GB2510054A

GB2510054A - Liquid fuel tank with motorised actuated horizontal baffle

Info

Publication number: GB2510054A
Application number: GB1321762.5A
Authority: GB
Inventors: Harish Viswanathan
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2013-12-10
Filing date: 2013-12-10
Publication date: 2014-07-23
Also published as: GB201321762D0

Abstract

A liquid fuel tank 1 for a motor vehicle, the tank comprising a baffle device 2 having a movable baffle 3 for damping slosh loads of the fuel 6, a venting device 7 comprising a vent valve 8 and a roll over valve 9, and a fuel delivery module 10 providing fuel to the engine. The baffle device 2 comprises an actuator 11, which moved the baffle 3 up or down, towards and away from a bottom 14 of the liquid fuel tank 1 in dependence on the fuel level in the tank. There may be a fuel detector 17 to determine the fuel level in the tank and cause the baffle to be moved to lie just above the level of the fuel. The baffle may move by means of telescopic bars 19. The invention also relates to a method for operating a liquid fuel tank 1 having a movable baffle.

Description

Liquid Fuel Tank The invention relates to a liquid fuel tank for a motor vehicle according to the preamble of claim 1. The invention also relates to a method for operating a liquid fuel tank for a motor vehicle according to the preamble of claim 5.

Such a liquid fuel tank can for example already be taken as known from US 20090078705. The liquid fuel tank there comprises a tank and an absorber assembly wherein the tank has an inner surface defining a cavity for receiving a liquid substance.

The absorber assembly is disposed within the cavity for dampening liquid sloshing noises.

The absorber assembly includes a plurality of connected dampener elements. End sections of the absorber assembly are attached to the inner surface of the tank. The absorber assembly is configured to float on a surface of the liquid when a volume of liquid within the tank is between a first critical volume and a second, lower critical volume. The absorber assembly is generally submerged when a volume of liquid within the tank is generally greater than the first critical volume. The absorber assembly is generally suspended within the cavity when a volume of liquid within the tank is generally lower than the second critical volume. Since the end sections of the absorber assembly are attached to the inner surface of the tank, the absorber assembly is bent due to the buoyancy of the connected dampener elements and thus in dependency on the fuel level of the liquid substance the liquid sloshing noises can be dampened by the absorber assembly only for certain fuel levels of the liquid substance.

It is the object of the present invention to provide a liquid fuel tank of the initially mentioned kind, by means of which sloshing effects of the fuel can be dampened at any fuel level of the fuel contained in the liquid fuel tank.

According to the invention, this object is solved by a liquid fuel tank having the features of claim 1 and by a method having the features of claim 5. Advantageous configurations with convenient developments of the invention are specified in the remaining claims.

In order to provide a liquid fuel tank of the initially mentioned kind, by means of which the sloshing of the fuel within the liquid fuel tank can be prevented for any possible fuel level in the liquid fuel tank, it is provided according to the invention that the baffle device comprises at least one actuator, by means of which the at least one baffle is both movable towards and away from a bottom of the liquid fuel tank. In other words, the baffle can be moved in such a manner that a certain distance between the waterline of the fuel and the baffle can be adjusted. In doing so it is both possible to immerse the baffle in the fuel or to keep the baffle out of the fuel. If the baffle is kept out of the fuel and the liquid fuel tank is accelerated and decelerated due to the motion of the motor vehicle the fuel can start to slosh and thus sloshing waves can touch the baffle in dependency on the distance between the baffle and the waterline of the fuel and the intensity of the fuel wave. As soon as the sloshing waves touch the baffle, the kinetic energy of the waves is at least substantially dissipated by means of the baffle and thus a free surface wave formation is prevented and the liquid fuel tank is at least substantially free from noise issues. Since the kinetic energy of the fuel waves is dissipated, slamming loads of the fuel that hit the walls of the liquid fuel tank are mitigated in an especially effective manner.

Therefore, the liquid load hitting the liquid fuel tank walls is minimized and almost negligible. By preventing the wave formation within the liquid fuel tank, a vapour generation can be prevented, if the fuel corresponds to gasoline or foaming and waxing is prevented, if the fuel corresponds to diesel oil. As an additional effect the venting performance of the liquid fuel tank can be enhanced in an especially easy manner due to the fact that any vapour pockets are arrested with clear gas/fuel phase distinction. Also the blockage of any vent valves can be avoided, since no fuel waves hit the vent valves and thus no blocking of the vent valves occurs and their performance can be maintained.

Further advantages, features and details of the invention are apparent from the following description of a preferred embodiment as well as based on the drawings.

They show in: Fig. 1 a schematic isometric view of a liquid fuel tank according to the invention wherein a baffle device is arranged within the liquid fuel tank and a baffle of the baffle device can be moved upwards and downwards by means of actuators; Fig. 2a a schematic isometric view of the position of the baffle when the fuel level is high; Fig. 2b a schematic isometric view of the position of the baffle when the fuel level is medium; Fig. 2c a schematic isometric view of the position of the baffle when the fuel level is low; and in Fig. 3 a flow chart describing a method for operating the liquid fuel tank and thus the movement of the baffle in dependency on the fuel level.

Fig. 1 shows a schematic isometric view of a liquid fuel tank 1 of a motor vehicle, wherein the motor vehicle is not shown here. The liquid fuel tank 1 is restricted by four side walls 16, presently a bottom 14, and a top 15. In other words, the liquid fuel tank 1 is presently designed as a cuboid and thus shown in a simplified manner, but the liquid fuel tank 1 could also comprise an arbitrary free-form surface. The liquid fuel tank 1 also comprises a venting device 7 with a vent valve 8 and several roll over valves 9. By means of the venting device 7 the liquid fuel tank 1 can be depressurized and vented, wherein fuel vapour is passed through an activated carbon filter which is not shown here. By means of the roll over valves 9 the fuel 6, which is contained in the liquid fuel tank 1 can be prevented from leaking if the liquid fuel tank 1 is turned over when e.g. the motor vehicle is rolling over in case of an accident. The liquid fuel tank 1 also comprises a fuel delivery module (FDM) 10, which is arranged at the bottom 14 and which is designed for completely emptying the liquid fuel tank 1 and thus providing a combustion engine of the motor vehicle with all of the available fuel 6. In other words, by means of the fuel delivery module 10, the liquid fuel tank 1 can be completely emptied. By means of a fuel line 5 the FDM 10 is connected with the combustion engine of the motor vehicle.

According to the invention, the liquid fuel tank 1 also comprises a baffle device 2 comprising a baffle 3 for damping slosh loads of the fuel 6. The baffle device 2 presently also comprises four actuators 11, by means of which the baffle 3 is both movable towards and away from the bottom 14 of the liquid fuel tank 1. The baffle 3 is held by a baffle frame 4, wherein the baffle frame 4 stabilizes the baffle 3. The liquid fuel tank 1 in Fig. 1 is shown as a cuboid and thus illustrated in an especially simplified manner. It is clear that usually a liquid fuel tank 1, which is used in a motor vehicle comprises a lot of free form contours and thus is usually not symmetrical. To avoid a collision of the baffle frame 4 with the side walls 16 of the liquid fuel tank 1, the baffle frame 4 is arranged in such a manner within the liquid fuel tank 1 that the baffle frame 4 cannot be jammed at the side walls 16 when the baffle device 2 is moved in either an upward direction 12 or a downward direction 13 by means of the actuators 11. In order to achieve this, the baffle frame 4 is spaced from the side walls 16 in such a manner that the baffle frame 4 does not collide with the side walls 16 when the baffle device 2 is moved towards and away from the bottom 14 or in other words moved according to the downward direction 13 or the upward direction 12. The actuators 11, which are designed as linear electric motors are each engaging a telescopic bar 19 wherein the telescopic bars 19 are arranged perpendicularly to the bottom 14 and their bearing points on the bottom 14 are arranged in such a manner, that they form the corners of an imaginary rectangle on the bottom 14.

In doing so, each telescopic bar 19 is arranged close to a corner of the liquid fuel tank 1, wherein each of the corners of the liquid fuel tank 1 is built by two of the side walls 16 at present.

The baffle 3 comprises a reticular structure 20, which can both be rigid or elastic. If the reticular structure 20 of the baffle 3 is rigid, then the baffle frame 4 can be dispensed with.

If the reticular structure 20 and thus the baffle 3 is elastic, then the baffle 3 has to be held by the baffle frame 4, in order to prevent sagging of the baffle 3. In the center of the baffle 3 a fuel level detector (ELD) 17 is arranged. By means of this fuel level detector 17 a fuel level 18 (the waterline) of the fuel 6 can be detected. To avoid sloshing effects of the fuel 6, e.g. when the motor vehicle is accelerating or decelerating, the baffle 3 is moved correspondingly to the upwards direction 12 or the downwards direction 13 by means of the actuators 11 in dependency on the fuel level 18 of the liquid fuel tank 1. In other words the telescopic bars 19, which are connected with the baffle 3 are moved by the actuators 11 in dependency on the fuel level 18, which is detected by the FLD 17. The baffle 3 is moved between two motion limits hmax, wherein hmax corresponds to the topmost position of the baffle 3 within the liquid fuel tank 1 and thus the maximum distance between the baffle 3 and the bottom 14 of the liquid fuel tank 1. The FDM lOis arranged at the bottom 14 of the liquid fuel tank 1 and extends to a height that corresponds to about 7 to 10% of the fuel level 18. The motion limit hmjn corresponds to a distance between the baffle 3 and the bottom 14, in which a collision between the baffle 3 and the FDM 10 is avoided. In other words, the motion limit of the baffle 3 corresponds to a distance between the baffle 3 and the bottom 14, which corresponds to a fuel level 18 of more than 10 %. Since slosh loads are predominant only between a 100 % to 30 % of the fuel level 18, slosh effects can be prevented especially reliably by moving the baffle 3 between hmin and hmax.

Fig. 2a to Fig. 2c illustrate the different positions of the baffle 3, which is moved by means of the actuators 11. In Fig. 2a the baffle 3 is arranged at the motion limit hmax in Fig. 2b.

The baffle 3 is arranged between hmin and hmax and in Fig. 2cthe baffle is arranged at the motion limit Fig. 3 shows a flow chart, by means of which the movement of the baffle 3 of the baffle device 2 in dependency on the fuel level 18 shall be explained in the following: The method starts with the plan to adjust the baffle 3 to the fuel level 18 of the fuel 6 within the liquid fuel tank 1. Hence at first the fuel level 18 has to be detected by means of the FLD 17 (detect fuel level 18 in liquid fuel tank 1"). Afterwards the baffle 3 is positioned in a distance of about 2 mm above the free surface level (fuel level 18) of the fuel 6 by moving through the actuators 11 ("position the baffle 3 at 2 mm above free surface level of fuel 6 -by moving it"). Subsequently two different queries are carried out. One of the queries is "is the fuel's 6 free surface height = hmin?". If this state is not reached ("no"), the method continues with the step "detect fuel level 18 in liquid fuel tank 1". If the liquid fuel tank 1 is almost empty and thus the fuel's 6 free surface height has reached the value (yes"), the baffle 3 is positioned at the motion limit hmin by means of the actuators 11.

The other query is if refuelling takes place or if the filler cap is in an open position ("is refuelling taking place/filler cap in open position?"). If this state is not given ("no"), the method continues with the step "detect fuel level 18 in liquid fuel tank 1. If the state is given ("yes"), the step "position baffle 3 at height hm" follows. Afterwards, another query ("has refuelling been completed?") is checked. If the refuelling has not been completed yet ("no"), the method continues with the step "position baffle 3 at height hmax". If the refuelling has been completed (yes"), the method of moving the baffle 3 in dependency on the fuel level 18 continues with the steps "detect fuel level 18 in liquid fuel tank 1" followed by "position the baffle 3 at 2 mm above free surface level of fuel 6 -by moving it".

List of reference signs 1 liquid fuel tank 2 baffle device 3 baffle 4 baffle frame fuel line 6 fuel 7 venting device S vent valve 9 roll over valve fuel delivery module (FDM) 11 actuator 12 upward direction 13 downward direction 14 bottom top 16 sidewall 17 fuel level detector (FLD) 18 fuel level 19 telescopic bar reticular structure hmin, hmax motion limit

Claims

Claims A liquid fuel tank (1) for a motor vehicle, the liquid fuel tank (1) comprising -a baffle device (2) comprising at least one baffle (3) for damping slosh loads of the fuel (6), -a venting device (7) comprising at least one vent valve (8) and at least one roll over valve (9) and -a fuel delivery module (10) for providing a combustion engine of the motor vehicle with fuel (6) characterized by the baffle device (2) comprising at least one actuator (11) by means of which the at least one baffle (3) is both movable towards and away from a bottom (14) of the liquid fuel tank (1).
2. The liquid fuel tank (1) according to claim 1 characterized in that the baffle device (2) comprises a fuel level detector (17), by means of which the baffle (3) is movable in dependency on a fuel level (18).
3. The liquid fuel tank (1) according to claim 1 or 2 characterized in that the baffle device (2) comprises at least one telescopic bar (19), by means of which the baffle (3) is movable.
4. The liquid fuel tank (1) according to any one of the claims 1 to 3 characterized in that the baffle (3) at least partially comprises a reticular structure (20).
5. A method for operating a liquid fuel tank (1) for a motor vehicle, the liquid fuel tank (1) including -a baffle device (2) comprising at least one baffle (3) for damping slosh loads of the fuel (6) -a venting device (7) comprising at least one vent valve (8) and at least one roll over valve (9) and -a fuel delivery module (10) for providing a combustion engine of the motor vehicle with fuel (6) characterized by the at least one baffle (3) is moved by means of at least one actuator (11) towards and away from a bottom (14) of the liquid fuel tank in dependency on a fuel level (18) of the liquid fuel tank (1).