TANK WITH PIPE PREVENTING LIQUID FUEL FROM FLYING TO A FUEL VAPOR STORAGE DEVICE

Abstract

The invention relates to a fuel tank (1) delimited by an outer casing, one face of which, intended to be an upper face (1a) in the mounted position of the fuel tank (1) in a motor vehicle, carries at least one ventilation valve (2, 2a) connected to a ventilation duct (3) evacuating fuel vapors exiting the tank (1) through said at least one ventilation valve (2, 2a) intended for a device (4) for storing and treating fuel vapors, characterized in that the tank (1) comprises a protective duct (5, 5a) having an inlet end connected to said at least one valve (2, 2a) and an outlet end connected to an inlet of the ventilation duct (3), a portion of the protective duct (5, 5a) having means for preventing the passage of liquid fuel towards the ventilation duct (3).

Description

[0001] The present invention relates to a tank with a conduit preventing the passage of liquid fuel to a fuel vapor storage and treatment device.

[0002] Generally, according to the state of the art, a fuel tank is delimited by an external casing, one face of which, intended to be a top face in the mounted position of the fuel tank in a motor vehicle, carries at least one ventilation flap connected directly to a ventilation pipe leading fuel vapors exiting the tank through said at least one ventilation flap into a fuel vapor storage and treatment device.

[0003] Fuel tanks are therefore equipped with one or more vent valves. These vent valves allow the tank to breathe. They allow the gasoline vapors stored in the tank to be vented to a fuel vapor storage and treatment device, also known as a canister.

[0004] Ventilation valves also serve to regulate the internal pressure of the tank containing vapors, regardless of static operating conditions, such as inclines or slopes, or dynamic operating conditions of the motor vehicle. However, ventilation valves must not allow liquid fuel to escape. Indeed, if liquid fuel were to pass through the valves, it would end up in the fuel vapor storage and treatment system, and such a system is not designed to store or treat liquid fuel.

[0005] If the fuel vapor storage and treatment device recovers liquid fuel, then the engine will no longer function correctly, and in extreme cases, when the device is completely saturated with fuel, the fuel will overflow through its vent and this will generate nothing less than a fuel leak, which is obviously prohibited.

[0006] There is a wide variety of vent valves available. These vent valves vary in performance and may not all function correctly on certain tank designs, which are therefore more or less susceptible to the problem. To protect a fuel vapor storage and treatment system from the potential introduction of liquid fuel that could pass through the vent valve(s), several technical solutions are possible.

[0007] To illustrate one of these solutions, the basic approach involves moving the fuel vapor storage and treatment unit to a higher position within the vehicle. This way, by gravity, the liquid fuel in the ventilation duct that feeds the fuel vapor storage and treatment unit would return to the tank because it would not reach the unit, which would then be located at a higher elevation.

[0008] However, fuel vapor storage and treatment systems are often located below fuel tanks and therefore below ventilation valves. In this configuration, sensitive or non-compliant valves could allow too much liquid fuel to pass through, ending up in the fuel vapor storage and treatment system below.

[0009] It is not possible to relocate the fuel vapor storage and treatment system in the vehicle to another location, particularly on vehicles already on the market or under development, as this type of modification is extremely complex and costly for the motor vehicle as a whole and for the manufacturing plants.

[0010] Existing fuel tanks are equipped with one or more vent pipes extending from one or more respective vent valves and leading directly to the fuel vapor storage and treatment system, without any means of preventing liquid fuel from entering the storage system. This is illustrated in particular by document EP-B1-0 997 336.

[0011] Therefore, the problem based on the present invention is, for a fuel tank comprising at least one vent valve connected to a vent pipe carrying fuel vapors to a fuel vapor storage and treatment device associated with the fuel tank, to prevent a leak of liquid fuel through the vent valve(s) and their associated pipe which would end in the fuel vapor storage and treatment device.

[0012] To achieve this objective, the invention provides a fuel tank delimited by an external casing, one face of which, intended to be an upper face in the mounted position of the fuel tank in a motor vehicle, carries at least one ventilation valve connected to a ventilation duct evacuating fuel vapors exiting the tank through said at least one ventilation valve intended for a fuel vapor storage and treatment device, characterized in that the tank includes a protective duct having an inlet end connected to said at least one valve and an outlet end connected to an inlet of the ventilation duct, a portion of the protective duct having means for preventing the passage of liquid fuel towards the ventilation duct.

[0013] The ventilation lines leading to the fuel vapor storage and treatment system are designed to carry only fuel vapors. However, in practice, with certain tank designs and some types of vent valves, liquid fuel may accompany the vapors passing through the valve.

[0014] Fuel tank architectures that have multiple valves or a single valve offset towards one end of the upper face of the casing will regularly be in contact with the fuel, and therefore the risk of fuel transfer to the fuel vapor storage and treatment device is increased for these architectures.

[0015] The invention presented here ingeniously circumvents this type of phenomenon, regardless of the type of valve, whether efficient or not, and regardless of the type of fuel tank, including its geometry, capacity, material, etc. This new ventilation architecture, equipped with a valve-controlled preventative duct upstream of the fuel vapor storage and treatment device, is designed to prevent the passage of liquid fuel, for example by having a portion that is high or raised relative to the liquid fuel level in the tank, thus preventing fuel from entering the fuel vapor storage and treatment device.

[0016] The solution of the present invention is all the more interesting as it is not technologically complicated, using only one or more protective pipes and not resorting to complex and costly technical devices to protect the fuel vapor storage and treatment device.

[0017] The present invention solves the problem of introducing liquid fuel into the fuel vapor storage and treatment system. The present invention also solves quality issues related to the operation of the internal combustion engine and fuel leaks outside the vehicle. Implementation of the present invention does not require the addition of new components or the maintenance of existing ventilation valves, regardless of their intrinsic performance. The solution presented in the present invention is adaptable and applicable to all gasoline fuel systems and is a non-intrusive solution within the vehicle, economical because it is less expensive compared to other, more intrusive solutions.

[0018] The solution proposed by the present invention may become a design reference in the future for any vehicle whose fuel vapor storage and treatment device cannot be relocated vertically.

[0019] In summary, the invention solves all the problems concerning the introduction of liquid fuel into the fuel vapor storage and treatment device, representing a significant technical advance.

[0020] Advantageously, the means of preventing the passage of liquid fuel towards the ventilation pipe are an elevated positioning of the portion referred to below as elevated of the protective pipe relative to the level of said at least one ventilation valve.

[0021] Advantageously, a height of the raised positioning is determined by experience, the height being sufficient so that the raised portion of the protective piping is above the level of said at least one ventilation valve under driving conditions of the motor vehicle on an inclined road or on a slope taking the upper face of the outer shell of the tank from a horizontal plane to an inclined plane with said at least one ventilation valve being in a portion then lowest of the upper face in the inclined plane.

[0022] The shape of the protective pipe(s) must ensure, in terms of configuration, route, and routing, that the protective pipe(s) have a section higher than the liquid fuel level in the tank. Indeed, if the tank tilts, the vent valve may be submerged in the fuel, and if the valve leaks or allows liquid fuel to pass into the protective pipe, then the liquid fuel will flow towards the fuel vapor storage and treatment system unless the protective pipe passes through a point higher than the liquid fuel level in the tank.

[0023] Advantageously, the raised portion forms a loop, an upstream branch of the protective pipe connected to the loop extending from said at least one ventilation valve towards the raised portion and a downstream branch of the protective pipe connected to the loop extending from the raised portion towards the ventilation pipe.

[0024] The invention consists of a new architecture for the protective piping of a fuel tank. The configuration and routing of the respective loop-shaped protective piping are defined to protect the fuel vapor storage and treatment device against the introduction of liquid fuel under all vehicle operating conditions.

[0025] Advantageously, the protective conduit for said at least one valve extends along the upper face of the fuel tank casing.

[0026] The advantage of a design where the protective piping remains located on the upper surface of the tank's outer casing is that it is not intrusive to other vehicle components and does not disrupt the vehicle's manufacturing processes at the factory. It is an effective, non-intrusive technical solution that can be applied to all gasoline fuel tanks when the fuel vapor storage and treatment system is not located high up in the vehicle.

[0027] Advantageously, at least one groove is cut on the upper face of the fuel tank casing for at least partial reception of the protective pipe.

[0028] Advantageously, said at least one groove has a part receiving at least partially simultaneously the protective conduit and the ventilation conduit.

[0029] Advantageously, at least one retaining bar is superimposed locally on the protective pipe, said at least one retaining bar extending from 60° to 120° relative to the protective pipe, the longitudinal ends of said at least one retaining bar having means for snapping into the upper face of the outer casing of the fuel tank.

[0030] The pipe support bar(s) on the tank casing are not an essential solution of the present invention but are purely optional. The use of a support bar or bars is primarily due to the difficulty of securing all the lines by snap-fitting them onto the casing using welded clips / spacers, because of the limited space available on a fuel tank according to the present invention.

[0031] Advantageously, the fuel tank has at least two vent valves, each vent valve having a respective protective duct, the two protective ducts having a connection point to open simultaneously into the vent duct.

[0032] Advantageously, said at least two ventilation valves are each disposed towards a respective longitudinal end of the upper face of the outer shell of the fuel tank, the two protective pipes extending in opposite directions towards the other longitudinal end of the shell opposite the longitudinal end bearing their associated ventilation valve, each protective pipe forming a loop at said other longitudinal end.

[0033] Other features, purposes, and advantages of the present invention will become apparent from the detailed description that follows and from the accompanying drawings, which are given by way of non-limiting examples and on which: THE figures 1 and 2 are schematic representations of an upper face of an external casing of a fuel tank comprising two ventilation valves and a ventilation duct as well as a valve protection duct against the passage of liquid fuel towards the ventilation duct intended to open onto a fuel vapor storage and treatment device, this according to two respective embodiments according to the present invention.

[0034] It should be borne in mind that the figures are given as examples and are not limiting to the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. In particular, the dimensions of the various elements illustrated are not representative of reality.

[0035] In what follows, reference is made to all figures taken in combination. When reference is made to one or more specific figures, that figure is to be taken in combination with the other figure for the recognition of the designated numerical references.

[0036] In what follows, the terms "vertically", "horizontally", "superior" and other references to spatial positioning are understood to refer to the components, primarily the fuel tank, positioned in their normal operating and usage position, particularly in a motor vehicle arranged on a horizontal plane.

[0037] By referring to figures 1 and 2 which show two alternative embodiments of the gasoline fuel tank 1 according to the present invention, the invention relates to a fuel tank 1 delimited by an outer casing. One face of the outer casing is intended to be an upper face 1a in the mounted position of the fuel tank 1 in a motor vehicle and will be referred to hereafter as upper face 1a.

[0038] The upper face 1a has at least one ventilation valve 2, 2a connected, directly according to the prior art and indirectly according to the present invention, to a ventilation duct 3 evacuating fuel vapors exiting the tank 1 through said at least one ventilation valve 2, 2a intended for a fuel vapor storage and treatment device 4, illustrated very schematically in the figures, the ventilation duct 3 not being shown connected to the fuel vapor storage and treatment device 4, as this ventilation duct 3 should be.

[0039] To figures 1 and 2 , two ventilation flaps 2, 2a are shown, each located towards one longitudinal end of the upper face 1a of the envelope, being substantially diagonally opposite if the upper face 1a is considered to have a roughly rectangular shape.

[0040] According to the invention, in contrast to the prior art which connected the ventilation duct 3 directly to an associated ventilation damper 2, 2a, the tank 1 includes a protective duct 5, 5a for each ventilation damper 2, 2a. This protective duct 5, 5a has an inlet end connected to the associated damper 2, 2a and an outlet end connected to an inlet of the ventilation duct 3.

[0041] This protective pipe 5, 5a is therefore inserted between the damper 2, 2a or each damper 2, 2a and a ventilation pipe 3 which may be common to several protective pipes 5, 5a. It is evident that there is one protective pipe 5, 5a for each ventilation damper 2, 2a, therefore two protective pipes 5, 5a when there are two damper 2, 2a and so on.

[0042] A portion 6, 6a of the protective pipeline 5, 5a incorporates means for preventing the flow of liquid fuel into the ventilation pipeline 3. These means may consist of a sharp rise in the pipeline 5, 5a, with an upstream section located below a downstream section. The liquid fuel is stopped by the sharp rise and stagnates in the upstream section. However, it is preferable that the prevention means be effective by using gravity.

[0043] In the preferred embodiment of the prohibition means, the means for preventing the passage of liquid fuel towards the ventilation pipe 3 can be created by an elevated positioning of the portion referred to below as elevated of the protective pipe 5, 5a relative to the level of said at least one ventilation valve 2, 2a.

[0044] It is necessary to choose a raised section that can counteract upward movements of the ventilation flap(s) 2, 2a due to vehicle movement and driving conditions, for example the slope and camber of the road.

[0045] The protection provided by the present invention is primarily intended to address leaks in static conditions, for example, for a vehicle parked on a slope or on a sidewalk, because under these conditions the valve remains constantly immersed in fuel. In practice, under dynamic conditions, the valves may behave differently and may not present any particular problems, except for valves sensitive to dynamic conditions.

[0046] Therefore, a height for the raised positioning can be determined experimentally. The height may be sufficient so that the raised portion 6, 6a of the protective duct 5, 5a is above the level of at least one ventilation valve 2, 2a under conditions of driving the motor vehicle on an inclined or sloped road.

[0047] Such rolling can cause the upper surface 1a of the outer casing of the tank 1 to move from a horizontal plane, which it occupies when the vehicle is traveling on a horizontal plane, to an inclined plane under conditions of slope and camber. In this case, the ventilation valve(s) 2, 2a may be located in the lowest portion of the upper surface 1a on the inclined plane.

[0048] On the contrary, in the case of at least one ventilation flap 2, 2a disposed towards one longitudinal end and at least one ventilation flap 2, 2a disposed towards the other longitudinal end of the upper face 1a, one of the two flaps 2, 2a will then be in a lowered position while the other will be in a raised position.

[0049] As shown to figures 1 and 2 The raised portion of the protective pipe 5, 5a can form a loop 6, 6a. An upstream branch of the protective pipe 5, 5a can then be connected to the loop 6, 6a by extending from at least one ventilation valve 2, 2a to the raised portion 6, 6a. A downstream branch of the protective pipe 5, 5a can then be connected to the loop 6, 6a by extending from the raised portion forming the loop 6, 6a to the ventilation pipe 3.

[0050] Always, as shown to the figures 1 and 2The protective pipe 5, 5a of the valve 2, 2a, or the protective pipes associated with a respective valve 2, 2a, may extend along the upper face 1a of the fuel tank 1 casing. This is preferred for the support and protection of the pipes, but is not a limitation.

[0051] For example, another embodiment involves extending one or more protective pipes higher in the vehicle, leaving contact with the upper face 1a of the casing. This is technically just as valid as for one or more protective pipes associated with a respective valve 2, 2a extending along the upper face 1a of the casing, but more complex to industrialize.

[0052] The protective pipe(s) 5, 5a can therefore rise more or less vertically above the upper face 1a and return to it, forming a bend at their highest point, furthest from the upper face 1a of the casing. This is not shown in the figures, but the references to the figures 1 and 2 .

[0053] To figures 1 and 2 , two ventilation valves 2, 2a are shown and a protective conduit 5, 5a associated with each valve, therefore two protective conduits 5, 5a extending when applied against the upper face 1a of the fuel tank 1 shell.

[0054] While valid for a different number of ventilation valves 2, 2a and protective conduit 5, 5a, at least one groove may be cut on the upper face 1a of the fuel tank casing 1 for at least partial reception of the protective conduit 5, 5a.

[0055] As can be seen at the figure 2 , at least one groove may have a part receiving at least partially simultaneously the two protective pipes 5, 5a, including a protective pipe 5 on both its return branch and its supply branch and the ventilation pipe 3.

[0056] To the figure 2 , part of the furrow receives the upstream and downstream branches going to and from a first loop 6 of a first protective pipe 5 coming from the first ventilation valve 2 as well as the upstream branch of a second protective pipe 5a coming from the second ventilation valve 2a and also the ventilation pipe 3 opening onto the device 4 for storing and treating fuel vapors.

[0057] By referring to the figure 2, at least one support bar 7, in this figure four support bars 7, may be superimposed locally at least on the protection pipe(s) 5, 8a and possibly on the ventilation pipe 3 for some of the bars 7, the support bar(s) 7 extending from 60° to 120° relative to the protection pipe(s) while remaining in a superimposed plane and parallel to the plane containing the protection pipe(s) 5, 5a at the level of each support bar 7.

[0058] The longitudinal ends of the retaining bar(s) 7 may have means for snapping into the upper face 1a of the outer casing of the fuel tank 1. figure 1 , only one support bar 7 is shown.

[0059] As shown to figures 1 and 2The fuel tank 1 may have at least two ventilation valves 2, 2a. Each ventilation valve 2, 2a may have a respective protective conduit 5, 5a, the two protective conduits 5, 5a having a connection point 8 to open simultaneously into the ventilation conduit 3.

[0060] To figures 1 and 2 A fuel tank 1 is shown equipped with two ventilation valves 2, 2a. Other fuel tanks 1 may be equipped with more or fewer valves 2, 2a, the present invention being applicable to any number of valves 2, 2a.

[0061] By referring to figures 1 and 2If tank 1 tilts to the left, then the left ventilation valve 2 or first valve 2 will be immersed and submerged in the liquid fuel contained in tank 1. Therefore, it is necessary that the first protective pipe 5 associated with the first valve 2 go in the opposite direction towards the second valve 2a to rise in level.

[0062] The ultimate goal is that the overall protection and ventilation architecture of tank 1 allows, under all conditions, for valves 2, 2a equipped with protection pipes 5, 5a to be higher than the level of liquid fuel in tank 1. The two protection pipes 5, 5a join at a connection point 8 from which a ventilation pipe 3 leads to the fuel vapor storage and treatment device 4.

[0063] This ventilation duct 3 has no more function than the ventilation ducts existing today and provides the link with the fuel vapor storage and treatment device 4.

[0064] At the outlet of the ventilation dampers 2, 2a, the protective pipes 5, 5a can either be press-fitted onto the outlets of the dampers 2, 2a using a suitable process. In this case, these protective pipes 5, 5a cannot be removed, making them less expensive to manufacture. Alternatively, these pipes can be snapped onto the associated ventilation damper 2, 2a using a snap-fit ​​mechanism, which is a more expensive but removable solution.

[0065] The at least two ventilation valves 2, 2a may each be disposed towards a respective longitudinal end of the upper face 1a of the outer casing of the fuel tank 1. The two protective pipes 5, 5a may extend at least partially in opposite directions towards the other longitudinal end of the casing opposite the longitudinal end bearing their associated ventilation valve 2, 2a, each protective pipe 5, 5a forming a loop 6, 6a at said other longitudinal end.

[0066] It should be noted that there are not only tank 1 designs with valves 2, 2a welded to the outside of the casing, as shown in the figures. There may also be fuel tanks 1 with valves 2, 2a welded and / or assembled inside the casing, particularly for systems designed to meet the most stringent standards. However, the present invention also covers these versions, being valid for any type of gasoline fuel tank 1, regardless of its manufacturing process.

[0067] Other technical solutions can address the problem of unwanted liquid fuel entering the fuel vapor storage and treatment device 4. If the vehicle is designed to allow the fuel vapor storage and treatment device 4 to be located higher than the fuel tank 1 and its vent valve(s) 2, 2a, then the risk is low.

[0068] Another technical solution would be to add a liquid-vapor separation box between the ventilation valves and the fuel vapor storage and treatment device. This box would serve to store the fuel that passes through the valves, and this fuel would then be redirected back to the tank and not to the fuel vapor storage and treatment device. This technical solution, however, has significant limitations and constraints but could also address the problem underlying the present invention.

[0069] The invention is in no way limited to the embodiments described and illustrated, which have been given only by way of example.

Claims

1. Fuel tank (1) delimited by an outer casing, one face of which, intended to be an upper face (1a) in the mounted position of the fuel tank (1) in a motor vehicle, carries at least one ventilation valve (2, 2a) connected to a ventilation duct (3) evacuating fuel vapors exiting the tank (1) through said at least one ventilation valve (2, 2a) intended for a device (4) for storing and treating fuel vapors, characterized in that the tank (1) includes a protective pipe (5, 5a) having an inlet end connected to said at least one valve (2, 2a) and an outlet end connected to an inlet of the vent pipe (3), a portion (6, 6a) of the protective pipe (5, 5a) having means for preventing the passage of liquid fuel into the vent pipe (3).

2. Tank (1) according to the preceding claim, in which the means for preventing the passage of liquid fuel towards the ventilation pipe (3) are an elevated positioning of the portion referred to below as elevated (6, 6a) of protective pipe (5, 5a) relative to the level of said at least one ventilation valve (2, 2a).

3. Tank (1) according to the preceding claim, in which a height of the raised positioning is determined experimentally, the height being sufficient so that the raised portion (6, 6a) of protective piping (5, 5a) is above the level of said at least one ventilation valve (2, 2a) under driving conditions of the motor vehicle on an inclined or sloped road causing the upper face (1a) of the outer casing of the tank (1) to pass from a horizontal plane to an inclined plane with said at least one ventilation valve (2, 2a) being in a portion then lowest of the upper face (1a) in the inclined plane.

4. Tank (1) according to any one of claims 2 or 3, wherein the raised portion forms a loop (6, 6a), an upstream branch of the protective pipe (5, 5a) connected to the loop (6, 6a) extending from said at least one ventilation valve (2, 2a) to the raised portion (6, 6a) and a downstream branch of the protective pipe (5, 5a) connected to the loop (6, 6a) extending from the raised portion (6, 6a) to the ventilation pipe (3).

5. Tank (1) according to any one of the claims, in which the protective conduit (5, 5a) of said at least one valve (2, 2a) extends along the upper face (1a) of the fuel tank (1) casing.

6. Tank (1) according to the preceding claim, in which at least one groove is cut on the upper face (1a) of the fuel tank (1) casing for at least partial reception of the protective conduit (5, 5a).

7. Tank (1) according to the preceding claim, in which said at least one groove has a part receiving at least partially simultaneously the protective conduit (5, 5a) and the ventilation conduit (3).

8. Tank (1) according to any one of the three preceding claims, in which at least one retaining bar (7) is locally superimposed on the protective conduit (5, 5a), said at least one retaining bar (7) extending from 60° to 120° relative to the protective conduit (5, 5a), the longitudinal ends of said at least one retaining bar (7) having means for snapping into the upper face (1a) of the outer shell of the fuel tank (1).

9. Tank (1) according to any one of the preceding claims, wherein the fuel tank (1) has at least two ventilation valves (2, 2a), each ventilation valve (2, 2a) having a respective protective conduit (5, 5a), the two protective conduits (5, 5a) having a connection point (8) to open simultaneously into the ventilation conduit (3).

10. Tank (1) according to the preceding claim, in which said at least two ventilation valves (2, 2a) are each disposed towards a respective longitudinal end of the upper face (1a) of the outer shell of the fuel tank (1), the two protective pipes (5, 5a) extending in opposite directions towards the other longitudinal end of the shell opposite the longitudinal end bearing their associated ventilation valve (2, 2a), each protective pipe (5, 5a) forming a loop (6, 6a) at said other longitudinal end.