WO1989007712A1

WO1989007712A1 - Auxiliary fuel-feed device

Info

Publication number: WO1989007712A1
Application number: PCT/BR1988/000002
Authority: WO
Inventors: Carlos Fernando Damasceno; Hideki Iwamoto
Original assignee: Volkswagen Do Brasil S.A.
Priority date: 1988-02-11
Filing date: 1988-02-11
Publication date: 1989-08-24
Also published as: CN1035162A; ES2007160A6; ZA881570B

Abstract

An auxiliary fuel-feed device to be installed in the fuel-feed circuit of internal-combustion engine equipped with return tubing (19) for excess feed fuel, which provides a means (21) that allows an additional amount of fuel to be added to the return-fuel flow that is sufficient to ensure that, per unit time, the sum of the volume of return fuel and the volume of additional fuel, deposited in the tank (10) pertaining to the fuel-feed auxiliary device, will be greater than the volume of the fuel removed from the auxiliary tank (10) by the feed tubing (16), thus being ensured that, while the internal-combustion engine is running, the tank pertaining to the fuel-feed auxiliary device is continuously supplied and its maximum level maintained, with no need to resort to auxiliary pumping measures for such purposes.

Description

TITLE: "AUXILIARY FUEL-FEED DEVICE"

The object of this invention is a device installed in the fuel-feed circuit of internal-combustion engines, in particular feed circuits equipped with return tubing for excess feed fuel, such device being intended to ensure that there will be no interruption in the flow of feed fuel while the internal-combustion engine is operating, even under adverse conditions.

In certain circumstances, for example, when the vol- ume of fuel contained in the fuel tank of an automotive vehi¬ cle falls below a certain minimum level and this vehicle travels through a prolonged curve, uphill or downhill, or if it is otherwise subjected to sudden and pronounced changes in speed, direction, etc., the fuel could be displaced to one side of the tank to such an extent that the inlet end of the dip tube, which forms part of the fuel-intake tubing, is at least temporarily no longer submerged in the fuel. Under such conditions, the dip tube sucks out air instead of fuel, there¬ by producing an interruption in the feed fuel flow that im- pedes the proper operation of the internal-combustion engine. There have been a number of attempts to solve this problem, with varying degrees of success and cost. As an example of such attempts, mention can be made of those that envisage fuel tanks equipped with: - special shapes, e.g., with their bottom in the shape of an inverted cone or truncated cone;

- a labyrinth of plates that prevents fuel from moving about freely within the tank;

- flexible dip tubes that change position in keeping with the momentary movement of fuel in the fuel tank; auxiliary pumping means that feed supplementary tanks located within the fuel tank.

With a view to an effective and at the same time in- expensive solution to the problem, the present auxiliary fuel- feed device has been developed. This device, installed within the fuel-feed circuit equipped with return tubing for excess feed fuel, for example found in certain feed circuits in Otto cycle engines as well as in Diesel cycle engines, allows the flow of returning fuel to be increased by an additional amount of fuel that is sufficiently large to ensure that, per unit of time, the sum of the volume of returning fuel and the volume of additional fuel deposited in the auxiliary tank pertaining to the auxiliary fuel-feed device will be greater than the volume of fuel removed from this tank during the same period of time by the feed tubing, without the need to resort to aux¬ iliary pumping means for such purposes.

The device of this invention typically consists of:

- an auxiliary tank that can be placed inside and close to the bottom of the fuel tank, its lower region being provided with a one-way valve that allows fuel to flo into the aux¬ iliary tank, and its upper area, at its level of maximum capacity, being provided with an outlet for air and any fuel that exceeds the maximum capacity of the auxiliary tank; - a dip tube, with one end connectable to the feed tubing and the other end located close to the auxiliary tank bottom;

- a return tube, with one end connectable to the jEturn tubing and the other end located inside the auxiliary tank, the inventionconsisting of the fact that the device comprises a suction tube having one end open to the exterior of said auxiliary tank in the region of the bottom thereof, while its other end is in communication with the interior of said return tube so that, when the fuel flow passes through this return tube, a pressure differential is created between the return tube and the suction tube, generating enough suction to suck fuel up through the said end of the suction tube that is open to the exterior of the auxiliary tank.

By using the auxiliary fuel-feed device while the internal-cαnbustion engine is running, an auxiliary tank in¬ side the fuel tank itself can be supplied and its maximum capacity maintained. Therefore, except when there is no fuel whatsoever, this assures that the intake end of the extraction tube will remain submerged in the fuel contained in the aux¬ iliary tank, even under adverse conditions, with the result being that there is no interruption in the flow of feed fuel. Based on the invention, use is made of a principle analogous to that by which auxiliary pumping means are en¬ visaged in order to supply a supplementary tank positioned in¬ side the automobile fuel tank, but without it being necessary to have mechanical devices and additional parts that, in the state of the art, represent increased complexity as well as naturally being subject to the failures inherent in such com¬ ponents. The present invention offers a solution whereby no moving parts or auxiliary motors are used to pump fuel, the device thus being much simpler and less likely to fail. The present invention will now be described in greater detail by way of example and with reference to the attached drawings, in which:

Fig. 1 is a schematic representation of a fuel- feed system using a device according to the present invention;

Fig. 2 is a partially cut-away front view of an auxiliary fuel-feed device in accordance with the invention; Fig. 3 is a front partially cut-away view of a first embodiment of the auxiliary fuel-feed device in accordance with the invention; Fig. 4 is a cross-section taken along line A-A of Fig. 2 showing a second embodiment of the present invention; Fig. 5 is a front partially cut-away view of a third embodiment of the auxiliary fuel-feed device according to the present invention; Fig. 6 is a partially cut-away view of a fourth embodiment of the auxiliary fuel-feed device according to the present invention; Fig. 7 is a cross-sectional view taken on line

B-B of Fig . 6; Fig. 8 is a front partially cut-away view of a fifth embodiment of the auxiliary fuel- feed device; Fig. 9 is an enlargement of detail C of Fig. 3; Fig. 9A is an alternative for the arrangement shown in Fig. 9;

Fig. 10 is an enlargement of detail D shown in

Fig. 4; Fig.lOA is an alternative for the arrangement shown in Fig. 10; Fig.11 is an enlargement of detail E shown in

Figures 5, 6 and 8, and Fig.12 is a cross-sectional view on line F-F of

Fig. 11. Referring now to the drawings, and in particular Figure 1, inside and near the bottom of a conventional fuel tank 1 there is an auxiliary feed device 2 connected on the one hand to the feed tubing 3 and on the other hand, to the return tubing 8 for the feed fuel of an internal-combustion engine. The feed tubing 3, which incorporates a fuel pump or a fuel-injection pump 4, as well as a fuel filter 5, leads to atomizer or injector nozzles 6, each corresponding to one of the cylinders of the internal-combustion engine and terminates in a pressure regulator 7 from which the re- turn tubing 8 returns only excess in the feed fuel admitted by the feed tubing 3.

An auxiliary feed device 2 in accordance with the invention comprises an auxiliary tank 10, consisting of tele- scopically coupled upper and lower parts 10' and 10". Enter- ing the auxiliary tank 10 is a two-part telescopic dip tube 16, 16' connected by a bellows-like sleeve 18 through which the feed fuel for the engine cylinders is sucked from the auxiliary tank , as well as a two-part telescopic return tube 19, 19' connected by a bellows-like sleeve 18, through which the excess feed fuel that is not consumed returns to the auxiliary tank 10.

In the embodiment illustrated by way of example, the auxiliary tank 10 is coupled to a conventional cover assembly with fuel gauge 9. By making the auxiliary tank 10, the dip tube 16, 16' and the return tube 19,19' telescopic, any dimensional tolerances are compensated.

Leading from this cover assembly 9 with its fuel gauge and into the auxiliary tank 10 are the dip tube 16,16' and the return tube 19,19', with the intake end of the dip tube 16,16' close to the bottom 11 of the auxiliary tank 10, while the discharge end 20 of the return tube 19,19' is at a point located close to the maximum capacity level of the auxiliary tank 10.

The lower part of the auxiliary tank 10 is equip¬ ped, preferably at its bottom 11, with a check valve 12 that allows fuel to pass from the fuel tank 1 into the auxiliary tank 10, but not in the opposite direction.

Also at the bottom and on the outside of the auxiliary tank 10, there is a screen 13 for retaining any impurities in the fuel, defining a space 14 between the out¬ er face of the bottom 11 and the screen 13, the impurities not_.being allowed to penetrate space 14. A spacer 15 with cutouts 15" ensures that fuel from the tank 1 will pass be¬ neath the lower face of the auxiliary tank 10.

As illustrated (Details C,D and E) , the upper end of a suction tube 21 penetrates and opens into the return tube 19 ' , while the lower end of the suction tube passes through the bottom 11 of the auxiliary tank 10 and enters the space 14 between the outer face of the bottom 11 and the catch screen 13. This suction tube connects the return tube 19, 19' directly to the fuel reserves inside the fuel tank 1, which enters through catch screen 13 into space 14.

As can be seen, particularly in figs. 9A, 10A and 11, depending on the αequirements for return-f el flow velocity and for performance preferences, the suction tube 21 may open into the return tube 19, 19' in a throttling area 19" pertaining to the return tube 19', or else the suction tube 21 may be equipped with an assembly 24 of hydro- dynamic shapes by means of which, as shown (Detail E) , it enters return tube 19' . This assembly 22 of hydrodynamic shapes consists of a substantially conical head 23, and is supported on the internal wall of return tube 19 * by means of its ribs 24, so that, owing to the difference between the internal diameter of the return tube 19' and the external dia¬ meter of the head 23, the formation of a circular gap 25 is ensured. Holes 28 communicating perpendicularly with the suction tube 21 open into neck 27 beneath head 23. An en¬ larged area 26, substantially in the shape of a truncated cone, is positioned with its base facing neck 27.

Dividing the auxiliary tank 10 into two compart- ments 29 and 30, a partition 31 with passage means 34 non- obstructively separates the compartment 30 into which the return tube 19, 19' projects, from the compartment 29 into which the extraction tube 16, 16' enters.

In one of the various possible embodiments (figs. 3, 4 and 8) , the partition 31, provided with passage means

34 in the form of an opening in its bottom, divides the auxi¬ liary tank 10, longitudinally into two compartments 29 and 30.

In another embodiment (fig.5), a collector bowl 32 provided with passage means 35 in the form of holes arrang- ed around its rim, transversally divides the auxiliary tank 10 into two compartments 29 and 30.

In yet another embodiment (fig. 6) , the collector bowl 33, which transversally divides the auxiliary tank 10 into two compartments 29 and 30, is equipped with a semi- circular downwardly-sloping ramp 38, with the passage means 36 in the form of a semicircular gap located on a semicircu¬ lar upwardly-sloping ramp 37.

In the latter two embodiments (figs. 5 and 6), the dip tube 16, 16' and the suction tube 21 pass through the respective collector bowls 32 and 33.

An opening 39 in the upper area of the auxiliary tank 10 serves both as an air outlet, and as a fuel overflow for which the maximum capacity of auxiliary tank 10 is ex¬ ceeded. When the internal-combustion engine is not run¬ ning, the fuel level in the auxiliary tank 10, due to the check valve 12 that allows fuel to flow from the fuel tank 1 into the auxiliary tank 10, though not in the opposite direc- tion, will at least be the same as the fuel level in the fuel tank 1.

When the internal-combustion engine is started up, the fuel pump orinjection pump 4 will supply the fuel-feed system by sucking fuel through dip tube 16,16', whose intake end 17 is submerged in the fuel in auxiliary tank 10. The drop in the level of fuel in the auxiliary tank 10 caused by supplying the fuel-feed system is rapidly compensated by the passage of fuel proceeding from the fuel tank 1 into the auxi¬ liary tank 10 through check valve 12. Taking into account that the volume of fuel sup¬ plied to the feed system is greater than the volume of fuel required by the atomizer or injector nozzles 6 during opera¬ tion of the internal-combustion engine, the surplus fuel is returned by return tubing 8 and return tube 19, 19' to auxi- liary tank 10.

When this surplus fuel returns through the return tube 19, 19', it passes in front of the suction tube outlet mouth 21 in the return tube 19' as shown in Details C and D, creating a pressure drop in suction tube 21 with the result that a certain additional volume of fuel coming from the fuel tank 1 and sucked up by suction tube 21 through the space 14 formed by catch screen 13 and the outer face of the bottom 11 of the auxiliary tank 10,is added to the volume of return fuel. If it is necessary to raise the pressure diffen- tial between the suction tube 21 and the return tube 19 ' , this return tube 19' will be equipped with a throat 19" as shown (figs. 9A and 10A) , whereby the desired effect will be obtained, and consequently, there will be an increase in additional fuel volume to be added to the return fuel volume.

In the embodiment utilizing the assembly 22 of hydrodynamic shapes (Details E) , the effect of the pressure differential between the suction tube 21 and the return tube 19 ' is obtained by the passing of return fuel through the circular gap 25 formed by the differences between the outer diameter of the head 23 of the suction tube 21 and the inner diameter of the return tube 19 ' . When the suction tube 21 and the return tube 19 ' or the head 23 of the suction tube 21 and the inner diameter of the return tube 19' are properly placed, shaped and di¬ mensioned, the volume of additional fuel, when added to the volume of return fuel, will cause the total volume of the return fuel and of the additional fuel, deposited per unit time in the auxiliary tank 10, to create a volume of fuel greater than that removed during the same period of time from the auxiliary tank 10 by the extraction tube 16,16" in order to supply the fuel-feed system so that, while the internal-combustion engine is running, the fuel level con¬ tained in the auxiliary tank 10 rises continually and is maintained at the maximum capacity level of the auxiliary tank 10, with all the fuel that exceeds the maximum capacity level of the auxiliary tank 10 overflowing through hole 39. The partitions 31, 32 and 33, whether of the type

31 that divides the auxiliary tank 10 longitudially and non- obstructively, or of the collector bowl type 32, 33 that divides the auxiliary tank 10 transversally and nonobstruc- tively into two compartments 30 and 29 into which the return tube 19, 19' empties and the extraction tube 16,16' passes fuel, respectively, are intended to allow the formation and elimination of possible air bubbles in the fuel emptied into the compartment 30 by the return tube 19, 19', before the fuel flows through the passage means 34, 35, 36 into the com- partment 29 of tank 10. In the embodiment shown in fig. 8, the elimination of air bubbles is further supplemented by filter means 40.

The embodiment with the collector bowl 33, equip¬ ped with a semicircular and downwardly-sloping ramp 38 as well as with an opening 36 in the form of a semicircular gap arranged on a semicircular upwardly-sloping ramp 37, is in¬ tended to impart a rotary movement to the fuel deposited in the collector bowl 33, thus avoiding the creation of turbu¬ lence that can lead to the formation of air bubbles. Although the embodiments described and illust¬ rated herein give preference to a system that allows for coupling of the auxiliary fuel-feed device 10 to a conven¬ tional fuel-gauge assembly 9, it should be understood that the subject matter of the present specification lends it¬ self to numerous structural modifications without, however, departing from the spirit of the invention, such as is defined in the following claims.

Claims

CLAIMS:

1. Auxiliary fuel-feed device for internal-combus¬ tion engines to be installed in a fuel-feed and return cir¬ cuit consisting of a fuel tank 1, feed tubing 3 and return tubing 8 for the excess feed fuel, such auxiliary device 2 comprised of:

- an auxiliary tank (10) that can be placed inside and close to the bottom of the fuel tank (1) , its lower region being provided with a one-way valve (12) that allows fuel to flow into the auxiliary tank (10) , and its upper area, at its level of maximum capacity, being provided with an outlet (39) for air and surplus fuel;

- a dip tube (16, 16') with one end connectable to the feed tubing (3) and the other end (17) located inside and close to the bottom (11) of the auxiliary tank (10) , and - a return tube (19, 19') with one end connectable to the return tubing (8) and the other end located inside the auxiliary tank (10) , characterized by a suction tube (21) having one end open to the exterior of said auxiliary tank (10) in the region of the bottom thereof, while its other end is in communication with the interior of said return tube (19') so that when the return fuel flow passes through the return tube (19, 19 *) , a pressure differential is created between the return tube (19, 19') and the suction tube (21), generating enough suction to suck fuel up through the said end of the suction tube that opens to the exterior of the auxiliary tank (10) .

2. A device in accordance with claim 1, charac¬ terized by the fact that the suction tube (21) opens up in¬ side the return tube (19') perpendicular thereto.

3. A device in accordance with claim 1, charac¬ terized by the fact that the suction tube (21) extends through the inside of the return tube (19 ') in the di¬ rection of fuel flow, opening up concentrically with the return tube (19') .

4. A device in accordance with claim 3, character¬ ized by the fact that the return tube (19') is essentially U-shaped, with the suction tube (21) entering the return AA

tube (19') through its curved area.

5. A device in accordance with claim 2 or 3, characterized by the fact that the return tube (19') is equipped with a throat (19") in the area where the suction tube (21) opens into the return tube (19').

6. A device in accordance with claim 1, character¬ ized by the fact that the suction tube (21) extends along the interior of the return tube (19') in a direction oppo¬ site to the fuel flow, within the return tube, at the end of the suction tube opening up inside the return tube being equipped with a head (23) thatproduces a reduction in the area of the inner cross-section of the return tube (19') .

7. A device in accordance with claim 6, character- ized by the fact that the head (23) has a substantially conical shape with its vertex pointing counter to the fuel flow in the return tube (19') .

8. A device in accordance with claim 7, character¬ ized by the fact that the substantially conical head (23) is provided with radially arranged ribs (24) that rest against the inside wall of the return tube (19').

9. A device, in accordance with any one of claims 6 to 8, characterized by the fact that the suction tube (21) is provided with an enlargement (26) in the shape of a truncated cone whose transverse section tapers off in the direction of the fuel flow in the return tube (19 ') , said enlargement (26) being separated from the head (23) by a neck (27) into which opens at least one hole (28) that communicates with the suction tube (21) , perpendicu- lar to the axis of such auction tube.

10. A device in accordance with claim 1, 2 or 6, characterized by the fact that the return tube (19') ex¬ tends through the inside of the auxiliary tank (10) up to a point located close to the maximum capacity level of the auxiliary tank (10).

11. A device in accordance with claim 1, charac¬ terized by a partition (31, 32 or 33) provided with a passage (34, 35 or 36) that nonobstructively divides the A Z.

auxiliary tank (10) into two compartments (30 and 29) in¬ to which the return tube (19, 19') empties and the dip tube (16, 16') enters, respectively.

12. A device in accordance with claim 11, characterized by the fact that the partition (31) divides the auxiliary tank (10) longitudinally into two compart¬ ments (29 and 30) .

13. A device in accordance with claim 11, char¬ acterized by the fact that the partition comprises a collector bowl (32 or 33) that divides the auxiliary tank (10) transversally into two compartments (29 and 30) .

14. A device in accordance with claim 13, char¬ acterized by the fact that the collector bowl (33) is equipped with a substantially semicircular downwardly sloping ramp and with an approximately semicircular passage (36) over an upwardly sloping substantially semi¬ circular ramp (37) .

15. A device in accordance with claim 1, char¬ acterized by the fact that next to the bottom of the aux- iliary tank (10) is provided a spacer (15) formed with cutouts (15^r) for the passage of fuel which, even when the spacer is seated on the bottom of the fuel tank (1) , per¬ mits fuel to pass through the space between the bottom of the auxiliary tank (10) and the bottom of the fuel tank (l) toward the one-way valve (12) provided in the bottom of the auxiliary tank (10) .