Valve

Abstract

The invention relates to a valve (1), in particular a vacuum valve, for metering a volumetric flow rate through a flow opening (2), the valve (1) having a valve disk (3) for closing the flow opening (2) in the closed position of the valve (1) and at least two longitudinally extending valve stems (4, 5), the valve stems (4, 5) being fastened to the valve disk (3) at locations spaced apart from one another and the valve stems (4, 5) being arranged in the closed position of the valve (1). Each of the valve rods (5, 5) is driven in a linearly displaceable manner by a respective valve drive (6, 7) of the valve (1) in order to adjust the valve disk (3), only some of the valve rods (4) are driven in a linearly displaceable manner by its valve drive (6) over the entire adjustment path (10) of the valve disk (3) between the closed position and the maximum open position.

Description

Technical Field

[0001] The invention relates to a valve, in particular a vacuum valve, for metering a volume flow through a flow opening, wherein the valve comprises a valve disk for closing the flow opening in a closed position of the valve and at least two valve stems extending longitudinally in each case, wherein the valve stems are fixed to the valve disk at locations spaced apart from one another and each of the valve stems is driven by its own valve drive in a linearly movable manner to adjust the valve disk. Background Art

[0002] Valves of this type are used, in particular in vacuum technology, for metering volume flows, i.e. the inflow or outflow of a fluid, in particular a gas, through a flow opening. These are primarily flow openings through which a fluid flows into or out of a process chamber. With the aid of these valves, the volume flow through the flow opening can be metered well. Valves of this type are described, for example, in US Pat. No. 10,156,299 B2. Figure 5 a and 5b. Summary of the invention

[0003] The object of the present invention is to provide a valve of the type mentioned at the outset which has a reduced energy requirement.

[0004] This is achieved by a valve according to claim 1 .

[0005] According to the invention, provision is therefore made for only some of the valve stems to be driven by their valve drive in a linearly displaceable manner over the entire adjustment path of the valve disk between the closed position and the maximum open position.

[0006] It is particularly preferably provided that only one of the valve rods is driven by its valve drive in a linearly displaceable manner over the entire adjustment path of the valve disk between the closed position and the maximum open position.

[0007] Thus, in the present invention, only a part of the valve drives, preferably only one of the valve drives, works on the entire regulating path of the valve drive, whereby the valve can be operated particularly energy-efficiently. In addition, the valve can be manufactured relatively cost-effectively.

[0008] Advantageously, provision is made for the valve rod to be driven by its respective valve drive only in a linearly displaceable manner.

[0009] In the invention, provision is advantageously made for at least one of the valve stems to be driven by its valve drive in a linearly displaceable manner only over a portion of the adjustment path of the valve disk towards and away from the closing position.

[0010] This can be achieved, for example, in that at least one of the valve stems is driven linearly by its valve drive only over a portion of the adjustment path of the valve disc toward the closed position and away from the closed position, and the at least one valve stem is decoupled from its valve drive over another portion of the adjustment path of the valve disc toward the maximum open position and away from the maximum open position. In the embodiment of the invention, the linear drive for at least one of the valve stems, which is driven linearly by its valve drive only over a portion of the adjustment path of the valve disc toward the closed position and away from the closed position, works only for pressing the valve disc onto the valve seat and / or for lifting the valve disc from the valve seat. The remaining movement of the valve disc is achieved only by the valve drive of the other valve stem or stems.

[0011] The valve stems can in principle consist of different materials. It can also be provided that one of the valve stems consists of a first material and the other valve stem or the other valve stems consist of another material. However, a preferred variant of the invention provides that the valve stems consist of the same material, preferably steel. Preferably, the valve stem consists of steel, in particular stainless steel.

[0012] Valves of this type are usually installed in such a way that the valve disk is located in the process chamber and the valve drive is located outside the process chamber. There are usually temperature differences between the area inside the process chamber and the area outside the process chamber, so that thermal deformations caused by the temperature difference need to be compensated, in particular so that no particles are generated or the generation of particles is avoided as far as possible.

[0013] In the valve according to the invention, a compensating element can be inserted between at least one of the valve stems and the valve disk in order to compensate for the thermally generated deformations.

[0014] A further valve according to the invention can provide that the valve stems are designed with different stiffnesses with respect to the deflection transversely to their respective longitudinal extension. In this variant of the invention, temperature-dependent longitudinal deformations of the valve plate can be compensated in that a valve stem with a lower stiffness with respect to the deflection transversely to its longitudinal extension deflects more strongly than a valve stem with a higher stiffness with respect to the deflection transversely to its longitudinal extension. Differences in temperature-dependent longitudinal deformations inside and outside the treatment chamber can thus be compensated particularly well without particles being generated as a result.

[0015] The different rigidities of the valve stem can be achieved, for example, by using different materials. However, it is preferably provided that the valve stem has different diameters at least partially. It should be noted here that valve stems with the same rigidity transversely to their respective longitudinal extensions can also have different diameters.

[0016] Regardless of how this is achieved, it is preferably provided that the resistance torque of a valve stem having a greater stiffness with respect to an offset transversely to its longitudinal extension is at least five times the resistance torque of the other valve stem, or in other words, at least five times the resistance torque of a valve stem having a smaller stiffness with respect to an offset transversely to its longitudinal extension.

[0017] The resistance torque is a measure of the mechanical resistance of the corresponding valve stem under load. In this case, the resistance torque can also be referred to as an axial resistance torque or a bending resistance torque, in relation to the deflection of the valve stem transversely to its corresponding longitudinal extension.

[0018] It is preferably provided that only the valve rod which is relatively rigid with respect to its deflection transversely to its longitudinal extension is driven by its valve drive in a linearly displaceable manner over the entire adjustment path of the valve disk between the closed position and the maximum open position.

[0019] In terms of language simplification, a valve stem having greater rigidity with respect to an offset transverse to its longitudinal extension may also be simply referred to as a valve stem having greater rigidity. In terms of language simplification, a valve stem having less rigidity with respect to an offset transverse to its longitudinal extension may also be simply referred to as a valve stem having less rigidity.

[0020] In the implementation of the invention, in principle all known linear valve drives are suitable as valve drives, which can be hydraulic valve drives, pneumatic valve drives or also electric valve drives.

[0021] It is again advantageous here if the valve drives of the valve rods are synchronized with one another over a portion of the adjustment path in which they work together.

[0022] The synchronization can be achieved by electronic or control-related coupling of the valve drive, but in the case of pneumatic and / or hydraulic valve drives, this can also be achieved by corresponding hydraulic or pneumatic connecting lines.

[0023] The through-flow opening is advantageously surrounded by a valve seat, against which the valve disc is pressed when the valve disc closes the through-flow opening in its closed position. The valve seat can be part of the valve or part of a valve seat plate which in turn is part of the valve. However, the valve seat can also be formed directly on the chamber wall of the process chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Further features and details of preferred embodiments are explained below by way of example in the description of the drawings.

[0025] Figures 1 to 11 A view showing a first embodiment of the present invention;

[0026] Figures 12 to 22 A view showing a second embodiment of the present invention;

[0027] Figures 23 to 26 A view showing a third embodiment of the present invention;

[0028] Figures 27 to 30 A view showing an embodiment of a fourth invention;

[0029] Figures 31 to 34 A view showing a fifth embodiment of the present invention: and

[0030] Figures 35 to 38 A view showing a sixth embodiment of the present invention. DETAILED DESCRIPTION

[0031] The valve 1 according to the invention is preferably a so-called vacuum valve, as is also shown in the embodiment shown here. Vacuum valves are usually used when they are to be operated in a specific environment and / or at a special pressure level. In particular, they can be called vacuum valves when they are operated with a pressure difference of less than or equal to 0.001 mbar (millibar) or 0.1 Pascal. However, they can also be called vacuum valves when they are designed for a pressure difference below the normal pressure, i.e. below 1 bar (bar). All valves 1 shown in the embodiment can be used as vacuum valves.

[0032] Figure 1 The valve 1 of the first exemplary embodiment is now shown in a perspective view separated from the process chamber 22, with the valve disk 3 in the maximum open position. Two valve rods 4 and 5 are fastened to the valve disk 3. Each valve rod 4, 5 is assigned its own valve drive 6 or 7.

[0033] All variants of the invention described below and therefore also according to Figures 1 to 11 In the first embodiment of the present invention, only a part of the valve stems of the valve stems 4, 5 are driven by their valve drive 6 or 7 in a linearly movable manner between the closed position and the maximum open position on the entire adjustment path 10 of the valve disk 3. In the embodiment shown here, the part number correspondingly includes only one valve stem 4. However, this is not necessarily the case. The part number can also include two or more valve stems. In the embodiment described below, the valve stem 5 is correspondingly driven by its valve drive 7 only on a partial path 11 of the adjustment path 10 of the valve disk 3 toward the closed position and / or away from the closed position in a linearly movable manner. In all the implementation variants described here, on the remaining other partial paths 12 of the adjustment path 10, the valve stem 5 is decoupled from its valve drive 7.

[0034] In accordance with Figures 1 to 11 In the first exemplary embodiment, the two valve rods 4 and 5 have the same diameter 8 or 9. In the first exemplary embodiment, the two valve rods are also designed to have the same rigidity with respect to the deflection transversely to their respective longitudinal extension.

[0035] The valve disk 3 for closing the through-opening 2 can be brought into a closed position and also into a maximum open position and into intermediate positions arranged therebetween by means of the valve drive 6 in order to thereby meter the volume flow of a fluid, now a gas or a liquid, flowing through the through-opening 2 .

[0036] The valve drive 6 is a known spindle drive. Specifically, this is achieved in this embodiment so that the valve stem 4 is fixed to a slide 20 at its end facing away from the valve disk 3, wherein the slide 20 is supported on a guide rail 19 in a linearly movable manner. The valve drive 6 has its own motor, an electric motor 16 in this case. The electric motor 16 drives the spindle 18 via a drive belt 17 in a known manner. A spindle nut 21 is located in the slide 20, which cooperates with the external thread of the spindle 18. The valve drive 6 can thus move the valve stem 4 along the guide rail 19 in a direction parallel to its longitudinal extension by means of the motor 16. The rod seal 23 surrounding the valve stem 4 ensures the sealing of the chamber interior 25. The corresponding rod seal 23 and the spindle drive are known and do not need to be further explained.

[0037] Of course, the valve drive 6 of the type implemented here can also be replaced by other suitable electric, pneumatic or hydraulic linear drives.

[0038] The valve drive 7 for the valve stem 5 has a drive pin 27 and a pin drive 28 for linearly moving it. An inclined surface 29 is located at the front end of the drive pin 27, which is pressed against a matching inclined surface 30 of the slide 20 of the valve stem 5 in the coupled state. By extending the drive pin 27 by means of the pin drive 28, the valve stem 5 is also pulled in the coupled state in the direction of the closed position of the valve disk 3. For opening, the drive pin 27 is retracted to such an extent that it releases the slide 20, so that the valve disk 3 can then be moved into an intermediate position and also into a maximum open position only by means of the valve stem 4 and its valve drive 6.

[0039] Advantageously, the valve drives 6 and 7 of the valve stems are synchronized with one another on the part 11 of the regulating path 10 in which the valve drives work together. In the embodiment shown here, this can be achieved, for example, by corresponding electrical control of the valve drives 6 and 7, which is not shown in detail here. In pneumatic or hydraulic drives, this can also be achieved by corresponding control of the pressure supply.

[0040] The through-opening 2 is formed in the valve seat plate 15 in the first exemplary embodiment and also in the other exemplary embodiments shown and is Figure 3, as shown in FIGS. 4 and 5 , it is also constructed in the corresponding process chamber 22. In the embodiment shown here, the valve seat 14 is located in the valve seat plate 15, into which the valve disc 3 is pressed in the closed position. The valve seat 14 and the valve seat plate 15 are parts of the valve 1 in this embodiment. However, it can also be provided that the valve seat plate 15 is eliminated. The valve seat 14 can then be constructed directly in the chamber wall of the process chamber 22 surrounding the flow opening 2. In the embodiment shown, the seal 13 for sealing the flow opening 2 in the closed position of the valve disc 3 is located in the valve disc 3. However, the corresponding seal 13 can of course also be realized in the valve seat 14 or not only in the valve disc 3 but also in the valve seat 14.

[0041] Figure 2 A schematically illustrated top view of a process chamber 22 is now shown with respect to a first exemplary embodiment, Figure 2 The invisible origin Figure 1 The valve 1 is arranged on the lower side of the process chamber. Figure 2 In the top view, only the section lines AA, BB and CC are marked. Figures 3 to 5 A sectional view along the section line AA is shown, wherein the valve disk 3 of the valve 1 is Figure 3 In the closed position, Figure 4 In the middle position Figure 5 in the maximum open position. Figures 6 to 8 A sectional view along the section line BB is shown, wherein the valve disk 3 is Figure 6 In the closed position, Figure 7 In the middle position Figure 8 in the maximum open position. Figures 9 to 11 A sectional view along the cutting line CC is shown, wherein the valve disk 3 is Fig. 9 In the closed position, Fig.10 In the middle position and in Fig.11 in the maximum open position. Figures 3 to 11It can be clearly seen in the figure that the valve drives 6 and 7 are located with their drive housings 26 outside the chamber interior 25 of the process chamber 22, while the valve disk 3 is always arranged in the chamber interior 25 in all its positions. In the chamber interior 25, there is usually a different temperature level than outside the process chamber 22. The valve disk 3 has the temperature of the chamber interior 25, while the valve drives 6 and 7 basically have the temperature outside the process chamber 22. If the temperatures in the chamber interior 25 and in the process chamber 22 change relative to each other, this leads to thermally induced longitudinal changes in the valve disk 3, but also in the valve drives 6 and 7. These different temperature-induced longitudinal changes are compensated in the first embodiment by means of a compensation element 39. The compensation element is arranged between the valve rod 5 and the valve disk 3 in this embodiment. The compensation element allows a relative movement between the valve rod 5 and the valve disk 3 in the longitudinal direction of the valve disk 3. As a result, different deformations caused by temperature can be compensated very well without causing the generation of particles. The compensating element 39 can be, for example, an elastically deformable intermediate layer, for example made of metal or elastomer, which allows a corresponding relative movement. The compensating element 39 can of course also be arranged additionally or alternatively between the valve stem 4 and the valve disk 3 .

[0042] exist Figures 3 to 11 2, through which the substance to be treated can be introduced into the chamber interior 25 and can be discharged from the treatment chamber 22. The introduction opening 24 can be closed by a known valve, which is not shown here. The valve 1 is used to close the flow opening 2 and, as described, to meter the volume flow of a gaseous or liquid fluid into or out of the chamber interior 25. The pumps and similar devices required for this are not shown here, but are known.

[0043] In the description of the following embodiments, only the differences from the first embodiment are also discussed.In addition, reference is made to the above description of the first embodiment, which description can be interpreted analogously to the second embodiment and the following embodiments.

[0044] In accordance with Figures 1 to 11 In the first embodiment of the present invention, the two valve rods 4 and 5 have the same diameter 8 or 9 and are also designed with the same rigidity with respect to the offset transversely to their respective longitudinal extension, which is not the case in the following embodiment. Figures 12 to 38In the variants, it is provided that the valve stems 4 and 5 are constructed with different rigidity with respect to the deflection transversely to their respective longitudinal extension. In this embodiment, it is preferably provided that the valve stems 4 and 5 are made of the same material, preferably steel or stainless steel. In order to construct the valve stems 4 and 5 with different rigidity with respect to the deflection transversely to their respective longitudinal extension, it is provided in all the following embodiments that the valve stems 4 and 5 have different diameters 8 and 9 at least in some areas. As already mentioned at the beginning, it is advantageous that the resistance torque of the valve stem 4 with greater rigidity with respect to the deflection transversely to its longitudinal extension is at least five times the resistance torque of the other valve stem 5. The diameter 8 of the valve stem 4 with greater rigidity is thus advantageously much larger than the diameter 9 of the valve stem 5 with less rigidity.

[0045] If the temperatures in the chamber interior 25 and in the process chamber 22 change relative to one another, this results in thermally induced longitudinal changes in the valve disk 3, but also in the valve drives 6 and 7. The different temperature-induced longitudinal changes are compensated in this exemplary embodiment described below by means of a corresponding deflection of the less rigid valve stem 5 in a direction transverse to its longitudinal extension. The aperture 38 through the wall of the process chamber 22 and the valve seat plate 15 which may be present is advantageously designed to be large enough in all the exemplary embodiments described below so that there is correspondingly large space for the deflection of the valve stem 5. The stem seal 23 can easily compensate for the thermally induced deflection of the valve stem 5.

[0046] exist Figures 12 to 22 A second embodiment of the present invention is shown in FIG. Fig.12 The valve 1 of the second exemplary embodiment is again shown in a perspective view, separated from the process chamber 22 . Fig.13 The process chamber 22 is shown with the section lines DD, EE and FF, corresponding to Figure 2 Top view of the . Figures 14 to 16 A cross-sectional view along the cutting line DD is shown, wherein Fig.14 The middle valve disc 3 is in the closed position. Fig.15 In the middle position Fig.16 in the maximum open position. Figures 17 to 19 Shown from Fig.13 A cross-sectional view along the cutting line EE, wherein Fig.17 The closed position is shown again. Fig.18 shows the middle position, and Fig.19 The maximum open position of the valve disk 3 is shown. The corresponding sectional view along the section line FF is shown in FIG. Figures 20 to 22 As shown in FIG. 3 , the valve disc 3 is Fig. 20 In the closed position, Fig.21 In the middle position and Fig. 22 in the maximum open position.

[0047] exist Fig.12The only difference to the first exemplary embodiment can already be clearly seen in . While in the first exemplary embodiment the two valve stems 4 and 5 have the same diameters 8 and 9 and are also constructed with the same rigidity with respect to the offset transversely to their respective longitudinal extension, this is not the case in the second exemplary embodiment. In the second exemplary embodiment, the valve stem 5 is constructed with a smaller height with respect to the offset transversely to their respective longitudinal extension than the valve stem 4. The valve stems 4 and 5 also have different diameters 8 and 9 accordingly. The less rigid valve stem 5 is driven by the valve drive 7 in a movable manner towards the closed position only over a partial path 11 of the adjustment path 10 of the valve disk 3. Over the remaining partial path 12 of the adjustment path 10, the valve stem 5 is decoupled from its valve drive 7. In . Fig.12 , 21 and 22, the decoupling state can be easily seen. Fig. 20 It can be seen how the valve drive 7 cooperates with the slide 20 of the less rigid valve stem 5 and thereby presses the valve disk 3 against the valve seat 14 in the direction of the closed position by means of a tensile force on the less rigid valve stem 5 .

[0048] according to Figures 23 to 26 The third embodiment is based on Figures 12 to 22 A variation of the second embodiment, wherein Fig.23 Shows something like Fig.12 , and Figures 24 to 26 Shows the corresponding Figures 20 to 22 In the third embodiment, the valve drive 7 of the valve stem 5 with less rigidity also has a drive pin 27 and a pin driver 28. However, the inclined surface 29 is omitted at the front end of the drive pin. Instead of the inclined surface, the displacement direction and the longitudinal extension of the drive pin 27 are arranged correspondingly obliquely, so that Fig.24 As shown, the less rigid valve stem 5 is displaced again by pressing the drive pin 27 onto the matching bevel 30 in the slide seat 20 of the less rigid valve stem 5, so that in this example the valve disk 3 is also displaced over the partial path 11 in the direction of the valve seat 14 by the two valve stems 4 and 5 and pressed onto the valve seat. The movement of the valve disk 3 in the opening direction is also shown in FIG. Fig.25 and 26 In the illustrated example, this is done only with the valve drive 6 and the relatively rigid valve stem 4 . The relatively rigid valve stem 5 is decoupled from the valve drive 7 over this sub-path 12 of the entire adjustment path 10 .

[0049] The valve drive 6 for the relatively rigid valve rod 4 is designed as in the first exemplary embodiment and is therefore not explained again. This also applies to the embodiment variants described below.

[0050] exist Figures 27 to 30In the fourth embodiment shown in , the valve drive 7 for the valve stem 5 with less rigidity is constructed in the form of an electromagnet 31. The electromagnet can not only be used to pull the valve stem 5 with less rigidity downward on the partial path 11 and thereby pull the valve disk 3 into the closed position. However, the electromagnet 31 can also be used to drive the valve stem 5 in the direction of the open position on the partial path 11 when the valve disk 3 is open by corresponding pole changes. Otherwise, the fourth embodiment is implemented like the third embodiment, so no further explanation is required. Fig. 27 In any case, a perspective view is shown, and Figures 28 to 30 The second embodiment is shown Figures 20 to 22 The corresponding view.

[0051] according to Figures 31 to 34 The fifth embodiment of the present invention differs from the second, third and fourth embodiments only in the configuration of the valve drive 7 for the valve stem 5 of lower rigidity. The valve drive 7 has a cam 32 that can be pivoted by means of a cam drive 33, which cooperates with a guide groove 34 on the slide 20 over the partial path 11 in order to thereby pull the valve stem 5 and thus also the valve disk 3 into the closed position. Fig.32 It can be seen in. Fig.33 and 34 The following position is shown in which the cam 32 is disengaged from the guide groove 34 and thus the valve stem 5 is decoupled from the valve drive 7. In this variant, the valve drive 7 also serves essentially to pull the valve stem 5 over the last partial path 11 in the direction of the closed position 3 of the valve disk. All other movements are realized by means of the more rigid valve stem 4 and its valve drive 6.

[0052] In accordance with Figures 35 to 38 The corresponding view is shown again in the last embodiment of FIG. The valve drive 7 for the valve stem 5 of less rigidity has a gear 35 driven by means of a gear drive 36. The gear cooperates with a toothed rack 37 on the slide 20 of the valve stem 5 of less rigidity on the lower part path 11. As a result, the valve stem 5 of less rigidity can be driven in the direction of the closed position of the valve disk 3, but can also be driven in the opposite direction away from the closed position on the part path 11. The remaining movement is also realized here on the part path 12 only by means of the valve stem 4 of greater rigidity and its valve drive 6. Figures 35 to 38 The type of view in is selected according to the above-mentioned embodiment.

[0053] List of Reference Numerals

[0054] 1 Valve

[0055] 2 Flow ports

[0056] 3 Valve disc

[0057] 4 Valve stem

[0058] 5. Valve stem

[0059] 6 Valve drive

[0060] 7 Valve drive

[0061] 8 Diameter

[0062] 9 Diameter

[0063] 10 The entire adjustment path

[0064] 11 Partial trail

[0065] 12 Partial trail

[0066] 13 Seals

[0067] 14 Valve seat

[0068] 15 Valve seat plate

[0069] 16 Motor

[0070] 17 Drive belt

[0071] 18 Spindle

[0072] 19 Rails

[0073] 20 Slide

[0074] 21 Spindle nut

[0075] 22 Processing Room

[0076] 23 Rod seal

[0077] 24 Introduction opening

[0078] 25 Interior space

[0079] 26 Drive housing

[0080] 27 Drive pin

[0081] 28-pin driver

[0082] 29 bevel

[0083] 30 Matching bevel

[0084] 31 Electromagnet

[0085] 32 Cam

[0086] 33 Cam drive

[0087] 34 Chute

[0088] 35 Gear

[0089] 36 Gear drive

[0090] 37 Rack

[0091] 38 Through

[0092] 39 Compensation elements.

Claims

1. A valve (1), in particular a vacuum valve, for metering a volume flow through a flow opening (2), wherein: The valve (1) comprises a valve disk (3) for closing the flow opening (2) in the closed position of the valve (1) and at least two valve stems (4, 5) respectively extending longitudinally, wherein the valve stems (4, 5) are fixed to the valve disk (3) at locations spaced apart from each other, and each of the valve stems (4, 5) is driven in a linearly movable manner by its own valve drive (6, 7) of the valve (1) to adjust the valve disk (3), characterized in that only a portion of the valve stems (4) are driven in a linearly movable manner by their valve drive (6) over the entire adjustment path (10) of the valve disk (3) between the closed position and the maximum open position.

2. The valve according to claim 1, characterized in that Only one of the valve stems (4) is driven by its valve drive (6) in a linearly movable manner over the entire adjustment path (10) of the valve disk (3) between the closed position and the maximum open position.

3. The valve (1) according to claim 1 or 2, characterized in that At least one of the valve stems (5) is driven by its valve drive (7) in a linearly movable manner towards and away from the closed position only over a partial path (11) of the adjustment path (10) of the valve disk (3).

4. The valve (1) according to claim 3, characterized in that At least one of the valve stems (5) is driven by its valve drive device (7) in a linearly movable manner toward the closed position and away from the closed position only on a partial path (11) of the adjustment path (10) of the valve disk (3), and the at least one valve stem is decoupled from its valve drive device (7) on another partial path (12) of the adjustment path (10) of the valve disk (3) toward the maximum open position and away from the maximum open position.

5. The valve (1) according to any one of claims 1 to 4, characterized in that The valve stems (4, 5) consist of the same material, preferably steel.

6. The valve (1) according to any one of claims 1 to 5, characterized in that The valve drives (6, 7) of the valve rods (4, 5) are synchronized with one another over a part (11) of the adjustment path (10) in which the valve drives work together.

7. The valve (1) according to any one of claims 1 to 6, characterized in that The valve stems (4, 5) have different diameters (8, 9) at least in certain areas.

8. The valve (1) according to any one of claims 1 to 7, characterized in that The valve rods (4, 5) are designed to have different rigidities with respect to a deflection transversely to their respective longitudinal extension.

9. The valve (1) according to claim 8, characterized in that The resistance torque of the valve stem (4) with greater rigidity with respect to an offset transverse to its longitudinal extension is at least five times greater than the resistance torque of the other valve stem (5).

10. The valve (1) according to claim 8 or 9, characterized in that The valve stem (4), which has a greater rigidity only with respect to the deflection transversely to its longitudinal extension, is driven by its valve drive (6) in a linearly movable manner over the entire adjustment path (10) of the valve disk (3) between the closed position and the maximum open position.

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