Method for diagnosing the state of a tank system, and tank system

Abstract

The invention relates to a method (100) for diagnosing the state of a tank system (200) which comprises a plurality of tanks (201, 203). The method (100) has the following steps: - storing (101) an initial pressure in a high-pressure line (217) which connects the plurality of tanks (201, 203), - opening (103) the tank (201) having the lowest temperature of all tanks (201, 203) of the plurality of tanks (201, 203), - determining (105) a stabilization duration from when the tank (201) is opened up to a reference time at which the rate of change of the pressure is less than a specified reference threshold value, - storing (107) a reference pressure determined in the high-pressure line (217) at the reference time, and - outputting (109) a notification which indicates an open state of an excess flow valve (EFV) of the open tank (201) in the event the difference between the initial pressure and the reference pressure is greater than a specified pressure threshold value or the stabilization duration is greater than a specified time threshold value.

Description

[0001] Description

[0002] title

[0003] Methods for diagnosing the condition of a tank system and tank system

[0004] The presented invention relates to a method for diagnosing the condition of a tank system and to a tank system.

[0005] State of the art

[0006] To power mobile applications with hydrogen, these applications must be able to carry the hydrogen with them. For this purpose, the hydrogen is usually stored in more than one tank, both to allow for flexible and space-saving placement of the tanks within a vehicle and to increase the vehicle's range.

[0007] Therefore, it is common practice to install tank systems with more than two tanks in commercial vehicles, ships, trains, etc.

[0008] Tank systems typically include a control unit that provides all the necessary functions for operating such a system. A key task here is to control the tank valves (HTV - Hydrogen Tank Valves) so that the tanks are opened and closed at the correct time.

[0009] Refueling or withdrawing hydrogen from a tank system, as well as leaks, can lead to pressure differences within the tanks. This is caused, among other things, by different tank sizes, varying environmental conditions, and throttling effects in the lines during refueling or withdrawal. These pressure differences can cause excess flow valves (EFVs) to activate when the tank valves are opened or are already open. These EFVs are usually integrated into the tank valves and are designed to prevent the escape of high hydrogen mass flows in the event of a malfunction.

[0010] Since EFVs are mostly passive components without feedback information, the condition of the EFVs cannot be directly determined.

[0011] Disclosure of the invention

[0012] Within the scope of the presented invention, a tank system and a method for diagnosing the condition of the tank system are introduced. Further features and details of the invention will become apparent from the respective dependent claims, the description, and the drawings. Features and details described in connection with the method according to the invention naturally also apply in connection with the tank system according to the invention, and vice versa, so that the disclosure of the individual aspects of the invention is always, or can always be, mutually interdependent.

[0013] The presented invention serves in particular to provide a means of detecting an open state of an EFV of a tank in a tank system with multiple tanks.

[0014] Thus, according to a first aspect of the presented invention, a method for diagnosing the condition of a tank system comprising a plurality of tanks is presented.

[0015] The presented method comprises storing an initial pressure in a high-pressure line connecting the multiple tanks, opening the tank with the lowest temperature of all the tanks in the multiple, determining a stabilization period from the opening of the tank until a reference time at which the rate of change of the pressure is less than a predetermined reference threshold, storing a reference pressure present in the high-pressure line at the reference time, and issuing a message indicating an open state of an EFV of the opened tank if the difference between the initial pressure and the reference pressure is greater than a predetermined pressure threshold or the stabilization period is greater than a predetermined time threshold.

[0016] In the context of the presented invention, a stabilization period is understood to be the time that elapses after opening a tank until a pressure in a high-pressure line coupled to the tank is stable, i.e., in particular, has transitioned into a stationary phase.

[0017] In the context of the presented invention, "outputting a message" means displaying the message on an output unit, such as a display, and / or storing the message in a memory, such as an error memory.

[0018] The presented invention is based on the principle that a change in pressure in a high-pressure line connecting several tanks indicates the opening state of an EFV of the tank.

[0019] To determine the opening state of the EFV (Exhaust Valve) of a tank, the stabilization period can be determined and compared to a predefined time threshold. Alternatively, changes in pressure in the high-pressure line can be measured at various times and compared to a predefined pressure threshold.

[0020] Since the stabilization time depends on the cross-section of the connection between the tank and the high-pressure line, it changes depending on the activity of the EFV (Exhaust Flow Valve). Accordingly, if the stabilization time exceeds a predefined time threshold, it can be assumed that the cross-section is constricted by an active EFV, and a corresponding message should be issued.

[0021] Furthermore, since an activated pressure relief valve (PFV) changes the pressure introduced into the high-pressure line through the tank, the PFV's status can also be determined by the difference between the initial pressure when the tank is opened and a reference pressure measured at a time when the pressure in the high-pressure line is stable. Accordingly, if the difference between the initial pressure and the reference pressure exceeds a predefined reference threshold, it can be assumed that the cross-section is constricted by an active PFV, and a corresponding message should be issued.

[0022] It may be planned that the procedure is successively repeated for all tanks of the multitude of tanks.

[0023] In order to exclude the influence of different tanks on the process or to assign a specific pressure measurement to a particular tank, the tanks can be opened successively, i.e., one after the other, so that a measurement is first carried out to determine the state of a first tank and only when the state of the first tank has been determined is a second tank opened to determine its state.

[0024] Accordingly, it may also be provided that if the difference between the initial pressure and the reference pressure is less than or equal to the specified pressure threshold, or if the stabilization period is less than or equal to the specified time threshold, another tank is opened.

[0025] It may also be provided that all tanks are opened by storing the respective temperatures in the tanks when the tanks are opened, determining a change in the respective temperatures over a specified period, and in the event that the difference of a change in the temperature of a respective tank to an average of the changes is greater than a specified temperature threshold, a message is issued indicating an open state of the EFV of the respective tank.

[0026] Due to the reduced flow rate of tanks with active EFV compared to tanks with inactive EFV, these tanks will cool down more slowly. Therefore, once all tanks are opened, the temperature of all tanks can be recorded, and then the temperature changes of all tanks can be continuously measured. These temperature changes can be compared across all tanks or between tanks, and if a deviation in the temperature profile measured for a particular tank from the temperature profiles of other tanks exceeds a predefined temperature threshold, it can be assumed that the EFV of that tank is active.

[0027] It may also be provided that a tank for which the message has been issued is opened by activating a tank valve of the tank in a pulsed manner.

[0028] In the event that the message provided for in the invention is issued for a particular tank, it is known that the EFV (expansion valve) of that tank has been activated, and that this tank therefore has a higher pressure than the other tanks. Consequently, their EFV will be activated again upon the next commissioning. This can be remedied by selectively and, if necessary, pulsedly controlling the tank valve of the tank with the higher pressure, while the tank valves of the lower-pressure tanks are not controlled. This allows the lower-pressure tanks to be refilled by the higher-pressure tank. This can only occur if there is no demand from the connected consumers. It is important to note that this refilling of the tanks must not cause their permissible temperature limit to be exceeded. Therefore, the process can be repeated after the tanks have cooled down.

[0029] It may also be provided that the pressure in a respective tank is determined by means of a pressure sensor arranged on the respective tank.

[0030] If a pressure sensor is installed on a particular tank, the pressure in the tank can be measured directly by the pressure sensor.

[0031] As an alternative to a pressure sensor, the pressure in a given tank can be determined based on the temperature measured by a temperature sensor located on the tank. Since the temperature in a tank correlates with its pressure, the tank's pressure can be inferred from its temperature. This eliminates the need for expensive pressure sensors on the tanks.

[0032] According to a second aspect, the presented invention relates to a tank system for storing hydrogen.

[0033] The presented tank system comprises a plurality of tanks, each containing an EFV, a high-pressure line connecting the tanks, a pressure sensor arranged on the high-pressure line, and a computing unit, the computing unit being configured to execute one possible embodiment of the presented method.

[0034] In the context of the presented invention, a computing unit is to be understood as a computer, a control unit, a processor or any other programmable circuit.

[0035] It may be provided that each tank in the multitude of tanks is equipped with a temperature sensor and not a pressure sensor.

[0036] Alternatively, it can be provided that a pressure sensor is arranged on each tank of the multitude of tanks, in particular a temperature sensor and a pressure sensor.

[0037] Features that are described in detail in relation to the method for diagnosing the condition of a tank system according to the first aspect of the invention apply equally to the tank system for storing hydrogen according to the second aspect of the invention and vice versa.

[0038] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description can be essential to the invention individually or in any combination. Drawings

[0039] They each show schematically:

[0040] Figure 1 shows a possible embodiment of the presented method,

[0041] Figure 2 shows a possible embodiment of the presented tank system, and

[0042] Figure 3 shows a detailed representation of a possible embodiment of the method according to Figure 1.

[0043] Description of the exemplary implementations

[0044] Fig. 1 shows a method 100 for diagnosing the condition of a tank system comprising a plurality of tanks.

[0045] The procedure 100 comprises a first storage step 101, in which an initial pressure is stored in a high-pressure line connecting the plurality of tanks; an opening step 103, in which the tank with the lowest temperature of all the tanks in the plurality is opened; a determination step 105, in which a stabilization period is determined from the opening of the tank until a reference time at which the rate of change of the pressure is less than a predetermined reference threshold; a second storage step 107, in which a reference pressure is stored in the high-pressure line at the reference time; and an output step 109, in which a message reporting an open state of an EFV of the opened tank is issued if the difference between the initial pressure and the reference pressure is greater than a predetermined pressure threshold or the stabilization period is greater than a predetermined time threshold.

[0046] Figure 2 shows a tank system 200 for storing hydrogen. The tank system comprises a first tank 201 and a second tank 203. The first tank 201 includes a first tank valve 205 with a first EFV 207 and a temperature sensor 209.

[0047] The second tank 203 includes a second tank valve 211 with a second EFV 213 and a temperature sensor 215.

[0048] The first tank 201 and the second tank 203 are connected via a high-pressure line 217.

[0049] A pressure sensor 219 is arranged on the high-pressure line 217.

[0050] Furthermore, the tank system 200 includes a computing unit 221, which controls the tank valves 205 and 211 and is communicatively coupled with the sensors 215, 217 and 219.

[0051] The computing unit 221 is configured to perform the procedure 100 according to Fig. 3.

[0052] In Fig. 3, the method 100 is shown in detail using the tank system 200 and starts with an initialization step 301, such as a shutdown process to switch off a consumer.

[0053] In storage step 303, an initial pressure determined by the pressure sensor 219 is stored at a first point in time.

[0054] In opening step 305, the first tank valve 205 of the first tank 201 is opened.

[0055] In step 307, the system waits until the pressure in high-pressure line 217 is stable, i.e., until it is in a steady state at a second time point. The stabilization period between the first and second time points is then determined. A second pressure is then determined at this second time point. In step 309, the difference between the initial pressure and the second pressure is compared to a predefined pressure threshold, or the stabilization period is compared to a predefined time threshold.

[0056] In the event that the difference between the initial pressure and the second pressure is greater than the pressure threshold or the stabilization period is greater than the time threshold, a message is issued in output step 311 reporting an open state of the first EFV 207.

[0057] Otherwise, the second tank 203 is opened and, in a verification step 313, it is checked whether all tanks of the tank system 200 are open. If not, the procedure continues with the storage step 303. Otherwise, in a determination step 315, the temperatures of all tanks are determined and stored, in a calculation step 317, the temperature changes in all tanks are determined, and in a calculation step 319, the changes in the temperature differences between all tanks are calculated.

[0058] In a balancing step 321, it is determined whether the temperature differences between all tanks are greater than a specified temperature threshold for each tank.

[0059] If the change in temperature differences between the tanks exceeds the specified temperature threshold, a message is output in output step 311 indicating that the second EFV 213 is open. Otherwise, procedure 100 continues with determination step 317.

Claims

Claims 1. Method (100) for diagnosing the condition of a tank system (200) comprising a plurality of tanks (201, 203), wherein the method (100) comprises: - Storing (101) an initial pressure in a high-pressure line (217) connecting the multiple tanks (201, 203), - Opening (103) of the tank (201) in which the lowest temperature is present of all the tanks (201 , 203) of the multitude of tanks (201 , 203), - Determining (105) a stabilization period from the opening of the tank (201) until a reference time at which a rate of change of pressure is less than a specified reference threshold, - Storing (107) a reference pressure determined in the high-pressure line (217) at the reference time, - Output (109) of a message reporting an open state of an excess flow valve (EFV) of the open tank (201) if the difference between the initial pressure and the reference pressure is greater than a specified pressure threshold or the stabilization time is greater than a specified time threshold.

2. Method (100) according to claim 1 , characterized in that the method (100) is successively repeated for all tanks (201 , 203) of the plurality of tanks (201 , 203).

3. Method (100) according to claim 1 or 2, characterized in that if the difference of the initial pressure from the reference pressure is less than or equal to the predetermined pressure threshold or the stabilization period is less than or equal to the predetermined time threshold, a further tank (203) of the plurality of tanks (201 , 203) is opened.

4. Method (100) according to claim 3, characterized in that all tanks (201 , 203) of the plurality of tanks (201 , 203) are opened by: - the respective temperatures in the tanks (201, 203) are stored when the tanks (201, 203) are opened, - a change in the respective temperatures is determined over a specified period, and - in the event that the difference between a change in the temperature of a respective tank (201 , 203) and an average of the changes is greater than a specified temperature threshold, a message is issued indicating an open state of the EFV of the respective tank (201 , 203).

5. Method (100) according to one of the preceding claims, characterized in that a tank (201 , 203) for which the message has been issued is opened by actuating a tank valve (205, 211) of the tank (201 , 203) in a pulsed manner.

6. Method (100) according to one of the preceding claims, characterized in that the pressure in a respective tank (201 , 203) is determined by means of a pressure sensor (219) arranged on the respective tank (201 , 203).

7. Method (100) according to one of claims 1 to 5, characterized in that the pressure in a respective tank (201 , 203) is determined on the basis of a temperature determined by means of a temperature sensor (209, 215) arranged on the respective tank (201 , 203).

8. Tank system (200) for storing hydrogen, wherein the tank system (200) comprises: - a plurality of tanks (201, 203), each comprising an excess flow valve (EFV) (207, 213), - a high-pressure line (217) connecting the tanks, - a pressure sensor (219) arranged on the high-pressure line, - a computing unit (221) wherein the computing unit (221) is configured to execute a method (100) according to any one of claims 1 to 7.

9. Tank system (200) according to claim 8, characterized in that a temperature sensor (209, 215) is arranged on each tank (201 , 203) of the plurality of tanks (201 , 203).

10. Tank system (200) according to claim 8 or 9, characterized in that a pressure sensor (219) is arranged on each tank (201 , 203) of the plurality of tanks (201 , 203).

Images