FR2515260A1 - 2-STROKE INTERNAL COMBUSTION ENGINE AND COMBUSTION ENGINE IGNITION METHOD - Google Patents

Abstract

Two-stroke internal-combustion engine having a combustion chamber and a scavenging port, which opens into the combustion chamber. If the engine is working under low load, and consequently considerable amounts of uncombusted and only partially combusted fractions and oxygen remain in the combustion chamber, fresh air is introduced at low speed from the scavenging port into the combustion chamber, so that it does not disturb the residual gas in the combustion chamber. As a consequence of this, the oxidation of the uncombusted and partially combusted fractions continues without interruption during the expansion stroke and the compression stroke and a self-ignition of the remaining gases is induced at the end of the compression stroke. The self-ignited residual gas brings about an ignition of fuel which is injected into the combustion chamber by means of an injection device.

Description

2-TEMP INTERNAL COMBUSTION ENGINE
COMBUSTION IGNITION SYSTEM AND METHOD APPLICABLE TO THE ENGINE.

 The present invention relates to a two-stroke internal combustion engine of the fuel injection type, as well as an ignition-combustion method applicable to this type of engine.

 As is well known to those skilled in the art, a spark ignition type 2-stroke engine in which fuel is injected into the engine cylinder has the advantage that the decarburizing amount flowing Exhaust ducting can be significantly reduced, resulting in good thermal efficiency and good conditions for emissions of noxious substances in the exhaust when the engine is operating under average load or strong. However, when operating a 2-stroke engine of this type under a light load, it is difficult to maintain a stable combustion. As a result, in a conventional 2-stroke engine, to obtain a stable combustion when the engine operates under a heavy load, the engine is supplied with a rich air-fuel mixture, or the start of combustion is strongly retarded by acting on the ignition point. As a result, in a conventional 2-stroke engine, despite the fuel injection into the engine cylinder, there are disadvantages in that when the engine is operated under a light load, the thermal efficiency is reduced. and, in addition, the amount of harmful substances, such as carbon monoxide and hydrocarbons, in the exhaust gas is increased.

 The object of the invention is to provide an ignition-combustion method and a 2-stroke engine which makes it possible to considerably increase the thermal efficiency and to reduce the quantity of harmful substances in the exhaust gases, compared to a 2-stroke engine of known type, when the engine operates under a low load.

 In accordance with the present invention, there is provided an ignition-combustion method for an internal combustion engine comprising a combustion chamber, a fuel injector disposed in the combustion chamber, an air inlet for introducing fuel into the combustion chamber. fresh air in the combustion chamber and an exhaust gas outlet for discharging exhaust gases from the combustion chamber, said method of discharging the exhaust gases from the combustion chamber through the combustion chamber; - diary of said outlet port, while retaining a large amount of residual gas, containing unburned components, incompletely burned components and oxygen, in the combustion chamber; uniformly supplying the combustion chamber with fresh air from said air inlet while suppressing disturbances of the residual gas for further oxidation reaction of unburned components and incompletely burned components; injecting fuel into the combustion chamber from the fuel injector to form a fuel mixture consisting of fuel and fresh air; and compress the. residual gas and said fuel mixture in the combustion chamber to accelerate the oxidation reaction and to produce self-ignition of the residual gas, this self-ignited residual gas in turn producing an ignition of said fuel mixture.

 In addition, according to the present invention, there is provided an ignition-combustion method for a two-stroke engine comprising a combustion chamber, a fuel injector placed in this combustion chamber, a sweeping orifice opening into the chamber. combustion engine, an exhaust port opening into the combustion chamber, a crankcase housing containing an inner chamber and a transfer passage providing the connection of the sweep orifice to the inner chamber of the crankcase, said method. comprising: supplying fresh air to the inner chamber of the crankcase; compressing the fresh air in said crankcase chamber and discharging exhaust from the combustion chamber through the exhaust port while retaining a large amount of residual gas containing unburned components , incompletely burned components and oxygen, in the combustion chamber; channel the fresh air in the crankcase chamber into the transfer passage; limit the speed of fresh air flowing into the transfer passage when the engine is operating under partial load; uniformly supplying the combustion chamber with fresh air from the purge port while suppressing disturbances of the residual gas for further oxidation reaction of unburned components and incompletely burned components; injecting fuel into the combustion chamber from the fuel injector to form a fuel mixture consisting of fuel and fresh air; compressing the residual gas and the fuel mixture in the combustion chamber to accelerate the oxidation reaction and to produce self-ignition of the residual gas, the self-ignited residual gas in turn igniting said combustible mixture.

 Further, in accordance with the present invention, there is provided a two-stroke internal combustion engine, comprising: a crankcase housing containing an inner chamber; a cylinder block mounted on the crankcase and provided with a cylindrical bore; a piston movable alternately in said cylinder bore, said piston and said cylinder bore defining a combustion chamber; a fuel injector disposed in the combustion chamber for injecting fuel into this chamber; a transfer passage having a purge port at one end and an air inlet at the other end, said purge port and said air inlet respectively opening into said combustion chamber and into the inner chamber of the housing crankshaft so as to transfer fresh air in said inner chamber to said combustion chamber; an exhaust passage having an exhaust port that opens into the combustion chamber to discharge exhaust from said combustion chamber; and throttling means disposed in said transfer passage for limiting the rate of fresh air flowing in said transfer passage when the engine is operating under partial load.

 In accordance with the present invention, to improve combustion when the engine is operating under light load, by holding a large amount of unburned components, incompletely burned components and oxygen in the residual gas produced in the combustion chamber in the combustion chamber. previous cycle, and maintaining the residual gas at a high temperature while removing the disturbances of the residual gas and ensuring its cooling, these disturbances being caused by a sudden entry of fresh air charge, the production of a strong flow injection and the powerful jet flowing between the main combustion chamber and the pre-combustion chamber, it is arranged that the oxidation reaction proceeds continuously in the residual gas during the period between the beginning of the time of relaxation and the end of the compression time, even after completion of the combustion in the previous cycle.

The continuous oxidation reaction then causes a self-ignition of the gas in the combustion chamber and then the self-ignition of this gas in the combustion chamber causes ignition of the mixture of fuel and fresh air located in the combustion chamber.

 In the combustion process according to the invention which has been described above, even after the termination of the main combustion producing a large amount of heat, a uniform oxidation reaction is produced in place of a combustion. fast, continuously in the residual gas during the relaxation time, the exhaust-exhaust gas exhaust time, and the initial portion of the compression time.

The uniform oxidation reaction occurring in the residual gas is rapidly accelerated in relation to an increase in the density and temperature of the residual gas during the compression time and causes a self-ignition of the residual gas. which in turn produces an ignition of the mixture of fuel and fresh air. In such a combustion process, since a large quantity of inert residual gas is present in the combustion chamber, a uniform and stable combustion is produced in each cycle, but it does not produce an extraordinary combustion, causing a sudden increase in pressure and caused by superficial inflammation, pre-ignition, auto-ignition in a diesel engine and auto-ignition causing a knock in a combustion engine. petrol. In addition, the mixture of fuel and fresh air that diffuses into a large amount of residual gas and mixes with it is not completely burned in the residual gas and remains in the form of unburned components and incompletely burned components.

These unburnt components and these incompletely burned components continuously cause an oxidation reaction with the oxygen in the residual gas during the exhaust-scan time and during the compression time of the next cycle and thus cause an auto -Inflammation in the next cycle.

 As mentioned above, in the present invention, although fuel is injected into the engine cylinder and then self-ignition occurs, self-ignition occurring in accordance with the present invention is clearly different from that occurring in a conventional diesel engine with respect to the following points.

So, in a diesel engine, carburetor is. injected for a crankshaft angle close to the top dead center position at the end of the compression times. In contrast, in accordance with the present invention, fuel injection is initiated between a crankshaft angle (60 to 700 before the bottom dead position) for which the exhaust and scan operation is started and an angle of crankshaft preceded by 50 top dead center, and fuel injection is mainly performed during the initial phase and the intermediate phase of the compression time.

Further, in accordance with the present invention, the engine compression ratio is relatively low and has a value less than 12: 1.

Also, according to the present invention, it is impossible to start the engine without using a spark plug or a glow plug, regardless of the temperature of the air entering the engine cylinder.

 Another engine in which self-ignition occurs is the Lohman engine. However, the compression ratio used in the Lohman engine is quite different from that used in the present invention and, therefore, the auto-inflammations produced in the Lohman engine is quite different from that occurring according to the present invention.

 On the other hand, in a 2-stroke engine with pre-mixing charge (a carburettor engine), the idea of causing self-ignition by using an active thermoatmospheric combustion system in which it is intended a relatively long transfer passage to promote mixing of the air-fuel mixture, vaporization of the air-fuel mixture and production of radicals is well known (Japanese Patent No. 5638766 and Japanese Patent Application No. 54-289160.

However, the feature of the present invention is that fuel is injected into the engine cylinder and uniform and stable combustion is performed in each cycle such that atomized fuel, fresh air entering the cylinder from the scavenging orifice and the residual gas at high temperature, which has been produced in the preceding cycle and remaining in the cylinder, are con cluded so that they are laminated and suitably mixed together by atomized fuel diffusion. As a result, the car
inflammation occurring according to the present invention is
markedly different from the self-inflammation caused by a mixture of
charge pre-mixed with the residual gas, as in the combustion system
thermoatmospheric active.

 Further, in the above-mentioned 2-stroke and charge premix engine, flue gas scavenging is performed by mixing fuel and air. In contrast, according to the present invention, flue gas scavenging is performed solely by air, mainly immediately after the scavenging opening, and fuel is injected into the cylinder at a desired instant, regardless of the flushing operation.

As a result, it is possible to prevent the atomized fuel in the cylinder from leaking into the exhaust port. Furthermore, since a diffusion of the atomized fuel into the fresh air and into the high temperature residual gas is easily controlled and simultaneously a mixture of the atomized fuel with the fresh air and the residual gas is also easily controlled, Controlled combustion can be achieved by lamination of atomized fuel, fresh air and residual gas.

With regard to one of the effects obtained by causing said controlled combustion, for example by starting the fuel injection into the cylinder while the crankshaft angle is between 90 "before the top dead center position and 50" before the crank angle is position of high dead point in an ignition-combustion system according to the present invention, it is possible to significantly reduce the lower limit of the range of light loads in which a stable self-ignition can be performed, compared with the motor 2 and in the case where fuel is injected into the cylinder for a crankshaft angle close to the top dead center position, or when a sweeping is carried out by the pre-mixed charge when the engine is operating under a light load, when the discharge rate is extremely low, since a fuel mixture diffuses excessively in a large amount During the compression time, the density of the combustible mixture becomes small and the result is that self-ignition is less easily produced at a crankshaft angle close to the top dead center at the end of the compression time.

In contrast, in accordance with the present invention, starting the fuel injection into the cylinder while the crankshaft angle is between 90 before the top dead center position and 50 "before the top dead center position, when the engine reaches the end of the compression time, the fuel mixture is kept in a state of diffusion and mixing which is optimal for producing auto-ignition and, simultaneously, the fuel mixture is maintained at a temperature which is optimal for producing a car -Inflammation, resulting in a stable autoinflammation.

 Other objects and advantages of the present invention will appear on reading the following description and accompanying figures, given for illustrative but not limiting.

 Figure 1 is a perspective view of an embodiment of a 2-stroke engine according to the present invention and a part of which is indicated in broken view.

 Figure 2 is a side sectional view of the engine of Figure 1.

Figure 3 is a sectional view taken on the line III-III of the
Figure 2

 Figure 4 is a plan view of the sweep control valve.

 Figure 5 is a perspective view of another embodiment of a 2-stroke engine according to the present invention, a part of which is indicated in broken view.

 Figure 6 is a sectional view of the motor shown in Figure 5.

Figure 7 is a sectional view taken on the line VII-VII of the
Figure 6.

 Figure 8 is a diagram showing the start time of injection based on the load.

 Figure 9 is a motor pressure indicator diagram according to the present invention (such a diagram is called the indicator diagram).

 Figure 10 is an indicator diagram of a conventional 2-stroke engine.

 Figure 11 is a diagram giving the specific fuel consumption.

 Figure 12 is a chart showing the concentration of carbon monoxide.

 Figure 13 is a diagram showing the concentration of hydrocarbons.

 Figure 14 is a diagram giving the specific fuel consumption.

Figure 15 is a diagram giving the concentration of carbon monoxide and
Figure 16 is a diagram showing the concentration of hydrocarbons.

Figures 1 to 3 show a first embodiment showing the case where the present invention is applied to a 2-stroke engine of the type
Schnürle. In Figures 1 to 3, there is designated by 1 a crankcase,
2 a cylinder block mounted on the crankcase 1, 3 a cylinder head fixed on the cylinder block, and 4 a piston with a top face
approximately flat and movable alternately in a bore
5 formed in the cylinder block c; a combustion chamber has been designated
formed between the cylinder head 3 and the piston 4, by 7 a crankshaft, by 8 a balancing counterweight fixed on the crankshaft 7, and by 9 a connecting rod connecting the piston 4 balancing counterweight 8.The cylinder head 3 has a wall concave interior 10 and a spark plug or a glow plug 11 is placed in the center of the concave inner wall 10.

In addition, a fuel injector 12 is mounted on the concave inner wall 10 in a position close to the spark plug 11. This fuel injector 12 is connected via a conduit 13 to an injection pump fuel 14 which is driven by the crankshaft 7 via a belt 15, -the injection operation performed by the injector 12 being controlled by the pump 14, as will be described in the following. As indicated in FIG. 2, an inlet orifice 16, which is alternately closed and open by the piston 4, is formed in the inner wall of the cylinder bore, and is connected to an intake pipe 17. A throttle valve 18, supported by an axis 19, is mounted in the intake pipe 17, and an arm 20, fixed on the axis 19 of the throttle valve, is connected to a manual lever (not shown), such as an accelerator. As the valve moves upward and clears the inlet port 16, ambient air is introduced into the crankcase 1 in a conventional manner. Then, when the piston 4 descends and closes the inlet port 16, the operation of compressing the air introduced into the crankcase 1 is primed.

As shown in Figures 1 and 2, an exhaust port 21, which is alternately open and closed by the piston 4, is provided in
the inner wall of the cylinder bore 5 and is connected to an exhaust pipe 22. An exhaust control valve 23, supported by a rod 24, is disposed in the exhaust pipe 22 and an arm 25 , fixed on the valve stem 24, is connected to the aforementioned manual lever so that the opening degree of the exhaust control valve 23 is increased corresponding to an increase in the degree of opening
butterfly 18.

As shown in Figure 3, two scanning orifices 26, which are
alternatively open and closed by the piston 4, are provided in the
inner wall of the cylinder bore 5 and they are connected to the volume
inside the crankcase 1 through passages
27 corresponding transfer that extend through the cylinder block 2
and the crankcase 1. In addition, as shown in Figures 1 to 3
a sweep control valve 28, formed by an annular plate,
is rotatably mounted between the upper face of the crankcase 1 and the underside of the cylinder block 2. As shown in FIG. 4, the sweep control valve 28 has two orifices 29 which can be connected with the trans passes. , 27 corespondans. When the sweep control valve 28 is in the position shown in Figure 4 (a), each of the orifices 29 is completely aligned with the corresponding transfer passage 27 and, therefore, at that moment, the passage section of the orifices 29 is maximum. When the sweep control valve 28 has been rotated into the position indicated on the
4 (b), each of the orifices 29 is partially aligned with the corresponding transfer passage 27 and, as a result, the passage section of the orifices 29 is reduced.The scanning valve 28 comprises an arm 30, which forms a single and same piece with the valve and which is connected to the manual lever mentioned above to rotate the sweep valve 28 so that the passage section of the orifices 29 is increased in connection with an increase in the degree of opening of the butterfly valve. Strangulation 18.

 In operation, when the piston 4 moves downwards and clears the exhaust port 21, burnt gases in the combustion chamber 6 are discharged into the exhaust pipe 22 via the orifice 21. Then, when the piston 4 continues to descend and disengages the sweep orifices 26, the pressurized air inside the crankcase 1 is introduced into the combustion chamber 6, starting from 24 and through the transfer passages 27, and it scans the flue gases in the combustion chamber 6. Fuel is then injected into the combustion chamber 6 by the injector 12, a way which will be described in detail later.

 In the 2-stroke engine shown in FIG. 1, in the case where the engine is operating under a light load, a large amount of the unburnt components and incompletely burned components are contained in the flue gases in the combustion chamber 6 during the time of relaxation. Then, even if the exhaust port 21 is open and then the sweep ports 26 are open, a residual gas having a high temperature and containing a large amount of unburned components and incompletely burned components, remains in the chamber. combustion 6 and, accordingly, the oxidation reaction of the unburnt components and incompletely burned components is carried out continuously.However, in a conventional 2-stroke engine, when the exhaust port 21 is open, and when thereafter the sweeping orifices 26 are open, since a strong disturbance and a violent flow of the residual gas occur in the combustion chamber 6, the oxidation reaction of unburned components and incompletely burned components is interrupted. Nevertheless, according to the present invention, the direction of the sweeping orifices 26 is chosen so that the air coming from these sweeping orifices 26 disturbs as little as possible the residual gas present in the combustion chamber 6. since the passage section of the orifices 29 of the sweeping control valve 28 is small when the engine is operating under a light load, air flowing in the transfer passages 27 is subjected to a pressure drop and, as a result, the air enters the combustion chamber 6 at low speed so that it disturbs as little as possible the residual gas in the combustion chamber 6. In addition, since the degree of opening of the valve 23 is low when the engine operates under a light load, exhausted flue gases in the exhaust pipe 22 are subjected to a pressure drop and, as a result, the flue gases are discharged. the combustion chamber 6 in the exhaust pipe 22 at a low speed, so that they disturb as little as possible the residual gas in the combustion chamber 6. In addiction, in the case where the degree of the exhaust control valve 23 is low, the pulsation pressure of the exhaust gas is prevented from disturbing the residual gas in the combustion chamber 6. Accordingly, according to the present invention, when the engine operates under a light load, since the disturbance and the violent flow of residual gas in the combustion chamber 6 are suppressed, the oxidation reaction of the unburned components and incompletely burned components continues without interruption. The oxidation reaction is accelerated during the compression time and causes self-ignition at the end of the compression time. As a result, the self-ignition causes ignition of the fuel injected by the injector 12 during the compression time.

 Figures 5 to 7 show a second embodiment where components similar to those of Figures 1 to 4 have been designated by the same reference numerals. In this embodiment, as shown in FIG. 6, the inside of the crankcase 1 is connected to the intake pipe 17 via a valve 40 and, as the piston 4 moves upwards, ambient air is introduced into the crankcase 1 through the intake pipe 17 and the valve 40. In addition, in this embodiment, another sweep port 41, which is alternatively closed and opened by the piston 4, is formed in the inner wall of the cylinder bore 5 in addition to a pair of sweeping orifices 26.The sweep orifice 41 is connected, via a passage 42, formed in the cylinder block 2, a recess 43 formed in the crankcase 1 in a position placed around the skirt-shaped portion 2a of the blister 2. As shown in Figures 5 to 7, it is provided in the crankcase 1, in addition to the recess 43, three recesses 44, 45, 46 which are placed in positions located around the skirt-shaped portion 2a.The sweeping orifices 26 are connected to the recesses 44 and 45 via corresponding transfer passages 47 respectively formed in the block 2, and each of the recesses 44 and 45 is always connected to the recess 46 by means of corresponding grooves 48 and 49 formed in the crankcase 1.

In addition, the recess 46 is connected to an air intake port 50, formed in the bottom wall provided inside the crankcase 1, via a transfer passage 51 having a relatively long length and a relatively small cross section. In this embodiment, a shutoff valve, allowing airflow from the inlet port 50 to the recessed portion 46, may be disposed in the transfer passage 51.

 As shown in FIGS. 5 to 7, three air inlets 52, 53 and 54, which are respectively associated with the recessed portions 43, 44 and 45, are formed in the skirt portion 2a, and a valve Scanning control ring 55 is rotatably mounted in the skirt portion 2a. This sweep valve 55 has three orifices 56, 57 and 58 which can be aligned respectively with the air intake orifices 52, 53 and 54. In addition, the sweep control valve 55 comprises a stop 59 forming a single and same piece with it and disposed in the recessed portion 46. The sweep control valve 55 is connected to a manual lever via a cable 60.

 When the engine is running under a light load; all orifices 52, 53 and 54 are closed by the sweep control valve 55.

Accordingly, when the piston 4 disengages the sweep holes 26 and 412 from the pressurized air in the crankcase 1 is channeled to the recessed portions 44 and 45 through the orifice
50, the transfer passage 51, the recessed portion 46 and the grooves 48 and 49, and is then introduced into the combustion chamber 6 from the sweeping orifices 26 and through the passages Accordingly, at this time, air enters the combustion chamber 6 only from the sweeping orifices 26. Since the transfer passage 51 has a relatively large length and a relatively small cross section, such as mentioned above, the air flowing in the transfer passage 51 is subjected to a pressure drop and the result is that the air enters the combustion chamber 6 from the scanning orifices 26 at a low speed . As a result, since a violent flow and a disturbance of the residual gas are suppressed, the oxidation reaction of unburnt components and incompletely burned components continues uninterrupted and consequently causes self-ignition at the end of the reaction time. compression.On the other hand, when the engine runs under a heavy load, the sweep control valve 55 is rotated into the position shown in Figure 7 (b) so that the orifices 56, 57 and 58 of the The sweep control valve 55 is aligned with the respective air intake ports 52, -53 and 54. At this time, pressurized air in the crankcase 1 is directed to the recessed portions 43. 44 and 45 through the pairs of aligned orifices (52,56), (53,57) and (54,58), and it enters the combustion chamber 6 from all the scanning orifices 26 and 41 through the transfer passages 4 2, 47 correspondents. At this moment, the fuel injected by the injector 12 is ignited by the spark plug 11.

Figure 8 shows the time of the start of fuel injection by the injector 12 used in the first and second embodiments.

In FIG. 8, the motor load (%) is plotted on the abscissa, and the crankshaft angle (degrees) on the ordinate. If fuel injection is started in zone A shown in Figure 8, the amount of fuel leaking into the exhaust pipe 22 is increased.

Thus, at this time, since a portion of the fuel injected by the injector Il escapes into the exhaust pipe 22 at the same time as the scavenging air coming from the sweeping orifices 26 and 41, the operation of the engine is similar to that of a conventional two-stroke, pre-charge engine in which pre-mixed fuel and air are introduced into the combustion chamber from the scavenging orifices.

 Areas e, C and D shown in FIG. 8 may therefore be other than those of the present invention. However, in zone B, the fuel injected by the injector 12 diffuses excessively into the residual gas and is therefore excessively mixed with it while, in zone D, the atomized fuel is excessively stratified during the ignition and of combustion. On the contrary, in zone C, a satisfactory diffusion and stratification of the atomized fuel is obtained and, consequently, the instant of injection start, highlighted in zone C, is optimal. On the other hand, although the start of injection demonstrated in zone E in FIG. 8 is capable of producing combustion, a satisfactory diffusion and mixing of the atomized fuel is not obtained, and smoke is produced.

Figure 8 merely highlights a general trend with regard to the start of injection and, therefore, zones A, B, C, DRt
E are modified in correspondence with modifications of the design parameters and engine drive parameters, for example the direction of the openings of the sweeping orifices 26, the power of the injection flow and the vortex movement, the force of penetration of the engine, fuel injected by the injector 12, the spreading angle of the fuel jet, the properties of the fuel, etc.

 Figure 9 shows a diagram-indicator which has been established using an ignition-combustion process according to the present invention.

Figure 9 shows in (a) an indicator diagram of a single
cycle, and in (b) a comb-shaped indicator chart for multiple cycles. On the other hand, Figure 10 shows a diagram indicator obtained using a spark ignition 2-stroke engine and conventional fuel injection type, operating under a low load. In Fig. 10, there is shown in (a) an indicator diagram which is plotted so that the pressure variations of two cycles are superimposed, while in (b) a multi-cycle indicator-indicator has been indicated. . In addition, in FIGS. 9 and 10, the pressure Pet> as abscissa, the crankshaft angle 9 is plotted on the ordinate.

From FIGS. 9 and 10, it can be seen that the combustion according to the present invention is quite different from that of a conventional 2-cycle engine, with regard to the mode of heat release and combustion stability. in each cycle. Thus, the ignition method according to the present invention has characteristics such that the main heat release occurs at a crankshaft angle close to the top dead center position, that the pressure variation dP / dO is small, and that the maximum pressure P in each cycle is almost the same.

 Figures 11 to 13 give the results of experiments carried out using the 370 cm3 motor shown in Figures 1 to 4, while Figures 14 to 16 show the results of experiments carried out using the 370 cm3 motor shown in Figs. Figures 5 to 7.

In FIGS. 11 to 16, the mean effective pressure me (kg / cm 2) is plotted on the ordinate, while the number N of
RPM of the engine. In Figures 11 and 14, the curved lines represent the specific fuel consumption (g / CH.h).

In addition, in Figures 11 and 14, the curve WOT represents a full load curve, which shows that high torque is obtained over a wide range of engine RPM. In addition, Figures 11 and 14 show that, in accordance with the present invention, since fuel is prevented from leaking into the exhaust pipe 22 and since it is possible to burn a lean mixture which is controlled by stratification, can achieve good specific fuel consumption throughout the range of engine operating conditions compared to a conventional engine having a size that is almost the same as that of the engine used in the aforementioned experiments.

 In Figs. 12 and 15, the curved lines indicate the concentration (%) of carbon monoxide. These Figures 12 and 15 show that, in accordance with the present invention, since a lean mixture is controlled which is laminated, the concentration of carbon monoxide is considerably reduced.

 In Figs. 13 and 16, the curved lines indicate the concentration (ppm) of hydrocarbons. These Figures 13 and 16 show that, in accordance with the present invention, since fuel is prevented from leaking into the exhaust pipe 22 and since a lean mixture is controlled which is stratified by control, the hydrocarbon concentration is greatly reduced.

 Figures 11 to 16 show results that have been obtained with fuel injection experiments in zone C of Figure 8 and, therefore, there is no possibility of carbon being discharged into the exhaust gas. . In addition, since a large amount of residual gas remains in the combustion chamber 6, the concentration of NOx is extremely low due to the presence of the residual gas, which performs the same function as recycled exhaust gas.

 The results of experiments highlighted in Figures 11 to 16 were obtained using gasoline. However, it has been confirmed that the specific fuel consumption, CO concentration and HC concentration, which are similar to those shown in Figures 11 to 16, can be obtained using other fuels, such as kerogen, light oil, propane and alcohol. In addition, it was also confirmed that stable combustion and uniform engine operation could be achieved regardless of octane number and cetane number. It is needless to say that the present invention can be applied to a four-stroke engine and rotary piston.

 Of course, the present invention is not limited to the embodiments described and shown; it is capable of many variants accessible to those skilled in the art, according to the envi saged applications and without one deviates from the spirit of the invention.

Claims (26)

 1.- Ignition-combustion method for an internal combustion engine comprising a combustion chamber, a fuel injector disposed in the combustion chamber, an air inlet for introducing fresh air into the combustion chamber. combustion and an exhaust gas outlet for discharging exhaust gases from the combustion chamber, characterized in that it consists of:  discharging the exhaust gases from the combustion chamber through said outlet orifice, while retaining a large amount of residual gas containing unburned components, incompletely burned components and oxygen, in the combustion chamber; combustion;  - uniformly supplying the combustion chamber with fresh air from said air intake opening while suppressing disturbances of the residual gas for the continuation of the oxidation reaction of the unburned components and incompletely burned components;  injecting fuel into the combustion chamber from the fuel injector to form a fuel mixture consisting of fuel and fresh air; and  compressing the residual gas and said fuel mixture in the combustion chamber in order to accelerate the oxidation reaction and to produce an auto-ignition of the residual gas, this self-ignited residual gas in turn producing an ignition of said combustible mixture.  2.- ignition-combustion method according to claim 1, charac terized in that the exhaust gas is discharged uniformly from the combustion chamber via the exhaust gas outlet orifice in order to remove the disturbance of the residual gas in the combustion chamber.  3. The ignition-combustion method according to claim 1, characterized in that said engine has an effective compression ratio which is less than 12: 1 and in that the fuel injector starts its injection operation before a crankshaft angle of about 500 upstream of the top dead center.  4.- All-combustion-combustion method for a 2-stroke engine comprising a combustion chamber, a fuel injector placed in this combustion chamber, a sweep orifice opening into the combustion chamber, an exhaust port discharging into the combustion chamber, a crankcase containing an inner chamber and a transfer passage for connecting the sweep orifice with the inner chamber of the crankcase, said method being  cherry in be eii, siste a ::  - supply fresh air to the inner chamber of the crankshaft,  compressing the fresh air in said crankcase chamber and discharging the exhaust gases from the combustion chamber through the exhaust port while retaining a large amount of residual gas containing unburned components, incompletely burned components and oxygen, in the combustion chamber;  - channel the fresh air in the crankcase chamber into the transfer passage;  limit the speed of fresh air flowing into the transfer passage when the engine is running under partial load;  - uniformly supplying the combustion chamber with fresh air from the purge orifice while suppressing disturbances of the residual gas for the continuation of the oxidation reaction of the unburnt components and incompletely burned components;  injecting fuel into the combustion chamber from the fuel injector to form a fuel mixture consisting of fuel and fresh air;  compressing the residual gas and the combustible mixture in the combustion chamber in order to accelerate the oxidation reaction and to produce an auto-ignition of the residual gas, this self-ignited residual gas in turn ensuring the ignition of said combustible mixture.  5.- ignition-combustion method according to claim 4, charac terized in that the flow of exhaust gas discharged from the combustion chamber via the exhaust port is strangled so as to suppress a disturbance of the residual gas in the combustion chamber.  6.- ignition-combustion process according to claim 4, charac terized in that the fresh air in the inner chamber of the crankcase is channeled into the transfer passage at the base of the inner chamber.  7.- ignition-combustion method according to claim 6, charac terized in that the fresh air flows into the transfer passage at a first distance at a first speed, and then flows into the transfer passage on a second distance, which is shorter than said first distance, and at a second speed which is lower than said first speed.  8. A method of ignition-combustion according to claim 4, charac terized in that said engine has an effective compression ratio which is less than 12: 1, and in that the fuel injector begins its injection operation before a crankshaft angle of about 50 upstream of the top dead center.  9. The ignition-combustion method according to claim 8, charac terized in that the injection operation is started by said fuel injector after opening the scanning orifice.  10.- 2-stroke internal combustion engine, characterized in that it comprises:  - a crankcase (10) comprising an inner chamber;  - a cylinder block (2) mounted on the crankcase and provided with a cylindrical bore (5);  - a piston (4) movable alternately in said cylinder bore (5), said piston and said cylinder bore defining a combustion chamber (6);  a fuel injector (12) disposed in the combustion chamber for injecting fuel into this chamber;  a transfer passage (27) having a sweeping orifice (26) at one end and an air inlet (16) at the other end, said sweeping orifice and said air intake opening opening respectively into said combustion chamber and into said crankcase chamber so as to transfer fresh air in said inner chamber to said combustion chamber;  - an exhaust passage (22) having an exhaust port (21) which opens into the combustion chamber (6) for discharging the exhaust gas from said combustion chamber; and  - Throttling means (28) disposed in said transfer passage (27) for limiting the rate of fresh air flowing into said transfer passage when the engine is operating under partial load.  11. A two-stroke internal combustion engine according to claim 10, characterized in that said engine further comprises another throttling means (23) for limiting the flow of exhaust gas discharged from the combustion chamber. (6) when the engine is running under partial load.  12. A two-stroke internal combustion engine according to claim 11, characterized in that said other throttling means comprises an exhaust control valve (23) disposed in said exhaust passage (22).  13. A two-stroke internal combustion engine according to claim 10, characterized in that said throttling means comprises a sweep control valve (28) placed in said transfer passage (27) so as to control the section said transfer passage.  14. A two-stroke internal combustion engine according to claim 13, characterized in that said sweep control valve (28) comprises an annular plate provided with an orifice which can be aligned with said transfer passage.  15.- 2-stroke internal combustion engine according to claim 14, characterized in that the passage section of the orifice of said annular plate is increased in connection with an increase in the level of the load of the engine.  16. A two-stroke internal combustion engine according to claim 10, characterized in that said transfer passage comprises a main passage (42) connecting the sweep orifice with the air intake orifice. and an auxiliary passage (51) derived from said main passage and connected to the inner chamber of said crankcase, said throttling means comprising a sweep control valve for selectively introducing fresh air into said combustion chamber from said air intake port or said auxiliary transport passage.  17.- 2-stroke internal combustion engine according to claim 16, characterized in that said auxiliary passage (51) has a length greater than that of the main passage (47) and has a cross section smaller than that of the main passage (47).  18.- 2-stroke internal combustion engine according to claim 17, characterized in that said auxiliary passage (51) is connected to the base of the inner chamber of said crankcase (1).  19. A two-stroke internal combustion engine according to claim 16, characterized in that said sweep control valve is arranged in the air inlet of said main passage.  20. A two-stroke internal combustion engine according to claim 19, characterized in that said sweep control valve (55) comprises an annular shaped member which is provided with an orifice which can be aligned with the orifice of air intake of the main passage.  21.- 2-stroke internal combustion engine according to claim 20, characterized in that the air inlet of the main passage is closed by said ring-shaped element when the engine operates under a partial load.  22. A two-stroke internal combustion engine according to claim 16, characterized in that said engine further comprises another transfer passage (47) which is closed by said sweep control valve (55) when the engine is running. under a partial load to stop the introduction of fresh air into said combustion chamber from said other transfer passage (47).  23.- 2-stroke internal combustion engine according to claim 16, characterized in that a stop valve is disposed in said auxiliary passage (51) so as to allow only a fresh air inlet into said chamber of combustion (6).  24. A two-stroke internal combustion engine according to claim 10, characterized in that said piston (4) has an approximately flat upper face.  25.- A two-stroke internal combustion engine according to claim 10, characterized in that said engine has an effective compression ratio which is less than 12: 1, and in that the fuel injector (12) begins its injection operation before a crankshaft angle of about 500 upstream of the top dead center.  26.- A two-stroke internal combustion engine according to claim 25, characterized in that the injection operation of said fuel injector (12) is started after opening said scanning orifice.