Method for managing pressure within a gas tank

Abstract

A computer implemented method which estimates pressure within a gas tank (fig 1), the gas tank may be a hydrogen gas tank in a vehicle which undergoes re-fuelling. The gas tank has a liner defining a

Description

Technical field The present invention generally relates to a method for managing pressure within hydrogen tanks. Background Art Pressure vessels are used in a wide variety of technical fields to store fluids under pressures significantly higher than atmospheric, typically between 350 and 700 bar. Many applications, such as hydrogen tanks for the automotive industry, require pressure vessels to be as light as possible whilst being strong enough to ensure reliable and durable sealing of the fluid within. Modern hydrogen tanks are typically cylindrical and can generally be categorized in five types: Type I tanks are simple metallic tanks, generally formed by a relatively thick cylinder of aluminum or steel. Type II tanks are similar to type I tanks and additionally comprise windings of glass or carbon fibers around the metallic cylinder. Type III tanks are made from a composite shell closely surrounding a relatively thin metallic liner. The metallic liner mainly ensures sealing of the fluid within the tank, whilst the composite shell bears most of the mechanical load generated by the pressure within. Type IV tanks are similar to Type III tanks but have a polymer liner instead of a metallic one. Finally Type V tanks are liner-less, fully composite tanks. Type III tanks are known to be prone to leakage and are thus considered to be unsuitable for some applications in the automotive industry. Indeed, hydrogen tanks are subject to cyclic variation of pressures as they are emptied during use and repressurized during refueling. These pressure cycles are susceptible to generate fatigue behavior on metallic liners, which eventually leads to the formation and subsequent propagation of cracks within the liner, enabling pressurized fluid to leak through. In hydrogen-fueled vehicles, these leaks can have catastrophic consequences due to the flammability of the fluid and must be prevented. Likewise, the composite shell of type IV tanks may be susceptible to fatigue due, e.g. to manufacturing defaults. Technical problem It is an object of the present invention to provide a method for managing pressure within hydrogen tanks, which improves the safety of the driver without increasing the weight of the tank. This object is achieved by a method as claimed in claim 1. General Description of the Invention To achieve this object, the present invention provides a computer-implemented method for managing pressure within a gas tank, wherein the gas tank comprises a liner defining a plenum chamber for the gas, a composite shell surrounding the liner, and an arrangement of strain sensing device embedded within the composite shell, the method comprising the steps of: - monitoring strain within the gas tank using data from the strain sensing device, - comparing the strain to a first predetermined threshold, - if the strain is greater than the first predetermined threshold, operating subsequent refueling of the tank such that the pressure within the tank does not exceed a predetermined maximum allowed pressure, which is lower than a nominal working pressure for the gas tank. By decreasing the maximum pressure at which the tank may be refueled, the amplitude of the pressure variations within the tank are reduced, thereby limiting possible fatigue behavior. The durability of the gas tank is thus improved and potential leaks are prevented long enough for the user to get the gas tank inspected. In embodiments, the strain is compared to a second predetermined threshold, the second predetermined threshold being higher than the first predetermined threshold, and if the computed strain is higher than the second predetermined threshold, a countdown is initiated, at the end of which the engine is automatically shut down. Preferably, if the computed strain is higher than the second predetermined threshold, a command preventing the engine from being restarted is enabled. If the strain is higher than the second predetermined threshold, a counter may be incremented each time the engine is restarted, and the command preventing the engine from being restarted may be enabled if said counter reaches a predetermined value. These measures prevent critical failure of the gas tank and incentivize the driver to route towards a nearby mechanic to get the gas tank inspected. In embodiments, the strain and / or the result of the comparison with a predetermined threshold are stored and associated to a corresponding date and time. In embodiments, the method further comprises the step of notifying the user of the strain within the hydrogen tank based on the result of the comparison with a predetermined threshold. In embodiments, the arrangement of strain sensing devices comprises at least one optical fiber, preferably two optical fibers, a light source configured to introduce light in said optical fiber, and a light receptor configured to receive light from said optical fiber and output a corresponding numerical signal, and the step of monitoring the strain is performed using the output signal from the light receptor. Preferably, said optical fiber comprises one or more Bragg gratings. The output signal of the light receptor may be transmitted to a processing unit, which may be configured to estimate a pressure within the gas tank from said output signal, preferably by implementing a trained neural network. In embodiments, when in faulty mode, the maximum allowed pressure is communicated to a refueling station during a refueling operation, or an abort instruction is sent to the refueling station when the in-tank pressure reaches the maximum allowed pressure. The inventive method finds particular application with: - Type III tanks where the liner is metallic. In such case it is desirable to put the strain sensing device directly against the liner, or within the composite but close to the liner. - Type IV tanks where the liner is made of plastic. In such case the strain sensing device is arranged within the composite, e.g. at a predetermined depth within the composite. Any appropriate type of strain sensing device may be employed. Their positioning in the tank, respectively in the composite, can be appropriately selected by the skilled person, to detect a certain degree of wear / damage due to fatigue behavior, e.g. based on experimentation. The invention further provides a processing unit comprising instructions which, when executed, implement the method as previously described. Preferably, said processing unit is an Engine Control Unit of a vehicle. The invention further provides a fuel delivery system comprising a gas tank with a liner and a composite shell, an arrangement of strain sensing device, numerical communication means, and the processing unit as described above, the arrangement of strain sensing device being configured to measure strain on the gas tank and being connected to the processing unit. The invention further provides a method for refueling a gas tank of a vehicle at a refueling station, said method comprising the steps of: i. communicating to the refueling station at least one of a tank pressure and tank temperature; ii. delivering a gas from the refueling station to the gas tank, iii. ending the delivery of gas if the tank pressure reaches the maximum allowed pressure defined by the method as previously described. It may be noted that gas tanks, respectively gas tanks assemblies, are conventionally equipped with a pressure sensor and a temperature sensor. Hence the inventive method may rely on existing sensors. Step i) is to be understood as the vehicle I control unit within the engine communicating with the fueling station. Normally, step i) involves at least communicating the initial tank pressure and temperature, i.e. before starting the gas delivery at the refueling station. These parameters are conventionally used to configure the gas delivery within the refueling station. In embodiments, the tank pressure is measured during delivering, and delivering is ended upon request by the gas tank, respectively vehicle, when the tank pressure reaches the maximum allowed pressure. Here, the pressure is monitored by the pressure sensor on the gas tank and a control unit associated with the gas tank / vehicle sends instructions to the refueling station to stop / abort the refueling when the in-tank pressure reaches the maximum allowed pressure. Alternatively or additionally, the method comprises communicating the maximum allowed pressure from the gas tank, respectively vehicle, to the refueling station. This is typically done before beginning the gas delivery. The refueling station may then be set to operate the gas delivery at a maximum delivery pressure corresponding to the maximum allowed pressure. Here, the refueling station is thus configured based on the maximum allowed pressure, in such manner to control the gas delivery at a maximum pressure (or target pressure) that corresponds to Paiiowed. In embodiments, these two approaches may be combined for improved safety. That is, the refueling station can be set to operated based on Paiiowed, and the vehicle ECU is itself able to send an abort message / instruction to the refueling station to interrupt the refueling when the in-tank pressure reached Paiiowed. Communicating may be achieved by any appropriate means. Communicating may be performed via short-range communication means from the gas tank, respectively vehicle, to the refueling station. However, the vehicle could also communicate with the refueling station over the Internet. Brief Description of the Drawings A preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Fig. 1 is a schematic diagram representing a cross section of a typical type III gas tank; Fig. 2 is a schematic diagram representing a side view of the type III gas tank of Fig.1; Fig. 3 is a flowchart of an embodiment of the method for managing pressure within a gas tank according to the invention; Fig. 4 is a flowchart of an embodiment of the method for refueling a vehicle powered by gaseous fuel according to the invention; Description of Preferred Embodiments The schematic diagram of figure 1 illustrates a type III hydrogen tank 1 having a spherocylindrical shape and comprising a spherocylindrical metallic liner 3 surrounded by a spherocylindrical composite shell 5. The liner 3 and the composite shell 5 are hollow, thereby defining a plenum chamber 7 in their inner volume. The liner 3 is relatively thin with a thickness t1 and can be made from any appropriate metal, e.g. aluminum, aluminum alloys, steel, stainless steel, titanium and / or titanium alloys, nickel-based alloys, etc. The liner 3 is typically formed as a spherocylinder, i.e. a cylinder with domes at both ends thereof. The liner acts as sealed reservoir for the pressurized hydrogen received therein. At least one of the domes is provided with an opening in which a boss 16 is fixed, as shown on figure 2. Such a spherocylinder can be manufactured by deep extrusion: an extruded pipe section is extruded and domes are sealingly attached at both ends. Alternately the liner 3 may be manufactured in one piece (cylinder + end domes) by additive manufacturing. These are only examples of liner construction and shall not be construed as limiting. The function of the liner 3 is mainly to fluidly seal the volume of the plenum chamber 7 from the atmosphere. The liner 3, due to its low thickness t1, is by itself not meant to bear the load generated by the high pressures within the plenum chamber 7. Instead, the liner 3 is closely surrounded by the composite shell 5 of comparatively larger thickness t2, which bears the vast majority of the mechanical load generated by the pressure inside the plenum chamber 7. The composite shell is best seen on the schematic diagram of figure 2, which illustrates a side view of the tank of figure 1. The composite shell 5 is typically formed by winding continuous resin coated filaments around the liner 3. The filaments may e.g. be glass or carbon fibers. The mechanical strength of the composite shell 5 largely depends on the configuration of its windings. Windings may be sorted in three patterns based on their winding direction. Polar windings 18 have a winding angle ap comprised between 0 and 30° and improve the mechanical strength of the composite shell in the longitudinal direction. Circumferential windings 20 (a.k.a. hoop windings) have a winding angle ac between 80 and 90° and improve the mechanical strength of the composite shell in the radial direction. Finally, helical windings 22 have a winding angle oh between 30 and 80°, slightly improve the mechanical strength of the composite shell in all directions, and mainly serve to maintain the polar windings in place, thereby preventing the latter from slipping. For the sake of clarity, only a single winding of each type is shown on figure 2, but composite shells normally comprise a multitude of such windings. In embodiments of the invention, a plurality of tanks as described above may be arranged and connected serially or in parallel, thereby forming a gas tank arrangement. Gas tanks are generally designed to achieve gas-tight sealing for a predetermined nominal working pressure (typically 350 or 700 bars) defined from the temperature of the tank in nominal condition. By design, the tank is built to resist a so-called burst pressure, Pburst, that may e.g represent 1.5 to 2 times the nominal working pressure. The nominal working pressure, noted Pnom is typically the target pressure value during tank filling, i.e. for a (re)fueling operation. In theory, as long as the burst pressure of the composite shell 5 is greater than the nominal working pressure of the tank 1, the tank 1 should be able to ensure fluid sealing. However, in practice, it has been observed that typical type III tanks start leaking after repeated usage, as fatigue of the metallic liner 3 generates and propagates cracks in the latter. Likewise, the composite shell of type IV tanks may be susceptible to fatigue due, e.g. to manufacturing defaults. To solve this issue, the present inventors have devised a method 100 for managing pressure within such a gas tank. The method according to the invention involves monitoring the strain on the gas tank, comparing the strain to a predetermined threshold and operating subsequent refueling accordingly. This method is equally applicable to type III or type IV tanks. For a gas tank in good (nominal) condition, refueling is normally operated at the standard / design pressure, i.e. to reach a tank pressure corresponding to the nominal working pressure Pnom. This is the standard fueling mode. The present method is typically carried out by a processing unit (or control unit) that may conventionally comprise a processor, a memory, interfaces, etc. The processing unit can be an independent controller or integrated within the Engine Control Unit (configured to control other functions / modules of the engine). According to the present method, if the strain is greater than a first predetermined threshold T1, subsequent refueling of the tank are operated such that the pressure within the tank does not exceed a predetermined maximum allowed pressure Fallowed, which is lower than the nominal working pressure Pnom for the gas tank. A flowchart representing an exemplary application of the inventive method is shown on figure 3 and detailed below. In an initial step the strain on the composite shell is monitored at S102. The strain in the gas tank may be determined by means of an optical fiber sensor embedded in the composite (or at the interface with the liner), as will be described below. The monitoring may imply continuous determination of the strain, or periodic determination at predetermined intervals. This strain value e is then compared to the first predetermined threshold T1 at S104. If the strain value e is lower than the first predetermined threshold T1, a low strain notification may be sent to the user or stored in a memory (control unit), S106. This low strain notification reflects the fact that the tank is under nominal working conditions; there is no reason for concern (the tank is not considered damaged). The refueling / filling is performed according to the standard mode, to reach a tank pressure that corresponds to Pnom. However, if the strain value s is greater than the first predetermined threshold T1, a subroutine is initiated, by which the maximum allowed pressure Paiiowed is defined S108(i.e. enabled or made activate) and by which subsequent refueling is operated such that the pressure within the tank Ptankdoes not exceed the maximum allowed pressure Paiiowed, step S110. As indicated before, Pailowed is lower than Pnom. By decreasing the maximum pressure at which the tank may be refueled, the amplitude of the pressure variations within the tank are reduced, thereby limiting possible metal fatigue behavior. Restriction of refueling may be performed by using mechanical means (e.g. a valve isolating the tank from a refueling line), or control means (e.g. by communicating a maximum refueling pressure to a gas station). The strain value e is then compared to a second predetermined threshold T2 which is higher than the first predetermined threshold T1, S112. If the strain value e is lower than the second predetermined threshold T2 (and higher than the first predetermined threshold T1), then a medium strain notification is sent to the user and / or registered in memory, step S114. This medium strain notification may inform the user that refueling of the tank is currently restricted, and may suggest the user to get the gas tank inspected. To sum up, when T1< £ <T2, the driver can still drive and refuel the car, however the target I maximum filling pressure is Fallowed. This tank pressure operating mode may be referred to as “faulty mode”, by contrast to the standard mode where the tank can be filled at Pnom. Now, if the strain value £ is greater than the second predetermined threshold T2, a high strain notification (S116) is sent to the user and / or registered in a memory; and a countdown is initiated (S118), at the end of which the engine is automatically shut down (S120). This operating mode may be referred to as “critical mode”. The high strain notification may inform the user that the gas tank is under critical condition and automatically route him to the nearest mechanic for inspection. The countdown may be based e.g. on distance, time, fuel quantity, or a combination thereof. In preferred embodiments, restart of the engine is restricted (S122) following the end of said countdown, e.g. the engine may only be restarted a set number of times, each restart incrementing a counter and triggering its own countdown. Once the set number of restart has been reached, further engine restarts are prevented, forcing the user to get their vehicle inspected. The values for thresholds T1 and T2 may be determined by calibration / experimentation, to prevent the formation of cracks in the liner and / or the composite shell due to fatigue. The value for Pallowed is then determined correspondingly, as the allowable pressure to operate in faulty mode, while limiting formation of cracks or propagation of existing ones. The threshold T1 and T2 as well as the pressure Paiiowed are predetermined for a given gas tank design and stored in a memory. The strain within the gas tank may typically be monitored by using an arrangement of strain sensing device enclosed or embedded within the composite shell. In particular, the arrangement of strain sensing device may employ an optical fiber 24 (shown on figure 2) embedded within the composite shell and functionalized as strain sensor, e.g. by means of Bragg Gratings. The strain in the composite shell may then be computed by introducing an incident light beam in the optical fiber at a predetermined frequency and / or wavelength, receiving a corresponding light beam from the optical fiber, determining the frequency and the wavelength of the received light beam, determining a frequency and / or a wavelength shift based on a difference between the frequency and wavelength of the received light beam and the predetermined frequency and wavelength of the incident light beam, and determining a strain within the composite shell from a stored mapping of strain against light frequency and wavelength shift. Hence, the step of monitoring the strain typically comprises determining strain within the composite shell based on a shift of frequency and / or wavelength of the output signal from the light receptor. The arrangement of strain sensing device may comprise a plurality of such optical fibers, e.g. two per gas tank, for the sake of redundancy of information. It may be noted that a same optical fiber can allow measuring strain at several location, by integrating Bragg gratings at predetermined locations in the optical fiber. The optical fibers may be advantageously arranged between the liner and the composite shell for type III tanks, or embedded within the shell for type IV tanks, preferably between the last (i.e. largest) polar winding of the composite shell and a subsequent helicoidal or circumferential winding. Additionally or alternatively, pressure within the gas tank may be estimated by using a similar method, and specifically the same optical fibers. More specifically, as described above, optical fiber with Bragg grating may be enclosed by or embedded within the composite shell and a frequency / wavelength shift may be determined based on a difference between frequency and wavelength of a received light beam and the predetermined frequency and wavelength of an incident light beam. This frequency / wavelength shift may then be used as input for a pre-trained neural network implemented by the ECU, which outputs a corresponding pressure estimate for the gas tank. Temperature within the gas tank may be alternatively or additionally monitored using means conventional in the art, e.g. by means of thermal sensor, e.g. integrated within a valve arrangement coupled to a boss of the gas tank. Figure 4 illustrates a flowchart of a method, indicated 200, for refueling a vehicle powered by gaseous fuel, implementing the method for managing pressure as described above. It is supposed that faulty mode is active, i.e. a medium strain condition has been measured and refueling is authorized at Paiiowed. When arriving at a fueling station, the driver will typically start a fueling procedure in the car’s interface (pressing a button) to achieve a coupling S202 of the vehicle with the fueling station. Such fueling procedure may comprise various steps, but typically open the fuel filler flap, connect the fueling nozzle to the tank, measure at least one of tank pressure and temperature, as well as activate communication means in order to communicate the in-tank pressure and / or temperature to the fueling station (S204). The knowledge of the initial tank pressure and temperature is conventionally required to configure the gas delivery within the fueling station. The tank pressure and temperature can be measured using conventional sensors. Tank pressure may also be measured based on optical fibers integrated in the tank, as explained above. Communication may be performed via short-range communication means from the gas tank, respectively vehicle, to the refueling station, e.g. by using a pair of infrared emitter and receptor. The infrared emitter may be arranged close to the fuel filler opening and the infrared receptor on the fueling nozzle. Alternatively communication between vehicle and refueling station can occur via Bluetooth or other. Gas is then delivered from the refueling station to the gas tank (S206), the delivery of gas being operated such that the tank pressure does not exceed the maximum allowed pressure, as previously explained. Two options are possible. The first option is illustrated in Fig.4. Ptank is monitored during refueling and compared to Paiiowed, S208. Fueling is carried out as long as Ptank <Paiiowed, if not voluntarily stopped by the driver. When the tank pressure Ptank reaches the maximum allowed pressure Paiiowed, the vehicle / gas tank then sends a request to the fueling station to end the delivery of gas (‘Abort’ instruction) (S210). Alternatively the vehicle / gas tank may communicate its Paiiowed to the refueling station, which then sets the maximum allowed pressure as target tank pressure for the delivering step. The actual pressure within the gas tank may fluctuate during refueling due to variation of temperatures or other thermodynamic processes. Said fluctuation of pressure are ignored in the inventive method because they are transitory and typically inferior to PBurst The maximum allowed pressure Paiiowed thus defines a maximum target refueling pressure for the tank, i.e. pressure within the tank after the gaseous has stabilized from the aforementioned fluctuations. After refueling, the fueling nozzle is decoupled from the vehicle and the fueling procedure is finished, S212. There are various ways the present method can be implemented in practice. In that context, Paiiowed represents a maximum filling / refueling pressure to be allowed for the gas tank. In embodiments, the refueling procedure may comprise the vehicle communicating to the refueling station a “target refueling pressure”. Such “target 5 refueling pressure” may be defined as the standard filling pressure, for a tank in nominal operating condition. That is, by default the target refueling pressure may be equal to the nominal working pressure (or another value for a nominal tank). As long as the strain level is still low, the target refueling pressure operates with the default value. In case the ‘faulty mode’ is active, the vehicle controller may update the target 10 refueling pressure to correspond to Fallowed. This is a simple to implement, since only one parameter needs to be transmitted to the refueling station. Alternatively, the refueling procedure may be configured such that the refueling station may receive from the vehicle a nominal target refueling pressure and, if fautly mode is active, Fallowed.

Claims

1. Computer-implemented method for managing pressure within a gas tank, wherein the gas tank comprises a liner defining a plenum chamber for the gas, a composite shell surrounding the liner, and an arrangement of strain sensing device embedded within the composite shell, the method comprising the steps of:- monitoring strain within the gas tank using data from the strain sensing device;- comparing the strain to a first predetermined threshold;- if the strain is greater than the first predetermined threshold, operating a in a faulty mode, by which subsequent refueling of the tank is performed such that the pressure within the tank does not exceed a predetermined maximum allowed pressure, which is lower than a nominal working pressure for the gas tank.

2. Computer-implemented method according to any of the preceding claims, wherein the strain is compared to a second predetermined threshold, the second predetermined threshold being higher than the first predetermined threshold; andwherein if the computed strain is higher than the second predetermined threshold, a countdown is initiated, at the end of which the engine is automatically shut down.

3. Computer-implemented method according to the preceding claim, wherein if the computed strain is higher than the second predetermined threshold, a command preventing the engine from being restarted is enabled.

4. Computer-implemented method according to the preceding claim, wherein if the strain is higher than the second predetermined threshold, a counter is incremented each time the engine is restarted, and wherein the command preventing the engine from being restarted is enabled if said counter reaches a predetermined value.

5. Computer-implemented method according to any of the preceding claims, wherein the strain and / or the result of the comparison with a predetermined threshold are stored and associated to a corresponding date and time.

6. Computer-implemented method according to any of the preceding claim, further comprising the step of notifying the user of the strain within the hydrogen tank based on the result of the comparison with a predetermined threshold.

7. Computer-implemented method according to any of the preceding claims, wherein the arrangement of strain sensing devices comprises at least one optical fiber, preferably two optical fibers, a light source configured to introduce light in said optical fiber, and a light receptor configured to receive light from said optical fiber and output a corresponding numerical signal; andwherein the step of monitoring the strain is performed using the output signal from the light receptor.

8. Computer-implemented method according to the preceding claim, wherein said optical fiber comprises one or more Bragg gratings.

9. Computer-implemented method according to claims 7 or 8, wherein the output signal of the light receptor is transmitted to a processing unit, which is configured to estimate a pressure within the gas tank from said output signal, preferably by implementing a trained neural network.

10. Computer-implemented method according to any of the preceding claims, wherein in faulty mode, the maximum allowed pressure is communicated to a refueling station during a refueling operation; or an abort instruction is sent to the refueling station when the in-tank pressure reaches the maximum allowed pressure.

11. Processing unit comprising instructions which, when executed, implement the method according to any of the preceding claims, preferably wherein the processing unit is an Engine Control Unit of a vehicle.

12. Fuel delivery system comprising a gas tank with a liner and a composite shell, an arrangement of strain sensing device, numerical communication means, and the processing unit according to claim 11;wherein the arrangement of strain sensing device is configured to measure strain on the gas tank and is connected to the processing unit.

13. Fuel delivery system according to claim 12, wherein the liner is a metallic liner or a plastic liner.

14. Method for refueling a gas tank of a vehicle at a refueling station, said method comprising the steps of:- communicating to the refueling station at least one of a tank pressure and tank temperature;- delivering a gas from the refueling station to the gas tank,- ending the delivery of gas if the tank pressure reaches the maximum allowed pressure defined by the method according to any one claims 1 to 10.

15. The method according to claim 14, wherein the tank pressure is measured during delivering, and wherein delivering is ended upon request by the gas tank, respectively vehicle, when the tank pressure reaches the maximum allowed pressure.

16. The method according to claim 14 or 15, comprisingcommunicating the maximum allowed pressure from the gas tank, respectively vehicle, to the refueling station;setting the refueling station to operate the delivering step at a maximum delivery pressure corresponding to the maximum allowed pressure.

17. The method according to any of claims 14 to 16, wherein communicating is performed via short-range communication means from the gas tank, respectively vehicle, to the refueling station.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS:-Claims1. Computer-implemented method for managing pressure within a gas tank, wherein the gas tank comprises a liner defining a plenum chamber for the gas, a composite shell surrounding the liner, and an arrangement of strain sensing device embedded within the composite shell, the method comprising the steps of:- monitoring strain within the gas tank using data from the strain sensing device;- comparing the strain to a first predetermined threshold;- if the strain is greater than the first predetermined threshold, the computer implemented method enters a faulty operation mode, whereby during subsequent refueling of the tank, a predetermined maximum allowed pressure is communicated to a refueling station, or an abort instruction is sent to the refueling station when the in-tank pressure, determined from a pressure sensor on the gas tank, reaches a predetermined maximum allowed pressure, thereby ensuring that the pressure within the tank does not exceed said predetermined maximum allowed pressure, which is lower than a nominal working pressure for the gas tank.

2. Computer-implemented method according to any of the preceding claims, wherein the strain is compared to a second predetermined threshold, the second predetermined threshold being higher than the first predetermined threshold; andwherein if the computed strain is higher than the second predetermined threshold, a countdown is initiated, at the end of which an engine is automatically shut down.

3. Computer-implemented method according to the preceding claim, wherein if the computed strain is higher than the second predetermined threshold, a command preventing the engine from being restarted is enabled.

4. Computer-implemented method according to the preceding claim, wherein if the strain is higher than the second predetermined threshold, a counter is incremented each time the engine is restarted, and wherein the command preventing the engine from being restarted is enabled if said counter reaches a predetermined value.

5. Computer-implemented method according to any of claims 2 to 4, wherein the strain and / or the result of the comparison with the second predetermined threshold are stored and associated to a corresponding date and time.

6. Computer-implemented method according to any of the preceding claims, wherein the strain and / or the result of the comparison with the first predetermined threshold are stored and associated to a corresponding date and time.

7. Computer-implemented method according to any of the preceding claim, further comprising the step of notifying the user of the strain within the gas tank based on the result of the comparison with a predetermined threshold.

8. Computer-implemented method according to any of the preceding claims, wherein the arrangement of strain sensing device comprises at least one optical fiber, a light source configured to introduce light in said optical fiber, and a light receptor configured to receive light from said optical fiber and output a corresponding numerical signal; andwherein the step of monitoring the strain is performed using the output signal from the light receptor.

9. Computer-implemented method according to the preceding claims, wherein the arrangement of strain sensing device comprises at least two optical fibers.

10. Computer-implemented method according to the preceding claim, wherein said optical fiber comprises one or more Bragg gratings.

11. Computer-implemented method according to any of claims 8 to 10, wherein the output signal of the light receptor is transmitted to a processing unit, which is configured to estimate a pressure within the gas tank from said output signal,12. Computer-implemented method according to the preceding claim, whereby the processing unit is configured to estimate a pressure within the gas tank from said output signal by implementing a trained neural network.

13. Processing unit comprising instructions which, when executed, implement the method according to any of the preceding claims.

14. Fuel delivery system comprising a gas tank with a liner and a composite shell, an arrangement of strain sensing device, numerical communication means, and the processing unit according to claim 13;wherein the arrangement of strain sensing device is configured to measure strain on the gas tank and is connected to the processing unit.

15. Fuel delivery system according to claim 14, wherein the liner is a metallic liner or a plastic liner.

16. Method for refueling a gas tank of a vehicle at a refueling station, said method comprising the steps of:- communicating to the refueling station at least one of a gas tank pressure and gas tank temperature;- delivering a gas from the refueling station to the gas tank,- ending the delivery of gas if the gas tank pressure reaches the maximum allowed pressure defined by the method according to any one claims 1 to 12.

17. The method according to claim 16, wherein the tank pressure is measured during delivering, and wherein delivering is ended upon request by the vehicle, when the tank pressure reaches the maximum allowed pressure.

18. The method according to claim 16 or 17, comprisingcommunicating the maximum allowed pressure from the vehicle to the refueling station;setting the refueling station to operate the delivering step at a maximum delivery pressure corresponding to the maximum allowed pressure.5 19. The method according to any of claims 16 to 18, wherein communicating isperformed via short-range communication means from the vehicle to the refueling station.26 11 24Application No: GB2314591.5Examiner: Dr Gemma CandyClaims searched: 1-17Date of search: 19 March 2024Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 1-17 CN 218494746 U (HUBEI SPECIAL EQUIPMENT INSPECTION AND TESTING INST) See fig 1, and translated description of background technique and detailed ways. X 1-17 US 2007 / 0159345 Al (SIROSH et al.) See figs 4,7, abstract and paras 38, 40-41, 43, 45-49. X 1-17 WO 2018 / 215038 Al (NEL HYDROGEN AS) See abstract, figs and description of fig 1. X 1-17 CA 2944902 Al (0NEH2 INC) See figs, abstract, and paras 46. X 1-17 US2019 / 0003647 Al (HONDA MOTOR CO LTD) See figs, abstract and at least paras 7-15, 18. A - EP 0892244 A2 (FIAT RICERCHE) A - CN 103994319 A (SHANGHAI COMPOSITE MATERIAL TECHNOLOGY CO LTD) A - CN 206264392 U (UNIV SHANDONG)Categories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of same category. before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:Search of GB, EP, WO &US patent documents classified in the following areas of the UKCX :Worldwide search of patent documents classified in the following areas of the IPC____________F17C; G01D; G01L______________________________________________The following online and other databases have been used in the preparation of this search report[SEARCH-PATENT], [SEARCH-NPL]International Classification:Subclass Subgroup Valid From GO IL 0011 / 02 01 / 01 / 2006 F17C 0005 / 00 01 / 01 / 2006 F17C 0005 / 06 01 / 01 / 2006 F17C 0013 / 02 01 / 01 / 2006 GO ID 0005 / 353 01 / 01 / 2006

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