Bladder-equipped vehicle fuel storage system

Abstract

The vehicle fuel storage system (2) includes a fuel tank (4), at least one expandable bladder (6) extending within the tank (4), and at least one thermal storage reservoir (10) extending within the tank (4), the thermal storage reservoir (10) including a phase change material (12) having a melting point between 18°C ​​and 40°C.

Description

[Technical Field]

[0001] The present invention relates to a fuel tank for a vehicle, and more particularly to a fuel storage system for a vehicle. [Background technology]

[0002] Fuel stored in vehicle fuel tanks is subject to temperature fluctuations, primarily dependent on the ambient air temperature. Depending on the climate in which the vehicle is placed, the temperature of the fuel can vary significantly, especially if the vehicle is outdoors, whether in motion or parked. The increase in temperature of fuel stored in the tank will result in a certain amount of fuel evaporation. Because the tank defines a closed volume, the generation of fuel vapor will result in a pressure increase in the gas phase within the tank. The high pressure of the fuel vapor will cause mechanical stresses on the tank walls, and if the pressure increase is not controlled, it may damage the tank walls or otherwise pose a risk of tank explosion.

[0003] The prior art, for example from document WO 2021 / 013940 A1, is known for arranging an inflatable bladder inside a fuel tank. This bladder is connected to an air inlet / outlet pipe leading from the fuel tank, which allows for alternately supplying air to the bladder and evacuating a portion of the air contained in the bladder. The bladder can then expand and contract in order to vary the volume available for fuel vapors depending on the fluctuations in the amount of fuel vapor in the tank, thereby reducing changes in fuel vapor pressure. Reference can also be made to document DE 10 2018 203006 A1, which discloses a fuel storage system for vehicles in the preamble of claim 1.

[0004] While this bladder system certainly reduces the risk of experiencing pressure peaks in the fuel tank, it does present several problems. Indeed, the volume of the bladder inside the fuel tank constitutes volume unavailable for fuel, and therefore the presence of the bladder limits the tank's effective capacity. For example, for a 45-liter fuel tank, the bladder would need to have a volume of approximately 20 liters to be significantly effective, thereby nearly halving the tank's effective volume. Furthermore, the bladder's large volume complicates the process of inserting the bladder into the tank during manufacturing, increasing the cost and time of the tank's construction. Furthermore, the presence of the bladder inside the tank introduces biases that can mislead the measurement of the fuel level in the tank. These biases stem from the uncertainty surrounding the shape of the bladder, especially when the bladder is only partially inflated. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO 2021 / 013940 A1 [Patent Document 2] DE 10 2018 203006 A1 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention specifically addresses the problems identified in the prior art by reducing the buildup of fuel vapor pressure within the tank and avoiding or mitigating the disadvantages caused by the prior art bladders and their large volume. [Means for solving the problem]

[0007] Therefore, the present invention provides - a fuel tank; - at least one inflatable bladder extending inside the tank; - at least one heat accumulator extending inside the tank, the heat accumulator containing a phase change material with a melting point between 18°C ​​and 40°C; The present invention relates to a vehicle fuel storage system comprising:

[0008] The at least one heat accumulator is capable of absorbing heat, especially when the fuel is at a temperature close to the melting point of the phase change material. Indeed, since the melting reaction is endothermic, the heat of the fuel is consumed during the melting reaction. Therefore, the at least one heat accumulator reduces the temperature rise of the fuel, thereby reducing the generation of fuel vapor in the tank. This reduced generation of fuel vapor allows the bladder to be designed with a smaller volume, thereby reducing the disadvantages associated with the bladder volume, namely, the limitations on the tank's usable volume, the uncertainty of fuel level measurement, and the complexity of inserting the bladder into the tank during tank manufacturing. Thus, it can be seen that the combined effect of the at least one heat accumulator and the bladder exceeds the effects obtained when the at least one heat accumulator and the bladder are considered individually.

[0009] Testing also showed that the use of thermal accumulators is more effective at reducing fuel vapor pressure rise in small fuel tanks, while bladders are more effective at reducing fuel vapor pressure rise in large fuel tanks. The combination of these two technologies provides a consistent level of effectiveness in reducing fuel vapor pressure rise regardless of tank volume.

[0010] According to a first embodiment of the invention, the at least one heat accumulator is fixed to the bottom wall of the tank.

[0011] The at least one heat accumulator is therefore immersed in fuel for as long as the tank contains fuel, thereby ensuring that the at least one heat accumulator remains in thermal contact with the fuel at all times.

[0012] According to a second embodiment of the present invention, the at least one heat accumulator is fixed to the at least one bladder.

[0013] The at least one thermal accumulator then applies a load to the bladder wall, which makes it easier to open when it fills with air. It also helps break up fuel waves as they move within the tank when the vehicle is moving, giving the bladder a so-called "anti-slosh" or wave-damping function.

[0014] According to a third embodiment of the invention, the at least one heat accumulator is made in the form of a float adapted to float on the fuel in the tank.

[0015] The at least one heat accumulator is then manufactured in the form of a float, so that it is clear that no fixing steps for fixing the heat accumulator in the tank are necessary, which makes it easier to manufacture the fuel storage system, and furthermore, the at least one heat accumulator is always in thermal contact with the fuel.

[0016] Advantageously, the fuel storage system comprises a plurality of heat accumulators.

[0017] This increases the heat absorption capacity of the heat accumulator from the fuel. Also, the heat accumulator can be placed at various positions in the tank, which makes it possible to homogenize the heat exchange between the fuel and the heat accumulator, thereby homogenizing the fuel temperature. This also contributes to suppressing the generation of fuel vapor in the tank.

[0018] Preferably, the heat accumulator is fixed to a support plate arranged to float on the fuel in the tank. Preferably, the support plate is equipped with floats.

[0019] The plates allow the heat accumulators to be kept in a constant overall configuration within the interior space of the tank, thereby preventing all the heat accumulators from gathering locally within the tank, i.e. the plates allow the heat accumulators to be properly distributed within the volume of the tank.

[0020] Advantageously, the phase change material has a melting point of between 20°C and 30°C.

[0021] Therefore, the melting point is at a temperature that the fuel normally reaches, and the heat storage device can effectively suppress the temperature rise of the fuel when the phase change material melts.

[0022] Advantageously, the phase change material is calcium chloride hexahydrate (CaCl2.6H2O), octadecane (C 18 H 38 ), cyclohexanol (CH 12 O), selected from the list of glycerin derivatives.

[0023] These materials have melting points near 25°C, which makes them particularly suitable for the present invention.

[0024] Advantageously, the energy storage system comprises a plurality of thermal accumulators, which are fixed to the bottom wall of the tank and / or fixed to at least one bladder and / or made in the form of floats configured to float on the fuel in the tank.

[0025] In this way, by combining the three embodiments, the heat accumulator can be placed in various locations within the tank, and therefore the present invention can be adapted to tanks of various configurations.

[0026] The invention will be better understood on reading the following description, given by way of example only and with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0027] [Figure 1]1 is a schematic diagram of a vehicle fuel storage system according to a first embodiment of the present invention. [Figure 2] FIG. 4 is a schematic diagram of a vehicle fuel storage system according to a second embodiment of the present invention. [Figure 3] FIG. 4 is a schematic diagram of a fuel storage system for a vehicle according to a variant of the second embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view of a vehicle fuel storage system according to a third embodiment of the present invention. [Figure 5] FIG. 10 is a cross-sectional view of a fuel storage system for a vehicle according to a variant of the third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] FIG. 1 shows a vehicle fuel storage system 2 according to a first embodiment of the present invention.

[0029] The fuel storage system 2 includes a fuel tank 4, typically made of a plastic material, configured to store fuel used by the vehicle, particularly for its propulsion. The tank 4 defines an interior volume within which the fuel resides in the form of a liquid or gas, the proportions of which vary depending on conditions such as the pressure and temperature within the tank 4. The tank typically includes a fill line that allows the tank to be refueled, a vent line that allows fuel vapors to be released under certain conditions, and a fill line that allows fuel to be directed to the vehicle's engine. These three lines are well known in the art and will not be illustrated or further described herein.

[0030] The fuel storage system 2 includes an inflatable bladder 6 that extends inside the tank 4. The bladder 6 has elastically deformable walls that allow it to expand and contract without plastic deformation. To this end, the fuel storage system 2 includes an air supply line 8 that is connected to the bladder 6 and to an air supply system (not shown) located outside the tank 4. The air supply line 8 allows the bladder 6 to alternately fill with air, causing it to occupy a larger volume within the tank 4, and to release some of the air contained within the bladder 6, causing it to occupy a smaller volume within the tank 4.

[0031] The fuel storage system 2 comprises at least one thermal accumulator 10 extending inside the tank 4 and configured to exchange heat with the fuel. In Figure 1, the fuel storage system 2 comprises one thermal accumulator 10, but the system may be equipped with multiple thermal accumulators, for example two or more thermal accumulators.

[0032] The heat storage device 10 includes a phase change material 12 housed in a container that is impermeable to both the material itself and the fuel, preventing mass exchange between the fuel and the heat storage device 10. On the other hand, the heat storage device 10 container is thermally conductive, allowing heat exchange between the fuel and the phase change material 12. The phase change material 12 has a melting point between 18°C ​​and 40°C. In examples, the phase change material is calcium chloride hexahydrate (CaCl2.6H2O), octadecane (C 18 H 38 ), cyclohexanol (CH 12 Preferably, the phase change material has a melting point between 20°C and 30°C, i.e. close to the range of fuel temperatures.

[0033] According to this embodiment, the heat accumulator 10 is fixed inside the tank 4 to the bottom wall 14 of the tank.

[0034] When the fuel temperature rises, for example, because the outside air temperature exceeds the fuel temperature, some of the fuel evaporates, generating fuel vapor within the tank 4. The tank 4 defines a closed volume, and the generation of fuel vapor causes a pressure increase in the gas phase within the tank. The following describes how the fuel storage system 2 according to the present invention can suppress this pressure increase.

[0035] Meanwhile, bladder 6 is compressed by the action of the pressure in the gas phase inside tank 4. Because the walls of bladder 6 are deformable, a stress equilibrium is established on the walls, which causes some of the air contained in bladder 6 to be expelled through air inlet 8. This reduces the volume of bladder 6 extending into tank 4, increasing the volume occupied by the fuel vapor and reducing the pressure of the fuel vapor. If the fuel temperature drops, for example because the outside air temperature drops below the temperature of the fuel, some of the fuel vapor condenses. This reduces the amount of fuel vapor in the tank and reduces the pressure of the fuel vapor. A new stress equilibrium is established on the walls of the bladder, which causes air inlet 8 to replenish bladder 6 and increases the volume of bladder 6 extending into tank 4.

[0036] On the other hand, the heat storage device 10 has a heat capacity that can absorb part of the heat of the fuel. When the temperature of the heat storage device 10 reaches the melting point of the phase change material 12, the material 12 begins to melt. Because the melting reaction is an endothermic reaction, the phase change material 12 supplies heat to the reaction by absorbing the heat of the fuel, thereby suppressing the temperature rise of the fuel. In other words, suppressing the temperature rise of the fuel suppresses the pressure rise of the fuel vapor in the tank.

[0037] A vehicle fuel storage system 2 according to a second embodiment of the present invention is shown in Figure 2. In this figure, elements similar to those in the previous figures are given the same reference numerals.

[0038] The vehicle fuel storage system 2 of FIG. 2 differs from that of FIG. 1 in that it includes multiple thermal accumulators 10, all of which are fixed to the wall of the bladder 6. This configuration contributes to facilitating the deployment of the bladder when it is filled with air, and also contributes to breaking up waves of fuel that occur when the fuel moves within the tank while the vehicle is moving, with the thermal accumulators 10 providing the bladder 6 with a so-called "anti-slosh" or wave-busting role.

[0039] Figure 3 shows a vehicle fuel storage system 2 according to a variant of the second embodiment of the invention, in which elements similar to those in the previous figures have been given the same reference numerals.

[0040] The vehicle fuel storage system 2 of Figure 3 differs from that of Figure 2 in that it further comprises at least one heat accumulator 10 fixed to the bottom wall 14 of the tank in addition to the one fixed to the wall of the bladder 6, thereby achieving the technical advantages provided by the two positions of the heat accumulators described above.

[0041] A vehicle fuel storage system 2 according to a third embodiment of the present invention is shown in Figure 4. In this figure, elements similar to those in the previous figures are given the same reference numerals.

[0042] The vehicle fuel storage system 2 in Fig. 4 differs from those in the previous figures in that it includes a plurality of thermal accumulators 10 manufactured in the form of floating bodies configured to float on the fuel in the tank 4. The thermal accumulators 10 are designed to be in constant contact with the fuel, and therefore can effectively exchange heat with the fuel. For ease of viewing, the bladders and air supply pipes are not shown in Fig. 4, but as explained above, the vehicle fuel storage system 2 includes the bladders and air supply pipes.

[0043] Figure 5 shows a vehicle fuel storage system 2 according to a variant of the third embodiment of the invention, in which elements similar to those in the previous figures have been given the same reference numerals.

[0044] The vehicle fuel storage system 2 of Figure 5 differs from that of Figure 4 in that the thermal accumulator 10 is fixed to a support plate 16 configured to float on the fuel in the tank 4. The support plate 16 not only ensures good thermal contact between the thermal accumulator 10 and the fuel, but also allows the thermal accumulator 10 to be properly distributed within the volume of the tank 4 rather than concentrated in one location within the tank 4. This prevents the fuel away from the thermal accumulator 10 from becoming hotter than the remaining fuel, which could result in the generation of fuel vapor. For clarity, the bladder and air charge pipe are not shown in Figure 5, but the vehicle fuel storage system 2 is equipped with a bladder and air charge pipe as described above.

[0045] The invention is not limited to the embodiments described, and other embodiments will appear obvious to those skilled in the art, and in particular it is possible to combine each of the embodiments and variants shown above, in particular to combine different arrangements and configurations of the heat accumulators. [Explanation of symbols]

[0046] 2. Fuel storage system 4 Tank 6 Bladder 8 Air supply pipe 10 Heat storage 12 Phase change materials 14 Bottom wall 16 Support Plate

Claims

1. - a fuel tank (4); - at least one inflatable bladder (6) extending inside said tank (4); A vehicle fuel storage system (2) comprising: and at least one heat accumulator (10) extending inside the tank (4), the heat accumulator (10) comprising a phase change material (12) having a melting point between 18°C ​​and 40°C; A fuel storage system (2) for a vehicle, characterized in that the at least one heat accumulator (10) is fixed to the at least one bladder (6).

2. A fuel storage system (2) as described in claim 1, further comprising at least one heat accumulator (10) fixed to the bottom wall (14) of the tank (4).

3. A fuel storage system (2) as described in claim 1, further comprising at least one heat accumulator (10) made in the form of a float configured to float on the fuel in the tank (4).

4. A fuel storage system (2) according to any one of claims 1 to 3, comprising a plurality of heat accumulators (10).

5. 4. The fuel storage system (2) according to claim 3, wherein the heat accumulator (10) is fixed to a support plate (16) configured to float on the fuel in the tank (4).

6. 4. The fuel storage system (2) according to any one of claims 1 to 3, wherein the phase change material (12) has a melting point of between 20°C and 30°C.

7. The phase change material (12) is calcium chloride hexahydrate (CaCl 2 .6H 2 O), octadecane (C 18 H 38 ), cyclohexanol (C 6 H 12 0) glycerin derivatives, selected from the list of glycerin derivatives.

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