EP0189716A2 - Apparatus for the injection of fuel into an internal-combustion engine assisted by compressed air or gas - Google Patents

Abstract

The present invention relates to a device and a method for pneumatically injecting fuel into an engine. The device is characterized in that it comprises at least one auxiliary pipe (20) having two ends, one of which is connected to an exhaust pipe (16) and 1 other to an injection member (12).

Description

The present invention relates to a device and method allowing and / or improving fuel injection assisted by air or compressed gases, or pneumatic injection on an internal combustion engine comprising at least one pump housing. The present invention is, in particular, applicable to a two-stroke engine with air sweeping.

In the particular case of the two-stroke engine scanned by the crankcase during a significant part of the air and fuel intake cycle, the transfer and exhaust ports are open simultaneously and part of the admitted air-fuel mixture s 'escapes into the atmosphere before closing the exhaust ports Hence a significant reduction in efficiency and high emissions of pollutants.

The injection of fuel by assisted air from the crankcase overcomes this drawback. An example has been proposed by M. J.A. CULMANN in French patent FR-490.166. According to this patent, the cylinder is scanned with only air coming from the pump casing, another part of the air from the pump casing is introduced, under a pressure close to the maximum pressure reached in this casing, in a sealed chamber which serves as a source of compressed air to supply the pneumatic fuel injection device.

It has been found that such a device works better when it is supplied with compressed air at a higher pressure than that prevailing in the pump housing.

The prior art can be illustrated by British patents GB-A-572,080, German DE-C-833,885, American US-A-3,190,271 and French FR-A-2,292,111.

The device according to the invention uses the pressure wave effects prevailing in the exhaust pipes to increase the pressure of this sealed chamber by introducing air and / or exhaust gases into it. This results in a better quality of the pneumatic injection, an increase in the air filling of the engine, an increase in the quantity of residual gases burned, hence a reduction in nitrogen oxide emissions, a partial recovery of the short fuel. -exhaust circuitry and possible reduction of noise due to the effects of exhaust pressure waves.

Thus, the present invention relates to an internal combustion engine comprising a pneumatic fuel injection member, an exhaust pipe and a pump casing.

It is characterized in that the engine comprises a chamber connecting the pump casing to the injection member, this chamber constituting an injection chamber, an auxiliary pipe connecting the exhaust pipe to said injection chamber, and in that this injection chamber comprises an obstruction member, such as a non-return valve or valve, this member being located before the connection of the auxiliary pipe to the injection chamber.

The auxiliary pipe may include an obstruction member such as a non-return valve or valve, this member opening intermittently due to a mechanical control such as a cam, pneumatic, electropneumatic, etc.

It will not depart from the scope of the present invention if the auxiliary pipe has a third opening leading to a gas source and an obstruction member placed on said opening such as a non-return valve or valve.

The end of the auxiliary pipe connected to the exhaust pipe may preferably be positioned on this pipe at a place where the pressure wave is maximum.

The end of the auxiliary pipe connected to the exhaust pipe may have the shape of a convergent whose section decreases going from the exhaust manifold to the auxiliary pipe.

The present invention can be applied to an engine comprising at least two cylinders, each of which comprises an exhaust pipe, an injection member and an injection chamber connected to the injection member of one of the cylinders, or cylinder considered. In this case, the engine may also include at least one cross auxiliary pipe, connecting said injection chamber to the exhaust pipe of the other cylinder.

If it is the cylinder in question which comprises a pump casing, the engine may comprise at least one injection chamber connecting said pump casing to the injection member of the cylinder in question and the crossed auxiliary pipe may connect the exhaust manifold from the other cylinder to the injection chamber of the cylinder in question.

The present invention can be applied to an engine comprising at least two cylinders, each of these cylinders having an exhaust manifold and an injection member. In this case, the engine may also comprise at least two crossed auxiliary pipes, each of them connecting the exhaust pipe of one of the cylinders to the injection member of the other cylinder.

If 03 engine is an engine whose cylinders include a pump casing, it may also include at least two injection chambers, each of them connecting the pump casing of one of the cylinders, or cylinder considered, to the member d injection of the same cylinder and each of the auxiliary pipes can connect the exhaust pipe of the other cylinder to the injection chamber connected to the injection member of the cylinder in question.

The present invention can be applied to an engine comprising at least two cylinders, at least one of which comprises a pump housing. In this case, the engine may include at least one so-called crossed injection chamber connecting said pump casing to the injection member of the other cylinder. It will not depart from the scope of the present invention if this other cylinder has an exhaust pipe and an auxiliary pipe connects the exhaust pipe of this other cylinder to the cross-injection chamber connected to the injection of this same cylinder.

The present invention can be applied to an engine having at least two cylinders each equipped with a pump housing. In this case, the engine may comprise at least two crossed injection chambers, each of them connecting the pump housing of one of the cylinders to the injection member of the other cylinder.

It will not depart from the scope of the present invention if the engine comprises at least two auxiliary pipes, each of them connecting the exhaust pipe of one of the cylinders, or cylinder considered, to the injection chamber connected to the injection member of the same cylinder.

Thus, it appears that, in the case of mutticytindres, the present invention allows numerous combinations of communications between the exhaust pipes of the different cylinders and the injection members, as well as between the pump casings and the injection members .

Similar combinations are also possible in the context of the present invention, in particular, when the engine comprises an exhaust manifold or if it comprises a common injection chamber communicating with several pump casings and at least one injection member. For example, it will not depart from the scope of the present invention if an auxiliary pipe is connected to an injection member via, or not, the common injection chamber.

The injection chamber may consist of a pipe, this is also a preferred embodiment.

The present invention also relates to a method for injecting fuel into an internal combustion engine equipped with a pneumatic injection member and an exhaust pipe and comprising a pump casing. This process is characterized in that communication is established between the exhaust pipe and the injection member, in that a part of the compressed gases coming from the pump casing is directed towards the injection member and combines with the gases from the communication between the exhaust and the injection member.

It will not depart from the scope of the present invention if the communication is brought into contact with a gas source via an obstruction member such as a non-return valve.

When the engine to which the method according to the invention is applied, comprises at least two cylinders, each of which comprises an exhaust pipe and an injection member, it is possible to establish at least one so-called cross communication connecting the exhaust pipe of the 'one of the cylinders or cylinder considered in the injection member of the other cylinder.

If the method according to the invention is applied to an engine for which each of said cylinders comprises a pump casing and a transfer duct, a portion of the compressed gases coming from the pump casing of said cylinder considered may be directed to the injection member of this same cylinder and combine with the gases coming from the communication between the exhaust pipe of the other cylinder to the injection member of the cylinder in question.

If the method according to the invention is applied to an engine comprising at least two cylinders, at least one of these cylinders comprising a pump casing, a portion of the compressed gases originating from the pump casings may be directed to the injection member from another cylinder.

When the method according to the invention is applied to an engine in which each cylinder has an exhaust manifold, the communication can connect the exhaust manifold of this other cylinder to the injection member of this same cylinder and at least part of the compressed gases coming from said pump casing can be directed towards the injection member and combines with the gases coming from the communication.

• - la figure 1 montre schématiquement et en coupe un moteur deux temps à balayage par le carter, avec injection de carburant assistée par air ou gaz comprimé provenant d'un tube ou d'une chambre étanche alimenté en air par le carter et équipé du dispositif suivant l'invention,
• - les figures 2 à 6 illustrent le fonctionnement de ce moteur,
• - les figures 7, 8 et 9 représentent des variantes de réalisation, et
• - les figures 10, 11, 12 et 13 représentent des exemples d'applications particoliers dans le cas de moteurs mutticytindres.

The advantages and characteristics of the invention will be highlighted in the following description, given by way of nonlimiting example, with reference to the appended figures among which:

• - Figure 1 shows schematically and in section a two-stroke engine scanned by the housing, with fuel injection assisted by air or compressed gas from a tube or a sealed chamber supplied with air by the housing and equipped with the device according to the invention,
• - Figures 2 to 6 illustrate the operation of this engine,
• FIGS. 7, 8 and 9 represent alternative embodiments, and
• - Figures 10, 11, 12 and 13 show examples of special applications in the case of multi-cylinder engines.

Figure 1 is a schematic representation of a cylinder of a two-stroke engine with fuel injection assisted by compressed air and equipped with a device according to the invention.

The reference ₁ designates the cylinder closed at its upper part by the cylinder head 2 and which communicates at its lower part with a sealed casing 3.

In the cylinder moves the piston 4 connected by the connecting rod 5 to the crankshaft 6.

Lights 7 made in the wall of cylinder 1 communicate with the exhaust manifold - shown diagrammatically at 8.

Lights 9 made in the wall of the cylinder 1 allow the introduction of air into the cylinder. These lights 9 communicate with the sealed casing 3 through the transfer channel 10.

Lights 7 and 9 have the arrangement and dimensions known in the art to ensure efficient filling of the cylinder and as complete evacuation of the burnt gases.

The casing 3 is provided with an air intake orifice 11 equipped with a valve shown diagrammatically in 11a and which is, for example, a blade valve. The orifice 11 is connected to an air filter, not shown. The valve 11a is open and allows air to enter the casing 3 when the pressure in the casing is less than the pressure of the supply air. The valve 11 closes as soon as the pressure in the casing 3 is greater than the pressure of the supply air.

The casing 3 communicates with a sealed chamber ₁ 7 of volume V through an orifice 18 fitted with a valve 19 such as a blade valve.

The valve 19 opens to put the chamber 17 in communication with the rest of the casing when the pressure in the chamber 17 is lower than the pressure prevailing in the rest of the casing. The valve closes, isolating the chamber 17 from the rest of the housing, when the pressure in the chamber ₁ 7 is greater than the pressure prevailing in the rest of the housing.

A pneumatic fuel injection member - shown diagrammatically at 12, makes it possible to introduce into the cylinder 1 a mixture of carburetted air under pressure. To this end, the member 12 is connected to a fuel supply pipe 13 and to a compressed air and / or compressed gas supply pipe 14 which communicates with the chamber 17. This member and its control means will be described in detail below.

The cylinder head 2 also carries a spark plug 15 whose electrical supply circuit has not been shown.

The device according to the invention comprises an auxiliary tube or pipe 20 connecting the exhaust pipe 16 with the sealed chamber 17, the communication between the tube 20 and the sealed chamber 17 being made through an orifice 21 fitted with a valve 22 such than a reed valve.

The valve 22 opens to put the tube 20 in communication with the sealed chamber 17 when the pressure in the tube is greater than the pressure prevailing in the sealed chamber. The valve 22 closes, isolating the chamber 17 from the tube 20, when the pressure in the chamber is greater than that prevailing in the tube 20.

The operation of the engine is described below with reference to Figures 2 to 6.

In FIG. 2, the piston 4 has reached top dead center by moving towards the cylinder head 2. The intake 9 and exhaust 7 ports are closed by the piston 4, the valve 11 a is open letting the air in the housing through the orifice 11. The valve 19 is closed. The valve 22 is closed.

Under the action of combustion triggered by the spark plug 15, the piston 4 moves away from there cylinder head 2 by compressing the air contained in the casing 3 which causes the valve 11 to close When the pressure is higher to that prevailing in the chamber 17, the valve 19 opens (Fig. 3). The pressure in the entire casing continues to rise as the piston 4 moves.

When the sudden opening of the exhaust ports 7 occurs (Fig. 4) an incident wave of high pressure (exhaust puff) is formed and propagates in the exhaust pipe 16 and in the tube 20. When this positive pressure wave reaches the orifice 21, the pressure being higher in the tube 20 than in the chamber ₁ 7, the valve 22 opens and part of the gas contained in the tube 20 (exhaust gases consisting of a mixture of burnt gases, air and possibly fuel from the short-circuiting) is introduced into the chamber 17, the pressure of which is thus increased.

When the piston discovers the transfer ports 9 (Fig. 5) the pressurized air contained in the casing 3 is introduced into the cylinder 1 via the transfer channel 10 and the ports 9. The pressure in the casing decreases and the valve ₁ 9 closes. The pressure of the air stored in the chamber 17 would then be equal to the maximum pressure reached in the whole of the casing 3, if the engine were not equipped with the device according to the invention.

The length of tube 20 can be calculated in such a way that the positive exhaust pressure wave arrives at the orifice 21 to fill the chamber 17 after the opening of the transfer lights 9, that is to say when the casing 3 has finished supplying the chamber 17 so as not to disturb or reduce this supply, this is particularly true when there is a delay between the opening of the transfer light relative to the opening of the exhaust lights. The shape of the tube 20 is studied to promote the wave effect. This can be a tube whose curvature is regular and may also include sudden or gradual changes in section, for example in the form of diverging or converging cones.

Thus, when the member 12 is actuated, it is supplied with air and exhaust gas through the pipe 14 at a maximum pressure. The instant of introduction of the fuel mixture under pressure is determined by the adjustment of the control means of the member 12 so that there is practically no loss of fuel mixture by the exhaust ports, the pressure of supply to the injector at this time being greater than that prevailing in the cylinder.

Then the piston 4 moves towards the cylinder head 2 creating a compression of the fuel mixture in the cylinder 1 and a depression in the casing 3. The valve 19 remains closed while the valve 11 a opens allowing air to penetrate into the housing 3 (Fig. 6).

The operating steps described above are then reproduced in the same order.

It would not be departing from the scope of the invention to arrange the fuel spraying member 12 located in the cylinder head 2 of the engine in the transfer channel 10 so that it carries out the introduction of the fuel mixture through the orifices of intake as shown schematically in Figure 7, as well as at any other location on the useful volume of the cylinder.

Of course, the exact location of the member 12 on the cylinder head 2 or the transfer channel 10, or the cylinder, will be determined by the technician so that the quantity of fuel mixture escaping through the ports 7 before you burn it is zero or as low as possible.

It will not depart from the scope of the present invention to apply the invention to a four-stroke engine or to a two-stroke engine having pump casings and comprising valves.

A variant of the device consists in adding to the complete engine previously described on the tube 20 a short tube 23 opening into the open air or into an air filter through the orifice 24 or into a gas source such as, for example, a source fuel mixture. The orifice is equipped with a valve 25 which can for example be a blade valve (FIG. 8).

When the positive exhaust pressure wave has reached the orifice 21 and participated in the filling of the chamber 17, that is to say when the valve 22 is closed, it can be followed by means of a configuration of the exhaust manifold. adapted, by a negative pressure wave which after passage through the tube 23 reaches the orifice 24 and causes the valve 25 to open, the pressure in the tube 23 then being less than the atmospheric pressure of the outside air. Air is therefore introduced and sucked into the tubes 20 and 23.

It is this air instead of the exhaust gases which then goes to the next engine cycle to be introduced through the orifice 21 into the chamber 17 in accordance with the mechanism described above using the positive exhaust pressure wave coming from the abrupt opening of the exhaust lights 7.

The location 26 (whether in the case of FIG. 1 as well as in that of FIG. 8) of the connection of the tube 20 on the exhaust manifold 16 is judiciously chosen to obtain a sufficient wave effect

It may be envisaged in the case of an insufficient wave effect to open the valve 22 and therefore to reach in the tube 20 a pressure higher than that of the sealed chamber 17, to use any exhaust configuration or any device allowing to artificially increase the pressure wave effects.

An example of such a device can be a butterfly 27 placed just after connection 26 in the pipe 16 - (Fig. 9) whose opening angle can be corrected according to the operating characteristics of the engine.

Another example concerning the configuration of the pipe would be to give a form of convergent 26a (FIG. 9) to the pipe 20 at the connection 26 to the exhaust manifold, this convergent having a section which decreases going from the manifold d exhaust 16 to line 20.

In the case of a two-stroke multi-cylinder engine, different combinations could be envisaged: a sealed chamber per cylinder, this is the case in FIGS. 10, 11 and 12, or on the contrary common to different cylinders. In the first case, these sealed chambers 17, 17a, 17b and / or 17c may be supplied by the casing 3, 3a, 3b and / or 3c of the cylinder in which they inject the air, in the case of FIGS. 12 and possibly 1 or on the contrary by the casing of one of the other cylinders, in the case of FIGS. 10 and 11. Similarly, each tube 20 according to the invention corresponding to injection into a cylinder could in fact be connected - (communication 26) to the exhaust pipe 16 of the same cylinder, case of FIGS. 10, 11 and possibly 1, as well as that of a different cylinder, case of FIG. 12.

An example of a particular application could be, in the case of a multi-cylinder, to have the sealed chamber inflated by the casing of another cylinder and the exhaust communicating with the sealed chamber used for injection into its own cylinder. In this case, a very short tube 20 may be sufficient since it is no longer essential for the positive wave to arrive after the opening of the transfer lights. One can also in this case use the geometry of the tube 20 to increase the pressure wave effects (for example by a short and convergent tube 20).

Figures 10 and 11 therefore show such applications to 2 and 3 cylinder engines. The principle can be generalized to engines with a higher number of cylinders.

Conversely, another possibility (FIG. 12) is that each cylinder has its individual sealed chamber supplied by its own casing and by a tube 20 coming from the exhaust of one of the other cylinders.

Finally, another possibility is to use a sealed chamber common to all the cylinders or only to a few cylinders and supplied by each engine casing and by tubes 20 coming from each exhaust, this sealed chamber being connected to at least certain organs of injection of the engine.

FIG. 13 represents the case of a chamber 17 ′ connected to two different pump casings 3 and 3a. This chamber is extended by a pipe 17a 'up to a spraying member 12. Furthermore, this pipe is connected to an exhaust pipe 17a' by an auxiliary pipe 20.

Of course, the chamber 17 ′ can be connected to one or more spraying members.

Claims (21)

1. - Internal combustion engine comprising at least one pneumatic fuel injection member (12) at least one exhaust manifold (16) and a pump housing (3), characterized in that it comprises a chamber (17 ) connecting said casing to said injection member (12), said chamber constituting an injection chamber, an auxiliary pipe (20) connecting said exhaust pipe (16) to said injection chamber (17) and in that said injection chamber comprises an obstruction member (18), such as a non-return valve or valve, this member being located before the connection of said auxiliary pipe to said injection chamber. 2. - Motor according to claim 1, characterized in that said auxiliary pipe (20) comprises an obstruction member (22) such as a non-return valve or valve. 3. - Motor according to claim 1, characterized in that said auxiliary pipe (20) has a third opening (23) opening onto an air source and an obstruction member (25) placed on said opening such as a valve or a non-return valve. 4. - Engine according to claim 1, characterized in that the end (26) of the auxiliary pipe (20) connected to the exhaust pipe (16) is positioned on this pipe at a place where the pressure wave is maximum. 5. - Engine according to claim 1, characterized in that the end (26) of the auxiliary pipe (20) connected to the exhaust pipe (16) has the shape of a convergent whose section decreases from the exhaust manifold (16) to the auxiliary pipe (20). 6. - Engine according to claim 1 comprising at least two cylinders each of which comprises an exhaust pipe and an injection member and an injection chamber connected to the injection member of one of the cylinders, or cylinder injection, characterized in that it comprises at least one cross auxiliary duct connecting said chamber to the exhaust pipe of the other cylinder. 7. - Engine according to claim 6, for which said cylinder comprises a pump housing (3), characterized in that it comprises at least one injection chamber (17, Fig. 12) connecting said pump housing (3) to the injection member (12) of said cylinder in question and in that the cross auxiliary pipe (20a) connects the exhaust pipe of the other cylinder to the injection chamber of the cylinder in question. 8. - An engine according to claim 1 comprising at least two cylinders each of which comprises an exhaust pipe and an injection member, characterized in that it comprises at least two crossed auxiliary pipes, each of them connecting the pipe d exhaust from one of the cylinders to the injection member of the other cylinder. 9. - Engine according to claim 6, each of said cylinders comprising a pump housing, characterized in that it comprises at least two injection chambers (17, 17a, Fig. 12), each of them connecting the pump housing ( 3, 3a) of one of the cylinders, or cylinder considered, to the injection member - ( ₁ 2, ₁ 2a) of this same cylinder and in that each of the auxiliary pipes (20, 20a) connects the tubing exhaust from the other cylinder to the injection chamber connected to the injection member of the cylinder in question. 10. - Engine according to claim 1 comprising at least two cylinders, at least one of these cylinders comprises a pump casing, characterized in that it comprises at least one so-called injection chamber characterized in that it comprises at minus a so-called cross injection chamber (17, Fig. 10) connecting said pump casing to the injection member of the other cylinder (12a). 11. - Engine according to claim 10, wherein said other cylinder comprises an exhaust pipe, characterized in that it comprises at least one auxiliary pipe connecting the exhaust pipe of said other cylinder to the cross injection chamber at the injection member of this same cylinder. 12. - Engine according to claim 1 comprising at least two cylinders, each of these cylinders each having a pump housing, characterized in that it comprises at least two crossed injection chambers (17, 17a, Fig. 10), each of them connecting the pump housing of one of the cylinders to the injection member of the other cylinder (12, 12a). ₁ 3. - Motor according to claim ₁ 2, wherein each cylinder comprises an exhaust pipe, characterized in that it comprises at least two auxiliary pipes, each of them connecting the exhaust pipe of one of the cylinders, or cylinder considered, to the injection chamber connected to the injection member of this same cylinder. 14. - Engine according to claim 1 comprising at least two cylinders each having a pump housing, characterized in that it comprises a common injection chamber connected to said pump housings via obstructions such as a valve or check valves. back, said injection chamber being moreover connected to at least one injection member, and in that at least one auxiliary pipe is connected to said injection chamber. 15. - Engine according to one of claims 1 to 14, characterized in that said injection chamber is constituted by a pipe. 16. - Method for injecting fuel into an internal combustion engine equipped with a pneumatic injection member and an exhaust pipe and comprising a pump casing, characterized in that communication is established between the exhaust pipe and the injection member in that part of the compressed gases coming from the pump casing is directed towards the injection member and combines with the gases coming from said communication between the exhaust and the injection organ. 17. - Method according to claim 16, characterized in that said communication is put in contact with an air source via an obstruction member such as a non-return valve. 18. - Method according to claim 16 applied to an engine comprising at least two cylinders each of which comprises an exhaust pipe and an injection member, characterized in that at least one so-called cross communication is established connecting the pipe d exhaust from one of the cylinders or cylinder considered to the injection member of the other cylinder. 19. - Method according to claim 18 applied to an engine for which each of said cylinders comprises a pump housing and a transfer duct, characterized in that a part of the compressed gases coming from the pump housing of said cylinder considered is directed towards the member injection (12, 12a) of the same cylinder and combines with the gas from the communication between the exhaust pipe of the other cylinder to the injection member of the cylinder in question. 20. - Method according to claim 16 applied to an engine comprising at least two cylinders, at least one of these cylinders comprising a pump casing, a transfer duct, characterized in that part of the compressed gases coming from said pump casings is directed towards the injection member of another cylinder. 21. - Method according to claim 20 applied to an engine in which each cylinder comprises an exhaust manifold, characterized in that said communication connects the exhaust manifold of said other cylinder to the injection member of this same cylinder and in that at least a part of the compressed gases coming from said pump block is directed towards the injection member and combines with the gases coming from said communication.

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