FR3068106A1 - LIQUEFIED NATURAL GAS RESERVOIR FOR AUTOMOTIVE VEHICLES - Google Patents

Abstract

The invention relates to a tank (5) for a motor vehicle for containing liquefied natural gas. According to the invention, the reservoir comprises: - a container (500) for storing liquefied natural gas, the container comprising an internal reinforcing structure, and - an outer envelope (50) disposed around said container, said container and said outer envelope each having a generally parallelepipedic general shape.

Description

Liquefied natural gas tank for motor vehicles

1. Technical field of the invention

The technical field of the present invention is that of liquefied natural gas tanks (G.N.L) intended to equip motor vehicles.

2. State of the art

The market for motor vehicles, and in particular for heavy goods vehicles, operating on liquefied natural gas has entered a phase of significant growth.

Liquefied natural gas is natural gas processed in liquid form. This liquid state is reached when the gas is cooled to a temperature of about -161 ° C at atmospheric pressure.

Liquefaction makes it possible to reduce the gas volume of natural gas and to store it in one or more tanks installed, for example, on the chassis of the truck.

In known manner, the liquefied natural gas contained in the tank is regasified so as to supply the engine of the truck.

This fuel is less polluting than petrol and diesel, and the autonomy of heavy goods vehicles using this fuel makes them suitable for long-distance road transport.

Heavy duty liquefied natural gas tanks are designed to meet strict safety requirements, particularly pressure and keeping the temperature very low, to keep the gas in its liquid phase.

The tanks usually used have a cylindrical shape and have a double stainless steel wall between which are arranged a multi-layer insulator and vacuum classically. Their weight is therefore relatively large and their useful volume is reduced.

The cylindrical shape of such tanks allows a uniform distribution of the stresses, related to the pressure of the gas, on the internal wall of the tank.

However, the tanks having this shape occupy a large space and are not suitable for spaces / compartments of various shapes of the vehicle in which they are intended to be installed.

3. Statement of the invention

To this end, the invention provides a tank for a motor vehicle intended to contain liquefied natural gas.

According to the invention, the tank comprises: a container for storing liquefied natural gas, the container comprising an internal reinforcing structure, and an external envelope disposed around said container, said container and said external envelope each having a generally substantially parallelepiped shape.

The invention provides a tank of liquefied natural gas with a double wall of generally substantially parallelepipedal shape comprising a container forming an internal wall and an external envelope disposed around said container forming an external wall. Between these walls, which are not in contact, an intermediate space is formed containing a vacuum and / or an insulating material.

The parallelepiped shape of the container optimizes its storage capacity in liquefied natural gas and the parallelepiped shape of the external envelope allows optimal integration of the tank into the architecture of the vehicle.

According to a particular aspect of the invention, the internal reinforcing structure comprises several reinforcing plates spaced along the longitudinal axis of said container and extending transversely to said longitudinal axis.

These reinforcing plates optimize the mechanical resistance of the container to the internal pressure of the liquefied natural gas and avoids the inertia phenomena of the fluid contained.

According to a particular aspect of the invention, said reinforcing plates are full and have at least one orifice for the passage of liquefied natural gas within said container.

According to a particular aspect of the invention, the container comprises a reinforcing rod extending parallel to said longitudinal axis and connecting the side walls of the container by crossing said reinforcing plates.

This reinforcing rod allows the funds, or side walls, of the container to be maintained.

According to a particular aspect of the invention, the internal reinforcement structure further comprises a reinforcement framework having a general shape substantially parallelepiped and disposed inside said container.

According to a particular aspect of the invention, said reinforcing plates have a solid central portion from which extend several branches crossing the wall of said reinforcing framework.

According to a particular aspect of the invention, the ends of the branches projecting from the external surface of said reinforcing frame have a slot for passage of a bar for securing the reinforcing plates to said reinforcing frame.

According to a particular aspect of the invention, the fastening bars extend in longitudinal grooves formed on the periphery of the outer surface of said reinforcing frame.

According to a particular aspect of the invention, said container is secured to said external envelope by suspension means.

According to a particular aspect of the invention, said container is connected at a first lateral end to said external envelope by suspension straps and at a second lateral end by a suspension ring.

According to a particular aspect of the invention, said suspension straps and said suspension ring are made of a thermally insulating material.

According to a particular aspect of the invention, said suspension ring is fixed to the internal surface of a side wall of said external envelope and is fitted onto a stud carried by the external surface of a side wall of the container.

According to a particular aspect of the invention, the external surface of at least one side wall of the container or of the external envelope comprises a connection plate carrying in particular at least one of the following elements:

- a connection element to another tank;

- a level gauge;

- a safety valve;

- a device for filling the container.

According to a particular aspect of the invention, the container and said external envelope are made of aluminum.

The internal reinforcement structure can also be made of aluminum, or of a composite material, for example.

According to a particular aspect of the invention, the wall of the container and the wall of the external envelope are spaced from each other, the intermediate space between these walls being filled with insulating means.

The invention also relates to a motor vehicle, such as a truck, comprising at least one tank as described above.

4. List of figures

Other characteristics and advantages of the invention will appear more clearly on reading the following description of embodiments, given by way of simple illustrative and nonlimiting examples, and of the appended drawings, among which:

- Figure 1 is a perspective view of a first embodiment of a container used in a tank according to the invention;

- Figure 2 is a perspective view of a second embodiment of a container used in a tank according to the invention;

- Figure 3 is a perspective view of a third embodiment of a container used in a tank according to the invention;

- Figure 4 is a perspective view of a fourth embodiment of a container used in a tank according to the invention;

- Figure 5A is a perspective view of a fifth embodiment of a container used in a tank according to the invention;

- Figure 5B is a detail view of the container of Figure 5A showing the passage of a reinforcing bar in the branches of the reinforcement plates of the container;

- Figures 6A and 6C are perspective views of a tank according to the invention having first and second means for securing the container to the outer envelope;

FIGS. 6B and 6D are detailed views of FIGS. 6a and 6c respectively showing the first and second securing means,

FIG. 7 is a perspective view of a possible installation of a tank according to the invention on a motor vehicle, and

- Figures 8a to 8m schematically illustrate examples of container section that can be implemented in a tank according to the invention.

In these figures, the reference number of the same elements is incremented by 100 between successive embodiments.

5. Detailed description of the invention

The invention relates to a tank for a motor vehicle intended to contain liquefied natural gas.

According to the invention, the tank comprises: a container for storing liquefied natural gas, the container comprising an internal reinforcing structure, and an external envelope disposed around said container, said container and said external envelope each having a generally substantially parallelepiped shape.

There is shown in Figure 1, in perspective, a container, according to a first embodiment, implemented in a motor vehicle tank according to the invention.

The interior space of the container 100 constitutes a sealed enclosure for the storage of liquefied natural gas under pressure (up to 20 bars, for example).

The container 100 is intended to be housed in an external envelope (not shown) of the tank.

The container 100 and the external envelope each have a generally substantially parallelepiped shape.

In this example, the container 100 is made of aluminum and has a length of two meters.

The container 100 extends longitudinally along the longitudinal axis Ax and its cross section to the axis Ax is a square whose angles are rounded.

The lateral faces 102, 103 situated at the longitudinal ends of the container 100 are slightly curved or curved towards the outside thereof in order to improve the distribution of the stresses linked to the pressure of the liquefied natural gas under pressure.

The container 100 further comprises several planar reinforcing plates 110 disposed inside the container 100 and spaced along the longitudinal axis Ax.

These plates extend transversely to the longitudinal axis Ax and their outer periphery comes into contact with the internal wall of the container 100.

The reinforcement plates 110 have a plurality of openings 111. Such openings allow the homogeneous distribution of the pressurized fluid throughout the container 100.

As shown, the container 100 comprises seven reinforcing plates 110 each comprising five openings 111, namely a central opening 112 and four peripheral openings 113.

The openings 111 of each reinforcement plate 110 are aligned with the openings 111 of the adjacent reinforcement plates 110.

The parallelepiped shape of the container 100 optimizes its fuel storage capacity and allows optimal integration into the architecture of the vehicle.

Figure 2 illustrates a container, according to a second embodiment, implemented in a motor vehicle tank according to the invention.

The container 200 extends longitudinally along the axis Ax and its cross section along the axis Ax is a square whose angles are rounded.

The container 200 is intended to be housed in an external envelope (not shown) of the tank.

The container 200 and the outer envelope each have a generally substantially parallelepiped shape.

The lateral faces 202, 203 situated at the longitudinal ends of the container 200 are slightly curved towards the outside of the latter.

The container 200 further comprises several planar reinforcing plates 210 disposed inside the container 200 and spaced along the longitudinal axis Ax.

These plates extend transversely to the longitudinal axis Ax and their outer periphery comes into contact with the internal wall of the container 200.

The reinforcement plates 210 have a single central opening 212.

The lateral faces 202, 203 of the container 200 each carry a plate 220, 230 respectively.

The plates 220, 230 are connected by a tube or a rod 240 passing longitudinally through the container 200 passing through the central opening of each internal reinforcement plate 210.

The tube or rod 240 projects from the outer surface of each of the plates 220, 230.

The tube or rod 240 allows the funds, or side walls, of the container 200 to be maintained, and thus serves as reinforcement.

At least one of the plates 220, 230 carries in particular at least one of the following elements:

- a connection element to another tank;

- a level gauge;

- a safety valve;

- a device for filling the container.

It will be noted that all or part of these elements can, in a variant, be carried by at least one of the side walls of the external envelope in which the container is intended to be housed.

Figure 3 illustrates a container, according to a third embodiment, implemented in a motor vehicle tank according to the invention.

The container 300 extends longitudinally along the axis Ax and its cross section along the axis Ax is a square whose angles are rounded.

The container 300 is intended to be housed in an external envelope (not shown) of the tank.

The container 300 and the outer envelope each have a generally substantially parallelepiped shape.

The lateral faces 302, 303 situated at the longitudinal ends of the container 300 are planar.

The container 300 further comprises several planar reinforcing plates 310 disposed inside the tank 300 and spaced along the longitudinal axis Ax. These plates extend transversely to the longitudinal axis Ax and their outer periphery comes into contact with the internal wall of the container 300.

The reinforcement plates 310 have a single central opening 312.

Furthermore, several parallel recesses 305 extend around the periphery of the outer surface of the container 300.

As illustrated, the recesses 305 have a semi-circular section and extend transversely to the longitudinal axis Ax over the entire periphery of the container 300.

Such recesses 305 make it possible to improve the mechanical resistance of the container 300 to the internal pressure of the liquefied natural gas.

It can also be envisaged, as an alternative, that the recesses have a different shape and / or that they extend partially around the periphery of the outer surface of the container.

Figure 4 illustrates a container, according to a fourth embodiment, implemented in a motor vehicle tank according to the invention.

The container 400 extends longitudinally along the axis Ax and its cross section along the axis Ax is a square whose angles are rounded.

The container 400 is intended to be housed in an external envelope (not shown) of the tank.

The container 400 and the outer envelope each have a generally substantially parallelepiped shape.

The container 400 comprises several flat reinforcement plates 410 arranged inside the container 400 and spaced along the longitudinal axis Ax. These reinforcement plates 410 extend transversely to the longitudinal axis Ax and their outer periphery comes into contact with the internal wall of the container 400.

Each reinforcement plate 410 comprises a single central opening 412 and several lateral slots 414.

Such slots 414 allow the passage of reinforcement crosspieces 450 disposed against the internal wall of the container 400 and extending along the longitudinal axis Ax over the entire length of the container 400.

A tube or rod 440 passing longitudinally through the container 400 passing through the central opening 412 of each internal reinforcement plate 410.

The tube or rod 440 projects from the outer surface of the side faces 402, 403, and serves as a reinforcement.

FIG. 5A illustrates a container, according to a fifth embodiment, used in a motor vehicle tank according to the invention, FIG. 5B being a detailed view of the container.

The container 500 (illustrated without its side walls) is intended to be housed in an external envelope (not shown) of the tank.

The container 500 and the external envelope each have a generally substantially parallelepiped shape, the section of the container 500 being slightly smaller than that of the external envelope so that it can be accommodated there.

The square section of the container 500 allows an increase in the useful volume of the latter.

In this example, the container 500 is made of aluminum, has a length of 2.30 m and a storage capacity of 584 liters of gas (or 188 kg of gas).

The tank has a weight of 329 kg.

Compared to a stainless steel tank of the same length and of cylindrical section, the parallelepipedal aluminum tank of the invention has a reduced weight of the order of 3% and a useful volume of the container increased by 4%, which allows fuel savings and reduced CO2 emissions.

The parallelepiped shape of the container 100 optimizes its fuel storage capacity and the parallelepiped shape of the external envelope allows optimal integration of the tank into the architecture of the vehicle.

For a similar vehicle architecture, a tank according to the invention has a fuel storage capacity greater by at least 12% compared to the cylindrical tanks of the prior art, up to 25% depending on the size of the wheel arch. of the heavyweight.

The container 500 here has a reinforcing structure comprising:

- A reinforcing frame 550, intended to be disposed against the internal wall of the container 500, of generally substantially parallelepiped shape and whose cross section, along the longitudinal axis Ax, is substantially square (the angles being rounded). The reinforcing frame 550 comprises several longitudinal grooves 551, having a U-shape, which extend over its outer surface and in which through lumens are formed at regular intervals along the longitudinal axis Ax.

- several 510 reinforcement plates. Each reinforcement plate 510 has a solid central portion 510 ′ from which extend in the plane of the central portion 510 ′ several branches 515 spaced apart from each other around this central portion 510 ′.

The ends 516 of the branches 515 pass through the openings made in the grooves 551 of the reinforcement frame 550 and project relative to the bottom of the grooves (without however exceeding the portions of the exterior surface of the frame connecting the grooves).

Each of these projecting ends 516 has a slot 517 for the passage of a connecting bar 560 of the reinforcement plates 510 to the reinforcement frame 550.

As illustrated in FIGS. 5A and 5B, the securing bars 560 pass through the aligned slots of each of the reinforcement plates 510.

These connecting bars 560 allow a distribution of the stresses along the container 500 and the maintenance of the internal reinforcement plates 510.

Thus, the reinforcement plates 510 are arranged inside the reinforcement framework 550 and are spaced along the longitudinal axis Ax.

These reinforcement plates 510 extend transversely to the longitudinal axis Ax and have a star structure.

As illustrated, the solid central portion section 510 ′ of the reinforcement plate 510 is square, the angles being rounded. From each of these rounded angles extend three straight branches 515 spaced from each other by an angle a of 45 ° in this example and the central branch of which is aligned, or substantially aligned, with the diagonal of the central portion full 510 '.

Furthermore, a reinforcement tube or rod 540 extends parallel to the longitudinal axis Ax and passes through the reinforcement plates 510 in the middle.

It is noted that the container 500, the reinforcing frame 550 and the reinforcing plates 510 are made of aluminum and that the reinforcing frame 550 and the reinforcing plates 510 are, for example, welded to each other.

The reinforcement frame 550 is a corrugated aluminum sheet welded around the reinforcement plates 510.

Alternatively, the reinforcing frame 550 is made of another material, such as a composite material.

At least one of the side walls of the container 500 carries in particular at least one of the following elements:

- a connection element to another tank;

- a level gauge;

- a safety valve;

- a device for filling the container.

It will be noted that all or part of these elements can, in a variant, be carried by at least one of the side walls of the external envelope in which the container is intended to be housed.

FIGS. 6A to 6D illustrate a reservoir 6 according to the invention comprising a container 600 and an external envelope 60, the walls of which are spaced apart.

These two elements, which are visible in transparency in FIG. 6a, each have a generally substantially parallelepiped shape, the section of the container being slightly smaller than that of the external envelope so that it can be accommodated there.

Between the spaced walls of the container 600 and the outer envelope 60 are arranged a multi-layer insulator and / or a vacuum (which thus make it possible to avoid heat exchanges by indirect contact between the container and the outer envelope).

The reservoir 6 implements means MSI, MS2 for securing the container 600 to the external envelope 60.

FIGS. 6A and 6B show the first securing means MSI and FIGS. 6C and 6D show the second securing means MS2.

As illustrated in FIGS. 6A and 6B, the first MSI connection means include:

a stud 606 of frustoconical shape carried by a first external lateral face 602 of the container 600, and

a suspension ring 64 carried by a first internal lateral face of the external envelope 60 and intended to be fitted onto the stud 606, the internal lateral face of the external envelope 60 being situated opposite the first external lateral face 602 from container 600.

Furthermore, the height of the stud 606 is less than the thickness of the suspension ring 64.

Thus, when the suspension ring 64 is fitted onto the pad 606, the planar surface of the pad 606 is not in contact with the first internal lateral face of the external envelope 60.

The suspension ring 64 is made of a thermally insulating material.

These aspects thus make it possible to avoid heat exchanges by direct contact between the container 600 and the external envelope 60. It is indeed crucial to prevent the temperature of the liquefied natural gas from increasing and that it remains in liquid form. .

As illustrated in FIGS. 6C and 6D, the second securing means MS2 comprise several straps 67 situated on the side of the second external lateral face 603 of the container 600 and of the second internal lateral face of the external envelope 60 which are arranged opposite.

In the example illustrated in FIG. 6C, four straps 67 are provided connecting each of the edges or edges of the container 600 to each of the edges or edges of the outer envelope 60.

Each of the straps 67 is made of a thermally insulating material.

Each strap 67 is pivotally connected:

at a first end to a support 631 secured to the external envelope 60, and

- At a second end of a Y-shaped element 632 which is movably mounted on a support 607 secured to the container 600 (Figure 6D).

A nut 634 which is mounted on a threaded rod 633 forming the base of the Y makes it possible to move in translation (in the directions of the double arrow in FIG. 6D) the element 632 in the form of Y and therefore to adjust the tension of the strap 67.

The tension of the straps 67 is chosen so as to minimize the sloshing of the container 600, even in the event of a vehicle collision.

FIG. 7 illustrates an example of installation of a tank according to the invention on a motor vehicle, in this case a heavy goods vehicle, of which only the support frames 9, 9 ′ are visible.

A section through the wall of the reservoir 7 makes it possible to distinguish the various constituent elements of such a reservoir.

The structure of the reservoir 7 as shown corresponds to that of the reservoir of the embodiment illustrated in FIGS. 5A and 5B.

Such a reservoir 7 therefore comprises an external envelope 70 surrounding a container 700, the latter comprising a reinforcing frame 750. The branches 715 of the reinforcing plates 710, extend transversely to the longitudinal axis of the reservoir 7, and are secured to the reinforcement frame 750 by reinforcement bars 760.

A side wall of the reservoir 7 is mechanically and fluidly coupled to a technical box 8.

The tank 7 and the technical box 8 are fixed to the support frames 9, 9 'of the vehicle by means of straps 10, 10'.

A distinction is made between the insulating means arranged in the space between the walls of the external envelope 70 and of the container 700.

Other aspects and variants

The tank according to the invention can be installed on other types of motor vehicles, such as buses.

Figures 8a to 8m illustrate the section of different containers of a tank according to the invention obtained by an extrusion process.

These integral container structures use internal reinforcements extending longitudinally.

In FIGS. 8a to 8i, each of the containers has an external section of square shape with rounded edges and an internal structure comprising:

- four teardrop-shaped channels which are arranged edge to edge in FIG. 8a,

- four tubular channels in FIG. 8b,

- four overlapping channels in the form of a drop of water in FIG. 8c,

a central channel bordered by peripheral channels in FIG. 8d,

a central tubular channel bordered by peripheral tubular channels in FIG. 8e,

- rows of tubular channels in FIGS. 8f and 8i,

- a combination of honeycomb shaped channels surrounding four square section channels in FIG. 8g,

- honeycomb channels surrounding a central channel in FIG. 8h,

- a central tubular channel surrounded by partially tubular channels in FIG. 81.

The containers of FIGS. 8j and 8k have a curved and polygonal external section respectively without internal reinforcement structure.

The container of FIG. 8m has an external section in four-leaf clover with an internal reinforcement channel.

The tank of the invention can be assembled with other tanks of the same type.

Thus, the tank obtained by such an assembly can be housed in vehicle compartments of complex shapes.

In other words, the shape of the tank can be adapted to the volumes available on the chassis of the vehicle.

Claims (16)

1. Tank (5) for a motor vehicle intended to contain liquefied natural gas, characterized in that it comprises: a container (500) for storing liquefied natural gas, the container comprising an internal reinforcement structure, and an external envelope (50) disposed around said container, said container and said external envelope each having a generally substantially parallelepiped shape. 2. Tank (5) according to claim 1, characterized in that the internal reinforcement structure comprises several reinforcement plates (510) spaced along the longitudinal axis Ax of said container and extending transversely to said longitudinal axis Ax. 3. Tank (5) according to claim 1 or 2, characterized in that said reinforcing plates (510) are full and have at least one orifice for the passage of liquefied natural gas within said container. 4. Tank (5) according to claim 2 or 3, characterized in that the container (500) comprises a reinforcing rod (540) extending parallel to said longitudinal axis Ax and connecting the side walls of the container by crossing said reinforcing plates . 5. Reservoir (5) according to claim 2 or 4 when it depends on claim 2, characterized in that the internal reinforcement structure further comprises a reinforcement framework (550) having a generally substantially parallelepipedal shape and disposed at the inside said container. 6. Tank (5) according to claim 5, characterized in that said reinforcing plates have a solid central portion (510 ') from which extend several branches (515) passing through the wall of said reinforcing frame. 7. Tank (5) according to claim 6, characterized in that the ends (516) of the branches protruding from the outer surface of said reinforcing frame have a slot (517) for passage of a securing bar (517) of the reinforcing plates to said reinforcing frame. 8. Tank (5) according to claim 7, characterized in that the securing bars extend in longitudinal grooves (551) formed around the periphery of the outer surface of said reinforcing frame. 9. Tank (5) according to any one of the preceding claims, characterized in that said container is secured to said outer envelope by suspension means (MSI, MS2). 10. Tank (5) according to claim 9, characterized in that said container is connected at a first lateral end to said external envelope by suspension straps (67) and at a second lateral end by a suspension ring (64) . 11. Tank (5) according to claim 10, characterized in that said suspension straps and said suspension ring are made of a thermally insulating material. 12. Tank (5) according to claim 11, characterized in that said suspension ring (64) is fixed to the inner surface of a side wall of said outer envelope and is fitted on a stud (606) carried by the surface exterior of a side wall (602) of the container. 13. Tank (5) according to any one of the preceding claims, characterized in that the external surface of at least one side wall of the container or of the external envelope comprises a connection plate (220, 230) bearing in particular at minus one of the following: - a connection element to another tank; - a level gauge; - a safety valve; - a device for filling the container. 14. Tank (5) according to any one of the preceding claims, characterized in that the container and said outer envelope are made of aluminum. 15. Tank (5) according to any one of the preceding claims, characterized in that the wall of the container and the wall of the external envelope are spaced from each other, the intermediate space between these walls being filled insulating means. 16. Motor vehicle, such as a truck, comprising at least one tank according to one of claims 1 to 15.