine according to any one of the first to third aspects, wherein a supercharger is provided in the intake pipe.

In the internal combustion engine according to the fourth aspect, by operating in a state where the pressure change in the combustion chamber is higher, it is possible to operate with high efficiency and low fuel consumption. Furthermore, since more air can be supplied into the combustion chamber, that is, more fuel can be supplied, higher-power operation becomes possible. In addition, since the re-intake amount of the exhaust gas increases in accordance with the increase in the supplied air amount, the increase in the temperature in the combustion chamber due to the increase in the gas amount in the combustion chamber during the compression process is suppressed, and Optimal combustion without knocking can be performed in combination with the short-time combustion effect of the air-fuel mixture in the entire combustion chamber due to ignition and combustion after the directly supplied second fuel spreads throughout the combustion chamber.

According to a fifth aspect of the present invention, there is provided an internal combustion engine according to any one of the first to fourth aspects, wherein the intake valve adjusting means for changing the opening timing of the intake valve and the exhaust valve. An exhaust valve closing adjusting means for changing a closing timing is provided.

In the internal combustion engine according to the fifth aspect, the exhaust gas is once discharged from the combustion chamber to the intake pipe and re-inhaled again into the combustion chamber by opening the intake valve during the exhaust process, or the exhaust valve is opened during the intake process. The exhaust gas discharged to the exhaust pipe is re-inhaled into the combustion chamber by opening the exhaust valve, or the exhaust valve is closed earlier than the end of the exhaust process to keep the exhaust gas in the combustion chamber without discharging to the exhaust pipe. Becomes possible. As a result, it is possible to control the re-intake amount when exhaust gas is supplied again into the combustion chamber or the amount of exhaust gas retained in the combustion chamber (so-called residual gas amount) to an optimal amount according to the operation state. It can respond optimally to sudden changes in

According to a sixth aspect of the present invention, there is provided the internal combustion engine according to any one of the first to fifth aspects, further comprising an intake closing control means for changing a closing timing of the intake valve. And

[0027] In the internal combustion engine according to the sixth aspect, the temperature in the combustion chamber during the compression step can be kept low.
And the spontaneous ignition and combustion of the unburned mixture which may occur during the combustion of the premixed gas. Therefore, it is possible to set the combustion timing to the optimal timing while maintaining a high expansion ratio, and it is possible to operate with high output and low fuel consumption.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 shows the overall configuration of an internal combustion engine 10 according to a first embodiment of the present invention.

In the internal combustion engine 10, a combustion chamber 16 is constituted by a cylinder block 12 and a cylinder head 14, and a piston 18 is housed in the combustion chamber 16. This piston 18 is connected to a crankshaft 22 via a connecting rod 20. Further, the cylinder head 14 is provided with a fuel injection valve 24 as second fuel supply means. The fuel injection valve 24 is connected to an output port of the control device 26, and under the control of the control device 26, a highly self-igniting fuel such as heptane or light oil having a cetane number of 40 or more as the second fuel. Can be directly injected into the combustion chamber 16.

The combustion chamber 16 has a cylinder head 14
Are connected to each other. The intake port 28 is provided with an intake valve 32, and the exhaust port 30 is provided with an exhaust valve 34. A drive cam 36 is connected to the intake valve 32, and a drive cam 38 is connected to the exhaust valve 34.

Further, an intake pipe 40 is connected to the intake port 28. The intake pipe 40 is provided with a fuel injection valve 42 as first fuel supply means. The fuel injection valve 42 is also connected to the output port of the control device 26. Under the control of the control device 26, a low self-ignition fuel such as isooctane or gasoline having an octane number of 80 to 100 is taken as the first fuel. It can be injected into the tube 40. On the other hand, the exhaust port 30 is
4 are connected. The exhaust pipe 44 includes a purifying device 4.
6 (three-way catalytic converter or occlusion reduction type catalytic converter) is attached, and can purify nitrogen oxides, hydrocarbons, and carbon monoxide contained in exhaust gas.

An exhaust gas recirculation pipe 48 constituting an exhaust gas recirculation mechanism is provided upstream of the purification device 46 of the exhaust pipe 44.
Of the exhaust gas recirculation pipe 48.
Is connected to an intake pipe 40. Thus, a part of the exhaust gas can be taken out, recirculated to the intake pipe 40 (first fuel supply system), and supplied again into the combustion chamber 16.

In the middle of the exhaust gas recirculation pipe 48, a cooler 50,
Further, a reflux amount adjusting device 52 as a reflux amount adjusting means is provided. The recirculation amount adjusting device 52 includes an exhaust recirculation pipe 4.
8, the recirculation amount of the exhaust gas recirculated and supplied to the intake pipe 40 can be adjusted and changed, and is connected to the output port of the control device 26.

The cylinder block 12 is provided with a combustion chamber pressure sensor 54 for detecting the pressure in the combustion chamber 16. The crankshaft 22 is provided with a crank angle sensor 56.
Can be detected. Furthermore, the exhaust pipe 4
4 is provided with an exhaust air-fuel ratio sensor 58, which can detect the air-fuel ratio of exhaust gas reaching the purification device 46. Further, an accelerator mechanism for adjusting the rotation of the output shaft includes an accelerator sensor 6 for detecting a load state.
0 is provided. These combustion chamber pressure sensors 54,
The crank angle sensor 56, the exhaust air-fuel ratio sensor 58, and the accelerator sensor 60 are all connected to an input port of the control device 26.

The control device 26 performs a calculation based on a program (or a map) stored in advance and input signals from the sensors, outputs a calculation result, and outputs the calculation results to the fuel injection valve 24, the fuel injection valve 42, The recirculation amount adjusting device 52 is driven.

Next, the operation of the first embodiment will be described.

In the internal combustion engine 10 having the above configuration, the intake valve 32
Immediately after closing, the fuel having low self-ignitability in an amount corresponding to the output of the accelerator sensor 60 is injected from the fuel injection valve 42 into the intake pipe 40 as spray X. As a result, the fuel mixes with the air, and is heated in the intake pipe 40 and the intake port 28, and becomes mostly steam.

Further, the fuel vapor premixed in the intake pipe 40 and the intake port 28 is sucked into the combustion chamber 16 when the intake valve 32 is opened to perform an intake process, and is highly dispersed throughout the combustion chamber 16. And uniformly distributed, and the compression process becomes the intake valve 3
When 2 is closed, it is compressed in the combustion chamber 16.

When the piston 18 reaches the vicinity of the compression top dead center, the fuel with high self-ignition is injected from the fuel injection valve 24 into the combustion chamber 16 as spray Y over a wide range and is highly dispersed, and the fine fuel spray is dispersed in the combustion chamber. After the fuel spray is uniformly distributed, all the fuel sprays are ignited at the same time and combustion is performed. Further, by the combustion flame generated simultaneously in the entire combustion chamber 16,
The premixed gas that has been compressed in the combustion chamber 16 is ignited, and all the premixed gas in the combustion chamber 16 burns instantaneously.

Here, in order to operate the purifier 46 effectively, the recirculation amount of the exhaust gas recirculated and supplied to the intake pipe 40 is adjusted by the recirculation amount adjusting device 52, and the air-fuel ratio of the exhaust gas is controlled. Is done. That is, the control device 26
Based on input signals from the combustion chamber pressure sensor 54, the crank angle sensor 56, the exhaust air-fuel ratio sensor 58, and the accelerator sensor 60, the spray amount and the spray timing of the fuel injection valve 24,
One or more of the spray amount of the fuel injection valve 42 and the recirculation amount by the recirculation amount adjusting device 52 are controlled. Thereby, the combustion timing of the air-fuel mixture in the combustion chamber 16, the air-fuel ratio of the exhaust gas, and the shaft output are optimized.

For example, in order to effectively operate the purifier 46 (three-way catalytic converter), the exhaust air-fuel ratio sensor 5
The control device 26 performs an operation based on the detection signal of No. 8,
When it is determined that the exhaust gas component has more air than the stoichiometric air-fuel ratio state, the recirculation amount adjusting device 52 is driven so that the recirculation amount of the exhaust gas recirculated to the intake pipe 40 and supplied is increased. It is adjusted and controlled so as to reduce new air sucked into the intake pipe 40. On the other hand, on the other hand, when the control device 26 performs an operation based on the detection signal of the exhaust air-fuel ratio sensor 58 and determines that the exhaust gas component has less air than the stoichiometric air-fuel ratio state, the return is made. The flow control device 52 is driven to adjust the amount of exhaust gas recirculated to the intake pipe 40 so as to reduce the amount of recirculated exhaust gas, and is controlled to increase the amount of new air sucked into the intake pipe 40. . By these control operations, the purifying device 46 (three-way catalytic converter) functions effectively regardless of the operating state of the internal combustion engine 10 to remove nitrogen oxides, hydrocarbons, and carbon monoxide contained in the exhaust gas. Can be purified at the same time.

FIG. 2 shows various operating characteristics of the internal combustion engine 10 according to the first embodiment and a conventional spark ignition internal combustion engine (gasoline engine) and a compression ignition internal combustion engine (diesel engine). The differences are shown diagrammatically. In the figure, the internal combustion engine 10 according to the first embodiment is indicated by a thick solid line A, a gasoline engine is indicated by a thin solid line B, and a diesel engine is indicated by a broken line C.

As described above, in the internal combustion engine 10 according to the first embodiment, the first fuel (fuel having low self-ignition property) is used.
By premixing the fuel gas and by re-inhaling the exhaust gas, the time from the fuel supply of the fuel supplied into the combustion chamber 16 to the ignition becomes longer, and the diffusion time of the fuel before the ignition is increased. Can be obtained sufficiently, and operation with very small emission of smoke and the like can be performed. In addition, after the second fuel (highly self-igniting fuel) directly supplied into the combustion chamber 16 reaches the entire area of the combustion chamber 16, all of the second fuel and the premixed first fuel are discharged. Is performed. That is, the combustion period is performed in a very short time, and the combustion spreads to the air-fuel mixture at the end of the combustion chamber, the amount of unburned fuel decreases, and the amount of unburned hydrocarbons in the exhaust gas decreases. In addition, highly efficient and fuel-efficient driving becomes possible.

In particular, in the internal combustion engine 10, since the fuel injection valve 42 as the first fuel supply means is configured to inject the first fuel into the intake pipe 40, the first fuel is supplied and formed in advance. It is possible to homogenize the premixed air of the fuel No. 1 and to operate with very little emission of smoke and the like.

Further, since the exhaust gas is re-inhaled and burned, the temperature in the combustion chamber 16 during the compression step and the expansion step can be kept low. It is possible to suppress spontaneous ignition and combustion of the fuel No. 1 and spontaneous ignition and combustion of an unburned air-fuel mixture that may occur during the combustion of the pre-air-fuel mixture. For this reason, it becomes possible to set the combustion timing to the optimal timing, and it is possible to operate with low fuel consumption. Furthermore, since the temperature in the combustion chamber 16 during the compression step and the expansion step is kept low by re-inhaling and burning the exhaust gas, the generation of nitrogen oxides can be reduced.

Further, in the internal combustion engine 10, a recirculation amount adjusting device 52 for adjusting the recirculation amount of the exhaust gas is provided in the middle of the exhaust gas recirculation pipe 48, so that the exhaust gas component reaching the purification device 46 is theoretically evacuated. The recirculation amount (re-intake amount) of the exhaust gas is adjusted so as to achieve the fuel ratio state. Therefore, the exhaust gas component is set to the stoichiometric air-fuel ratio of the fuel by adjusting the re-intake of the exhaust gas, and the unburned hydrocarbons and nitrogen oxides discharged by the purifier 46 (three-way catalytic converter) are used. Substances and carbon monoxide can be completely purified. Further, for example, if the inside of the combustion chamber 16 is set to a state in which the amount of air is larger than the stoichiometric air-fuel ratio of the fuel by adjusting the re-intake of the exhaust gas, the operation in a more efficient state becomes possible, and furthermore, the purification is performed. The use of the device 46 (storage reduction type catalyst) temporarily stores the nitrogen oxides discharged at that time, and sets the exhaust gas component to the stoichiometric air-fuel ratio of the fuel in the temporary operation of the internal combustion engine 10. In addition, it becomes possible to purify the temporarily stored nitrogen oxides, and as a whole, highly efficient operation becomes possible.

Further, in the internal combustion engine 10, the re-intake amount of the exhaust gas is adjusted in order to adjust the amount of air to be taken in according to the amount of fuel to be supplied.
The work required for sucking air into the combustion chamber 16 during the intake process due to the generation of an excessive negative pressure inside the combustion chamber does not increase, and as a result, the work required from the internal combustion engine 10 finally required is reduced. The amount of fuel to be obtained can be smaller than that of a conventional spark ignition engine.

Furthermore, in the internal combustion engine 10, the premixed air is formed in the combustion chamber 16 by the first fuel, and then the second fuel is directly supplied into the combustion chamber 16, so that the combustion chamber The second fuel directly supplied into the combustion chamber 16 first diffuses throughout the combustion chamber 16, and then the second fuel spontaneously ignites and burns. It is characterized by performing ignition and combustion. Therefore, the air-fuel mixture in the entire combustion chamber 16, that is, the fuel, burns in a very short time and to all corners of the combustion chamber 16, and the piston 18 does not drop much from the top dead center, that is, the pressure in the combustion chamber 16. All combustion is performed in a state where is high. Therefore, the amount of work obtained from the increase in the pressure in the combustion chamber 16 due to the combustion is relatively increased, and the fuel efficiency is greatly improved.

Since the air-fuel mixture in the combustion chamber 16 is instantaneously burned, the compression and temperature rise of the unburned air-fuel mixture in the combustion of the conventional spark ignition engine do not occur, and the exhaust gas is re-inhaled. Due to the relatively high specific heat of these gases, the temperature rise of the premixture during the compression process is suppressed, and as a result spontaneous ignition and combustion of the mixture and the resulting knocking do not occur. Optimum combustion can be performed to obtain the maximum amount of work according to.

Further, in the internal combustion engine 10, the combustion chamber 1
The amount of the second fuel directly supplied into the combustion chamber 16 necessary for burning all the fuel in the fuel cell 6 is very small and sufficient, and the exhaust gas component reaching the purification device 46 is in the stoichiometric air-fuel ratio state. During the compression process, the temperature in the combustion chamber 16 is kept low, and the fuel directly supplied to the combustion chamber 16 diffuses and mixes until the fuel and the combustion start after the supply. That the second fuel directly supplied into the combustion chamber 16 spreads over the entire combustion chamber 16 and ignition / combustion starts after a premixed gas state is reached. Thus, an operation that does not emit unburned hydrocarbons, carbon monoxide, smoke, and the like due to incomplete combustion can be performed.

In the internal combustion engine 10 according to the first embodiment, the first fuel having low self-ignition property is injected into the intake pipe 40 by the fuel injection valve 42. However, the present invention is not limited to this. Instead, the first fuel may be directly injected into the combustion chamber 16 (in the cylinder) by the fuel injection valve 42. In this case, the pre-mixed air with the first fuel supplied in advance can be formed at a location away from the wall surface of the combustion chamber 16. This makes it possible to eliminate an incombustible air-fuel mixture near the wall surface in the combustion chamber 16, reduce the amount of unburned hydrocarbons in the exhaust gas, and reduce the amount of clean and highly efficient exhaust gas. Driving of fuel economy becomes possible. [Second Embodiment] FIG. 3 shows the overall configuration of an internal combustion engine 70 according to a second embodiment of the present invention.

The internal combustion engine 70 has basically the same configuration as the internal combustion engine 10 according to the first embodiment described above, and the same reference numerals are given to the same components, and the description will be given. Omitted.

The driving cam 36 for driving the intake valve 32 includes:
An intake valve opening / closing timing adjusting device 72 as the intake valve opening / closing adjusting device for changing the opening timing and closing timing of the intake valve 32 and an intake valve opening / closing timing adjusting device 72 are connected. The intake valve opening / closing timing adjusting device 72 is connected to an output port of the control device 26. Further, an exhaust valve closing timing adjusting device 74 as exhaust closing adjusting means for changing the closing timing of the exhaust valve 34 is connected to the drive cam 38 for driving the exhaust valve 34. The exhaust valve closing timing adjusting device 74 is connected to an output port of the control device 26.

The internal combustion engine 70 has a supercharger 76. The supercharger 76 includes a gas turbine 78 and a centrifugal compressor 80. The gas turbine 78 is connected to the exhaust pipe 44 on the downstream side of the purification device 46.
The centrifugal compressor 80 is connected to the intake pipe 40 upstream of the fuel injection valve 42.
It is connected to the. Further, a cooler 82 is provided in the intake pipe 40 between the centrifugal compressor 80 and the fuel injection valve 42.

On the other hand, an exhaust gas recirculation pipe 84 connects a portion of the exhaust pipe 44 downstream of the supercharger 76 (gas turbine 78) and a portion of the intake pipe 40 upstream of the supercharger 76 (centrifugal compressor 80). It is connected. Thereby, a part of the exhaust gas after passing through the supercharger 76 (gas turbine 78) is taken out, recirculated to the intake pipe 40 (first fuel supply system), and supplied again into the combustion chamber 16. It is a configuration that can be used.

In the middle of the exhaust gas recirculation pipe 84, a cooler 86,
Further, a reflux amount adjusting device 88 as a reflux amount adjusting means is provided. The recirculation amount adjusting device 88 includes an exhaust recirculation pipe 8.
4, the recirculation amount of the exhaust gas recirculated and supplied to the intake pipe 40 can be adjusted and changed, and is connected to the output port of the control device 26.

The other structure is basically the same as the structure of the internal combustion engine 10 according to the first embodiment.

Next, the operation of the second embodiment will be described.

The internal combustion engine 70 having the above configuration has basically the same operation as the internal combustion engine 10 according to the above-described first embodiment.

Here, in the internal combustion engine 10 according to the first embodiment, since it is necessary to supply more fuel as the load increases, it is necessary to maintain the exhaust gas at the stoichiometric air-fuel ratio. Therefore, it is necessary to reduce the re-intake amount of exhaust gas as the output increases. For this reason, as the output increases, the effect of suppressing the rise in the temperature of the premixed gas during the compression process due to the relatively high specific heat caused by the re-intake of exhaust gas decreases, and as a result, Ignition, combustion, or knocking is likely to occur.

In this regard, in the internal combustion engine 70 according to the second embodiment, control is performed to delay the timing of closing the intake valve 32 by the intake valve opening / closing timing adjusting device 72 as the load increases. Thereby, the compression process of the air-fuel mixture in the combustion chamber 16 from the closing of the intake valve 32 to the vicinity of the piston 18 near the top dead center is shortened, thereby suppressing the temperature rise of the air-fuel mixture during the compression process. Thus, the occurrence of knocking of ignition and combustion can be avoided. Therefore, it is possible to perform the optimal combustion that can obtain the maximum amount of work according to the supplied fuel.

Further, in the internal combustion engine 70, since the intake air is pressurized by the supercharger 76 and is forcibly supplied to the combustion chamber 16, the rate at which the amount of recirculated exhaust gas in the air-fuel mixture in the combustion chamber 16 decreases is reduced. You. Therefore, when the load reaches a desired maximum value, the air-fuel ratio of the air-fuel mixture in the combustion chamber 16 can be set to the stoichiometric air-fuel ratio, and a desired maximum load can be obtained.

Further, since the total gas amount in the combustion chamber 16 for the same load, that is, the same fuel amount, increases, the temperature rise per unit during combustion can be suppressed, and the occurrence of knocking during ignition and combustion can be avoided. Optimum combustion that can obtain the maximum amount of work obtained from the supplied fuel can be performed. Furthermore, although the temperature of the intake air rises due to the pressurization by the supercharger 76, the air pressurized by the supercharger 76 is cooled by the cooler 82 before being supplied to the combustion chamber 16, Due to the pressurization of the intake air by the heater 76, knocking during ignition and combustion due to an increase in the temperature of the air-fuel mixture in the combustion chamber 16 does not occur.

Further, after the exhaust gas passing through the gas turbine 78 of the supercharger 76 is cooled by the cooler 86, the amount adjusted by the reflux amount adjusting device 88 is returned to the centrifugal compressor 80 of the supercharger 76. And is forcibly supplied to the combustion chamber 16 together with the air-fuel mixture. As a result, even at a higher load, the exhaust gas having a high specific heat is supplied to the combustion chamber 16 so that the exhaust gas in the exhaust pipe 44 can be brought into the stoichiometric air-fuel ratio state, and the combustion rate per unit time during combustion is increased. The rise in temperature is also suppressed, so that the occurrence of knocking during ignition and combustion can be avoided. This also enables optimal combustion capable of obtaining the maximum amount of work obtained from the supplied fuel.

Here, the control of the stoichiometric air-fuel ratio of the exhaust gas in the exhaust pipe 44 by the recirculation amount adjusting device 52 or the recirculation amount adjusting device 88 may be delayed due to a sudden change in the load. There is a possibility that purification of nitrogen oxides by 46 may not be achieved.

On the other hand, in the internal combustion engine 70, the recirculation amount adjusting device 52 or the recirculation amount adjusting device 88, the intake valve opening / closing timing adjusting device 72, and the exhaust valve closing timing adjusting device 7
This problem can be solved by using one or both of them in combination.

That is, the opening timing of the intake valve 32 by the intake valve opening / closing timing adjusting device 72 is advanced to the exhaust process before the intake process, so that the exhaust gas discharged from the combustion chamber 16 during the exhaust process is supplied to the intake port 28. Alternatively, it is discharged to the intake pipe 40. Thereafter, in order to proceed to the intake process, the combustion chamber 16 is connected to the intake port 28 or the intake pipe 40.
The exhaust gas discharged to the combustion chamber 16 is again taken into the combustion chamber 16 together with the mixture formed by the spray present in the intake port 28 or the intake pipe 40 and new air. As a result,
The same effect as the effect of the exhaust gas recirculation provided through the exhaust gas recirculation pipe 48 can be obtained.

In this case, if the timing of opening the intake valve 32 is advanced, the amount of exhaust gas discharged to the intake port 28 or the intake pipe 40 during the exhaust process increases, resulting in an increase in the exhaust gas re-intake amount. At times, the amount of exhaust gas re-inhaled into the combustion chamber 16 increases. On the other hand, if the opening timing of the intake valve 32 is delayed, the amount of exhaust gas discharged to the intake port 28 or the intake pipe 40 during the exhaust process can be reduced, and as a result, the exhaust gas is re-inhaled into the combustion chamber 16 during the intake process. The amount of exhaust gas will be reduced. The operation of the intake valve opening / closing timing adjusting device 72 is instantaneous in response to a change in load, whereby the adjustment of the re-intake amount of exhaust gas and the operation can be instantaneously and accurately performed.

Similarly, the exhaust gas re-suction amount can be adjusted by the exhaust valve closing timing adjusting device 74.

That is, the exhaust gas is discharged from the combustion chamber 16 to the exhaust port 30 or the exhaust pipe 44 during the exhaust process.
Is delayed until the intake process after the exhaust process, the exhaust port 30 or the exhaust pipe 44 from the combustion chamber 16 is closed.
The exhaust gas discharged to the combustion chamber 16 is taken in the combustion chamber 16 again. As a result, the same effect as the effect by the recirculation of the exhaust gas brought through the exhaust gas recirculation pipe 48 can be obtained.

In this case, if the timing of closing the exhaust valve 34 is delayed, the amount of exhaust gas re-inhaled into the combustion chamber 16 during the intake process of the exhaust gas discharged to the exhaust port 30 or the exhaust pipe 44 is determined. Increase. On the other hand, exhaust valve 3
If the timing of closing the valve 4 is advanced, the amount of exhaust gas discharged to the exhaust port 30 or the exhaust pipe 44 to the combustion chamber 16 during the intake process can be reduced. The amount of exhaust gas to be re-inhaled is reduced. The operation of the exhaust valve closing timing adjusting device 74 is instantaneous in response to a change in load, and thereby, the adjustment of the re-intake amount of exhaust gas and the operation can be instantaneously and accurately performed.

As described above, the internal combustion engine 70 can appropriately cope with a sudden change in load.
Purification of nitrogen oxides by the purifying device 46 can be sufficiently achieved.

The internal combustion engine 7 according to the second embodiment
Even in the case of 0, the first fuel may be directly injected into the combustion chamber 16 (in the cylinder) by the fuel injection valve 42 as in the case of the internal combustion engine 10 described above.

[0074]

As described above, the internal combustion engine according to the present invention has an excellent effect that high output, low fuel consumption, and good emission (clean exhaust gas) can be realized. .

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an internal combustion engine according to a first embodiment of the present invention.

FIG. 2 shows an internal combustion engine according to a first embodiment of the present invention;
FIG. 4 is a diagram showing differences in various operating characteristics between a conventional spark ignition internal combustion engine (gasoline engine) and a compression ignition internal combustion engine (diesel engine).

FIG. 3 is an overall configuration diagram of an internal combustion engine according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 internal combustion engine 16 combustion chamber 24 fuel injection valve (second fuel supply means) 26 control device 42 fuel injection valve (first fuel supply means) 46 purification device 48 exhaust recirculation pipe (exhaust gas recirculation mechanism) 52 recirculation amount adjustment Device (reflux control means) 58 Exhaust air-fuel ratio sensor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F01N 3/24 F01N 3/24 U 3G301 3/28 301 3/28 301A 301C F02B 1/12 F02B 1/12 23/10 23/10 L F02D 21/08 301 F02D 21/08 301C 311 311B 23/00 23/00 P 41/02 351 41/02 351 370 370 380 380 380D 380G 43/00 301 43/00 301H 301N 301R 301Z F02M 25/07 570 F02M 25/07 570J 570L 570P F-term (reference) 3G023 AA02 AA04 AA05 AA06 AB05 AC02 AC04 AF03 AG03 3G062 AA01 AA05 BA04 BA09 FA05 FA13 GA04 GA05 GA06 GA15 GA20 3A08 BA00 DA08 FA10 FA21 FA29 FA38 3G091 AA02 AA10 AA11 AA17 AA18 AA21 AA23 AA24 AB03 AB06 BA00 BA14 BA15 BA19 CA13 CB02 CB03 CB08 DA01 DA02 DA03 DB10 DC01 EA01 EA07 EA12 EA31 EA34 FB10 FB11 GA06 HA36 HB03 HB05 HB06 3G092 AA01 AA03 BA01 DE02 AB02 DA02 DA02 AB02 FA01 FA15 FA16 FA17 FA18 HC01Z HD05Z HE03Z HF08Z 3G301 HA01 HA04 HA11 HA13 HA19 JA01 JA02 JA21 JA22 JA25 JA26 LA00 LA07 MA11 NC02 NE14 PC01Z PD04Z PE03Z PF03Z

Claims (6)

[Claims] 1. A first fuel supply means for supplying a first fuel having a low self-ignition property to form a premixed mixture in a combustion chamber, and a second fuel having a high self-ignition property directly into the combustion chamber. A second fuel supply means for injecting, an exhaust gas recirculation mechanism for extracting a part of the exhaust gas, recirculating the exhaust gas to the first fuel supply system, and supplying the exhaust gas to the combustion chamber again, A purifying device comprising a three-way catalytic converter or a storage-reduction type catalytic converter provided downstream of the exhaust system, wherein the first fuel is supplied by the first fuel supply means and premixed in the combustion chamber. Gas is formed, and the second fuel supply means injects the second fuel directly into the combustion chamber to burn the second fuel by self-ignition, thereby forming a premixed gas by the first fuel. Even ignition combustion In the internal combustion engine, the exhaust gas recirculation mechanism is provided with a recirculation amount adjusting means capable of adjusting the recirculation amount of the exhaust gas, and the exhaust gas recirculation mechanism is controlled so that an exhaust gas component reaching the purification device is in a stoichiometric air-fuel ratio state. An internal combustion engine, wherein the amount of exhaust gas recirculated by the engine is adjusted. 2. The internal combustion engine according to claim 1, wherein said first fuel supply means injects said first fuel into an intake pipe. 3. The internal combustion engine according to claim 1, wherein said first fuel supply means injects said first fuel directly into said combustion chamber. 4. The internal combustion engine according to claim 1, further comprising a supercharger in the intake pipe. 5. An apparatus according to claim 1, further comprising one or both of an intake valve opening adjusting means for changing the opening timing of the intake valve and an exhaust valve closing adjusting means for changing the closing timing of the exhaust valve. An internal combustion engine according to any one of claims 1 to 4. 6. The internal combustion engine according to claim 1, further comprising intake closing control means for changing a closing timing of the intake valve.