Method and device for checking the seal of pressure tanks

Abstract

The invention relates to a device for checking the seal of pressure tanks for gases, in particular hydrogen pressure tanks, which are designed for at least 300 bar. The device has a connection for a compressor and can fill the pressure tanks to be checked with a test gas up to a desired test pressure pT; the device comprises at least one test chamber which is designed to receive a pressure tank and in which test gas leaking from the pressure tank filled to the test pressure pT can be collected and detected; and the device can empty the test gas out of the checked pressure tank to a desired residual pressure px. Multiple pressure tanks can be received simultaneously in the device, wherein at least n connections are provided for filling pressure tanks which are to be checked, and at least n-1 connections are provided for emptying pressure tanks which have already been checked, the number n equaling at least 3. Each of the emptying connections is connected to at least one respective filling connection via a corresponding gas line which can be blocked by a controllable valve, and the device is designed such that each pressure tank to be checked can be gradually filled with test gas from an initial pressure p1 up to an increased pressure pn in multiple cycles in that the pressure tanks to be checked can be connected, one after the other in individual cycles, to different checked pressure tanks via the gas lines, and therefore test gas can flow from the checked pressure tanks to the pressure tanks to be checked in each individual cycle.

Description

[0001] METHOD AND DEVICE FOR LEAK TESTING PRESSURE TANKS

[0002] The invention relates to a device for leak testing pressure tanks for gases, in particular hydrogen pressure tanks designed for at least 300 bar, and in particular pressure tanks for commercial vehicles. Furthermore, the invention relates to a method for leak testing such pressure tanks for gases, as well as a valve device for use in such a device or for such a method.

[0003] This device is designed such that it can fill the pressure tanks to be tested with a test gas up to the desired test pressure pT, that it comprises at least one test chamber for accommodating a pressure tank, in which test gas escaping from the pressure tank (20) filled up to the test pressure pT can be collected and detected, and that it can empty the test gas from the tested pressure tanks down to a desired residual pressure px, wherein several pressure tanks can be accommodated in the device (1) simultaneously.

[0004] The pressure tanks mentioned above are used, for example, for storing gas in a gas-powered vehicle. Such a pressure tank usually has a rotationally symmetrical, elongated shape, cylindrical in the middle and closed at both ends by curved pole caps. The pressure tank has a wall enclosing a cavity for storing the gas, as well as a metal connector and a so-called boss at each of the pole caps. The wall usually consists of a reinforcement layer made of fiber-reinforced plastic and an internal liner for sealing. The reinforcement layer is preferably wound and designed as a CFRP layer. CFRP stands for carbon fiber reinforced plastic. The liner is made of thermoplastic, for example. Such pressure tanks with a plastic liner are referred to as Type IV.

[0005] Gas-powered vehicles, for example, are powered by a gas engine or a fuel cell with an electric motor. To store sufficient fuel, the gas, which can often be hydrogen, is stored under high pressure in a pressure tank. Pressures of over 300 bar, often up to 700 or 800 bar, are typical for such pressure tanks. For safe operation, it is important that the pressure tank is sufficiently leak-tight. Therefore, it is mandatory that all pressure tanks be individually tested for leaks after production.

[0006] A device and method for testing pressure tanks for gases is known, for example, from EP 3746762 A1. The pressure tank is placed in a test container, filled with a test gas, and brought to the desired test pressure before measurements are taken. The intended measurement variable is elastic deformation of the pressure tank.

[0007] Another device and method for the industrial leak testing of pressure vessels, for example pressure tanks, is known from EP 2994736 A1. It describes how the test object is fed to the leak testing device via conveyor systems and positioned in a test chamber using a handling system. The test chamber and the test object are then evacuated, and subsequently, the test object is pressurized with a test gas on one side, either inside or outside, i.e., inside the test chamber. Once the desired test pressure is reached, a gas sample is taken from the other side (inside or outside) and tested to determine whether test gas can be detected. Examples of test gases used include helium or forming gas (a mixture of a small proportion of H2 and a large proportion of N2).The proposed improvements primarily relate to reducing measurement errors due to contamination of the test chamber with test gas, which might lead to incorrectly assuming a leak in the test object. At the same time, the test sequence should be accelerated when performing serial tests on multiple test objects one after the other. One application example is the leak testing of car rims. This requires only comparatively low pressures of less than 10 bar.

[0008] A problem with industrial leak testing of pressure tanks, especially hydrogen pressure tanks for gas-powered vehicles, is that the pressure tank must be filled to the operating pressure of 300 to 700 or 800 bar before testing and emptied again after the test, which significantly extends the actual test cycles. Leak testing of all pressure tanks in series production therefore requires a significant amount of time or the installation of numerous test devices to meet the needs of a production facility. In particular, the test chambers with the corresponding sensors and evaluation units in a test facility are expensive and complex to maintain.

[0009] The object of the invention is to develop an improved device and an improved method for the leak testing of such pressure tanks, which enables a reliable leak test with less effort and fewer testing devices.

[0010] The object is achieved for the device by the embodiment according to claim 1. Further advantageous features are mentioned in the dependent claims. The embodiment according to the invention is characterized in that at least n connections (F1 ... F9 / Fn)) for filling pressure tanks to be tested and at least n-1 connections (E1 ... E8 / E(n-1) ) for emptying pressure tanks that have already been tested are provided and the number n is at least n=3, wherein each of these connections (E1 ... E8 / E(n-1) ) for emptying is connected to at least one connection (F1 ... F9 / Fn)) for filling via a corresponding gas line that can be shut off with a controllable valve.In addition, the device is designed in such a way that each pressure tank to be tested can be gradually filled with test gas in several cycles from a pre-pressure p1 up to an increased pressure pn by being connected successively in individual cycles to various tested pressure tanks via the gas lines and thus test gas from the tested pressure tanks can flow into the pressure tank to be tested in each individual cycle.

[0011] The drain ports are each assigned to a drain position, and the fill ports are each assigned to a fill position. Furthermore, an Ex port can be provided, to which a tested pressure tank that has already been partially drained can be connected in order to drain it to a residual pressure px.

[0012] The advantage of this design is that a pressure tank to be tested is filled gradually in several cycles by repeatedly connecting it to a previously tested pressure tank which has an even higher pressure, allowing test gas from the pressure tank being tested to flow into the pressure tank to be filled. The device is designed so that several pressure tanks are connected to the device at the same time, so that several pressure tanks at different pressure levels are filled slightly further during one cycle. Once a pressure tank is filled to the test pressure pT, it is placed in the test chamber and tested for leaks. By filling several pressure tanks in parallel while one pressure tank is being tested in the test chamber, the device is much more efficient than previously known devices.

[0013] In addition, the pressure in the previously tested pressure tank is cleverly used to partially fill the pressure tanks to be tested with test gas. In conventional devices, the test gas is completely discharged into a storage tank and then has to be forced back into the pressure tanks to be tested using a compressor from a low pressure in the storage tank. Filling the pressure tanks completely with the compressor takes longer and also requires more energy.

[0014] It is particularly advantageous if each of the connections (E1 ... E8 / E(n-1) ) for emptying is connected to several connections (F1 ... F9 / Fn) ) for filling, in particular if each of the connections (E1 ... E8 / E(n-1) ) for emptying is connected to each of the connections (F1 ... F9 / Fn) ) for filling, via a corresponding gas line that can be shut off with a controllable valve. With such a design, several pairs can be formed by connecting a pressure tank to be tested and a tested pressure tank to each other. A tested pressure tank with a higher pressure is always connected to a pressure tank to be tested with a lower pressure by opening the corresponding gas line via the controllable valve. This allows test gas to flow between the two connected pressure tanks until the pressure is equalized. In this way, a tested pressure tank is emptied somewhat further and a pressure tank to be tested is filled somewhat further.By cyclically switching the valves and thus repeatedly forming appropriate pairs, the pressure tanks being tested are gradually emptied and the pressure tanks to be tested are gradually filled to the increased pressure pn. This allows for even more efficient use of the device, as the pressure tanks do not need to be reassembled and transported between different connections.

[0015] In a preferred embodiment, the controllable valves and at least part of the corresponding gas lines are designed as a valve block. This makes this part compact and less susceptible to failure due to assembly errors or leaky screw connections.

[0016] A further advantageous embodiment has a number n of at least n=5, preferably at least n=7, particularly preferably at least n=9. The more connections there are, the more pressure tanks can be accommodated in the device or connected to it at the same time. The device is therefore not only more time-efficient, as more pressure tanks can be filled in parallel, it is also more energy-efficient, as the pressure tanks are filled in more cycles and thus in smaller pressure stages. The final pressure increase, which occurs with the help of the compressor, is therefore also smaller and therefore requires less energy. The pressure from the pressure tanks being tested is thus better utilized. This is a considerable advantage, especially for pressure tanks with high test pressures (e.g. 700 or 800 bar).An upper limit for the number n results from how small a pressure stage, i.e. the pressure increase achieved in one cycle, can reasonably be.

[0017] The embodiment according to the invention can comprise a compressor which can be connected via the connection (K) to at least one connection (F1 ... F9 / Fn)) for filling, preferably to all connections (F1 ... F9 / Fn)) for filling, and which is designed and connected in such a way that the pressure in a pressure tank to be tested can be brought from the increased pressure pn to the test pressure pT. The connection between the connection (K) and the filling connections can be specifically controlled via further controllable valves so that only one connection for filling is ever connected to the connection (K). This means that each pressure tank accommodated in the device can be connected to the compressor regardless of its position.

[0018] Additionally, it is advantageous to have a test gas reservoir connected to the compressor, into which test gas can be released from a tested pressure tank. This allows the test gas remaining in a tested pressure tank after the last cycle to be recovered and fed via the compressor to a pressure tank being tested.

[0019] In a preferred embodiment of the invention, a control system is present in the device which can switch the valves in cycles in order to release desired gas lines for the respective cycle and to shut off unwanted gas lines, wherein the control system is designed in such a way that it can control a cycle with at least n different cycles with different valve control.

[0020] During the n cycles, each pressure tank is successively brought from the pre-pressure p1 to the test pressure pT at each of the n filling connections. The pressure tank, filled to the test pressure pT, is disconnected from the connection and brought into the test chamber. In its place, a new pressure tank to be tested with the pre-pressure p1 is connected to the freed filling connection.

[0021] Furthermore, it is advantageous if this control is designed such that, in a respective cycle, it releases exactly one connection to a connection (F1 ... F9 / Fn)) for filling for each connection (E1 ... E8 / E(n-1)) for emptying, and in particular releases a connection to port K for a compressor for a connection (F1 ... F9 / Fn)) for filling. The residual emptying of a tested pressure tank, which has reached the lowest pressure level after several cycles, then takes place at a separate connection Ex for residual emptying. In this way, the residual pressure px is reached.

[0022] In a further advantageous embodiment, the device provides a mounting for a pressure tank in this emptying position for each connection (E1 ... E8 / E(n-1)), and a mounting for a pressure tank in this filling position for each connection (F1 ... F9 / Fn)). This ensures a secure connection between the pressure tanks and the connections. In particular, this mounting can also be used to transport the pressure tanks to the respective position.

[0023] For the method, the object is achieved by an embodiment according to claim 10. The inventive method for leak testing is carried out in a device in which the pressure tanks to be tested are filled with a test gas up to the desired test pressure pT, a pressure tank is accommodated in at least one test chamber, and the test gas escaping from the pressure tank filled up to the test pressure pT is collected and detected, and in which the test gas is emptied from the tested pressure tanks down to a desired residual pressure px, wherein several pressure tanks are accommodated in the device simultaneously. The method is characterized in that it is carried out with a device according to the invention having at least n connections (F1 ... F9 / Fn) for filling pressure tanks to be tested and at least n-1 connections (E1 ...E8 / E(n-1) ) for emptying pressure tanks which have already been tested, and the number n is at least n=3, wherein each of these connections (E1 ... E8 / E(n-1 ) ) for emptying is connected to at least one connection (F1 ... F9 / Fn)) for filling via a corresponding gas line which can be shut off with a controllable valve, and wherein a pressure tank is connected to each of these connections (E1 ... E8 / E(n-1 , F1 ... F9 / Fn). Furthermore, it is characterized in that in the method each pressure tank to be tested is gradually filled with test gas in several cycles from a pre-pressure p1 up to an increased pressure pn by connecting it one after the other in individual cycles to different tested pressure tanks via the gas lines and test gas from the tested pressure tanks flows into the pressure tank to be tested in each individual cycle.

[0024] The resulting advantages for the process have already been mentioned in the device.

[0025] In particular, the pressure tank to be tested can be brought from the increased pressure pn to the test pressure pT in a further cycle by further filling it with test gas using a compressor. This means that in one cycle, each of the n-1 discharge ports is connected to one of the filling ports, allowing test gas to flow over, and the remaining filling port is connected to port K on the compressor to continue filling and achieve the final pressure increase from the pressure pn to the test pressure pT.

[0026] Furthermore, it is advantageous if the method is implemented in such a way that a cycle consisting of at least n different cycles, each with a different valve control, is run through. The advantage of the n cycles has already been described in the device.

[0027] Furthermore, the object is also achieved by a valve unit according to claim 13. The valve unit is intended for use in a device according to the invention. It comprises at least n connections (F1 ... F9 / Fn)) for filling pressure tanks to be tested and at least n-1 connections (E1 ... E8 / E(n-1)) for emptying pressure tanks (20') that have already been tested, wherein the number n is at least n=3, and wherein each of the connections (E1 ... E8 / E(n-1)) for emptying is connected to a plurality of connections (F1 ... F9 / Fn)) for filling, in particular each of the connections (E1 ... E8 / E(n-1)) for emptying is connected to each of the connections (F1 ... F9 / Fn)) for filling, via a corresponding gas line that can be shut off with a controllable valve. Furthermore, it comprises a connection (K) for a compressor, which can be connected to at least one, preferably to all connections (F1 ... F9 / Fn)) for filling.The valve unit has a valve block that includes the controllable valves and at least some of the corresponding gas lines. And it includes a controller that can switch the valves in cycles to release desired gas lines for the respective cycle and to shut off unwanted gas lines. The controller is designed such that, in a respective cycle, for each connection (E1 ... E8 / E(n-1)) for emptying, it releases exactly one connection to a connection (F1 ... F9 / Fn)) for filling, and in particular, it releases a connection to a compressor to a connection (F1 ... F9 / Fn)) for filling, and that it can control a cycle with at least n different cycles with different valve controls.

[0028] The resulting advantages for the valve unit have already been mentioned in the device.

[0029] Furthermore, it is advantageous if the valve unit has a connection for a compressor that can be connected to at least one, preferably all, connections (F1 ... F9 / Fn) for filling. Thus, in any filling position in the device, a pressure tank can be filled from the increased pressure pn to the test pressure pT using the compressor, without the pressure tanks having to be reassembled for this cycle and transported between different positions.

[0030] Further advantageous features of the invention are explained using exemplary embodiments with reference to the drawings. These features can be advantageously implemented not only in the illustrated combination, but also individually and advantageously combined with one another. The figures show in detail:

[0031] Fig.1 Schematic representation of an example of a device according to the invention with n=3

[0032] Fig.2a Further embodiment of a device according to the invention (n=3) Fig.2b Embodiment with valve block

[0033] Fig.2c Embodiment with integration of the connection for residual emptying Fig.3a Representation of a possible pressure distribution at the beginning of a first cycle Fig.3b Representation of a possible pressure distribution after a first cycle Fig.3c Representation of a possible pressure distribution at the beginning of a second cycle Fig.3d Representation of a possible pressure distribution after a second cycle

[0034] Fig.4a Embodiment of a device according to the invention with n=9 and representation of a possible pressure distribution at the beginning of a first cycle Fig.4b Representation of a possible pressure distribution after a first cycle (n=9)

[0035] The figures are described in more detail below. Like reference numerals indicate like or similar parts or components.

[0036] Fig. 1 shows a schematic representation of a possible embodiment of the device 1 according to the invention with the number n = 3. The device 1 comprises three connections F1, F2, F3 for filling and two connections E1, E2 for emptying. A pressure tank 20, 20' is connected to each of these connections. Shown here is the simplest possible piping of the device, in which each connection E for emptying is connected to a connection F for filling via a gas line 4 and a controllable valve 5. This means that fixed pairs are formed between the connections E and F which are connected to one another. If different pressure tanks 20, 20' are to be connected to one another one after the other, these pressure tanks must be reassembled from one connection E, F to the next connection E, F, for example from F3 to F2 and then to F1, or from E1 to E2.In addition, there is the connection K which has a connection via the further gas line 8 to the compressor 15 and is connected to one of the connections F for filling, here with F1.

[0037] Furthermore, the test chamber 10 is provided, which can accommodate a pressure tank 20, 20' for leak testing. Any leaks are detected by the detection unit 11 using a suitable sensor. Such detection units 11 can, for example, extract gas from the test chamber and examine it for traces of the test gas. A cycle, for example, runs as described below:

[0038] A tested pressure tank 20', which is filled with the test gas up to the test pressure pT, releases test gas from port E1 to an already partially filled pressure tank 20 to be tested at port F2, until the same pressure, namely the increased pressure pn, prevails in both pressure tanks 20, 20'. A tested pressure tank 20' with the increased pressure pn, which was already partially emptied in the previous cycle, releases test gas from port E2 to a pressure tank 20 to be tested at port F3 with the pre-pressure p1, until the same pressure prevails in both pressure tanks 20, 20'. The pressure tank 20 at port F1 is further filled with the aid of the compressor and brought from the increased pressure pn to the desired test pressure pT. Meanwhile, a pressure tank 20, 20', which was filled to the test pressure pT in a previous cycle, is tested for leaks in the test chamber 10.Another pressure tank 20', which has already been tested and emptied in the device, is completely emptied at connection Ex by releasing the remaining test gas into the storage tank 16 via the discharge line 9 and an optional fine filter, up to a residual pressure px. The compressor 15 pumps the test gas from the storage tank 16 into a pressure tank 20 to be filled.

[0039] For the next cycle, in the design shown, pressure tanks 20, 20' must be reassembled as described above. Pressure tank 20, which was mounted at port F1 and is now at the test pressure pT, goes into the test chamber, pressure tank 20', which was mounted at port E2 and is partially empty, goes to port Ex for residual emptying. Pressure tank 20', which was completely emptied at port Ex, has been fully tested, is emptied, and leaves the device. The tested pressure tank 20' from test chamber 10 goes to port E1, and the pressure tank 20' from port E1 goes to port E2. The pressure tank from F2 goes to F1, the one from F3 goes to F1, and a new pressure tank 20 to be tested is connected to port F3.

[0040] The individual pressure tanks 20, 20' are positioned on optionally available supports 2, 3 so that they can be securely connected to the ports E, F. The supports 2, 3 can, in particular, be designed such that they are suitable for transporting the pressure tanks 20, 20' into or out of the device.

[0041] Fig.2a also shows an embodiment of the device 1 according to the invention with the number n=3. Here, each of the connections E for emptying is connected to each of the connections F for filling via a gas line 4 with a controllable valve 5.

[0042] In addition, each of the connections F can be connected to the connection K for filling, so that each of the connected pressure tanks 20 can be brought to the test pressure pT by the compressor regardless of its position.

[0043] This eliminates the need to reassemble the pressure tanks 20, 20' between cycles. By appropriately controlling the valves 5, the desired pairs of a pressure tank 20 to be tested, which is to be filled, and already tested pressure tanks 20', which are to be emptied, can now be connected. Fig. 2b shows an alternative embodiment in which the gas lines 4 and the valves 5 are combined in a valve block 6. The controller 7 is designed such that it can control the valves 5 and, if necessary, further valves, for example, in the connection to the compressor 15 or the storage tank 16, in such a way that the desired connections are established for a respective cycle and undesired connections are blocked. Together with the controller 7 and the corresponding connections E, F, the valve block 6 forms the valve device 12 according to the invention.

[0044] The connection Ex for residual emptying can optionally be provided as a further connection En for emptying in the device 1 or on the valve block 6, wherein the latter is then designed such that a connection, switchable via additional valves, can be established from each of the connections En to the emptying line 9 and to the storage tank 16. This is analogous to how this is realized with the connection to the compressor 15. Shown in Fig. 2c. For a better understanding of the method according to the invention and the cycles carried out thereby, the pressures in the pressure tanks 20, 20' before and after individual cycles are shown as examples in Figs. 3a-d.

[0045] Fig. 3a shows the condition before the first stroke. The pressures are given here as percentages of the test pressure pT=100%. Assuming equal pressure levels and a pre-pressure of p1 = 10%, the intermediate pressure levels for n=3 are exemplary at 40% and pn=70%.

[0046] The initial situation before the beat is:

[0047] A pressure tank 20 to be tested, which is filled with the test pressure pT, is brought into the test chamber 10. At port E1 there is a pressure tank 20', already tested, coming from the test chamber and still filled with the test pressure pT. At port E2 there is a pressure tank 20', partially emptied in the previous cycle, at the pressure level pn=70%. At port Ex there is a pressure tank 20', which has been emptied even further, at the pressure level 40%. At port F1 there is a pressure tank 20, which has already been filled to the increased pressure pn=70%. At port F2 there is a pressure tank 20, which was partially filled in the previous cycle, at the pressure level 40%. And at port F3 there is a pressure tank 20, which has been newly added to the device and has the pre-pressure p1 = 10%.

[0048] Now, in this cycle, the following pairs are connected by controlling the corresponding valves 5 using the control system:

[0049] Connection E1 with F2, connection E2 with F3, and connection F1 with K.

[0050] Due to the higher pressure level, the test gas from the pressure tanks 20' being tested flows into the pressure tanks 20 to be tested until pressure equalization is achieved. Meanwhile, the pressure tank 20 is tested for leaks in the test chamber 10. Such a leak test can take, for example, 5 to 30 minutes.

[0051] The state after this cycle is shown in Fig. 3b: A tested pressure tank 20' is removed from the test chamber 10. At port F1 there is a pressure tank 20' which is filled to the test pressure pT and can then be introduced into the test chamber 10. At ports F2 and E1 there are pressure tanks 20, 20' each, which are at a pressure level of 70% after pressure equalization. At ports F3 and E2 there are pressure tanks 20, 20' which are at a pressure level of 40% after pressure equalization. The pressure tank 20' at port Ex is emptied to the residual pressure px and can be removed from the device as a tested pressure tank. The residual pressure px should be higher than or equal to the pressure pO in the storage tank so that the test gas flows into the storage tank 16 via the residual emptying line 9. A fine gas filter is optionally provided here.

[0052] In preparation for the next cycle (see Fig. 3c), the pressure tank 20, filled to the test pressure pT, is introduced from port F1 into the test chamber. A new pressure tank 20 to be tested, which has a pre-pressure p1 of 10%, is connected to the thus released port F1. The largely emptied pressure tank 20' at port E2 is removed and connected to port Ex for residual discharge. The tested pressure tank 20' from the test chamber, still filled to the test pressure pT, is connected to the released port E2.

[0053] In the following second cycle, ports E1 and F3, as well as E2 and F1, are connected to each other by controlling the corresponding valves 5, so that pressure equalization can occur in each case. Port F2 is connected to port K to fill pressure tank 20 to the test pressure pT. The pressure tank at port Ex is emptied to the residual pressure px. Meanwhile, pressure tanks 20, 20' are tested for leaks in test chamber 10. Fig. 3d shows the state after this second cycle.

[0054] A third analog clock then connects, after appropriate

[0055] Preparation as described above, the connections E1 with F1, as well as E2 with F2 and F3 with K. After that the cycle with n clock cycles is completed and a new one begins again with the control of the first clock cycle.

[0056] The essential advantage of the invention is that the test gas present at test pressure pT in the tested pressure tank 20' is used in several successive cycles to fill the pressure tanks 20 to be tested with test gas up to the increased pressure pn, so that only the final pressure increase from pn to pT needs to be performed with the aid of the compressor 15. This makes the device and method much more efficient, as energy is saved, the test gas is utilized optimally, and the investment costs and space requirements of the device are lower.

[0057] Furthermore, after a test in test chamber 10, there is no need to wait for the next pressure tank 20 to be filled from the initial pressure p1 to the test pressure pT, since in each cycle only the pressure increase from the increased pressure pn to the test pressure needs to occur. This means that the sequence of the leak test can be adapted to the duration of the leak test in test chamber 10 and is not determined by the time required to fill the pressure tanks.

[0058] Figures 4a and b show a device 1 according to the invention with the number n=9 or any desired number n. The device 1 in turn has a valve unit 12 with a valve block 6, which comprises the controllable valves 5 and the gas lines 4.

[0059] As an example, the pressure levels are shown for a device 1 with n=9, assuming that the pressure levels are evenly distributed and the pre-pressure p1 = 10%. This means that the intermediate levels are distributed in 10% increments between 20% and pn=90%.

[0060] Fig. 4a shows the pressure levels for the condition before the first cycle. During the first cycle, the following connections are connected via the control of valves 5: E1 to F2, E2 to F3, E8 to F9, and F1 to K. Ex is connected to the storage tank 16 via the discharge line 9.

[0061] After the first cycle, i.e. after the pressure equalization of the interconnected pressure tanks 20,20', the pressure levels are as shown in Fig.4b.

[0062] This is followed by further cycles, as previously described for n=3. After 9 cycles, each with a different control of valves 5, the cycle is complete and begins again with the first cycle. For any number n, there are correspondingly n cycles with different control.

[0063] List of reference symbols

[0064] 1 device for leak testing

[0065] 2 Storage for emptying position

[0066] 3 Storage for filling position

[0067] 4 Gas line

[0068] 5 controllable valve

[0069] 6 Valve block

[0070] 7 Control

[0071] 8 additional gas pipelines

[0072] 9 Drain line

[0073] 10 test chamber

[0074] 11 Detection unit with sensor

[0075] 12 valve unit

[0076] 15 Compressor

[0077] 16 storage tanks

[0078] 20 pressure tank to be tested

[0079] 20' tested pressure tank

[0080] E1 - E8 / E(n-1) Connection for emptying Ex Connection for residual emptying

[0081] F1 - F9 / Fn Connection for filling K Connection for a compressor n Number of connections for filling n-1 Number of connections for emptying pO Pressure in the storage tank p1 Pre-pressure pn Increased pressure pT Test pressure px Residual pressure

Claims

Patent claims 1. Device (1) for the leak testing of pressure tanks (20, 20') for gases, in particular hydrogen pressure tanks designed for at least 300 bar, which device has a connection (K) for a compressor (15) and can fill the pressure tanks (20) to be tested with a test gas up to the desired test pressure pT, which device comprises at least one test chamber (10) for accommodating a pressure tank (20), in which test gas escaping from the pressure tank (20) filled up to the test pressure pT can be collected and detected, and which can empty the test gas from the tested pressure tanks (20') up to a desired residual pressure px, wherein several pressure tanks (20, 20') can be accommodated in the device (1) or connected to it simultaneously, characterized in that at least n connections (F1 ... F9 / Fn)) for filling pressure tanks (20) to be tested and at least n-1 connections (E1 ...E8 / E(n-1) ) for emptying pressure tanks (20') which have already been tested, and the number n is at least n=3, wherein each of these connections (E1 ... E8 / E(n-1) ) for emptying is connected to at least one connection (F1 ... F9 / Fn)) for filling via a corresponding gas line (4) which can be shut off with a controllable valve (5), and wherein the device (1 ) is designed such that each pressure tank (20) to be tested can be filled with test gas gradually in several cycles from a pre-pressure p1 up to an increased pressure pn by being able to connect it successively in individual cycles to different tested pressure tanks (20') via the gas lines (4) and thus test gas from the tested pressure tanks (20') can flow into the pressure tank (20) to be tested in each of the individual cycles.

2. Device (1) according to claim 1, characterized in that each of the connections (E1 ... E8 / E(n-1)) for emptying is connected to a plurality of connections (F1 ... F9 / Fn)) for filling, in particular that each of the connections (E1 ... E8 / E(n-1)) for emptying is connected to each of the connections (F1 ... F9 / Fn)) for filling, via a corresponding gas line (4) which can be shut off with a controllable valve (5).

3. Device (1) according to one of claims 1 or 2, characterized in that the controllable valves (5) and at least part of the corresponding gas lines (4) are designed as a valve block (6).

4. Device (1) according to one of the preceding claims, characterized in that the number n is at least n=5, preferably at least n=7, particularly preferably at least n=9.

5. Device (1) according to one of the preceding claims, characterized in that a compressor (15) is present which can be connected via the connection (K) to at least one connection (F1 ... F9 / Fn)) for filling, preferably to all connections (F1 ... F9 / Fn)) for filling, and which is designed and connected in such a way that the pressure in a pressure tank (20) to be tested can be brought from the increased pressure pn to the test pressure pT.

6. Device (1) according to claim 5, characterized in that a storage tank (16) for test gas is provided, which is connected to the compressor (15) and into which test gas can be discharged from a tested pressure tank (20').

7. Device (1) according to one of the preceding claims, characterized in that a control (7) is provided which can switch the valves (5) in a cyclic manner in order to release desired gas lines (4) for the respective cycle and to shut off unwanted gas lines (4), the control being designed in such a way that it can control a cycle with at least n different cycles with different valve control.

8. Device (1) according to claim 7, characterized in that the control is designed such that it releases in a respective cycle for each connection (E1 ... E8 / E(n-1)) for emptying exactly one connection to a connection (F1 ... F9 / Fn)) for filling, and in particular releases a connection to the connection (K) for a compressor (15) for a connection (F1 ... F9 / Fn)) for filling.

9. Device (1) according to one of the preceding claims, characterized in that for each connection (E1 ... E8 / E(n-1)) for emptying there is a bearing (2) for a pressure tank (20') in this emptying position and for each connection (F1 ... F9 / Fn)) for filling there is a bearing (3) for a pressure tank (20) in this filling position.

10. A method for leak testing pressure tanks (20; 20') for gases, in particular hydrogen pressure tanks designed for at least 300 bar, carried out in a device (1) in which the pressure tanks (20) to be tested are filled with a test gas up to the desired test pressure pT, a pressure tank (20) is accommodated in at least one test chamber (10), and the test gas escaping from the pressure tank (20) filled up to the test pressure pT is collected and detected, and in which the test gas is emptied from the tested pressure tanks (20') down to a desired residual pressure px, wherein several pressure tanks (20, 20') are accommodated in the device (1) or connected to them simultaneously, characterized in that that the device (1) is designed according to one of the preceding claims, in that it has at least n connections (F1 ... F9 / Fn)) for filling pressure tanks (20) to be tested and at least n-1 connections (E1 ... E8 / E(n-1)) for emptying pressure tanks (20') that have already been tested, and the number n is at least n=3, wherein each of these connections (E1 ... E8 / E(n-1)) for emptying is connected to at least one connection (F1 ... F9 / Fn)) for filling via a corresponding gas line (4) that can be shut off with a controllable valve (5), and wherein at each of these connections (E1 ... E8 / E(n-1, F1...F9 / Fn) a pressure tank (20, 20') is connected, and in that in the method each pressure tank (20) to be tested is gradually filled with test gas in several cycles from a pre-pressure p1 to an increased pressure pn by being connected successively in individual cycles to various tested pressure tanks (20') via the gas lines (4) and test gas from the tested pressure tanks (20') flows into the pressure tank (20) to be tested in each individual cycle.

11. Method according to claim 10, characterized in that the pressure tank (20) to be tested is brought from the increased pressure pn to the test pressure pT in a further cycle by further filling it with test gas with the aid of a compressor (15).

12. Method according to one of claims 10 and 11, characterized in that a cycle of at least n different cycles is run through, each with a different valve control of the valves (5).

13. Valve unit (12) for a device (1) according to one of claims 1 to 9, comprising at least n connections (F1 ... F9 / Fn)) for filling pressure tanks (20) to be tested, and at least n-1 connections (E1 ... E8 / E(n-1)) for emptying pressure tanks (20') that have already been tested, wherein the number n is at least n=3, and wherein each of the connections (E1 ... E8 / E(n-1)) for emptying with several connections (F1 ... F9 / Fn)) for filling, in particular each of the connections (E1 ... E8 / E(n-1 )) for emptying is connected to each of the connections (F1 ... F9 / Fn)) for filling, via a corresponding gas line (4) which can be shut off with a controllable valve (5), a connection (K) for a compressor (15) which can be connected to at least one, preferably to all connections (F1 ... F9 / Fn)) for filling, a valve block (6) which comprises the controllable valves (5) and at least some of the corresponding gas lines (4), and a control (7) which can switch the valves (5) in cycles in order to release desired gas lines (4) for the respective cycle and to release undesired to shut off gas lines (4), wherein the control (7) is designed such that in a respective cycle for each connection (E1 ... E8 / E(n-1 ) ) for emptying it releases exactly one connection to a connection (F1 ... F9 / Fn)) for filling, and in particular releases a connection to a compressor (15) to a connection (F1 ... F9 / Fn)) for filling, and that it can control a cycle with at least n different cycles with different valve control.

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