EP0192010A1 - Apparatus and method 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 the other to an injection member (12) .

Description

The present invention relates to a device and a method allowing and / or improving the injection of fuel assisted by air or compressed gases, or pneumatic injection on an internal combustion engine. The present invention can be applied to four-stroke engines and two-stroke engines, in particular those 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 escapes into the atmosphere before the exhaust ports are closed. Hence a significant reduction in yield and high emissions of pollutants.

The injection of fuel by assisted air from the crankcase overcomes this drawback. An example has been proposed by Mr. J.A. CULMANN in French patent FR-490.166. According to this patent, the cylinder is scanned with only air coming from the pump housing, another part of the air from the pump housing is introduced, under a pressure close to the maximum pressure reached in this housing, 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 assist in pneumatic injection. 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 manifold. It is characterized in that the engine comprises a pipe which will be called auxiliary having two ends or openings, one being connected to said exhaust pipe and the other to said injection member.

The engine may include a pump casing and 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 this chamber injection may include 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 a pipe and an injection member. In this case, the engine may also include at least one cross auxiliary pipe, connecting the exhaust pipe of one of the cylinders to the injection member of the other cylinder.

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.

The present invention can be applied to an engine comprising several cylinders, at least one of which comprises an exhaust pipe and the other a pneumatic member. In this case, an auxiliary pipe can connect the exhaust pipe to the pneumatic injection member.

If this engine is an engine whose cylinders include a pump casing, it may also include at least two injection chambers, each of which connects the pump casing of one of the cylinders, or cylinder in question, 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 multi-cylinders, 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 performing the injection of fuel into an internal combustion engine equipped with a pneumatic injection member and an exhaust pipe. This method is characterized in that communication is established between the exhaust pipe and the injection member.

This process can be applied to an engine comprising a pump casing. In this case, part of the compressed gases coming from the pump casing is directed towards the injection member and combines with the gases coming 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,
• - la figure 1A montre un mode de réalisation de l'invention,
• - les figures 2 à 6 illustrent le fonctionnement du moteur selon la figure 1,
• - les figures 7, 8, 8A et 9 représentent des variantes de réalisation, et
• - les figures 10, 11, 12, 12A et 13 représentent des exemples d'applications particuliers dans le cas de moteurs multicylindres.

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,
• FIG. 1A shows an embodiment of the invention,
• FIGS. 2 to 6 illustrate the operation of the engine according to FIG. 1,
• FIGS. 7, 8, 8A and 9 show alternative embodiments, and
• - Figures 10, 11, 12, 12A and 13 show examples of particular 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 11 a 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 a 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 17 of volume V through an orifice 18 equipped 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 17 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 ₁ 7 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 the upper dead bridge 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 casing 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 the cylinder head 2 by compressing the air contained in the casing 3 which causes the valve 11a to close. When the pressure is higher than 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 17, 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 circuit) is introduced into the chamber 17, the pressure 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 19 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 ₁ 4 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 11a 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.

More generally, the same device can also operate and give sufficient pressure for injection by eliminating the communication 18, the chamber 17 and the valves ₁ 9 (Fig. 1A).

The operation of such a device is similar to that described above with reference to FIGS. 2 and ₄ . It is enough to delete in this description which relates to the communication 18 and to the chamber 17.

It will not depart from the scope of the present invention by applying the invention to a four-stroke engine or to a two-stroke engine having or not 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.

More generally, the same device can also operate by eliminating the sealed chamber 17 and the opening 18 (FIG. 8A).

The operation of this embodiment is the same as that described above.

The location 26 (whether in the case of FIG. _{1 as} well as in that of FIGS. 8 and 8A) 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 6 (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, the sealed chambers 17, 17a, 17b Evou ₁ 7c may be supplied by the casing 3, 3a, 3b and / or 3c of the cylinder in which they inject air case of Figures 12 and optionally one or 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 the injection into a cylinder could in fact be connected - (communication 26) to the tubing exhaust 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.

The variant of FIG. 12A represents a more general case than that of FIG. 12. In fact, according to this variant, the communications 18a and 19a with the pump casing as well as the lower part of the sealed chamber 17 have been eliminated, only one remains. a conduit connecting the exhaust pipe 16a of a cylinder 3 and the injection member of another cylinder 12. This communication pipe which corresponds to what has been previously designated by auxiliary pipe, may or may not include a non-return valve 22.

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.

Figure 13 shows the case of a chamber ₁ 7 '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 (11)

1. - Internal combustion engine comprising at least one pneumatic fuel injection member (12), at least one exhaust pipe (16), characterized in that it comprises at least one auxiliary pipe (20) having two ends or openings, one of which is connected to said exhaust pipe (16) and the other to said injection member (12). 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. - Engine according to claim 1, characterized in that said auxiliary pipe (20) has a third opening (23) opening onto a gas 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 ( ₁ 6) has the shape of a convergent whose section decreases going from the exhaust manifold ( ₁ 6) 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, characterized in that it comprises at least one auxiliary auxiliary pipe connecting the exhaust pipe of the one of the cylinders to the injection member of the other cylinder. 7. - Engine according to claim 6 comprising at least two cylinders each of which comprises an exhaust pipe and an injection member, characterized in that that it comprises 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. 8. - Engine according to claim 1 comprising several cylinders, at least one of which comprises an exhaust pipe and another one a pneumatic injection member, characterized in that it comprises an auxiliary pipe connecting said exhaust pipe to said injection organ. 9. - Method for injecting fuel into an internal combustion engine equipped with a pneumatic injection member and an exhaust pipe, characterized in that communication is established between the pipe exhaust and the injection device. 10. - Method according to claim 9, characterized in that said communication is put in contact with a gas source via an obstruction member such as a valve or a non-return valve. 11. - Method according to claim 9 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.

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