Gas introduction valve with bellows drive

Abstract

The present invention relates to a gas inlet valve (1) for the controlled introduction of a fluid into a vacuum process chamber, the gas inlet valve (1) comprising a gas distribution unit (2) with an internal volume (23) having a sealing surface (24) in the internal volume (23), a positioning unit (31) with a valve disc (32) projecting into the internal volume (23), a drive unit (3) connected to the positioning unit (31) outside the gas distribution unit (2), and a flexible sealing element (25) connected to the gas distribution unit (2) and the positioning unit (31) and atmospherically isolating the drive unit (3) from the internal volume (23). The drive unit (3) comprises an expansion element (11) whose spatial extension is changeable by changing the expansion volume, and the drive unit (3) comprises a compressed air passage connected to the expansion volume for pressurizing and expanding the expansion volume. The gas introduction valve (1) has connecting units (15a, 15b), which are connected to a drive unit (3) and a position adjustment unit (31), and are arranged so that when the expansion volume changes, the connecting units (15a, 15b) are moved and the position adjustment unit (31) is moved.

Description

[Technical Field]

[0001] The present invention relates to a gas inlet valve for admitting fluid into a vacuum process chamber. [Background technology]

[0002] Such vacuum process chambers are used in integrated circuit (IC) manufacturing, semiconductor manufacturing, flat panel manufacturing, or substrate manufacturing, and for at least some of the process steps, the vacuum chamber is evacuated and then filled with process gases. The manufacturing must be carried out in a protected atmosphere and, as far as possible, free from contaminant particles. The evacuation is carried out by a vacuum valve connecting the vacuum process chamber to a vacuum pump, which differs in its design and technical requirements from the gas inlet valve.

[0003] Such a vacuum chamber further has at least one or two vacuum chamber openings through which materials to be processed can be moved into and / or out of the vacuum chamber. For example, in a manufacturing facility for semiconductor wafers or liquid crystal substrates, sensitive semiconductor or liquid crystal materials pass sequentially through multiple vacuum process chambers, each of which processes the material using a processing device.

[0004] The component can be lowered onto a support, such as a potential plate (chuck), by lowering the support pins, for example, using a robot, onto the extended support pins of a lifting system. The robot arm, which typically supports the component, is then moved out of the chamber. After the component is lowered, the pins can be lowered and then disengaged from the component, i.e., no contact occurs between the pins and the component. After removing the robot arm and closing the chamber, the chamber is typically evacuated and then filled with process gas, and processing of the component can then begin.

[0005] The gas inlet valves are provided for filling the process chamber with one or more specific process gases or precursors to perform various substrate processing operations, such as the desired deposition of a material layer on the wafer or etching of the wafer surface, and specifically for releasing specific amounts of process fluid into the process chamber to initiate or accelerate a reaction between the process fluid and the wafer, for example, using a plasma.

[0006] Gas inlet valves are specifically designed for defined open-loop or closed-loop control of gas flow and are located, for example, in a piping system between a vacuum process chamber (or transfer chamber) and a gas source, atmosphere, or another vacuum process chamber. The opening cross-sectional area of ​​such gas inlet valves is typically smaller than the opening cross-sectional area of ​​a vacuum valve.

[0007] Depending on the field of use, the gas inlet valve can be used not only to completely open or close the opening, but also for open-loop or closed-loop control of the flow rate by continuously adjusting the opening cross-sectional area between an open position and an airtight closed position.

[0008] When introducing process gas into a vacuum chamber, it is extremely important to minimize fluid-technical effects within the chamber and to quickly and accurately fill the chamber. For example, a predetermined amount or volume of a predetermined process gas should be introduced into the chamber with each opening cycle of a gas inlet valve. For this purpose, on the one hand, it is desirable to operate the valve quickly and accurately adjust the resulting valve opening cross-section.

[0009] Some processing steps are typically carried out at high process temperatures, in particular above 100° C. and above 150° C. In this regard, corresponding temperature regulation of components in contact with the process gas is desirable, in order to avoid non-uniform fluid flow or distribution in and on the component or undesired deposition processes.

[0010] In a typical gas inlet valve, such high temperatures can cause a corresponding temperature rise throughout the valve, which can then lead to problems in the drive mechanism and / or electronics, especially in the area of ​​the drive. Furthermore, temperature regulation of the entire valve can result in a corresponding heat loss due to waste heat. Summary of the Invention [Problem to be solved by the invention]

[0011] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an improved gas inlet valve for vacuum processes, in order to avoid the above-mentioned drawbacks.

[0012] In particular, it is challenging to provide rapid, continuous, and accurate injection of process gases into a vacuum process chamber through a gas inlet valve over a wide temperature range. [Means for solving the problem]

[0013] The present invention relates to a gas introduction valve with a drive unit having an expansion element, in particular a bellows. The expansion of the expansion element can generate a force for opening the valve. This expansion can be achieved, in particular, by introducing compressed air into the expansion element. The opening force, and therefore the range of the open position of the valve disc, can be controlled by adjusting the internal pressure in the expansion element.

[0014] The gas inlet valve further comprises a return element, in particular a spring, which presses the valve disc of the valve against the valve seat and thus blocks the flow path for the fluid through the valve. An actuator can be used to generate an opening force that acts against the restoring force generated by the return element, thus opening the valve.

[0015] In the context of the present invention, a fluid is understood to mean at least one gas, a gas mixture, a liquid, a precursor-containing gas, or a gas-liquid mixture. The fluid may in particular be a process gas or a precursor gas.

[0016] The valve disc and / or valve seat (sealing surface) may have a sealing ring that is pressed or crushed between the valve disc and the valve seat in the closed position. The crushing occurs due to the preload of the return element and ensures gas-tight separation of the gas inlet from the gas outlet.

[0017] Controlling the duration of pressurization of the expansion element also allows for the amount of fluid flowing through the valve, for example, to a vacuum chamber, to be regulated for each valve opening cycle.

[0018] Accordingly, the present invention relates to a gas inlet valve for controlled fluid flow into or through a vacuum process chamber. The gas inlet valve includes a gas flow unit having a gas inlet, a gas outlet, and an interior volume. The interior volume connects the gas inlet and the gas outlet. The gas flow unit further includes a sealing surface within the interior volume.

[0019] The gas inlet valve further includes a position adjustment unit having a valve disc that protrudes into the internal volume, the valve disc being disposed within the internal volume, and the position adjustment unit is supported so as to be movable in a closing direction and an opening direction along a position adjustment axis.

[0020] The gas inlet valve further includes a drive unit connected to the positioning unit outside the gas flow unit and configured to adjust the position of the positioning unit along the positioning axis, and the drive unit can move the valve disc in an opening direction to an open position where the valve disc is spaced from the sealing surface and fluid is allowed to flow through.

[0021] Furthermore, a flexible sealing element is provided, which is connected to the gas flow unit and the positioning unit and atmospherically separates, in particular seals, the drive unit from the internal volume, and is particularly configured as a metal film.

[0022] According to the invention, the drive unit has an expansion element with a variable expansion volume, and a change in spatial extension of the expansion element is accompanied by a change in the expansion volume. The drive unit further has a compressed air passage connected to the expansion volume for pressurizing and expanding the expansion volume.

[0023] The gas introduction valve further has a connecting unit, which is connected to the drive unit and the position adjustment unit and is arranged so that the connecting unit is moved and the position adjustment unit is moved when the expansion volume changes.

[0024] The present invention therefore relates to a gas inlet valve with an actuator which implements an alternative actuation concept instead of known actuation methods for such valves, such as pneumatic actuation or mechatronic actuation with an electric motor, etc. The alternative actuation with an expansion element offers the advantage of a robust operation, in particular without heat-sensitive (electronic) components, and provides for fast and precise actuation of the valve opening.

[0025] The valve is furthermore particularly advantageously designed for use at high temperatures. For this purpose, the expansion element may be especially designed so that respective fluid passages are provided solely for its ventilation and exhaust, and these fluid passages are connected to the expansion element and to external units for supplying and / or receiving fluids, respectively. The expansion element itself may form a closed volume in the drive unit without the need for separate sealing (as is necessary, for example, in pneumatic systems).

[0026] The sealing of the gas flow unit is effected by flexible, particularly heat-resistant, sealing elements of the drive.

[0027] This allows all components involved in the movement and sealing to be arranged and configured in such a way that their functionality is maintained completely and without defects, regardless of the temperature regulation of the valve.

[0028] Thus, according to one embodiment, the spatial extension of the expansion element can be increased by pressurizing the expansion volume, and the valve disc can be movable in the opening direction by the position adjustment unit.

[0029] In one embodiment, the gas inlet valve may have one (or more) return elements, in particular spring or elastic elements, which are arranged to provide a restoring force acting in the closing direction to the position adjustment unit. The return elements can thus cooperate with the position adjustment unit to provide a preload force that presses the valve disc in the closing direction. The return elements are in a correspondingly preloaded state, in particular in the open position of the valve.

[0030] By applying pressure to the expansion volume or the expansion element, an opening force can be generated in the opening direction, which counteracts the restoring force. The return element can in particular be in operative contact or operatively connected to the position adjustment unit.

[0031] In one embodiment, the drive unit may have a separate compressed air passage connected to the expansion volume for exhausting the expansion volume, and by exhausting and shrinking the expansion volume, the valve disc may be brought into a closed position in the closing direction, where the valve disc contacts a sealing surface, thereby preventing gas flow.

[0032] Alternatively, the filling, i.e., pressurization, and venting, i.e., relieving overpressure in the expansion element, can occur through separate fluid passages.

[0033] In one embodiment, the gas introduction valve may have at least one separate expansion element with a variable expansion volume.

[0034] The gas inlet valve may in particular have at least one further compressed air passage for pressurizing and expanding at least one further expansion volume.

[0035] The connection unit may in particular be connected to the expansion element and / or to at least one further expansion element.

[0036] By providing at least one (or several) further expansion elements, the force acting on the positioning unit in the opening direction can be further increased or even multiplied. The total force that can be generated in this way can in particular be greater than the force provided by an individual expansion element. Furthermore, a force sufficient to open the valve can be provided correspondingly more quickly, thereby enabling the process performed by the gas introduction valve to be carried out correspondingly more quickly.

[0037] The expansion elements may be coupled, for example, by directly coupling the individual expansion elements to one another and by connecting the coupled expansion elements to the position adjustment unit (using a coupling unit). Alternatively or additionally, each of the provided expansion elements may be directly connected to a coupling unit and thereby movably coupled to the position adjustment unit.

[0038] In one embodiment, the drive unit may have a drive plate cooperating with the expansion element, the drive plate being supported for movement along the positioning axis and configured for connection with the coupling unit, in particular connected to the coupling unit.

[0039] The drive unit may in particular have a number of drive plates, in particular corresponding to the number of expansion elements provided, each of which cooperates with at least one expansion element and is movable by spatial extension or contraction of the expansion element. The drive plates may each be connected to a coupling unit, whereby force transmission of the expansion element may be performed on the position adjustment unit and converted into a movement of the valve disc.

[0040] In one embodiment, the drive unit may have a retaining element that is fixedly arranged on the valve. The retaining element is particularly arranged fixedly relative to the valve seat. The retaining element provides a retaining surface for the expansion element that faces away from the drive plate, so that the expansion element can only be extended in the direction of the drive plate. The retaining element is therefore particularly used to support the expansion element.

[0041] According to one embodiment, the position adjustment axis may extend centrally through the valve housing, the position adjustment unit may be centrally arranged and movably supported on the valve housing, and the coupling unit may have at least one connecting element for connecting the drive unit and the position adjustment unit, the connecting element being arranged radially spaced apart from the position adjustment unit within the valve housing and extending parallel to the position adjustment axis.

[0042] The gas inlet valve may have a valve housing, and the connecting element may extend parallel to a wall of the valve housing.

[0043] The connecting element may be configured, for example, as a web or rod, in particular made of metal. It is clear that a plurality of such connecting elements may be provided. Each of these connecting elements may be arranged radially spaced apart from the positioning unit in the valve housing and may each extend parallel to the positioning axis.

[0044] In one embodiment, the return element may be arranged radially between the connecting element and the position adjustment unit.

[0045] In one embodiment, the return element and the connecting element may be coupled to the position adjustment unit.

[0046] The coupling unit may in particular have a coupling element, which may be connected on the one hand to the positioning unit and on the other hand to the connecting element.

[0047] The connecting element may be constructed and arranged in such a way that the return element, in its preloaded adjustment, presses against the connecting element and thus applies a closing force to the valve disc acting in the closing direction.

[0048] In one embodiment, the expansion element may be configured as a bellows, in particular as a folded or corrugated bellows. The bellows may in particular be made of metal or a metal-containing material. Such a bellows may thus realize a closed body (volume) within the drive unit and may only have openings for the corresponding fluid passages (described above) that may provide an external connection (from the drive unit) for filling and / or exhausting.

[0049] Alternatively, the expansion element may be configured in a balloon-like manner, and the expansion element is preferably made from an elastic material.

[0050] Regardless of the shape or type of the expansion element, the cover of the expansion element is particularly designed to be airtight, which prevents possible contamination caused by the fluid (e.g. compressed air) provided for inflation from entering the drive unit.

[0051] In one embodiment, the expansion element may comprise or be made of a heat resistant material.

[0052] In one embodiment of the gas introduction valve, the sealing surface, valve disc and sealing element may have a circular cross section, the interior volume is at least partially cylindrical and the sealing surface is formed by a step in the interior volume.

[0053] The cylindrical shape of the internal volume is formed in particular by the gas-conducting unit as a peripheral surface and the sealing element as a bottom surface, and the gas inlet and the gas outlet are freely accessible to the internal volume via the peripheral surface, which means that the gas inlet and the gas outlet, respectively, may pass through the peripheral surface.

[0054] In particular, the disc divides the internal volume into a first partial volume and a second partial volume in the closed position, the gas inlet having free access to the first partial volume and the gas outlet having free access to the second partial volume.

[0055] The gas outlet has free access in particular to the vacuum process chamber in a specified arrangement in relation to the vacuum chamber, and the gas inlet has free access in particular to a process gas source.

[0056] Further advantages of the present invention can be seen from the detailed description and drawings. [Brief explanation of the drawings]

[0057] [Figure 1] 1 is a cross-sectional view of one embodiment of a gas introduction valve according to the present invention. [Figure 2] 2 is a cross-sectional view of the gas inlet valve of FIG. 1 rotated about an axis perpendicular to FIG. 1, according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0058] Figures 1 and 2 show an embodiment of a gas inlet valve 1 according to the invention. In Figure 1, the valve is shown rotated by 45° about the alignment axis V relative to the view in Figure 2. The gas inlet valve 1 comprises a gas distribution unit 2, which itself comprises a gas inlet 21, a gas outlet 22 and an internal volume 23, which has free access to or connects the gas inlet 21 and the gas outlet 22. The gas distribution unit 2 comprises a sealing surface 24 in the internal volume 23.

[0059] The gas inlet valve 1 further comprises a position adjustment unit 31 with a valve disc 32, which protrudes into the internal volume 23 and is supported outside the gas flow unit 2 so as to be positionably adjustable. The valve disc 32 is arranged in the internal volume 23 and is supported so as to be movable along a position adjustment axis V in a closing direction S and an opening direction O.

[0060] The gas inlet valve 1 further comprises preload or return elements 34a-34d configured as springs. The springs 34a-34d are arranged preloaded such that they exert a force in the direction of the valve seat and press the positioning unit 31 or the valve disc 32 against the sealing surface 24, i.e. in the closing direction S.

[0061] The disk 32 is pressed into the closed position against the sealing surface 24 via a spring preload. A sealing ring 33 is used to provide a gas-tight seal. The sealing ring is arranged on the disk 32 (as shown here) or (in other embodiments) on the sealing surface 24. The sealing ring may be made of, in particular, an elastomer, a thermoplastic, a metal, etc., and may have a shape adapted to the shape of the disk 32 (for example, an O-ring) or may be vulcanized to the disk 32.

[0062] The gas inlet valve 1 further comprises a flexible sealing element 25, which in the illustrated embodiment is embodied as a membrane, in particular as a metal membrane, which is connected to the gas flow unit 2 and the positioning unit 31 and thereby seals the internal volume 23. The flexibly configured membrane 25 thereby provides a flexible sealing of the internal volume 23, in particular with respect to the drive unit 3.

[0063] The gas inlet valve 1 also has a similar drive unit 3, which is connected to an adjustment unit 31 outside the gas flow unit 2 and allows adjustment of the position of the adjustment unit 31 along an adjustment axis V. By means of the drive unit 3, the valve disc 32 can be brought in an opening direction O to an open position in which the valve disc 32 is spaced away from the sealing surface 24, thereby allowing gas to flow through the internal volume 23 between the gas inlet 21 and the gas outlet 22.

[0064] The drive unit 3 comprises an expansion element 11 with a variable expansion volume. The spatial extension of the expansion element 11 can be varied by changing the expansion volume (and vice versa). The expansion element 11 can be configured, for example, as a bellows, in particular as a sector bellows or a corrugated bellows.

[0065] The expansion element 11 may be made from a metal-containing material. Alternatively, the expansion element 11 may be made from an elastic material.

[0066] Furthermore, a compressed air passage 12 is provided. The compressed air passage 12 is connected to the expansion element or expansion volume and is provided for pressurizing and expanding the expansion volume. The compressed air passage 12 may in turn be suitably connected to a compressed air source, for example a compressor or pneumatic system (not shown). This allows compressed air to be guided through the compressed air passage 12 to the expansion element 11 to expand the volume.

[0067] The gas introduction valve 1 further comprises a coupling unit which is connected to the drive unit 3 and to the position adjustment unit 31 and which is arranged such that when the expansion volume changes, the coupling unit is moved, thereby moving the position adjustment unit 31. The coupling unit may in particular be directly connected to the expansion element 11.

[0068] In the illustrated embodiment, the coupling unit comprises a connecting element 15a and a connecting element 15b. The connecting element 15a is configured here as a web, which is arranged radially spaced from the adjustment unit 31 in the valve housing and extends parallel to the adjustment axis V or to a wall of the valve housing. The connecting element 15a is connected at a first end to a drive plate 14 of the drive unit 3. The drive plate 14 is arranged to be movable along the adjustment axis V. A movement of the drive plate 14 correspondingly causes a movement of the connecting element 15a in a corresponding direction.

[0069] The connecting element 15a is further connected at its second end to a coupling element 15b, which itself provides a connection to the position adjustment unit 31, thereby transmitting the movement of the drive plate 14 to the position adjustment unit 31 and vice versa.

[0070] The drive plate 14 is operatively connected to the expansion element 11 and is constructed and arranged so that as the expansion element 11 expands, the drive plate 14 moves in an opening direction O. This causes the valve disc 32 to correspondingly move in the opening direction O as well, opening the valve 1, i.e., the valve disc 32 clears contact with the sealing surface 24 (valve seat) and allowing fluid flow.

[0071] On the other hand, movement of the drive plate 14 in the closing direction S causes compression of the expansion element 11 .

[0072] The gas inlet valve 1 can be opened by applying pressure to the expansion element 11 using the compressed air passage 12. The pressure in the expansion element 11 causes it to expand. Due to the design, this expansion occurs only in the opening direction O, accompanied by a shift of the drive plate 14. The face of the expansion element 11 opposite the drive plate 14 is operatively connected to a retaining element 13 that is fixed in position relative to the valve housing, so that the force generated by the expansion of the expansion element 11 can only move the drive plate 14.

[0073] The pressurization of the expansion element 11 to open the valve is particularly adjusted or selected so that the resulting compressive force on the drive plate 14 exceeds the restoring force provided by the springs 34a-34d, thus allowing movement of the drive plate 14.

[0074] The springs 34a-34d are tensioned in the illustrated embodiment by the connecting element 15b, which provides a restoring force for closing the valve 1. The springs 34a-34d may have their opposite ends arranged on the retaining element 13 as shown.

[0075] Thus, as already mentioned, to open the valve 1, compressed air is forced into the expansion element 11, which causes the valve disc 32 to lift off the sealing surface 24 (see FIG. 1). This movement is achieved via the working chain of the drive plate 14, the connecting element 15a, the coupling element 15b and the positioning unit 31.

[0076] To close the valve 1, the expansion element 11 can be vented. For this purpose, an exhaust passage (not shown) is preferably provided which can be opened and / or closed in a controlled manner and is connected to the expansion volume. When the exhaust passage is opened, compressed air escapes from the expansion element 11, so that the restoring force becomes greater than the compression force, which moves the valve disc 32 in the closing direction S.

[0077] Alternatively or in addition to a separate exhaust passage, exhaust can also be provided by the compressed air passage 12 .

[0078] The actuator of the valve 1 according to the invention is therefore advantageously designed so that the actuator mechanism is essentially formed by an expansion element, making it possible to completely dispense with a mechatronic actuator. This makes the operation of the actuator robust against temperature influences, advantageously ensuring reliable functioning of the gas introduction valve when using valves with fluids that are temperature-conditioned (to high temperatures), for example, to achieve improved reactivity. Corresponding temperature conditioning of the valve together with the actuator can therefore be carried out without adverse effects on the actuator, thereby avoiding uneven fluid flow or distribution or undesirable deposition processes in and on the valve components.

[0079] In an embodiment not shown, the drive unit of the gas introduction valve may have at least one further expansion element with a variable expansion volume, which may be connected to the compressed air passage and / or to at least one further compressed air passage in order to pressurize and expand the further expansion volume.

[0080] At least one further expansion element may be disposed parallel to the first expansion element and in direct operative connection with the drive plate.

[0081] Alternatively or additionally, at least one further expansion element may be arranged in series with the first expansion element, and the drive unit may have one or more further drive plates, which are in contact with the further expansion element and transmit the force generated by the application of pressure to the further drive plates.

[0082] At least one further drive plate may furthermore be connected to the connection element and provide direct force transmission to the connection element and thus against the restoring force of the spring.

[0083] Thus, by arranging multiple expansion elements on the drive unit, the force required to open the valve can be provided relatively quickly and / or sufficiently.

[0084] Although the present invention has been described based on exemplary embodiments, many other changes and modifications are possible without departing from the scope of the present invention. It is therefore intended that the appended claims cover such changes and modifications as fall within the true scope of the invention.

Claims

1. A gas inlet valve (1) for controlled admission of fluid into a vacuum process chamber, the gas inlet valve (1) comprising: a gas distribution unit (2) comprising a gas inlet (21), a gas outlet (22) and an internal volume (23) connecting said gas inlet (21) and said gas outlet (22), said internal volume (23) having a sealing surface (24); - a position adjustment unit (31) projecting into said internal volume (23) with a valve disc (32) arranged in said internal volume (23), said position adjustment unit (31) being supported so as to be movable along a position adjustment axis (V) in a closing direction (S) and in an opening direction (O); a drive unit (3) connected to the positioning unit (31) outside the gas flow unit (2) and adapted to adjust the position of the positioning unit (31) along the positioning axis (V), by which the valve disc (32) can be brought in an opening direction (O) to an open position in which the valve disc (32) is spaced from the sealing surface (24) and is in fluid communication; a flexible sealing element (25) connected to the gas flow unit (2) and the positioning unit (31) and atmospherically separating the drive unit (3) from the internal volume (23); In a gas introduction valve (1) having - the drive unit (3) comprises an expansion element (11) with a variable expansion volume, the spatial extension of which is modifiable by changing said expansion volume; - the drive unit (3) has a compressed air passage (12) connected to the expansion volume for pressurizing the expansion volume and expanding it; The gas introduction valve (1) has coupling units (15a, 15b) connected to the drive unit (3) and the position adjustment unit (31), and is arranged so that when the expansion volume changes, the coupling units (15a, 15b) are moved and the position adjustment unit (31) is moved. A gas introduction valve (1) characterized by the above.

2. 2. The gas introduction valve (1) according to claim 1, wherein the expansion volume can be pressurized to increase the spatial extension of the expansion element (11), and the valve disc is movable in the opening direction (O) by the position adjustment unit (31).

3. - the drive unit (3) has a separate compressed air passage connected to the expansion volume for exhausting the expansion volume; 3. A gas inlet valve (1) according to claim 1 or 2, wherein by venting and reducing the expansion volume, the valve disc (32) can be brought into a closed position in the closing direction (S), in which the valve disc (32) contacts the sealing surface (24), thus preventing gas flow.

4. 4. The gas inlet valve (1) according to claim 1, wherein the gas inlet valve (1) comprises at least one further expansion element with a variable expansion volume.

5. 5. The gas introduction valve (1) according to claim 4, wherein the gas introduction valve (1) has at least one other compressed air passage for pressurizing the at least one other expansion volume to expand the other expansion volume.

6. 6. The gas introduction valve (1) according to claim 4 or 5, wherein the connecting unit (15a, 15b) is connected to the expansion element (11) and / or to at least one further expansion element.

7. the position adjustment axis (V) extends centrally through the valve housing of the gas inlet valve (1), the position adjustment unit being centrally arranged and movably supported on the valve housing; A gas introduction valve (1) according to any one of claims 1 to 6, wherein the coupling unit has at least one connecting element (15a) for connecting the drive unit (3) and the position adjustment unit (31), the connecting element (15a) being arranged radially spaced apart from the position adjustment unit (31) in the valve housing and extending parallel to the position adjustment axis (V).

8. The gas introduction valve (1) according to any one of claims 1 to 7, wherein the gas introduction valve (1) has a return element (34a to 34d), in particular a spring, which is arranged to apply a restoring force acting in the closing direction (S) to the position adjustment unit (31).

9. The gas introduction valve (1) according to claim 8, which is dependent on claim 7, wherein the return elements (34a to 34d) are arranged radially between the connecting element (15a) and the position adjustment unit (31).

10. The gas introduction valve (1) according to claim 8, when dependent on claim 7, wherein the return element (34a-34d) and the connecting element (15a) are connected to the position adjustment unit (31).

11. 11. The gas introduction valve (1) according to claim 1, wherein the drive unit (3) has a drive plate (14) cooperating with the expansion element (11), the drive plate (14) being supported so as to be movable along the position adjustment axis (V) and configured for connection with the connecting unit (15a, 15b).

12. 12. The gas inlet valve (1) according to any one of claims 1 to 11, wherein the expansion element (11) is configured as a bellows, in particular as a folding bellows or a corrugated bellows.

13. 13. The gas inlet valve (1) according to any one of the preceding claims, wherein the expansion element (11) comprises or is made of a heat-resistant material.

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