FR2793450A1 - Fuel tank for motor vehicle comprises flexible bladder inside rigid shell and has pressurization system for space between bladder and shell to direct fuel through pipe to engine - Google Patents

Abstract

The motor vehicle fuel tank has a flexible bladder (2) which contains the fuel and is arranged inside a rigid shell (1). The engine (8) is supplied by a pipe (80) sealed inside the bladder. The rigid shell is sealed and includes a pneumatic compressor (4) to pressurize the space (10) between the rigid shell and the bladder. The pressure is sufficient to direct the fuel contained in the bladder through the pipe towards the engine.

Description

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 The present invention relates to a fuel tank for a vehicle powered by an internal combustion engine, such as, in particular, a motor vehicle.

 More specifically, the fuel tank which is the subject of the invention is of the type consisting of a rigid shell inside which is housed a flexible pocket containing the fuel, the supply of fuel to the engine being done at by means of a pipe which penetrates in a sealed manner inside said pocket.

 This type of tank, well known, has the advantage of avoiding the emanation of hydrocarbon vapors contained in the tank, since the fuel is confined inside the pocket.

 The pocket is hermetically closed, and consists of a thin, deformable membrane, for example made of rubber; as the fuel is used, the pocket empties, and its volume decreases since the air cannot enter it; during filling, it inflates again as a result of the arrival of the fuel inside the pocket, to occupy a volume corresponding approximately to the interior volume of the hull.

 As the state of the art in this matter, mention may be made of document JP-8091060.

 The invention aims to allow the use of such a tank in a practical and safe manner on a vehicle, in particular on a motor vehicle, this while eliminating the presence of a fuel supply pump. \ ers to the engine, and particularly to the engine injection system.

 This objective is achieved, in accordance with the invention, thanks to the fact that the tank comprises means for pressurizing the interior space of the shell, outside the pocket, at a pressure sufficient to discharge the fuel contained in the pocket, via the engine supply line, towards the latter.

 Thus, it is not necessary to use a pump for the transfer of fuel, the fuel being driven from the tank by the pressure exerted on the pocket.

 These pressurization means can simply consist of a pneumatic compressor.

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Furthermore, according to a certain number of additional, non-limiting characteristics of the tank which is the subject of the invention: - the compressor is connected to the shell by a pipe provided with a non-return valve; - It includes a solenoid valve adapted to achieve rapid depressurization of said interior space; - It equips a vehicle whose starting and stopping is done by means of a control circuit actuated by a key, and the pressurization means are actuated automatically as soon as the ignition is switched on; - the solenoid valve is actuated automatically as soon as the ignition is switched off; - it is fitted with a pressure sensor suitable for measuring the pressure prevailing inside the hull; - it has a filling spout provided with a non-return valve; - It has a filling chute provided with a closure cap, locking means preventing the removal of the cap when the interior space of the shell is pressurized; - These locking means comprise at least one piston, one of the faces of which is exposed to the pressure prevailing in the interior space of the shell, while its other face is subjected to the action of a return spring acting in the direction of unlocking; - Access, for filling, requires the opening of a hatch, and the above-mentioned solenoid valve is actuated automatically as soon as this hatch is opened; - the flexible bag rests on mass sensors mounted on the bottom of the hull, adapted to ensure gauging by weighing the fuel; - The engine fuel supply circuit includes a return line which is provided with a nozzle allowing a rise in pressure greater than the value of the pressurization of the interior space of the hull; - pressurization is carried out at a value of the order of 3 bar (3.105 Pa).
Other characteristics and advantages of the invention will appear from the description and the appended drawing, FIG. 1, which very schematically represents a fuel tank in accordance with the invention, as well as the annexed circuits in connection with its operation.

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 In this figure, the tank, seen in vertical section, essentially consists of a rigid external shell 1, an internal flexible pocket 2, housed inside the shell, and a closure cap 3.

 The shell 1 has a rigid wall, made of metal or plastic, and has the shape of a relatively flat box with horizontal bottom (bottom) and top walls, the interior space 10 of which constitutes a sealed enclosure. In known manner, the shell is provided with a filler neck 11, of tubular shape, the neck of which carries a sleeve 12, capable of receiving the closure plug 3.

 The connection between the plug 3 and the sleeve 12 is of a known type, for example of the bayonet type, allowing these two elements to be joined and separated by rotation, in one direction or the other, over a fraction of a turn.

 The flexible bag 2 has a wall consisting of a thin and deformable membrane, made of a synthetic material which is mechanically resistant to pressure, and chemically resistant to hydrocarbons.

 The pocket is shaped to occupy substantially the interior of the shell 1 when it is full.

 It has a tubular part 21 which engages in the chute 11, being applied intimately against the interior wall of this chute.

 Preferably, this tubular part 21 is fixed to the chute, for example by gluing, at least in its upper end zone, so that its mouth is always open, even when the pocket is completely empty.

 The bottom 14 of the shell 1 is flat.

 The bottom 20 of the pocket is preferably rigid or semi-rigid, and it rests on the shell bottom 14 by means of mass sensors 100.

 These are of known type, for example with strain gauges.

 In the upper part of the chute 11 is arranged a non-return valve 13, which allows the introduction of fuel-referenced C in the figure-but prevents its expulsion from the bottom up, outwardly through said chute.

 In the figure, the bag is shown in a semi-filled state (half full), and the enclosure 10 is not pressurized.

 When the enclosure 10 is pressurized, the pocket is also under pressure and the membrane constituting the pocket retracts on the fuel to discharge it. The fuel cannot reach the closure cap 3, which avoids the problems of soiling and improves safety, thanks to the presence of the non-return valve 13.

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 The reference 8 designates an internal combustion engine of the diesel or petrol type, equipping the vehicle concerned.

 The fuel circuit comprises, in a known manner, a fuel supply line, referenced 80, to the engine, and more precisely to its injection system, as well as a surplus return line, referenced 81.

 These two pipes pass through an airtight passage part forming a seal, referenced 120, mounted in the upper wall of the shell 1.

 They also pass through the upper wall of the pocket 2, in a sealed manner.

 Line 80 descends to the bottom of the pocket, so as to be able to suck the fuel whatever the level, practically until the pocket is empty.

 On the other hand, the return pipe 81 opens directly below the upper wall of the pocket 2.

 Inside the shell, the two pipes 80, 81 are deformable, and have a length sufficient to allow them to follow the deformations of the pocket, by forming serpentines.

 Preferably, the lower end of the pipe 80 is fixed to the bottom 20 of the pocket, so that its mouth is kept constantly near the bottom 20, whatever the deformation of the pocket.

 On the return line 81 is mounted a nozzle which allows a pressure rise greater than the pressurization pressure in order to avoid a pressure drop which would limit the return fuel flow, or even the discharge.

 The arrows f and g respectively symbolize the supply of fuel to the engine, and the return of the excess fuel to the tank.

 The reference 4 designates a pneumatic compressor, which is connected to the upper wall of the rigid shell 1 by means of a pneumatic duct 41 on which there is a non-return valve 42.

 This valve allows the passage of compressed air from the compressor 4 to the tank, but prevents the flow of air in the opposite direction.

 The reference 40 symbolizes a circuit for controlling the starting and stopping of the compressor 4.

 On one side of the tank is mounted a high-flow solenoid valve 5, the opening of which controls the enclosure 10 being brought to rapid atmospheric pressure.

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 On the top of the shell 1 is mounted a pressure sensor 9, of known type, which permanently measures the pressure prevailing in the enclosure 10.

 The reference 6 designates an access hatch to the filling plug 3.

 This hatch is of known type, for example articulated around an axis 61.

 A contactor 60 adapted to provide a signal representative of the closed or open state of the hatch 6 is provided.

 In the drawing, the reference 6 ′ corresponds to the opening of the hatch, shown in broken lines.

 Reference 7 designates the vehicle ignition key.

 As is well known, the key actuates the control circuit for starting and stopping the vehicle.

 The closure plug 3 is equipped with a locking system capable of preventing the removal of the plug.

 In the figure, this system is very schematically shown in the form of a locking rod 31, the end of which enters a bowl provided in the wall of the plug. The rod 31 is the rod of an electromagnet.

 Depending on the state of the electromagnet, the rod 31 is in extension, then locking the plug 3, or on the contrary is retracted, then releasing the plug 3 and authorizing its removal, which makes it possible to fill the reservoir.

 Reference 50 designates the control circuit of the solenoid valve 5.

 This circuit is connected to the key contact system 7 and to the detector 60 for closing the hatch 6.

 The key contact circuit 7 is also connected to the control circuit 40 of the compressor 4.

 Finally, the pressure sensor 9 is connected to a circuit 90 which, on the one hand, controls the electromagnet 30 and, on the other hand, is connected to the circuit 40.

 The circuit 50 is adapted to control the solenoid valve 5 in the direction of bringing the enclosure 10 to atmospheric pressure when the contact is not switched on, which corresponds to the state "0" in the figure, and when the hatch 6 is open.

 If one of these two conditions is not met, the solenoid valve 5 remains closed.

 However, this solenoid valve can advantageously be controlled voluntarily, if necessary by a manual control member 500.

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 The compressor 4 is chosen to develop a pneumatic pressure of constant and determined value, which corresponds to the operating pressure of the engine injection system.

 Generally, this pressure has a value of 3 bar.

 The circuit 90 is adapted to supply to the circuit 40 a signal indicating whether the pressure measured by the sensor 9 is indeed equal, within a given range of tolerances, to the required service value, in this case 3 bar.

 The circuit 90 is also adapted to control the electromagnet 30 in the direction of locking the plug 3 when the pressure measured by the sensor 9 exceeds a certain value, slightly higher than atmospheric pressure and, on the contrary, to control the electromagnet in the unlocking direction, when the pressure has dropped below this value.

 Furthermore, the control circuit 40 of the compressor 4 actuates the latter only when the ignition is on, which corresponds to the state referenced "1" in the figure.

 The system which has just been described operates in the manner explained below.

 With the vehicle stationary, the tank containing a certain amount of fuel, and the interior of the hull being at atmospheric pressure, the user switches on the ignition, which causes the solenoid valve 5 to close and the compressor start-up 4.

 Compressed air is therefore introduced into the enclosure 10, until the pressure of 3 bar is reached. Compressor 4 then stops automatically.

 During the running of the vehicle, the fuel is brought to the engine 8 via the line 80, any surplus (not used by the engine) returning to the tank through the line 81. The nozzle 82 of the return line is for example calibrated to a value 3.5 bar. The pocket is gradually emptying.

 The compressor automatically starts again when the pressure value, measured continuously by the sensor 9, drops below a predetermined threshold, for example 2.8 bar, thanks to the control circuit 90.

 The interior space 10 of the shell remains pressurized, even if the compressor 4 is stopped, because the shell is sealed, and due to the presence of the non-return valve 42.

 This is also the case when the vehicle is stopped (contact removed) with the hatch 6 closed.

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 When the user wants to replenish the fuel tank, it is necessary to depressurize the enclosure 10, on the one hand to avoid the backflow by the spout 11 of the fuel likely to remain in the pocket, on the other hand to allow the deformation of the pocket in the direction of its swelling as a result of filling.

 This therefore supposes the opening of the solenoid valve 5.

 For this, it is necessary first of all that the vehicle is stopped, the contact being removed.

 When the user lifts the hatch 6, in order to access the filling plug 3, the detector 60 sends a hatch opening signal to the circuit 50.

 The latter then controls the opening of the solenoid valve 5, which ensures rapid, almost instantaneous venting of the enclosure 10.

 Consequently, the pressure in this enclosure drops suddenly and the pressure sensor 9 sends a signal corresponding to the circuit 90, which then controls the unlocking of the plug 3 by retraction of the electromagnet rod 31.

 The user can then remove the plug 3 and fill the tank, this in a conventional manner.

 This operation finished, it closes the hatch 6. the solenoid valve 5 closes again automatically as soon as the next contact is made.

 The mass sensors 100 are connected to a computer which controls the display on the dashboard of the volume of fuel contained in the pocket, this volume being, of course, a function of the mass measured by the sensors.

 It will be noted that this principle of gauging by weighing is known per se, for example from the document FR-A-2 533 695.

 According to a possible variant of the fuel circuit, the pipe 80 passes through the wall of the pocket 2 in the lower part, for example the bottom 20 of the pocket, by means of an assembly which is therefore not dependent on the deformation of the poached. It can therefore be rigid.

 Likewise, the pipe 81 can be connected to the chute 21, just below the non-return valve 13, this connection being compatible with the deformable nature of the pocket, even if the pipe is rigid.

 For locking the plug 3, use may be made of a closure of the type usually used for autoclaves, in which the locking of the plug is achieved by a piston, one of the faces of which is exposed to the pressure prevailing in the pressurized tank. , which is constituted here by the enclosure 10.

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 The other side of the piston is biased by a return spring. Thus, in the event of depressurization of the enclosure, the spring automatically moves the piston in the unlocking direction, allowing opening. The opposite effect occurs automatically when the enclosure is pressurized.

 Of course, a pneumatic connection, for capturing and transferring the pressure, is provided between the interior of the shell 1 and the autoclave-type plug.

 In a particularly advantageous variant, in which it is the plug 3 itself which acts as a non-return valve, in place of the valve 13, the locking piston is integrated into this plug, and is exposed directly to the pressure of the air pocket in the filler neck, above the fuel level.

Claims (14)

1. Fuel tank for a vehicle powered by a heat engine, which consists of a rigid shell (1) inside which is housed a flexible pocket (2) containing the fuel, the engine supply (8) in fuel by means of a line (80) which penetrates in a sealed manner inside this pocket (2), characterized in that the hull (1) is sealed and that it comprises means (4 ) pressurizing the space (10) inside the shell (1), outside said pocket, at a pressure sufficient to discharge the fuel contained in the pocket, via the line (80), towards the engine (8).  2. Tank according to claim 1, characterized in that said pressurization means (4) consist of a pneumatic compressor.  3. Tank according to claim 2, characterized in that the compressor (4) is connected to the shell (1) by a pipe (41) provided with a non-return valve (42).  4. Tank according to one of claims 1 to 3, characterized in that it comprises a solenoid valve (5) adapted to achieve rapid depressurization of said space (10).  5. Tank according to one of claims 1 to 4, fitted to a vehicle whose starting and stopping is done by means of a control circuit actuated by a key (7), characterized in that said means pressurization (4) are actuated automatically as soon as the ignition is switched on.  6. Tank according to claims 4 and 5 taken in combination, characterized in that the solenoid valve (5) is actuated automatically upon switching off.  7. Tank according to one of claims 1 to 6, characterized in that it is provided with a pressure sensor (9) adapted to measure the pressure prevailing inside the shell (1).  8. Tank according to claim 7, characterized in that it has a filling spout (11) provided with a non-return valve (13).  9. Tank according to one of claims 1 to 7, characterized in that it has a filling chute (11) provided with a closure plug (3), locking means (30, 31) prohibiting the removal of the plug (3) when the interior space of the shell (1) is pressurized. <Desc / Clms Page number 10>  10. Tank according to claim 9, characterized in that said locking means comprise at least one piston, one of the faces of which is exposed to the pressure prevailing in the interior space (10) of the shell (1), while that its other face is subjected to the action of a return spring acting in the unlocking direction.  11. Tank according to claim 4, access to which, with a view to filling, requires the opening of a hatch (6), characterized in that the solenoid valve (5) is actuated automatically as soon as this hatch (6).  12. Tank according to one of claims 1 to 11, characterized in that the flexible bag (2) rests on mass sensors (100) mounted on the bottom of the hull, adapted to ensure gauging by weighing the fuel .  13. Tank according to one of claims 1 to 12, characterized in that the fuel supply circuit of the engine (8) comprises a return line (81) which is provided with a nozzle (82) allowing a pressure build-up greater than the value of the pressurization of the interior space (10) of the shell (1).  14. Tank according to one of claims 1 to 13, characterized in that the pressurization is carried out at a value of the order of 3 bar (3.105 Pa).