FR2816553A1 - Automobile fuel reservoir with integrated positive reserve, has settling chamber communicating with fuel tank with a water collect system - Google Patents

Abstract

The container (22) has a settling (decanting) chamber (28) communicating with it, from which the fuel pipe (24) is fed with fuel. The end zone of the fuel pipe is bent so as to direct the fuel tangentially to the peripheral wall of the reservoir. The container (22) has a lower water collect shutter (36) delimiting with the base of the reservoir the settling chamber. The shutter is has a hole (38) feeding into the settling chamber. The hole is fitted with a valve (40) made from a material whose density is less than water but greater than the fuel. Fuel reservoir of the integrated positive reserve type having: (1) a container (22) placed in the reservoir and communicating with it; (2) a fuel pump (16) vertically fitted into the container and; (3) an engine fuel return pipe (19) fitted with a venturi (34) opening into the container so as to cause suction of fuel by the pipe. An Independent claim is included for - a method of emptying the fuel reservoir..

Description

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 The present invention relates to a fuel tank for a motor vehicle of the type with integrated positive reserve. It also relates to a method of emptying such a tank.

 Fuel tanks of this type conventionally comprise a proper tank, a container placed in the tank and in communication with the latter, fuel pumping means placed in the container and means for filling the container comprising a generally upright conduit in the container and a fuel return tube from the engine provided with a venturi opening into the container so as to cause a suction of fuel through the conduit.

 The container filling means are effective in maintaining a sufficient level of fuel in the container, even when the tank contains little fuel.

 However, the bottom of the tank is often filled with a certain amount of water caused by condensation phenomena. Consequently, the venturi, which causes a suction from the bottom of the tank leads, into the container, all the stagnant water in the bottom of the tank as well as all the pollutants in suspension and heavier than the fuel.

 The presence of water in the bottom of the tank and in the bottom of the container is a major drawback due to the very high exhaustion capacity of this type of tank. In fact, practically all the water contained in the tank is sent to the engine.

 This water oxidizes the metal parts. In addition, it forms oxides which return to the reservoir and risk strongly altering the constituent elements of the pumping members which are associated with it.

 The object of the invention is to overcome this drawback.

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It therefore relates to a fuel tank of the aforementioned type, characterized in that the tank comprises a settling chamber in communication with the tank, from which the conduit is supplied with fuel.

 Thus, even when the tank contains little fuel, only fuel is sucked up by the pumping means, the water being kept in the lower part of the container.

 This fuel tank may also include one or more of the following characteristics, taken in isolation or in any technically possible combination: the free end region of the duct is bent so as to direct the fuel tangentially to the peripheral wall of the tank; the reserve comprises a lower partition for collecting water defining with the bottom of the container said settling chamber, said partition being provided with an orifice opening into the latter; the orifice of the partition is equipped with a valve made of a material whose density is less than that of water and greater than that of fuel; it comprises means for drawing off the decanted water from the decanting chamber, the container comprising a decanting and storage compartment for water supplied by the drawing off means; the decantation and storage compartment is provided with an upright pipe, a first end of which is placed in the bottom of the decantation chamber and the opposite end of which extends into an upper end zone of said decantation compartment and of storage, the water drawing means comprising a pipe, one end of which is placed in the vicinity of the venturi and the other end of which opens into the settling and storage compartment;

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 the decantation and storage compartment is provided with a drain tube, one end of which is placed in the bottom of said compartment and the opposite end of which is connected to the fuel return tube by means of a valve distributor; it comprises a fuel suction chamber from which the filling duct extends, which suction chamber communicates with the decantation chamber via a passage located at a height suitable for avoiding a passage d water from the settling chamber to the suction chamber; it includes means for measuring the fuel level in the tank and means for detecting the water level in the container; said measurement and detection means comprise a first float disposed in the tank, a second float disposed in the decantation chamber and / or in the decantation and storage compartment, and a computer associated with a variable resistance whose resistance value varies as a function of the fuel level detected by the first float and comprising means for comparing the value of the variable resistance with a set of predetermined resistance values each corresponding to a fuel level in the tank, a connection control switch an additional resistance in series with the variable resistance being provided, said switch being piloted by the second float so as to give the resistance a value which corresponds to a maximum level of water in the container and so that the total value of the variable resistance varies depending on the water level in the recipient ; the variable resistance and the additional resistance are placed on a common support.

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 the second float is associated with a magnet controlling the opening and closing of the control switch; the container comprises means for discharging the water present in the fuel contained in the container; the means for discharging the water comprise a tube substantially parallel to the axis of the container and the lower end of which opens into the lower part of the latter, at a level below the suction level of the pumping means, while the the upper end opens into the tank, and means for creating an overpressure in the container.

 The invention also relates to a method of emptying a tank as defined above, characterized in that it comprises the steps consisting in: - disconnecting the fuel return tube; and - create, in the fuel return tube, upstream of the valve distributor, a depression so as to close the first valve, open the second valve and draw the bottom of the water storage compartment.

Other characteristics and advantages of the invention will emerge from the following description, given solely by way of nonlimiting example, and made with reference to the appended drawings in which:
Figure 1 shows a block diagram of a fuel tank according to the invention for supplying a diesel type engine; - Figure 2 is a view, on a larger scale, of the tank of Figure 1, showing the constitution of the positive reserve; - Figure 3 is a top view of the reserve of Figure 2; - Figure 4 shows an embodiment of the means for measuring the amount of stagnant water in the settling chamber; and

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Figure 5 shows another embodiment of a positive reserve of a tank according to the invention.

 In FIG. 1, there is shown, schematically, the power system of a motor vehicle engine designated by the general reference 10.

 In the embodiment shown, the engine 10 is constituted by a diesel engine of the common rail type.

 The engine supply system 10 comprises, as is conventional, a fuel tank 12 provided with a filler neck 14. The tank is provided with a drawing device constituted by a booster pump 16 delivering fuel to a high pressure pump 18 associated with a protective filter 20, for example a paper filter, which high pressure pump supplies the engine 10. The excess fuel is reinjected into the tank via a line C extending into the tank by a fuel return tube 19.

 Furthermore, the reservoir 12 includes a reserve 22, of the positive reserve type, consisting mainly of a container in which the booster pump 16 is placed and in which the fuel return tube 19 opens.

 The reserve 22 communicates with the reservoir 12.

When the level in the latter is low, the reserve 22 is filled so that its level is sufficient for the booster pump 16 to operate effectively.

 To this end, and with reference also to FIGS. 2 and 3, the reserve 22 comprises, internally, a conduit 24 generally erected vertically from a lower end zone to an upper end zone of the reserve at which the conduit 24 forms a bend 26 extending

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 generally parallel to the wall constituting the container 22.

 Furthermore, the reserve 22 comprises a decantation chamber 28 by means of which the reserve communicates with the rest of the reservoir 12. It can in fact be seen that, in the zone opposite the chamber 28, the wall constituting the container 22 is perforated and delimits a housing 30 in which a filter 32 is placed, for example a filter provided with a porous mesh surface adapted to the capacities of the pump 16 and forming folds turned towards the outside of the container 22 so as to present maximum active area.

 To force the fuel into the conduit 24, the fuel return tube 19 comprises, at its free end, a venturi 34 positioned opposite the lower or upstream end of the conduit 24 so that, in operation, the fuel coming from the engine 10, injected into the reserve via the venturi 34, causes a suction of fuel through the conduit 24.

 Furthermore, the reserve 22 is provided with a lower partition 36 which delimits, jointly with the constituent wall of the reservoir on which the reserve 22 is mounted, the settling chamber 28 and which, as will be described later, performs a collection of the separated water under the effect of the rotation of the fuel in the reserve 22.

 This partition 36 is provided with an orifice 38 which opens into the settling chamber 28 and which is closed by a valve 40 made of a material with a density less than that of water and greater than that of fuel.

 The valve 40 is mounted movable relative to the partition 36 between a first position, visible in FIG. 2, in which it closes the orifice 38 and a second position (not shown), in which it

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 releases the orifice 38 and authorizes a flow of water towards the decantation chamber 28.

 A guide 42, on the one hand, guides the valve during its movement and, on the other hand, constitutes a stop against which the valve 40 comes to bear in its second position.

 Furthermore, the drawing-off device comprises a strainer 44, of the conventional type, ensuring filtration of the particles in the reserve 22, disposed opposite the pump 16.

 Finally, the tank 12 is completed by means for measuring the quantity of fuel in the tank 12 and for detecting water in the reserve 22.

 Referring in particular to FIGS. 2 and 4, these measurement and detection means comprise, on the one hand, a first float 46 placed in the tank and at least a second float 48 placed in the decantation chamber 28 and provided with 'a magnet 49 and, on the other hand, a computer 50 (Figure 1) associated with a variable resistor 52 whose resistance value varies linearly as a function of the fuel level in the tank, the first float 46 causing the displacement of a brush 53 for adjusting the value of this resistance 52.

 Furthermore, the computer 50 includes means for reading, of the conventional type, the value of the resistor 52 and software means for comparing this value with a set of predetermined values, stored in memory, each corresponding to a fuel level. in the tank 12 so as to provide a display 54 with the calculated level of fuel in the tank.

 The second float 48, meanwhile, is guided between partitions integral with the container 22 and causes the actuation of a switch 56, by means of the magnet. As can be seen in FIG. 4, the flipping of the switch causes, in response, the

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 series connection of an additional fixed resistor 58 on the variable resistor 52 so that the consecutive increase in the resistance measured by the computer 50 constitutes a means of detecting a threshold water level in the reserve 22.

réservoir et une deuxième partie 54b dédiée à l'affichage d'un signal d'alarme traduisant la présence d'eau dans la réserve. Note that, for example, the display 54 is provided with a first part 54a, dedicated to the display of information relating to the fuel level in the

tank and a second part 54b dedicated to the display of an alarm signal indicating the presence of water in the reserve.

 It will be noted that, even after this threshold is exceeded, that is to say even after connection of the fixed resistance, the computer retains the capacity to provide a gauging function, the variable resistance continuing to vary linearly as a function of the fuel level. in the tank.

 It will also be noted that, preferably, the two resistors are placed on a common support in order in particular to avoid the appearance of relative variations in temperature liable to cause disturbances in the measurements made.

 The tank which has just been described operates in the following manner.

 As is conventional, the booster pump 16 sends fuel under a pressure of a few bars to the high pressure pump 18 via the filter 20, which pump 18 supplies the engine 10 with fuel.

 The excess fuel is reinjected into the reserve 22 via the line C and the fuel return tube 19.

 The reserve 22, for its part, is supplied with fuel, on the one hand, by the tube 19 and, on the other hand, via the perforated part of the wall constituting the reserve and the filter 32.

 Note that the total section of the passage through which the fuel flows from the tank to the chamber

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 the settling tank 28 is large enough for the fuel to circulate at a reduced speed so that the water settles and stagnates in the bottom of the settling chamber 28.

 Furthermore, the venturi 34 equipping the free end of the fuel return tube 19 causes, as mentioned previously and in a manner known per se, a suction of fuel through the conduit 24.

 Downstream, that is to say at the bent end 26, the fuel rotates all the fuel contained in the reserve. This rotation presses against the wall of the reserve 22 the droplets of water which could have been sucked through the conduit 24.

 Thus, the booster pump, located in the central part of the reserve, mainly pumps only fuel.

 This water is then collected by the lower partition 36.

 As soon as the amount of stagnant water increases appreciably, the valve 40 opens, thereby causing water to flow through the orifice 38.

 With regard to the measurement means, the float 46 of the tank causes a change in the value of the variable resistor 52 as a function of the level of fuel in the tank. This resistance value, measured by the computer 50, is presented on the display 54 and, in particular, on the part 54a provided for this purpose.

 Furthermore, as soon as the quantity of water in the decantation chamber 28 increases up to a threshold value from which it could be sucked through the conduit 24, the second float 48 causes the activation of the switch 56 and placing the fixed resistor 58 in series with the variable resistor 52.

 The consecutive increase in the value of the total resistance, reflecting the presence of an amount of water in the reserve greater than this threshold value,

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 is detected by the computer 50 which causes, in response, the display of an alarm signal on the part 54b of the display provided for this purpose.

 The fuel tank which has just been described, which is provided with a settling chamber for bringing fuel to an area in which this fuel is pumped, avoids any risk of pumping water. Furthermore, even if water is entrained in this zone, this water is separated from the fuel and then, after having been collected, is reintroduced into the settling chamber.

 We will now describe, with reference to FIG. 5, another embodiment of the reserve.

 As in the embodiment described above, the reserve, designated by the general reference numeral 57, comprises a booster pump 58 ensuring the supply of fuel to the engine of the vehicle via a high pressure pump (not shown), a conduit 60 erected and bent ensuring the filling of the reserve 57 under the action of a venturi 62 fitted to the free end of a tube 64 for fuel return.

 According to this exemplary embodiment, the lower or upstream end of the duct 60 extends from a suction chamber 66 which communicates, via a passage 68, with a primary settling chamber 70, which also communicates with the lower part of the tank, via a filter 72.

 The passage 68 is positioned at a sufficient height so that the water present in the bottom of the settling chamber 70 does not reach the suction chamber.

 Furthermore, the reserve is provided with a main decantation and water storage compartment, designated by the general reference 74, which is supplied with water by means

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 drawing comprising, on the one hand, an upright pipe 76 extending from the bottom of the primary settling chamber 70 and a pipe 78 provided with a first end 80 placed under the influence of the venturi 62 and of a opposite end 82 opening into the settling and storage compartment 74, in the upper part thereof.

 The settling and storage compartment 74 is provided with floats 84 ensuring a detection of the water level and each carrying a magnet 85 controlling a switch 86 controlling the connection of an additional resistance in series with a variable measurement resistance itself. even connected to a computer (not shown), identical to the resistor and to the computer described above with reference to Figure 2 and Figure 4.

 The decantation and water storage compartment is further provided with a drain tube 88 plunging, through a first lower end 89, into the compartment 74 and the opposite end of which is connected to the fuel return tube 64 by through a three-way distributor 90 comprising a valve 92 of duckbill type placed on the fuel path to the reserve and a ball valve 94 located downstream of the drain tube 88.

 Finally, it can be seen in FIG. 5 that, in order to evacuate the water present in the reserve, it is provided with a cover 95 for closing and a tube 96 for evacuating excess fuel erected generally parallel to the axis of the reserve and extending from a small distance from the bottom of the reserve, and generally, from a level lower than that of the suction port of the booster pump 58, this drain tube opening into the tank.

 Such evacuation means can also be provided in the embodiment described above with reference to FIGS. 1 to 4.

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According to this embodiment, the reservoir operates in the following manner.

 As in the embodiment described above with reference to FIGS. 1 to 4, the conduit 60 ensures the filling of the reserve 56 by taking fuel from the suction chamber 66, under the action of the venturi 62 equipping the fuel return tube 64.

 It will be noted that the fuel flowing in the fuel return tube closes the valve 94 fitted to the drain tube 88, the other valve being open.

 Furthermore, the flow of fuel from the upright conduit 60 being greater than the flow of fuel sucked in by the booster pump, and the reserve being formed by the cover 95, a slight overpressure is created in the reserve, the excess fuel does not can then escape only through the discharge tube 96.

 This tube, which draws liquid from its lower end in an area located at a low level of the reserve, lower than that of the orifice of the booster pump, thus evacuates the water which would be likely to collect in this area .

 The upright conduit 60 delivers, by its bent upper end, fuel in the upper zone of the reserve 56, that is to say in the zone in which the booster pump 58 is located.

 In doing so, and as mentioned above, it rotates the fuel filling this zone and therefore causes separation of the water droplets which could have been sucked in through line 60.

 As in the embodiment described above, the booster pump 58, located in the central part of the reserve 56, only substantially sucks fuel, the water droplets being pressed against the peripheral wall of the reserve.

 This water can then be discharged through the tube 96 while the water contained in the fuel from

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 from the tank and not sucked in by the tube 76 is recovered by the primary settling chamber 70 which communicates with the rest of the tank via the filter 72.

 Note that the fuel flow through the latter is low enough to allow the water to settle at the bottom of this chamber 70 and to allow the fuel to flow to the suction chamber 66 via the passage 68 .

 Furthermore, the pipe 78, extending between the suction chamber 68 and the decantation and storage compartment 74, puts the latter under vacuum, under the effect of the venturi 62.

 This drop in pressure causes a suction of the stagnant mixture in the bottom of the primary settling chamber 70 by means of the upright pipe 76 and the pouring of this mixture into the compartment 74.

 Note that the flow is low enough for the water, which is denser than the fuel, to fall and collect at the bottom of this compartment.

 Thus, the fuel, located in the upper part, is sucked through the line 78 and is injected into the suction chamber 66.

 Furthermore, and as described above, the float 84, equipping the decantation and storage compartment 74, and equipped with its magnet 85, controls the switch 86 as soon as the water level in this compartment reaches a value of predetermined threshold so as to trigger an alarm.

 Once the alarm has been triggered, or as a preventive measure each time the filter cartridge of the filter 20 is changed, the settling and storage compartment 74 is emptied.

 Note that, as mentioned above, during normal operation of the tank, the valve 94 of the three-way distributor 90 fitted to the drain tube 88

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 is closed, while the other valve 92 is open, due to the pressure prevailing in the current return tube 64.

 To empty the decantation and storage compartment, with the vehicle stopped, it is simply necessary to disconnect, on the engine side, the fuel return tube 64.

 A depression is created in the part of the fuel return tube 64 located upstream of the valve distributor 90, the effect of which is first of all to block the non-flow valve 92 located on the path of the fuel in the tube fuel return 64 to the suction chamber 66, and to open the valve 94 fitted to the drain tube 88, then to cause a suction from the bottom of the water storage compartment.

 It will be noted that the spring fitted to the ball valve 94 is calibrated so that the fuel pressure cannot open it when the vehicle is overturned following an accident and that the fuel return line is damaged between the engine compartment and the tank. .

Claims (13)

CLAIMS 1. Fuel tank for a motor vehicle, of the type with positive reserve integrated (22; 57), comprising a tank proper, a container (22; 57) placed in the tank and in communication with the latter, pumping means fuel (16; 58) placed in the container (22; 57), and means for filling the container comprising a conduit (24; 60) generally vertically erected in the container and a fuel return tube (19; 64) from the engine provided with a venturi (34; 62) opening into the container so as to cause a suction of fuel through the conduit, characterized in that the container (22; 57) has a decantation chamber (28; 70 ) in communication with the tank, from which said conduit is supplied with fuel.  2. Tank according to claim 1, characterized in that the free end zone of the duct (24; 60) is bent so as to direct the fuel tangentially to the peripheral wall of the tank.  3. Tank according to one of claims 1 and 2, characterized in that the reserve (22; 57) comprises a partition (36) lower for collecting water delimiting with the bottom of the container said settling chamber (28), said partition being provided with an orifice (38) opening into the latter.  4. Tank according to claim 3, characterized in that the orifice (38) of the partition is equipped with a valve (40) made of a material whose density is less than that of water and greater than that of fuel .  5. Tank according to any one of claims 1 to 4, characterized in that it comprises means (62,76, 78) for drawing the decanted water from the decantation chamber, and in that the container <Desc / Clms Page number 16>  comprises a compartment (74) for decanting and storing water delivered by the drawing means.  6. Tank according to claim 5, characterized in that the compartment (74) for settling and storage is provided with an upright pipe (76) whose first end is placed in the bottom of the settling chamber and whose opposite end extends in an upper end zone of said settling and storage compartment (74) and in that the water drawing means comprise a pipe (78) one end of which is placed in the vicinity of the venturi and the other end of which opens into the settling and storage compartment.  7. Tank according to one of claims 5 and 6, characterized in that the settling and storage compartment is provided with a drain tube (88), one end of which is placed in the bottom of said compartment (74) and of which the opposite end is connected to the fuel return tube via a valve distributor (90).  8. Tank according to claim 7, characterized in that the valve distributor comprises a first valve (92) placed on the fuel path to the reserve and a second valve (94) located downstream of the drain tube (88).  9. Tank according to any one of claims 1 to 8, characterized in that it comprises a fuel suction chamber (66) from which extends the filling duct (60), which chamber suction communicates with the decantation chamber via a passage located at a height adapted to avoid a passage of water from the decantation chamber to the suction chamber.  10. Tank according to any one of claims 1 to 9, characterized in that it comprises means for measuring the fuel level in the <Desc / Clms Page number 17>  tank (22; 57) and means for detecting the level of water in the container. he. Tank according to claim 10, characterized in that said measurement and detection means comprise a first float (46) arranged in the tank, a second float (48; 85) disposed in the settling chamber and / or in the storage compartment. decantation and storage, and a computer (50) associated with a variable resistance (52) whose resistance value varies as a function of the fuel level detected by the first float and comprising means for comparing the value of the variable resistance and a set of predetermined resistance values each corresponding to a fuel level in the tank, and in that it further comprises a switch for controlling the connection of an additional resistance (58) in series with the variable resistance, said switch being piloted by the second float so as to give the resistance a value which corresponds to a maximum level of water in the r container and so that the total value of the variable resistance varies depending on the water level in the container.  12. Tank according to claim II, characterized in that the variable resistance and the additional resistance are placed on a common support.  13. Tank according to one of claims 11 and 12, characterized in that the second float is associated with a magnet (49; 85) controlling the opening and closing of the control switch.  14. Tank according to any one of claims 1 to 13, characterized in that the container (22; 57) comprises means (96) for discharging the water present in the fuel contained in the container.  15. Tank according to claim 14, characterized in that the means for discharging the water comprise a tube (96) substantially parallel to the axis <Desc / Clms Page number 18> The present invention relates to a fuel tank for a motor vehicle of the type with integrated positive reserve. It also relates to a method of emptying such a tank.  Fuel tanks of this type conventionally comprise a proper tank, a container placed in the tank and in communication with the latter, fuel pumping means placed in the container and means for filling the container comprising a generally upright conduit in the container and a fuel return tube from the engine provided with a venturi opening into the container so as to cause a suction of fuel through the conduit.  The container filling means are effective in maintaining a sufficient level of fuel in the container, even when the tank contains little fuel.  However, the bottom of the tank is often filled with a certain amount of water caused by condensation phenomena. Consequently, the venturi, which causes a suction from the bottom of the tank leads, into the container, all the stagnant water in the bottom of the tank as well as all the pollutants in suspension and heavier than the fuel.  The presence of water in the bottom of the tank and in the bottom of the container is a major drawback due to the very high exhaustion capacity of this type of tank. In fact, practically all the water contained in the tank is sent to the engine.  This water oxidizes the metal parts. In addition, it forms oxides which return to the reservoir and risk strongly altering the constituent elements of the pumping members which are associated with it.  The object of the invention is to overcome this drawback.