GB2180595A

GB2180595A - Fuel tank arrangement

Info

Publication number: GB2180595A
Application number: GB08622315A
Authority: GB
Inventors: Michiaki Sasaki
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 1985-09-18
Filing date: 1986-09-16
Publication date: 1987-04-01
Also published as: GB8622315D0; JPS6268131A

Abstract

A bottom wall of a fuel tank body defines an inwardly extending projection 32 which separates at least a lower segment of an interior of the fuel tank body into chambers 33 and 34. Fuel is pumped out of chamber 33. An ejector pump 40 is disposed within chamber 34. A communication pipe 47 connects the ejector pump 40 to chamber 33. A portion of the fuel pumped out of chamber 33 is returned to chamber 33 by way of the ejector pump 40 and the communication pipe 47. The ejector pump 40 is driven by the return fuel and transports fuel from chamber 34 to chamber 33 via the communication pipe 47. The ejector pump may take various constructional forms (Figs. 3 to 5). <IMAGE>

Description

SPECIFICATION Fuel tank arrangement This invention relates to a fuel tank arrangement, such as an automotive fuel tank arrangement.

Some automotive fuel tanks have bottom surfaces formed with recesses accommodating other automotive parts. These fuel tank designs enable compact structures of automotive vehicle bodies and prevent interferences between automotive parts.

Japanese Utility Model Publication 57109921 discloses such a fuel tank. A recess in the bottom surface of the fuel tank causes a projection extending into the fuel tank. This projection separates a lower segment of the interior of the fuel tank into a main chamber and an auxiliary chamber. When the level of fuel in the tank decreases below the top of the projection, the fuel separates into two parts held in the main and auxiliary chambers respectively. A fuel feed line forks into two pipes extending into the main and auxiliary chambers respectively. A change-over valve disposed at the point of this fork selectively connects a common segment of the fuel feed line to either of the two pipes. The forked fuel feed pipes and the change-over valve cooperate to enable both the fuel in the main chamber and the fuel in the auxiliary chamber to be supplied and used fully.The changeover valve and a system controlling the change-over valve cause the whole fuel tank design to be complicated and expensive.

It is an object of this invention to provide a simple fuel tank arragement including two fuel chambers.

In accordance with this invention, a bottom wall of a fuel tank body defines an inwardly extending projection which separates at least a lower segment of an interior of the fuel tank body into a first fuel chamber and a second fuel chamber. Fuel is pumped out of the first fuel chamber. An ejector pump is disposed within the second fuel chamber. A communication pipe connects the ejector pump to the first fuel chamber. A portion of the fuel chamber is returned to the first fuel chamber by way of the ejector pump and the communication pipe. The ejector pump is driven by the return fuel. The ejector pump transports fuel from the second fuel chamber to the first fuel chamber via the communication pipe.

Figure 1 is a diagram of an automotive fuel supply system including a fuel tank arrangement according to a first embodiment of this invention.

Figure 2 is a diagrammatical section of the fuel tank of Fig. 1.

Figure 3 is an enlarged section of the ejector of Fig. 2.

Figure 4 is a sectional view of an ejector in a fuel tank arrangement according to a second embodiment of this invention.

Figure 5 is a sectional view of a portion of a fuel tank agrrangement according to a third embodiment of this invention.

Like and corresponding elements are denoted by the same reference characters throughout the drawings.

With reference to Fig. 1, an automotive fuel supply system includes a first fuel feed line 11 which connects a fuel tank 12 to the inlet of a fuel pump 13. A second fuel feed line 14 connects the outlet of the fuel pump 13 to the inlet of a fuel filter 15 via a damper or silencer 16. A third fuel feed line 17 connects the outlet of the fuel filter 15 to a main fuel injection valve or valves 18 which allow fuel to be admitted into an engine air intake passage or passages 19. A fourth fuel feed line 20 connects the outlet of the fuel filter 15 to an auxiliary fuel injection valve 21 which allows fuel to be admitted into the engine air intake passage 19.

The fuel pump 13 draws fuel from the fuel tank 12 via the fuel feed line 11 and forces it toward the fuel injection valves 18 and 21 via the fuel feed lines 14, 17, and 20, and via the fuel filter 15. The damper 16 removes pulsation from a fuel flow. When a cold engine is started, the auxiliary fuel injection valve 21 is activated to supply additional fuel to the engine.

A pressure regulator 22 has first, second, third, and fourth ports 23, 24, 25, and 26.

The first port 23 is connected to the fuel feed line 17 via a fuel passage 27. The second port 24 is connected to the fuel feed line 20 via a fuel passage 28. The third port 25 is connected to the fuel tank 12 via a fuel return line 29. The fourth port 26 is connected to the engine air intake passage 19 via a pressure introduction passage 30.

A portion of fuel driven by the fuel pump 13 deviates from the fuel injection valves 18 and 21 and moves into the pressure regulator 22 via the fuel passages 27 and 28, passing through the pressure regulator 22 and returning to the fuel tank 12 via the fuel return line 29. The pressure regulator 22 adjusts the rate of this fuel return in accordance with the difference between the pressure in the fuel feed lines 17 and 20 and the pressure in the engine air intake passage 19 so that the pressure in the fuel feed lines 17 and 20 relative to the pressure in the engine air intake passage 19 will be maintained at a constant value. In other words, the pressure regulator 22 maintains the pressure across the fuel injection valves 18 and 21 at a fixed level.

As shown in Fig. 2, the lower wall of the fuel tank 12 has horizontal portions. Another portion of the lower wall of the fuel tank 12 extends upwards from the horizontal portions and thus defines a recess 31 in the bottom surfaces of the fuel tank 12 which accommodates other automotive parts (not shown). The upwardly-extending portion of the tank wall also defines a projection 32 extending into the fuel tank 12. The projection 32 separates a lower segment of the interior of the fuel tank 12 into a main fuel chamber 33 and an auxiliary fuel chamber 34. The top of the projection 32 determines the highest fuel level in the main and auxiliary chambers 33 and 34. The main and auxiliary chambers 33 and 34 communicate with one another via an upper segment of the interior of the fuel tank 12.

The fuel feed line 11 includes a fuel feed pipe 35 extending from the main fuel chamber 33 and through the top wall of the fuel tank 12. The inlet of the fuel feed pipe 35 is located near the floor of the main chamber 33.

A filter 36 surrounds the inlet of the fuel feed pipe 35. The outlet of the fuel feed pipe 35 leads to the fuel pump 13. The fuel is driven by the fuel pump 13 from the main chamber 33 into the inlet of the fuel feed pipe 35 via the filter 36.

The fuel return line 29 includes a fuel return pipe 37 extending into the fuel tank 12 through the top wall of the fuel tank 12. The inlet or the upstream end of the fuel return pipe 37 leads from the pressure regulator 22.

The outlet or the downsteam end of the fuel return pipe 37 is connected to an ejector 40 residing in a segment of the auxiliary chamber 34 near the floor of the auxiliary chamber 34.

As shown in Fig. 3, the ejector 40 has a casing 41 including a conical or tapered shell 41A and an end plate 41B preferably integral with one another. As will be described hereinafter, the end plate 418 forms a holder retaining the fuel return pipe 37. The end plate 41B extends perpendicular to the axis of the conical shell 41A. In addition, the end plate 418 is located at the larger-diameter end of the conical shell 41A. The axis of the conical shell 41A extends horizontally with respect to the fuel tank 12. The ejector casing 41 defines a tapered or conical ejector chamber 42, the axis of which also extends horizontally.

The fuel return pipe 37 coaxially extends into the ejector chamber 42 through the larger-diameter end of the ejector chamber 42.

The segment of the fuel return pipe 37 within the ejector chamber 42 defines an ejector nozzle 43 via which return fuel is injected into the ejector chamber 42. The nozzle 43 extends coaxially with respect to the ejector chamber 42. In addition, the nozzle 43 is radially spaced from the tapered inner surfaces of the casing 41 by a preset annular gap. The casing plate 41 B extends radially between the fuel return pipe 37 and the larger-diameter end of the casing tapered portion 41A and retains the fuel return pipe 37 with respect to the casing tapered portion 41A. The casing plate 41B has a circumferential opening or openings 45 which connect the auxiliary chamber 34 to the ejector chamber 42 to admit fuel into the ejector chamber 42 from the auxiliary chamber 34. These openings 45 constitute inlets for pumped fluid.The smaller-diameter end of the casing tapered portion 41A defines a circular opening 46 in communication with the ejector chamber 42. This opening 46 constitutes an outlet of the ejector 40.

As shown in Figs. 2 and 3, a communication pipe 47 disposed within the fuel tank 12 extends over the projection 32 and connects the ejector 40 to the main chamber 33.

As best shown in Fig. 3, an end of the communication pipe 47 is connected to the smaller-diameter end of the tapered portion 41A of the ejector casing 41, that is, to the outlet 46 of the ejector 40. The inside diameter of this end of the communication pipe 37 is the same as that of the smaller-diameter end of the casing tapered portion 41A. In addition, this end of the communication pipe 47 axially aligns with the smaller-diameter end of the casing tapered portion 41A. The ejector casing 41 is preferably integral with the communication pipe 47. As shown in Fig. 2, the other end of the communication pipe 47 is located near the floor of the main chamber 33.

The wall of the communication pipe 47 immediately above the main chamber 33 has an orifice 48 extending from the interior of the communication pipe 47 and opening onto the outer surface of the communication pipe 47.

In other words, the orifice 48 extends through the wall of the communication pipe 47 immediately above the main chamber 33. The orifice 48 extends along a horizontal line having essentially the same height as the top of the projection 32, that is, as the highest fuel level in the main chamber 33. In addition, the orifice 48 is preferably located immediately below a corner of the communication pipe 47.

A portion of fuel driven by the fuel pump 13 returns to the fuel tank 12 via the pressure regulator 22 and the fuel return line 29.

The return fuel pressurized by the fuel pump 13 is injected via the ejector nozzle 43 into the tapered ejector chamber 42 toward the smaller-diameter end of the ejector chamber 42, that is, toward the ejector outlet 46 and the communication pipe 47. The injection of the return fuel enables fuel to be drawn from the auxiliary chamber 34 into the ejector chamber 42 via the pumped fluid inlets 45 of the ejector 40. The injected fuel and the drawn fuel move from the ejector chamber 42 into the communication pipe 47 via the ejector outlet 46, passing through the communication pipe 47 and then entering the main chamber 33.

As described previously, the return fuel driven by the fuel pump 13 moves from the fuel return line 29 into the main chamber 33 by way of the ejector 40 and the communication pipe 47. The ejector 40 serves as a pump driven by the pressurized return fuel and forcing the fuel from the auxiliary chamber 34 to the main chamber 33. Since the ejector 40 transports the fuel from the auxiliary chamber 34 to the main chamber 33 and then the fuel is drawn into the fuel feed pipe 35, the fuel in the auxiliary chamber 34 can be used fully as the fuel in the main chamber 33.

In cases where the fuel level in the auxiliary chamber 34 is higher than the fuel level in the main chamber 33, when the fuel pump 13 is suspended, siphonage continues the transportation of the fuel from the auxiliary chamber 34 to the main chamber 33. It should be noted that the siphonage is ensured, since the ejector chamber 42 and the communication pipe 47 are fully filled with the fuel at the moment of the initiation of the suspension of the fuel pump 13.

In cases where the fuel level in the auxiliary chamber 34 is lower than the fuel level in the main chamber 33, when the fuel pump 13 is suspended, the orifice 48 prevents siphonage so that the fuel does not move from the main chamber 33 to the auxiliary chamber 34.

Fig. 4 shows a second embodiment of this invention which is similar to the embodiment of Figs. 1-3 except for the following design changes.

In the embodiment of Fig. 4, the section of the ejector casing 41 near its larger-diameter end is non-tapered and thus cylindrical. The opening or openings 45 (see Fig. 3) are omitted from the the casing plate 41B so that the larger-diameter end of the casing 41 is fully closed by the plate 41B. A lower portion of the cylindrical section of the casing 41 has an opening 50 constituting a pumped fluid inlet.

Fuel can be drawn from the auxiliary chamber 34 into the ejector chamber 42 via the pumped fluid inlet 50.

Fig. 5 shows a third embodiment of this invention which is similar to the embodiment of Figs. 1-3 except for the following design changes.

In the embodiment of Fig. 5, a vessel 60 disposed in the auxiliary chamber 34 is secured to the floor of the auxiliary chamber 34.

A lower portion of the side wall of the vessel 60 has an opening 61 via which fuel can enter the vessel 60 from the auxiliary chamber 34. The ejector 40 is disposed within the vessel 60 at a location near the floor of the vessel 60.

In cases where the amount of the fuel remaining in the fuel tank 12 is small, when the fuel level in the auxiliary chamber 34 inclines as shown by the broken lines A and B of Fig.

5 due to a quick turn of the associated automotive vehicle, the vessel 60 usually holds a considerable amount of the fuel and keeps the fuel level higher than the ejector 40 so that the fuel remains drawn from the auxiliary chamber 34 into the ejector 40.

In a first modification to at least one of the previous embodiments of this invention, the fuel pump 13 is disposed within the fuel tank 12. In this case, the inlet of the fuel pump 13 is located near the floor of the main chamber 33, and the outlet of the fuel pump 13 is connected to the damper 16 via a fuel line extending through a wall of the fuel tank 12.

In a second modification to at least one of the previous embodiments of this invention, the end of the communication pipe 47 remote from the ejector 40 may be located above the main chamber 33. This arrangement of the communication pipe 47 prevents siphonage causing a fuel flow from the main chamber 33 to the auxiliary chamber 34. Accordingly, the orifice 48 is omitted from this modification.

Claims

1. A fuel tank arrangement comprising: (a) a tank body having a bottom wall defining an inwardly extending projection which separates at least a lower segment of an interior of the tank body into a first fuel chamber and a second fuel chamber; (b) a fuel feed pipe having an inlet located in the first fuel chamber; (c) an ejector casing disposed in a segment of the second fuel chamber near a floor of the second fuel chamber and defining a tapered ejector chamber and an ejector outlet leading from the ejector chamber, the ejector casing also defining an ejector pumped fluid inlet opening which connects the second fuel chamber to the ejector chamber; (d) a fuel return pipe extending into the ejector chamber and having an outlet residing in the ejector chamber; and (e) a communication pipe connecting the ejector outlet to the first fuel chamber.

2. The fuel tank arrangement of claim 1, wherein the inlet of the fuel feed pipe is located near a floor of the first fuel chamber.

3. The fuel tank arrangement of claim 1, wherein an end of the communication pipe is located near a floor of the first fuel chamber.

4. The fuel tank arrangement of claim 1, wherein the ejector casing is integral with the communication pipe.

5. The fuel tank arrangement of claim 1, wherein the outlet of the fuel return pipe within the ejector casing defines a nozzle extending coaxially with respect to the ejector casing and spaced radially from tapered inner surfaces of the ejector casing by a preset annular gap.

6. -The fuel tank arrangement of claim 1, wherein the communication pipe has an orifice extending through a wall of the communication pipe immediately above the first fuel chamber, the orifice being operative to prevent siphonage causing a fuel flow from the first fuel chamber to the second fuel chamber.

7. The fuel tank arrangement of claim 1, further comprising a vessel disposed in a bottom of the second fuel chamber and having a side opening which allows fuel to enter the vessel from the second fuel chamber, the ejector is disposed in the vessel.

8. An arrangement comprising: (a) a fuel tank having a bottom wall defining an inwardly extending projection which separates at least a lower segment of an interior of the fuel tank into a first fuel chamber and a second fuel chamber; (b) means for pumping fuel out of the first fuel chamber; (c) an ejector pump disposed within the second fuel chamber; (d) a communication pipe connecting the ejector pump to the first fuel chamber; (e) means for returning a portion of the fuel, pumped out of the first fuel chamber by the pumping means, to the first fuel chamber by way of the ejector pump and the communication pipe and thus allowing the return fuel to drive the ejector pump; and (f) means for enabling the ejector pump to transport fuel from the second fuel chamber to the first fuel chamber by way of the communication pipe.

9. The arrangement of claim 8, further comprising means for preventing siphonage causing a fuel flow from the first fuel chamber to the second fuel chamber.

10. The arrangement of claim 8, further comprising a vessel disposed in a bottom of the second fuel chamber and having a side opening which allows fuel to enter the vessel from the second fuel chamber, the ejector pump being disposed in the vessel.

11. A fuel tank arrangement substantially as described with reference to, and as shown in, Figs. 1 and 2 and any of Figs. 3 to 5 of the accompanying drawings.