Method for filling gas tank with gas, gas tank and gas tank system

Abstract

The invention relates to a method for filling a storage volume (2) of a gas tank (1) with gas, in which method gas is introduced into the storage volume (2) via a gas filling path (3) with an integrated tank valve (4), the temperature of the gas in the region of a retardation point (7) is detected by means of a sensor (5) integrated in the gas filling path (3), the blocking point is formed by the sensor (5) and / or a holding body (8) accommodating the sensor (5). The invention further relates to a gas tank (1) and to a gas tank system having at least one gas tank (1) according to the invention.

Description

Technical Field

[0001] The present invention relates to a method for filling a gas tank with gas. The gas may be hydrogen or natural gas, for example. Such gas is necessary for fuel cell vehicles or vehicles using gas engines, for example.

[0002] The invention further relates to a gas cylinder for a gas cylinder system and to a gas cylinder system having at least one gas cylinder according to the invention. Background Art

[0003] In vehicles that run on gas, such as hydrogen, the gas is usually stored under pressure in gas tanks. In the case of hydrogen, the pressure can reach 70 MPa. The temperature in the gas tank can rise to 85° C. In this case, the temperature limit is usually predetermined by the material of the gas tank, where carbon fiber reinforced plastic (“CFK”) is often used as the material. When using CFK materials, the plastics, especially synthetic resins, required for fixing the carbon fibers soften above 85° C., so that the required strength of the gas tank is no longer guaranteed.

[0004] Since, for example, hydrogen has a negative Joule-Thomson effect in the relevant temperature range, the hydrogen heats up when filling the gas tank or hydrogen tank. In order to avoid damage to the gas tank, the hydrogen is cooled to about -40°C before the filling process. In addition, the gas tank can be filled with an upwardly bent filling gun, which promotes the mixing of fresh hydrogen with the gas in the tank and thus reduces heating. As an additional measure, the tank temperature can also be measured or monitored so that the filling process can be stopped when the temperature limit is exceeded. In order to strictly adhere to the temperature limit, it must be stopped as early as possible. Therefore, high measurement errors have a negative impact. Since the determination of the mass stored in the gas tank is usually also performed based on the tank temperature, large measurement errors may also lead to incorrect calculation of the tank level or the remaining range.

[0005] Therefore, for both purposes, it is desirable to obtain information about the temperature in the gas tank that is as precise as possible. However, the locally occurring maximum temperature is decisive for compliance with temperature limits, while the average temperature is more suitable for calculating the stored quality. It is difficult to reconcile these two expectations. This is especially because thermocouples, thermistors or temperature resistors are usually used for temperature measurement, which can only detect the temperature in their immediate surroundings. In addition, the choice of sensor position is also strongly restricted due to the limited accessibility of the tank interior.

[0006] For example, US 2010 / 0032934 A1 discloses a gas tank having a tank pipe and a tank valve for filling the gas tank with gas, and a sensor arranged on the tank pipe for detecting a state variable of the gas. The sensor is positioned in such a way that when the gas tank is filled with gas, the sensor is outside the pressure jet formed. In this way, the measuring accuracy of the sensor is to be increased. Summary of the invention

[0007] The invention is directed to the object of ensuring compliance with predefined temperature limits when filling a storage volume of a gas tank with gas in order to avoid overloading of the gas tank.

[0008] In order to achieve this object, a method having the features of claim 1 and a gas cylinder having the features of claim 5 are proposed. Advantageous developments of the invention can be derived from the corresponding dependent claims. In addition, a gas cylinder system having at least one gas cylinder according to the invention is provided.

[0009] In the proposed method for filling a storage volume of a gas tank with gas, the gas is introduced into the storage volume via a filling path with an integrated tank valve. Here, the temperature of the gas in the region of a stagnation point is detected by means of a sensor integrated in the filling path, the stagnation point being formed by the sensor and / or a holder accommodating the sensor.

[0010] Usually, the flow of the gas introduced into the storage volume is first braked or stopped by the wall surrounding the storage volume, which leads to a strong local heating of the gas in the wall area. Local temperature maxima that exceed the permissible limit values ​​may occur here, so that there is a risk of overloading the gas tank. With the proposed method and the artificial blocking points formed inside the filling path, the occurrence of local temperature maxima is shifted away from the wall into the filling path and detected with the help of sensors arranged there. In this way, compliance with the predefined temperature limits can be monitored more simply and more reliably to avoid overloading of the gas tank.

[0011] In a further development of the invention, it is proposed that the measured value of the sensor is compared with a predetermined temperature limit value and that the filling process is stopped or interrupted if the temperature limit value is exceeded. These further steps serve to prevent overloading of the gas tank. The predetermined temperature limit value is preferably also below a limit value predetermined by the material of the gas tank.

[0012] Preferably, the temperature of the gas outside the stagnation point area, for example in the storage volume, is detected by means of a further sensor, and an average value and / or a difference is determined based on the measured values ​​of the two sensors. The sensor arranged in the stagnation point area detects the local temperature maximum or the "total temperature", while the "quiet temperature" can be detected by means of the further sensor. For this purpose, the further sensor is arranged outside the stagnation point area. By averaging, the average temperature in the gas tank can then be inferred from the measured values ​​of the two sensors, which average temperature is necessary for calculating the stored mass. In addition, the flow rate of the gas when filling the storage volume with gas can also be determined by difference determination. Based on the flow rate of the gas, the mass flow rate or the mass of the gas introduced into the storage volume can then be calculated.

[0013] As an improvement measure, it is therefore proposed to deduce the flow velocity of the gas during the filling process from the difference.

[0014] During the filling process, the total temperature differs greatly from the static temperature. This means that the difference between the measured values ​​of the two sensors is large. The opposite is true during the emptying process, provided that the filling path is not also used for emptying. If the difference is small or the measured values ​​of the two sensors are close to each other, this information can be used to verify the plausibility of the emptying process.

[0015] If a significantly higher temperature is observed at the first sensor after the filling process, it can be assumed that an uncontrolled "tank dumping process" has occurred within the gas tank system with several gas tanks. This means that gas from another gas tank has flowed into the gas tank. In this case, the tank valve can be controlled or closed in such a way that a predetermined temperature limit value is not exceeded.

[0016] The first sensor for detecting the total temperature is preferably integrated in the filling path in such a way that it measures only the static part of the temperature when the flow direction of the gas in the filling path is reversed. This means that the first sensor is directly exposed to the flow only in one direction, more precisely in the filling direction. The sensor can be prevented from being directly exposed to the flow in the flow direction opposite to the filling direction, in particular by a retaining body, which can shield the sensor when the flow direction in the filling path is reversed.

[0017] The ratio of the total temperature to the static temperature depends on the specific geometry and / or attachment of the two sensors. Possible errors in the measurement signals of the two sensors can be reduced by calibration, so that the measurement accuracy is further improved.

[0018] Furthermore, a gas tank for a gas tank system is proposed. The gas tank has a storage volume that can be filled with gas via a filling path with an integrated tank valve. Furthermore, the gas tank has a sensor integrated in the filling path for detecting the temperature of the gas, wherein the sensor and / or a holder accommodating the sensor form a blocking point in the filling path, and the measuring area of ​​the sensor is arranged in the area of ​​the blocking point. This means that the temperature of the gas is measured in the area of ​​the blocking point, so that the overall temperature can be detected with the aid of the sensor.

[0019] The proposed gas cartridge can therefore be used to carry out the method according to the invention described above. The same advantages can therefore be achieved with the gas cartridge as with the method according to the invention described above.

[0020] The sensor and / or the holder preferably has an oncoming surface which is oriented substantially perpendicularly to the flow direction of the gas in the filling path when the storage volume is filled with gas. As a result, during filling, the gas stagnates at the oncoming surface, so that the oncoming surface of the sensor and / or the holder forms a stagnation point. In order to detect the temperature of the gas in the region of the stagnation point, the oncoming surface of the sensor preferably simultaneously forms a measuring region of the sensor.

[0021] In a further development of the invention, a further sensor is integrated in the filling path or in the storage volume outside the blocking point area. Since the further sensor is located outside the blocking point area, the static temperature in the gas tank is detected with the aid of the further sensor. From the total temperature measured with the aid of the first sensor and the static temperature measured with the aid of the further sensor, an average value and / or a difference value can be determined. The average value provides information about the average temperature in the gas tank, which is necessary for calculating the stored quality. From the difference value, the flow rate of the gas in the filling direction can be inferred.

[0022] When the further sensor is integrated in the gas filling path, the further sensor is preferably arranged or oriented in such a way that the gas does not flow directly into the further sensor, but the gas flows past the sensor. This is because, unlike the first sensor, the formation of stagnation points in the region of the further sensor is to be avoided. For this purpose, the sensor can be arranged essentially parallel to the flow direction of the gas. Alternatively, the further sensor can be arranged not only outside the stagnation point region, but also outside the gas filling path, so that a stronger consideration of the static temperature is ensured.

[0023] Furthermore, it is proposed that the two sensors are connected via a holding body. The holding body thus facilitates the installation of the sensors.

[0024] Furthermore, the filling path is preferably guided at least in sections through a tube that projects into the storage volume. The tube predetermines the filling direction. Furthermore, the tube has a defined flow cross section that simplifies the formation of a blocking point through the first sensor and / or the retaining body. For this purpose, the first sensor and / or the retaining body are integrated into the tube, more precisely preferably in such a way that the incident flow surface is oriented perpendicularly to the flow direction of the gas in the filling direction.

[0025] Advantageously, the filling path, the tank valve and the at least one sensor form a tank unit, which is inserted, in particular screwed, into a preferably centrally arranged end opening of a wall surrounding the storage volume. As a tank unit, all components can be preassembled and inserted into the gas tank as a preassembled installation unit, thereby simplifying installation. At the same time, installation space can be saved. In addition, the tank unit can also accommodate further components, such as further valves and / or further sensors. In addition, the tank unit can have a tube extending into the storage volume, through which the filling path is passed at least in sections, in particular in an end section of the filling path.

[0026] Furthermore, a gas tank system is proposed, which comprises at least one gas tank according to the invention. For example, a plurality of gas tanks of the same type can be connected in a parallel arrangement via a common frame. The frame facilitates the installation of the gas tank system in a vehicle, for example in a fuel cell vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The preferred embodiments of the present invention are described in more detail below in conjunction with the accompanying drawings. The accompanying drawings show:

[0028] Figure 1 Schematic longitudinal section of a gas tank according to the invention in the region of the tank unit,

[0029] Figure 2 a)-d) are schematic longitudinal sections of a holding body for a gas tank according to the invention with two sensors,

[0030] Figure 3 Schematic longitudinal section of a tube with integrated holding body and two sensors and

[0031] Figure 4 Schematic longitudinal section through a tube with integrated holding body and two sensors. DETAILED DESCRIPTION

[0032] exist Figure 1The gas tank 1 shown in FIG. 1 has a wall 12 surrounding a storage volume 2, which has an end opening 13, into which a tank unit 11 is inserted. A filling path 3 with an integrated tank valve 4 for filling the gas tank 1 with fresh gas passes through the tank unit 11. The end section of the filling path 3 is defined by a pipe 10 extending into the storage volume 2. Since the gas, for example hydrogen, heats up greatly when introduced into the storage volume 2, the temperature of the gas is monitored by means of sensors 5, 6. In this case, the first sensor 5 is used to detect the total temperature and the second sensor 6 is used to detect the static temperature.

[0033] In order to detect the total temperature, i.e. the maximum temperature occurring locally, the first sensor 5 is integrated into the pipe 10 in such a way that it is located in the filling path 3 and directly faces the gas in the filling direction. The gas accumulates on the flow surface 9 of the sensor 5, which is oriented perpendicular to the gas flow direction, so that a stagnation point 7 is formed on the flow surface 9. The second sensor 6 for detecting the static temperature is also integrated in the pipe 10, but is oriented in such a way that it does not directly face the flow in the filling direction. This means that no stagnation point is formed by the second sensor 6, but the gas can flow through unimpeded.

[0034] At least one of the two sensors 5, 6 can be attached to the tube 10 indirectly via the holding body 8. This applies in particular to the first sensor 5, since the holding body 8 allows the sensor 5 to be arranged as centrally as possible with respect to the filling path 3, so that the sensor 5 is better exposed to the flow. Depending on the design of the holding body 8, the second sensor 6 can also be integrated into the holding body. Figure 2 Some embodiments can be seen in a) to 2d). These figures show that the second sensor 6 is arranged downstream of the first sensor 5 in the flow direction of the gas, more precisely at an angle, in particular at a right angle, so that the gas can flow through unhindered. For flow optimization in the filling path 3, the retaining body 8 can have an outer contour that tapers in the filling direction, for example conically, upstream of the second sensor 6. If the flow direction of the gas in the filling path 3 is reversed, this outer contour of the retaining body 8 simultaneously ensures that the gas flows past the first sensor 5, so that the first sensor also only detects the static temperature.

[0035] The first sensor 5 is preferably integrated in the holding body 8 in such a way that the flow surface 9 of the sensor 5 simultaneously forms the flow surface 9 of the holding body 8. Figure 2 a) and 2b) are shown as flat surfaces. However, the flow surface 9 can also be designed as Figure 2 c) shaped convexly, or according to Figure 3 d) Concavely shaped. Flow optimization can also be achieved through the shape of the flow surface 9.

[0036] from Figure 3 In the figure, another holding body 8 with a sensor 5 for detecting the total temperature can be seen. The holding body 8 is integrated in the tube 10 and extends perpendicularly to the flow direction 15 of the gas. Figure 3 As shown, at the same time, the connection line 14 can be led to the sensor 5 via the holding body 8 to achieve the necessary electrical connection of the sensor 5. The second sensor 6 for detecting the static temperature is integrated into the inner side of the tube 10, so that the flow cross section is not restricted by the second sensor 6. Therefore, the gas flow flows past the second sensor 6. The connection line 14 of the second sensor 6 is led outward via the holding body 8.

[0037] Figure 4 Examples and Figure 3 The difference of the embodiment of is only that the second sensor 6 is integrated into the outer side of the tube 10, so that the static temperature of the gas in the storage volume 2 can be detected by means of the second sensor 6. In addition, the connection line 14 is also led out through the holding body 8.

Claims

1. A method for filling a storage volume (2) of a gas tank (1) with gas, in which method the gas is introduced into the storage volume (2) via a filling path (3) with an integrated tank valve (4), and the temperature of the gas in the region of a stagnation point (7) is detected by means of a sensor (5) integrated into the filling path (3), the stagnation point being formed by the sensor (5) and / or a holder (8) accommodating the sensor (5).

2. The method according to claim 1, characterized in that The measured value of the sensor (5) is compared with a predetermined temperature limit value and the filling process is stopped or interrupted if the temperature limit value is exceeded.

3. The method according to claim 1 or 2, characterized in that: The temperature of the gas outside the region of the blocking point (7), for example in the storage volume (2), is detected by means of a further sensor (6) and an average value and / or a difference is determined from the measured values ​​of the two sensors (5, 6).

4. The method according to claim 3, characterized in that The flow velocity of the gas is derived from the difference.

5. A gas tank (1) for a gas tank system, the gas tank having a storage volume (2) which can be filled with gas via a filling path (3) with an integrated tank valve (4), the gas tank also having a sensor (5) integrated into the filling path (3) for detecting the temperature of the gas, wherein: The sensor (5) and / or a holder (8) accommodating the sensor (5) form a blocking point (7) in the filling path (3), in the region of which the measuring region of the sensor (5) is arranged.

6. The gas tank (1) according to claim 5, characterized in that: The sensor (5) and / or the holding body (8) have a flow surface (9) which is oriented substantially perpendicularly to a flow direction (15) of the gas in the filling path (3) when the storage volume (2) is filled with gas.

7. The gas cylinder (1) according to claim 5 or 6, characterized in that: Outside the region of the blocking point (7), a further sensor (6) is integrated in the filling path (3) or in the storage volume (2).

8. The gas cylinder (1) according to any one of claims 5 to 7, characterized in that The filling path (3) is guided at least in sections via a pipe (10) which projects into the storage volume (2).

9. The gas cylinder (1) according to any one of claims 5 to 8, characterized in that The filling path (3), the tank valve (4) and the at least one sensor (5, 6) form a tank unit (11) which is inserted, in particular screwed, into a preferably centrally arranged end opening (13) of a wall (12) surrounding the storage volume (2).

10. A gas cylinder system comprising at least one gas cylinder (1) according to any one of claims 5 to 9.

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