Method for operating tank arrangement for storing gaseous fuel and tank arrangement for storing gaseous fuel

Abstract

The invention relates to a method for operating a tank arrangement (1) for storing gaseous fuel for a motor vehicle. The invention also relates to a tank arrangement (1) for storing gaseous fuel for a motor vehicle, comprising at least one tank container (TB1, TB2,..., TBn) and at least one valve device.

Description

Technical Field

[0001] The invention relates to a method for operating a tank arrangement for storing gaseous fuel and a tank arrangement for storing gaseous fuel. Background Art

[0002] Safety devices and / or valves can be installed in known pressure tanks. For this purpose, fuel cell systems are known that have tank arrangements or tanks for gaseous media. To stabilize the pressure tanks and prevent or at least mitigate the outflow of gas in the event of an increase in the temperature of the stored medium or a leak, the pressure tanks can be equipped with valves, for example. However, it would be desirable to gain better knowledge of the tank fill level and leaks in the tank arrangement in order to improve the operation of the motor vehicle and its fuel supply in an operational state.

[0003] In an H2 tank system which typically has a plurality of gas tanks each equipped with a respective tank valve, not all tanks have to be equipped with a respective pressure sensor.

[0004] DE 11 2006 003 013 B4 discloses a tank having a tap and a valve, wherein the valve is fixed in the tap. Summary of the Invention

[0005] The invention provides a method for operating a tank arrangement for storing gaseous fuel according to claim 1 and a tank arrangement for storing gaseous fuel according to claim 12 .

[0006] Preferred further developments are the subject matter of the dependent claims.

[0007] The invention is based on the idea of ​​specifying a method for operating a tank arrangement for storing gaseous fuel and a tank arrangement for storing gaseous fuel, wherein the location and detection of leaks in the tank arrangement can be improved.

[0008] According to the present invention, the location and detection of leaks in the high-pressure region and / or the medium-pressure region can be advantageously improved, wherein one or more tank containers can belong to the high-pressure region. For this purpose, one or more tank containers can each include a temperature sensor.

[0009] According to the invention, in a method for operating a tank arrangement, gas discharge from a medium-pressure region of a gas pipeline system is stopped;

[0010] detecting a first pressure in the high-pressure region and a first temperature in the high-pressure region by means of a first pressure sensor, and detecting a second pressure in the medium-pressure region and a second temperature in the medium-pressure region by means of a second pressure sensor;

[0011] Determining an average temperature in the medium-pressure region and an average temperature in the high-pressure region based on the determined first temperature and second temperature;

[0012] determining a first reference density in the high-pressure region as a function of the first pressure and the average temperature in the high-pressure region, and determining a second reference density in the medium-pressure region as a function of the second pressure and the average temperature in the medium-pressure region;

[0013] re-detecting the first pressure, the first temperature, the second pressure, and the second temperature in the high-pressure region and the medium-pressure region before re-taking gas from the medium-pressure region of the gas pipeline;

[0014] determining a current average value of the temperatures in the medium-pressure region and the high-pressure region from the re-detected first temperature and second temperature;

[0015] determining a current density in the high-pressure region and the medium-pressure region from a current average value of the temperature and the first pressure and the second pressure;

[0016] The current densities in the high-pressure and medium-pressure regions are compared with corresponding reference densities and deviations between the current densities and the reference densities are checked for leaks in the high-pressure and / or medium-pressure regions according to predetermined verification rules.

[0017] To this end, the tank arrangement comprises: at least one tank container having at least one valve device; a gas pipeline system, to which the at least one tank container is connected via a valve device; a first pressure sensor in the high-pressure area of ​​the gas pipeline system and a second pressure sensor in the medium-pressure area of ​​the gas pipeline system, wherein the respective tank container is connected to the high-pressure area of ​​the gas pipeline system and the high-pressure area is connected to the medium-pressure area via a regulating valve; and a control device, which is connected to the pressure sensor and the at least one valve device.

[0018] The method according to the present invention advantageously allows leaks in a tank system to be detected while the motor vehicle and / or the consumer system are at a standstill. Advantageously, a gaseous fuel consumer can be shut down, in other words, valves to the consumer and / or valves on the tank container and toward the gas line system can be closed. For example, the consumer can be shut down in terms of its operation (in the closed state) and / or valves on the anode side of the fuel cell can be closed, for example, when the consumer is a fuel cell (in this case, a so-called ASV, or anode shutoff valve, can be closed).

[0019] Advantageously, pressure sensors in the high-pressure region and the medium-pressure region as well as temperature sensors in the tank container can be evaluated.

[0020] The term “corresponding tank container” within the meaning of the present invention can also be replaced by “a tank container” or “all tank containers”, and the same applies to the tank filling level.

[0021] The average temperature can be determined over a plurality of tank containers and / or at a plurality of selected points in the pipeline system, ie over time and / or over space.

[0022] Thus, sensors (for pressure and temperature) may be present in the tank container and in the high-pressure and / or medium-pressure regions, wherein temperature values ​​can be retrieved. Alternatively or additionally, the ambient temperature can also be determined, for example, via a sensor, a model, or data exchange with a data platform, wherein such temperature determination also applies to all other temperatures in or around the tank system. For example, when the system is equilibrated with the ambient temperature, the ambient temperature can be used to determine the density before reopening the valve.

[0023] The reference density can be the expected density at the respective operating point (eg also at standstill), also taking into account the prevailing boundary conditions such as the ambient temperature or the fill level or others.

[0024] According to a preferred embodiment of the method, before shutting down the gas consumer, a pressure reduction takes place in the high-pressure region after closing the valve arrangement between the gas line system and the at least one tank container.

[0025] Advantageously, a targeted local decompression (pressure reduction) can be performed in the high-pressure area before or during a shutdown. This can be achieved, for example, by idling the consumer after closing the valve system on the tank container. Alternatively or additionally, the temperature profile at the tank container and / or in the pipeline system (high-pressure area and / or medium-pressure area) can be determined during a predetermined downtime. The control device can be regularly activated at defined time intervals, and the determined temperatures can be measured and / or stored throughout the day and / or night. Additionally or alternatively, temperature information can be acquired via a data exchange platform, so-called connected services, taking into account the location of the motor vehicle. In this way, the temperature in the high-pressure area and / or medium-pressure area can be determined using a model or sensors, and the average temperature in the respective area can be determined.

[0026] According to a preferred embodiment of the method, the predetermined calibration rule relates to the density increase in the high-pressure region and infers a leak in the valve arrangement therefrom.

[0027] According to a preferred embodiment of the method, the preselected verification rule relates to a density reduction in the high-pressure region and the inference of the presence of a leak in the high-pressure region, wherein an additional density increase in the medium-pressure region indicates the presence of an internal leak in the control valve between the high-pressure region and the medium-pressure region.

[0028] According to a preferred embodiment of the method, the predetermined calibration rule relates to a density increase in the medium-pressure region and infers a refill or a leak at the control valve between the high-pressure region and the medium-pressure region.

[0029] According to a preferred embodiment of the present invention, the predetermined verification rule relates to a density reduction in the medium-pressure region and infers a leak in the medium-pressure region, wherein, when a density change additionally occurs at the injection point of the consumer, a fault at the consumer is inferred, and when there is no density change at the injection point of the consumer, a leak in the medium-pressure region relative to the surroundings is inferred.

[0030] According to a preferred embodiment of the present invention, the pressure and temperature in the high-pressure area and in the medium-pressure area are determined by means of pressure sensors and by temperature sensors in the high-pressure area and / or in the medium-pressure area and / or by temperature models for the high-pressure area and for the medium-pressure area over a plurality of predetermined time points and a plurality of predetermined time intervals, and / or information about the ambient temperature of the data platform is determined.

[0031] According to a preferred embodiment of the present invention, it is determined whether the overpressure valve connecting the medium-pressure area to the surrounding environment has been opened during a static phase between stopping gas extraction and re-extracting gas, wherein a pressure change curve and a temperature change curve are determined in the medium-pressure area over a plurality of predetermined time points, and the temperature change curve thus determined is compared with a temperature value for triggering the overpressure valve and the pressure change curve thus determined is compared with a pressure value for triggering the overpressure valve, and the prevailing conditions for opening the overpressure valve are inferred therefrom.

[0032] According to a preferred embodiment of the present invention, the density normally expected in the medium-pressure region is determined by determining the lowest temperature in the medium-pressure region during a predetermined time period after stopping gas extraction and before re-examination of gas, and by determining the pressure when the regulating valve between the high-pressure region and the medium-pressure region is closed.

[0033] According to a preferred embodiment of the invention, an internal leak in the control valve between the high-pressure region and the medium-pressure region is detected if the density in the medium-pressure region increases compared to the normally expected density in the medium-pressure region.

[0034] According to a preferred embodiment of the method, the average temperature is determined with the aid of a temperature model.

[0035] The gas conduit may be used to supply gaseous fuel to the tank container and also to transfer gas from the tank container to an engine or a fuel cell of a motor vehicle.The valve arrangement may comprise a closable valve which may be opened and closed electrically.

[0036] The motor vehicle may be a fuel cell motor vehicle. The gaseous fuel may be a gaseous gas used to operate the fuel cell, such as hydrogen or another gas suitable for this purpose. Alternatively, the gaseous fuel may be a gas used for gas-powered motor vehicles, such as CNG or LPG, in which case it may also be a liquid gas.

[0037] A motor vehicle with a fuel cell system may contain tank containers filled with gaseous fuel, one or more of which may be under high pressure (up to a nominal value of 700 bar). During downtime in a motor vehicle with an H2 storage system, different pressures may develop in the individual tanks. This is due to different temperature changes in the individual tanks, for example, due to different tank designs or different ambient conditions at the tanks, which result in different heating or cooling. These differences or influences can be taken into account for the individual tanks.

[0038] The tank device can also be enhanced by combining the features and advantages mentioned above with the method, and vice versa.

[0039] According to the present invention, a tank device for storing gaseous fuel for motor vehicles comprises: at least one tank container having at least one valve device; a gas pipeline system, to which the at least one tank container is connected via a valve device; a first pressure sensor in the high-pressure area of ​​the gas pipeline system and a second pressure sensor in the medium-pressure area of ​​the gas pipeline system, wherein each tank container is connected to the high-pressure area of ​​the gas pipeline system and the high-pressure area is connected to the medium-pressure area via a regulating valve; a control device, which is connected to the pressure sensor and the at least one valve device and is configured to perform the method according to the present invention.

[0040] Advantageously, the density determination in the high-pressure region and the medium-pressure region can be performed at a time after the consumer has been shut down. For this purpose, pressure and temperature measurements can be performed in the high-pressure region. An average temperature can then be determined for the high-pressure region and / or the medium-pressure region based on existing sensor systems and / or temperature models. This can be done, for example, by taking into account the gas temperature, the ambient temperature, or other ambient or operating parameters. In a further step, the gas density for the high-pressure region and / or the medium-pressure region can be recorded or stored in the control unit (e.g., in its memory) after the shutdown. Furthermore, the density determination in the high-pressure region and / or the medium-pressure region can be repeated at a time before the valve on the tank container or toward the consumer is opened (at the next start of the motor vehicle).

[0041] Furthermore, density changes in the high-pressure and / or medium-pressure regions can be evaluated. For this purpose, when an increased density is detected in the high-pressure region, a leak in a valve or valves (internal leak) can be inferred, wherein this inference may require a targeted pressure reduction in the pipeline system. If a density reduction is detected in the high-pressure region, a leak from the high-pressure region (external leak) can be inferred, wherein further evaluation can then be performed. For this further evaluation, it can be determined whether a leak is present in the high-pressure region without an increased density in the medium-pressure region, after which an external leak (to the surroundings) from the high-pressure region can be inferred. On the other hand, it can be determined that if a leak in the high-pressure region is accompanied by an increased density in the medium-pressure region, this can be inferred as an internal leak at the control valve between the high-pressure and medium-pressure regions.

[0042] Regarding the medium-pressure region, it can be determined whether there is an increase in density in the medium-pressure region, which indicates possible refilling or leakage through the control valve. Furthermore, a decrease in density in the medium-pressure region can be used to infer a leak from the medium-pressure region. Further evaluation can then be performed. If there is a leak in the medium-pressure region and there is no density change or leak detection in the injection region of the fuel cell (after the anode shutoff valve ASV), an external leak from the medium-pressure region upstream of the fuel cell can be inferred. If a leak in the medium-pressure region is detected along with a density change or leak detection in the fuel cell region, a fuel cell malfunction can be inferred.

[0043] Furthermore, a normally expected density is determined in the medium-pressure region (for the currently existing operating point, for example, taking into account the current operating parameters of the system), for example at a predetermined time or time period, without assuming internal leakage in the control valve. This can be determined from the closing pressure and the minimum temperature of the pressure regulator (control valve) during the idle state, wherein it may be necessary to determine the temperature profile in the high-pressure region and / or the medium-pressure region. This can be differentiated between the cases.

[0044] If the density at the next start-up of the consumer before opening the valve on the tank container or toward the consumer corresponds to the normally expected density in the medium-pressure region, there is probably no internal leakage of the control valve (only normal refilling) and the mass reduction determined in this high-pressure region corresponds to the mass increase in the medium-pressure region, then the state of "no external leakage in the high-pressure and medium-pressure regions" can be additionally inferred.

[0045] If the density at the next start-up before the valve is opened increases compared to the density normally expected in the medium-pressure region, an internal leakage of the control valve is inferred. In this case, a computational evaluation of the control valve leakage can be performed taking into account the density change, the volume in the medium-pressure region (its change), and the duration since the lowest temperature.

[0046] If the density at the next startup, before the valve is opened, corresponds to the "density normally expected in the medium-pressure region," there may be no internal leakage of the control valve (only normal refilling), and the ascertained mass reduction in the high-pressure region is greater than the mass increase in the medium-pressure region, which is greater than the predetermined threshold value. In this case, an "external leakage from the high-pressure region" can also be inferred.

[0047] If the density at the next startup, before the valve is opened, is lower than the "normally expected density in the medium-pressure region," an external leakage from the medium-pressure region can be inferred. In this case, a computational evaluation of the external leakage can be performed taking into account the density changes in the medium-pressure region and the high-pressure region, the medium-pressure region volume and the high-pressure region volume (their changes), and the duration since the shutdown.

[0048] As a supplementary procedure for the check, it can be determined whether the pressure relief valve (PRV) is already open in the idle state, wherein determining the temperature profile may be necessary for this step and / or the temperature may be determined via data exchange via an interconnection service.

[0049] For this purpose, it can be determined whether the density at the time of the next startup before the valve is opened has increased compared to the "normally expected density in the medium-pressure region," and internal leakage of the control valve can be inferred. For this purpose, the maximum pressure during the standstill and the maximum temperature occurring during the standstill can be evaluated mathematically using the determined density in the medium-pressure region before the startup.

[0050] The maximum pressure during the standstill can then be compared with a threshold value stored in the control unit for the minimum closing pressure of the pressure relief valve. If the calculated maximum pressure is greater than or equal to the threshold value, it can be concluded that an external leakage may have occurred due to the opening of the pressure relief valve. Furthermore, a supplementary method can be used to check whether the pressure relief valve has opened during the standstill. For this purpose, a temperature profile can be determined using a wake-up method, which may be necessary. In this wake-up method, the pressure in the medium-pressure region can be measured in addition to the temperature. If one of the measured pressures is greater than or equal to the threshold value, it can be concluded that an external leakage may have occurred due to the opening of the pressure relief valve.

[0051] The high-pressure region can be located upstream of the regulator, toward the tank container. The medium-pressure region can be located between the regulator and the consumer, such as a fuel cell.

[0052] Further features and advantages of the embodiments of the present invention will be apparent from the following description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The invention is explained in more detail below with reference to an exemplary embodiment shown in the schematic representation of the drawing.

[0054] The accompanying drawings show:

[0055] Figure 1 : Schematic diagram of a tank device for storing gaseous fuel for motor vehicles according to one embodiment of the present invention.

[0056] In the figures, the same reference signs denote identical or functionally identical elements. DETAILED DESCRIPTION

[0057] Figure 1 A schematic diagram shows a tank arrangement for storing gaseous fuel for motor vehicles according to a preferred embodiment of the present invention.

[0058] The tank device 1 includes: at least one tank container (TB1, TB2, ..., TBn) having at least one valve device; a gas pipeline system GL, to which the at least one tank container (TB1, TB2, ..., TBn) is connected via a valve device; a first pressure sensor in the high-pressure area and a second pressure sensor in the medium-pressure area of ​​the gas pipeline system GL, wherein the corresponding tank container (TB1, TB2, ..., TBn) is connected to the high-pressure area of ​​the gas pipeline system GL and the high-pressure area is connected to the medium-pressure area via a regulating valve; a control device, which is connected to the pressure sensor and the at least one valve device and is configured to perform the method according to the present invention. In the method, gas discharge from the medium-pressure region of a gas pipeline system is stopped; a first pressure and a first temperature in the high-pressure region are detected by a first pressure sensor, and a second pressure and a second temperature in the medium-pressure region are detected by a second pressure sensor; an average temperature in the medium-pressure region and an average temperature in the high-pressure region are determined based on the determined first and second temperatures; a first reference density in the high-pressure region is determined based on the first pressure and the average temperature in the high-pressure region, and a second reference density in the medium-pressure region is determined based on the second pressure and the average temperature in the medium-pressure region; before gas is again withdrawn from the medium-pressure region of the gas pipeline, the first pressure, the first temperature, the second pressure, and the second temperature in the high-pressure region and the medium-pressure region are re-detected; a current average value of the temperature in the medium-pressure region and the high-pressure region is determined from the re-detected first and second temperatures; a current density in the high-pressure region and the medium-pressure region is determined from the current average value of the temperature and the first and second pressures; the current density in the high-pressure region and the medium-pressure region is compared with a corresponding reference density and a deviation between the corresponding current density and the reference density with respect to a leak in the high-pressure region and / or the medium-pressure region is checked according to a predetermined verification rule.

[0059] Figure 1 A system consisting of a hydrogen storage device with a tank arrangement 1 and a fuel cell system BZE is shown.

[0060] Multiple tank containers TB1, TB2, ... are shown here symbolically as a single tank, which can be connected to a safety valve SV, for example, a heat-activated safety valve, and to a shutoff valve 2. The tank side TS (for example, facing a filling station) can be connected to the tanks TB1, ... via a check valve RSV. The shutoff valve can be connected to the fuel cell BZ in the fuel cell system BZE via a regulator R, in particular via a gas line GL. The gas line GL itself can have a sensor Si on the high-pressure side, that is, upstream of the regulator in the flow direction. Such pressure and / or temperature sensors Si can also be present on the fuel cell side, that is, downstream of the regulator R. The fuel cell BZ can be connected to a blower GB and to an exhaust gas area AB. The fuel cell can then supply an energy management system D, for example, via a battery Batt, one or more capacitors C, an associated control unit D-SE, and drive an electric motor M. The high-pressure region can be located upstream of the regulator R, toward the tank container. The medium-pressure region can be located between the regulator R and a consumer, such as the fuel cell.

[0061] Although the present invention has been completely described above on the basis of preferred exemplary embodiments, the invention is not restricted thereto but can be modified in many ways and methods.

Claims

1. Method for operating a tank arrangement (1) for storing gaseous fuel for motor vehicles, wherein: The tank device (1) comprises: at least one tank container (TB1, TB2, ..., TBn) having at least one valve device; a gas pipeline system (GL), to which the at least one tank container (TB1, TB2, ..., TBn) is connected via the valve device; a first pressure sensor in the high-pressure region of the gas pipeline system (GL) and a second pressure sensor in the medium-pressure region of the gas pipeline system, wherein the respective tank container (TB1, TB2, ..., TBn) is connected to the high-pressure region of the gas pipeline system (GL) and the high-pressure region is connected to the medium-pressure region via a regulating valve; and a control device connected to the pressure sensor and the at least one valve device; The method comprises the following steps: - stopping the discharge of gas from said medium-pressure region (MD) of said gas pipeline system (GL); detecting a first pressure in the high-pressure region and a first temperature in the high-pressure region by means of the first pressure sensor, and detecting a second pressure in the medium-pressure region and a second temperature in the medium-pressure region by means of the second pressure sensor; - determining an average temperature in the medium-pressure region and an average temperature in the high-pressure region based on the determined first temperature and second temperature; - determining a first reference density in the high-pressure region as a function of the first pressure and the average temperature in the high-pressure region, and determining a second reference density in the medium-pressure region as a function of the second pressure and the average temperature in the medium-pressure region; - re-detecting the first pressure, the first temperature, the second pressure and the second temperature in the high-pressure region and the medium-pressure region before re-taking gas from the medium-pressure region of the gas pipeline; - determining the current average value of the temperatures in the medium-pressure region and the high-pressure region from the newly detected first temperature and the second temperature; - determining the current density in the high-pressure region and the medium-pressure region from the current average value of the temperature and the first pressure and the second pressure; and - comparing the current densities in the high-pressure area and the medium-pressure area with corresponding reference densities and checking for deviations between the current densities and the reference densities with respect to leaks in the high-pressure area and / or the medium-pressure area according to predetermined verification rules. 2 . The method according to claim 1 , wherein a pressure reduction is carried out in the high-pressure region after closing the valve arrangement between the gas line system and the at least one tank container before shutting down the gas consumer. 3 . The method according to claim 2 , wherein the predetermined calibration rule relates to a density increase in the high-pressure region and infers a leak in the valve arrangement from this.

4. The method according to claim 1 , wherein the predetermined verification rule relates to a density reduction in the high-pressure region and the presence of a leak in the high-pressure region is inferred therefrom, wherein: If there is also an increase in density in the medium-pressure region, it is concluded that there is an internal leak in the control valve between the high-pressure region and the medium-pressure region.

5. The method according to claim 1 , wherein the predetermined verification rule relates to a density increase in the medium-pressure region and infers the presence of a refill or a leak on the control valve between the high-pressure region and the medium-pressure region.

6. The method according to claim 1 , wherein the predetermined verification rule relates to a density reduction in the medium-pressure region and the presence of a leak in the medium-pressure region is inferred from this, wherein: If a density change additionally occurs at the inlet of the consumer, a fault is inferred at the consumer, and if no density change is present at the inlet of the consumer, a leak in the medium-pressure region relative to the surroundings is inferred.

7. A method according to any one of claims 1 to 6, in which the pressure and temperature in the high-pressure area and the medium-pressure area are determined by the pressure sensor and by the temperature sensor in the high-pressure area and / or the medium-pressure area and / or by a temperature model for the high-pressure area and for the medium-pressure area over multiple predetermined time points and multiple predetermined time intervals, and / or information about the ambient temperature of the data platform is determined.

8. The method according to claim 1 , wherein it is determined whether a pressure relief valve connecting the medium-pressure region to the surroundings was opened during a static phase between stopping gas extraction and restarting gas extraction, wherein: The pressure and temperature profiles are determined over a plurality of predetermined time points in the medium-pressure region, the temperature profile determined thereby is compared with a temperature value for triggering the pressure relief valve, and the pressure profile determined thereby is compared with a pressure value for triggering the pressure relief valve, and the prevailing conditions for opening the pressure relief valve are inferred therefrom.

9. The method according to claim 7 or 8, wherein the normally expected density in the medium-pressure region is determined by determining the lowest temperature in the medium-pressure region during a predetermined time period after stopping gas extraction and before re-examination of gas, and by determining the pressure when the regulating valve between the high-pressure region and the medium-pressure region is closed.

10. The method according to claim 8 or 9, wherein an internal leak in the regulating valve between the high-pressure region and the medium-pressure region is detected if the density in the medium-pressure region is higher than the normally expected density in the medium-pressure region. 11 . The method according to claim 1 , wherein the mean temperature is determined using a temperature model.

12. A tank device (1) for storing gaseous fuel for a motor vehicle (F), comprising: at least one tank container (TB1, TB2, ..., TBn) having at least one valve device; a gas pipeline system (GL), to which the at least one tank container (TB1, TB2, ..., TBn) is connected via the valve device; a first pressure sensor in the high-pressure region of the gas pipeline system (GL) and a second pressure sensor in the medium-pressure region of the gas pipeline system, wherein the respective tank container (TB1, TB2, ..., TBn) is connected to the high-pressure region of the gas pipeline system (GL) via the valve device and the high-pressure region is connected to the medium-pressure region via a regulating valve; A control device is connected to the pressure sensor and the at least one valve device and is configured to carry out the method according to claim 1 .

13. The tank device (1) according to claim 12, in which the control device can be connected to a fuel cell of the motor vehicle and is configured to determine the gas consumption of the fuel cell required to generate the power of the fuel cell.

14. The tank arrangement (1) according to claim 12 or 13, comprising a plurality of temperature sensors in the high-pressure region and one or more temperature sensors in the medium-pressure region.

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