Patent Description:
Fuel gas, such as hydrogen or natural gas, as a fuel source for electric vehicles is stored at high pressure. Tanks holding pressurized fuel gas onboard vehicles can be a safety hazard, especially at thermal runaway of an electric energy storage system of the vehicle. Thermal runaway of an electric energy storage system is a process where heat propagates through multiple cells of a battery pack, which process is accelerated by increased temperature, in turn releasing energy that further increases temperature. Thermal runaway occurs in situations where an increase in temperature changes the conditions in a way that causes a further increase in temperature, often leading to a destructive result. Following development of electrically driven vehicles, electric energy storage systems are increasingly part of vehicles' powertrain systems.

Fuel gas tanks are often equipped with temperature-pressure relief valves. These safety valves rupture if the temperature, and consequently the pressure in the tank, increases above a threshold value. The pressure release is very abrupt and uncontrolled. A fuel gas tank arrangement according to the preamble of claim1 is known from <CIT>.

According to a first aspect of the invention, there is provided a fuel gas tank arrangement in a vehicle. The fuel gas tank arrangement comprises a fuel gas tank for holding a pressurized fuel gas volume and a valve configured to ventilate fuel gas from the fuel gas tank into ambient surroundings. The valve comprises a controllable valve actuator communicatively connected to a control unit. The valve actuator is configured to open the valve to a determined opening degree for controlling a flow rate of ventilated fuel gas. The first aspect of the invention may seek to control ventilation of fuel gas from the fuel gas tank such that fuel gas is released in a controlled manner with regard to specifications of the fuel gas tank arrangement and a measured status of a fuel gas volume. A technical benefit may include that fuel gas is ventilated safely instead of being ventilated in an uncontrolled manner, which could increase the fire hazard. An additional benefit may be that fuel gas is ventilated only until the fire hazard is avoided such that fuel gas may be saved instead of being wasted. Fuel gas may be ventilated initially to a first extent, whereafter flow rate may be adjusted as the situation changes.

The fuel gas volume is to be understood as a (variable) amount of fuel gas contained in the fuel gas tank. The fuel gas volume may be in liquid form or gas form, or a combination thereof. Under normal operating conditions, the fuel gas volume is pressurized and/or cooled.

The control unit which communicates with/controls the valve actuator may be a tank control unit, an electric energy storage system control unit (e.g. a battery management unit), a vehicle control unit and/or an engine control unit, etc. The control unit may receive a signal indicating an imminent or occurring thermal runaway of the electric energy storage system. The signal may originate from a battery management unit. The signal may be directly received by the control unit or received through a vehicle control unit. Once the signal is received, the control unit may initiate opening of the valve that ventilates the fuel gas (hydrogen or other gaseous fuel) into the ambience outside the fuel gas tank. The position of the valve can be controlled to release the gas at a flow rate based on the required time of emptying, the initial state of the tank, and the characteristics of the tank.

In some examples, the fuel gas tank arrangement further comprises a sensor assembly configured to measure a status of the fuel gas volume. A technical benefit may include to collect data on a fuel gas pressure, a fuel gas temperature, a gas composition, a fuel gas mass, and/or ambient temperature of the fuel gas tank such that a ventilation flow rate may be controlled by adjusting the opening degree of the valve. The ambient temperature of the fuel gas tank is herein to be understood as the temperature of an environment in which the fuel gas tank is positioned.

According to a second aspect of the invention, there is provided a computer-implemented method for safety ventilation of fuel gas from a fuel gas tank arrangement into ambient surroundings. The fuel gas tank arrangement comprises a fuel gas tank comprising a pressurized fuel gas volume and a valve comprising a controllable valve actuator communicatively connected to a control unit. The valve actuator is configured to open and/or close the valve. The method comprises, by the control unit of a computer system, receiving data on an imminent or occurring thermal runaway of an electric energy storage system. The method further comprises controlling the valve actuator to open the valve to release an amount of fuel gas from the fuel gas tank. The second aspect of the invention may seek to, in a controlled manner, ventilate fuel gas from the fuel gas arrangement when there is an imminent or occurring thermal runaway in the electric energy storage system. As described in conjunction with the first aspect of the invention, a technical benefit may include that fuel gas is ventilated safely instead of being ventilated in an uncontrolled manner, which could increase the fire hazard. An additional benefit may be that fuel gas is ventilated only until the fire hazard is avoided such that fuel gas may be saved instead of being wasted. Fuel gas may be initially ventilated to a first extent, whereafter a flow rate may be adjusted as the situation changes.

In some examples, the method further comprises estimating a risk of ignition of the fuel gas volume based on the received data. A technical benefit may include controlling the release of fuel gas in accordance with the received data on the imminent or occurring thermal runaway. Release of fuel gas may increase if a temperature of the thermal runaway increases. Release of fuel gas may decrease if a temperature of the thermal runaway decreases, such as if the thermal runaway of the electric energy storage system has been contained. A basic aim of the method is to ventilate fuel gas as slowly as possible, both for saving fuel gas and because depressurized fuel gas may increase in temperature, which may increase the risk of ignition, especially if released quickly in large amounts.

In some examples, the method further comprises determining a target opening degree of the valve to control a flow rate of ventilated fuel gas based on the estimated risk of ignition. As mentioned hereinabove, the flow rate may be controlled, i.e. increased or decreased by opening the valve to a target opening degree, which is determined by the estimated risk of ignition of the fuel gas volume, which in turn is based on the received data. The data may be received from a control unit, such as an electric energy storage system control unit, e.g. a battery management unit and/or from a vehicle control unit, e.g. an engine control unit. As above, a technical benefit may include, that fuel gas is ventilated safely instead of being ventilated in an uncontrolled manner, which could increase the fire hazard. An additional benefit may be that fuel gas is ventilated only until the fire hazard is avoided such that fuel gas may be saved instead of being wasted. Fuel gas may be initially ventilated to a first extent, whereafter a flow rate may be adjusted as the situation changes.

In some examples, the target opening degree of the valve is further based on registered data on at least one of a valve dimension and/or a volume of the fuel gas tank. The registered data thus comprises stored information about certain properties of the fuel gas tank arrangement. The properties may indicate how much the valve may be opened and what flow rate is possible. The properties may also indicate how much fuel gas the fuel gas tank may contain and give an indication of how the target opening degree of the valve should be adjusted to correspond to the risk of ignition of the fuel gas volume.

In some examples, the risk of ignition is further based on a measured status of the fuel gas volume, the status comprising data on at least one of a fuel gas pressure, a fuel gas temperature, a gas composition, a fuel gas mass, and/or ambient temperature of the fuel gas tank. The measured status may thus be an updated, current status of the fuel gas volume, comprising measured data on the above parameters. By measuring the status, the risk of ignition of the fuel gas volume may be more accurately determined and the target opening degree of the valve may be adjusted accordingly.

In some examples, the risk of ignition is further based on registered data on characteristics of the fuel gas tank, which characteristics comprise data on at least one of a structure of the fuel gas tank comprising the fuel gas volume, a fuel gas tank material, presence of a temperature/pressure relief device, an orientation of the fuel gas tank, and/or a relative position of the fuel gas tank. The characteristics of the fuel gas tank may further determine the risk of ignition. The structure of the fuel gas tank may increase or decrease the risk of ignition and the material of the fuel gas tank may determine heat transfer to the fuel gas volume in the fuel gas tank. The fuel gas tank arrangement may also be provided with a temperature and pressure relief valve which would open at a predetermined pressure and/or temperature. To control the flow rate of ventilated fuel gas it is thus important to seek to keep the temperature and the pressure of the fuel gas volume below the predetermined temperature and pressure of the temperature and pressure relief valve. The temperature and pressure relief valve may be a last-resort solution to avoid a catastrophic explosion of the fuel gas tank. The orientation and relative position of the fuel gas tank may also determine the risk of ignition in that they affect the flow field of ventilated fuel gas such that the ventilated fuel gas may exit the fuel gas tank near, or in the direction of, the electric energy storage system in thermal runaway.

In some examples, the method further comprises closing the valve if the estimated risk of ignition is below a predetermined threshold value. Accordingly, if the thermal runaway has been contained, and/or the risk of ignition is low, fuel gas may be kept inside the fuel gas tank. However, if the estimated risk of ignition does not fall below the threshold value, ventilation continues until the fuel gas tank is substantially empty.

According to a third aspect of the invention, there is provided a control unit comprising a processor device configured to perform the method according to the second aspect of the invention. The control unit is mainly intended to receive data on any imminent or occurring thermal runaway and to control the valve actuator to open the valve to the determined opening degree, which depends on the risk of ignition of the fuel gas volume. The control unit may be a tank control unit comprised in the fuel gas tank arrangement. Alternatively, the control unit may be any other control unit of a vehicle comprising the fuel gas tank arrangement, where the control unit is communicatively connected to the valve actuator. The processor device of the control unit may estimate the risk of ignition according to any of the embodiments of the method of the invention.

According to a fourth aspect of the invention, there is provided a computer program product comprising program code for performing, when executed by the processor device of the third aspect of the invention, the method of any of the embodiments of the second aspect of the invention.

According to a fifth aspect of the invention, there is provided a control system comprising one or more control units configured to perform the method of any of the embodiments of the second aspect of the invention.

According to a sixth aspect of the invention, there is provided a non-transitory computer-readable storage medium comprising instructions, which when executed by the processor device of the fourth aspect of the invention, cause the processor device to perform the method of any of the embodiments of the second aspect of the invention.

According to seventh aspect of the invention, there is provided a vehicle comprising the fuel gas tank arrangement according to any of the embodiments of the first aspect of the invention and the control unit according to claim according to the third aspect of the invention.

In some examples, the vehicle further comprises an electric energy storage system and an electric energy storage system control unit communicatively connected with the fuel gas tank arrangement.

Additional features and advantages are disclosed in the following description, claims, and drawings, and in part will be readily apparent therefrom to those skilled in the art or recognized by practicing the invention as described herein.

With reference to the appended drawings, below follows a more detailed description of aspects of the invention cited as examples.

Aspects set forth below represent the necessary information to enable those skilled in the art to practice the invention.

The present invention provides a fuel gas tank arrangement and a method for ventilation of fuel gas from the fuel gas tank arrangement. Upon receipt of an indication of an imminent or occurring thermal runaway of an electric energy storage system, a valve actuator is controlled to open a valve and to release an amount of fuel gas from a fuel gas tank of the fuel gas tank arrangement. The present invention provides an improved arrangement and method in that flow rate of the ventilated fuel gas is controlled and may be adjusted depending on changing circumstances of the thermal runaway and conditions of the fuel gas tank arrangement.

<FIG> is an exemplary vehicle <NUM> according to one example of the invention. The vehicle comprises an electric energy storage system <NUM>, such as a battery, or battery pack. A fuel source of the vehicle <NUM> is fuel gas, e.g. hydrogen or natural gas. The vehicle <NUM> may be a fuel cell electric vehicle comprising one or more electric motors for propulsion of the vehicle or a hybrid vehicle comprising a combustion engine configured to use the fuel gas for combustion, and an electric motor for propulsion of the vehicle. For this purpose, the vehicle <NUM> comprises a fuel gas tank arrangement <NUM> and a control unit <NUM> configured to perform ventilation of fuel gas from the fuel gas tank arrangement <NUM>.

The control unit <NUM> may be a tank control unit, an electric energy storage system control unit (e.g. a battery management unit), a vehicle control unit and/or an engine control unit, etc. According to an aspect of the invention, there may also be provided a control system comprising one or more control units <NUM>. The control unit <NUM> may receive a signal indicating an imminent or occurring thermal runaway of the electric energy storage system <NUM>. The signal may originate from a battery management unit, such as a control unit of the electric energy storage system <NUM>. The signal may be directly received by the control unit <NUM> or received through a vehicle control unit. Once the signal is received, the control unit <NUM> may initiate opening of the valve <NUM> that ventilates the fuel gas (hydrogen or other gaseous fuel) into the ambience outside the fuel gas tank <NUM>. An opening position of the valve can be controlled to release the gas at a flow rate based on the required time of emptying the fuel gas tank <NUM>, a status of the fuel gas tank <NUM>, and/or the characteristics of the fuel gas tank <NUM>.

<FIG> illustrates the fuel gas tank arrangement <NUM>, which comprises a fuel gas tank <NUM> for holding a pressurized fuel gas volume, and a valve <NUM> configured to ventilate fuel gas from the fuel gas tank <NUM> into ambient surroundings of the fuel gas tank <NUM>. The valve <NUM> comprises a controllable valve actuator <NUM> communicatively connected to the control unit <NUM> comprised by the vehicle <NUM>. The control unit <NUM> is shown in dashed lines to illustrate that it is optionally comprised in the fuel gas tank arrangement <NUM>. The valve actuator <NUM> is configured to open the valve <NUM> to a determined opening degree for controlling a flow rate of ventilated fuel gas.

The fuel gas tank arrangement <NUM> may comprise a sensor assembly <NUM> configured to measure a status of the fuel gas volume contained in the fuel gas tank <NUM>. The sensor assembly <NUM> may be configured to collect measurable data on a fuel gas pressure, a fuel gas temperature, a fuel gas composition, a fuel gas mass, and/or ambient temperature of the fuel gas tank <NUM> such that a ventilation flow rate may be controlled by adjusting an opening degree of the valve <NUM> in accordance with the present status of the fuel gas volume. For instance, a high temperature and/or a high pressure of the fuel gas volume in the fuel gas tank <NUM> indicate that a risk of ignition is relatively high. Therefore, fuel gas should be ventilated before the thermal runaway is worsened. However, a temperature increase caused by depressurized fuel gas, and/or other factors such as flow field of the ventilated fuel gas may also need to be considered. The sensor assembly <NUM> may be communicatively connected to the control unit <NUM>. The control unit <NUM> is configured to collect data and use available information to determine a target opening degree of the valve <NUM>.

<FIG> shows a flowchart of a method <NUM> according to a second aspect of the invention. There is thus provided a computer-implemented method <NUM> for safety ventilation of fuel gas from a fuel gas tank arrangement <NUM> into ambient surroundings. The fuel gas tank arrangement <NUM> comprises a fuel gas tank <NUM> comprising a pressurized fuel gas volume and a valve <NUM> comprising a controllable valve actuator <NUM> communicatively connected to a control unit <NUM>, such as illustrated in <FIG>. The valve actuator <NUM> is configured to open and/or close the valve <NUM>. The method <NUM> comprises, by the control unit <NUM> of a computer system <NUM>:.

The method <NUM> allows, in a controlled manner, to ventilate fuel gas from the fuel gas tank arrangement <NUM> when there is an imminent or occurring thermal runaway in the electric energy storage system <NUM>. The electric energy storage system <NUM> is usually not comprised in the fuel gas tank arrangement <NUM>. However, the control unit <NUM> may be communicatively connected to a control unit of the electric energy storage system, such as a battery management unit <NUM>', or to a control unit of the vehicle <NUM>, such as an engine control unit <NUM>''. The control unit <NUM> directly controlling the valve actuator <NUM> may alternatively be the control unit of the electric energy storage system, such as the battery management unit <NUM>', or the control unit of the vehicle <NUM>, such as the engine control unit <NUM>''. As shown in <FIG>, the control unit <NUM> may thus be a part of a control system <NUM> comprising one or more control units <NUM>, <NUM>', <NUM>'' configured to perform the method <NUM>. The one or more control units <NUM>, <NUM>', <NUM>'' are communicatively connected to each other and configured to send, receive and/ process information and/or data to control and perform various functions.

The control unit <NUM> may comprise a processor device <NUM> (see <FIG>) configured to perform the method <NUM> of the second aspect of the invention. The control unit <NUM> of the fuel gas tank arrangement <NUM> is mainly intended to receive data on any imminent or occurring thermal runaway and to control the valve actuator <NUM> to open the valve <NUM> to a determined opening degree, which depends on the risk of ignition of the fuel gas volume. The processor device <NUM> of the control unit <NUM> may estimate the risk of ignition according to any of the embodiments of the second aspect of the invention.

Fuel gas may thereby be ventilated safely instead of being ventilated in an uncontrolled manner, which could increase the fire hazard. Additionally, fuel gas may be ventilated only until the fire hazard is avoided such that fuel gas may be saved instead of being wasted. Fuel gas may be initially ventilated to a first extent, whereafter a flow rate may be adjusted as the situation changes.

The method <NUM> may comprise an action S3 of estimating a risk of ignition of the fuel gas volume based on the received data on the imminent or occurring thermal runaway. Depending on the received data, the fuel gas may be released at different flow rates. Release of fuel gas may increase if a temperature of the thermal runaway increases, such as if the thermal runaway is worsening. Release of fuel gas may decrease if a temperature of the thermal runaway decreases, such as if the thermal runaway of the electric energy storage system <NUM> has been contained. Basically, an aim of the method <NUM> is to ventilate fuel gas as slowly as possible, both for saving fuel gas and because depressurized fuel gas may increase in temperature, which may further increase the risk of ignition, especially if released quickly in large amounts.

The method <NUM> may further comprise an action S4 of determining a target opening degree of the valve <NUM> to control a flow rate of ventilated fuel gas based on the estimated risk of ignition. The flow rate may thus be controlled, i.e. increased or decreased by opening the valve to a target opening degree, which is determined by the estimated risk of ignition of the fuel gas volume, which in turn is based on the received data. The data may be received from a control unit, such as an electric energy storage system control unit, e.g. a battery management unit and/or from a vehicle control unit, e.g. an engine control unit. As mentioned hereinbefore, fuel gas may be ventilated safely instead of being ventilated in an uncontrolled manner, which could increase the fire hazard. Further, fuel gas may be ventilated only until the fire hazard is avoided such that fuel gas may be saved instead of being wasted. Fuel gas may be initially ventilated to a first extent, whereafter a flow rate may be adjusted as the situation changes.

The target opening degree of the valve <NUM> may further be based on registered data on at least one of a valve dimension and/or a volume of the fuel gas tank <NUM>. The registered data may comprise stored information about certain properties of the fuel gas tank arrangement <NUM>. The properties may indicate how much the valve may be opened and what flow rate is physically possible. The properties may also indicate how much fuel gas the fuel gas tank <NUM> may contain and give an indication of how the target opening degree of the valve <NUM> should be adjusted to correspond to the risk of ignition of the fuel gas volume.

The risk of ignition may further be based on a measured status of the fuel gas volume. The status may comprise data on at least one of a fuel gas pressure, a fuel gas temperature, a gas composition, a fuel gas mass, and/or ambient temperature of the fuel gas tank <NUM>. The measured status may thus be an updated, current status of the fuel gas volume, comprising measured data on the above parameters. By measuring the status, the risk of ignition of the fuel gas volume may be more accurately determined and the target opening degree of the valve may be adjusted accordingly. The status may be measured continuously or intermittently during normal operation of the fuel gas tank arrangement and/or after receiving data on the imminent or occurring thermal runaway of the electric energy storage system <NUM>.

The risk of ignition may further be based on registered data on characteristics of the fuel gas tank <NUM>. The characteristics of the fuel tank <NUM> may comprise data on at least one of a structure of the fuel gas tank <NUM> comprising the fuel gas volume, a fuel gas tank material, presence of a temperature/pressure relief device, an orientation of the fuel gas tank <NUM>, and/or a relative position of the fuel gas tank <NUM>.

The structure of the fuel gas tank may increase or decrease the risk of ignition in that it may affect a heat transfer rate between a heat source outside the tank (i.e. ambient temperature) and the fuel gas volume inside the tank. The material of the fuel gas tank may also determine heat transfer to the fuel gas volume inside the fuel gas tank. The orientation and relative position of the fuel gas tank may also affect the risk of ignition in that they, to some extent, determine the flow field of ventilated fuel gas such that the ventilated fuel gas may exit the fuel gas tank near, or in the direction of, the electric energy storage system <NUM> during thermal runaway.

The fuel gas tank arrangement may optionally be provided with a temperature and pressure relief valve (not shown) which would open at a predetermined pressure and/or temperature. To control the flow rate of ventilated fuel gas via the valve <NUM> it is thus important to attempt to keep the temperature and the pressure of the fuel gas volume below the predetermined temperature and pressure of the temperature and pressure relief valve. The temperature and pressure relieve valve may be a last-resort solution to avoid a catastrophic explosion of the fuel gas tank.

The method <NUM> may further comprise an action of closing the valve <NUM> if the estimated risk of ignition is below a predetermined threshold value. Consequently, if the thermal runaway has been contained, and/or the risk of ignition is low, fuel gas may be kept inside the fuel gas tank <NUM>. However, if the estimated risk of ignition does not fall below the threshold value, ventilation continues at a higher or lower flow rate until the fuel gas tank <NUM> is substantially empty.

<FIG> is a schematic diagram of a computer system <NUM> for implementing examples disclosed herein. The computer system <NUM> is adapted to execute instructions from a computer-readable medium to perform these and/or any of the functions or processing described herein. The computer system <NUM> may be connected (e.g., networked) to other machines in a LAN, an intranet, an extranet, or the Internet. While only a single device is illustrated, the computer system <NUM> may include any collection of devices that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. Accordingly, any reference in the disclosure and/or claims to a computer system, computing system, computer device, computing device, control system, control unit, electronic control unit (ECU), processor device, etc., includes reference to one or more such devices to individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. For example, control system may include a single control unit or a plurality of control units connected or otherwise communicatively coupled to each other, such that any performed function may be distributed between the control units as desired. Further, such devices may communicate with each other or other devices by various system architectures, such as directly or via a Controller Area Network (CAN) bus, etc..

The computer system <NUM> may comprise at least one computing device or electronic device capable of including firmware, hardware, and/or executing software instructions to implement the functionality described herein. The computer system <NUM> may include a processor device <NUM> (may also be referred to as a control unit), a memory <NUM>, and a system bus <NUM>. The computer system <NUM> may include at least one computing device having the processor device <NUM>. The system bus <NUM> provides an interface for system components including, but not limited to, the memory <NUM> and the processor device <NUM>. The processor device <NUM> may include any number of hardware components for conducting data or signal processing or for executing computer code stored in memory <NUM>. The processor device <NUM> (e.g., control unit) may, for example, include a general-purpose processor, an application specific processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a circuit containing processing components, a group of distributed processing components, a group of distributed computers configured for processing, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The processor device may further include computer executable code that controls operation of the programmable device.

The system bus <NUM> may be any of several types of bus structures that may further interconnect to a memory bus (with or without a memory controller), a peripheral bus, and/or a local bus using any of a variety of bus architectures. The memory <NUM> may be one or more devices for storing data and/or computer code for completing or facilitating methods described herein. The memory <NUM> may include database components, object code components, script components, or other types of information structure for supporting the various activities herein. Any distributed or local memory device may be utilized with the systems and methods of this description. The memory <NUM> may be communicably connected to the processor device <NUM> (e.g., via a circuit or any other wired, wireless, or network connection) and may include computer code for executing one or more processes described herein. The memory <NUM> may include non-volatile memory <NUM> (e.g., read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.), and volatile memory <NUM> (e.g., random-access memory (RAM)), or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a computer or other machine with a processor device <NUM>. A basic input/output system (BIOS) <NUM> may be stored in the non-volatile memory <NUM> and can include the basic routines that help to transfer information between elements within the computer system <NUM>.

A number of modules can be implemented as software and/or hard-coded in circuitry to implement the functionality described herein in whole or in part. The modules may be stored in the storage device <NUM> and/or in the volatile memory <NUM>, which may include an operating system <NUM> and/or one or more program modules <NUM>. All or a portion of the examples disclosed herein may be implemented as a computer program product <NUM> stored on a transitory or non-transitory computer-usable or computer-readable storage medium (e.g., single medium or multiple media), such as the storage device <NUM>, which includes complex programming instructions (e.g., complex computer-readable program code) to cause the processor device <NUM> to carry out the steps described herein. Thus, the computer-readable program code can comprise software instructions for implementing the functionality of the examples described herein when executed by the processor device <NUM>. The processor device <NUM> may serve as a controller or control system for the computer system <NUM> that is to implement the functionality described herein.

The computer system <NUM> also may include an input device interface <NUM> (e.g., input device interface and/or output device interface). The input device interface <NUM> may be configured to receive input and selections to be communicated to the computer system <NUM> when executing instructions, such as from a keyboard, mouse, touch-sensitive surface, etc. Such input devices may be connected to the processor device <NUM> through the input device interface <NUM> coupled to the system bus <NUM> but can be connected through other interfaces such as a parallel port, an Institute of Electrical and Electronic Engineers (IEEE) <NUM> serial port, a Universal Serial Bus (USB) port, an IR interface, and the like. The computer system <NUM> may include an output device interface <NUM> configured to forward output, such as to a display, a video display unit (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)). The computer system <NUM> may also include a communications interface <NUM> suitable for communicating with a network as appropriate or desired.

The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the invention.

Claim 1:
A fuel gas tank arrangement (<NUM>) in a vehicle (<NUM>), the fuel gas tank arrangement (<NUM>) comprising:
- a fuel gas tank (<NUM>) for holding a pressurized fuel gas volume, and
- a valve (<NUM>) configured to ventilate fuel gas from the fuel gas tank (<NUM>) into ambient surroundings,
characterized in that
the valve (<NUM>) comprises a controllable valve actuator (<NUM>) communicatively connected to a control unit (<NUM>), the valve actuator (<NUM>) being configured to open the valve (<NUM>) to a determined opening degree for controlling a flow rate of ventilated fuel gas.