Method, computer program, computer readable medium, control device and vehicle for estimating occurrence of fuel gas emission from a fuel gas system

Abstract

A method (100) for estimating the occurrence of fuel gas emissions from a fuel gas system (1) of a vehicle (2) is disclosed. The method (100) includes the following steps: during a shutdown phase (ph1) of the vehicle (2), storing (110) data representing the current time and date, the current pressure (pl) in a first pressure tank (3), and the current fuel level in the first pressure tank (3); obtaining (120) a first time estimate (t1) for estimating the start of emissions from a first pressure relief valve (rv1) based on the stored data and a model for the state of fuel gas in the first pressure tank (3); and after a parking period (Sp) of the vehicle (2), estimating (130) whether emissions from the first pressure relief valve (rv1) have started during the parking period (Sp) by checking whether the first time estimate (t1) was within the parking period (Sp). This disclosure also relates to a computer program, a computer-readable medium, a control device (21), and a vehicle (2).

Description

Technical Field

[0001] This disclosure relates to a method for estimating the occurrence of fuel gas emissions from a vehicle's fuel gas system, wherein the fuel gas system is configured to supply fuel gas to the vehicle's power source. This disclosure also relates to a computer program, a computer-readable medium, a control device configured to estimate the occurrence of fuel gas emissions from a vehicle's fuel gas system, and a vehicle including the control device. Background Technology

[0002] Fuel gas is any of a variety of fuels that are gases under normal ambient temperature and pressure conditions. Many fuel gases consist of hydrocarbons (methane, butane, or propane, or mixtures thereof). Some examples of different types of fuel gases are compressed natural gas (CNG), liquefied natural gas (LNG), and hydrogen (H2).

[0003] Specifically, trucks running on methane fuel are typically equipped with fuel systems that use compressed methane or cryogenic methane. This methane fuel can be derived from a variety of sources. When derived from fossil gas, it is called compressed natural gas (CNG) or liquefied natural gas (LNG). Alternatively, when derived from biological processes, such as manure, waste, or crops, it is called compressed biogas (CBG) or liquefied biogas (LBG).

[0004] The inherently low density of gaseous fuels poses a significant challenge to achieving sufficient vehicle range, a limitation less common in vehicles powered by gasoline or diesel. To address this, methane-fueled trucks are typically equipped with large tank systems that occupy a significant portion of the vehicle's side space to ensure adequate fuel capacity. An alternative approach to increasing range involves cooling the fuel to a cryogenic state, thereby increasing its density. In this context, methane is typically stored in the temperature range of -130°C to -120°C, while hydrogen requires even lower temperatures, below 250°C. Tanks designed for this purpose are cryogenic, effectively minimizing heat transfer from the surrounding environment to the fuel, thus maintaining the fuel in a two-phase state, comprising both liquid and gaseous states.

[0005] While these cryogenic storage tanks are effective in reducing heat gain, ambient temperatures inevitably cause the fuel to gradually warm. This process leads to a gradual increase in pressure within the tank. To address this, the system includes pressure relief valves configured to release fuel gases from the tank when the pressure exceeds a threshold pressure. For methane, this threshold pressure is typically 16 to 24 bar, while for hydrogen, the upper limit is slightly higher. These pressure relief valves play a crucial role in preventing excessive pressure buildup and ensuring the structural integrity of the tank.

[0006] As understood from the above description, unattended vehicles may release fuel gases into the atmosphere due to the inevitable transfer of heat from the surrounding environment to the fuel gases in the storage tanks. While methane is a viable fuel, it is also a potent greenhouse gas. Even seemingly small amounts of methane released into the atmosphere can have a significant impact on global warming. This is because methane has a higher global warming potential than carbon dioxide over a shorter timeframe.

[0007] Similarly, while hydrogen is not a greenhouse gas in its molecular form, it may have indirect environmental impacts. In the atmosphere, hydrogen interacts with hydroxyl radicals, which play a crucial role in the breakdown of methane (a significant greenhouse gas). An increase in atmospheric hydrogen could reduce these hydroxyl radicals. This reduction could indirectly allow methane to remain in the atmosphere for a longer period, potentially exacerbating global warming.

[0008] Furthermore, regardless of the specific type of fuel gas, releasing fuel gas into the atmosphere is an environmental problem because the fuel gas is wasted rather than used for beneficial purposes, such as powering vehicles.

[0009] When a parked vehicle is activated, it can be difficult to assess whether fuel gases have been released from one or more of the vehicle's storage tanks. Existing solutions utilize level sensors, which typically measure the dielectric properties of the fuel gases to infer their level. These dielectric properties differ between the liquid and gas phases, serving as the basis for assessing fuel level using these types of sensors. However, this approach has significant limitations because the accuracy of such level sensors is not always sufficient to definitively determine whether fuel gases have been released from the storage tank.

[0010] Currently, many vehicle owners and operators remain unaware of whether fuel gases are emitted from their vehicles while they are parked, and how much. This lack of awareness is particularly significant given the active involvement of many customers and users in environmental protection efforts. Understanding the extent of fuel gas emissions from their parked vehicles would be highly beneficial, aligning with their commitment to environmental responsibility. Furthermore, having this information would enable owners and operators to take necessary steps to prevent future fuel gas release into the atmosphere, thereby strengthening their environmental responsibility.

[0011] Furthermore, it is clear that releasing fuel gases into the atmosphere results in direct financial consequences due to the loss of valuable fuel resources. This unnecessary waste translates into increased operating costs for vehicle owners and operators. Summary of the Invention

[0012] The object of this invention is to overcome or at least mitigate some of the problems and disadvantages described above. This object is achieved by the subject matter of the appended independent claims.

[0013] According to a first aspect of this disclosure, this objective is achieved by a method for estimating the occurrence of fuel gas emissions from a vehicle's fuel gas system, wherein the fuel gas system is configured to supply fuel gas to a power source of the vehicle, and wherein the fuel gas system includes a first pressure tank and a first pressure relief valve, the first pressure relief valve being configured to begin discharging fuel gas from the first pressure tank when the pressure in the first pressure tank reaches or exceeds a first threshold pressure. The method includes the following steps: - During the vehicle's shutdown phase, store data representing the current time and date, the current pressure in the first pressure tank, and the current fuel level in the first pressure tank; - Based on the stored data and a model of the fuel gas state in the first pressure tank, obtain an estimate of the first time at which the first pressure relief valve begins to discharge; and After the parking period begins during the vehicle's engine shutdown phase: - Estimate whether the first pressure relief valve has started discharging during the shutdown period by checking whether the first time estimate is within the shutdown period.

[0014] Therefore, a method is provided that can estimate, in a simple and efficient manner, whether fuel gases have been emitted from the first pressure tank during a parking period. The estimation can be performed in a simple and efficient manner because the required data can be derived from existing sensors or systems in the vehicle and / or from inexpensive and uncomplicated sensors. Thus, a method is provided that can estimate whether fuel gases have been emitted from the first pressure tank during a parking period without significantly increasing the complexity or cost of the vehicle.

[0015] In other words, a method is provided to generate estimates that can be used to inform owners and operators, enabling them to take necessary measures to prevent future fuel gas emissions into the atmosphere. As a further result, conditions are provided that allow owners and operators to enhance their environmental responsibility and reduce their operating costs without significantly increasing vehicle complexity or cost.

[0016] Therefore, a method is provided that overcomes or at least mitigates some of the problems and disadvantages mentioned above. Thus, the objectives mentioned above are achieved.

[0017] Optionally, the step of obtaining a first-time estimate may be performed during the vehicle's start-up phase.

[0018] Therefore, a method is provided that reduces the need for data processing and computation during the vehicle's shutdown phase, thereby enabling reduced energy use during the shutdown phase and shortening the waiting time before the electrical shutdown of the vehicle's control devices is executed. Furthermore, a method is provided that provides conditions for inputting more accurate data into a model of the fuel gas state in the first pressure tank.

[0019] Optionally, the step of estimating whether the first pressure relief valve has started discharging is performed during the vehicle's start-up phase.

[0020] This provides a method to reduce the need for data processing and calculations during vehicle downtime. Furthermore, it provides a method for informing owners and operators during the vehicle startup phase whether it is estimated that fuel gases have been released from the first pressure tank during vehicle downtime. This allows them to take necessary measures to prevent future fuel gas release into the atmosphere.

[0021] Optionally, the method includes the following steps: Input the temperature data estimates into the model, where the temperature data estimates are representative estimated ambient temperatures during the stopover period.

[0022] This provides a method for offering a more accurate and reliable estimate of whether the first pressure relief valve has begun to discharge during a period of inactivity. This is because the ambient temperature during the inactivity period affects the risk of fuel gas emissions from the vehicle's fuel gas system.

[0023] Optionally, the method includes the following steps: - Input the fuel gas composition estimate into the model, where the fuel gas composition estimate represents the estimated composition of the fuel gas in the first pressure tank during the vehicle's shutdown phase.

[0024] This provides a method for offering a more accurate and reliable estimate of whether the first pressure relief valve has begun to discharge during a standstill. This is because the composition of the fuel gas in the first pressure tank during the vehicle's shutdown phase affects the risk of emissions from the fuel gas system of a fuel gas vehicle.

[0025] Optionally, the vehicle includes an input unit that enables a user to input an estimated value of fuel gas composition, and the step of inputting the estimated value of fuel gas composition includes the following steps: - Input the estimated fuel gas composition from the input cell into the model.

[0026] Optionally, the method includes the following steps: if the initial estimate falls within the dwell period, then: - Calculate the duration of the time interval between the first time estimate and the end of the dwell period; and - Estimate the amount of fuel gas discharged through the first pressure relief valve during the standby period based on the stored data, model, and duration of the time period.

[0027] Therefore, a method is provided that can estimate the amount of fuel gas emitted via the first pressure relief valve during a parking period in a simple and efficient manner. As described above, the estimation can be performed in a simple and efficient manner because the required data can be derived from existing sensors or systems in the vehicle and / or from inexpensive and uncomplicated sensors. Thus, a method is provided that can estimate the amount of fuel gas emitted from the first pressure tank during a parking period without significantly increasing the complexity or cost of the vehicle.

[0028] Furthermore, a method is provided to generate estimates that can be used to inform owners and operators of the amount of fuel gases emitted, enabling them to take necessary steps to reduce future fuel gas emissions into the atmosphere. As a further result, improved conditions are provided to enhance environmental responsibility and reduce operating costs for owners and operators without significantly increasing vehicle complexity or cost.

[0029] Optionally, the method includes performing the following steps during the vehicle's start-up phase: -Measure the pressure in the first pressure tank; and - The accuracy of the estimate of whether the first pressure relief valve has started discharging during the pause period is determined based on the measured pressure.

[0030] Therefore, the accuracy of the estimate regarding whether the first pressure relief valve has begun discharging during the inactivity period can be determined in a simple and effective manner. As mentioned above, the accuracy of the estimate can be determined in a simple and effective manner because the required data can be derived from the vehicle's existing sensors or systems and / or from inexpensive and uncomplicated sensors.

[0031] Optionally, the method includes the following steps: - If the determined accuracy is lower than the threshold accuracy, then update at least one parameter of the model.

[0032] Therefore, a method is provided that has conditions for adjusting and providing for improving future estimates of whether fuel gas has been discharged from the first pressure tank.

[0033] Optionally, the method includes performing the following steps during the vehicle's start-up phase: -Measure the pressure in the first pressure tank; and - If the measured pressure is outside the predetermined pressure range and the initial estimate is within the dwell period, a first-type error code is generated.

[0034] Therefore, a method is provided with conditions for generating data that can be used to perform simple and effective diagnostics on the operation of a vehicle's fuel gas system, including the operation of the first pressure relief valve of the fuel gas system. Furthermore, a method is provided with conditions for generating data that can be used to adjust and improve future estimates of whether fuel gas has been discharged from the first pressure tank.

[0035] Optionally, the method includes performing the following steps during the vehicle's start-up phase: -Measure the pressure in the first pressure tank; and - If the measured pressure is within the predetermined pressure range and the initial estimate is not within the dwell period, a second type of error code is generated.

[0036] Therefore, a method is provided with conditions for generating data that can be used to perform simple and effective diagnostics on the operation of a vehicle's fuel gas system, including the operation of the first pressure relief valve of the fuel gas system. Furthermore, a method is provided with conditions for generating data that can be used to adjust and improve future estimates of whether fuel gas has been discharged from the first pressure tank.

[0037] As used in this article, the terms "Type 1 error code" and "Type 2 error code" mean that Type 2 error codes can be distinguished from Type 1 error codes, and vice versa.

[0038] Optionally, the fuel gas system includes: a supply conduit configured to supply fuel gas from a first pressure tank to a power source of the vehicle; a pressure sensor configured to measure pressure in the supply conduit; and a first valve controllable between an open and closed state to open and close a fluid connection between the first pressure tank and the supply conduit, wherein the method includes the following steps: -During the vehicle start-up phase, the first valve is controlled to the open state, and the step of measuring the pressure in the first pressure tank includes the following steps: - Input data from the pressure sensor.

[0039] Therefore, a method is provided to measure the pressure in a first pressure tank using data from existing sensors in the vehicle and / or from inexpensive and uncomplicated sensors. Furthermore, in embodiments where the fuel gas system includes more than one pressure tank, the need to arrange multiple pressure sensors is avoided.

[0040] Optionally, the fuel gas system includes a pressure sensor configured to provide data representing the current pressure in the first pressure tank, and the step of storing the data during the vehicle's shutdown phase includes the following steps: - Stores data from the pressure sensor.

[0041] Therefore, reliable and accurate data representing the current pressure in the first pressure tank can be stored during the vehicle's engine shutdown phase. As a further result, conditions are provided for performing a more accurate estimate of whether fuel gases have been discharged from the first pressure tank.

[0042] Optionally, the fuel gas system includes a first level sensor configured to provide data representing the current fuel level in the first pressure tank, and wherein the step of storing the data during the vehicle's shutdown phase includes the following steps: - Store data from the first liquid level sensor.

[0043] Therefore, data representing the current fuel level in the first pressure tank can be stored in a simple and efficient manner during the vehicle's shutdown phase.

[0044] Optionally, the fuel gas system includes a second pressure tank and a second pressure relief valve, the second pressure relief valve being configured to begin discharging fuel gas from the second pressure tank when the pressure in the second pressure tank reaches or exceeds a second threshold pressure, wherein the method includes the following steps: - During the vehicle's shutdown phase, store data representing the current pressure in the second pressure tank and the current fuel level in the second pressure tank; - Based on the stored data and a model of the fuel gas state in the second pressure tank, obtain a second time estimate for when the second pressure relief valve begins to discharge; and After the parking period begins during the vehicle's engine shutdown phase: - Estimate whether the second pressure relief valve has started discharging during the standby period by checking whether the second time estimate is within the standby period.

[0045] Therefore, a method is provided that can estimate, in a simple and efficient manner, whether fuel gases have been emitted from the first and second pressure tanks during a parking period. As described above, the estimation can be performed in a simple and efficient manner because the required data can be derived from existing sensors or systems in the vehicle and / or from inexpensive and uncomplicated sensors. Thus, a method is provided that can estimate whether fuel gases have been emitted from the first and second pressure tanks during a parking period without significantly increasing the complexity or cost of the vehicle.

[0046] Optionally, the fuel gas system includes: a supply conduit configured to supply fuel gas from each of a first pressure tank and a second pressure tank to a power source of the vehicle; a first valve controllable between an open state and a closed state to open and close a fluid connection between the first pressure tank and the supply conduit; and a second valve controllable between an open state and a closed state to open and close a fluid connection between the second pressure tank and the supply conduit, wherein the method includes the following steps: - If the first time estimate is earlier than the second time estimate, then the first valve is opened before the second valve is opened; and - If the first time estimate is after the second time estimate, then the second valve is opened before the first valve is opened.

[0047] This provides the means to generate error codes and / or determine the accuracy of estimates of whether the pressure relief valve has begun discharging during the parking period, without significantly increasing the cost or complexity of the vehicle. This is because a pressure sensor arranged to sense the current pressure in the supply line can be used to determine, after the parking period, the current pressure in the first and second pressure tanks that is most likely to have discharged fuel gas from its pressure relief valve during the parking period.

[0048] According to a second aspect of this disclosure, this objective is achieved by a computer program comprising instructions to cause a control device according to the second aspect of this disclosure to perform steps of a method according to some embodiments of the first aspect of this disclosure. Since the computer program includes instructions to cause the control device to perform a method according to some embodiments described herein, a computer program is provided that provides conditions for overcoming or at least mitigating at least some of the disadvantages mentioned above. Therefore, the objective mentioned above is achieved.

[0049] According to a third aspect of this disclosure, this objective is achieved by a computer-readable medium storing a computer program according to a second aspect of this disclosure. Since the computer-readable medium includes instructions for causing a control device to perform methods according to some embodiments described herein, a computer-readable medium is provided that provides conditions for overcoming or at least mitigating at least some of the disadvantages mentioned above. Thus, the aforementioned objective is achieved.

[0050] According to a fourth aspect of this disclosure, this objective is achieved by a control device configured to estimate the occurrence of fuel gas emissions from a vehicle's fuel gas system, wherein the fuel gas system is configured to supply fuel gas to a power source of the vehicle, and wherein the fuel gas system includes a first pressure tank and a first pressure relief valve, the first pressure relief valve being configured to begin discharging fuel gas from the first pressure tank when the pressure in the first pressure tank reaches or exceeds a first threshold pressure, wherein the control device is configured to: - During the vehicle's shutdown phase, store data representing the current time and date, the current pressure in the first pressure tank, and the current fuel level in the first pressure tank; - Based on the stored data and a model of the fuel gas state in the first pressure tank, obtain an estimate of the first time at which the first pressure relief valve begins to discharge; and After the parking period begins during the vehicle's engine shutdown phase: - Estimate whether the first pressure relief valve has started discharging during the shutdown period by checking whether the first time estimate is within the shutdown period.

[0051] Therefore, a control device is provided that can estimate, in a simple and effective manner, whether fuel gases have been emitted from the first pressure tank during a parking period. The estimation can be performed in a simple and effective manner because the required data can be derived from existing sensors or systems in the vehicle and / or from inexpensive and uncomplicated sensors. Thus, a control device is provided that can estimate whether fuel gases have been emitted from the first pressure tank during a parking period without significantly increasing the complexity or cost of the vehicle.

[0052] In other words, a control device is provided that can generate estimates that can be used to inform owners and operators, enabling them to take necessary measures to prevent future emissions of fuel gases into the atmosphere. As a further result, conditions are provided that allow owners and operators to enhance their environmental responsibility and reduce their operating costs without significantly increasing the complexity or cost of the vehicle.

[0053] Therefore, a control device is provided that overcomes or at least mitigates some of the aforementioned problems and disadvantages. Thus, the objectives mentioned above are achieved.

[0054] It should be understood that all the various embodiments described for this method can be combined with the control device as described herein. That is, the control device according to the fourth aspect of the invention can be configured to perform any of the method steps of the method according to the first aspect of the invention.

[0055] According to a fifth aspect of this disclosure, the objective is achieved by a vehicle including a power source and a fuel gas system configured to supply fuel gas to the power source, wherein the fuel gas system includes a first pressure tank and a first pressure relief valve configured to begin discharging fuel gas from the first pressure tank when the pressure in the first pressure tank reaches or exceeds a first threshold pressure, and wherein the vehicle includes control devices according to a fourth aspect of this disclosure.

[0056] Since the vehicle includes the control device according to the fourth aspect of this disclosure, a vehicle including the control device is provided, which is capable of estimating in a simple and efficient manner whether fuel gas has been discharged from the first pressure tank during the vehicle's parking period.

[0057] As described above, estimation can be performed in a simple and efficient manner because the required data can be derived from existing sensors or systems in the vehicle and / or from inexpensive and uncomplicated sensors. Therefore, a vehicle including a control device is provided that can estimate whether fuel gases have been discharged from the first pressure tank during a parking period without significantly increasing the complexity or cost of the vehicle.

[0058] In other words, a vehicle is provided that has features enabling owners and operators to take necessary measures to prevent future emissions of fuel gases into the atmosphere. As a further result, features are provided that enable owners and operators to enhance their environmental responsibility and reduce their operating costs without significantly increasing the complexity or cost of the vehicle.

[0059] Therefore, a vehicle is provided that overcomes or at least mitigates some of the problems and disadvantages mentioned above. Thus, the objectives mentioned above are achieved.

[0060] Optionally, the first pressure tank is a cryogenic storage tank, which is configured to store fuel gas at least partially in liquid form and at a temperature below ambient temperature. Thus, a vehicle is provided having features for storing fuel gas in a space-saving manner, while including a control device capable of easily and effectively estimating whether fuel gas has been released from the cryogenic storage tank during periods of vehicle inactivity.

[0061] Optionally, the vehicle is a heavy-duty road vehicle, such as a truck or a bus. Thus, a heavy-duty road vehicle having at least some of the advantages described above is provided.

[0062] Further features and advantages of the invention will become apparent when examined in light of the appended claims and the following detailed description. Attached Figure Description

[0063] Various aspects of this disclosure, including its particular features and advantages, will be readily understood from the exemplary embodiments discussed in the following detailed description and accompanying drawings, wherein: Figure 1 The illustrations represent vehicles according to some implementation schemes. Figure 2 An illustrative example Figure 1 The illustrated vehicle's fuel gas system and power source, Figure 3 Examples include a horizontal axis showing time and an axis showing... Figure 2 The illustrated graph shows the vertical axis curves of the current pressure in the first and second pressure tanks of the fuel gas system. Figure 4 A method for estimating the generation of fuel gas emissions from a vehicle's fuel gas system is illustrated schematically, and Figure 5 Examples of computer-readable media are shown. Detailed Implementation

[0064] The various aspects of this disclosure will now be described more fully. Similar reference numerals always refer to similar elements. For the sake of brevity and / or clarity, well-known functions or constructions will not be described in detail.

[0065] Figure 1 Vehicle 2 is illustrated schematically according to some embodiments. According to the illustrated embodiments, vehicle 2 is a truck, i.e., a heavy-duty road vehicle.

[0066] According to another implementation scheme, as mentioned herein, vehicle 2 can be another type of heavy or lighter manned or unmanned vehicle used for land-based or water-based propulsion, such as trucks, buses, construction vehicles, tractors, automobiles, ships, boats, etc.

[0067] Vehicle 2 includes a power source 30. According to the illustrated embodiment, the power source 30 is configured to provide power to vehicle 2 via wheels 47. According to another embodiment, the power source 30 may be configured to provide power to the vehicle via another type of propulsion device. Vehicle 2 also includes a fuel gas system 1. The fuel gas system 1 is configured to supply fuel gas to the power source 30 of vehicle 2. The fuel gas system 1 may also be referred to as a fuel gas supply device. Figure 1 In the image, we can see the first pressure tank 3 and the second pressure tank 5 of the fuel gas system 1.

[0068] Figure 2 An illustrative example Figure 1 The illustrated vehicle 2 has a fuel gas system 1 and a power source 30. Unless otherwise indicated below, reference is also made to... Figure 1 and Figure 2Also in Figure 2 In the diagram, a first pressure tank 3 and a second pressure tank 5 of the fuel gas system 1 can be seen. Each of the first pressure tank 3 and the second pressure tank 5 is configured to store fuel gas at a pressure higher than ambient pressure. According to the illustrated embodiment, the fuel gas system 1 of the vehicle 2 includes two pressure tanks 3 and 5. However, according to another embodiment, the fuel gas system 1 of the vehicle 2 may include another number of pressure tanks 3 and 5, such as one, three, four, five, or six pressure tanks.

[0069] According to the illustrated embodiment, each of the first pressure tank 3 and the second pressure tank 5 is a cryogenic storage tank, configured to store fuel gas at least partially in liquid form and at temperatures below ambient temperature (such as approximately -130 degrees Celsius). Furthermore, each of the first pressure tank 3 and the second pressure tank 5 may be configured to store fuel gas in the form of liquefied natural gas (commonly abbreviated as LNG). Therefore, the first pressure tank 3 and the second pressure tank 5, as mentioned herein, may also be referred to as a first cryogenic storage tank and a second cryogenic storage tank, a first cryogenic fuel tank and a second cryogenic fuel tank, a first cryogenic pressure tank and a second cryogenic pressure tank, a first liquefied natural gas tank and a second liquefied natural gas tank, etc.

[0070] The fuel gas system 1 includes a first pressure relief valve rv1, which is configured to begin discharging fuel gas from the first pressure tank 3 when the pressure in the first pressure tank 3 reaches or exceeds a first threshold pressure. Similarly, the fuel gas system 1 includes a second pressure relief valve rv2, which is configured to begin discharging fuel gas from the second pressure tank 5 when the pressure in the second pressure tank 5 reaches or exceeds a second threshold pressure. By way of example only, each of the first and second threshold pressures may be in the range of 6 bar to 400 bar, or 6 bar to 700 bar.

[0071] When the pressure in pressure tanks 3 and 5 reaches or exceeds the corresponding threshold pressure, each of the first pressure relief valve rv1 and the second pressure relief valve rv2 prevents excessive pressure buildup in the corresponding pressure tank by discharging fuel gas from the corresponding pressure tank 3 or 5. In this way, damage to pressure tanks 3 and 5, as well as dangerous situations caused by excessive pressure inside pressure tanks 3 and 5, can be avoided.

[0072] The fuel gas system 1 includes a fuel supply conduit 7 connected to each of the first pressure tank 3 and the second pressure tank 5. The fuel supply conduit 7 may also be referred to as a fuel gas supply conduit 7. More specifically, the fuel gas system 1 includes a first branch conduit 7' connecting the first pressure tank 3 to the fuel supply conduit 7 and a second branch conduit 7' connecting the second pressure tank 5 to the fuel supply conduit 7. Each of the first branch conduit 7' and the second branch conduit 7' is connected to the fuel supply conduit 7 at a T-joint 17 of the fuel gas system 1. The fuel supply conduit 7 is arranged to guide fuel gas from each of the first pressure tank 3 and the second pressure tank 5 in a direction toward the power source 30, as further explained herein.

[0073] The fuel gas system 1 also includes a first valve v1 disposed between the first pressure tank 3 and the fuel supply line 7, and a second valve v2 disposed between the second pressure tank 5 and the fuel supply line 7. According to the illustrated embodiment, each of the first valve v1 and the second valve v2 is a so-called shut-off valve for cutting off (i.e., closing) the corresponding pressure tanks 3 and 5 when the vehicle 2, including the fuel supply line 7, is not in operation. Each of the first valve v1 and the second valve v2 may include a solenoid.

[0074] As in Figure 2 As can be seen, according to the illustrated embodiment, the first valve v1 is arranged on the first pressure tank 3, and the second valve v2 is arranged on the second pressure tank 5. Therefore, according to the illustrated embodiment, the first valve v1 is arranged between the first pressure tank 3 and the first branch pipe 7', and the second valve v2 is arranged between the second pressure tank 5 and the second branch pipe 7'".

[0075] Each of the first valve v1 and the second valve v2 can be controlled between an open state and an open state, including an open state and a closed state. The first valve v1 is configured to prevent fuel gas from flowing from the first pressure tank 3 into the first branch pipe 7' when it is in the closed state, and thereby also prevent fuel gas from flowing into the fuel supply pipe 7, and is configured to allow fuel gas from the first pressure tank 3 into the first branch pipe 7' when it is in the open state, and thereby also allow fuel gas to flow into the fuel supply pipe 7 through the T-connector 17. Similarly, the second valve v2 is configured to prevent fuel gas from flowing from the second pressure tank 5 into the second branch pipe 7'" when it is in the closed state, and thereby also prevent fuel gas from flowing into the fuel supply pipe 7, and is configured to allow fuel gas from the second pressure tank 5 into the second branch pipe 7'" when it is in the open state, and thereby also allow fuel gas to flow into the fuel supply pipe 7 through the T-connector 17.

[0076] According to the illustrated embodiment, the fuel gas system 1 includes a fuel gas processing unit 14. The fuel gas processing unit 14 may be referred to as a gas panel. According to the illustrated embodiment, the fuel gas processing unit 14 includes a fuel pressure regulator 16 and a fuel filter 19. The fuel pressure regulator 16 may also be referred to as a regulator, pressure adjuster, etc., and is configured to reduce the pressure of the fuel gas before it is directed to the inlet 31 of the power source 30.

[0077] According to the illustrated embodiment, the power source 30 is an internal combustion engine configured to operate on fuel gas supplied from the fuel gas system 1 to the power source 30. The fuel filter 19 is configured to filter the fuel gas before it is directed to the inlet 31 of the power source 30, i.e., to separate particulate matter and unwanted substances from the fuel gas.

[0078] According to another embodiment, vehicle 2 may include another type of power source configured to power vehicle 2 using fuel gas from the first pressure tank 3 and the second pressure tank 5 of fuel gas system 1. One example is a fuel cell system capable of directly converting the chemical energy from fuel gas (such as hydrogen) into electrical energy through a chemical reaction with oxygen. This electricity can then power multiple electric motors of vehicle 2 to provide their prime mover.

[0079] like Figure 2 As seen, the fuel supply conduit 7 is connected to the fuel gas processing unit 14. In other words, the fuel supply conduit 7 is configured to guide fuel gas from each of the first pressure tank 3 and the second pressure tank 5 to the fuel gas processing unit 14.

[0080] As mentioned, according to the illustrated embodiment, each of the first pressure tank 3 and the second pressure tank 5 is a cryogenic storage tank, which is configured to store fuel gas at least partially in liquid form and at a temperature below ambient temperature. Components of the fuel gas processing unit 14 and the power source 30 are sensitive to fuel gas supply sources with excessively low temperatures.

[0081] According to the illustrated embodiment, the fuel gas system 1 includes a first heat exchanger 11 configured to heat fuel gas flowing from a first pressure tank 3 to a fuel supply line 7. Furthermore, the fuel gas system 1 includes a second heat exchanger 12 configured to heat fuel gas flowing from a second pressure tank 5 to the fuel supply line 7. According to the illustrated embodiment, the first heat exchanger 11 is disposed on the first pressure tank 3, and the second heat exchanger 12 is disposed on the second pressure tank 5.

[0082] According to the illustrated embodiment, the power source 30 includes a cooling system 32 configured to cool the power source 30 during operation. The cooling system 32 of the power source 30 includes a radiator 34 configured to transfer heat from the coolant in the cooling system 34 to the surrounding environment. The radiator 34 may, for example, be mounted at the front of a vehicle including the power source 30.

[0083] According to the illustrated embodiment, each of the first heat exchanger 11 and the second heat exchanger 12 is configured to use the heat of the coolant in the cooling system 32 of the power source 30 to heat the fuel gas. That is, according to the illustrated embodiment, the fuel gas system 1 includes a coolant circuit 36 ​​that connects each of the first heat exchanger 11 and the second heat exchanger 12 to the cooling system 32 of the power source 30.

[0084] In this way, each of the first heat exchanger 11 and the second heat exchanger 12 can use heat from the coolant in the cooling system 32 of the power source 30 to heat the fuel gas from the first pressure tank 3 and the second pressure tank 5, respectively. Alternatively or otherwise, each of the first heat exchanger 11 and the second heat exchanger 12 can use heat from another type of system or device (such as from an electric heater) to heat the fuel gas from the first pressure tank 3 and the second pressure tank 5, respectively.

[0085] according to Figure 2 In the illustrated embodiment, the coolant in the coolant circuit 36 ​​heats the first heat exchanger 11 and the second heat exchanger 12 in parallel. According to another embodiment, the coolant in the coolant circuit 36 ​​can heat the first heat exchanger 11 and the second heat exchanger 12 connected in series.

[0086] According to the illustrated embodiment, the fuel gas system 1 includes a first level sensor L1. The first level sensor L1 is configured to provide data indicating the current fuel level in the first pressure tank 3. Furthermore, according to the illustrated embodiment, the fuel gas system 1 includes a second level sensor L2. The second level sensor L2 is configured to provide data indicating the current fuel level in the second pressure tank 5.

[0087] Each of the first level sensor L1 and the second level sensor L2 can be configured to measure the dielectric properties of the fuel gas in the respective pressure tanks 3 and 5 to provide data representing the current fuel level in the pressure tanks 3 and 5. Each of the first level sensor L1 and the second level sensor L2 may include two conductive plates (commonly referred to as electrodes) placed within the respective pressure tanks 3 and 5, with the fuel gas in the pressure tanks 3 and 5 serving as the dielectric between them. Furthermore, the first... Each of the level sensor L1 and the second level sensor L2 operates based on the principle of capacitance change caused by variations in the dielectric constant of the medium surrounding its electrodes (i.e., fuel gas). When the fuel level in pressure tanks 3 and 5 changes, the ratio of the electrode immersed in the liquid phase to the electrode immersed in the gas phase changes. Since the liquid and gas phases have different dielectric constants, this change affects the capacitance measured between the plates.

[0088] like Figure 2 As indicated, the fuel gas system 1 includes a pressure sensor 15. According to the illustrated embodiment, the pressure sensor 15 is configured to sense the pressure of the fuel gas in the fuel supply conduit 7. Furthermore, as in... Figure 2 As can be seen, according to the illustrated embodiment, pressure sensor 15 is arranged on fuel gas processing unit 14. Pressure sensor 15 is located downstream of T-connector 17 and upstream of fuel pressure regulator 16 and fuel filter 19 of fuel gas processing unit 14. In this way, pressure sensor 15 is able to directly sense the pressure representing the pressure of fuel gas inside fuel supply pipe 7. However, according to another embodiment, fuel gas system 1 may include a pressure sensor located at another part of fuel supply pipe 7.

[0089] The fuel gas system 1 includes a control device 21. According to the illustrated embodiment, the control device 21 is operatively connected to a first valve v1 and a second valve v2, a first liquid level sensor L1 and a second liquid level sensor L2, a pressure sensor 15, a vehicle 2 control system 21', and a memory 23.

[0090] As further explained herein, control device 21 is configured to estimate the occurrence of fuel gas emissions from fuel gas system 1 of vehicle 2. More specifically, according to embodiments herein, control device 21 is configured to store data in memory 23 during the engine shutdown phase of vehicle 2, wherein the data represents the current time and date, the current pressure p1 in the first pressure tank 3, the current pressure p2 in the second pressure tank 5, the current fuel level in the first pressure tank 3, and the current fuel level in the second pressure tank 5. Memory 23 may be included in control device 21, in control system 21' of vehicle 2, in another part of vehicle 2, in equipment or system, or in equipment or system external to vehicle 2.

[0091] The control device 21 may be configured to obtain the current time and date from an on-board system (such as from the control system 21' of the vehicle 2), or may be configured to obtain the current time and date from a device or system outside the vehicle 2.

[0092] The control device 21 can be configured to obtain data representing the current pressure p1 in the first pressure tank 3 and the current pressure p2 in the second pressure tank 5 by inputting data from the pressure sensor 15.

[0093] The control device 21 can be configured to obtain data representing the current fuel level in the first pressure tank 3 by inputting data from the first level sensor L1, and can be configured to obtain data representing the current fuel level in the second pressure tank 5 by inputting data from the second level sensor L2.

[0094] Figure 3 The diagram illustrates a graph with horizontal and vertical axes. The horizontal axis represents time t, and the vertical axes represent the current pressures p1 and p2 in the first pressure tank 3 and the second pressure tank 5, respectively. Unless otherwise indicated, reference will be made to the following text. Figures 1 to 3 .

[0095] exist Figure 3 The text indicates the engine shutdown phase ph1 of vehicle 2 and the parking period Sp of vehicle 2. The parking period Sp lasts from the beginning 81 of the parking period Sp to the end 82 of the parking period Sp. The parking period Sp can last, for example, several hours or several days.

[0096] As can be seen, the pressures P1 and P2 in the corresponding first pressure tank 3 and second pressure tank 5 decrease slightly during the period until the start of the parking period Sp 81. This is because vehicle 2 continues to operate until the start of the parking period Sp 81, and fuel gas is consumed from each of the first pressure tank 3 and second pressure tank 5.

[0097] When the control unit 21 receives a vehicle deactivation request, it initiates the engine shutdown phase ph1. The control unit 21 may be configured to receive the vehicle deactivation request from an input unit arranged in the driver environment 40 of the vehicle 2 or from another type of device or system of the vehicle 2 (such as at least part of the autonomous driving system of the vehicle 2).

[0098] As mentioned, according to the illustrated embodiment, control device 21 is configured to store data representing the current time and date, the current pressure p1 in the first pressure tank 3, the current pressure p2 in the second pressure tank 5, the current fuel level in the first pressure tank 3, and the current fuel level in the second pressure tank 5 during the vehicle 2's shutdown phase ph1. Control device 21 may be configured to store the aforementioned data upon receiving a vehicle deactivation request.

[0099] Furthermore, control device 21 can be configured to control each of the first valve v1 and the second valve v2 to a corresponding closed state in response to receiving a vehicle deactivation request. Control device 21 can be configured to control each of the first valve v1 and the second valve v2 to a corresponding closed state after storing the aforementioned data or in combination with storing the aforementioned data. Controlling each of the first valve v1 and the second valve v2 to a corresponding closed state can trigger... Figure 3 The pause period Sp indicated in the text begins at 81.

[0100] exist Figure 3 The text indicates the start-up phase ph2 of vehicle 2. When control device 21 receives a vehicle activation request, it initiates the start-up phase ph2 of vehicle 2. Control device 21 can be configured to receive the vehicle activation request from an input unit arranged in the driver environment 40 of vehicle 2 or from another type of device or system of vehicle 2 (such as at least part of the autonomous driving system of vehicle 2).

[0101] According to the embodiments described herein, control device 21 is configured to obtain a first estimated time t1 for the start of discharge from the first pressure relief valve rv1 based on stored data and a model of the fuel gas state in the first pressure tank 3. Furthermore, according to the illustrated embodiments, control device 21 is configured to obtain a second estimated time t2 for the start of discharge from the second pressure relief valve rv2 based on stored data and a model of the fuel gas state in the second pressure tank 5.

[0102] The control device 21 can be configured to obtain a first time estimate t1 by calculating a first time estimate t1 based on stored data and a model of the state of fuel gas in the first pressure tank 3. Similarly, the control device 21 can be configured to obtain a second time estimate t2 by calculating a second time estimate t2 based on stored data and a model of the state of fuel gas in the second pressure tank 5.

[0103] According to the illustrated embodiment, control device 21 is configured to obtain a first time estimate t1 and a second time estimate t2 during the vehicle 2 start-up phase ph2 (i.e., in response to a vehicle activation request). However, according to another embodiment, control device 21 may be configured to obtain one or both of the first time estimate t1 and the second time estimate t2 during the engine shutdown phase ph1 or during the parking period Sp.

[0104] The control device 21 is also configured to: after the dwell time Sp, estimate whether the first pressure relief valve rv1 has started discharging during the dwell time by checking whether the first time estimate t1 is within the dwell time. Furthermore, according to the illustrated embodiment, the control device 21 is configured to: after the dwell time Sp, estimate whether the second pressure relief valve rv2 has started discharging during the dwell time by checking whether the second time estimate t2 is within the dwell time.

[0105] Thus, control device 21 can estimate in a simple and efficient manner whether fuel gas has been discharged from one or both of the first pressure tank 3 and the second pressure tank 5 during the parking period Sp, as further explained herein. According to the illustrated embodiment, control device 21 is configured to perform an estimation of whether the first pressure relief valve rv1 has started discharging during the vehicle 2 start-up phase ph2 (i.e., upon receiving a vehicle activation request), and to perform an estimation of whether the second pressure relief valve rv2 has started discharging.

[0106] exist Figure 3 In the illustrated example, the pressure p1 in the first pressure tank 3 increases during the time interval between the start of the dwell period Sp 81 and the first time estimate t1, and the pressure p2 in the second pressure tank 5 increases during the time interval between the start of the dwell period Sp 81 and the second time estimate t2. Figure 1 and Figure 2 As seen, the first pressure tank 3 is smaller than the second pressure tank 5. Therefore, the fuel gas in the first pressure tank 3 experiences a faster temperature rise compared to the fuel gas in the second pressure tank 5. Consequently, the pressure p1 in the first pressure tank 3 experiences a faster increase than the pressure p2 in the second pressure tank 5.

[0107] The pressure p1 in the first pressure tank 3 stops increasing at the first estimated time t1 because it reaches the first threshold pressure th1. At this first threshold pressure, the first pressure relief valve rv1 begins to release fuel gas from the first pressure tank 3 into the atmosphere. Similarly, the pressure p2 in the second pressure tank 5 stops increasing at the second estimated time t2 because it reaches the second threshold pressure th2. At this second threshold pressure, the second pressure relief valve rv2 begins to release fuel gas from the second pressure tank 5 into the atmosphere.

[0108] In other words, in Figure 3 In the example described, each of the first time estimate t1 and the second time estimate t2 is within the dwell time period Sp.

[0109] According to some implementations, the control device 21 is configured to: if the first time estimate t1 is within the dwell period Sp, calculate the duration of the time period tp1 between the first time estimate t1 and the end of the dwell period Sp 82, and estimate the amount of fuel gas discharged through the first pressure relief valve rv1 during the dwell period Sp based on the stored data, model and the duration of the time period tp1.

[0110] Similarly, according to some embodiments, control device 21 may be configured to: if the second time estimate t2 is within the dwell period Sp, calculate the duration of the time period tp2 between the second time estimate t2 and the end of the dwell period Sp 82, and estimate the amount of fuel gas discharged via the second pressure relief valve rv2 during the dwell period Sp based on the stored data, model and the duration of the time period tp2.

[0111] Because of these features, control device 21 can estimate the amount of fuel gas discharged via one or both of the first relief valve rv1 and the second relief valve rv2 during the standby period Sp in a simple and efficient manner. The estimated amount of fuel gas discharged via one or both of the first relief valve rv1 and the second relief valve rv2 can be given in weight units, such as kilograms.

[0112] According to some implementations, control device 21 may be configured to input temperature data estimates into a model, wherein the temperature data estimates are representative estimated ambient temperatures during the stationary period. Control device 21 may be configured to receive temperature data estimates from an onboard system (such as from the control system 21' of vehicle 2), or may be configured to receive temperature data estimates from devices or systems external to vehicle 2.

[0113] Furthermore, according to some embodiments, control device 21 can be configured to input a fuel gas composition estimate into the model, wherein the fuel gas composition estimate represents the estimated composition of the fuel gas in the first pressure tank 3 at ph1 during the engine shutdown phase of vehicle 2. Similarly, control device 21 can be configured to input a second fuel gas composition estimate into the model, wherein the second fuel gas composition estimate represents the estimated composition of the fuel gas in the second pressure tank 5 at ph1 during the engine shutdown phase of vehicle 2.

[0114] Control device 21 may be configured to receive fuel gas composition estimates from an on-board system (such as control system 21' of vehicle 2), or may be configured to obtain fuel gas composition estimates from devices or systems outside vehicle 2. Alternatively or otherwise, control device 21 may be configured to obtain fuel gas composition estimates from an input unit that allows the user to input fuel gas composition estimates. The estimated value is composed of such input units, which may include, for example, a fleet management portal, a touchscreen located in the driver environment 40 of vehicle 2, a smartphone, etc.

[0115] The models for the state of the fuel gas in the first pressure tank 3 and the models for the state of the fuel gas in the second pressure tank 5 can be mathematical models for the respective states of the fuel gas in the pressure tanks 3 and 5. Such mathematical models for the states of the fuel gas in the respective pressure tanks 3 and 5 can represent physical models for the respective states of the fuel gas in the pressure tanks 3 and 5, such as simplified physical models. Each model can be based on the inputs described above, as well as the respective dimensions of the first pressure tank 3 and the second pressure tank 5, the estimated weights of the first pressure tank 3 and the second pressure tank 5, the estimated weights of the fuel gases in the first pressure tank 3 and the second pressure tank 5, the estimated heat transfer rates from the surrounding environment into the first pressure tank 3 and the second pressure tank 5, etc.

[0116] Furthermore, the models for the fuel gas state in the first pressure tank 3 and the second pressure tank 5 can respectively utilize the current volume estimates of the fuel gas in the first pressure tank 3 and the second pressure tank 5. The current volume estimates of the fuel gas in pressure tanks 3 and 5 can be calculated using the dimensions of pressure tanks 3 and 5 and the current fuel level in pressure tanks 3 and 5.

[0117] Each model may include equations based on the fact that the risk of fuel gas emission from fuel gas system 1 of vehicle 2 is proportional to the rate of heat transfer from the surrounding environment into the first pressure tank 3 and the second pressure tank 5, respectively. Similarly, each model may include equations based on the fact that the emission rate of fuel gas from fuel gas system 1 of vehicle 2 is proportional to the rate of heat transfer from the surrounding environment into the first pressure tank 3 and the second pressure tank 5, respectively. The emission rate of fuel gas from fuel gas system 1 of vehicle 2 may be given in units indicating weight / time, such as, for example, grams per second, grams per minute, etc.

[0118] According to some implementations, control device 21 is configured to measure the pressure p1 in the first pressure tank 3 during the start-up phase ph2 of vehicle 2, and to determine the accuracy of the estimate of whether the first pressure relief valve rv1 has started discharging during the parking period Sp based on the measured pressure p1. Control device 21 may be configured to measure the pressure p1 in the first pressure tank 3 by controlling the first valve v1 to be open before controlling the second valve v2 to be open and by inputting data from pressure sensor 15 after controlling the first valve v1 to be open.

[0119] As a first example, if it is estimated that the first pressure relief valve rv1 has started venting during the dwell period Sp, i.e., if the first time estimate t1 is within the dwell period Sp, but the measured pressure p1 in the first pressure tank 3 is significantly lower than the first threshold pressure th1, then it can be concluded that the estimate is inaccurate. As a second example, if it is estimated that the first pressure relief valve rv1 has not started venting during the dwell period Sp, and if the first time estimate t1 is a certain time distance from the end of the dwell period Sp 82, but the measured pressure p1 in the first pressure tank 3 is close to or at the first threshold pressure th1, then it can be concluded that the estimate is inaccurate.

[0120] According to some implementations, the control device 21 is configured to update at least one parameter of the model for the state of fuel gas in the first pressure tank 3 if the determined accuracy is lower than a threshold accuracy. The at least one parameter of the model may be, for example, a gain factor, variables, etc., of the model for the state of fuel gas in the first pressure tank 3.

[0121] The control device 21 may also be configured to generate a first type of error code if the measured pressure p1 in the first pressure tank 3 is outside the predetermined pressure range r1 and the first time estimate t1 is within the dwell period Sp. The control device 21 may also be configured to generate a second type of error code if the measured pressure p1 in the first pressure tank 3 is within the predetermined pressure range r1 and the first time estimate t1 is not within the dwell period Sp, wherein the second type of error code is separate from and distinguishable from the first type of error code.

[0122] exist Figure 3 The text indicates a predetermined pressure range r1 for the first pressure tank 3. This predetermined pressure range r1 for the first pressure tank 3 is set to be close to a first threshold pressure th1. The fact that the measured pressure p1 in the first pressure tank 3 is outside the predetermined pressure range r1 and the first time estimate t1 is within the dwell time Sp indicates that the estimate is incorrect or that the first pressure relief valve rv1 is open at too low a pressure. The fact that the measured pressure p1 in the first pressure tank 3 is within the predetermined pressure range r1 and the first time estimate t1 is not within the dwell time Sp can also indicate that the estimate is incorrect.

[0123] exist Figure 3The text also indicates a predetermined pressure range r2 for the second pressure tank 5. This predetermined pressure range r2 for the second pressure tank 5 is set to be close to a second threshold pressure th2. The control device 21 can be configured in the same manner as the first pressure tank 3 to measure the pressure p2 in the second pressure tank 5 during the vehicle 2 start-up phase ph2, and to determine the accuracy of the estimate of whether the second pressure relief valve rv2 has started discharging during the parking period Sp based on the measured pressure p2. The control device 21 can be configured to measure the pressure p2 in the second pressure tank 5 by controlling the second valve v2 to open before controlling the first valve v1 to open and by inputting data from the pressure sensor 15 after controlling the second valve v2 to open.

[0124] According to some implementations, control device 21 is configured to update at least one parameter of the model for the state of fuel gas in the second pressure tank 5 if the determined accuracy is lower than a threshold accuracy. The at least one parameter of the model may be, for example, a gain factor, variables, etc., of the model for the state of fuel gas in the second pressure tank 5.

[0125] The control device 21 can also be configured to generate a first type of error code and a second type of error code in the same manner as the first pressure tank 3, based on the measured pressure p2 in the second pressure tank 5 and the predetermined pressure range r2 of the second pressure tank 5.

[0126] According to some implementations, control device 21 is configured to: if the first time estimate t1 is before the second time estimate t2, then control the first valve v1 to the open state before controlling the second valve v2 to the open state; and if the first time estimate t1 is after the second time estimate t2, then control the second valve v2 to the open state before controlling the first valve v1 to the open state. In this way, the pressures p1 and p2 of the pressure tank most likely to discharge fuel gas from its pressure relief valves rv1 and rv2 during the dwell period Sp are measured. In this way, improved conditions are provided for generating error codes and / or determining the accuracy of estimates of whether pressure relief valves rv1 and rv2 have begun discharging during the dwell period Sp.

[0127] According to some embodiments, control device 21 may be configured to record the number of times pressure monitoring of the first pressure tank 3 and the second pressure tank 5 has been performed. According to such embodiments, control device 21 may be configured to open one of the first pressure tank 3 and the second pressure tank 5 based on the fact that valves v1 and v2 of pressure tanks 3 and 5 have not been opened multiple times before the other valve v1 and v2.

[0128] According to the embodiments described herein, control device 21 may be configured to output one or more of the following to an output unit and / or external device or system arranged in the driver environment 40 of vehicle 2: an estimate of whether the first pressure relief valve rv1 has started discharging during the parking period Sp; an estimate of whether the second pressure relief valve rv2 has started discharging during the parking period Sp; an estimate of the amount of fuel gas discharged via the first pressure relief valve rv1 during the parking period Sp; and an estimate of the amount of fuel gas discharged via the second pressure relief valve rv2 during the parking period Sp. Such external device or system may, for example, be part of a fleet management portal.

[0129] Output units arranged in the driver environment 40 of vehicle 2 may include, for example, displays, speakers, etc. Examples of external devices and systems are smartphones and external databases, such as external databases storing data from the fleet management portal. By outputting such data to output units and / or external devices or systems arranged in the driver environment 40 of vehicle 2, control device 21 allows the owner and operator of vehicle 2 to take necessary measures to prevent fuel gases from the fuel gas system 1 from being emitted into the atmosphere in the future. As a further result, conditions are provided that allow owners and operators to enhance their environmental responsibility and reduce the operating costs of their vehicle 2.

[0130] As indicated above, the fuel gas system 1 of vehicle 2 may include a number of pressure tanks 3, 5 in addition to two, such as one or more pressure tanks. In embodiments where the fuel gas system 1 of vehicle 2 includes more than two pressure tanks, control device 21 may be configured to estimate, in the same manner as described above for the first pressure tank 3 and the second pressure tank 5, whether the pressure relief valves of one or more of the other pressure tanks of fuel gas system 1 have begun to vent during the rest period Sp. Similarly, control device 21 may be configured to estimate, in the same manner as the first pressure tank 3 and the second pressure tank 5 described above, the amount of fuel gas vented through the pressure relief valves of one or more such other pressure tanks during the rest period Sp.

[0131] Figure 4 A method 100 for estimating the generation of fuel gas emissions from a vehicle's fuel gas system is illustrated schematically. The vehicle may be as shown in the reference... Figures 1 to 3 Vehicle 2 is explained. Therefore, unless otherwise indicated below, refer also to Figures 1 to 4 .

[0132] Method 100 is a method for estimating the occurrence of fuel gas emissions from a fuel gas system 1 of a vehicle 2, wherein the fuel gas system 1 is configured to supply fuel gas to a power source 30 of the vehicle 2, and wherein the fuel gas system 1 includes a first pressure tank 3 and a first pressure relief valve rv1, the first pressure relief valve being configured to begin discharging fuel gas from the first pressure tank 3 when the pressure p1 in the first pressure tank 3 reaches or exceeds a first threshold pressure th1. Method 100 includes the following steps: - During the engine shutdown phase ph1 of vehicle 2, storage 110 stores data representing the current time and date, the current pressure p1 in the first pressure tank 3, and the current fuel level in the first pressure tank 3; - Based on the stored data and a model of the fuel gas state in the first pressure tank 3, obtain the estimated first time t1 at which the first pressure relief valve rv1 begins to discharge; and After the parking period Sp begins at the start of the engine shutdown phase ph1 of vehicle 2: - Estimate whether the first pressure relief valve rv1 has started discharging during the parking period Sp by checking whether the first time estimate t1 is within the parking period Sp.

[0133] According to some implementation schemes, the step of obtaining the first time estimate t1 of 120 is performed during the start-up phase ph2 of vehicle 2.

[0134] Furthermore, the step of estimating whether the first pressure relief valve rv1 of vehicle 130 has started to discharge is performed during the start-up phase ph2 of vehicle 2.

[0135] like Figure 4 As indicated, method 100 may include the following steps: Input the temperature data estimate into the model, where the temperature data estimate is a representative estimated ambient temperature during the stopover period Sp.

[0136] In addition, such as Figure 4 As indicated, method 100 may include the following steps: Input the fuel gas composition estimate into the model (122), where the fuel gas composition estimate represents the estimated composition of the fuel gas in the first pressure tank 3 (ph1) during the engine shutdown phase of vehicle 2.

[0137] According to some embodiments, the fuel gas system 1 includes a second pressure tank 5 and a second pressure relief valve rv2, the second pressure relief valve being configured to begin discharging fuel gas from the second pressure tank 5 when the pressure p2 in the second pressure tank 5 reaches or exceeds a second threshold pressure th2, wherein the method 100 includes the following steps: - During the engine shutdown phase ph1 of vehicle 2, store data representing the current pressure p2 in the second pressure tank 5 and the current fuel level in the second pressure tank 5; - Based on the stored data and a model of the fuel gas state in the second pressure tank 5, obtain the second estimated time t2 for the second pressure relief valve rv2 to begin discharging; and After the stationary period Sp begins during the engine shutdown phase ph1 of vehicle 2: - Estimate whether the second pressure relief valve rv2 has started discharging during the dwell period Sp by checking whether the second time estimate t2 is within the dwell period Sp.

[0138] like Figure 4 As indicated, method 100 may include the following steps: - Input the fuel gas composition estimate into 122' into the model for the fuel gas state in the second pressure tank 5, where the fuel gas composition estimate represents the estimated composition of the fuel gas in the second pressure tank 5 during the engine shutdown phase ph1 of the vehicle 2.

[0139] According to some implementation schemes, method 100 includes the following steps: if the first-time estimate t1 falls within the dwell period Sp, then: - Calculate the duration of the time interval tp1 between the first time estimate t1 and the end of the dwell period Sp; and - Estimate the amount of fuel gas emitted by 142 via the first pressure relief valve rv1 during the standby period Sp based on the stored data, model and duration of time period tp1.

[0140] Furthermore, according to some implementation schemes, method 100 includes the following steps: if the second time estimate t2 falls within the dwell period Sp, then: - Calculate the duration of the time interval tp2 between the second time estimate t2 and the end of the dwell period Sp; and -Based on the stored data, the model of the fuel gas state in the second pressure tank 5, and the duration of time period tp2, estimate the amount of fuel gas discharged via the second pressure relief valve rv2 during the standby period Sp.

[0141] like Figure 4 As indicated, method 100 may include performing the following steps during the start-up phase ph2 of vehicle 2: -Measure the pressure p1 in the first pressure tank 3 of 150; and - The accuracy of the estimate of whether the first pressure relief valve rv1 of 152 has started to discharge during the standby period Sp is determined based on the measured pressure p1.

[0142] Optionally, method 100 includes the following steps: - If the determined accuracy is below the threshold accuracy, then update at least one parameter of the model for the state of fuel gas in the first pressure tank 3.

[0143] According to some implementation schemes, method 100 includes performing the following steps during the start-up phase ph2 of vehicle 2: -Measure the pressure p1 in the first pressure tank 3 of 150; and - If the measured pressure p1 is outside the predetermined pressure range r1 and the first time estimate t1 is within the dwell period Sp, then error code 156 of type 1 is generated.

[0144] Furthermore, according to some implementation schemes, method 100 includes performing the following steps during the start-up phase ph2 of vehicle 2: -Measure the pressure p1 in the first pressure tank 3 of 150; and - If the measured pressure p1 is within the predetermined pressure range r1 and the first time estimate t1 is not within the dwell period Sp, then error code 157 (Type 2) is generated.

[0145] In addition, such as Figure 4 As indicated, method 100 may include performing the following steps during the start-up phase ph2 of vehicle 2: - Measure the pressure p2 in the second pressure tank 5 (150'); and - The accuracy of the estimate of whether the second pressure relief valve rv2 has started to discharge during the pause period Sp is determined based on the measured pressure p2.

[0146] Optionally, method 100 includes the following steps: - If the determined accuracy is below the threshold accuracy, then update at least one parameter of the model for the state of fuel gas in the second pressure tank 5.

[0147] According to some implementation schemes, method 100 includes performing the following steps during the start-up phase ph2 of vehicle 2: - Measure the pressure p2 in the second pressure tank 5 (150'); and - If the measured pressure p2 is outside the predetermined pressure range r2 and the second time estimate t2 is within the dwell period Sp, then error code 156' of type 1 is generated.

[0148] Furthermore, according to some implementation schemes, method 100 includes performing the following steps during the start-up phase ph2 of vehicle 2: - Measure the pressure p2 in the second pressure tank 5 (150'); and - If the measured pressure p2 is within the predetermined pressure range r2 and the second time estimate t2 is not within the dwell period Sp, then error code 157' type 2 is generated.

[0149] Optionally, the fuel gas system 1 includes: a supply pipe 7 configured to supply fuel gas from a first pressure tank 3 to a power source 30 of the vehicle 2; a pressure sensor 15 configured to measure pressure in the supply pipe 7; and a first valve v1 controllable between an open and closed state to open and close the fluid connection between the first pressure tank 3 and the supply pipe 7, wherein method 100 includes the following steps: -During the start-up phase ph2 of vehicle 2, control the first valve v1 to the open state 132. The step of measuring the pressure p1 in the first pressure tank 3 (150) includes the following steps: - Input 151, data from pressure sensor 15.

[0150] Optionally, the fuel gas system 1 includes: a supply pipe 7 configured to supply fuel gas from a second pressure tank 5 to a power source 30 of the vehicle 2; a pressure sensor 15 configured to measure pressure in the supply pipe 7; and a second valve v2 controllable between an open and closed state to open and close the fluid connection between the second pressure tank 5 and the supply pipe 7, wherein method 100 includes the following steps: -During the start-up phase ph2 of vehicle 2, control the second valve v2 to the open state. The step of measuring the pressure p2 in the second pressure tank 5 (150) includes the following steps: - Input 151' Data from pressure sensor 15.

[0151] According to some embodiments, the fuel gas system 1 includes a pressure sensor 15 configured to provide data representing the current pressure p1 in the first pressure tank 3, and wherein the step of storing 110 data during the engine shutdown phase ph1 of the vehicle 2 includes the following steps: - Store data from pressure sensor 15.

[0152] According to some embodiments, the fuel gas system 1 includes a pressure sensor 15 configured to provide data representing the current pressure p2 in the second pressure tank 5, and wherein the step of storing 110 data during the engine shutdown phase ph1 of the vehicle 2 includes the following steps: - Store data from pressure sensor 15.

[0153] Optionally, the fuel gas system 1 includes a first level sensor L1 configured to provide data representing the current fuel level in the first pressure tank 3, and wherein the step of storing the data during the engine shutdown phase ph1 of the vehicle 2 includes the following steps: -Store 113 data from the first liquid level sensor L1.

[0154] Similarly, optionally, the fuel gas system 1 includes a second level sensor L2, which is configured to provide data representing the current fuel level in the second pressure tank 5, and wherein the step of storing the data during the engine shutdown phase ph1 of the vehicle 2 includes the following steps: - Store data from the second liquid level sensor L2 (113').

[0155] According to some embodiments, the fuel gas system 1 includes: a supply conduit 7 configured to supply fuel gas from each of a first pressure tank 3 and a second pressure tank 5 to a power source 30 of the vehicle 2; a first valve v1 controllable between an open and closed state to open and close a fluid connection between the first pressure tank 3 and the supply conduit 7; and a second valve v2 controllable between an open and closed state to open and close a fluid connection between the second pressure tank 5 and the supply conduit 7, wherein method 100 includes the following steps: - If the first time estimate t1 is before the second time estimate t2, then the first valve v1 is controlled to the open state by 160 before the second valve v2 is controlled to the open state; and -If the first time estimate t1 is after the second time estimate t2, then the second valve v2 is controlled to the open state before the first valve v1 is controlled to the open state.

[0156] It should be understood that all the various implementations described for method 100 can be combined with the control device 21 as described herein. That is, the control device 21 can be configured to perform any of the method steps 110, 110', 111, 111', 113, 113', 120, 120', 121, 122, 122', 130, 130', 132, 132', 140, 140', 142, 142', 150, 150', 151, 151', 152, 152', 153, 153', 156, 156', 157, 157', 160, and 161.

[0157] Figure 5A computer-readable medium 200 is illustrated, which, when executed by a computer, causes the computer to perform method 100 according to some embodiments of the present disclosure. According to some embodiments, the computer-readable medium 200 includes a computer program that includes instructions that, when executed by a computer, cause the computer to perform method 100 according to some embodiments. The computer may be included in a control device 21.

[0158] Those skilled in the art will understand that the method 100 for estimating the occurrence of fuel gas emissions from the fuel gas system 1 of vehicle 2 can be implemented by programming instructions. These programming instructions typically constitute a computer program that, when executed in a control unit 21, ensures that the control unit 21 performs the required controls, such as the method steps 110, 110', 111, 111', 113, 113', 120, 120', 121, 122, 122', 130, 130', 132, 132', 140, 140', 142, 142', 150, 150', 151, 151', 152, 152', 153, 153', 156, 156', 157, 157', 160, and 161. The computer program is typically part of a computer program product, which includes a suitable digital storage medium on which the computer program is stored, such as... Figure 5 The illustrated computer-readable medium 200. In other words, a computer program product can be a computer-readable medium 200, and a computer program can be stored in a computer-readable medium 200.

[0159] Control device 21 may include a computer, which may take the form of substantially any suitable type of hardware or hardware / firmware device implemented using processing circuitry, such as, but not limited to, a processor, central processing unit (CPU), controller, arithmetic logic unit (ALU), digital signal processor, application-specific integrated circuit (ASIC), circuitry for digital signal processing (DSP), microcomputer, field-programmable gate array (FPGA), system-on-a-chip (SoC), programmable logic unit, microprocessor, application-specific integrated circuit, or any other device capable of electronically performing operations in a defined manner, or other processing logic capable of interpreting and executing instructions. As used herein, the term "computer" may refer to a system of processing circuitry comprising multiple processing circuitry, such as any, some, or all of the processing circuitry mentioned above.

[0160] The control device 21 may also include a memory unit, to which a computer can be connected. The memory unit provides the computer with stored program code and / or stored data, such as data that the computer might need to enable it to perform calculations. The computer may also be adapted to store partial or final results of calculations in the memory unit. The memory unit may include physical devices for temporarily or permanently storing data or programs (i.e., sequences of instructions). According to some embodiments, the memory unit may include integrated circuits comprising silicon-based transistors. In various embodiments, the memory unit may include, for example, a memory card, flash memory, USB storage, a hard disk, or other similar volatile or non-volatile memory units for storing data, such as, for example, ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM), etc.

[0161] Control device 21 is connected to components of vehicle 2 for receiving and / or transmitting input and output signals. These input and output signals may include waveforms, pulses, or other properties that can be detected as information by the input signal receiving device and converted into signals that can be processed by control device 21. These signals can then be supplied to a computer. One or more output signal transmitting devices may be arranged to convert calculation results from the computer into output signals for transmission to other parts of the vehicle control system and / or the components to which the signals are directed. Each connection to the corresponding components of vehicle 2 for receiving and transmitting input and output signals may take one or more forms, such as cables, data buses (e.g., CAN (Controller Area Network) bus, MOST (Media Directed Transmission) bus, or some other bus configuration), or wireless connections.

[0162] In the illustrated embodiments, vehicle 2 includes control device 21, but it may alternatively be implemented wholly or partially in two or more control devices, two or more control units, or two or more control units. Furthermore, according to some embodiments, at least a portion of control device 21, as mentioned herein, may be located outside vehicle 2, i.e., it may be included in a device or system separate from vehicle 2.

[0163] Control systems in modern vehicles typically include a communication bus system, which comprises one or more communication buses for connecting multiple electronic control units (ECUs) or controllers to various components on the vehicle. Such control systems may include a large number of control units, and it should be noted that specific functions may be shared among two or more of them. Therefore, as those skilled in the art will certainly understand, vehicles and engines of the type discussed herein are typically equipped with more... Figure 2 The control device depicted in the text has significantly more control devices.

[0164] Computer-readable medium 200 may be provided, for example, in the form of a data carrier carrying computer program code for performing at least some of the method steps 110, 110', 111, 111', 113, 113', 120, 120', 121, 122, 122', 130, 130', 132, 132', 140, 140', 142, 142', 150, 150', 151, 151', 152, 152', 153, 153', 156, 156', 157, 157', 160, and 161, according to some embodiments of method 100, when loaded into one or more computers of control device 21. The data carrier may be, for example, a CD-ROM (e.g., Figure 5 (as shown) or ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), flash memory, EEPROM (Electrically Erasable PROM), hard disk, memory stick, optical storage device, magnetic storage device, or any other suitable medium, such as a disk or magnetic tape, that can hold machine-readable data in a non-transient manner.

[0165] Therefore, in some embodiments, the computer-readable medium 200 may be a non-transitory computer-readable medium, such as a tangible electronic, magnetic, optical, infrared, electromagnetic, and / or semiconductor system, apparatus, and / or device. The computer-readable medium 200 may also be provided as computer program code on a server and may be remotely downloaded to the control device 21, for example, via an Internet or intranet connection or through other wired or wireless communication systems.

[0166] It should be understood that the foregoing description is illustrative of various exemplary embodiments, and the invention is defined solely by the appended independent claims. Those skilled in the art will recognize that modifications can be made to the exemplary embodiments without departing from the scope of the invention as defined by the appended independent claims, and different features of the exemplary embodiments can be combined to produce embodiments other than those described herein.

[0167] As used herein, the terms “comprising” or “comprises” are open-ended and include one or more of the stated features, elements, steps, components, or functions, but do not exclude the presence or addition of one or more other features, elements, steps, components, functions, or groups thereof.

Claims

1. A method (100) for estimating the occurrence of fuel gas emissions from a fuel gas system (1) of a vehicle (2), wherein the fuel gas system (1) is configured to supply fuel gas to a power source (30) of the vehicle (2), and wherein the fuel gas system (1) includes a first pressure tank (3) and a first pressure relief valve (rv1), the first pressure relief valve being configured to begin discharging fuel gas from the first pressure tank (3) when the pressure (p1) in the first pressure tank (3) reaches a first threshold pressure (th1) above the threshold pressure, wherein the method (100) includes the following steps: - During the engine shutdown phase (ph1) of the vehicle (2), the storage (110) stores data representing the current time and date, the current pressure (p1) in the first pressure tank (3), and the current fuel level in the first pressure tank (3); - Based on the stored data and a model of the fuel gas state in the first pressure tank (3), obtain (120) an estimate of the first time (t1) at which the first pressure relief valve (rv1) begins to discharge; and After the parking period (Sp) that begins at the start of the engine shutdown phase (ph1) of the vehicle (2): - Estimate (130) whether the first pressure relief valve (rv1) has started discharging during the pause period (Sp) by checking whether the first time estimate (t1) is within the pause period (Sp).

2. The method (100) according to claim 1, wherein the step of obtaining (120) the first time estimate (t1) is performed during the start-up phase (ph2) of the vehicle (2).

3. The method (100) according to claim 1 or 2, wherein the step of estimating (130) whether the first pressure relief valve (rv1) has started to discharge is performed during the start-up phase (ph2) of the vehicle (2).

4. The method (100) according to any one of the preceding claims, wherein the method (100) comprises the following steps: - Input the temperature data estimate (121) into the model, wherein the temperature data estimate is a representative estimated ambient temperature during the dwell time (Sp).

5. The method (100) according to any one of the preceding claims, wherein the method (100) comprises the following steps: - Input (122) the estimated value of fuel gas composition into the model, wherein the estimated value of fuel gas composition represents the estimated composition of the fuel gas in the first pressure tank (3) during the shutdown phase (ph1) of the vehicle (2).

6. The method (100) according to any one of the preceding claims, wherein the method (100) comprises the steps of: If the first time estimate (t1) falls within the dwell time period (Sp), then: - Calculate (140) the duration of the time period (tp1) between the first time estimate (t1) and the end (82) of the pause period (Sp); as well as - Estimate (142) the amount of fuel gas discharged via the first pressure relief valve (rv1) during the standby period (Sp) based on the stored data, the model and the duration of the time period (tp1).

7. The method (100) according to any of the preceding claims, wherein the method (100) comprises the steps of: During the start-up phase (ph2) of the vehicle (2), - Measure (150) the pressure (p1) in the first pressure vessel (3); and - Determine (152) the accuracy of the estimate of whether the first pressure relief valve (rv1) has started to discharge during the pause period (Sp) based on the measured pressure (p1).

8. The method (100) according to claim 7, wherein the method (100) comprises the steps of: - If the determined accuracy is below the threshold accuracy, then update (153). At least one parameter of the model.

9. The method (100) according to any one of the preceding claims, wherein the method (100) comprises the steps of: During the start-up phase (ph2) of the vehicle (2): - Measure (150) the pressure (p1) in the first pressure vessel (3); and - If the measured pressure (p1) is in If the pressure range (r1) is outside the predetermined pressure range and the first time estimate (t1) is within the dwell period (Sp), then an error code of type (156) is generated.

10. The method (100) according to any one of the preceding claims, wherein the method (100) comprises the steps of: During the start-up phase (ph2) of the vehicle (2): - Measure (150) the pressure (p1) in the first pressure vessel (3); and - If the measured pressure (p1) is within the predetermined pressure range (r1) and the first time estimate (t1) is not within the dwell period (Sp), then a second type of error code (157) is generated.

11. The method (100) according to any one of claims 7 to 10, wherein the fuel gas system (1) comprises: - Supply pipe (7), the supply pipe being configured to supply fuel gas from the first pressure tank (3) to the power source (30) of the vehicle (2); - Pressure sensor (15), the pressure sensor being configured to measure the pressure in the supply pipe (7); and - A first valve (v1), which is controllable between an open and closed state to open and close the fluid connection between the first pressure tank (3) and the supply pipe (7). And the method (100) described therein includes the following steps: - During the start-up phase (ph2) of the vehicle (2), the first valve (v1) is controlled (132) to the open state. And the step of measuring (150) the pressure (p1) in the first pressure vessel (3) includes the following steps: - Input (151) data from the pressure sensor (15).

12. The method (100) according to any one of the preceding claims, wherein the fuel gas system (1) comprises a pressure sensor (15) configured to provide data indicative of a current pressure (pi) in the first pressure tank (3), and wherein the step of storing (110) data during the off-phase (ph1) of the vehicle (2) comprises the step of: - Store (111) the data from the pressure sensor (15).

13. The method (100) according to any one of the preceding claims, wherein the fuel gas system (1) comprises a first liquid level sensor (LI) configured to provide data indicative of a current fuel level in the first pressure tank (3), and wherein the step of storing (110) data during the off-phase (phl) of the vehicle (2) comprises the step of: - Store (113) the data from the first liquid level sensor (L1).

14. The method (100) according to any one of the preceding claims, wherein the fuel gas system (1) includes a second pressure tank (5) and a second pressure relief valve (rv2), the second pressure relief valve being configured to begin discharging fuel gas from the second pressure tank (5) when the pressure (p2) in the second pressure tank (5) reaches or exceeds a second threshold pressure (th2). The method (100) includes the following steps: - During the engine shutdown phase (ph1) of the vehicle (2), the storage (110') represents data on the current pressure (p2) in the second pressure tank (5) and the current fuel level in the second pressure tank (5); - Based on the stored data and a model of the fuel gas state in the second pressure tank (5), obtain (120') a second time estimate (t2) for the start of discharge from the second pressure relief valve (rv2); and After the shutdown phase (ph1) of the vehicle (2) begins and the parking period (Sp) begins: - the second pressure relief valve (rv2) is estimated (130') by checking whether the second time estimate (t2) is within the parking period (Sp). Whether emissions have started during the said standby period (Sp).

15. The method (100) according to claim 14, wherein the fuel gas system (1) comprises: - Supply pipe (7), the supply pipe being configured to supply fuel gas from each of the first pressure tank (3) and the second pressure tank (5) to the power source (30) of the vehicle (2); - First valve (v1), which is controllable between an open state and a closed state to open and close the fluid connection between the first pressure tank (3) and the supply pipe (7); and - A second valve (v2), which is controllable between an open and closed state to open and close the fluid connection between the second pressure tank (5) and the supply pipe (7). The method (100) includes the following steps: - If the first time estimate (t1) is earlier than the second time estimate (t2), then the first valve (v1) is controlled (160) to the open state before the second valve (v2) is controlled to the open state; and - If the first time estimate (t1) is after the second time estimate (t2), then the second valve (v2) is controlled (161) to the open state before the first valve (v1) is controlled to the open state.

16. A computer program comprising instructions which, when executed by a computer, cause the computer to perform the method (100) according to any one of claims 1 to 15.

17. A computer-readable medium comprising instructions that, when executed by a computer, cause the computer to perform the method (100) according to any one of claims 1 to 15.

18. A control device (21) configured to estimate the occurrence of fuel gas emissions from a fuel gas system (1) of a vehicle (2), wherein the fuel gas system (1) is configured to supply fuel gas to a power source (30) of the vehicle (2), and wherein the fuel gas system (1) includes a first pressure tank (3) and a first pressure relief valve (rv1). The first pressure relief valve is configured to begin discharging fuel gas from the first pressure tank (3) when the pressure (p1) in the first pressure tank (3) reaches or exceeds a first threshold pressure (th1), wherein the control device (21) is configured to: - During the engine shutdown phase (ph1) of the vehicle (2), data representing the current time and date, the current pressure (p1) in the first pressure tank (3), and the current fuel level in the first pressure tank (3) are stored; - Based on the stored data and a model of the fuel gas state in the first pressure tank (3), obtain an estimate of the first time (t1) at which the first pressure relief valve (rv1) begins to discharge; and After the parking period (Sp) that begins at the start of the engine shutdown phase (ph1) of the vehicle (2): - Estimate whether the first pressure relief valve (rv1) has started discharging during the pause period (Sp) by checking whether the first time estimate (t1) is within the pause period (Sp).

19. A vehicle (2) comprising a power source (30) and a fuel gas system (1) configured to supply fuel gas to the power source (30), wherein the fuel gas system (1) comprises a first pressure tank (3) and a first pressure relief valve (rv1) configured to begin discharging fuel gas from the first pressure tank (3) when the pressure (p1) in the first pressure tank (3) reaches a first threshold pressure (th1) above, and wherein the vehicle (2) comprises a control device (21) according to claim 18.

20. The vehicle (2) according to claim 19, wherein the first pressure tank (3) is a cryogenic storage tank, the cryogenic storage tank being configured to store the fuel gas at least partially in liquid form and at a temperature below ambient temperature.

21. The vehicle (2) according to claim 19 or 20, wherein the vehicle (2) is a heavy road vehicle (2), such as a truck or a bus.

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