WO2009000895A2

WO2009000895A2 - Fluid circulation pump with integrated short circuit

Info

Publication number: WO2009000895A2
Application number: PCT/EP2008/058198
Authority: WO
Inventors: Stéphane TONDELLI
Original assignee: Valeo Systemes Thermiques
Priority date: 2007-06-27
Filing date: 2008-06-26
Publication date: 2008-12-31
Also published as: FR2918128A1; FR2918128B1; WO2009000895A3

Abstract

Fluid circulation pump. According to the invention, said pump is a vibrating-diaphragm pump (33) comprising a pump body (10) and means (70) for short-circuiting said pump body (10). Switching means (71) are designed to select for said fluid a path which passes through said short-circuit means or a path which passes through said pump body (10). The invention can be applied to the recovery of exhaust gases or to the supercharging of internal combustion engines. (Figure 2)

Description

INTEGRATED SHORT CIRCULATION FLUID PUMP

The present invention relates to a fluid circulation pump. The invention finds an advantageous application in the field of exhaust gas recovery and overfeeding of internal combustion engines, particularly diesel engines and direct injection gasoline engines.

In this context, the term "fluid" is understood to mean both the exhaust gas and the intake air or a mixture of exhaust gas and intake air. Of course, the invention is not limited to these types of fluid, but extends to any fluid, whether liquid or gaseous. Most internal combustion engines, and more particularly diesel engines and direct injection engines, produce nitrogen oxides, referred to together as NOx, the effects of which on the environment are particularly harmful.

One known way to limit the production of nitrogen oxides is to recycle the exhaust gas. According to this technique, called EGR for "

Exhaust Gas Recovery ", at least a portion of the exhaust gas formed is taken from the exhaust manifold and mixed with the intake air upstream of the intake manifold. This mixture is then introduced into the combustion chamber of the engine. The presence of exhaust gas in the gas mixture has the effect of reducing the combustion temperature in the chamber, and as the formation of NOx is highly temperature dependent, it is understood that the recirculation of the exhaust gas helps to reduce the amount of nitrogen oxides formed. This effect increases with the amount of exhaust gas mixed with the intake air.

In certain known EGR architectures, a recovery duct is disposed between an exhaust duct downstream of the exhaust manifold and an inlet duct upstream of the distributor. intake. The circulation of the exhaust gases in the recovery duct is simply the result of the pressure difference existing between the inlet and the outlet of the duct. An adjustable valve, called a "metering device", is placed on the intake duct. upstream of the outlet of the recovery duct. When the metering device closes, a pressure drop is created at the outlet, which increases the pressure difference between the inlet and the outlet of the recovery duct, resulting in a simultaneous increase in the flow rate of the exhaust gas recovered. However, closing the dispenser also has the effect of reducing the amount of air intake and limiting the power available, it is then necessary to find a compromise between power and pollution.

U.S. Patent No. 6,062,026 provides a solution to this difficulty. According to the architecture described in this patent, the air intake duct comprises a double inlet adjustable valve into which also leads the exhaust gas recovery duct. This adjustable valve is capable of varying in varying proportions the composition of the air / exhaust gas mixture at the outlet of the valve, which is connected to the inlet distributor by means of a centrifugal pump. It is understood that this known architecture makes it possible to satisfy both the power requirements and the reduction of the quantity of nitrogen oxides formed by adapting to the mode of operation of the engine the composition of the mixture supplied by the valve and the flow rate of ia. pump. In particular, it is possible, particularly at low speed, to supercharge the engine by means of the centrifugal pump by closing the exhaust valve and opening it to the intake air.

The architecture described in the aforementioned US patent also provides a short circuit intended mainly to bypass the pump when it does not work, for example at high speed when a supercharging is not necessary, in order to avoid pressure losses. which could appear in the intake circuit due to the passage of the pump. The pumps used to circulate exhaust gases in known EGR architectures, such as the one just described, are mostly centrifugal pumps. However, this type of pump has a certain number of drawbacks which limit its performance.In particular, the centrifugal pumps are sensitive to the aggressive acid environment due to the presence in the exhaust gases of nitrogen oxides NOx but also of sulfur oxides which, in contact with the ambient humidity, are likely to form acids, nitric or sulfuric.These acidic products then attack the metal parts of the pumps.

Similarly, the exhaust gas loaded with soot can foul the blades of the pumps which are known that the operating clearances are very low and sensitive to fouling.

In addition, the temperature excursion of the centrifugal pumps is relatively low, less than 18O ⁰ C output, this because of their poor mechanical strength and the possibility of creep.

Finally, the relatively long response time, of the order of a few hundred milliseconds, of this type of pump is penalizing during transient engine conditions, because it must then be possible to vary very quickly the rate of recovered exhaust gas. and / or the quantity and the air flow at admission.

It should also be noted that the pump short circuit described in US Pat. No. 6,062,026 is a member external to the pump itself, which therefore requires specific assembly and is costly in both time and equipment.

Also, an object of the invention is to provide a fluid circulation pump, which would improve the performance of said architecture compared to known architectures centrifugal pumps, and avoid the disadvantages associated with the presence of a short circuit reported to the pump itself.

This object is achieved, according to the invention, because said pump is a vibrating membrane pump comprising a pump body, in which which is provided said membrane, and short circuit means of said pump body.

The pump according to the invention further comprises switching means adapted to select for said fluid a path passing through said short-circuit means or a path passing through said pump body.

Vibrating membrane pumps are described in International Application No. 97/29282.

Figure 1a is an exploded perspective view of a vibrating membrane pump according to the aforementioned international application. FIG. 1b is a side view of the vibrating membrane pump of FIG. 1a,

The pump of Figures 1a and 1b consists of a pump body 10 consisting of two flanges 31, 32 of rigid revolution between which is housed a deformable membrane 33 disk-shaped. This membrane is made for example of elastomer. The gases enter the pump body via a peripheral inlet orifice 27 and escape through an axial outlet orifice 29 formed on a 31 of said flanges.

A motor member, not shown, generates a cylindrical and symmetrical distribution of periodic excitation forces 34 applied to the peripheral end 35 of the membrane 33 on the side of the inlet orifice 27.

The membrane 33 then becomes the support of concentric waves which move from the edge 35 towards the center, this displacement being accompanied by the damping of the waves and the propulsion of the fluid.

The advantages of this type of pump are many. In the first place, it should be remembered that diaphragm pumps being made of a plastic material, they are much more resistant to the aggressive acidic environment than centrifugal pumps which are mainly metallic, and they also have a lower sensitivity to temperature. On the other hand, since the operating gaps are larger, the soot particles for example can pass through the pump without being held there, which avoids any risk of fouling. There is therefore no need to use particle filtration systems. (particulate filters, etc.). This advantage is increased by the fact that the oscillatory movement of the membrane can give the pump a self-cleaning character. It is even possible under these conditions to provide cleaning cycles.

It should also be noted that the moving parts of the diaphragm pumps have a low inertia, which means that the power to be developed at startup, or peak power, is lower. The withdrawal of power from the on-board network when the pump is put into service therefore does not affect the power supply to other parts of the vehicle. Similarly, the vibrating membrane pumps have a shorter response time, of the order of a few tens of milliseconds, with all the advantages that this represents in the transient regime.

Finally, mechanically, diaphragm pumps have fewer parts, which improves its reliability. The vibrating membrane pump which has just been described with reference to FIGS. 1a and 1b is thus completed, according to the invention, by means of short circuit of the pump body, integrated with the pump itself with all the advantages. cost and mounting resulting from it since the pump, object of the invention, can be implemented in all engine architectures without having to instail a specific short circuit outside the pump. The fluid can thus pass through the pump, either through the short circuit or through the body. There is thus a solution where, when the membrane is inactive, the fluid can pass through the pump without having to pass through the pump body, which allows, in particular, to reduce the loss of charge. Said pump may further comprise switching means adapted to select for said fluid a path passing through said short-circuit means or a path passing through said pump body.

According to a first embodiment of the invention, the pump body comprises: two flanges, in particular of revolution, between which is housed the vibrating membrane,

- a peripheral inlet,

an axial output orifice formed on a first flange, and said pump body is disposed in a chamber having an inlet opening opening on a second flange and an outlet opening extending said outlet of the first flange. Said short-circuit means comprise a central opening made in the second flange, and said switching means comprise a shutter means controllable from said central opening.

In a first example of implementation, said controllable shutter means is a valve adapted to close said central opening.

In a second example of implementation, said controllable shutter means is a piston movable in translation, adapted to close said central opening.

According to a second embodiment of the invention, the pump body comprises:

two flanges, in particular of revolution, between which is housed the vibrating membrane,

- a peripheral inlet,

an axial outlet orifice arranged on a first flange, and said pump body is disposed in a chamber having an inlet opening opening on a second flange and an outlet opening coaxial with said outlet orifice of the first flange. Said shorting means comprises a space for the passage of gases, formed between said outlet opening and said outlet opening, and said switching means comprise a controllable shutter means of said passage space. In an example of particular implementation, said controllable shutter means is a movable tubular in translation, adapted to connect said outlet opening to the outlet orifice of the first flask.

According to a third embodiment of the invention, the pump body comprises: two flanges, in particular of revolution, between which the vibrating membrane is housed,

- a peripheral inlet,

an axial output orifice formed on a first flange, and said pump body is disposed in a chamber having a lateral inlet opening opening to said peripheral inlet port, a first outlet opening extending said outlet port of the first flange and a second outlet opening. Said short-circuit means comprise a gas passage space between said inlet opening and the second outlet opening, and in that said switching means comprise controllable means for alternately closing the first and second outlet openings.

In these different embodiments, said chamber may also be provided with inlet and / or outlet ducts, respectively in communication with said inlet and / or outlet orifices.

As mentioned above, the gas circulation pump according to the invention can easily be integrated into various engine architectures. In particular, the invention relates to an architecture for recovering exhaust gas in an internal combustion engine, which is remarkable in that it comprises a circulation pump according to the invention for at least the said exhaust gases.

According to a first type of architecture where the diaphragm pump is dedicated to the exhaust gas recovery function only, said vibrating membrane pump is placed on an exhaust gas recovery pipe arranged between an exhaust pipe engine and an air intake duct.

However, the architecture which is the subject of the invention is not limited to exhaust gas recovery alone, it can also be used to supercharge the engine, in which case it is provided by the invention that the vibrating diaphragm pump is able to increase the mass flow of intake gas into the engine.

According to a second type of architecture in which the diaphragm pump is capable of providing both the exhaust gas recovery and the engine supercharging functions, an exhaust gas recovery duct being arranged between a duct engine exhaust and an air intake duct, said vibrating membrane pump is placed on said intake duct downstream of the outlet of the recovery duct in the intake duct.

Finally, the invention applies quite advantageously to engines having a turbocharger, the vibrating membrane pump being arranged in series with a compressor of a turbocharger.

In a first embodiment, said pump is placed downstream of said compressor, said recovery duct opening out of said exhaust duct upstream of the turbine of the turbocharger.

In a second form of implementation, said pump is placed upstream of said compressor, said recovery duct opening out of said exhaust duct downstream of the turbine of the turbocharger.

The following description with reference to the accompanying drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be achieved. Figure 2 is a side view of a first embodiment of a fluid circulation pump according to the invention.

FIG. 3 is a variant of the embodiment of FIG. 2.

Figure 4 is a side view of a second embodiment of a fluid circulation pump according to the invention. Figure 5a is a side view of a third embodiment of a fluid circulation pump according to the invention, in the pumping position;

Figure 5b is a side view of the circulation pump of Figure 5a, in the short-circuit position. Figure 6 is a diagram of an exhaust gas recovery architecture including a fluid circulation pump according to the invention.

FIG. 7a is a diagram of a first exhaust gas recovery architecture with supercharging including a fluid circulation pump according to the invention.

FIG. 7b is a diagram of a second supercharged exhaust gas recovery architecture including a fluid circulation pump according to the invention. Figure 8a is a diagram of a first architecture comprising a fluid circulation pump according to the invention in series with a compressor of a turbocharger.

Figure 8b is a diagram of a second architecture comprising a fluid circulation pump according to the invention in series with a compressor of a turbocharger.

FIG. 2 shows a fluid circulation pump comprising a vibrating membrane pump body 33 similar to that previously described with reference to FIGS. 1a and 1b. As shown in Figure 2, said pump body 10 is disposed in a chamber 60 having a fluid inlet opening 62 opening on the second flange 32 of the pump body 10. An outlet opening 61 of the chamber 60 is located substantially in the extension of the outlet orifice 29 of the first flange 31 of the pump body 10. The circulation pump shown in FIG. 2 further comprises short circuit means of the pump body 10 which, coupled to switching means, make it possible to select for the circulating fluid in the pump a path crossing the body of the pump. pump, ie a path avoiding the pump body by passing through said short-circuiting means In the embodiment of FIG. 2, said short-circuiting means comprise a central opening 70 made in the second flange 32, whereas said means switching means comprise a controllable shutter means constituted, in the example of Figure 2, by a valve 71 adapted to close said central opening 70.- The left part of Figure 2 corresponds to the case where the pump is active. The shut-off valve 71 is closed so that the fluid entering the chamber 60 is forced to enter the pump body through the inlet port 27 and exit through the chamber outlet opening 61 via the outlet port 29 of the pump body 10. The right part of FIG. 2 corresponds to the case where the pump is short-circuited. The shutoff valve 71 is open, allowing most of the fluid entering the chamber 60 to pass directly through the pump body through the central opening 70, avoiding the propulsion effect of the pump. Vibration membrane 33. The overall pressure drop of the pump between the inlet and outlet ducts of the chamber 60 is therefore lower in this configuration than if the fiuid were to pass inside the pump body.

FIG. 3 illustrates a variant of the pump of FIG. 2 in which said controllable switching means is constituted by a piston 72 movable in translation capable of closing off the central opening 70. For this purpose, the piston 72 moves in a bore 73 and has holes 74 so that, when the pump is active (right part of Figure 3), the piston is brought against the second flange 32 to close the central opening 70 and to penetrate the fluid entering the opening 62 of the chamber 60 into the pump body through the inlet port 27.

On the other hand, when the pump has to be short-circuited (left part of FIG. 3), the piston 72 is disengaged from the second flange 32 so as to extend the inlet opening 62. The fluid entering the chamber 60 is thus forced to pass through the holes 73 of the piston 72 and the central opening 70 to exit directly from the chamber 60 through the outlet orifice 29 of the pump body 10 and the outlet opening 61 of the room.

The embodiment shown in two variants in FIGS. 2 and 3 realizes the short circuit of the pump body 10 by direct axial passage of said pump body.

The embodiments of FIGS. 4 and 5a and 5b which will now be presented proceed bypassing the pump body.

In the embodiment illustrated in FIG. 4, the outlet orifice 29 of the first flange 31 and the outlet opening 61 of the chamber 60 are arranged so as to clear a passage space 63 for the fluid circulating in the chamber. 60. This passage space is a means of short-circuiting the pump body 10 when necessary. The switching between the active mode and the short-circuited mode of the pump is performed by a tubing 80 movable in translation, able to connect the outlet port 29 of the pump body 10 to the outlet opening 61 of the chamber 60 .

When the pump is active (left side of Figure 4), the tubing 80 closes the passage space 63, the fluid entering the chamber 60 must then enter the pump body through the inlet port 27. On the other hand, a short circuit of the pump (right-hand part of FIG. 4) bypassing the pump body 10 is obtained by disengaging the tubing 80 from the fluid passage space 63.

According to the embodiment of Figures 5a and 5b, the chamber 60 has a lateral inlet opening 62 opening on the peripheral inlet port 27 of the pump body, a first fluid outlet opening 61 is located in the extension of the outlet orifice 29 of the first flange 31 and a second outlet opening 64.

As can be seen in FIGS. 5a and 5b, the means for short-circuiting the pump is provided by a space 90 for passage of the fluid between the inlet opening 62 and the second opening. 64 output. Switching between the path passing through the pump body and the short-circuiting path is achieved by controllable valves 91, 92 for alternately closing the outlet openings 64, 61 of the chamber 60. FIG. 5a shows the configuration active pump in which the valve 91 is closed and the valve 92 open. The fluid entering the chamber 60 through the inlet opening 62 penetrates through the inlet orifice 27 into the pump body 10 where it benefits from the propulsion effect of the membrane 33 and then exits through the orifice 29 output and the opening 61 output. In the short-circuited mode of the pump, shown in FIG. 5b, the valve 92 is closed and the valve 91 open. The fluid can thus avoid the pump cops directly through the passage space 90 between the inlet opening 62 and the second outlet opening 64.

In practice, it is possible to make only one outlet opening by connecting the openings 61 and 64 downstream.

We will now describe various architectures of internal combustion engines inducing a fluid circulation pump according to the invention.

FIG. 6 shows an architecture for recovering exhaust gas in an internal combustion engine 100, comprising an air intake duct 20 connecting an air inlet 200 to an inlet distributor 110, and a 30 exhaust duct for driving the gases exhaust system leaving an exhaust manifold 120 to an outlet 300.

As can be seen in the architecture of FIG. 6, an exhaust gas recovery duct 40 is disposed between the exhaust duct 30 and the intake duct 20. In order to be able to increase the mass flow rate of the recovered gases and to extend the possibilities of recovering the engine in exhaust gas, a vibrating membrane pump 1 is placed on the recovery duct 40. In addition, an exhaust gas flow control valve 41 is connected in series with the pump body 10 to the recovery conduit 40 in order to adjust the amount of gas recovered. Optionally, a recovered exhaust gas cooling circuit 21 is installed on the inlet duct 20 upstream of the inlet distributor 110.

FIG. 6 also shows the presence of a metering device 50 placed on the inlet duct 20 upstream of the outlet of the recovery duct 40 in the intake duct 20. The role of this metering device 50 is to allow the adjustment of the mass flow rate of the air supplied to the input splitter 110 of the motor 100.

Finally, as shown in FIG. 6, a short-circuit 11 is placed in parallel with the pump body, a switching valve 12 making it possible to select for the circulation of the exhaust gases, ie the path passing through the pump body 10. , or the path through the short circuit 11. This avoids the pressure drops due to the pump 1 when it does not work. Of course, the functions of the valves 41 and 12 could be realized by a single valve.

In the architecture of FIG. 6, the recovery circuit is independent of the operation of the motor, the pump 1 only being intended for recovering the exhaust gases. Conversely, FIGS. 7a and 7b illustrate two architectures where the pump

1 can also be used to supercharge the motor by increasing the mass flow rate of the air at the inlet, this simultaneously or separately from the recovery function. For this purpose, the pump 1 is placed on the intake duct 20 downstream of the outlet of the recovery duct 40 in the intake circuit 20.

As in the example of FIG. 6, a control valve 41 is placed on the recovery duct 40 in order to be able to vary the flow rate of the recovered gases, and thus to modify at will the quantity of the admitted gases and their proportion. It is thus possible to adapt the operation of the pump according to the operating phases of the motor.

FIGS. 7a and 7b show more specifically two architectures in which a short-circuit 11 is placed in parallel with the pump body, a switching valve 12 making it possible to choose a flow path for the gases passing through the pump body 10 or short circuit 11.

As mentioned above, the main function of the short circuit 11 is to avoid pressure drops across the pump 10 when it is stopped, and to prevent the return of gases to the inlet when it is running.

In FIG. 7a, the exhaust gas recovery duct 40 opens into said air intake duct 20 upstream of the short-circuit 11. In FIG. 7b, the exhaust gas recovery duct 40 opens in the air intake duct 20 upstream of the pump body 10, in the path passing through the pump. This second configuration has the advantage of allowing the integration of the pump body, the short-circuit 1 1, the switching valve 12 and the control valve 41 into a single component 1.

The following description is specifically for engines equipped with a turbocharger 400.

Figures 8a and 8b relate to so-called "series" architectures where the diaphragm pump 1 is arranged in series with the compressor 410 of the turbocharger 400.

More particularly, in the architecture of FIG. 8a, the pump 1 is placed downstream of the compressor 410, whereas the recovery duct 40 opens out from the exhaust duct 30 upstream of the turbine 420, that is to say say in an area of high pressure, and in the intake duct 20 downstream of the compressor 410, also in a high pressure zone, hence the name of "high pressure" given to this architecture.

A cooler 22 can be placed between the turbocharger 400 and the pump 1. In the architecture of FIG. 8b, the pump 1 is placed upstream of the compressor 410, whereas the recovery conduit 40 opens out of the exhaust pipe 30. downstream of the turbine 42O ₁ that is to say in a low pressure zone, and in the inlet duct 20 upstream of the compressor 410, also in a low pressure zone, hence the name "low pressure "given to this architecture.

Claims

A fluid circulation pump, characterized in that said pump (1) is a vibrating membrane pump (33) comprising a pump body (10), in which said diaphragm is provided, and short circuit means of said pump body (10) dθ pump.

2. Pump according to claim 1, further comprising switching means adapted to select for said fluid a path through said short-circuit means or a path through said body (10) pump.

3. Pump according to claim 2, characterized in that, the pump body (10) comprising;

two flanges (31, 32) between which the vibrating membrane (33) is housed; a peripheral entry orifice (27);

- An orifice (29) for axial output on a first flange (31), said pump body (10) is disposed in a chamber (60) having an inlet opening (62) opening on a second flange (32). and an outlet opening (61) extending said outlet orifice (29) of the first flange (31), in that said short-circuit means comprise a central opening (70) made in the second flange (32), and said switching means comprise means (71, 72) for shutting off said central opening (70).

4. Pump according to claim 3, wherein said controllable shutter means is a valve (71) adapted to close said central opening (70).

5. Pump according to claim 3, wherein said controllable shutter means is a movable piston (72) in translation, adapted to close said central opening (70).

6. Pump according to claim 1, characterized in that the pump body (10) comprising:

two flanges (31, 32) between which the vibrating membrane (33) is housed,

a peripheral entry orifice (27), an axial outlet orifice (29) formed on a first flange (31), said pump body (10) is arranged in a chamber (60) having an inlet opening (62) opening on a second flask (32); and an outlet opening (61) coaxial with said outlet orifice (29) of the first flange (31), in that said short-circuiting means comprise a space (63) for the passage of gases, formed between said orifice (29); ) and said outlet opening (61), and in that said switching means comprises a controllable shutter means (80) of said passage space.

7. Pump according to claim 6, wherein said controllable shutter means is a movable tubular (80) in translation, adapted to connect said outlet opening (61) to the outlet orifice (29) of the first flange (31). ).

8. Pump according to claim 2, characterized in that, the body (10) comprising: - two flanges (31, 32) between which is housed the vibrating membrane (33),

a peripheral entry orifice (27),

- an orifice (29) for axial output on a first flange (31), said pump body (10) is disposed in a chamber (60) having a lateral inlet opening (62) opening on said opening (27) a first exit aperture (61) extending said outlet port (29) of the first flange (31) and a second exit aperture (64), in that said short circuit means comprises a gap (61); 90) between said inlet opening (62) and the second outlet opening (64), and in that said switching means comprise controllable means (91, 92) for alternately closing the first (61) ) and second (64) outlet openings.

9. Exhaust gas recovery architecture in an engine (100) with internal combustion, characterized in that it comprises a pump (1) for circulation according to any one of claims 1 to 7 for at least said gas d 'exhaust.

10. Architecture according to claim 9, wherein said pump (1) with vibrating membrane (33) is placed on a conduit (40) for recovery of exhaust gas disposed between an exhaust duct (30) of the engine and an air intake duct (20).

11, Architecture according to claim 9, wherein the pump (1) vibrating membrane is adapted to increase the mass flow rate of intake gas in the engine (100).

12, architecture according to claim 11, wherein, an exhaust gas recovery duct (40) being disposed between an exhaust duct (30) of the engine and an air intake duct (20), said duct pump (1) vibrating membrane is placed on said duct (20) intake downstream of the outlet of the conduit (40) recovery in the conduit (20) intake.

13, Architecture according to claim 12, wherein said duct (40) of exhaust gas recovery opens into said duct (20) for admission of air upstream of the short-circuit means (11),

14. Architecture according to claim 12, wherein said conduit (40) for recovering exhaust gas opens into said duct (20) of air intake upstream of the pump (1) in the path through the pump.

15. Architecture according to any one of claims 12 to 14, wherein the vibrating membrane pump (1) is arranged in series with a compressor (410) of a turbocharger (400).

16. Architecture according to claim 15, wherein said pump (1) is placed downstream of said compressor (410), said recovery duct (40) opening out of said exhaust duct (30) upstream of the turbine (420) of the turbocharger.

17. Architecture according to claim 15, wherein said pump (1) is placed upstream of said compressor (410), iedit conduit (40) of recovery emerging from said conduit (30) of exhaust downstream of the turbine (420) of turbocharger.