EP0296969A1 - Device for the induction under pressure of a mixture in the cylinder of an internal combustion engine - Google Patents

Abstract

The present invention relates to a method and a device for the induction under pressure of the fuel mixture into a first cylinder of an internal combustion engine, this engine comprising at least one other cylinder having a pump housing. <??>The device according to the invention is characterised in that it comprises a connecting pipe (15) between the housing (14) and the first cylinder (1) and in that there is an angular offset not equal to zero between the cycle of each of the cylinders. <IMAGE>

Description

The present invention relates to a method and devices for introducing pressurized fuel mixture at the end of air sweeping in a 2-stroke engine cylinder. The pressure source used is supplied by the pressure prevailing in the cylinder housing which is 120 ° behind the crankshaft (in the case of a 3, 6, ..., 3n cylinder engine) or by the cylinder housing which is delayed by 90 ° Crankshaft (in the case of a 4, 8, ..., 4n cylinder engine) with respect to the cylinder considered where the introduction of fuel mixture takes place. This pressure source is not stored.

The introduction of fuel mixture under pressure occurs on the arrival of this pressure source in the cylinder considered during its end of sweeping phase. The arrival of this pressure source in a fuel metering device prepares a fuel mixture which can be introduced into the cylinder through an orifice which will preferably be opened only during the arrival of this pressure source. This hole can be in the cylinder head.

In this case, the device may include a valve controlled to open during the arrival of this pressure source, or an automatic valve (type non-return valve), the opening of which is controlled by the pressure coming from the source of pressure. pressure.

The hole can also be in the cylinder. Its opening can then be controlled by the movement of the piston (in the case of a light) combined with a non-return device of the valve type (or with a rotary plug).

For example, one embodiment of this type can be to connect the cylinder housing delayed by 120 or 90 ° Crankshaft to the cylinder considered, via a transfer duct arriving opposite the exhaust side in the cylinder considered (duct generally called duct rear transfer).

Insofar as the place of metering of the fuel (upstream of the intake orifice opening into the cylinder) is not under a pressure greater than the ambient pressure during all the time outside the period of introduction of fuel mixture, this dosage can be done using low pressure injectors, but also using simpler devices, such as, for example, a carburetor of the type used for the intake of an engine two-stroke.

In general, the present invention relates to a device for introducing under pressure the fuel mixture into a first cylinder of an internal combustion engine, this engine comprising at least one other cylinder having a pump casing. The device according to the invention is characterized in that it comprises a connecting pipe between said pump casing and the first cylinder and in that there is a non-zero angular offset between the cycle of each of said cylinders.

This angular offset can be 120 ° and the cycle of the first cylinder can precede the cycle of the other cylinder by 120 °.

Likewise, this angular offset may be 90 ° and the cycle of the first cylinder may precede the cycle of the other cylinder by 90 °.

The device according to the invention applies in particular to engines comprising a number of cylinders multiple of 3 or 4.

The pipeline may open into the first cylinder in the vicinity of the cylinder head of the engine.

Likewise, the pipeline may open into the first cylinder on the side wall of this cylinder substantially at the bottom of this cylinder.

The device according to the invention may include a shutter member placed between the pipe and the first cylinder, substantially in the vicinity of the latter.

The shutter member may be a valve controlled by a cam, or electromagnetically, or a rotating plug.

Likewise, the shutter member may be automatic and be adapted to act like a valve.

The pipeline may include a fuel introduction and metering device.

This fuel introduction device may be a low pressure injector, just as it may include a venturi nozzle associated with said low pressure injector.

The fuel introduction device may be a carburetor.

The control of this carburetor can be coupled with a control that controls the amount of gas introduced into the pump housing of the first cylinder.

The device according to the invention may comprise between the carburetor and the pipe a non-return element such as a valve.

It will not depart from the scope of the present invention if the fuel introduction and metering member comprises a diaphragm pump actuated by the pressure pulses of a pump casing.

The outlet duct of this diaphragm pump which connects the latter to the pipeline, may include a system for adjusting its passage section. This system may include a needle and control means taking into account the average pressure of a casing.

The present invention also relates to a method of introducing the fuel mixture under pressure into a first cylinder of an internal combustion engine, this engine comprising at least one other cylinder having a pump casing. This method is characterized in that the pressure of the gases contained in said pump housing is used as a pressure source for injecting the fuel mixture into the other cylinder.

When the present invention relates to a multi-cylinder engine for which each cylinder comprises a pump casing, each of the cylinders may be connected to a pump casing of another cylinder angularly delayed.

Thus, in the case of a three-cylinder engine each having a pump casing, each cylinder may be in connection with the pump casing of the cylinder which is 120 ° behind the crankshaft.

According to the present invention, the connecting pipe does not serve as storage capacity and its volume can be relatively small.

• - la figure 1 illustre le principe d'utilisation de la pression régnant dans le carter du cylindre en retard de 120° Vilebrequin par rapport au cylindre considéré,
• - la figure 2 illustre le cas d'un retard de 90° Vilebrequin au lieu 120° Vilebrequin,
• - la figure 3 est relative au cas d'une introduction retardée de 120° Vilebrequin du mélange carburé dans la chambre de combustion du cylindre considéré, via une soupape commandée,
• - la figure 4 montre le cas d'une introduction retardée de 120° Vilebrequin du mélange carburé dans la chambre de combustion du cylindre considéré, via une soupape automatique,
• - la figure 5 illustre le cas d'une introduction retardée de 120° Vilebrequin du mélange carburé dans le transfert arriére du cylindre considéré, via un clapet anti-retour,
• - la figure 6 est relative au cas d'une introduction retardée de 120° Vilebrequin de mélange carburé dans le transfert arrière du cylindre considéré, via un boisseau rotatif,
• - la figure 7 montre le cas d'une introduction retardée de 90° Vilebrequin de mélange carburé dans le transfert arrière du cylindre considéré,
• - la figure 8 illustre un dispositif de dosage et d'introduction du carburant par la pression régnant dans le carter,
• - la figure 9 est semblable à la figure 8, mais avec le perfectionnement du dispositif de dosage en fonction de la charge moteur, et
• - la figure 10 montre le cas d'une introduction de mélange carburé préalablement admis via un carburateur classique.

The invention will be clearly understood on reading the following description of exemplary embodiments illustrated by the appended figures, among which:

• FIG. 1 illustrates the principle of using the pressure prevailing in the cylinder crankcase which is 120 ° crankshaft late with respect to the cylinder considered,
• FIG. 2 illustrates the case of a 90 ° crankshaft delay instead of 120 ° crankshaft,
• FIG. 3 relates to the case of a delayed introduction of 120 ° crankshaft of the fuel mixture into the combustion chamber of the cylinder in question, via a controlled valve,
• FIG. 4 shows the case of a delayed introduction of 120 ° crankshaft of the fuel mixture into the combustion chamber of the cylinder in question, via an automatic valve,
• FIG. 5 illustrates the case of a delayed introduction of 120 ° crankshaft of the fuel mixture into the rear transfer of the cylinder in question, via a non-return valve,
• FIG. 6 relates to the case of a delayed introduction of 120 ° crankshaft of fuel mixture into the rear transfer of the cylinder in question, via a rotary plug,
• FIG. 7 shows the case of a delayed introduction of 90 ° crankshaft of fuel mixture into the rear transfer of the cylinder considered,
• FIG. 8 illustrates a device for metering and introducing fuel by the pressure prevailing in the crankcase,
• FIG. 9 is similar to FIG. 8, but with the improvement of the metering device as a function of the engine load, and
• - Figure 10 shows the case of an introduction of fuel mixture previously admitted via a conventional carburetor.

Figure 1 shows in solid lines with the reference P1, the pressure variation curve in the cylinder during the scanning of this cylinder or cylinder considered.

The curve of variation of the pressure of the casing equipping this cylinder is indicated in dotted lines, and bears the reference P3, and the variation of the pressure in the casing of the cylinder lagging by 120 ° is indicated in dashed lines and bears the reference P2. This housing delayed by 120 ° relative to the cylinder considered represents the pressure source. Figure 1 shows that the pressure of this source is higher than the cylinder pressure during a large part of the scanning, corresponds to the hatched part in this figure.

This pressure source can therefore allow the introduction of fuel mixture during this whole part of the operating cycle of the cylinder considered where the pressure difference is sufficient. By the choice and the design of the method of introduction adopted, controlled valve, automatic valve, light more valve, or light more rotary valve, it is possible to control more or less the most favorable moment for the introduction of this fuel mixture.

FIG. 2 shows the same case, this time with a pressure source coming from a crankcase 90 ° behind the crankshaft relative to the cylinder considered, this corresponds in particular to the case of an engine comprising four cylinders. The principle is the same, with however a source of pressure available with an offset of 90 ° Crankshaft arriving 30 ° Crankshaft earlier in the sweep.

The two figures also show that during a whole other large part of the cycle, the pressure in the cylinder considered (which is moreover not represented over the entire cycle since its values would go out of the scale of the figures), is greater than the pressure of the pressure source, however, it is important that there is no exchange in the cylinder direction considered towards pressure source, so as not to disturb the operation of the pressure source and the associated fuel metering device.

Figures 3, 4, 5, 6, 7 show in solid lines the cylinder considered 1 with its piston 2 at the end of scanning, its exhaust 3, its exhaust light 4 which is about to be closed, its lights lateral transfer 5, and rear transfer 6, its casing 7 with an air intake only, for example by valves 8, its spark plug 9, the rod-crank system 10.

In dashed lines is shown the cylinder 11 having a piston 12 whose movement is angularly delayed by 120 ° by means of the rod-crank system 13, relative to the piston 2 of the cylinder considered 1. The piston 12 is in the expansion phase in the cylinder 11 and at the same time of compression in the pump casing 14.

The pump housing 14 whose movement of the piston 12 is angularly delayed by 120 ° supplies the pressure source through the conduit 15.

In the case of FIGS. 3 and 4, this duct is connected to the combustion chamber 16 of the cylinder considered 1. The rear transfer 6 of the cylinder 1 can then optionally be connected to its own pump housing 7 by the duct 17.

The introduction of the pressurized air from the pump housing 14 into the chamber 16 takes place through an orifice 18, the opening of which is controlled by a valve 19. Upstream of the valve is a device for introducing and low-pressure fuel metering 20.

This device can be a low-pressure injector that is found commercially, or a fuel pump actuated by successive pressures and depressions of a pump housing. A diagram of this latter device will be specified in FIG. 8. The introduction of the liquid fuel can take place in the duct 15 both during the whole time when the valve 19 is closed and during the time when it is open.

This fuel metering and introduction device 20 can be associated with a venturi nozzle 21 placed in the duct 15, just upstream from the valve 19 and the orifice 18, in accordance with patent EP-189,714, in order to improve the spraying of fuel with air from the pressure source (pump housing 14).

Just downstream of the orifice 18, it is also advantageously possible to place a deflector 22, or device for orienting the jet of mixture introduced into the cylinder. This device forming part of the cylinder head or attached to the cylinder head is of the type, for example, described in patent EP-189,715.

In the particular case of FIG. 3, the valve 19 is controlled mechanically, for example by a cam 23 driven in rotation at the speed of the motor. This cam controls the movement of the valve 19 by means of a pusher 24. The valve 19 is returned by a spring 25.

In the particular case of FIG. 4 which illustrates another variant, the valve 19 is not controlled. It is simply fitted with a return spring 25. It is left free to move as a function of the upstream and downstream pressure differences. It then acts like a flap or automatic valve.

The control of the valve can be done by an electromagnetic system which can be controlled electronically.

In the case of the two figures 3 and 4, when the pressure in the casing 14 is greater than the pressure in the cylinder 1 considered (FIG. 1), the introduction of fuel mixture can occur in the cylinder 1, either at the selected ordered moment (Fig. 3), or automatically during this period of pressure difference, between casing 14 and cylinder 1 (Fig. 4). In both cases, the movement of the piston 2 is such that it closes the exhaust port 4 before the fuel can escape from the cylinder 1 in the exhaust 3, through this same port 4.

In the case of FIGS. 5 and 6, the duct 15 coming from the source of compressed air 14 is connected to a transfer light, preferably to the rear transfer light 6, so called because it is substantially opposite to the light of exhaust. Near the light 6 and downstream from it, a non-return valve 26 prevents the gases from the cylinder 1 from penetrating into the casing 14 during the depression phase of the latter.

Upstream of the valve, there is the device 27 for metering and introducing low-pressure fuel. This fuel introduction can take place at any time during the cycle, even when the light 6 is closed by the piston 2.

This fuel metering and introduction device 27 can be a low-pressure injector that is commercially available, or a fuel pump actuated by the successive pressures and depressions of a pump housing (Fig. 8) , or a conventional carburetor activated by the air flow passing through it. In the latter case, a second external air intake circuit should be provided, for example through this carburetor and through the duct 15. A schematic representation is made of it in FIG. 10.

In all cases, the spraying of the fuel mixture may be advantageously improved by a nozzle-venturi type device 28 placed just upstream of the valve 26 in accordance with patent FR-2,575,521.

In the case of Figure 6, the valve 6 is replaced by a plug rotary 29 driven by the rotation of the motor and thus preferably controlling the opening of the light 6.

Figure 7 shows the case of Figure 6 where the pressure source is provided by the movement in the pump housing 14 of a piston 12 angularly delayed by 90 ° Crankshaft relative to the movement of the piston 2 of the cylinder considered 1. It It is obvious that the cases of FIGS. 3, 4, 5 could also be described in the same way with this delay of 90 ° V instead of 120 ° V.

FIG. 8 shows a schematic representation of a fuel metering device which can be used in place of the devices 20 or 27.

This device pumps the fuel from the tank 30 via the non-return valve 31 to the duct 34 through the non-return valve 33. The membrane 32 acts as a fuel pump. On the one hand it is in contact with the fuel it pumps. On the other side, its reciprocating movement which allows this pump role is actuated by the pressure pulses coming from a pump casing which can be either casing 7 or casing 14 and which is connected to this side of the membrane via conduit 35.

During the intake phase of the pump crankcase, the latter is under vacuum and therefore controls the diaphragm 32 so as to increase the volume 36 thereby sucking fuel through the valve 31 which opens. Then, during the compression phase of the casing, the movement of the diaphragm 32 reduces the volume 36 and therefore pumps the fuel into the duct 34 via the valve 33.

This device therefore acts as a pump and fuel metering. It is slaved to the engine speed, since it provides one pump movement per revolution, and it is also slaved to the load since the amplitude of the pressure pulses in the crankcase is proportional to the load.

In the case where it is used alone, without additional finer metering means, the pipe 34 is then directly connected to the location in the pipe 15 where the fuel is introduced.

In the case where a finer adjustment of the fuel flow rate relative to the load is necessary, the opening of the duct 34 is adjusted as a function of the load by a needle 37 which can be actuated either directly or indirectly by a lever 38 connected to another membrane 39. The other side of the membrane 39 is again in communication with the pressure of a motor crankcase via a conduit 40.

The inertia of the assembly constituted by the needle 37, the lever 38 and the membrane 39 is chosen such that it does not allow movement of the membrane 39 according to the pulsations of instantaneous pressure of a casing. It must be studied in order to be controlled only by the average pressure of a crankcase, a pressure which is directly representative of the engine load. This results in a position of the metering needle directly representative of the engine load. At the point of the needle, the fuel thus dosed is guided by the pipe 41 to the place of introduction into the pipe 15.

Finally, Figure 10 shows another particularly simple embodiment of the metering device.

The pressure source of the casing 14 through the conduit 15 which serves for the introduction of fuel mixture into the cylinder 1, also serves during its vacuum phase for the suction of very rich fuel mixture via a conventional carburetor 42 and a device non-return valve 43. The carburetor is for example a carburetor of the conventional type for 2-stroke engine, with plug and needle correcting the nozzle nozzle with the load.

The assembly then forms a true second very rich mixture intake circuit, separated from the intake via the air valve 8 only.

The length of the conduit 15 may be studied so as not to allow the fuel mixture thus admitted into this conduit, to reach the pump housing 14, before being pushed back into the cylinder 1 by the pressure of the pump housing 14 returned to phase compression.

Another very advantageous advantage lies in the fact that, in the case of a multi-cylinder engine whose set of cylinders operates according to the principle of the invention, with the suitable combinations of conduits 15, a single carburetor 42 can be used for all of the cylinders. Downstream of the carburetor, the different conduits 44 can be separated to end up at the different cylinders, in order to be able to supply with fuel mixture their respective conduits 15 through their respective valves 43.

The carburetor device of FIG. 10, a variant of the case of FIG. 5, can also be adapted to the case of FIGS. 3, 4 and 6.

According to the present invention the conduit 15 which connects the pump housing 14 to the combustion chamber of a cylinder 1 does not constitute a storage capacity, but essentially serves to convey the compressed gas in the pump housing 14 to the cylinder 1 Thus it is important according to the present invention that the duct 15 has a passage section sufficient not to create too great pressure losses of the transferred gas, but a small volume so as not to limit the compression ratio of the pump casing.

It should be noted that according to the present invention there is no need for the duct 15 to be connected directly to an exhaust pipe. According to the present invention, it is possible not to use the pressure of the exhaust gases to carry out the injection of the combustible.

It will not depart from the scope of the present invention if the control of the valve 19 is pneumatic or hydraulic.

Claims (20)

1. - Device for introducing the fuel mixture under pressure into a first cylinder of an internal combustion engine, this engine comprising at least one other cylinder having a pump casing, characterized in that it comprises a connecting pipe ( 15) between said pump housing (14) and the first cylinder (1) and in that there is a non-zero angular offset between the cycles of said cylinders. 2. - Device according to claim 1, characterized in that said angular offset is 120 ° and in that the cycle of the first cylinder precedes by 120 ° the cycle of the other cylinder. 3. - Device according to claim 1, characterized in that said angular offset is 90 ° and in that the cycle of the first cylinder precedes by 90 ° the cycle of the other cylinder. 4. - Device according to claim 2, characterized in that said engine comprises a number of cylinders multiple of 3. 5. - Device according to claim 4, characterized in that said engine comprises a number of cylinders multiple of 4. 6. - Device according to claim 1, characterized in that said pipe (15) opens into the first cylinder in the vicinity of the cylinder head of the engine. 7. - Device according to claim 1, characterized in that said pipe (15) opens into the first cylinder (1) on the side wall of this cylinder, substantially at the bottom of this cylinder. 8. - Device according to claim 1, characterized in that it comprises a shutter member (19, 26, 29) placed between said pipe (15) and said first cylinder (1), substantially in the vicinity of the latter. 9. - Device according to claim 8, characterized in that said shutter member is a valve (19) controlled by a cam (23) or electromagnetic. 10. - Device according to claim 8, characterized in that said shutter member is automatic and is adapted to act in the manner of a valve. 11. - Device according to claim 8, characterized in that said shutter member is a rotating plug (29). 12. - Device according to claim 1, characterized in that said pipe comprises a fuel introduction and metering member (20, 27, 42). 13. - Device according to claim 12, characterized in that said fuel introduction device is a low pressure injector. 14. - Device according to claim 13, characterized in that it comprises a venturi nozzle (21, 28) associated with said low pressure injector. 15. - Device according to claim 12, characterized in that said fuel introduction device is a carburetor (42). 16. - Device according to claim 15, characterized in that the control of said carburetor is coupled with a control which controls the amount of gas introduced into the pump housing of said first cylinder. 17. - Device according to claim 15, characterized in that it comprises between the carburetor (42) and said pipe a non-return element, such as a valve (26). 18. - Device according to claim 12, characterized in that said fuel introduction and metering member comprises a diaphragm pump (32) actuated by the pressure pulses of a pump housing. 19. - Device according to claim 18, characterized in that the outlet conduit (34) of said diaphragm pump which connects the latter to said pipe (15), comprises a system for adjusting its passage section, this system comprising a needle (37) and control means taking into account the average pressure of a casing. 20. - Method of introducing under pressure the fuel mixture into a first cylinder of an internal combustion engine, this engine comprising at least one other cylinder having a pump housing, characterized in that the gas pressure is used contained in said pump housing as a pressure source for injecting the fuel mixture into the other cylinder.

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