EP1019627B1 - Jet pump comprising a jet with variable cross-section - Google Patents

Description

The present invention relates to the field of jet pumps.

The present invention finds in particular, but not exclusively, application in the field of tanks motor vehicle fuel.

Even more precisely the present invention can find application in fuel transfer between different pockets for fuel tanks multipockets, or for filling a reserve bowl which draws a fuel pump or any other fuel supply device.

Examples of suction devices from jet pump fuel are shown in the documents DE-A-3 915 185, DE-A-3 612 194 or DE-A-2 602 234.

Although they have already rendered great services, known jet pump-based suction devices do not do not always give satisfaction.

In particular, it was found that the flow injected into the jet pump, corresponding to a return of fuel from the engine, or to a fuel bypass taken from the pump outlet, sometimes has pressure and / or pressure fluctuations large flows so it is difficult to adapt the characteristics of the jet pump, and in particular avoid the appearance of significant back pressures, by jet pump inlet, if the jet section of outlet is too narrow for flow and / or pressure injected.

Various proposals have been made for try to eliminate this drawback.

So, for example, we proposed in the document DE-A-4 201 037 to arrange inside the nozzle, in upstream of the outlet nozzle thereof, a plunger core carried by a spring-loaded membrane, so that the plunger retreats in the event of an increase in pressure to increase the free section of the nozzle of the nozzle. According to a variant, document DE-A-4 201 037 proposes to make the very body of the nozzle in the form of a deformable element with respect to a plunger core fixed again to adapt the outlet section of the nozzle at the injected pressure.

The Applicant has itself proposed in its French patent application N ° 96 11739 filed on 26 September 1996 a jet pump in which the nozzle which receives the injected flow is formed by a compound nozzle of several lips of elastic material adapted from so that the nozzle has a variable section depending on the pressure and flow injected.

Document DE-U-9101313 describes a jet pump for transferring fuel to a fuel tank motor vehicle fuel comprising a cap of conical shape mounted with displacement opposite the main nozzle outlet nozzle and downstream of it.

Other known solutions consist in having, upstream of the nozzle or of the flow input injected from the jet pump, a relief valve capable of open when the injected pressure exceeds a threshold of valve calibration. However, these solutions the inconvenience of losing part of the fluid, in drift by the valve, so that this part of fluid is not not injected into the nozzle.

The present invention now aims to offer a new and improved jet pump.

This goal is achieved in the context of this invention by means of a jet pump of the type defined in claim 1 appended.

According to an alternative embodiment in accordance with the present invention, the core is provided with a channel longitudinal through forming an auxiliary nozzle. The operation of this alternative embodiment will described later.

• la figure 1 représente une vue schématique en coupe longitudinale d'une pompe à jet conforme à un mode de réalisation de la présente invention,
• les figures 2 et 3 représentent des vues schématiques en coupe transversale de la même pompe selon des plans de coupe référencés II et III sur la figure 1,
• la figure 4 représente une vue de la même pompe en position ouverte du gicleur,
• la figure 5 représente une vue en coupe longitudinale d'une pompe conforme à une variante de réalisation de la présente invention, en position fermée,
• les figures 6 à 9 représentent quatre variantes de réalisation d'une extrémité de gicleur conforme à la présente invention,
• la figure 10 représente une vue schématique en coupe longitudinale d'une pompe à jet conforme à une variante de réalisation de la présente invention,
• les figures 11 et 12 représentent la même variante pour deux débits différents injectés dans la pompe, et
• les figures 13 et 14 représentent des vues en coupe longitudinale de deux autres variantes de réalisation conformes à la présente invention.

Other characteristics, aims and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawings, given by way of nonlimiting examples and in which:

• FIG. 1 represents a schematic view in longitudinal section of a jet pump according to an embodiment of the present invention,
• FIGS. 2 and 3 represent schematic cross-sectional views of the same pump according to cutting planes referenced II and III in FIG. 1,
• FIG. 4 represents a view of the same pump in the open position of the nozzle,
• FIG. 5 represents a view in longitudinal section of a pump according to an alternative embodiment of the present invention, in the closed position,
• FIGS. 6 to 9 show four alternative embodiments of a nozzle end according to the present invention,
• FIG. 10 represents a schematic view in longitudinal section of a jet pump according to an alternative embodiment of the present invention,
• FIGS. 11 and 12 show the same variant for two different flow rates injected into the pump, and
• Figures 13 and 14 show views in longitudinal section of two other alternative embodiments according to the present invention.

We can see in Figure 1 attached a pump to jet according to the present invention comprising a cylinder housing 10 centered on a longitudinal axis O-O.

This box 10 defines a control input 12 receiving the injected flow, at a first end axial.

The axial output 14 of the pump is defined at the opposite axial end.

The housing 10 also has an input suction aid 16 which communicates laterally with the internal channel 18 of the housing 10.

This auxiliary suction input 16 is located near the control input 12. It can be formed by tubing inclined with respect to the axis O-O of the case, for example from an angle included between 10 ° and 90 °.

The housing 10 has at the entrance 12 a sprinkler 20. Thereafter this sprinkler 20 will be called "main" nozzle. It can be a sprinkler reported on input 12 as illustrated in FIG. 1, or a sprinkler integrated by manufacturing into the housing 10 or a section of the housing 10. Of course, a sealing must be defined between the inlet of the nozzle 20 and the input 12 of the housing 10.

More precisely still, according to the mode of preferred embodiment illustrated in the figures annexed, the nozzle 20 is composed of two sections 22, 24 axially juxtaposed.

The first section 22 in the flow direction is preferably of frustoconical convergent shape. The half angle at the top of this section 22 is preferably between 10 ° and 80 °.

The second section 24 of the nozzle 20 is cylindrical preference of revolution and cross-section constant. The free outer end 240 of this section 24 is preferably slightly rounded. We will describe by the following with regard to FIGS. 6 to 9 different modes of realization of such a nozzle end.

On the axial length of the nozzle 20, the section right of section 180 of channel 18 formed in the housing 10 is preferably cylindrical of revolution and constant dimension.

As previously stated, as part of the present invention, a core 30 is disposed opposite the nozzle outlet nozzle 20, being guided translation, along the O-O axis, against stress a spring 40.

The core 30 can be guided along the axis O-O by many appropriate means.

Preferably, the core 30 is provided with a channel central internal blind 32 opening at its end rear opposite the nozzle 20. Furthermore, the core 30 is engaged, by this channel 32, on a rod 50 centered in channel 18 and connected to housing 10. As an example not limiting, this rod 50 can thus be supported on the internal surface of the housing 10, in the channel of this one, by three fins 52 equi-distributed at 120 ° around the axis 0-0.

This rod 50 has most of its length a cylindrical section of constant dimension complementary to the cross section of channel 32 formed in the core 30. However, the rod 50 has preferably a tapered tapered rear section 54 or converge away from the nozzle 20.

The front face 56 of the rod 50 is preferably plane and orthogonal to the O-O axis. However, the face rear 58 of rod 50 is preferably rounded or conical.

The fins 52 are connected to the part cylindrical of the rod 50, immediately upstream of the transition zone towards the tapered section 54.

The core 30 has an envelope generally cylindrical outer of revolution and constant section.

The core 30 however has a front section frustoconical 34 terminated by a front end generally in hemisphere or in warhead 36. The nucleus 30 also has a tapered rear section 38.

The spring 40 is advantageously a spring of helical compression arranged in the channel 32 of the core 30 between the front face 56 of the rod 50 and the bottom of the channel 32.

Thus those skilled in the art will readily understand that the spring 40 urges the core 30 to bear against the nozzle of the nozzle 20, more precisely against the rear surface 240 of section 24 or on a generator contact.

The core 30 thus preferably rests against the free end 240 of the section 24, in the form of a zone limited substantially to a circular edge or on a contact generator defined at the zone level transition between the tapered section 34 divergent and the front end in hemisphere 36.

Downstream from the initial straight section 180 constant whose length coincides with the length of the nozzle 20, the channel 18 formed in the housing 10 can have a section 181 converging towards exit 14, itself followed by a straight section 182 constant cylindrical.

The length of the converging section 181 is advantageously equal to the length of the divergent section 34 of the core 30.

Finally, as seen on examining Figures 1 and 3, the core 30 is advantageously guided along the axis O-O, at its cylindrical section of revolution, by guide studs 17, for example three guiding studs evenly distributed at 120 °. These are from preferably arranged in the extension of the fins 52.

It is important to note that as part of the present invention the contact area defined between the front end of the core 30 and the outlet nozzle of the nozzle 20 has a limited amplitude.

We illustrated in Figure 6 a first variant of the end 240 of the nozzle 20. According to this first variant, the internal surface 202 and the external surface 204 of the section 24 of the nozzle 20 are cylindrical of revolution around the axis O-O, and the end 240 of the nozzle 20 is formed of a cap 208 O-ring, i.e. delimited in cross section by a circular sector, which connects tangentially on the external surface 204 and which joins the surface internal 202 at a circular edge 206, which edge 206 defines the contact at rest with the core 30. The angle defined between the toric cap 208 and the internal surface 202, at the connection between these can be the subject of various variants. he is typically of the order of 90 °.

The second embodiment of the end 240 of nozzle 20 illustrated in FIG. 7 is distinguished from that illustrated in FIG. 6 and previously described, by the fact that the toric cap 208 does not connect on the internal surface 202 in the form of an edge 206 circular, but connects tangentially to a second O-ring surface 210, radially internal, which itself connects tangentially to the surface internal 202. The contact at rest between the core 30 and the nozzle 20 is thus defined at this surface toric 210. The second toric surface 210, radially internal, has a radius of curvature less than that of the O-ring surface 208 radially external. In a way typical, but not limiting, the radius of the surface radially external toroidal 208 is of the order of 1 to 2 mm, while the radius of the toric surface 210 radially internal is of the order of 0.05 to 0.5 mm.

A third is illustrated in FIG. 8 variant according to which a flat surface in crown 212, or if necessary of frustoconical shape, is interposed between the two toric surfaces 208 and 212.

Finally we illustrated in Figure 9 a fourth variant which differs from that illustrated in Figure 8 by the fact that the surface O-ring 208 radially external is replaced by a chamfer or frustoconical surface 214.

Of course the end 240 of the nozzle 20 can be the subject of many other variations of production.

So we can consider connecting directly the chamfer 214 on the radially toroidal surface internal 210. Or you can replace the surface toric 208 by an annular surface whose generator in cross section has a radius gradually growing outward.

The jet pump architecture conforms to the present invention avoids any valve of discharge upstream of the nozzle 20. Thus, the present invention avoids any loss of return flow, in the form external discharge, so that the injected flow Qi is permanently equal to the return flow.

For the lowest injected flows, the section ejection, i.e. the free section of the nozzle 20 is reduced and increases the transmitted power to the jet pump by a high injection pressure Pi.

For high return flows, the core 30 recedes by compression of the spring 40, with respect to the nozzle 20 which increases the section of passage at the outlet of the nozzle and to limit the back pressure upstream of the nozzle 20 at an acceptable level.

The use of a translating Venturi 30 core downstream of the nozzle 20 thus makes it possible to guarantee a optimal jet pump efficiency for the weakest injected flow rates Qi (by reducing the nozzle diameter 20 and increased injection speed).

The flow of the flow leaving the nozzle 20 takes the form of a conical film channeled by the converge on the annular mixer.

By way of nonlimiting example, the angle of taper of the section 34 of the core is of the order of 8 °, of the section 38 of the core is of the order of 9 °, of section 181 of channel 18 is of the order of 5 ° and of section 54 of the rod 50 is of the order of 6 °.

Is illustrated in Figure 5 attached a variant which will not be described in the details, and which differs essentially from the mode of realization previously described by the fact that the element of core 30 biased by spring 40 opposite the nozzle outlet nozzle 20, and downstream thereof, is guided in translation along the axis O-O, by the rod 50 linked to the housing 10, not outside of this rod, but inside it, more precisely in a channel blind 51 which opens onto the front surface of this rod 50.

We will now describe the variant of embodiment illustrated in Figures 10 to 12 attached.

This variant is essentially distinguished from those previously described, by the fact that according to Figures 10 to 12, the core 30 is provided with a channel longitudinal through 300. This forms a nozzle auxiliary whose operation will be described by the after.

The geometry of this channel 300 can be the subject of various variants.

According to the embodiment illustrated in the Figures 10 to 12, the channel 300 is formed of three sections successive, 302, 304, 306, which follow one another from nozzle 20, towards the pump outlet.

The first section 302 is cylindrical with revolution and constant section. He's stretching typically over 4/5 of the length of the core 30.

The second section 304 is converging in the direction from the pump outlet.

The third section 306 is cylindrical revolution and at least substantially constant section.

Typically the outlet diameter of the channel 300, or the outlet diameter of section 306 (which auxiliary nozzle) is between 0.4 and 1mm.

As previously described for the modes of embodiment illustrated in Figures 1 to 9, the core 30 is guided in translation opposite the nozzle outlet 20 and biased towards this outlet by a spring 40.

The core 30 can be guided in translation by all appropriate means. According to the embodiment no limitative illustrated in FIGS. 10 to 12, provision is made for this purpose on the internal surface of the housing 10, longitudinal fins 310, for example three fins 310 distributed at 120 °, which in combination define a additional free internal volume of the envelope of the core 30. As a variant, the fins 310 secured to the core 30.

Of course according to this variant it is important to use guide means which do not disturb the operation of the auxiliary nozzle 300 nor the flow likely to flow between the outlet of the nozzle 20 and the outer surface of the core 30, and by therefore who do not get these.

The spring 40 can take various configurations.

According to the embodiment illustrated in the Figures 10 to 12, it is formed of a spiral spring which is supported on the one hand on a recess of the core 30, on the other hand on the upstream end of fins 110 integral with the internal wall of the housing 10, for example three fins 110 distributed at 120 °.

The arrangements illustrated in FIGS. 10 to 12 increase suction performance of the very low flow annular jet pump injected (typically for flow rates below 20 l / h) while limiting the back pressure (or injection pressure) to maximum return flow.

When the flow in inlet 12 is zero, it the same is true for the flow in the suction inlet 16, and for the flow at outlet 14 (see Figure 10). In this in this case, the core 30 rests on the end of the nozzle 20.

When the flow Qi injected into inlet 12 is low, the back pressure Pi remains below the threshold of opening pressure Ps of the core 30 (function of the calibration compression spring 40), which locates injection through the auxiliary nozzle formed by the longitudinal channel 300 of the core 30 (see Figure 11). The Venturi effect is then achieved in a conventional manner and the transferred flow is collected through the tube mixer located downstream of the core 30.

When the flow Qi injected into input 12 increases, the back pressure goes above the threshold pressure Ps and the nucleus 30 gradually recedes by deformation of the spring 40, freeing a section of annular passage between the core 30 and the nozzle 20, as described above with reference to Figures 1 to 9. This discharge limits the increase in pressure above, of Ps for the high flow rates injected Qi, while ensuring a secondary Venturi effect by sprinkler outlet 300, which contributes to the increase of the flow Qa sucked through the inlet 16, after the core 30 (see figure 12). It should be noted in particular that a single flow annular jet pump can be obtained, according to the architecture illustrated in FIGS. 10 to 12, in obstructing the channel 300 formed in the core 30.

There is thus illustrated in FIG. 14, a variant with double flow in which the core 30 provided with a longitudinal through channel 300, rests on the outlet of the nozzle 20 via a bearing surface of hemispherical or semi-toroidal geometry (while the bearing surface of the core 30 is generally frustoconical according to Figures 10 to 12); and in FIG. 13, an alternative embodiment which is not distinguishes from figure 14 that by the fact that the channel 300 is obstructed. So the embodiment of the figure 13 corresponds to a simple flow. In both cases Figures 13 and 14, the core 30 is guided by fins 310 as described with reference to FIGS. 10 to 12; and the spring 40 is supported between the core 30 and fins 110 integral with the housing 10.

Claims (20)

1. A jet pump, in particular for transferring fuel in a motor vehicle fuel tank, the pump comprising a main nozzle (20) and a core (30) mounted to move relative to the outlet bore of the main nozzle (20) and downstream therefrom, the pump being characterized by the facts that, at rest, said core is formed of a core (30) in contact with the outlet bore of the main nozzle (20), and that the core (30) is of right section that increases going away from the outlet bore of the main nozzle (20).
2. A pump according to claim 1, characterized by the fact that the core (30) is provided with a through longitudinal channel (300) forming an auxiliary nozzle (306).
3. A pump according to claim 2, characterized by the fact that the outlet diameter of the through channel (300) lies in the range 0.4 mm to 1 mm.
4. A pump according to any one of claims 1 to 3, characterized by the fact that the main nozzle (20) possesses a converging segment (22) followed by a segment of constant section (24).
5. A pump according to any one of claims 1 to 4, characterized by the fact that the half-angle at the apex of the main nozzle (20) lies in the range 10° to 80°.
6. A pump according to any one of claims 1 to 5, characterized by the fact that the end of the outlet bore of the main nozzle (20) is generally rounded in shape.
7. A pump according to any one of claims 1 to 6, characterized by the fact that the core (30) possesses a generally frustoconical front segment (34) terminated by a front end (36) that is generally hemispherical or bullet-shaped.
8. A pump according to claim 7, characterized by the fact that the cone angle of the front segment of the core (30) is about 8°.
9. A pump according to any one of claims 1 to 8, characterized by the fact that the core (30) possesses a generally cylindrical envelope of constant section.
10. A pump according to any one of claims 1 to 9, characterized by the fact that the core (30) possesses a rear segment (38) that converges going away from the main nozzle (20).
11. A pump according to any one of claims 1 to 10, characterized by the fact that it includes a spring (40) interposed between the front end of a support (50) and the core (30).
12. A pump according to any one of claims 1 to 11, characterized by the fact that the core is guided by support means associated with the inner wall of the housing (10) by radial fins (52).
13. A pump according to any one of claims 1 to 12, characterized by the fact that the housing (10) of the pump defines an internal channel possessing a segment (181) that converges in the flow direction, and that is located in register with the diverging segment of the core (30).
14. A pump according to claim 13, characterized by the fact that the length of the converging segment of the channel (18) formed inside the housing (10) is of the same order of magnitude as the length of the diverging segment (34) formed on the core (30).
15. A pump according to any one of claims 1 to 14, characterized by the fact that the core (30) is guided inside the channel (18) of the housing (10) by radial splines (17) associated with the inner surface of the channel (18).
16. A pump according to any one of claims 1 to 15, characterized by the fact that the contact defined between the core (30) and the outlet bore (24) of the main nozzle (20) is formed by a circular edge (206).
17. A pump according to any one of claims 1 to 15, characterized by the fact that the contact defined between the core (30) and the outlet bore (24) of the main nozzle (20) is formed via a generally toroidal cap (210) of said outlet bore.
18. A pump according to claim 17, characterized by the fact that the radius of said generally toroidal cap (210) lies in the range 0.05 mm to 0.5 mm.
19. A pump according to claim 2, characterized by the fact that the longitudinal channel (300) in the core (30) has a converging segment (304).
20. A fuel tank fitted with a jet pump in accordance with any one of claims 1 to 19.

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