JP3280015B2 - Method and apparatus for reducing nitric oxide in an internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Industrial applications]

The present invention relates to an internal combustion engine, and particularly to a nitric oxide (hereinafter referred to as NO) in a combustion chamber of a diesel engine or a gasoline engine.
The present invention relates to a method for reducing the thermal efficiency of the engine without reducing the thermal efficiency of the engine and a specific device capable of realizing the method.

[0002]

[Prior art]

Methods for reducing NO in an internal combustion engine, mainly a piston engine, are divided into out-of-cylinder post-processing represented by a three-way catalyst, in-cylinder processing represented by EGR (exhaust gas recirculation), ignition retard or injection retard.

[0003] The three-way catalyst is placed near the exhaust manifold of the engine.
It is applied to a premixed spark engine that operates near a stoichiometric mixture. The NO reduction rate is very large, reaching 70% or more, but has little effect except near the stoichiometric air-fuel ratio (air-fuel ratio of around 14.5 (gasoline)), and leaded fuel cannot be used due to lead poisoning of the catalyst. In addition, clogging and deterioration of the catalyst unit cannot be severely applied to a diesel engine that generates soot.

EGR mixes exhaust gas into a cylinder in order to lower the combustion temperature. However, soot in the exhaust gas tends to contaminate components, causing deterioration of lubricating oil and accelerating wear of moving parts. .

[0005] The method of N is performed by the Zeldovich mechanism.
O reduction is explained.

[0006]

[Number 1] _{N + NON 2 + O (1} ) N + O 2 NO + O (2) N + OHNO + H (3)

As shown in the above equations (1), (2) and (3), NO is generated in a high-temperature field by combustion by nitrogen and oxygen in the air. In each of the equations (1), (2), and (3), when the temperature increases, the flow proceeds to the NO generation side, and the temperature becomes remarkable when the temperature is 2000 to 2200K or more. Therefore, combustion that does not raise the temperature as much as possible is effective, and the EGR, ignition retard, and injection retard are performed to suppress the combustion temperature.

However, if the temperature is lowered, the thermal efficiency of the internal combustion engine deteriorates. Therefore, at present, it is difficult to reduce NO without lowering the engine performance except for the three-way catalyst. Especially the use of a catalyst since it is a diesel engine includes soot in the exhaust is not possible, effective to significantly reduce the NO _X, and engine performance, durability, and a method and apparatus do not impair the like still Not found.

[0009] Further, Japanese Patent Application No. 62-82080 discloses that the fuel injection is divided into two or more times and when the flame generated by the previous injection is extinguished, NO generated by performing the subsequent injection is converted to CH. This is intended to reduce NO by reducing it by acting in an atmosphere of 1000 to 2000 K with _three radicals, and is different from the technical idea of the present invention.

[Problems to be Solved by the Invention] As explained in the above-mentioned Zeldovich mechanism, NO generation is strongly temperature-dependent, and as the temperature rises,
It has the property that NO generation increases rapidly. Therefore, the inventors predict that in the combustion in the engine, the temperature is particularly high for a short time near the top dead center, and in particular, the high temperature portion of the flame is expected to be a main source of NO. We thought that lowering the temperature of the high temperature flame was effective in reducing NO.

Therefore, the present inventors measured and analyzed the temperature distribution in the combustion chamber and the change of the temperature distribution with time in detail. As a result, when fuel is injected and supplied to the combustion chamber, ignition combustion takes place after a short time delay in the vicinity of the spray tip in a compression ignition engine or in the vicinity of a spark plug in a spark ignition engine, and thereafter the flame develops rapidly. Since the pressure rise is large due to the fact that the piston speed is slow and the change in the volume of the combustion chamber is small, the flame generated first is adiabatically compressed and the temperature further rises, and the temperature is the highest among the flames. It turned out to be a part.

From the above analysis results, the present inventors have found that by effectively and locally cooling the high-temperature flame portion and suppressing NO generation, unnecessary temperature reduction in other flame portions is prevented. The idea was that NO emissions could be reduced while avoiding a drop in thermal efficiency.

The present invention focuses on cooling the high-temperature flame portion, and differs from the prior art in that the high-temperature portion of the flame is cooled while NO is being generated by combustion. An object of the present invention is to provide a method and an apparatus for reducing nitric oxide of an internal combustion engine, which can suppress generation and reduce the amount of released NO.

[Description of the Invention] (Constitution) The method for reducing nitric oxide of an internal combustion engine according to claim 1, which is the first invention of the present invention, is provided in a combustion chamber of a reciprocating internal combustion engine formed by a piston, a cylinder head, and a cylinder block. The fuel injection device communicates with a fuel supply source containing light oil or gasoline, injects a predetermined amount of fuel during a predetermined stroke of the internal combustion engine by a fuel supply device including a fuel injection valve, ignites the combustion, and temporarily reduces the injection rate. After that, after the main injection, the injection rate is increased from the injection rate once decreased among the injection rates of the main injection, and a predetermined amount of fuel is supplied from the fuel supply device into the same combustion chamber as the main injection. Is performed at a predetermined time to perform a secondary injection, and is a flame at an early stage of ignition generated by the main injection and has a higher temperature than other flame portions. Flame portion was cooled by the fuel spray of secondary injection of the a configuration which is adapted to brought suppress the production on the way nitric oxide is generated to reduce the discharge of said nitric oxide by combustion.

(Operation) With the above configuration, the method for reducing nitric oxide of an internal combustion engine of the present invention has the following operation.

When the piston rises near the top dead center at the end of the compression stroke, the pressure and temperature increase due to compression. At that time, the main injection is performed from the fuel injection valve facing the combustion chamber, and the fuel is injected and supplied. Thereafter, the spray ignites and burns, and a flame develops. Since the pressure rises due to the development of the flame, the flame generated immediately after the ignition becomes higher in temperature due to adiabatic compression and becomes the hottest part of the flame, so that the generation of NO is active. When the flame portion becomes so hot that the generation of NO becomes active, the injection rate is temporarily reduced, and Ano performs a sub-injection aiming at the high-temperature flame portion, and supplies the fuel spray. The hot flame part is cooled and the temperature of this part is rapidly lowered.

(Effects) The method for reducing nitric oxide of an internal combustion engine according to the present invention has the effects described above, and thus has the following effects. In other words, the high-temperature flame portion generated by the main injection is rapidly cooled by the fuel spray supplied by the sub-injection to lower the temperature, thereby suppressing NO generated from the high-temperature flame portion. Since this part is at a high temperature and the generation of NO is most active, the effect of reducing NO is remarkable.

Further, the cooling of the flame is performed locally, and the other flame portions do not lower in temperature, so that the thermal efficiency does not decrease.
Further, the fuel is supplied by the sub-injection, and the introduction of air into the spray is activated by the injection energy, so that the fuel and the air are sufficiently mixed, and the generation of soot is suppressed. Subsequent combustion becomes rapid, there is no deterioration in fuel efficiency, and the emission of unburned fuel is small.

[Description of Another Invention] (Configuration) A nitric oxide reducing device for an internal combustion engine according to a second aspect of the present invention is a reciprocating internal combustion engine formed by a piston, a cylinder head, and a cylinder block. A fuel injection valve communicating with the combustion chamber and a fuel supply source containing light oil or gasoline in the combustion chamber; and first fuel supply means for performing main fuel injection from the fuel injection valve; The injection rate is temporarily reduced from the fuel injection valve into the combustion chamber, and then, subsequent to the main injection, a secondary injection is performed in which the injection rate is increased from the injection rate once decreased among the injection rates of the main injection. The second fuel supply means and the start timing of the injection by the second fuel supply means are set to the initial flame generated by the main injection and having a higher temperature than the other flame portions. Wherein a fuel spray of secondary injection provided fuel supply apparatus for setting the timing for injecting feed configuration of the parts.

(Operation) With the above configuration, the apparatus for reducing nitric oxide of an internal combustion engine of the present invention has the following operation.

When the piston rises near the top dead center at the end of the compression stroke, the pressure and temperature increase due to compression. At that time, the main injection is performed from the fuel injection valve facing the combustion chamber, and the fuel is injected and supplied. Thereafter, the spray ignites and burns, and a flame develops. Since the pressure rises due to the development of the flame, the flame generated immediately after the ignition becomes higher in temperature due to adiabatic compression and becomes the hottest part of the flame, so that the generation of NO is active. When the temperature of the flame becomes high enough to generate NO, the injection rate is temporarily reduced to reduce the generation of flame near the nozzle and lower the temperature of this part. Thereafter, sub-injection is performed with the aim of the high-temperature flame portion, the high-temperature flame portion is cooled, and the temperature of this portion is rapidly lowered.

(Effects) Since the apparatus for reducing nitric oxide of an internal combustion engine of the present invention has the above-described effects, it has the following effects. In other words, when the temperature becomes so high that the generation of NO becomes active, the injection rate is once decreased to reduce the occurrence of flame near the injection port, thereby lowering the temperature of this portion. Further, the high-temperature flame portion generated by the main injection is rapidly cooled by the fuel spray supplied by the sub-injection to lower the temperature, thereby suppressing NO generated from the high-temperature flame portion. Since this part is at a high temperature and the generation of NO is most active, the effect of reducing NO is remarkable.

The cooling of the flame is performed locally, and the temperature of other flame portions does not decrease, so that the thermal efficiency does not decrease.
Further, the fuel is supplied at a high injection rate by the sub-injection, the injection energy is large, and the air introduction into the spray becomes active, so that the fuel and the air are sufficiently mixed, and the generation of soot is suppressed. Subsequent combustion becomes rapid, there is no deterioration in fuel efficiency, and the emission of unburned fuel is small.

(Structure of the Third Invention) The nitric oxide reducing device for an internal combustion engine according to the present invention according to the third invention of the present invention is a reciprocating device formed by a piston, a cylinder head and a cylinder block. A combustion chamber of a dynamic internal combustion engine, and a fuel injection valve communicating with a fuel supply source containing light oil or gasoline in the combustion chamber;
A first fuel supply means for performing main fuel injection from the fuel injection valve; and temporarily decreasing the injection rate from the fuel injection valve into the same fuel chamber as the main injection, and thereafter, following the main injection, the main fuel injection means. A second fuel supply means for performing a secondary injection for increasing the injection rate from the injection rate once decreased among the injection rates of the injection, and a start timing of the injection by the second fuel supply means after the compression top dead center. The fuel supply device is set at a predetermined time between 3 ° and 20 °.

The fuel supply device may include, for example, a fuel injection valve,
A fuel injection valve which is composed of two cams for driving a plunger for feeding fuel and a phase setting device for setting the phase of both cams, or which is electrically driven; A drive circuit for generating an injection drive signal and a sub-injection drive signal having a phase relationship with respect to the main injection drive signal can be provided.

(Operation) The nitric oxide reducing device for an internal combustion engine according to the present invention performs a main injection by injecting a predetermined amount of fuel by a first fuel supply means, ignites and combusts, temporarily reduces an injection rate, and thereafter Increasing the injection rate subsequent to the main injection,
Secondary injection is performed by injecting a predetermined amount of fuel from the second fuel supply means. Further, by setting the start timing of the injection by the second fuel supply means to a predetermined timing between 3 ° and 20 ° after the compression top dead center, the flame generated by the main injection can be set to the secondary side. It has the effect of cooling by the fuel spray of a simple injection.

[Embodiment] A method and an apparatus of the present invention will be described based on an embodiment applied to a diesel engine and a gasoline engine. In the first embodiment, as shown in FIGS.
A IDI diesel engine E ₁ having a combustion chamber as a vortex chamber 2. The diesel engine E ₁ has a recess 4 in the piston 3, to form a main combustion chamber 5 by this and the cylinder head 1 and the cylinder block 7. The cylinder head 1 has a tortuous swirl chamber 2, and the main combustion chamber 5 communicates with a communication hole 6.

In the diesel engine E ₁ , as the piston 3 rises during the compression stroke, the air in the main combustion chamber 5 flows into the swirl chamber 2 through the communication hole 6 and generates a swirling flow in the direction of the arrow in the figure. Let it.
The diesel engine E ₁ is the injection nozzle 8 of the fuel injection valve of FIGS. 3 and 4 s shows a fuel supply system as will be disposed only one on the swirl chamber 2.

This diesel engine E ₁ has an injection system as shown in FIG. 4 for performing the above-described sub-injection before the main injection (normal normal injection) by the injection nozzle 8 is completed. That is, the injection pumps 9 and 10 have two sets of plungers (not shown). One plunger is used for main injection, the other plunger is used for sub-injection. To change. The plunger outlet high-pressure fuel pipe 11 is connected to one and guides high-pressure fuel to the injection nozzle 8. Then, the diesel engine E ₁ is two sets to the pump drive shaft 12 which is driven at half the speed by these crankshaft plunger injection pump 9 and 10, is drivingly connected. Adjustment of each main or sub injection amount is performed by a rack as in a normal diesel engine. Each of the injection pumps 9 and 10 has a timer incorporated therein, and the main injection pump 9 is set in a range of 15 ° to 0 ° before the start of discharge (start of injection) before the top dead center depending on operating conditions (load, rotation speed). Has been adjusted. The timer of the sub-injection pump 10 is similarly adjusted within a range of 5 ° to 20 ° past the top dead center. Further, since the main injection and the sub-injection partially overlap the fuel injection engine, the fuel injection from the injection nozzle 8 is continuously performed.

The first embodiment having the above-described structure is a diesel engine E
_{When the} pressure ₁ reaches 15 ° to 0 ° before the top dead center at the end of the compression stroke, oil is supplied from the main injection pump 9 to the injection nozzle 8, and as shown in FIG. An injection is made.

Ignition of the main injected fuel occurs at the tip or both sides of the spray as shown in FIG. 6, and spreads along with the air vortex.
There is a high temperature area near the flame tip, and the gas temperature is high.
Generates large amounts of NO. This NO generation mechanism is based on the above-mentioned reaction formulas (1), (2), and (3) of Zeldovich.
This is the part that can be explained. And with the passage of time, the seventh
As shown in the figures, the flame spreads and is swirled, and when it passes the top dead center, the flame makes one round. As a result of the combustion-pressure increase accompanying the main injection, gas starts to be injected into the main combustion chamber 5 through the communication hole 6, but the flame is further developed because the fuel injection is continued.

Next, a sub-injection is performed at the flame tip 5 to 20 ° past the top dead center. In this injection, the fuel spray is instantaneously supplied at a high injection rate to the high-temperature region near the flame front, and the flame temperature can be lowered by the heat of vaporization of the fuel spray.
FIG. 1 shows a comparison of high-temperature flame ratios. As shown in FIG. 1, it can be seen that the present embodiment indicated by black circles has less high-temperature flames at 1900 ° C. or higher than the base engine indicated by triangles. That is, since the NO generation mechanism strongly depends on the flame temperature as shown by the above-mentioned Zelditch reaction equation, the sub-injection can effectively suppress the generation of NO by cooling the high temperature portion of the flame.

The sub-injection spray evaporates instantaneously and mixes with high-temperature oxygen and chemically active unburned gas, and the strong mixing energy of the sub-injection promotes the introduction of air into the flame. Immediately after the flame has extinguished, a new flame is created and the flame burns rapidly. At this time, since the piston is descending and its speed is gradually increasing,
The increase in the temperature of the flame is suppressed by the volume expansion, and the temperature rise is small and the generation of NO is small despite rapid combustion. As described above, the high-temperature portion of the flame generated by the main injection is cooled by the sub-injection, and thereafter, the fuel of the sub-injection is efficiently burned by rapid combustion to reduce smoke emission, and the fuel consumption and unburned hydrocarbon emissions are increased. It has an excellent effect of reducing NO.

FIG. 2 is an example of the result of applying the present invention to a swirl chamber type diesel engine and confirming the effect. The engine has a bore of 83 mm and a stroke of 85 mm, and the injection quantity per stroke at full load is about 40 mm ³ . The illustrated state shows a state of about 1/2 load. As shown in Fig. 2, normal injection (main injection) starts at 6 ° before top dead center and ends at TDC, and the injection amount is 10mm ³ / s
t. The amount of sub-injection is 1/2 mm of the main injection and 5 mm ³ / st, and the total injection amount is 15 mm ³ / st. At this time, the variation of the average effective pressure (Pe) and the change of the smoke emission concentration (S) were examined as representative values of the increase and decrease (decrease rate) of NO and the engine performance by changing the timing of the sub-injection. The timing of sub-injection on the horizontal axis, NO, S and
The increase / decrease of Pe is shown, and the line of 1.0 corresponds to the case where the same operation as a normal diesel engine having only main injection is performed.

The start and end timings of the main injection are fixed, and the timing of the sub-injection is changed.

As shown in FIG. 2, the sub-injection timing is 3 to 5 after top dead center.
゜ reduces NO, and 10 ゜ to 15NO minimizes NO. This is because the above-described flame cooling is effectively performed.

Although the timing of the sub-injection has passed the top dead center, the gas temperature at this time is higher than the gas temperature 700 to 800 K at the start of the main injection, and
Since the temperature is up to 2500 K, the ignition delay is short, and in addition, the combustion proceeds rapidly because mixing with highly reactive combustion products proceeds, and Pe is hardly reduced. Further, if the timing of the sub-injection is delayed, the high-temperature portion of the flame is not properly cooled, so that the NO reduction tendency is worsened. Pe also decreases after burning. Also, the tendency of the smoke density S to decrease is reduced.

When the engine is not loaded, the amount of injected fuel is small, the excess air ratio λ is large, and the combustion temperature is low. I do.

On the other hand, at the time of full load, the timing of the sub-injection may be almost the same as the case of light load. This is because the time when the high temperature portion of the flame of the main injection moves to the injection valve orifice position is almost the same regardless of the load. In this case, the sub-injection amount increases, but the subsequent combustion is rapid, so that the smoke emission concentration S is reduced and Pe is not significantly reduced.

The sub-injection amount at no load (the fuel injection amount after the timing at which the injection rate becomes a minimum) and the sub-injection timing (the timing at which the injection rate becomes a minimum) are 0.05q _s / q _max 0.1 (q _s sub injection amount mm ³ st, weight total fuel injection in the q _max full load mm ³ / st) t _s (secondary injection timing), it is effective 3 ° to 10 DEG after top dead center. In the case of full load, 05q _s / q _max 0.33 t _s is effective in the range of 10 ゜ to 20 ゜ after top dead center, and the optimum value is 0.08q _s / q _max 0.2, and t _s is 10 ゜ to 15 ゜.

In consideration of the entire operating load range from no load to full load, the start timing of the sub-injection is 3 ° to 20 ° after the top dead center.

The method and apparatus of the present invention are not particularly inconvenient as long as the engine has an injection nozzle in a combustion chamber as an engine type, and can be applied to IDI diesel, DI diesel, and direct injection spark ignition engines.

The timing of the sub-injection and the injection amount are means for adjusting the flame cooling portion and the degree of cooling, and the optimum adjustment range is as described above.

With such a new combustion method and apparatus, NO can be reduced. The reduction rate reaches 30% or more, and the smoke emission concentration is also reduced by 30% or more at the same time by rapid combustion by sub-injection. It has a remarkable function and effect.

The first embodiment is an extremely effective method and apparatus without increasing the fouling, smoking and abrasion associated with the conventional EGR. In addition, combustion noise of the diesel engine E ₁ of the first embodiment, it is well known to correlate with patterns of the combustion chamber of the fuel heating time course. That is, the lower the heat generation peak, the lower the noise. In the present embodiment, by forming two peaks (maximum values) in the fuel injection rate, the heat generation peak is reduced, and the noise is reliably reduced. This is more remarkable at low speed and low load when the ratio of the sub injection amount to the total injection amount is large. FIG. 8 shows the calculation of the heat generation progress dQ / dθ from the pressure measurement result in the main combustion chamber 5. The amount of main injection plus sub-injection in the case of normal regular injection and in the case of performing sub-injection is the same. When the sub-injection is performed, the peak of dQ / dθ decreases, and dQ / dθ in the latter half increases, and as a result, the area in FIG. 8, that is, the calorific value hardly changes.

Next, in general, a diesel engine has a higher compression ratio, a higher combustion maximum pressure, and a sharper dQ / dθ progress than a gasoline engine, so that the torque fluctuation during one cycle is large. In the case of a vehicle engine such as an engine body or a transmission, this causes vibration of the drive system. FIG. 9 shows the torque fluctuation situation during one cycle. Compared with a gasoline engine, a diesel engine fluctuates more at the same average torque (so-called shaft torque). When the sub-injection is performed, the heat generated by the sub-injection is added in the latter half of the combustion and the peak is reduced as described with reference to FIG. It has excellent effects.

An injection system as a fuel supply device is provided inside the injection nozzle 8 as shown in FIG. 4, and lifts a needle valve seated on a valve seat of an injection hole by a valve spring by fuel pressure. However, not only the mechanical type that performs fuel injection,
As shown in FIGS. 10A and 10B, the electromagnetic solenoid 13 is operated in accordance with the operation state of the internal combustion engine, the needle valve is lifted by the electromagnetic force, and an electric type such as a pressure-accumulation type electromagnetic injection valve that performs fuel injection is used. The same operation and effect as described above can be obtained.
In FIG. 10, reference numeral 14 denotes a fuel pipe, one end of which communicates with the fuel passage of the electromagnetic injection valve 15, and the other end of which communicates with the hydraulic pump P via the accumulator 16 and the check valve 17.

Next, a second embodiment is an example applied to a direct injection diesel engine E ₂ as shown in FIG. This diesel engine E ₂ has a combustion chamber having a recess 19 of a predetermined volume in a piston 18.
At 20, the injection nozzle 21 is a Hall valve with multiple injection holes. The injection system has the same type as that of the first embodiment, but differs from the first embodiment in that the single-hole pintle valve or the throttle valve is used. In the combustion chamber 20, a swirl at the time of suction remains as shown by an arrow in the drawing, and there is a swirling flow. In this case, four to five fuel injections injected from the injection nozzle 21 are radially injected into the recess 19, and subsequently, after the sub injection,
Cooling of the high-temperature flame is performed for each of the tubes, as in the first embodiment described above.

That is, four to five radially sprayed fuel sprays are ignited and burned, and are caused to flow in the circumferential direction of the recess by the swirling flow formed in the recess 19, and the other fuel spray downstream of the swirling flow is Rotate to a position where it interferes with spraying. The flame rotated to this position is a flame generated by the combustion immediately after the ignition, and as described in the first embodiment, the generation of NO is active at a higher temperature than the other flames. Therefore, a sub-injection is performed to this high-temperature flame, and fuel is supplied instantaneously and locally at a high injection rate, thereby rapidly lowering the temperature of the high-temperature flame portion and suppressing generation of NO. In addition, since the turbulence is generated by the injection energy of the sub-injection and the introduction of air into the flame can be promoted, soot generation can be suppressed, and there is no delay in combustion due to the sub-injection, so that fuel consumption does not deteriorate. In this way, the second
Examples to direct injection diesel engine E ₂ can be effectively performed, achieves substantially the same effects as the first embodiment.

Considering the case of the diesel engine shown in the first embodiment and the second embodiment, it is theoretically sufficient to inject fuel according to the degree of flame cooling, but the injection amount of the sub-injection is too small. And atomization is bad, and it becomes a dripping state like a later person, causing soot generation. In general, a single spray requires 2 mm ³ or more to ensure atomization. Also, the lower the speed of the engine, the lower the pressure of the injection pump and the worse the atomization,
The minimum injection amount increases slightly to ensure atomization.

In the case of a diesel engine, although fuel injection differs depending on operating conditions (load and rotation speed), main fuel injection is performed at 15 ° to 5 ° before top dead center, and subsequently sub injection is started at approximately top dead center. .
The ignition of the fuel supplied into the combustion chamber by the main injection occurs several degrees later than the start of injection, starts combustion, and the temperature is 1500 to
Reach 2500K. The high temperature of the flame is cooled by the sub-injection following the main injection, and the temperature is lowered with the expansion due to the lowering of the piston. In order to supply the fuel of the sub-injection to the high temperature part of the flame of the main injection, the timing of the sub-injection is about 5 minutes after the top dead center.
Although it is better to set it to ゜ to 20 ゜, the speed of movement of the high-temperature part of the main injection flame varies depending on the strength of the swirl flow formed in the combustion chamber. is there.

Next, as still another embodiment, as shown in FIGS. 12 and 13, a cylinder for directly injecting gasoline metered by a fuel injection valve 28 into a recess 24 of a combustion chamber 23 and performing a main injection and a sub injection. an inner fuel injection type internal combustion engine E _3, omitted discussed focusing on differences from the embodiment described above, the same portions are denoted by the same reference numerals explained.

The fuel supply device of the piston type gasoline engine E ₃ of the present embodiment
26 is an injection hole that penetrates through the cylinder head 1 and
A so-called impingement type injection valve 28 having an exposed 27 and having the injection system shown in FIG. 10 described above, an air flow meter for detecting the amount of intake air in the intake passage 29 ', and detecting the engine speed. A control unit for outputting a signal for controlling an injection amount of gasoline in accordance with an operating condition of the engine in consideration of an engine cooling water temperature based on a signal of the tachometer, the intake air amount and the engine speed; And a fuel supply device for supplying pressurized gasoline in an amount corresponding to the control signal to the injection valve.

The collision type injection valve 28 has an injection hole 27 directed toward a collision portion CP fixed to a member IM inserted in the valve body VB via a rod member BM.
Gasoline is injected and collided, and the direction of the gasoline is changed from the collision portion CP to inject gasoline in the form of a thin film with a wide injection angle.

The intake valve 29 as an intake mechanism is provided with a shroud 30 for forming a swirling flow in the intake air.

By the way, the piston type gasoline engine E ₃ of this embodiment is
As shown in FIG. 13, an upper part 20 of the piston 31 is provided with an igniter 25 for forming a perfect circular recess 32 in cross section and igniting and burning the fuel spray mainly injected into the cylinder head 1. .

The piston type gasoline engine of the present embodiment having the above configuration
E ₃ is the fuel is mainly injected or sub injection earlier than seen injection timing to a diesel engine E _1, E ₂ described above, and by using a relatively wide divergence angle and good collision type injectors of atomized fuel spray Extends over substantially the entirety of the recess 32. Then, due to the suction swirl generated by the shroud 30 of the intake valve 29, the fuel spray related to the main injection turns and approaches the TDC while turning, and the swirl of a strong mixture is converged in the recess 32 at the upper part of the piston while evaporating and mixing. You.

[0058] Near the TDC, ignited by the ignition device 25, the flame is
It gradually spreads while being swept away by the swirling flow inside. Also in this case, as in the other embodiments, the flame in the early stage of combustion has the highest temperature and the generation of NO is active. The sub-injection is performed when the high-temperature flame portion has swirled near the injection port of the injection valve 28, and the high-temperature flame is instantaneously and locally cooled by the high-injection-rate fuel spray. As a result, the generation of NO is suppressed, and the emission amount of NO is reduced.

[Brief description of the drawings]

FIG. 1 is a diagram comparing the progress of the development of a high-temperature flame according to the present invention and the prior art internal combustion engine at a flame ratio of 1900 ° C. or higher, and FIG. 2 is a diagram of a vortex chamber type diesel engine according to an embodiment of the present invention. N
FIGS. 3 to 7 are schematic diagrams showing a diesel engine with a swirl chamber according to the first embodiment of the present invention, and FIGS. 8 and 9 are diagrams showing the first embodiment. Diagram showing heat generation progress and torque fluctuation status in the example, respectively, FIG.
The figure is a schematic view showing another injection system of the fuel supply device, and FIGS. 11 and 12 are sectional views showing the second embodiment and other embodiments of the present invention, respectively. In the figure, 8, 15, 21, 28 ... injection nozzle, 1 ... cylinder head, 2 ... swirl chamber, 3 ... piston, 6 ... communication hole, 7 ... cylinder block, 9 ... injection for main injection Pump, 10: Injection pump for sub-injection, 11: Fuel pipe

Continuation of the front page (51) Int.Cl. ⁷ Identification mark FI F02D 41/34 F02D 41/34 E Joint panel Referee Susumu Funaki Referee Nao Yamaguchi Referee Eiaki Kiyota (56) References JP 62-70645 (JP, A) JP-A-62-150066 (JP, A) JP-A-62-225759 (JP, A) JP-A-63-195375 (JP, A) JP-A-62-142857 (JP, A) JP-A-59-165856 (JP, A) JP-A-52-50403 (JP, A) JP-A-2-27117 (JP, A) JP-A-61-149767 (JP, U) JP-A-61-130762 (JP, A) JP, U) JP 48-8935 (JP, B1)

Claims (6)

(57) [Claims] 1. A reciprocating internal combustion engine formed by a piston, a cylinder head and a cylinder block communicates with a fuel supply source containing gas oil or gasoline in a combustion chamber of a reciprocating internal combustion engine. During the stroke, a main injection for injecting a predetermined amount of fuel is performed to cause ignition and combustion, and the injection rate is once reduced, and thereafter, following the main injection, the injection rate is reduced from the injection rate once reduced among the injection rates of the main injection. The fuel injection device performs a secondary injection that supplies a predetermined amount of fuel at a predetermined time from the fuel supply device into the same combustion chamber as the main injection at the same time as the main injection. The flame portion having a higher temperature than the other flame portions is cooled by the fuel spray of the secondary injection, and the combustion produces nitrogen oxide. Nitrogen reduces oxidation process for an internal combustion engine, characterized in that as it allowed suppress the formation to reduce the emission of said nitric oxide in the medium. 2. A fuel injection valve communicating with a combustion chamber of a reciprocating internal combustion engine formed by a piston, a cylinder head, and a cylinder block, and a fuel supply source containing gas oil or gasoline in the combustion chamber. A first fuel supply means for performing a main fuel injection from the fuel injection valve, and temporarily decreasing an injection rate from the fuel injection valve into the same combustion chamber as the main injection, and thereafter, following the main injection, the injection rate of the main injection The second fuel supply means for performing a secondary injection that increases the injection rate from the once reduced injection rate, and the ignition start timing of the injection by the second fuel supply means is determined by the ignition generated by the main injection. The fuel supply device is designed to design the timing of injecting and supplying the fuel spray of the secondary injection to a flame portion which is an initial flame and has a higher temperature than other flame portions. Nitrogen oxide reduction system of an internal combustion engine to be. 3. A fuel injection valve communicating with a combustion chamber of a reciprocating internal combustion engine formed by a piston, a cylinder head and a cylinder block, and a fuel supply source containing light oil or gasoline in the combustion chamber. A first fuel supply means for performing a main fuel injection from the fuel injection valve, and temporarily decreasing an injection rate from the fuel injection valve into the same combustion chamber as the main injection, and thereafter, following the main injection, the injection rate of the main injection A second fuel supply means for performing a secondary injection for increasing the injection rate from the once reduced injection rate, and setting the start timing of the injection by the second fuel supply means to 3 ° to 20 ° after the compression top dead center. 3. A nitrogen oxide reducing device for an internal combustion engine, comprising a fuel supply device that is set at a predetermined time between ゜ and ゜. 4. The method according to claim 1, wherein the second fuel supply means starts the injection by adding the secondary flame to a flame portion at an early stage of ignition generated by the main injection and having a higher temperature than other flame portions. The apparatus for reducing nitrogen oxides in an internal combustion engine according to claim 3, wherein the timing is set at a time of injecting and supplying a fuel spray of a specific injection. 5. The method according to claim 1, wherein a swirling flow is formed in the combustion chamber. 6. The internal combustion engine according to claim 2, further comprising a swirl flow forming means for forming a swirl flow in said combustion chamber. apparatus.