EP1859128B1 - Device for boosting the induction of recirculating gas in the intake duct of an internal combustion engine - Google Patents

Abstract

The invention relates to a device for the recirculation of gas in an intake duct (12) of an internal combustion engine, comprising a convergent/divergent-type structure (18) for the reinduction of recirculating gas (42), which is disposed in the duct (12), thereby defining a main intake flow area in the duct (12) and a reinduction flow area. The reinduction structure (18) comprises at least one opening (40) which extends in the direction of flow in the duct, such as to communicate the two flow areas.

Description

The present invention relates to a device for amplifying the suction of recirculating gas in the intake duct of an internal combustion engine. These recirculating gases may for example be crankcase gases (of the English "blow-by gas", hereinafter "crankcase gas") or exhaust gas (or gas EGR, English " exhaust gas recirculation ").

Initially, the crankcase gases, which come from leaks at the piston rings in the cylinder, were released into the atmosphere without special treatment. It is now mandatory to burn them before rejecting them.

Many devices have been proposed to burn these gases, in particular by making them recirculate in the engine air intake circuit.

In particular, the document US 5,611,204 discloses a device for suction of these crankcase gases in a supply circuit of a turbocharged diesel engine. According to this device, the crankcase gases are sucked into the supply circuit between the turbocharger and the intake manifold. In order to improve the suction of the crankcase gases, the supply duct is divided, locally, into a main duct and a bypass duct of smaller section. In this bypass duct, a venturi is arranged in such a way that the suction tap of the casing gases opens at the throat of the venturi. Thus, according to the Venturi effect, the speed of the intake gas increases while their pressure decreases, thus favoring the suction of the crankcase gases at this groove.

Moreover, the document US 4,150,646 discloses a substantially equivalent device for recirculating exhaust gas in a turbocharged diesel engine. In order to improve the suction of the exhaust gases, a venturi and a rotary valve are mounted in parallel in the duct, locally expanded, engine intake. The suction connection of the exhaust gas opens at the throat of the venturi. A control device, connected to the valve, controls the closure of the valve when the pressure in the inlet pipe upstream of the venturi is greater than a threshold value, and the opening of the same valve in the opposite case.

These devices, however, have the disadvantage of being intrusive and therefore of disturbing the flow of air in the intake circuit which causes inconvenience in the driving of the vehicle, in particular pressure losses. engine. In addition, these devices are inefficient because they are mounted on a pressure circuit conduit, which does not properly suck the recirculating gas.

Another device for recirculating gas is known from the document WO 01/51799 A .

The object of the invention is to propose a device making it possible to improve the suction of the recirculating gases in the feed circuit, in particular at low speed, while at the least disturbing the flow of air in the intake duct as little as possible. .

This object is achieved by means of a gas recirculation device in an intake duct of an internal combustion engine, the device comprises a recirculating gas recirculation structure, of convergent / divergent type, arranged in the duct. for defining a main intake flow section in the duct and a re-suction flow section, said re-suction structure having at least one opening extending in the direction of flow in the duct, said at least one opening communicating the two flow sections.

Thus, advantageously, the air flow is divided into two parts that can interact because of the presence of the at least one opening. Thus, the depression is greater, especially at low speeds, when the air flow is low. In addition, the at least one opening facilitates the manufacture of the device.

Preferably, an inlet adapted to cooperate with a gas recirculation pipe is provided in said intake duct, substantially at the converging / diverging transition of the rebreathing structure.

Thus, advantageously, the re-aspiration is even more effective, since it is at the level of the transition that depression is the most important and therefore the re-aspiration is most effective. In addition, the recirculating and recirculated gases can be mixed with the gases of the main flow progressively over the entire length of the divergent.

Preferably, said at least one opening is formed by an axial slot in said structure.

Thus, advantageously, the construction of the device is facilitated.

Preferably, said rebreathing structure is formed by means of at least two fins extending substantially along the axis of the intake duct on either side of said axial slot.

Thus, advantageously, the device according to the invention is not very intrusive, the fins being very thin, and easy to achieve.

Preferably, said at least two fins have a height of between 5 and 10% of the diameter of the intake duct, the distance between the two fins varying along the axial slot from 90 to 25% and then from 25 to 90% the diameter of the intake duct.

Thus, advantageously, a good compromise is reached between the efficiency of the venturi effect, the flow disturbances caused by the device and the ease, and therefore the cost, of the manufacture of the device.

Preferably, said at least two fins have a height of between 3 and 5 mm, the distance between the two fins varying along said axial slot from 55 mm to 15 mm and then from 15 mm to 55 mm, the diameter of the duct. intake being 60 mm.

We thus achieve a very good compromise between the efficiency of the venturi effect, the intrusion and the cost of manufacture in the case of a motor vehicle.

Preferably, said at least two fins and said intake duct are integrally formed by molding.

Thus, advantageously, the device is easy to produce.

According to a first preferred embodiment, said device is made of injected thermoplastic.

It is thus possible to make fins of greater height which make the device according to the invention more effective.

According to another preferred embodiment, said device is made of rubber.

Thus, advantageously, it is possible to mold the device at the same time as the entire air intake duct of the vehicle.

The invention also relates to a crankcase recirculation circuit incorporating a device according to the invention, which is remarkable in that it comprises a crankcase gas recirculation duct opening into said intake duct at the level of the convergent transition. / diverging from said re-suction device.

The invention also relates to an exhaust gas recirculation circuit (or exhaust gas recirculation (EGR) circuit incorporating a device according to the invention, which is remarkable in that it comprises an exhaust gas recirculation duct opening into said intake duct at the convergent / divergent transition of said re-suction device.

• la figure 1 représente schématiquement en vue en coupe selon B-B un premier mode de réalisation d'un dispositif selon l'invention ;
• la figure 2 représente schématiquement le dispositif de la figure 1 selon la coupe A-A ;
• la figure 3 représente schématiquement un second mode de réalisation d'un dispositif selon l'invention selon la coupe C-C ;
• la figure 4 représente schématiquement le dispositif de la figure 3 selon la coupe D-D ;
• la figure 5 représente schématiquement un système d'admission d'air d'un moteur turbocompressé muni d'un dispositif selon l'invention du type illustré aux figures 3 et 4 ;
• la figure 6 représente schématiquement un système d'admission d'air d'un moteur atmosphérique muni d'un dispositif selon l'invention du type illustré aux figures 3 et 4 ;
• la figure 7 représente schématiquement un système d'admission d'air d'un moteur atmosphérique muni d'un dispositif comme illustré aux figures 3 et 4.

Other features and advantages of the present invention will appear from the examination of the description which follows, presented solely by way of nonlimiting example with reference to the appended figures in which:

• the figure 1 shows schematically in sectional view according to BB a first embodiment of a device according to the invention;
• the figure 2 schematically represents the device of the figure 1 according to section AA;
• the figure 3 schematically represents a second embodiment of a device according to the invention according to the section CC;
• the figure 4 schematically represents the device of the figure 3 according to the DD section;
• the figure 5 schematically represents an air intake system of a turbocharged engine provided with a device according to the invention of the type illustrated in FIGS. Figures 3 and 4 ;
• the figure 6 schematically represents an air intake system of an atmospheric engine provided with a device according to the invention of the type illustrated in FIGS. Figures 3 and 4 ;
• the figure 7 schematically represents an air intake system of an atmospheric engine provided with a device as illustrated in FIGS. Figures 3 and 4 .

It should be noted that the proportions are not respected in the drawings in order to make more visible the device according to the invention and its remarkable elements.

On the figure 1 , we can see a first embodiment of a device 10 according to the invention comprising all or part of the intake duct 12. This intake duct 12 comprises an orifice 14, cooperating here with a nozzle 16 of a duct recirculating gas recirculation, in this case crankcase gases or EGR gases. A convergent / divergent type structure 18 forming a convergent 20 and a divergent 22 is disposed in the portion 12 of the intake duct, so that the orifice 14 faces the convergent transition 24 / diverge.

• une section d'écoulement de réaspiration 26, délimitée par la structure à convergent/divergent 18 ;
• une section d'écoulement principal d'admission 28, section complémentaire à la section d'écoulement de réaspiration 26 dans le conduit 12.

The convergent / divergent type structure 18 defines two sections 26, 28 in the intake duct 12:

• a re-aspiration flow section 26 delimited by the convergent / divergent structure 18;
• a main intake flow section 28, a section complementary to the re-suction flow section 26 in the conduit 12.

Intake duct 12 is traversed by an incoming flow of fresh air 30 diagrammatically represented by arrow 30. This flow 30 entering duct 12 is divided between the two sections 26, 28 of duct 12 to give a re-suction flow. 32 in the re-suction flow section 26, and a main intake flow 34, in the main intake flow section 28.

The structure 18 will be described in more detail with reference to the figure 2 , which schematically represents a section of the device of the figure 1 , according to the cutting plane AA. On this figure 2 , it can be noted that the structure 18 is made by means of two fins 36, 38, in this case formed integrally with the intake duct 12 and the tip 16 and which extend substantially in the direction of the axis xx 'of the duct 12. According to the embodiment presented on this figure 2 , the two fins 36, 38 are arranged symmetrically with respect to the plane (xx ', yy') and are substantially inclined towards one another. This figure 2 also illustrates the presence of an opening 40 extending between the two fins 26, 27, substantially in the direction of the flow 30, direction almost identical to those of the partial flows 32 and 34, shown in FIG. figure 1 parallel to the axis xx '. This opening 40 thus forms a slot in the convergent / divergent structure 18.

The re-suction flow 32 is accelerated in the convergent 20 while the pressure of the gaseous mixture flowing in the re-suction flow section 26 decreases as this gaseous mixture flows into the convergent 20 from the widest part of the converge towards the narrowest part of the convergent 20. Furthermore, part of the main intake flow 34 (its upper part shown figure 1 ) can mix with the re-suction flow 32. However, most of this main intake flow 34 (its lower part shown figure 1 ) undergoes practically no disturbance due to the presence of the structure 18.

At low speed, the convergent / divergent structure 18 makes it possible to implement the venturi effect of simultaneous acceleration and depression of the re-suction flow 32 to promote the re-aspiration of the recirculating gases 42 at the level of the convergent / divergent transition. 24.

Moreover, the main intake flow 34 is relatively undisturbed by the device 10 and the engine head losses are reduced at high speed.

Another advantage of achieving the converging / diverging type structure 18 by two fins 36, 38 is the ease of manufacture. Indeed, in this case, the intake duct being made of rubber, it is possible to mold the fins together with the rest of the duct and thus to obtain fins having a height of up to 3 mm.

However, depending on the size and configuration of the intake circuit and in order to maintain the desired efficiency of the device 10, the fins 36, 38 may have a height of about 5 mm. An advantageous embodiment then consists in molding, apart from the device 10, consisting of the conduit 12, the tip 16 and the convergent / divergent type structure 18, made of injected thermoplastic and connecting it to the upstream and downstream parts. downstream of the intake duct by means of, for example, clamps.

The Figures 3 and 4 show a second embodiment of the device according to the invention.

In a similar manner to the first embodiment, the device 50 comprises all or part of the intake duct 52. This intake duct 52 comprises an orifice 54, cooperating, in this case, with a nozzle 56 of a duct. Recirculating gas recirculation (in this case, crankcase gases or EGR gases). A convergent / divergent type structure 58 forming a convergent 60 and a divergent 62 is disposed in the intake duct 52, so that the orifice 54 faces the convergent / diverging transition 64.

The convergent / divergent structure 58 defines in the conduit 52 a re-suction flow section 66, located within the convergent / divergent structure 58, and a main intake flow section 68, composed of the remainder of the duct section 52.

The intake duct 52 is traversed by an incoming flow of fresh air 70 shown schematically by the arrow 70. This incoming flow 70 entering the duct 52 is divided between the two sections 66, 68 of the duct 52 to give a flow of re-aspiration 72, in the re-suction flow section 66, and a main intake flow 74, 76, in the main intake flow section 68.

The convergent / divergent structure 58 is made by means of two fins 78, 80, in this case formed integrally with the intake duct 52 and the nozzle 56 and which extend substantially along the axis xx 'of the duct 52. The two fins 78, 80 are substantially parallel to each other in the plane (yy', zz ') and leave a opening 82 between them, the opening 82 extending substantially in the direction of the flow 70, direction almost identical to those of the partial flows 72 and 74, 76, shown on the figure 3 parallel to the axis xx ', thus forming a slot in the convergent / divergent structure 58. The two embodiments presented here (inclined fins 36, 38 and parallel fins 78, 80) are equivalent from a technical point of view . However, the parallel fin embodiment is easier to manufacture in practice.

Moreover, the two fins 78, 80 have, in the plane (xx ', yy'), a curved profile approaching and then moving away from the axis xx ', thus realizing the convergent 60 and the divergent 62, the fins 78, 80 represented figure 3 presenting, by way of illustrative and nonlimiting example, a parabolic profile.

The re-aspiration flow 72 is accelerated in the convergent 60 while the pressure of the gaseous mixture flowing in the re-suction flow section 66 decreases as this gaseous mixture flows into the convergent 60 from the widest part of the converge 60 towards the narrowest portion of the convergent 60. In addition, a portion of the main intake flow 74, 76 can mix with the re-aspiration flow 72. However, most of this main flow of admission 74, 76 undergoes virtually no disturbance due to the presence of the convergent / divergent structure 58.

At low speed, the convergent / divergent structure 58 makes it possible to implement the venturi effect of simultaneous acceleration and depression of the re-aspiration flow 72 to promote the re-aspiration of the recirculating gases 84 at the level of the convergent / divergent transition. 64.

Furthermore, the main intake flow 74, 76 is relatively undisturbed by the device 50 and the engine head losses are reduced at high speed.

In a similar manner to the first embodiment, the device 50 can be made simply by molding the intake duct 52, in this case made of rubber, which makes it possible to obtain fins 78, 80 having a height of up to 3 mm.

However, depending on the size and configuration of the conduit 52 and to maintain the desired efficiency of the device 50, the fins 78, 80 may have a height of about 5 mm. An advantageous embodiment then consists in molding, apart, the device 50 consisting of the conduit 52, the tip 56 and the convergent / divergent type structure 58, injected thermoplastic. We can then connect the device 50 to the upstream and downstream portions of the intake duct by means of, for example, clamps 86, 88 as shown in FIG. figure 7 . On this figure 7 , the device 50 has been mounted between a flowmeter 90 and a throttle body 92 of an air intake circuit 94 of an atmospheric engine. This air intake circuit 94 also comprises an air intake scoop 96 and an air filter 98 mounted between the scoop 96 and the flow meter 90.

• la distance L entre les ailettes à l'entrée du convergent est de 55 mm,
• la distance l entre les ailettes au niveau de la transition 54 convergent/divergent est de 15 mm,
• la hauteur h des ailettes est égale à 5 mm et
• où le diamètre d du conduit d'admission d'air est de 60 mm

(cf. figures 3 et 4), le dispositif 50 permettrait de réduire la pression de 60% dans le carter inférieur pour un régime moteur de 1250 tr/min.As an illustrative and nonlimiting example, it is estimated that, in the particular case where:

• the distance L between the fins at the entrance of the convergent is 55 mm,
• the distance 1 between the fins at the convergent / divergent transition 54 is 15 mm,
• the height h of the fins is equal to 5 mm and
• where the diameter d of the air intake duct is 60 mm

(Cf. Figures 3 and 4 ), the device 50 would reduce the pressure of 60% in the sump for an engine speed of 1250 rpm.

These quantities may be related to the diameter d of the intake duct 52, values which characterizes the size of the device 50. In this case, the height h is between 5 and 10% of the diameter d. The distance between the two fins 78, 80 varies between about 90% of d, at the inlet of the convergent 60 and the outlet of the divergent 62, and 25% of d, at the level of the convergent / divergent transition 64.

The Figures 5 and 6 represent advantageous mounting arrangements of the device 50 respectively in the case of a turbocharged engine and in the case of an atmospheric engine.

On the figure 5 , an air intake system 100 of a turbocharged engine is partially and schematically shown. The air is admitted into the system 100 at the inlet scoop 102 and is then filtered in the air filter 104. A flow meter 106 makes it possible to measure the flow rate of the air flow at the outlet of the The device 50 is disposed downstream of this flow meter 106 and upstream of the turbocharger 108 while the air flow is low. The air flow is thus undisturbed by the re-aspiration of the recirculating gases represented by the arrow 110.

On the figure 6 , an air intake system 112 of an atmospheric engine is partially and schematically shown. The air is admitted into the system 112 at the inlet scoop 114 and is then filtered in the air filter 116. A flow meter 118 makes it possible to measure the flow rate of the air flow at the outlet of this filter 116. Upstream of a throttle body 120 and downstream of the flowmeter 118, the device 50 allows the recirculation of the recirculating gases represented by the arrow 122. Here again, the air flow rate is lower in this part of the system. admission, the re-aspiration of the recirculating gases and the presence of the device 50 disturbs less the flow and therefore does not create engine losses.

Of course, the advantageous arrangements for mounting the device 10 correspond to those of the device 50 which have just been described.

Moreover, the present invention is not limited to the cases presented, provided by way of illustrative and non-limiting examples.

In addition, the realization of the convergent / divergent type structure is not limited to the case of the two fins. Many other embodiments are possible, such as the implementation of ribs, plates or platelets, metal or plastic.

Furthermore, the use of the device is suitable both for a crankcase air recirculation air intake circuit and an exhaust gas recirculation air intake circuit, without modification of the device. .

Claims (11)

1. Device for recirculating gas in an intake duct (12, 52) of an internal combustion engine, the device comprising a structure (18, 58) for reaspirating recirculating gas (42, 84), of the convergent/divergent type, positioned in the duct (12, 52) to define a main intake flow section (28, 68) in the duct (12, 52) and a reaspiration flow section (26, 66), characterized in that the said reaspiration structure (18, 58) comprises at least one opening (40, 82) extending in the direction of flow along the duct (12, 52), the said at least one opening (40, 82) causing the two flow sections (26, 28, 66, 68) to communicate.
2. Device according to Claim 1, characterized in that it comprises an inlet port (14, 54) capable of collaborating with a gas recirculation pipe provided in the said intake duct (12, 52) substantially at the convergent/divergent transition (24, 64) of the reaspiration structure (18, 58).
3. Device according to one of Claims 1 and 2, characterized in that the said at least one opening (40, 82) is formed of an axial slit in the said reaspiration structure (18, 58).
4. Device according to Claim 3, characterized in that the said reaspiration structure (18, 58) is produced by means of at least two fins (36, 38, 78, 80) extending substantially along the axis of the intake duct on each side of the said axial slit.
5. Device according to Claim 4, characterized in that the said at least two fins (36, 38, 78, 80) have a height ranging between 5 and 10% of the diameter of the intake duct, the distance between the two fins varying along the axial slit from 90 to 25% then from 25 to 90% of the diameter of the intake duct.
6. Device according to Claim 5, characterized in that the said at least two fins (36, 38, 78, 80) have a height ranging between 3 and 5 mm, the distance between the two fins (36, 38, 78, 80) varying along the said axial slit from 55 mm to 15 mm then from 15 mm to 55 mm, the diameter of the intake duct (12, 52) being 60 mm.
7. Device according to one of Claims 4 to 6, characterized in that the said at least two fins (36, 38, 78, 80) and the said intake duct (12, 52) are formed as a single piece, by moulding.
8. Device according to Claim 7, characterized in that the said device (10, 50) is made of injection-moulded thermoplastic.
9. Device according to Claim 7, characterized in that the said device (10, 50) is made of rubber.
10. Blow-by recirculation circuit incorporating a device (10, 50) according to any one of the preceding claims, characterized in that it comprises a blow-by recirculation duct opening into the said intake duct (12, 52) at the convergent/divergent transition (24, 64) of the said reaspiration device (18, 58).
11. Exhaust gas recirculation circuit incorporating a device (10, 50) according to any one of Claims 1 to 9, characterized in that it comprises an exhaust gas recirculation duct opening into the said intake duct (12, 52) at the convergent/divergent transition (24, 64) of the said reaspiration device (18, 58).

Images