DE29824208U1 - Fuel tank - Google Patents

Description

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1 LIPPERT, STACHOW, SCHMIDT & PARTNER K/he

Patent Attorneys ■ European Patent Attorneys-European Trademark Attorneys

POBox 30 0208, D-51412 Bergisch Cladbach 18 April 2000

Telephone +49 (0) 22 04.92 33-0
Fax +49 (0) 22 04.6 26 06

KAUTEX TEXTRON GmbH. & Co. KG. 53229 Bonn

Fuel tank

The invention relates to a fuel tank for a motor vehicle according to the preamble of claim 1.

The reservoir, which is generally part of a delivery unit that also contains the fuel pump, has the particular function of ensuring that a sufficient amount of fuel is in the intake area of the fuel pump even under unfavourable operating conditions, for example when cornering for a long time or when the vehicle is in a position that deviates significantly from the horizontal. This requires the presence of a certain minimum amount of fuel in the reservoir.

The electric fuel pump, which is generally arranged inside the reservoir, can be designed in a known manner in two stages, with the first stage of the pump pumping the fuel from the space of the fuel tank surrounding the reservoir into the reservoir. For this purpose, the reservoir can be provided in or near its base with a passage, which can be closed if necessary, through which the fuel can be sucked in by the first stage of the pump. The second stage of the pump takes the fuel from the reservoir and pumps it towards the motor vehicle's engine. The second stage of the fuel pump generally continuously supplies a quantity of fuel per unit of time which is greater than the quantity corresponding to the maximum

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consumption of the engine. Therefore, a device, usually in the form of a pressure regulator, is connected downstream of the fuel pump, in which the excess fuel is diverted and returned to the reservoir.
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Another possibility is that the reservoir is only assigned a single-stage fuel pump, which sucks the fuel out of the reservoir and delivers it to the engine. This fuel pump therefore only fulfils the function of the second stage of the two-stage fuel pump mentioned above. The fuel is delivered from the space in the tank surrounding the reservoir into the reservoir by a suction jet pump, for example, which is kept in operation by the fuel flow that is branched off as excess in the pressure regulator and flows through the return line.

In both of the above-described arrangements and designs, when the tank is filled, the fuel is introduced into the space in the tank surrounding the reservoir. This has the disadvantage that, particularly in the case of fuel tanks with a large base area and/or with a complicated geometry, a larger amount of fuel must be filled into the tank when the fuel system is empty so that fuel also reaches the reservoir in order to start the fuel supply for the engine. This applies in particular to the second of the above-described designs, since effective operation of the suction jet pump requires a sufficient amount of fuel in the reservoir to generate the fuel flow required for operation of the suction jet pump in the return line and the drive nozzle connected to it, whereby there must also be sufficient fuel in the tank space outside the reservoir if the suction jet pump is to pump fuel into the reservoir.

The problems described above occur in particular when a motor vehicle is first refuelled after its manufacture, for which a fuel of a special quality is used.

which is relatively expensive. For this reason too, the vehicle manufacturers where the initial refuelling takes place endeavour to keep the amount of this fuel for the initial refuelling as small as possible. For example, it can be in the order of 1 to 3 litres. However, depending on the design of the tank and the reservoir located therein and also the pump system, it may be necessary to fill in a larger amount of fuel than would be required for the operations carried out on or with the vehicle using the fuel from the initial refuelling.

Accordingly, the invention is based on the object of designing a fuel tank, e.g. for petrol or diesel, of the type described in the introduction in such a way that even with complicated and unfavorable shapes of the tank, under all conditions occurring in practical operation, there is a guarantee that a sufficient amount of fuel is available for the pump supplying the engine even when the total amount of fuel in the tank is very small, as can be the case, for example, when filling up for the first time, but also, for example, when filling up again from a reserve canister after the tank had previously been completely emptied while driving.

This object is achieved by the means specified in the characterizing part of claim 1. Since, when applying the teaching according to the invention, the fuel tank is filled via the reservoir located therein, which has a significantly smaller volume than the tank as a whole, it is ensured in any case that the reservoir is at least partially filled first, so that with a corresponding arrangement of the pump supplying the engine, whose intake area is in any case located in the lower part of the reservoir, the supply of the engine with fuel is ensured even when small amounts of fuel are filled in or remain in the reservoir. The requirement to make the reservoir so liquid-tight, at least in its lower area, that

A minimum amount of fuel remaining in the reservoir can be achieved without difficulty, and in particular without additional expenditure, by making at least the lower part of the reservoir liquid-tight.
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The outlet end of the filling pipe can lead directly into the reservoir, for example by providing the side wall of the reservoir with a corresponding connection to the filling pipe, through which the filling pipe extends into the reservoir in the simplest case. It is of course also possible to connect the outlet end of the filling pipe to the wall of the reservoir, whereby this connection can also be liquid-tight. The filling pipe can also be inserted into the reservoir from above, especially since in many cases the reservoir is open at the top anyway. It is of course also possible to simply let the outlet end of the filling pipe end above the reservoir, which is open at the top.

Some embodiments of the invention are shown in the drawing. They show:

Fig. 1 is a longitudinal section through a first embodiment of a fuel tank for a motor vehicle,

Fig. 2 is a representation corresponding to Fig. 1 of a second embodiment,

Fig. 3 is a representation of a third embodiment corresponding to Fig. 1.

The fuel tank 10 shown in Fig. 1 can be made in various ways from plastic or metal. It is provided with a residual container or reservoir 12 which has a considerably smaller volume than the tank 10 as a whole and is suitably attached to the bottom 14 of the tank 10. The reservoir 12, which is open at the top, ends at a distance from the upper wall 16 of the tank.

The bottom 18 is provided with a central region 20 which is substantially vertical to the longitudinal axis of the reservoir and

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runs parallel to the bottom of the tank 14. The outer region 22 of the bottom 18, which adjoins the middle region 20, is arranged to rise towards the circumference of the reservoir, so that this outer region 18, starting from the middle region 20, has a distance from the bottom 14 of the tank 10 that increases evenly towards the circumference. In order to be able to mount the reservoir 12 within the tank 10 with the necessary stability, it is provided on the underside in the outer bottom region with essentially radial ribs 24, which are arranged at intervals around the circumference of the reservoir and rest on the bottom 14 of the tank.

Inside the reservoir 12, a single-stage electric fuel pump 26 is attached to the middle area 20 of the base 18, to which a line 28 leading to the engine is connected, into which a pressure regulator 30 is connected in a known manner inside the tank 10, from which a return line 32 branches off. The excess fuel quantity is branched off in the pressure regulator 30 and is returned through the return line 32 located outside the reservoir 12 into the space 34 of the tank 10 surrounding the reservoir 12. At the outflow end, the return line 32 is provided with a drive nozzle 36 of a suction jet pump 38, the collecting nozzle 40 of which forms the inflow end of an overflow pipe 42, as shown in the drawing. The overflow pipe is arranged to run essentially vertically, opens into the reservoir 12 at a short distance from the upper boundary of the reservoir and is passed in a liquid-tight manner through the outer region 22 of the base, the arrangement of which enables the suction jet pump 38 to be accommodated in the region below the reservoir 12.

The tank is provided with an opening 44 in its upper wall 16, which is closed by a cover 48 with the interposition of a seal 46. The line 28 and electrical lines 50 for the energy supply of the pump 26 and electrical connection lines 52 and 54 are passed through this cover 48 in a liquid-tight manner. The latter

establish the connection between a respective fill level sensor 56 or 58 and a display or the like. The fill level sensor 56 is arranged in the space 34 of the tank 10 surrounding the reservoir 12, the fill level sensor 58 is arranged within the reservoir 12. Since the reservoir 12 is sealed in the base area and at least in the lower area of the side walls from the space 34 surrounding it within the tank, it is possible, for example in the last phase of consumption of a tank filling, when the space 34 is largely emptied and the remaining fuel is therefore essentially within the reservoir 12, to check the remaining amount of fuel using the fill level sensor 58.

The tank 10 is provided with a filling pipe 60 which extends from the filler neck 62 of the tank into the reservoir 12, the side wall 64 of which is provided with a passage 66 through which the end region 68 of the filling pipe is guided in a liquid-tight manner. The outlet opening of the filling pipe 60 can be closed by a flap 70 which is pivotably attached to the end section 68 and which, when no fuel is flowing through the filling pipe 60 into the reservoir, automatically assumes its closed position and thus prevents fuel from the reservoir from entering the filling pipe.

Since the tank 10 is filled through the filling pipe 60, which can lie in a liquid-tight manner against the inner boundary wall in the area of the nozzle 62, the entire amount of fuel introduced into the tank initially flows into the reservoir 12, so that even when a small amount of fuel is filled in, the reservoir is always filled to such an extent that there is sufficient fuel in the intake area of the pump 26, which is arranged immediately above the central base area 20.

The embodiment according to Fig. 2 corresponds in all essential parts to that according to Fig. 1, so that identical parts are provided with identical reference numerals, each one 100 higher. The only difference between the two embodiments is

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in that the filling pipe 160 of the embodiment according to Fig. 2 is arranged with its outflow-side end section between the upper wall 116 of the tank 110 and the upper boundary of the reservoir 112, i.e. above the latter, in such a way that the fuel flowing out of the filling pipe 160 flows from above into the reservoir 112. Here too, the space 134 surrounding the reservoir is filled by the fuel overflowing from the reservoir 112, the side walls 164 of which, as in the case of Fig. 1, can optionally be provided with openings arranged at a suitable level.

A holder 172 for the end section of the filling pipe 160 is attached to the inside of the upper wall of the tank 116 and can also be closed by a flap 170. In this embodiment too, all of the fuel flowing through the filling pipe 160 initially reaches the reservoir 112, regardless of the flow rate and the amount of fuel, so that this is always filled first.

Fig. 3 shows an embodiment which also corresponds in essential parts to that according to Fig. 1, so that identical parts are also provided with identical reference numerals, each 200 times higher.

The essential difference compared to the embodiments according to Fig. 1 and 2 is that the reservoir is part of a delivery unit 276 which is introduced through an opening 244 in the upper wall 116 of the tank 210, the cross section of the delivery unit 276 initially corresponding to that of the opening 244 or the opening of an intermediate sealing ring 246. The wall 264 delimiting the reservoir can be designed to be deformable for insertion into the tank, so that the delivery unit 276, after it has been at least partially introduced into the tank 210 through the opening 244, experiences a radial enlargement in order to increase the volume of the reservoir by shortening the distance between the front-side boundary parts 277, 248 of the reservoir, which are made of solid material. In Fig. 3, the reservoir of the

Delivery unit 276 is shown in its final form, which it normally retains throughout the entire service life of the tank system. Here too, the pump (not shown) is located within the reservoir 212. The connecting lines are led through the upper limiting part 248, which also forms the closure for the opening 244 in the tank wall 216.

The tank 210 is provided with a filling pipe 260 which extends from the filling nozzle 262 to the delivery unit 276 or the reservoir 212 thereof. For this purpose, the upper limiting part 248 made of rigid material is provided with a tubular extension 280 which runs essentially coaxially to the opening 244 and is connected on the underside to an elastic hose section 264 which limits the wall of the reservoir and to a support frame 282 which is also elastically deformable and is located within the same. The tubular extension 280 has a hole 284 which receives the outflow end of the filling pipe 260 so that when the tank 210 is filled, the fuel supplied through the filling pipe first flows into the reservoir 212. Here, too, there is a guarantee that even if only a small amount of fuel is filled into the tank, it is located within the reservoir 212 and thus in the area of the suction opening of the pump.

The tubular extension 280 is provided with additional holes 286 through which excess fuel can flow out of the reservoir into the surrounding area 230 of the fuel tank during refueling when the reservoir is full. These additional holes 286 are expediently arranged in such a way that they are not opposite the outlet opening of the filler pipe and are therefore not directly exposed to the flow of fuel emerging from the filler pipe and the fuel is initially diverted into the reservoir 212.

Claims (6)

1. Fuel tank for a motor vehicle with a reservoir ( 12 ; 112 ; 212 ) arranged inside the fuel tank ( 10 ; 110 ; 210 ), to which a motor-driven pump ( 26 ; 126 ) is assigned, by means of which the fuel is supplied to the engine, and a filling pipe ( 60 ; 160 ; 260 ) through which the fuel flows into the tank, characterized in that the outlet-side end of the filling pipe ( 60 ; 160 ; 260 ) and the reservoir ( 12 ; 112 ; 212 ) are arranged in such a way that at least part of the fuel flowing through the filling pipe is led directly into the reservoir, which is designed in such a way that at least the lower region of the reservoir is in relation to the surrounding interior ( 34 ; 134 ; 234 ) of the fuel tank is sealed liquid-tight. 2. Fuel tank according to claim 1, characterized in that the outlet end of the filling pipe ( 60 ; 260 ) opens directly into the reservoir ( 12 ; 212 ). 3. Fuel tank according to claim 1, characterized in that the outlet end of the filling pipe ( 160 ) is arranged above the reservoir ( 112 ) which is open at the top. 4. Fuel tank according to claim 1, characterized in that the outlet end of the filling pipe ( 60 ; 160 ; 260 ) is provided with a closure ( 70 ; 170 ; 270 ) which opens under the action of the fuel flowing through the filling pipe. 5. Fuel tank according to claim 4, characterized in that the closure is designed as a flap ( 70 ; 170 ). 6. Fuel tank according to claim 1, characterized in that the reservoir ( 12 ; 112 ; 212 ) has an overflow via which fuel from the reservoir flows into the space ( 34 ; 134 ; 234 ) surrounding the reservoir ( 12 ; 112 ; 212 ) when a certain amount of fuel in the reservoir is exceeded.