FR3139878A1 - Pressurized gas tank for vehicle - Google Patents

Abstract

The invention relates to a pressurized gas tank (3) for a vehicle, comprising: - a liner (7) based on plastic material, - a composite reinforcing structure (9) wound around the liner (7), characterized in that that the tank (3) comprises: - an electric heating device (11) configured to maintain the liner (7) at a temperature above a predetermined threshold, the electric heating device (11) comprising a self-regulated heating strip (21) in temperature, the heating strip (21) being arranged between the liner (7) and an external surface (23) of the composite reinforcement structure (9). The invention also relates to a vehicle comprising such a tank, a method of manufacturing such a tank, as well as a method of thermal regulation of such a tank. Figure for abstract: figure 2

Description

Pressurized gas tank for vehicle

The invention relates to the field of pressure tanks for vehicles, such as a motor vehicle, a truck, a bus, a train or even a boat. The invention relates more particularly to a pressurized gas tank for a vehicle, as well as a vehicle comprising such a pressurized gas tank.

We already know in the state of the art, a pressurized gas tank for example configured to store gas at a pressure of at least 350 bar or at least 700 bar, the gas being for example hydrogen. Thus, this pressurized gas tank is configured to be used by the vehicle equipped with the pressurized gas tank for various functions, as a source of energy.

Such a pressurized gas tank is conventionally composed of an internal envelope called a liner, which has a sealing function with respect to the gas contained in the tank. The liner is for example made of a plastic material, chosen for its lightness and low manufacturing cost, or of a metal such as aluminum, or of another material such as a metal alloy. The liner is generally generally cylindrical in shape and has two dome-shaped ends. The liner has an opening, which is generally surmounted by a tip. The pressurized fluid exerts strong stresses on the internal surface of the liner, which can damage the integrity of the liner and cause dangerous leaks, particularly with combustible gases such as hydrogen.

To improve the mechanical properties of the pressurized gas reservoir, the liner is surrounded by a composite reinforcing structure, generally produced by winding around the liner strips of composite material based on thermosetting polymer, for example based on epoxy resin, loaded of glass and/or carbon fibers, or by winding around the liner a filament made of a reinforcing fiber, for example carbon fiber, the filament being embedded in a resin, for example an epoxy resin, to facilitate rolling up and ensure that the outer surface of the liner is covered.

Furthermore, such a pressurized gas tank generally comprises a functional member attached to the end piece, which supports functional components such as a solenoid valve, in order for example to distribute the fluid from the tank to a combustion engine and/or to a energy conversion means on board the vehicle, such as a fuel cell, configured to supply energy to vehicle propulsion means, such as an electric motor.

When distributing gas out of the pressurized gas tank, the temperature of the gas stored in the pressurized gas tank decreases. It is necessary that this temperature does not fall below a predetermined threshold, for example equal to -40°C, in order to avoid deterioration of the constituent components of the pressurized gas tank, in particular of the liner, for example due to the materials constituting these components. It is thus known to heat a pressurized gas tank in order to avoid damaging the liner when the temperature of the gas contained therein is too low, for example by placing a heating element within the pressurized gas tank, in the internal space delimited by the liner. However, such a heating element occupies a significant space in the tank, which reduces its storage capacity. A known alternative is to arrange an external heating element such as a heating band around the pressurized gas tank. However, this heating element does not allow the liner to be heated quickly and efficiently, due to the fact that the heating element is separated from the liner by components of the pressurized gas tank which limit heat transfer, such as for example the reinforcing structure. composite. In addition, it is necessary to limit the heating power so that the heating element does not in any case damage, even locally, the components of the tank such as for example the liner due to a too high temperature, for example above 85 °C.

The invention aims in particular to provide a pressurized gas tank making it possible to heat the liner quickly and efficiently, while avoiding damaging the components of the pressurized gas tank.

To this end, the subject of the invention is a pressurized gas tank for a vehicle, comprising:
- a liner based on plastic material,
- a composite reinforcement structure wrapped around the liner,
characterized in that the tank comprises:
- an electric heating device configured to maintain the liner at a temperature above a predetermined threshold,
the electric heating device comprising a heating strip self-regulated in temperature, the heating strip being arranged between the liner and an external surface of the composite reinforcing structure.

Such a pressurized gas tank allows the liner to be heated quickly and efficiently, while avoiding damage to the tank components. Thus, thanks to the use of such a heating strip, heating is carried out quickly and efficiently. In addition, the use of such a self-regulated heating strip ensures that at any point, the temperature of the strip due to heating is not too high. This thus avoids damaging the tank components, and primarily the liner, due to excessive local heating.

Depending on other optional characteristics of the tank, taken alone or in combination:

- The liner is based on polyamide, preferably based on PA6 or PA66, preferably PA6. Indeed, polyamide like PA6 has an excellent gas barrier effect at high pressure.

- The heating strip is a PTC positive temperature coefficient thermistor. Thus, the heating strip is self-regulated in temperature in a simple and economical manner.

- The predetermined threshold is greater than -45°C, preferably equal to -40°C. In fact, a liner made of plastic material is more fragile below such a temperature.

- The heating strip is self-regulated in temperature such that its maximum temperature is less than 120°C, preferably less than 100°C, preferably less than 85°C, even more preferably less than 80°C. Indeed, the plastic material of the liner is likely to degrade above such a temperature.

- The tank is configured to store gas at a pressure of at least 350 bar, preferably at least 700 bar.

- The heating strip is placed between the liner and the composite reinforcement structure. Thus, the positioning of the heating strip between the liner and the composite reinforcement structure makes it possible to reduce the vibrations suffered by the heating strip and limits the risk of the heating strip detaching.

- The tank includes a temperature sensor placed between the liner and an external surface of the composite reinforcement structure, and preferably placed directly on the liner. Thus, the temperature of the liner can be measured, which makes it possible to start heating by the heating strip when the temperature is less than or equal to the predetermined threshold, preferably when the temperature measured by the temperature sensor is less than or equal to 35° vs.

- The heating strip extends at an angle of between 85° and 90° relative to a longitudinal axis of the tank. Thus, manufacturing is facilitated, due to the geometry similar to that of at least part of the composite reinforcement structure, namely the hoop-type layers.

- The heating strip is formed in a helix around the liner.

- The liner includes a groove configured to receive the heating strip. Thus, the manufacture of the reinforcing structure is facilitated, due to the fact that the groove makes it possible to obtain a more regular external surface of the assembly formed by the liner and the heating strip, the heating strip not being or only slightly projecting. outside the radially outermost surface of the liner.

- The heating strip is wound together with the composite reinforcement structure. Thus, manufacturing is optimized, because mounting the heating strip does not require a specific assembly step.

- The heating strip is wound directly on the liner. Thus, manufacturing is simplified, due to the fact that the liner is already designed to support the winding of the reinforcing structure.

- The liner includes a cylindrical central portion. Thus, manufacturing by winding the reinforcing structure around the liner is facilitated. For example, the section of the central cylindrical portion is a circle or an ellipse.

- The heating strip is arranged radially between the liner and an external surface of the composite reinforcement structure.

- The heating strip has a width greater than its thickness, preferably at least 5 times greater, preferably at least 10 times greater.

- The heating strip has a thickness less than 5 mm, preferably less than 3 mm, preferably less than 1 mm, more preferably equal to 0.5 mm. A low thickness makes it easier to wind the heating strip.

- The heating strip includes a sheath made of the same material as the liner. Thus, the cohesion between the liner, the heating strip and the composite reinforcement structure is improved.

- The tank comprises a tip placed on an end opening of the liner, the tip being metallic, preferably aluminum.

- The internal surface of the heating strip is at least 30%, preferably at least 60%, of the external surface of the liner. Thus, the heating surface is relatively large and makes it possible to improve the speed of heating.

- The composite reinforcement structure comprises hoop-type layers – “hoop layers” in English – extending at an angle of between 85° and 90° relative to a longitudinal axis of the tank and helical-type layers – “helical layers” in English – extending at an angle between 5° and 85° relative to a longitudinal axis of the tank.

- The heating strip extends at an angle of between 5° and 90°, preferably between 85° and 90°, relative to a longitudinal axis of the tank. Thus, the heating strip can be assembled on the tank with means similar to the means of manufacturing the composite reinforcement structure. As a result, manufacturing is optimized.

- The reservoir includes smoothing means, the external surface of which is flush with the external surface of the heating strip. Thus, the structural strength of the tank is improved, as the composite reinforcement structure is wrapped around a smoother surface. Indeed, to achieve good winding of the composite reinforcement structure, the surface on which the winding is applied must be smooth, otherwise irregularities in the area of connection with the liner and/or with the heating strip may occur. .

- The tank includes thermal transfer means configured to transfer heat from the heating strip to the liner.

- The heat transfer means are arranged between the liner and an external surface of the composite reinforcing structure.

- The smoothing means comprise or consist of the thermal transfer means. Thus, the manufacture of the tank is optimized, due to the fact that the heat transfer means are integrated into the smoothing means or form the smoothing means.

- The thermal transfer means are chosen from the group comprising a strip of thermal paste, a metal strip, a metal film, a metal wire, and their combinations.

- The heating strip is prefabricated in one piece with the smoothing means, so as to form a heating element. This makes manufacturing the tank easier.

- The heating member comprises heat transfer means, which are axially offset relative to the heating strip along a longitudinal axis of the tank. This provides heating over a large surface area of the liner while limiting the width of the heating strip.

- The heating strip has a nominal heating power of at least 750W, preferably at least 1500W.

- The heating band extends axially along a longitudinal axis of the tank.

- The heat transfer means extend at an angle of between 5° and 90°, preferably between 85° and 90°, relative to a longitudinal axis of the tank. Thus, the thermal transfer means can be placed on the tank with means similar to the means for manufacturing the composite reinforcement structure.

- The heating strip is printed on the liner. Thus, the manufacture of the heating strip is particularly simple, and ensures that the heating is effective, the heating strip directly heating the liner, due to its printing on the liner.

The invention also relates to a vehicle comprising a tank as described above.

The invention also relates to a method of manufacturing a tank as described above, comprising the following successive steps:
- step a): manufacture a liner based on plastic material by molding, for example by rotational molding or by blow molding or by extrusion blow molding,
- step b): wind a heating strip on the liner, for example in a groove in the liner,

- step c): wind a composite reinforcement structure on the liner and the heating strip.

According to an optional characteristic of the manufacturing process, step c) is carried out simultaneously with step b) when the heating strip is wound together with the composite reinforcing structure.

Finally, the subject of the invention is a process for thermal regulation of a reservoir as described above, comprising the following steps:
- measurement of the temperature of the liner, preferably by means of a temperature sensor placed between the liner and an external surface of the composite reinforcing structure, more preferably placed directly on the liner,
- supply of electrical energy to the heating strip when the measured temperature is less than or equal to the sum of the predetermined threshold and a tolerance value, the tolerance value preferably being between 0°C and 5°C, more preferably equal to 5°C.

Brief description of the figures

The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the appended drawings in which:

is a schematic view of a vehicle comprising a pressurized gas tank;

is a schematic view of a pressurized gas tank according to a first embodiment;

is a schematic sectional view of a detail of a pressurized gas tank according to a second embodiment;

is a schematic sectional view of a detail of a pressurized gas tank according to a third embodiment.

detailed description

In all figures, the same references relate to the same elements.

In this detailed description, the following achievements are examples. Although the description refers to one or more embodiments, this does not mean that the features apply only to a single embodiment. Simple features of different embodiments may also be combined and/or interchanged to provide other embodiments.

There schematically represents a vehicle 1, for example a motor vehicle, comprising a tank 3 of pressurized gas, in this example hydrogen. In this example, the vehicle 1 comprises a fuel cell 5 supplied with hydrogen by the tank 3. The tank 3 is configured to store gas at a pressure of at least 350 bar, preferably at least 700 bar. Thus, the tank 3 has an admissible storage pressure greater than 350 bar, preferably greater than 700 bar.

Tank 3, as shown on the , comprises a liner 7, a composite reinforcement structure 9 and an electric heating device 11.

Liner 7 is based on plastic material. In this example, the liner 7 is based on polyamide, preferably based on PA6 or PA66, preferably PA6. The liner 7 comprises a cylindrical central portion 13. In this example, the liner 7 also includes end portions 15 in the form of a dome. Thus, the liner 7 comprises an end opening on each of the end portions 15, on which a tip 19 is placed, the tip 19 being in this example made of aluminum. At least one end piece 19 is connected to functional elements making it possible to distribute the gas out of the tank 3 through the end piece 19, such as for example a solenoid valve.

The composite reinforcement structure 9 is wound around the liner 7. The composite reinforcement structure 9 comprises hoop-type layers – “hoop layers” in English – extending at an angle of between 85° and 90° relative to a longitudinal axis

The electric heating device 11 is configured to maintain the liner 7 at a temperature above a predetermined threshold. The predetermined threshold is greater than -45°C, preferably equal to -40°C. For this, the electric heating device 11 comprises a heating strip 21 self-regulated in temperature, the heating strip 21 being arranged between the liner 7 and an external surface 23 of the composite reinforcement structure 9.

The heating strip 21 is self-regulated in temperature such that its maximum temperature is less than 120°C, preferably less than 100°C, preferably less than 85°C, even more preferably less than 80°C. For example, the heating strip 21 is a PTC positive temperature coefficient thermistor. Such a heating strip 21 is composed for example of a layer of polymer loaded with carbon, which is placed between two sheets of copper or aluminum. Furthermore, the heating strip 21 comprises a sheath formed of the same material as the liner 7. The heating strip 21 has a nominal heating power of at least 750W, preferably at least 1500W. The heating strip 21 is arranged radially between the liner 7 and the external surface 23 of the composite reinforcement structure 9. In this example, the heating strip 21 is arranged between the liner 7 and the composite reinforcement structure 9. The heating strip 21 has a width greater than its thickness, preferably at least 5 times greater, preferably at least 10 times greater. The heating strip 21 has a thickness less than 5 mm, preferably less than 3 mm, preferably less than 1 mm, more preferably equal to 0.5 mm. The internal surface of the heating strip is at least 30%, preferably at least 60%, of the external surface of the liner 7. In this example, the heating strip 21 extends with an angle of between 5° and 90°, preferably between 85° and 90°, relative to the longitudinal axis not shown, the heating strip 21 extends axially along the longitudinal axis X of the tank 3.

Furthermore, the heating strip 21 is wound together with the composite reinforcement structure 9. Furthermore, in this example, the heating strip 21 is wound directly on the liner 7. Alternatively, the heating strip 21 is printed on the liner 7.

The tank 3 also includes a temperature sensor 25 placed between the liner 7 and the external surface 23 of the composite reinforcement structure 9. In this example, the temperature sensor 25 is placed directly on the liner 7.

According to a second embodiment of the tank 3', shown on the , this reservoir 3' is distinguished from the reservoir 3 according to the first embodiment described above in that the reservoir 3' comprises smoothing means 27', the external surface 29' of which is flush with the external surface 31' of the heating strip 21 '. In this example, the tank 3' also includes thermal transfer means 33' configured to transfer heat from the heating strip 21' to the liner 7'. The heat transfer means 33' are arranged between the liner 7' and an external surface 23' of the composite reinforcement structure 9'. The thermal transfer means 33' are chosen from the group comprising a strip of thermal paste, a metal strip, a metal film, a metal wire, and combinations thereof. The heat transfer means 33' extend at an angle of between 5° and 90°, preferably between 85° and 90°, relative to the longitudinal axis X of the tank 3'. In this example, the smoothing means 27' comprise or are constituted by heat transfer means 33'. Furthermore, the heat transfer means 33' are axially offset relative to the heating strip 21' along the longitudinal axis X of the tank 3'. According to an alternative embodiment, the heating strip 21' is prefabricated in one piece with the smoothing means 27', so as to form a heating member. The heating member thus comprises the heat transfer means 33', which are axially offset relative to the heating strip 21' along a longitudinal axis X of the reservoir 3'.

According to a third embodiment of the 3'' tank, shown on the , this reservoir 3'' is distinguished from the reservoir 3 according to the first embodiment described above and from the reservoir 3' according to the second embodiment described previously in that the liner 7'' comprises a groove 35'' configured to receive the 21'' heating strip. Thus, the heating strip 21'' is wound around the liner 7'' in the groove 35''. According to a variant not shown, the groove 35'' is also configured to receive the smoothing means and/or the thermal transfer means described above.

An example of a manufacturing process for a 3, 3', 3'' tank as defined previously is described below. Such a manufacturing process comprises the following successive stages:

- step a): manufacture a 7, 7', 7'' liner based on plastic material by molding, for example by rotational molding or by blowing or extrusion-blowing,

- step b): wind a heating strip 21, 21’, 21’’ on the liner 7, 7’, 7’’, for example in a groove 35’’ of the 7’’ liner,

- step c): wind a composite reinforcement structure 9, 9’, 9’’ on the liner 7, 7’, 7’’ and the heating strip 21, 21’, 21’’.

For example, step c) is carried out simultaneously with step b) when the heating strip 21, 21', 21'' is wound together with the composite reinforcement structure 9, 9', 9''.

An example of a thermal regulation process for a 3, 3', 3'' tank of the aforementioned type is described below. Such a thermal regulation process comprises the following steps:

- measurement of the temperature of the liner 7, 7’, 7’’, preferably by means of the temperature sensor 25,

- supply of electrical energy to the heating strip 21, 21', 21'' when the measured temperature is less than or equal to the sum of the predetermined threshold and a tolerance value, the tolerance value preferably being between 0° C and 5°C, more preferably equal to 5°C.

The invention is not limited to the embodiments presented and other embodiments will be clear to those skilled in the art. It is notably possible to combine the embodiments with each other.

Reference list

1: vehicle
3, 3', 3'': tank
5: fuel cell
7, 7', 7'': liner
9, 9', 9'': composite reinforcement structure
11: electric heating device
13: central portion
15: end portion
19: tip
21, 21', 21'': heating strip
23, 23', 23'': external surface of the composite reinforcement structure
25: temperature sensor
27': smoothing means
29': external surface of the smoothing means
31': external surface of the heating strip
33': means of thermal transfer
35'': groove

X: longitudinal axis of the tank

Claims (10)

Tank (3, 3', 3'') of pressurized gas for vehicle (1), comprising:
- a liner (7, 7', 7'') made from plastic material,
- a composite reinforcement structure (9, 9', 9'') wrapped around the liner (7, 7', 7''),
characterized in that the reservoir (3, 3', 3'') comprises:
- an electric heating device (11) configured to maintain the liner (7, 7', 7'') at a temperature above a predetermined threshold,
the electric heating device (11) comprising a heating strip (21, 21', 21'') self-regulated in temperature, the heating strip (21, 21', 21'') being arranged between the liner (7, 7', 7'') and an external surface of the composite reinforcement structure (9, 9', 9''). Tank (3, 3', 3'') according to the preceding claim, in which the heating strip (21, 21', 21'') is a thermistor with a positive temperature coefficient PTC. Tank (3, 3', 3'') according to any one of the preceding claims, in which the heating strip (21, 21', 21'') is arranged between the liner (7, 7', 7'') and the composite reinforcement structure (9, 9', 9''). Tank (3, 3', 3'') according to any one of the preceding claims, which comprises a temperature sensor (25) disposed between the liner (7, 7', 7'') and an external surface (23, 23', 23'') of the composite reinforcement structure (9, 9', 9''), and preferably placed directly on the liner (7, 7', 7''). Tank (3, 3', 3'') according to any one of the preceding claims, in which the heating strip (21, 21', 21'') extends at an angle of between 85° and 90° relative to to a longitudinal axis X of the tank (3, 3', 3''). Tank (3, 3', 3'') according to any one of the preceding claims, in which the heating strip (21, 21', 21'') is formed helically around the liner (7, 7', 7' '). Tank (3, 3', 3'') according to any one of the preceding claims, wherein the heating strip (21, 21', 21'') is wound together with the composite reinforcing structure (9, 9', 9''). Tank (3, 3', 3'') according to any one of the preceding claims, in which the heating strip (21, 21', 21'') is wound directly on the liner (7, 7', 7'' ). Tank (3'') according to any one of the preceding claims, wherein the liner (7'') comprises a groove (35'') configured to receive the heating strip (21''). Vehicle (1) comprising a tank (3, 3', 3'') according to any one of the preceding claims.