SMOOTH-RUNNING PNEUMATIC VACUUM VALVE

Abstract

The invention relates to a vacuum transfer valve (1) with a valve wall (8) having an opening (2) and a valve seat (3) extending around the opening (2), a sealing plate (4) with a sealing side for gas-tightly closing the opening (2), and an actuating unit (10) coupled to the sealing plate (4) by means of a valve rod (5). The actuating unit is configured to move the sealing plate (4) from an open position (O), in which the sealing plate (4) releases the opening (2), to a closed position (C), in which the sealing side of the sealing plate (4) is pressed against the valve seat (3) and gas-tightly closes the opening (2), and back again. The actuating unit (10) comprises a first pneumatic actuator (11) coupled to the valve rod (5) and configured to provide movement of the sealing plate (4) in a first direction, and a second pneumatic actuator (14).which is coupled to the valve stem (5) and is configured to provide movement of the closure plate (4) in a second direction, a first pressure sensor (13) which is arranged and configured to measure a first actuating pressure in the first pneumatic actuator (11), a second pressure sensor (16) which is arranged and configured to measure a second actuating pressure in the second pneumatic actuator (14), a first fluid flow controller (12) which is arranged and configured to provide a defined actuating fluid flow to or from the first pneumatic actuator (11), and a second fluid flow controller (15) which is arranged and configured to provide a defined actuating fluid flow to or from the second pneumatic actuator (14).

Description

AREA OF INVENTION The invention relates to a pneumatically driven vacuum valve that provides smooth and homogeneous movement of the valve closure. BACKGROUND OF THE INVENTION Vacuum applications are typically carried out in vacuum chamber systems. These applications are used, for example, in IC, semiconductor, or substrate manufacturing, which must take place in a protected atmosphere as far as possible, without the presence of contaminating particles. The vacuum chamber systems comprise, in particular, at least one evacuable vacuum chamber, which is provided for receiving semiconductor elements or substrates to be processed or manufactured and which has at least one vacuum chamber opening through which the semiconductor elements or other substrates can be fed into and out of the vacuum chamber. For example, in a manufacturing plant for semiconductor wafers or liquid crystal substrates, the highly sensitive semiconductor or liquid crystal elements pass sequentially through several processing vacuum chambers, in which the parts located within the processing vacuum chambers are each processed by a processing device. The processing chambers typically have at least one transfer valve, the cross-section of which is adapted to the substrate and the robot, and through which the substrate can be inserted into the vacuum chamber and, if necessary, removed after the planned processing. Alternatively, a second transfer valve can be provided through which the processed substrate is removed from the hermetically sealed chamber. Furthermore, the processing system may include one or more peripheral units, which are used in particular to control or regulate the fluid flow into and / or out of the vacuum chamber. The peripheral units may be provided by a control valve located between the vacuum chamber and a vacuum supply unit or another vacuum chamber, or by a gas inlet valve, e.g., a mass flow controller, located upstream to supply a specific type and quantity of fluid to the vacuum chamber. A substrate to be processed, e.g., a wafer, is guided by a suitably designed and controlled robot arm, which can be moved through the opening in the processing chamber provided by the transfer valve. The processing chamber is then loaded by holding the substrate with the robot arm, inserting the substrate into the processing chamber, and depositing the substrate in a defined manner within the chamber. The processing chamber is then emptied accordingly. Since transfer valves (vacuum gate valves) are used, among other things, in the production of highly sensitive semiconductor components, particle generation, which is caused in particular by the actuation of a valve, and the number of free particles in the vacuum region of the valve chamber must be kept as low as possible. Particle generation is primarily a result of friction, for example from metal-to-metal contact and abrasion. The seal can be produced, for example, either by a gasket arranged on the closing side of the valve plate (valve closure), with the gasket pressed against the valve seat, which extends around the opening, or by an annular seal on the valve seat, against which the closing side of the valve plate is pressed. Various sealing devices are known in the prior art, for example from US 6,629,682 B2 (Duelli). A suitable material for annular seals is, for example, the elastic sealing material known under the trade name Viton®. Since the seals used are subject to above-average wear or can be destroyed if pressed with excessive force, the valves are designed so that differential pressure forces cannot act on the seals, or can only act on them to a limited extent. The seal should be pressed as uniformly as possible along its length, which requires a uniform contact pressure of the valve disc against the valve seat across the entire contact area. In particular, transverse loads on the seal should be kept to a minimum. In the case of transverse loads (perpendicular to a normal direction of the seal), there is a risk (e.g., in the case of O-ring seals) that they will be torn from their mounting, especially the groove in which they are fixed, or that the sealing material will be damaged and particles will be generated. Various designs of vacuum valves, in particular their drive technologies, are known from the prior art and aim to extend the service life of the seals used and also to provide improved process reliability. This is typically achieved through specific movement profiles of the valve closure of corresponding transfer valves (gate valves). In a first step, the valve closure, in particular a closure plate or valve disc, known, for example, from US 6,416,037 (Geiser) or US 6,056,266 (Blecha), especially of the L-type, is slid linearly over an opening that is substantially parallel to the valve seat, without contact between the valve closure and the valve seat during this process. In a second step, the valve closure is pressed against the valve seat via its closure side, so that the opening is sealed gas-tight. The described two-stage movement provides for pressing the seal almost exclusively vertically, without any transverse stress on the seal. The closing movement of such a gate valve, which occurs in two steps, can be achieved by various mechanisms. The closing plate, which is mounted, for example, on two connecting rods, is linked via these rods to a drive mechanism. This drive mechanism, due to a substantially linear movement along the axis of the connecting rods, allows the closing plate to be slid essentially parallel to the opening to be closed. The same drive mechanism can then be used to pivot the closing plate, which is then positioned at a distance from the opening and essentially parallel to the valve seat, in the direction of the valve seat, pressing the closing plate essentially perpendicularly against the valve seat. It is also possible to use only one connecting rod instead of two.The use of more than two connecting rods is also possible. Drive mechanisms that allow both an essentially linear sliding of the closure disc over the opening and an essentially perpendicular pressing of the closure disc against the valve seat, which runs around the opening, are known, for example, from US 64,431,518 B1, US 5,415,376 A, US 5,641,149 A, US 6,045,117 A, US 5,934,646 A, US 5,755,255 A, US 6,082,706, US 6,095,180, and US 6,629,682 B2. US 5,769,952 discloses an alternative method. The valve includes a mechanism that provides a change in the direction of movement of the valve closure simply by moving the valve stem in one direction. Therefore, an advantage of this type of gate valve is its relatively simple actuation design, since the connecting rod only needs to slide linearly. US 2008 / 0083897 A1 also discloses a mechanism to provide sequential longitudinal movement of the valve closure in two directions. By providing movement of the valve stem first in one direction and then in a direction essentially perpendicular to the first direction, closing and opening of the valve opening can be achieved by approaching and moving the valve stem in a direction parallel to the surface normal of the valve seat. This prevents particle generation. However, as mentioned, a disadvantage of sequentially moving the valve stem in two directions results in relatively long actuation periods for opening and closing the valve. Furthermore, a proposed mechanism for reversing the direction of movement using a single drive unit is comparatively complex, and in the event of maintenance or damage, highly skilled personnel are required to enable further operation of the valve. Another disadvantage of the aforementioned transfer valves is that the implemented movement profile, and in particular the pressure applied between the valve disc and the valve seat, is always the same. This applies to valve closures during maintenance, but also during a regular machining cycle, where such a pressure would typically be lower than during maintenance. Consequently, the sealing material is subjected to greater stress than necessary from a process perspective. Therefore, the service life of the sealing material is reduced accordingly. TASK OF INVENTION It is therefore the object of the present invention to provide an improved pneumatic vacuum valve for vacuum applications that reduces or avoids the aforementioned disadvantages. In particular, it is an object of the invention to provide an improved pneumatic vacuum valve with an improved pneumatic actuation system that enables reliable and rapid movement of the valve closure. Furthermore, it is an object of the present invention to provide an improved vacuum valve that provides flexibility in moving the valve closure and pressing the valve closure against the valve seat. These problems are solved by implementing the characterizing features of the independent claims. Features that further develop the invention in a different or advantageous way are found in the dependent claims. BRIEF SUMMARY OF THE INVENTION The method according to the invention proposes providing at least two individually controllable pneumatic actuators to move a valve closure of a vacuum transfer valve simultaneously in at least two (orthogonal) directions, in order to provide smooth and homogeneous movement of the valve closure. The method also makes it possible to adjust the movement profile of the valve closure depending on the desired application. Control of the pneumatic actuators is achieved by connecting fluid flow controllers to the actuators. The fluid flow controllers provide a defined pressure to the actuators by applying a defined quantity of actuating fluid per unit of time. A fluid flow controller can be a control valve configured to control and provide defined pressure or pressure changes in the actuator, particularly in the pneumatic cylinder of the actuator or in at least one chamber of the pneumatic cylinder. Alternatively or additionally, the control valve can be configured to control and provide a defined fluid flow or flow rates, or changes thereof, in the pneumatic actuator. The fluid flow controller can be a proportional control valve that is capable of providing a defined fluid flow depending on an applied control signal. Such a fluid flow controller can provide a defined fluid flow into a first and / or second pneumatic actuator, or a defined fluid pressure in the corresponding pneumatic actuator, depending on an applied control signal, where the control signal can provide a control voltage or a control current. Furthermore, setting the first control signal can include setting the control voltage or control current to provide movement of a motion element of an actuator according to motion information. Feedback regarding the pressure in one of the actuators can be provided by means of a suitable sensor. The invention relates to a vacuum transfer valve with a valve wall having an opening and a valve seat extending around the opening, and with a closure plate (a valve closure) having a closure side for gas-tight sealing of the opening. The vacuum transfer valve also includes a drive unit which is coupled to the sealing plate by means of a valve rod, i.e., a type of valve guide is provided to hold and move the sealing plate, and which is designed so that the sealing plate can be moved from an open position, in which the sealing plate releases the opening (no contact between the sealing plate and the valve seat), to a closed position, in which the closing side of the sealing plate is pressed against the valve seat and seals the opening gas-tight, and back again. The drive unit comprises a first pneumatic actuator coupled to the valve stem, configured to provide movement of the closure plate in a first direction. The drive unit further comprises a second pneumatic actuator coupled to the valve stem, configured to provide movement of the closure plate in a second direction. The first direction can be linear or longitudinal, or alternatively, rotational, e.g., movement of the locking plate around a corresponding axis of rotation. The second direction can also be linear or longitudinal, or alternatively, rotational, e.g., movement of the locking plate around a corresponding axis of rotation. At least one of the pneumatic actuators can comprise a cylinder divided into two chambers by a moving element. The moving element can preferably be a piston. A shaft can be connected to the moving element and can extend outside the inner volume of the cylinder. The shaft can provide the valve stem and can be configured to actuate the connected valve closure to be moved. The pneumatic actuator can further include a first fluid passage, which allows fluid flow into and out of the first or second chamber of the actuator. Furthermore, at least one pneumatic actuator can include a return element, in particular a spring. The return element can be connected to the moving element and can exert a return force on the moving element. The drive unit comprises a first pressure sensor, which is arranged and configured to measure a first actuation pressure in the first pneumatic actuator, and a second pressure sensor, which is arranged and configured to measure a second actuation pressure in the second pneumatic actuator. The pressure sensors are preferably arranged to measure the pressure in at least one chamber of the actuator. At least one of the pressure sensors can provide pressure feedback regarding a pressure acting on the moving element. In an alternative embodiment, at least one of the pressure sensors can be a flow meter to measure fluid flow from and / or into the correspondingly connected actuator. In an alternative embodiment, at least one of the pressure sensors can be a flow rate sensor. The drive unit comprises a first fluid flow controller arranged and configured to provide a defined actuating fluid flow to or from the first pneumatic actuator, and a second fluid flow controller arranged and configured to provide a defined actuating fluid flow to and from the second pneumatic actuator. The top-mounted configuration of a vacuum transfer valve allows the movement of the sealing plate (valve closure) to be controlled in a single, homogeneous motion, without requiring more than one separate movement step or sequence. This is because the sealing plate can be moved simultaneously in two directions, reaching the end positions of each direction essentially at the same time. Furthermore, since it is possible to control the pressures in the actuators, a pressing force for pressing the sealing plate against the valve seat can be set according to the required application criteria, resulting in less stress and wear on the sealing material. Thus, the seal provides a longer service life due to reduced wear. In one embodiment, the second pneumatic actuator can be coupled to the valve stem and the sealing plate. Such an arrangement allows for individual movement of the sealing plate in the second direction. In one embodiment, the second pneumatic actuator can be coupled to the valve rod in order to exert movement in the second direction on the valve rod and thereby provide a corresponding movement of the sealing plate. In one embodiment, the first and second pneumatic actuators are built as an integrated actuator unit to provide movements in both directions. In one embodiment, the first fluid flow controller and the second fluid flow controller can be subunits of a complete fluid flow controller, wherein the general fluid flow controller provides pressurization of the first and second pneumatic actuators. In one embodiment, the valve stem can support the sealing plate. According to one embodiment, the second pneumatic actuator can be coupled to the valve stem and the sealing plate, and can provide mobility of the sealing plate relative to the valve stem. With such an arrangement, direct actuation of the sealing plate in a direction parallel to an opening axis of the valve orifice can be provided, enabling it to approach and contact the valve seat in a normal direction. In one embodiment, the vacuum transfer valve can include a control unit configured to provide movement of the closure plate according to a motion profile by controlling the first fluid flow controller and the second fluid flow controller. The control unit can be configured to generate a corresponding control signal that, upon application, provides corresponding actuations of the fluid flow controllers. The motion profile can include information about the (nominal or target) positions of the closure plate in one or all directions over time, e.g., for a machining cycle. The motion profile can directly relate to or encompass a corresponding pressure profile applied to the relevant actuator to provide the desired motion. At least one actuation speed, one actuation acceleration and / or one sealing force (force to press the sealing plate against the valve seat) for the sealing plate can be defined by such a motion profile. In particular, the control unit can be configured to control the first fluid flow controller and the second fluid flow controller depending on pressure information provided by the first pressure sensor and the second pressure sensor. By measuring the pressures in the pneumatic actuators, i.e. in corresponding pressurized chambers of the actuators, direct feedback of a fluid flow can be provided in order to precisely control the pressurization of the actuators according to a motion profile used. In one embodiment, the control of the first fluid flow controller and the second fluid flow controller can be provided such that the movement of the closure plate includes simultaneous movement in the first direction and in the second direction. A corresponding motion profile can therefore include pressurization instructions for both fluid flow controllers or motion instructions for both actuators. In one embodiment, a first pressure profile can be provided to control the first fluid flow controller, and a second pressure profile can be provided to control the second fluid flow controller. According to one embodiment, the control unit can be configured to provide a set of motion profiles, each of which provides a superposition of a movement of the closure plate in the first direction and a movement of the closure plate in the second direction, wherein at least two of the set of motion profiles can be individually selected to be tracked by the closure plate. This allows a motion profile that matches the required application parameters to be automatically or manually selected by an operator in order to provide a correspondingly optimized movement behavior of the valve closure. In one embodiment, the control unit can include a motion profile planner which, when executed, generates the motion profile or sets it by adjusting the control of at least one of the first and second fluid flow controllers. Such functionality enables the individual creation of suitable motion profiles for specific applications. In particular, the motion profile planner may include non-adjustable basic conditions to ensure valve integrity when the valve is actuated with a generated or set motion profile. The basic conditions may include at least one of the following: • a motion offset with respect to a motion range of the shutter plate in the first direction relative to the second direction; • a speed limit for a movement of the shutter plate; • a limit for the rate of change of pressure of the actuating fluid, in particular a limit for the acceleration of the shutter plate; and • a limit with respect to the pressing of the shutter plate against the valve seat. For example, the movement offset can be defined to provide partially simultaneous movement in the first and second directions, but also separate movement, particularly to prevent the sealing plate from contacting the valve seat and continuing to move in the first direction, i.e., orthogonally to the opening axis. Such orthogonal movement could lead to damage to the sealing material of the sealing plate. Further basic conditions can be defined to prevent damage to the transfer valve during an unwanted movement. In one embodiment, a digital model, in particular a digital twin, of the vacuum transfer valve can be provided, wherein the digital model provides a description or determination of valve states depending on the pressure information. Such a model allows the structure and function of the valve to be derived at any given time by processing the pressure information. The model can be trained to provide (approximately) realistic behavior of the vacuum transfer valve, meaning that a specific pressure measurement can be performed and assigned to corresponding valve states. For example, several positions of the closure plate can be determined (e.g., by measurement), and corresponding pressure values ​​can be derived and assigned to the positions. The control unit can be further configured to derive a first control signal to control the first fluid flow controller and a second control signal to control the second fluid flow controller based on the digital model and pressure information. In particular, the control unit can be configured to derive a position of the closure plate depending on the print information and based on the digital model. Thus, the digital model enables the derivation of position information in real time using measured pressure values. Consequently, a type of motion tracking can be provided to monitor the actual valve state (state or position of the sealing plate) and compare it with a desired target state. In one embodiment, the vacuum transfer valve can include an environmental condition sensor, in particular a temperature sensor or a humidity sensor, to measure an environmental parameter, and the control unit can be configured to process the environmental parameter while providing the description or determination of valve states, in particular by adjusting the digital model or model parameters. This additional information provides more accurate modeling of the transfer valve and derivation of valve positions with correspondingly high precision. In one embodiment, the control unit can be configured to monitor the progression of the valve state during movement of the closure plate based on the digital model and pressure information (e.g., real-time tracking of the closure plate), to compare the monitored progression of the valve state with (known and / or stored) reference valve states relating to the (nominal or target) movement profile of the closure plate, and to derive valve operating information based on the comparison. This method provides monitoring of the valve's operation and the generation and provision of relevant information (warnings) to the operator, in order to be constantly aware of any malfunctions or the like. In one embodiment, the control unit can be configured to determine a long-term trend based on monitoring the progression of the valve state over several control cycles, derive valve state information based on the long-term trend, compare the valve state information with a predefined threshold, and generate maintenance information based on the comparison. Such derived information about the long-term trend, e.g., a long-term drift in the control of the vacuum valve, can provide relevant information about possible wear or leakage (e.g., concerning the actuating fluid supply), and based on this, maintenance of the valve can be planned or initiated. BRIEF DESCRIPTION OF THE DRAWINGS The valve according to the invention will subsequently be described in detail only as an example, with reference to specific exemplary embodiments, which are schematically illustrated in the drawings, and further advantages of the invention will also be discussed. The figures in detail: Figs. 1a-1c show an embodiment of a transfer valve known in the prior art. Fig. 2 shows a movement profile of the vacuum valve known in the prior art. Figs. 3a-3c show an embodiment of a vacuum transfer valve according to the invention. Fig. 4 shows a movement profile of a vacuum transfer valve according to the invention. Figs. 5a-5b show a pressure profile and movement profile of a vacuum transfer valve according to the invention. DETAILED DESCRIPTION OF THE DRAWINGS Figs. 1a-1c show an embodiment of a vacuum transfer valve 1 in the prior art, which is shown in different closing positions. The vacuum valve 1 has a rectangular, plate-shaped valve closure 4 (closing plate, valve disc) which has a sealing surface 6 for the gas-tight closure of an opening 2. The opening 2 has a cross-section corresponding to the valve closure 4 and is formed in a wall 8. The wall 8 can, for example, be the wall of a vacuum machining chamber. The opening 2 is surrounded by a valve seat, which in turn also provides a sealing surface 3 corresponding to the sealing surface 6 of the valve closure 4. The sealing surface 6 of the valve closure 4 surrounds the valve closure 4 and includes a sealing material (gasket). In a closed position S (Fig. 1c), the gasket is compressed between the sealing surfaces 6 and 3. The opening 2 connects a first gas region L, located to the left of wall 8, with a second gas region R to the right of wall 8. Wall 8 is formed, for example, by a chamber wall of a vacuum chamber. The vacuum valve 1 is then formed by an interaction between the chamber wall 8 and the valve closure 4. It is clear that the valve seat, together with the first sealing surface 3, can alternatively be formed as a valve component that is structurally fixed to the valve 1 and can, for example, be arranged at a chamber opening, for example, by being screwed on. At least both of these embodiments are covered by the present invention. The valve closure 4 can be arranged, as shown here, on an adjusting arm 5 (valve stem), which here, for example, is rod-shaped and extends along a geometric adjusting axis V. The adjusting arm 5 is mechanically coupled to a pneumatic drive unit 7, whereby the closure element 4 in the first gas area L to the left of the wall 8 can be adjusted by means of the drive unit 7 from an open position O (Fig. 1a) via an intermediate position Z (Fig. 1b) to a closed position S (Fig. 1c). In the open position O, the valve closure 4 is located outside a projection surface of the opening 2 and fully exposes it. By linearly moving the valve closure 4 in an axial direction in a plane parallel to or coaxial with the adjustment axis V and parallel to the wall 8, the valve closure 4 can be moved from the open position O to the intermediate position Z by means of the drive unit 7. In this intermediate position Z ( Fig. 1b) the sealing surface 6 of the valve closure 4 is located at a distance from the sealing surface 3 of the valve seat, which surrounds the opening 2. By adjusting in the direction of the opening axis A, which is defined by the opening 2 (here: perpendicular to the adjustment axis V), i.e. perpendicular to the wall 8 and the valve seat, the valve closure 4 can be adjusted from the intermediate position Z to the closed position S (Fig. 1c). In the closed position S, the valve disc 4 closes the opening 2 gas-tight and separates the first gas area L gas-tight from the second gas area R. The vacuum valve is opened and closed by means of the drive unit 7, in this case by an L-shaped movement in two directions V and A of the valve closure 4, which are, for example, perpendicular to each other. The valve shown is therefore also referred to as an L-type valve. A transfer valve 1, as shown, is typically used to seal a process volume (vacuum chamber) and to load and unload that volume. Frequent changes between the open position O and the closed position S are the norm in such an application. This can lead to increased wear of the sealing surfaces 6 and 3, the inserted seal, and the mechanically moving components. A prior art transfer valve of this type performs the opening and closing of the valve in two steps, i.e., moving the valve closure 4 along a first axis and then moving the valve closure 4 along a second axis perpendicular to the first axis. Due to the required sequential movement, the opening and closing periods of the valve are comparatively time-consuming. The structural design of transfer valve 1 provides a general motion profile; that is, acceleration, velocity, and sealing force are fixed. Consequently, these parameters are defined such that a closed state of the valve fulfills the sealing requirements of any application. This results in a high sealing force (the force with which the valve closure is pressed against the valve seat) that is sufficient even when the machining chamber is vented, e.g., for chamber cleaning processes. However, the sealing force required to close the valve during a typical machining operation under vacuum conditions could be significantly lower to still meet the corresponding machining requirements. Consequently, the sealing material is subjected to greater stress than necessary, and the service life of the seal is correspondingly reduced. Fig. 2 shows a movement profile of the vacuum valve according to Fig. 1. As described above, the drive mechanism of valve 1 is a two-axis (vertical-horizontal) motion mechanism in which the actuation of the valve closure 4 is to be carried out sequentially, which in particular includes a defined delay for each axis (due to the lack of position information) to ensure correct valve opening and closing, which in turn causes a long actuation time. This sequential actuation is shown for a closing process, i.e., changing the valve state from the open position O to the closed position S. First, the valve stem 4 is moved along the adjustment axis V, which corresponds to changing the y-position of the stem 4. Once the extended state of the valve stem 5 is reached, i.e., when the valve stem 5 is in the intermediate position Z, the valve stem 4 is moved along the opening axis A perpendicular to the adjustment axis V until the valve is closed. This second part of the movement along the opening axis A corresponds to a change in the x-position, as shown. Figs. 3a-3c show an embodiment of a vacuum transfer valve 1 according to the invention in different closing positions. This embodiment differs from the embodiment of Fig. 1 by a different drive unit 10. The drive unit 10 comprises a first pneumatic actuator 11 coupled to the valve stem 5, which is configured here as a valve rod. The drive unit 10 is configured to provide movement of the closure plate 4 in a first (longitudinal) direction. The first direction corresponds to an extension of the adjustment axis V, i.e., a movement of the valve stem 5 along the adjustment axis V. The first pneumatic actuator 11 is connected to a first fluid flow controller 12, which is arranged and configured to provide a defined actuating fluid flow to or from the first pneumatic actuator 11. Furthermore, a first pressure sensor 13 is arranged and configured to measure a first actuation pressure in the first pneumatic actuator 11, i.e., a pressure exerted on the first pneumatic actuator 11. The first pneumatic actuator 11 includes a return element (not shown), e.g. a spring, which provides a return force against an actuating force exerted on the valve rod 5 by pressurizing the first pneumatic actuator 11. In an alternative embodiment (not shown), the first pneumatic actuator 11 can include a further fluid flow controller connected to the actuator 11 to provide pressure to an opposite side of a movement element 17 inside the actuator 11. This allows counter-movement of the valve closure in the opposite direction to be provided and controlled. The drive unit 10 also includes a second pneumatic actuator 12, which is coupled to the valve stem 5 and configured to provide movement of the closure plate 4 in a second (longitudinal) direction. The second direction is orthogonal to the first direction. Here, the second direction corresponds to an extension of the opening axis A in the closed state S of the valve or is parallel to the opening axis A. The second pneumatic actuator 14 is connected to a second fluid flow controller 15, which is arranged and configured to provide a defined actuating fluid flow to or from the second pneumatic actuator 14. Furthermore, a second pressure sensor 16 is arranged and configured to measure a first actuation pressure in the second pneumatic actuator 14, i.e., a pressure exerted on the second pneumatic actuator 14. The second pneumatic actuator 14 may include a spring or an additional fluid flow regulator, as described above for the first actuator, to provide (and control) a counter-movement of the valve plate, i.e. in one direction opposite to the second direction. The vacuum transfer valve 1 also includes a control unit 20. The control unit 20 is connected to the first fluid flow controller 12 and the second fluid flow controller 15 to control fluid flow through the flow controllers, and is connected to the first pressure sensor 13 and the second pressure sensor 16 to receive pressure information relating to the pressures in the actuators 11 and 14. The control unit 20 is set up to provide movement of the closure plate 4 according to a movement profile by controlling the first fluid flow controller 12 and the second fluid flow controller 15 depending on pressure information provided by the first pressure sensor 13 and the second pressure sensor 16. The control unit 20 is configured to control the first fluid flow controller 12 and the second fluid flow controller, such that the motion profile includes simultaneous movement of the closure plate 4 in the first direction and in the second direction. In other words, the first and second pneumatic actuators are pressurized at least partially simultaneously. Consequently, a change in the valve state or the state of the valve closure 4 from an open state O to a closed state (or vice versa) can be achieved in significantly less time. This is because closing the valve does not require two separate movements; instead, a smooth and homogeneous movement of the closure 4 is provided. Such smooth movement further reduces particle generation and vibration due to the gentle opening and closing. The control unit 20 is further configured to process the pressure information in order to detect individual positions (e.g., closed position) of the valve closure 4. This enables real-time tracking of the valve closure 4. Based on this, the pressure profile can be adjusted to minimize vibration and particle generation, in addition to simultaneous actuation of other axes and a reduction in overall actuation time. In particular, a digital model, e.g., a digital twin, of the vacuum transfer valve 1 is provided. The digital model provides a description or determination of valve states depending on the (measured) pressure information. In other words, knowledge of the pressure in a pneumatic actuator makes it possible, for example, to derive the position of the valve closure 4. The control unit 20 can be configured to derive a first control signal for controlling the first fluid flow controller and a second control signal for controlling the second fluid flow controller based on the digital model and the pressure information. Additionally, motion or position control of the pneumatic cylinders can be achieved using only the digital twin or models, without the need for real-time position measurement or an indicator. This allows for open-loop control without the need for a sensor. To adjust the digital twin so that it best matches real-world conditions, environmental information such as temperature or humidity, friction, or other environmental conditions can be derived (e.g., measured or simulated) to adjust the model parameters or motion parameters accordingly. Based on the digital model and pressure information, the progression of the valve state during movement of the closure plate 4 can be monitored. This allows for the detection of any associated early pressure increase if the movement path of the lock (valve closure) is blocked, for example, by an obstacle. Combined with a digital twin that references the actual position, undesirable states of the transfer valve can be deduced. Furthermore, the monitored progression of the valve state can be compared with reference valve states that relate to the movement profile of the sealing plate, and valve operating information can be derived based on such a comparison. The digital model can also be used for predictive valve maintenance. This involves deriving long-term trends in valve states or achieved movement profiles based on pressure measurements and processing of these pressures with the digital model. Such model-based processing can be performed over a number of processing cycles or a specific time period. The processing results can be compared with each other or with a reference value to determine the trend. Based on this trend, valve maintenance can be planned accordingly. Since the pneumatic actuators can be individually controlled, the movement of the sealing plate 4 can be optimized for a specific application to be provided by the valve. Such applications might include, for example, venting the machining chamber or a typical machining step within the chamber. In the case of venting the machining chamber, the force required to press the valve seal 4 against the valve seat 3 must be greater than the corresponding force required for machining. This is due to the significantly higher pressure differential between the first gas chamber L and the second gas chamber R during chamber venting. According to the invention, the pneumatic actuators 11, 14 are controllable by means of their fluid flow controllers 12, 15, i.e., by adjusting the amount of fluid flowing into (or out of) the pneumatic actuator(s) 11, 14. The pressures in the actuators 11, 14 are directly dependent on the fluid flows. This means that the pressure in, for example, the pneumatic actuator 14 can be controlled and varied, and the (pressing) force for pressing the valve closure 4 against the valve seat 3 can likewise be adjusted. The motion profile for the pneumatic actuator 14 or for the pneumatic actuator 11 or for the general movement of the valve can each include pressure levels applied over time. Thus, the transfer valve 1 can be controlled differently according to an applied or desired application, e.g. by changing the motion profile or the control parameters that are processed to control the fluid flow controllers 12, 15. The control unit can therefore be configured to provide a set of motion profiles, each provided by superimposing a movement of the closure plate in the first direction and a movement of the closure plate in the second direction. At least two of the set of motion profiles can be individually selected to be tracked by the closure plate 4. In particular, the motion profiles relate to corresponding control parameters for controlling the fluid flow controllers 12, 15. Fig. 4 shows a movement profile of the vacuum valve according to the invention. As described above, the drive unit of a valve according to the invention is a simultaneous biaxial (vertical-horizontal) pneumatic actuator, where the actuation of the valve closure 4 is to be carried out in a single sequence, which in particular includes a superposition of movement in the x and y directions. This provides smooth movement of the valve closure 4 and a correspondingly gentle closing with shorter actuation times. This simultaneous actuation is shown for a closing process, i.e., changing the valve state from the open position O to the closed position S. The valve closure 4 is moved along the adjustment axis V, which corresponds to changing the y-position of the closure 4, and is also moved simultaneously in a direction parallel to or corresponding to the opening axis A, perpendicular to the adjustment axis V. The valve closure 4 essentially reaches its end position in the x- and y-directions simultaneously. In a preferred embodiment, the movement along the adjustment axis V (y-position) is completed before the movement in the orthogonal direction. Fig. 5a shows a pressure profile of a pneumatic actuator for controlling a movement to close the valve according to the invention. As can be seen, the pressure level begins to rise with a slight inclination. The pressure then rises more sharply to provide shorter actuation times. In a third phase of movement, as the valve closure approaches the valve seat, the pressure rise is again less pronounced to provide a gentle contact. Fig. 5b shows a corresponding movement profile of the valve closure 4 in the x-direction and in the y-direction, i.e. along the adjustment axis V and orthogonal to the axis V, over time, which is a result of applying the pressure profile according to Fig. 5a. The movement follows the pressure profile. This results in a fast but smooth movement of the valve closure, which also ensures a gentle closing of the valve. The force for pressing the valve closure 4 against the valve seat 3 can be adjusted, for example, by generally increasing the final pressure level, particularly with regard to the second pneumatic actuator 14. It is clear that the figures shown represent possible exemplary embodiments only schematically. The various methods according to the invention can also be combined with each other and with prior art methods and devices for controlling a pneumatic transfer valve. QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature US 6 629 682 B2 [0008, 0014]US 6 416 037

[0011] US 6 056 266

[0011] US 64 431 518 B1

[0014] US 5 415 376 A

[0014] US 5 641 149 A

[0014] US 6 045 117 A

[0014] US 5 934 646 A

[0014] US 5 755 255 A

[0014] US 6 082 706

[0014] US 6 095 180

[0014] US 5 769 952

[0015] US 2008 / 0083897 A1

[0015]

Claims

Vacuum transfer valve (1) with: • a valve wall (8) having an opening (2) and a valve seat (3) extending around the opening (2), • a sealing plate (4) with a sealing side for gas-tight closure of the opening (2), • an actuating unit (10) coupled to the sealing plate (4) by means of a valve rod (5) and configured such that the sealing plate (4) can be moved from: ▫ an open position (O), in which the sealing plate (4) releases the opening (2), to ▫ a closed position (C), in which the sealing side of the sealing plate (4) is pressed against the valve seat (3) and gas-tightly closes the opening (2), and ▫ back again, characterized in that the actuating unit (10) comprises: • a first pneumatic actuator (11) coupled to the valve rod (5) and configured to provide movement of the sealing plate (4) in a first direction, • a second pneumatic actuator (14)which is coupled to the valve stem (5) and is configured to provide movement of the closure plate (4) in a second direction, • a first pressure sensor (13) which is arranged and configured to measure a first actuating pressure in the first pneumatic actuator (11), • a second pressure sensor (16) which is arranged and configured to measure a second actuating pressure in the second pneumatic actuator (14), • a first fluid flow controller (12) which is arranged and configured to provide a defined actuating fluid flow to or from the first pneumatic actuator (11), and • a second fluid flow controller (15) which is arranged and configured to provide a defined actuating fluid flow to or from the second pneumatic actuator (14). Vacuum transfer valve (1) according to claim 1, wherein the second pneumatic actuator (14) is coupled to the valve rod (5) and to the sealing plate (4). Vacuum transfer valve (1) according to claim 1 or 2, wherein the second pneumatic actuator (14) is coupled to the valve rod (5) and the sealing plate (4) and provides mobility of the sealing plate (4) relative to the valve rod (5). Vacuum transfer valve (1) according to one of the preceding claims, wherein the vacuum transfer valve (1) comprises a control unit (20) which is configured to provide movement of the closure plate (4) according to a movement profile by controlling the first fluid flow controller (12) and the second fluid flow controller (15). Vacuum transfer valve (1) according to claim 4, wherein the control unit (20) is configured to control the first fluid flow controller (12) and the second fluid flow controller (15) depending on pressure information provided by the first pressure sensor (13) and the second pressure sensor (16). Vacuum transfer valve (1) according to claim 4 or 5, wherein control of the first fluid flow controller (12) and the second fluid flow controller (15) is provided such that the movement of the closure plate (4) includes simultaneous movement in the first direction and in the second direction. Vacuum transfer valve (1) according to one of claims 4 to 6, wherein a first pressure profile is provided to control the first fluid flow controller and a second pressure profile is provided to control the second fluid flow controller. Vacuum transfer valve (1) according to one of claims 4 to 7, wherein the control unit (20) is configured to provide a set of motion profiles, each of which provides a superposition of a movement of the closure plate (4) in the first direction and a movement of the closure plate (4) in the second direction, wherein at least two of the set of motion profiles are individually selectable to be tracked by the closure plate (4). Vacuum transfer valve (1) according to one of claims 4 to 8, wherein the control unit (20) comprises a motion profile planner which, when executing, generates or sets the motion profile by adjusting the control, provides at least one of the first fluid flow controller (12) and the second fluid flow controller (15). Vacuum transfer valve (1) according to claim 9, wherein the motion profile planner comprises non-adjustable basic conditions to provide valve integrity when the vacuum transfer valve (1) is driven with a generated or set motion profile, wherein the basic conditions comprise at least one of: • a motion offset with respect to the extent of a movement of the sealing plate (4) in the first direction relative to the second direction, • a speed limit of a movement of the sealing plate (4), • a limit of the rate of change of a pressure of the actuating fluid, in particular a limit of an acceleration of the sealing plate (4), and • a limit with respect to pressing of the sealing plate (4) against the valve seat (3). Vacuum transfer valve (1) according to any one of claims 4 to 10, wherein • a digital model of the vacuum transfer valve is provided, wherein the digital model provides a description or determination of valve states depending on the pressure information, and • the control unit is configured to derive a first control signal to control the first fluid flow controller and a second control signal to control the second fluid flow controller, based on the digital model and the pressure information. Vacuum transfer valve (1) according to claim 11, wherein the control unit (20) is configured to derive a position of the closure plate (4) depending on the pressure information based on the digital model. Vacuum transfer valve (1) according to claim 9 or 12, wherein • the vacuum transfer valve (1) comprises an environmental condition sensor for measuring an environmental parameter and • the control unit (20) is configured to process the environmental parameter during the provision of the description or determination of valve states. Vacuum transfer valve (1) according to one of claims 9 to 13, wherein the control unit (20) is configured to: • monitor the progression of the valve state during movement of the closure plate (4) based on the digital model and the pressure information, • compare the monitored progression of the valve state with reference valve states relating to the movement profile of the closure plate (4), and • derive valve operating information based on the comparison. Vacuum transfer valve (1) according to one of claims 4 to 14, wherein the control unit (20) is configured to: • determine a long-term trend based on monitoring the progression of the valve state for several control cycles, • derive valve state information based on the long-term trend, • compare the valve state information with a predefined threshold, and • generate maintenance information based on the comparison.

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