DE102019132504A1 - Gas pressure sensor and gas supply arrangement - Google Patents

Abstract

The technology disclosed here relates to a gas pressure sensor 10 with a connection opening 22, a membrane 30, a channel 20 and a sensor element 40, at least one delay element 60, 70 being arranged in the channel 20 in order to spread pressure in the channel 20 and / or to increase the temperature delay in channel 20. This can prevent an output signal from overshooting when the pressure increases rapidly. According to the invention, the technology disclosed here also relates to a gas supply arrangement 100 with such a gas pressure sensor 10.

Description

The technology disclosed here relates to a gas pressure sensor and a gas supply arrangement.

Motor vehicles can be operated with gaseous fuel, for example. For this purpose, compressed gas storage systems can be installed in the motor vehicle, which can have, for example, one or more pressure vessels for storing gaseous fuel, switchable tank valves and gas pressure sensors. The gas pressure sensors are used to monitor the gas pressure at certain points.

It is basically known to provide gas pressure sensors with temperature compensation which compensates for influences due to changing ambient temperature. However, it was recognized that gas pressure sensors can briefly indicate pressures which are too high, especially when the tank valves are switched on. This phenomenon cannot be remedied with conventional temperature compensation devices.

It is a preferred object of the technology disclosed here to reduce or eliminate at least one disadvantage of a previously known solution or to propose an alternative solution. In particular, it is a preferred object of the technology disclosed here to provide a gas pressure sensor with improved behavior when tank valves are switched on. Further preferred objects can result from the advantageous effects of the technology disclosed here. The objects are achieved by the subject matter of the independent claims. The dependent claims represent preferred configurations.

The technology disclosed here relates to a gas pressure sensor. The gas pressure sensor has a connection opening. It has a membrane which deforms depending on a gas pressure. The gas pressure sensor has a channel which leads from the connection opening to the membrane. It also has a sensor element for detecting the deformation of the membrane and for generating a signal based thereon.

The gas pressure sensor has at least one delay element which is arranged in the channel and delays a pressure spread in the channel and / or a temperature increase in the channel.

Such a gas pressure sensor can prevent the gas pressure sensor from briefly displaying too high a pressure when tank valves are switched on, ie when the gas pressure increases very quickly. A corresponding behavior was observed with gas pressure sensors known from the prior art. For example, with such gas pressure sensors known from the prior art, a gas pressure can be briefly displayed which is more than 100 bar above the gas pressure that is actually present or is possible at all due to the pressure conditions in the system. This can lead to undesirable effects such as the activation of safety devices. An exemplary signal curve is in 1 which is described below.

It was recognized that such short-term increases in the indicated pressure cannot be based on an impulse force during the pressure increase.

• Der Durchmesser der Drucksensormembran beträgt: d = 3 mm
• Die Fläche der Drucksensormembran beträgt: A = d²/4*Pi = 7,07E-6 m²

$$\text{Kraft }@20\text{ bar}:\text{F}=\text{p}*A=2\text{E}6\text{ Pa}*7.07\text{E}-6{\text{ m}}^2=\mathrm{14,14}\text{N}$$

$$\text{Kraft }@\text{ 76}0\text{ bar}:\text{F}=\text{p}*A=76\text{E}6\text{ Pa}*\mathrm{7,07}\text{E}-6{\text{ m}}^2=537.32\text{N}$$

• Kraftunterschied: 523 N
• Angenommenes Volumen einer Hochdruck-Entnahme-Leitung: 15 ml H₂-Masse bei 20 bar: 25 mg
• H₂-Masse bei 760 bar: 637 mg
• Innerhalb von 100 ms strömen also 617 mg H₂ in die Leitung.
• Der mittlere Massenstrom beträgt 6,17 g/s = 22,2 kg/h.

For this purpose, the following calculation was made as an example, which indicates a proportion of the impulse force in a force difference on a pressure sensor membrane with a diameter of 3 mm:

• The diameter of the pressure sensor membrane is: d = 3 mm
• The area of the pressure sensor ^{membrane is: A = d 2/4} * Pi = 7.07E-6 m ²

$$\text{force}@\mathrm{20th}\text{bar}:\text{F.}=\text{p}*\mathrm{A.}=2\text{E.}\mathrm{6th}\text{Pa}*7.07\text{E.}-\mathrm{6th}{\text{m}}^2=14.14\text{N}$$

$$\text{force}@\text{76}0\text{bar}:\text{F.}=\text{p}*\mathrm{A.}=76\text{E.}\mathrm{6th}\text{Pa}*7.07\text{E.}-\mathrm{6th}{\text{m}}^2=537.32\text{N}$$

• Difference in force: 523 N
• Assumed volume of a high pressure withdrawal line: 15 ml H ₂ mass at 20 bar: 25 mg
• H ₂ mass at 760 bar: 637 mg
• So within 100 ms 617 mg H ₂ flow into the line.
• The mean mass flow is 6.17 g / s = 22.2 kg / h.

$$\begin{array}{l}\text{Kraft}:\text{F}=\text{Dp}/\text{Dt}=\mathrm{12,3}\text{E}-3\text{ kg}*\text{m}/{\text{s}}^2/\mathrm{0,1}=123\text{E}-3\text{ kg}*\text{m}/{\text{s}}^2=123\text{E}-3\text{ N}=\\ \mathrm{0,123}\text{ N}\end{array}$$

The flow velocity at 6.2 g / s in a D3 line is 20.5 m / s. $$\text{pulse}:\text{p}=\text{m}*\text{v}=0.6\text{E.}-\mathrm{3rd}\text{kg}*20.5\text{m}/\text{s}=12.3\text{E.}-\mathrm{3rd}\text{kg}*\text{m}/\text{s}$$

$$\begin{array}{l}\text{force}:\text{F.}=\text{Dp}/\text{German}=12.3\text{E.}-\mathrm{3rd}\text{kg}*\text{m}/{\text{s}}^2/0.1=123\text{E.}-\mathrm{3rd}\text{kg}*\text{m}/{\text{s}}^2=123\text{E.}-\mathrm{3rd}\text{N}=\\ 0.123\text{N}\end{array}$$

• Der Impuls macht ca. 0,2 Promille aus.

This gives the proportion of the momentum force in the force difference:

• The impulse amounts to approx. 0.2 per mille.

Due to the very small proportion of the impulse force, the pressure increase mentioned above cannot come from the impulse.

Rather, it has been found that the brief display of an excessively high pressure value is based on gas compression immediately in front of the membrane and a temperature increase caused by it, which changes the mobility of the membrane and cannot be compensated in time by normal temperature compensation measures. The delay element in the channel provided in accordance with the technology disclosed here can slow down the spread of pressure in the channel so that there is no sufficiently high compression in front of the membrane to trigger a relevant temperature increase and / or an otherwise fully occurring temperature increase in the channel, which is triggered by a compression that has already taken place, can be delayed or removed.

The connection opening can in particular be an opening of the gas pressure sensor with which the gas pressure sensor can be connected to a volume whose gas pressure is to be measured. For example, it can be a withdrawal line which leads from a pressure vessel to a consumer.

The membrane can in particular be arranged at the end of the channel which is opposite the connection opening. By means of the channel it can be achieved that in principle the same pressure is applied to the membrane as to the connection opening, which relates in particular to a state after a pressure equalization to be carried out. The delay element provided enables a pressure increase on the membrane to be slowed down in comparison to the connection opening, as a result of which the advantageous effects already described can be achieved. The channel can be straight, but it can also be curved. It can in particular have a constant diameter outside of the delay element or the delay elements. The signal that is generated by the sensor element based on the deformation of the membrane can in particular be an analog or other output signal that is evaluated by an evaluation circuit. Such an evaluation circuit can, for example, output a value which indicates the gas pressure on the membrane and thus, as a rule, also on the connection opening.

According to one embodiment, a delay element is designed as a taper compared to the adjacent part of the channel. As a result, the propagation of a pressure wave towards the membrane can be slowed down so that a pressure build-up in front of the membrane takes place more slowly than usual. The taper can, for example, be designed as a diameter reduction of the channel. For example, the diameter can be reduced by more than 50%, more than 80%, more than 90% or more than 95% compared to the adjacent part of the channel or also to the rest of the channel.

According to one embodiment, at least one delay element is designed as a heat dissipation element. As a result, any compression that may occur cannot increase the temperature as far or as quickly as it could without a heat dissipating element. A heat dissipation element can in particular be a device which engages in the channel and which has a high thermal conductivity and, for example, with an external heat sink can be connected to dissipate the heat. For example, a filter or, in particular, a sintered filter can be used as the heat dissipation element. A filter can, for example, have pores of a defined size, which ensure a defined passage of gas, with such pores being formed in a thermally conductive material which engages in the channel and can thus dissipate any heat that is generated.

According to one embodiment, the gas pressure sensor has exactly one delay element. This allows a simple implementation. For example, the delay element can be an already mentioned taper or an already mentioned heat dissipation element. The latter can in particular be designed as a filter or as a sintered filter.

According to one embodiment, the gas pressure sensor has a first delay element and a second delay element. The first delay element can in particular be designed as a taper compared to the adjacent part of the channel. The second delay element can be designed as a heat dissipation element. The taper or the heat dissipation element can in particular be designed as already described. By using two delay elements, their effect can be combined, so that the formation of an undesired signal increase in the event of a sudden pressure increase can be prevented in a particularly advantageous manner.

According to one embodiment, the gas pressure sensor has a pressure port and a connector housing. The connection opening, the channel and the membrane can in particular be arranged in the pressure port. The sensor element can in particular be arranged in the connector housing. The pressure port and connector housing can in particular be connected to one another. For example, they can be clipped onto one another. This allows the pressure nozzle and connector housing to be manufactured independently, as well as simple maintenance of the components contained therein.

The delay element or a component containing the delay element can in particular have an external thread and be screwed into a complementary internal thread of the channel. This allows simple assembly of the delay element.

A taper can also be formed, for example, by means of a material projection formed in one piece with the rest of the material surrounding the channel or connected in some other way.

The gas pressure sensor can in particular have an element welded to the rest of the gas pressure sensor, in which the or a delay element is arranged. This allows an element with the delay element to be produced separately, which element can then be attached to the rest of the gas pressure sensor by simply welding it on. Other fastening variants such as gluing or clamping can also be used here.

The delay element can in particular have a length of 10% to 30% of a length of the channel. Such designs have proven to be advantageous both for a taper and for a heat dissipation element.

If the gas pressure sensor has both a taper and a heat dissipation element, the heat dissipation element can in particular be arranged closer to the membrane than the taper. This allows a more targeted dissipation of heat generated in front of the membrane and a timely prevention of a sudden increase in pressure.

The gas pressure sensor can in particular be designed to measure a gas pressure of hydrogen, but also of other gases.

The technology disclosed here also relates to a gas supply arrangement. The gas supply arrangement has a pressure vessel for storing gas. It has a withdrawal line which is connected to the pressure vessel. The gas supply arrangement has a valve for switching or controlling a gas flow, the valve being arranged in the extraction line or between the extraction line and the pressure vessel. The gas supply arrangement has a gas pressure sensor as described herein, the connection opening of which is connected to the extraction line, the valve being located between the gas pressure sensor and the pressure vessel.

With regard to the gas pressure sensor, all of the designs and variants described herein can be used.

A gas pressure in the extraction line can be monitored by means of such a gas supply arrangement without the negative effects of a significantly increased pressure value described at the outset occurring when valves are switched on. The extraction line can in particular lead to a consumer such as an internal combustion engine or a fuel cell, which is operated with gas stored in the pressure vessel, that is to say in this case with gaseous fuel.

The gas supply arrangement can in particular be used in a motor vehicle such as a passenger car, a motorcycle or a utility vehicle. The pressure vessel is used in particular to store fuel that is gaseous under ambient conditions. The gas supply arrangement can be used, for example, in a motor vehicle that is operated with compressed (also called “Compressed Natural Gas” or CNG) or liquefied (also called “Liquid Natural Gas” or LNG) natural gas or with hydrogen. The connecting line can be fluidly connected to at least one energy converter which is set up to convert the chemical energy of the fuel into other forms of energy. The pressure vessel can in particular be a composite overwrapped pressure vessel. For example, it can be a cryogenic pressure vessel or a high pressure gas vessel. High-pressure gas containers are designed to store fuel permanently at ambient temperatures at a nominal operating pressure (also called “nominal working pressure” or NWP) of approx. 350 barg (= overpressure compared to atmospheric pressure), further preferably of approx. 700 barg or more. A cryogenic pressure vessel is suitable for storing the fuel at the aforementioned operating pressures even at temperatures which are well below the operating temperature of the motor vehicle.

The valve can in particular be a tank shut-off valve. This can also be referred to as a shut-off valve. The tank shut-off valve is, for example, the valve whose inlet pressure (at least essentially) corresponds to the container pressure. The tank shut-off valve is in particular a controllable or regulatable and, in particular, normally closed valve. The tank shut-off valve is usually integrated in an on-tank valve. The on-tank valve is mounted directly on one end of the pressure vessel and a valve unit that is directly fluidly connected to the interior of the pressure vessel. In Regulation (EU) No. 406/2010 of the Commission of April 26, 2010 for the implementation of Regulation (EC) No. 29/2009 of the European Parliament and the Council on the type approval of hydrogen-powered motor vehicles, such a tank shut-off valve is also referred to as the first valve.

A pressure vessel can in particular have a liner and / or a wall.

In other words, it has been recognized that switching on valves in connected lines can lead to very rapid pressure increases, whereby a sudden pressure increase in a dead end in front of a membrane can generate compression energy, which is converted into heat and heats the gas. As a result of heat transfer, this also leads to an increase in temperature in the surrounding metal, especially at the usually thinnest point, the measuring membrane. This reduces their rigidity, which results in increased deformation. The expansion of a strain gauge applied to the membrane is increased and a sensor thereby determines a higher pressure for a certain period of time, which is not physically present.

Such a measurement deviation can be, for example, over 10% of the measuring range and thus lead to problems for functions of the system, since, for example, safety functions can be triggered incorrectly. The temperature compensation used in known designs is typically too sluggish to compensate for this effect. This is designed to compensate for temperature changes of the entire component, not the selective and very rapid heating of the measuring membrane.

To solve the problem, for example, a hole can be strongly tapered towards the open side, for example by installing a cover.

Due to the pressure loss in the tapered area, the pressure gradient in the bore cavity is significantly lower. This significantly reduces the pressure increase and thus the heating effect and the measurement is less falsified.

For example, an internal thread can be cut into the bore or into the channel and a grub screw with a narrow bore can be installed. A cover can also be welded on or a cover with an external thread can be welded on.

A material with good thermal conductivity can also be used in the bore or in the channel in such a way that the bore remains sufficiently gas-permeable to enable a measurement. A large part of the heat generated can then be conducted away from the measuring membrane and into other areas of the component. Therefore, the effect of heating the measuring membrane is significantly reduced and the measurement is less falsified.

In order to enable good heat transfer between the gas and the material or heat dissipation element used, it is advantageous if the structure of the material or heat dissipation element used has the largest possible surface area. For example, a fabric or a honeycomb can be used. An insert made of sintered filter material has proven to be particularly suitable. The ratio “length filter” / “length channel in sensor” can be between 0.1 and 0.3, for example. Such values have proven to be advantageous.

• 1: einen Druckverlauf bei Gasdrucksensoren gemäß dem Stand der Technik,
• 2: einen Gasdrucksensor gemäß einem ersten Ausführungsbeispiel,
• 3: einen Gasdrucksensor gemäß einem zweiten Ausführungsbeispiel,
• 4: einen Gasdrucksensor gemäß einem dritten Ausführungsbeispiel, und
• 5: eine Gasversorgungsanordnung.

The technology disclosed here will now be explained with reference to the figures. Show it:

• 1 : a pressure curve for gas pressure sensors according to the state of the art,
• 2 : a gas pressure sensor according to a first embodiment,
• 3rd : a gas pressure sensor according to a second embodiment,
• 4th : a gas pressure sensor according to a third embodiment, and
• 5 : a gas supply arrangement.

1 shows schematically a typical profile of a pressure signal from a gas pressure sensor according to the prior art when tank valves are switched on. The actual pressure increases very quickly from a very low pressure, which can for example correspond to an ambient pressure, to a pressure which essentially corresponds to the internal pressure of a pressure vessel in which gaseous fuel or other gas is stored. In 1 time t is shown in arbitrary units on the horizontal axis and a signal S is shown on the vertical axis.

As shown, the pressure initially remains at a very low value, ie before a valve is opened. When a valve is opened, the signal S increases suddenly, but then drops again approximately exponentially to a value which then no longer changes. The latter value essentially corresponds to the internal pressure of a pressure vessel minus a mostly only slight reduction in pressure due to the opening of the valve. The highest value reached, however, is a value P higher, so it represents a peak. However, this does not correspond to an actually existing pressure, but is caused by a temperature increase immediately in front of a measuring membrane, the temperature increase increasing the flexibility of the measuring membrane and thus their deformation also increases. This deformation is converted into the signal S and thus leads to the in 1 overshoot to be seen. This can lead, for example, to the fact that safety mechanisms against excessive pressure are triggered even though the pressure is not too high.

2 shows a gas pressure sensor 10 according to an embodiment. The gas pressure sensor 10 is in a pressure port 12th and in a connector housing 14th divided, which in the present case are clipped to one another as shown. This represents a typical, if not the only possible, division of a gas pressure sensor 10 represent.

In the pressure port 12th is a channel 20th educated. This has a connection opening on the left 22nd with which the gas pressure sensor 10 can be connected to a volume to be measured. On the right side of the canal 20th is a membrane 30th arranged, which deforms depending on the applied gas pressure. A sensor element is immediately adjacent 40 arranged, showing the deformation of the membrane 30th records and converts it into a signal. This signal is generated by electronics on an adjacent circuit board 50 in the connector housing 14th recorded and processed. For example, it can be attached to a component outside the gas pressure sensor 10 to be delivered.

In the canal 20th is in the present case a delay element in the form of a taper 60 educated. The rejuvenation 60 is such that the channel 20th between connection opening 22nd and membrane 30th a Place with a smaller diameter compared to the rest of the canal 20th having. This causes pressure to spread to the membrane 30th slowed down. Especially with a very rapid pressure increase at the connection opening 22nd which can occur, for example, when opening a valve to a pressure vessel, is thus to the right of the taper 60 in the canal 20th the pressure is slower than without the taper 60 increased, so that the occurrence of compressions and a resulting increase in temperature can be avoided.

In the embodiment shown, the taper is 60 in a component receiving the taper 61 formed, which has an external thread 62 has and in a complementary internal thread 24 of the canal 20th is screwed in. It should be mentioned, however, that there are other ways of forming a taper 60 are possible, for example tapering 60 also directly as a corresponding deformation of the channel 20th surrounding material of the pressure port 12th be trained.

3rd shows a gas pressure sensor 10 according to a second embodiment. In contrast to running 1 there is no taper, but rather it is in the channel 20th a delay element in the form of a heat dissipation element 70 arranged. In the present case, this is designed as a sintered lattice. It is a grid that, on the one hand, transfers gas to the membrane 30th lets through, but on the other hand has good thermal conductivity and thus dissipates resulting heat. If, due to the compression already mentioned, there is therefore an increase in the temperature immediately adjacent to the membrane with rapid increases in pressure 30th comes, a corresponding temperature increase is caused by the heat dissipation element 70 attenuated, which reduces or avoids the initially described effect of a brief increase in the signal. Also the heat dissipation element 70 can for example as referring to 2 can be screwed in or other mounting options can be used.

4th shows a gas pressure sensor 10 according to a third embodiment. In contrast to the embodiment of 2 is the rejuvenation 60 in a welded element 80 formed, which with a weld seam 62 on the rest of the gas pressure sensor 10 is welded on. This makes it part of the pressure port 12th . Between the welded element 80 and the rest of the gas pressure sensor 10 is a first sealing ring 84 arranged to reliably prevent gas leakage. Furthermore, in this exemplary embodiment it is also shown that it surrounds the connection opening 22nd a second sealing ring 86 is arranged, by means of which a connection to a volume, the gas pressure of which is to be measured, is sealed. A corresponding design can also be used in other exemplary embodiments.

5 shows schematically a gas supply arrangement 100 according to an embodiment. The gas supply arrangement 100 has a pressure vessel 110 with a valve connected to it 120 on. In the present case, it is a tank valve which, for example, is also in the pressure vessel 110 can be integrated. At the valve 120 is a sampling line 130 connected, which leads to a consumer, not shown, such as an internal combustion engine or a fuel cell. An associated gas flow is indicated by an arrow on the right.

At the sampling line 130 is a gas pressure sensor 10 connected. This can for example according to one of the with reference to 2 to 4th described embodiments be formed. By means of such a gas pressure sensor 10 can be the pressure in the sampling line 130 can be measured and the advantages described can be achieved, in particular when the valve is opened 120 and a consequent very rapid pressure increase in the extraction line 130 it can be avoided that there is an overshooting of an output signal of the gas pressure sensor 10 comes.

For reasons of legibility, the expression “at least one” has been partially omitted for the sake of simplicity. If a feature of the technology disclosed here is described in the singular or indefinitely (e.g. the / a pressure vessel, the / a withdrawal line, etc.), the plurality of these should also be disclosed at the same time (e.g. the at least one pressure vessel, the at least one withdrawal line Etc.).

The term “essentially” (eg “essentially corresponds to the container pressure”) in the context of the technology disclosed here includes the exact property or the exact value (e.g. “corresponds to the container pressure”) as well as irrelevant for the function of the property of the value Deviations (eg "tolerable deviation from the container pressure").

The preceding description of the present invention is for illustrative purposes only and not for the purpose of limiting the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents.

List of reference symbols

10:

Gas pressure sensor

12:

Discharge port

14:

Connector housing

20:

channel

22:

Connection opening

24:

inner thread

30:

membrane

40:

Sensor element

50:

Circuit board

60:

rejuvenation

61:

Component

62:

External thread

70:

Heat dissipation element

80:

welded element

82:

Weld

84:

first sealing ring

86:

second sealing ring

100:

Gas supply arrangement

110:

pressure vessel

120:

Valve

130:

Sampling line

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 406/2010 [0031]
• EP 29/2009 [0031]

Claims (11)

Gas pressure sensor (10), comprising - a connection opening (22), - a membrane (30) which deforms depending on a gas pressure, - A channel (20) which leads from the connection opening (22) to the membrane (30), - A sensor element (40) for detecting the deformation of the membrane (30) and for generating a signal based thereon, - At least one delay element (60, 70) which is arranged in the channel (20) and delays a pressure spread in the channel (20) and / or a temperature increase in the channel (20). Gas pressure sensor (10) Claim 1 - wherein a delay element (60, 70) is designed as a taper (60) compared to the adjacent part of the channel (20). Gas pressure sensor (10) according to one of the Claims 1 or 2 - wherein a delay element (60, 70) is designed as a heat dissipation element (70). Gas pressure sensor (10) Claim 3 - The heat dissipation element (70) being designed as a filter or as a sintered filter. Gas pressure sensor (10) according to one of the preceding claims, - Which has exactly one delay element (60, 70). Gas pressure sensor (10) according to one of the Claims 1 to 4th - which has a first delay element (60, 70) and a second delay element (60, 70), - wherein the first delay element (60, 70) is designed as a taper (60) compared to the adjacent part of the channel (20), and - wherein the second delay element (60, 70) is designed as a heat dissipation element (70). Gas pressure sensor (10) according to one of the preceding claims, - which has a pressure port (12) and a plug housing (14), - wherein the connection opening (22), the channel (20) and the membrane (30) are arranged in the pressure port (12), - wherein the sensor element (40) is arranged in the connector housing (14), and - The pressure port (12) and the connector housing (14) are connected to one another. Gas pressure sensor (10) according to one of the preceding claims, - wherein the delay element (60, 70) or a component (61) containing the delay element (60, 70) has an external thread (62) and is screwed into a complementary internal thread (24) of the channel (20). Gas pressure sensor (10) according to one of the preceding claims, - which has an element (80) welded to the rest of the gas pressure sensor (10), in which the delay element (60, 70) is arranged. Gas pressure sensor (10) according to one of the preceding claims, - wherein the delay element (60, 70) has a length of 10% to 30% of a length of the channel (20). A gas supply arrangement (100) comprising: - a pressure vessel (110) for storing gas, - A removal line (130) which is connected to the pressure vessel (110), - A valve (120) for switching or controlling a gas flow, the valve (120) being arranged in the extraction line (130) or between the extraction line (130) and the pressure vessel (110), - A gas pressure sensor (10) according to one of the preceding claims, the connection opening (22) of which is connected to the extraction line (130), the valve (120) being located between the gas pressure sensor (10) and the pressure vessel (110).

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