Suction Jet Pump

Abstract

The invention relates to a suction jet pump (12), composed of a housing (18) having a connection (24), a propellant line (14), a propulsion jet nozzle (19), a mixing tube (15) which adjoins said propulsion jet nozzle (19), and a suction point (13) arranged upstream of the mixing tube (15). In addition, the suction jet pump (12) has a second suction point (16).

Description

The invention relates to an eductor-jet pump, comprising a housing having a connection of a motive fluid line, an eductor jet nozzle, an adjoining mixing tube and a suction point located upstream of the mixing tube. Such eductor-jet pumps are used in fuel tanks of motor vehicle, in order to deliver fuel from different areas of the fuel tank to a fuel pump located in the fuel tank.

Eductor-jet pumps of the aforementioned type are used in multiple-chamber tank systems, in which the fuel tank has at least two chambers, so as to be able to drain all chambers as efficiently as possible, especially in the event of a low filling level in the fuel tank. A distinction is made between two types of eductor-jet pump. The first type draws in fuel more or less directly through a suction point. For this purpose the eductor-jet pump is located at the point from which the fuel is pumped. The second type of eductor-jet pumps are suction eductor-jet pumps, the suction point of which is connected to a suction line. The suction line is carried into the area from which the fuel is to be pumped. Apart from the somewhat higher costs of generating a sufficient vacuum for the suction line, this type of eductor-jet pump has the advantage of being independent of the site from which fuel is to be pumped. A disadvantage of both types of eductor-jet pump is that the number of eductor-jet pumps needed is equal to the number of chambers to be drained. Despite their relatively simple construction, the cost of parts and assembly is considerable.

The object of the invention is to reduce the cost of draining a fuel tank having multiple chambers or areas to be drained.

According to the invention the object is achieved in that the eductor-jet pump has a second suction point.

Providing a second suction point creates an eductor-jet pump with passive secondary suction, which does not need an additional drive in the form of a further motive jet. In this way it is possible to halve the number of eductor-jet pumps required for a multiple-chamber fuel tank. This leads, in particular to a considerably reduced assembly cost. The efficiency of the overall fuel delivery system is furthermore improved, since obviating the need for a motive jet for the second suction point means that the fuel pump needs to provide less hydraulic power for driving the eductor-jet pump. The hydraulic power saved can either be delivered to the internal combustion engine of the motor vehicle as additional fuel delivery, or the fuel pump can be of smaller dimensions. The eductor-jet pump with passive secondary suction is particularly effective in the case of small fuel delivery quantities.

The second suction point is especially easy to configure if the suction point opens into the mixing tube of the eductor-jet pump.

The design arrangement of the second suction point on the eductor-jet pump, particularly on the mixing tube, is relatively easy to configure if it has a smaller cross section than the first suction point. Assuming a first suction point cross section in the order of 100 mm²-200 mm², the second suction point may be up to 100 times smaller in cross section.

A suction line can be fitted to the second suction point with little effort if the second suction point opens into a diffuser of the mixing tube, the diffuser being arranged on the side of the mixing tube remote from the eductor jet nozzle.

With a diffuser of small axial length the arrangement of the second suction point can sometimes prove difficult. It has therefore proved advantageous to have the second suction point opening out in a section, preferably a cylindrical section, of the mixing tube situated upstream of the diffuser. This section has a sufficient axial length, which allows the second suction point to be located without any problems.

In another embodiment the second suction point is arranged in the area of the first suction point relative to the axial extent of the eductor-jet pump, preferably in the housing of the eductor-jet pump. In this embodiment the mixing tube remains unaltered, making it possible to use existing forms of mixing tube. Another advantage is that eductor-jet pumps, which are fitted via the mixing tube, by inserting it together with the mixing tube, for example, into a swirl pot, can be fitted without modification. The second suction point therefore has no effect on the fitting of the eductor-jet pump.

The second suction point is located on the periphery of the eductor-jet pump at an angle of 20° to 180°, preferably between 90° and 180°, to the first suction point. By purposely selecting the angle, the eductor-jet pump can thereby be readily adapted to the given installation geometry.

Large angles in the order of 180° between the two suction points have proved advantageous when the first suction point is oriented vertically downwards in the installation position of the eductor-jet pump, and the scope for installation in a horizontal direction is limited. The suction line of the second suction point in this case leads basically perpendicularly to the eductor-jet pump. A large angle is furthermore advantageous when the eductor-jet pump is arranged between two areas from which fuel is to be drawn. The two suction points are then oriented substantially horizontally. Unnecessary deviations of the suction lines are therefore avoided.

A small angle is advantageous when the areas from which the eductor-jet pump is to draw fuel lie in one direction relative to the eductor-jet pump, or both suction lines have to be laid in one direction owing to the space available in the fuel tank.

In an eductor-jet pump manufactured by injection molding, a good mold release and hence simply designed dies are achieved if the second suction point is arranged with its axial extent perpendicular to the axial extent of the eductor-jet pump.

A reduction in the overall radial extent is achieved in another development with an eductor-jet pump in which the second suction point is arranged with its axial extent at an angle to the axial extent of the eductor-jet pump that deviates from the perpendicular.

The second suction point can be produced especially cost-effectively if it is integrally formed with the eductor-jet pump. A housing or an eductor-jet pump formed in this way is particularly cost-effective to manufacture owing to the good mold release facility, especially where the second suction point is arranged at an angle of 180° to the first suction point.

In one simple development the second suction point is embodied as a connection, to which a line in the form of a suction line can be connected.

In another development the second suction point is embodied as a bore, into which a line in the form of a suction line can be inserted.

The connection of the motive fluid line is arranged radially or axially in relation to the axial extent of the eductor-jet pump, according to the installation conditions. In the case of eductor-jet pumps having a radial connection of the motive fluid line, an embodiment of the eductor-jet pump in which the second suction point has the same radial orientation as the connection has proved advantageous. For one thing, such an eductor-jet pump takes up little overall space in a radial direction. For another, such an eductor-jet pump can be cost-effectively manufactured by injection molding, the dies being of especially simple design, due to the fact that the connection and the second suction point both have the same radial orientation and the demolding direction associated therewith is shared.

According to a further development a wider scope for adapting the eductor-jet pump according to the invention to various installation conditions is achieved by means of a separate diffuser, which is designed for connection to the mixing tube. The radial position of the second suction point is fixed and therefore adapted to the actual installation situation according to the radial orientation of the diffuser in the assembly with the remainder of the mixing tube. Such an eductor-jet pump is therefore versatile in use. The connection of the diffuser to the remainder of the mixing tube is especially easy to make as a snap socket connection. It is also feasible, however, to connect the diffuser to the remainder of the mixing tube by means of a welded or adhesively bonded connection.

The invention will be explained in more detail with reference to several exemplary embodiments. In the drawing:

FIG. 1 shows the arrangement of an eductor-jet pump in a fuel tank,

FIG. 2 shows a section through an eductor-jet pump according to the invention and

FIGS. 3-6 show further embodiments of the eductor-jet pump according to FIG. 2.

The fuel tank 1 represented in FIG. 1 comprises two chambers 2, 3, which are connected together via a saddle 4. A fuel supply unit 5, which is fitted into the fuel tank 1 via an opening 7 closed by a flange 6, is arranged in the chamber 2. The fuel supply unit 5 comprises a swirl pot 8, in which a fuel pump 9 is arranged. Fuel drawn out of the swirl pot 8 by the fuel pump 9 via a pump pre-filter 10 is delivered via a feed line 11 though the flange 6 to an internal combustion engine (not shown).

For filling the swirl pot 8, an eductor-jet pump 12, which draws fuel from the fuel tank 1 via a first suction point 13 and delivers it into the swirl pot 1, is arranged in the base area of the swirl pot. The eductor-jet pump 12 is driven by a motive fluid line 14 with fuel delivered by the fuel pump 9. Whilst in the representation shown the motive fluid line 14 branches off from the feed line 11, it is also feasible to feed the motive fluid line 14 directly from the pump stage of the fuel pump 9.

In the area of the mixing tube 15 the eductor-jet pump 12 has a second suction point 16, which is connected to a suction line 17. The suction line 17 is carried into the base area of the chamber 3, so that in operation of the eductor-jet pump 12 fuel is delivered from the chamber 3 into the swirl pot 8.

FIG. 2 shows the eductor-jet pump 12 from FIG. 1. The eductor-jet pump 12 has a common housing 18, which links the various areas of the eductor-jet pump 12 together to form an integral structure. An eductor jet nozzle 19 with a nozzle opening 20, which is oriented axially to the mixing tube 15, is arranged in the housing 18. The mixing tube 15 comprises an inlet area 21, and a cylindrical section 22, adjoining which is a downstream diffuser 23. A first suction point 13 as primary suction is arranged upstream of the mixing tube 15 in the direction of flow. In the horizontal installation position of the eductor-jet pump 12 shown, the first suction point 13 is oriented vertically downwards.

The eductor jet nozzle 19 is integrally connected to a connection branch 24, which at its end remote from the eductor jet nozzle 19 is provided with a pine-tree profile for connection of the motive fluid line 14 (not shown). The connection branch 24 is arranged on the periphery of the eductor-jet pump 12 perpendicular to the axial extent of the eductor-jet pump 12 and at an angle of 180° to the first suction point 13. An opening in the eductor jet nozzle 19, made opposite the nozzle opening 20 for production reasons, is closed by means of an impressed ball 25.

The cylindrical section 22 has a connection 26, which in a similar way to the branch connection 24 is arranged on the periphery of the eductor-jet pump 12 perpendicular to the axial extent of the eductor-jet pump 12 and at an angle of 180° to the first suction point 13. Connected to the connection 26 is the suction line 17 (not shown), the connection 26 forming the second suction point 16. For arranging the suction line 17 on the connection 26, the latter may be designed with a pine-tree profile like the branch connection 24.

When fuel is delivered to the eductor-jet pump 12 via the motive fluid line it emerges via the nozzle opening 20 and enters the mixing tube 15. In so doing the fuel emerging from the nozzle opening 20 generates a negative pressure in the area of the first suction point 13, with the result that fuel is drawn out of the fuel tank by this primary suction at the first suction point 13 and is delivered via the mixing tube 15 into the swirl pot. Delivering the fuel through the mixing tube 15 likewise generates a negative pressure in the connection 26 of the second suction point 16, with the result that fuel is drawn out of the other chamber of the fuel tank via the suction line and delivered into the swirl pot.

In construction, the eductor-jet pump 12 in FIG. 3 differs from the eductor-jet pump in FIG. 2 in that the connection branch 24 is arranged coaxially with the horizontal extent of the eductor-jet pump 12. In the housing 18 the connection 26 of the second suction point 16 is arranged in the area of the first suction point 13, relative to the axial extent. The connection 26 is in turn arranged on the periphery of the eductor-jet pump 12 perpendicular to the axial extent of the eductor-jet pump 12 and at an angle of 180° to the first suction point 13.

FIG. 4 shows a sectional top view of an eductor-jet pump 12, the basic construction corresponding substantially to the eductor-jet pump according to FIG. 3. The eductor-jet pump 12 has a horizontal connection branch 24, which merges into the housing 18. The first suction point 13 is again situated on the underside of the eductor-jet pump 12, so that it is hidden by the eductor jet nozzle 19. In contrast to FIG. 3, the connection 26 of the second suction point 16 is arranged on the periphery of the eductor-jet pump 12 at an angle of 90° to the first suction point 13 and therefore in the plane of projection. The eductor-jet pump 12 thereby has an especially low overall height in a vertical direction. The connection 26 is arranged at an angle deviating from the perpendicular in relation to the axial extent of the eductor-jet pump 12, the angle a between the axial extent of the eductor-jet pump 12 and the axial extent of the connection 26 being 55°.

FIG. 5 shows an eductor-jet pump 12 having a basic construction according to FIG. 3. The second suction point 16 is arranged in the area of the diffuser 23 and takes the form of a bore 27, in which the suction line (not shown) is fixed by insertion.

The eductor-jet pump 12 in FIG. 6 shows a further embodiment of the eductor-jet pump according to FIG. 5. The diffuser 23 has a connection 26 as second suction point 16, the diffuser 23 being designed as a separate component. On its side facing the mixing tube 15 the diffuser 23 has a radial circumferential groove on its inside diameter. This interacts with a bead 28 running radially around the outside diameter of the mixing tube 15. The clip connection thus formed allows the diffuser 23 to be fixed to the mixing tube 15. The radially circumferential design of the groove and the bead 28 allows the connection 26 to be oriented radially at any angle perpendicular to the axial extent of the eductor-jet pump 12.

Claims

1.-13. (canceled)

14. An suction jet pump, comprising:

a housing, having a connection to a motive fluid line, an ejector nozzle, a mixing tube adjoining the ejector nozzle, a first suction point located upstream of the mixing tube for receiving fluid to pumped, and a second suction point for receiving fluid to be pumped.

15. The suction jet pump of claim 14, wherein the second suction point opens into the mixing tube.

16. The suction jet pump of claim 15, further comprising a diffuser on a side of the mixing tube remote from the ejector nozzle, the second suction point opening into the diffuser of the mixing tube.

17. The suction jet pump of claim 14, further comprising a diffuser on a side of the mixing tube remote from the ejector nozzle, wherein the second suction point opens into a section of the mixing tube situated upstream of the diffuser.

18. The suction jet pump of claim 14, wherein the second suction point is arranged in the area of the first suction point relative to the axial extent of the suction jet pump.

19. The suction jet pump of claim 14, wherein the second suction point is located at a location on a periphery of the suction jet pump separated by an angle of 20° to 180° from a location of the first suction point about a longitudinal axis of the suction jet pump.

20. The suction jet pump of claim 19, wherein the angle is between 90° and 180°.

21. The suction jet pump of claim 14, wherein a longitudinal axis of the second suction point is perpendicular to a longitudinal axis of the mixing tube.

22. The suction jet pump of claim 14, wherein a longitudinal axis of the second suction point is arranged at an angle to a longitudinal axis of the mixing tube that is non-perpendicular.

23. The suction jet pump of claim 14, wherein the second suction point is integrally formed with the suction jet pump as only one single piece.

24. The suction jet pump of claim 23, wherein the second suction point is embodied as a connection to which a line for conducting fluid is connectable.

25. The suction jet pump of claim 14 wherein the second suction point is embodied as a bore, into which a line for conducting fluid is insertable.

26. The suction jet pump of claim 14, wherein the connection of the motive fluid line is arranged in a radial orientation relative to a longitudinal axis of the suction jet pump and the second suction point has the same radial orientation as the connection.

27. The suction jet pump of claim 16, wherein the diffuser is a separate component configured to connect to the mixing tube.

28. The suction pump of claim 27, wherein the diffuser is connectable to the mixing tube by a snap-socket connection.