Gas tank and gas tank system

Abstract

The invention relates to a gas tank (1) for a gas tank system, having a storage volume (3) surrounded by a wall (2), which storage volume can be filled with gas via a tank line (4) having an integrated tank valve (5), and having a temperature sensor (6) for detecting a temperature in the gas tank (1), the temperature sensor (6) is arranged outside the storage volume (3) and is thermally attached to the storage volume (3) via a heat conductor (7) protruding into the storage volume (3). The invention also relates 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 gas tank for storing gas, such as hydrogen or natural gas, and is particularly used in vehicles that run on gas, such as fuel cell vehicles or gas vehicles.

[0002] Furthermore, the invention relates to a gas cylinder system having at least one gas cylinder according to the invention. Background Art

[0003] In vehicles running on natural gas, such as hydrogen, the gas is typically stored under pressure in gas tanks. In the case of hydrogen, the pressure can reach as high as 70 MPa. The temperature in the gas tank can rise to as high as 85°C. This temperature limit is typically dictated by the material of the gas tank, with carbon fiber-reinforced plastic (CFRP) often used. When using CFRP, the plastic, especially the synthetic resin, required to secure the carbon fibers becomes too soft above 85°C and no longer provides the required strength for the gas tank.

[0004] For example, since hydrogen has a negative Joule-Thomson effect in the relevant temperature range, it heats up when filling the gas or hydrogen tank. Therefore, to avoid damage to the gas tank, the hydrogen is cooled to approximately -40°C before the filling process. Furthermore, an upwardly angled tank nozzle can be used to fill the gas tank, which promotes mixing of fresh hydrogen with the tank contents, thereby reducing heating. As a further measure, the tank temperature can be measured or monitored so that the filling process can be interrupted if a temperature limit is exceeded. To reliably adhere to the temperature limit, the interruption must be performed early. Consequently, high measurement tolerances have a negative impact. Since the mass stored in the gas tank is usually also determined based on the tank temperature, high measurement tolerances can further lead to incorrectly calculated tank levels or incorrectly calculated remaining range.

[0005] Therefore, for both purposes, it is desirable to obtain the most accurate possible information about the temperature in the gas tank. However, to comply with temperature limits, the locally occurring maximum temperature is crucial, while the average temperature is more appropriate for calculating the stored mass. These two desires are difficult to reconcile. This is particularly true because the thermal elements, thermistors, or temperature resistors typically used for temperature measurement are only capable of detecting the temperature of their immediate surroundings. The restricted accessibility of the tank interior also severely limits the choice of sensor location.

[0006] For example, US 2010 / 0032934 A1 discloses a gas tank having a tank line and a tank valve for filling the tank with gas, as well as a sensor arranged on the tank line for detecting a gas state variable. The sensor is positioned so that it is outside the pressure jet formed when the gas tank is filled with gas. This improves the sensor's measurement accuracy. Summary of the Invention

[0007] The object of the present invention is to provide a gas tank having a temperature sensor for detecting the temperature in the gas tank, which temperature sensor has high measurement accuracy and is easy to assemble.

[0008] To achieve this object, a gas cylinder having the features of claim 1 is proposed. Advantageous developments of the invention are revealed in the dependent claims. Furthermore, a gas cylinder system having at least one gas cylinder according to the invention is proposed.

[0009] A gas tank for a gas tank system is proposed. The gas tank has a storage volume enclosed by a wall, the storage volume being fillable with gas via a tank line having an integrated tank valve, and a temperature sensor for detecting the temperature in the gas tank. The temperature sensor is arranged outside the storage volume and is thermally attached to the storage volume via a heat conductor extending into the storage volume.

[0010] The heat conductor transmits temperature information from the interior of the gas tank to the temperature sensor. This allows the temperature sensor to detect the temperature of the gas in the gas tank, even though the sensor is located outside the storage volume. Furthermore, the placement of the temperature sensor outside the storage volume simplifies its assembly and, if necessary, its removal in the event of a malfunction, as it is more accessible. Similarly, the necessary electrical connections for the temperature sensor are simplified.

[0011] Since the temperature sensor in the proposed arrangement does not come into contact with the gas, it is optimally protected. Furthermore, a gas-tight design of the temperature sensor can be dispensed with. Consequently, a simple and cost-effective temperature sensor can be installed.

[0012] The section of the heat conductor protruding into the storage volume preferably has an axial length L measured parallel to the gas tank's longitudinal axis A. Over this length L, an average value can be determined of the measured values ​​which corresponds to or at least approximates the average temperature in the gas tank.

[0013] The heat conductor is also preferably oriented parallel to the longitudinal axis A. This means that the heat conductor extends into the storage volume in the axial direction, so that the temperature can be detected up to the depth of the storage volume. For example, the heat conductor can be a rod made of a material with particularly good heat conductivity.

[0014] In a further development of the invention, it is proposed that the tank line terminate in a tube that extends into the storage volume and forms an outflow opening for the gas. Through this tube, the gas can be introduced more centrally, thereby achieving better mixing. For this purpose, the tube is preferably constructed in the manner of a tank nozzle. A defined gas jet can also be formed via the outflow opening of the tube. In particular, the tube can extend parallel to the heat conductor. Furthermore, the tube can have essentially the same length as the heat conductor, so that the heat conductor reaches approximately as far as the gas jet. In this way, temperature information is also transmitted via the heat conductor to the temperature sensor, which makes it possible to detect the maximum temperature occurring locally when the gas tank is filled with gas.

[0015] Advantageously, the tank line, tank valve, temperature sensor, and heat conductor form a tank unit, which is inserted into a preferably centrally located end opening in the wall of the gas tank. The tank unit simplifies assembly because the tank line, tank valve, temperature sensor, and heat conductor can be inserted into the wall opening as a preassembled unit. If the tank line is formed at least in sections by a tube, this tube can also be part of the preassembled unit.

[0016] The tank unit is preferably placed in the opening of the wall so that the opening is closed gas-tightly. Alternatively or additionally, at least one sealing element, such as a sealing ring, can be placed between the tank unit and the wall of the gas tank.

[0017] Preferably, the tank unit accommodates at least one further component, for example, a further valve for removing gas from the gas tank. The further valve can in particular be an electromagnetically actuated valve which is designed to close in the absence of current in order to prevent gas from escaping from the gas tank in the event of a fault.

[0018] Furthermore, the tank unit preferably has a section protruding from the outside of the wall, into which the temperature sensor is integrated. This allows the temperature sensor to be located not only outside the storage volume but also outside the wall, further optimizing accessibility to the sensor. Furthermore, this simplifies the necessary electrical connections for the temperature sensor.

[0019] Furthermore, the tank unit preferably includes a section with an external thread, via which the tank unit is screwed into the opening in the wall. This creates a positive fit between the tank unit of the gas tank and the wall, thereby securing the position of the tank valve. To this end, the opening in the wall preferably has an internal thread that corresponds to the external thread of the tank unit.

[0020] Furthermore, it is proposed that the wall of the gas tank is circular in cross section. The circular cross section increases the load-bearing capacity of the gas tank, thereby enabling high storage pressures. The circular shape also promotes a uniform pressure and temperature distribution in the gas tank.

[0021] Alternatively or additionally, it is proposed that the wall of the gas tank is spherically shaped in at least one end section. The spherical shape of at least one end section further increases the compressive strength of the gas tank.

[0022] Furthermore, a gas tank system is proposed, comprising at least one gas tank according to the present invention. For example, multiple gas tanks of the same type can be held in a parallel arrangement on a common frame. This frame facilitates the installation of the gas tank system into a vehicle, such as a fuel cell vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Hereinafter, preferred embodiments of the present invention are explained in more detail with reference to the accompanying drawings.

[0024] Figure 1 A schematic longitudinal section through a gas tank according to the invention is shown in the region of a tank unit with an integrated temperature sensor. DETAILED DESCRIPTION

[0025] The illustrated gas cylinder 1 comprises a wall 2 with a perfectly circular cross-section, which encloses a storage volume 3 for gas. The illustrated end section 15 of the wall 2 is spherically shaped and has a central opening 11, into which a tank unit 10 is inserted or screwed. The tank unit 10 has a tank line 4, into which a tank valve 5 is integrated. This valve allows the gas cylinder 1 to be filled with gas via the tank line 4 while simultaneously preventing the gas from escaping from the gas cylinder 1. The tank line 4 extends via a tube 8 extending into the storage volume 3. At its end, the tube forms an outflow opening 9 for the gas. A defined gas jet 17 can be formed via the outflow opening 9.

[0026] The tank unit 10 inserted into the opening 11 also has a temperature sensor 6, which is integrated in a section 12 of the tank unit 10 that protrudes beyond the wall 2 of the gas tank 1, making the temperature sensor 6 easily accessible. Furthermore, the necessary electrical connections can be easily made via the connecting line 16.

[0027] The temperature sensor 6, integrated into the section 12 of the tank unit 10, is therefore arranged outside the storage volume 3 of the gas tank 1 and is thus optimally protected from the influence of the gas. To detect the temperature in the gas tank 1, the temperature sensor 6 is thermally attached to the storage volume 3 via a heat conductor 7, which extends over a length L into the storage volume 3 of the gas tank 1. The axial length L is measured parallel to the longitudinal axis A of the gas tank 1.

[0028] The length L of the heat conductor 7 is selected so that an average value is formed from the different temperature information and transmitted to the temperature sensor 6. To this end, the heat conductor 7 is made of a material with particularly good thermal conductivity. The temperature information transmitted to the temperature sensor 6 corresponds to the average temperature in the gas cylinder 1 or is at least very close to this average temperature.

[0029] like Figure 1 As shown by way of example in FIG, the tank unit 10 can include a section 13 with an external thread 14, by which the tank unit 10 is screwed into the opening 11 of the wall 2. In this way, a form-locking connection is achieved between the tank unit 10 and the wall 2, which serves to fix the position of the tank unit 10.

Claims

1. A gas tank (1) for a gas tank system, the gas tank having a storage volume (3) enclosed by a wall (2), the storage volume being able to be filled with gas via a tank line (4) having an integrated tank valve (5), and having a temperature sensor (6) for detecting the temperature in the gas tank (1), wherein: The temperature sensor (6) is arranged outside the storage volume (3) and is thermally attached to the storage volume (3) via a heat conductor (7) which projects into the storage volume (3).

2. The gas tank (1) according to claim 1, characterized in that: The section of the heat conductor (7) that projects into the storage volume (3) has an axial length (L) measured parallel to the longitudinal axis (A) of the gas tank (1), wherein the heat conductor (7) is preferably oriented parallel to the longitudinal axis (A).

3. The gas tank (1) according to claim 1 or 2, characterized in that: The tank line (4) ends in a pipe (8) which projects into the storage volume (3) and forms an outflow opening (9) for the fuel gas, wherein the pipe (8) preferably extends parallel to the heat conductor (7).

4. The gas cylinder (1) according to any one of the preceding claims, characterized in that The tank line (4), the tank valve (5), the temperature sensor (6) and the heat conductor (7) form a tank unit (10), which is inserted into an end opening (11) of the wall (2), wherein the end opening is preferably arranged centrally.

5. The gas tank (1) according to claim 4, characterized in that: The tank unit (10) has a section (12) protruding from the outside of the wall (2), and the temperature sensor (6) is integrated into the section protruding from the outside of the wall.

6. The gas cylinder (1) according to claim 4 or 5, characterized in that: The tank unit (10) comprises a section (13) having an external thread (14), via which the tank unit (10) is screwed into an opening (11) of the wall (2).

7. The gas cylinder (1) according to any one of the preceding claims, characterized in that The wall (2) is circular in cross section and / or spherically shaped in at least one end section (15).

8. A gas cylinder system comprising at least one gas cylinder (1) according to one of the preceding claims.

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