Method for operating a pneumatic system and pneumatic system for industrial automation

Abstract

The invention relates to a method for operating a pneumatic system, which has at least one pneumatic actuator (3) and a control device (2) for controlling a movement of an actuator element (15) of the at least one pneumatic actuator (3) from a first position into a second position and / or from the second position into the first position, comprising the following steps: measuring an actual mass flow of pressurized fluid supplied to and / or discharged from the pneumatic actuator (3), providing a mass flow signal to the control device (2), measuring an actual pressure in a pressure chamber (20, 21, 34, 35) of the pneumatic actuator (3), providing the actual pressure as an actual pressure signal to the control device (2), determining an estimated pressure value in a pressure chamber (20, 21, 34, 35) of the pneumatic actuator (3), comparing the actual pressure signal with the estimated pressure value, providing a deviation characteristic value on the basis of the comparison between the actual pressure signal and the estimated pressure value, determining position information of an actuator element (15) of the pneumatic actuator (3) on the basis of the mass flow signal and the actual pressure signal and / or the estimated pressure value as well as a pneumatic system (1) for industrial automation.

Description

[0001] Method for operating a pneumatic system and pneumatic system for industrial automation

[0002] The invention relates to a method for operating a pneumatic system for industrial automation and a pneumatic system for industrial automation.

[0003] Methods for operating pneumatic systems for industrial automation, as well as pneumatic systems for industrial automation, are now used in many areas. In particular, pneumatic systems are used in wafer processing plants, where the slide valves, actuated by pneumatic actuators, serve primarily to open or close a processing chamber opening for wafers, through which a wafer can be inserted. The pneumatic actuators of the system can also be used to drive a positioning structure for the wafers within the processing chamber.

[0004] The purpose of the present invention is to provide an improved method for operating a pneumatic system.

[0005] The foregoing problem is solved by a method for operating a pneumatic system for industrial automation, comprising at least one pneumatic actuator and a control device for controlling the movement of an actuator element of the at least one pneumatic actuator from a first position to a second position and / or from the second position to the first position, comprising the steps of: measuring a mass flow rate of pressurized fluid supplied to and / or discharged from the pneumatic actuator, providing a mass flow rate signal to the control device, measuring a pressure in a pressure chamber of the pneumatic actuator, providing the pressure as a pressure signal to the control device, determining a pressure estimate in a pressure chamber of the pneumatic actuator, and comparing the pressure signal with the pressure estimate.Providing a deviation parameter based on the comparison between the actual pressure signal and the estimated pressure value, and determining position information of an actuator element of the pneumatic actuator based on the mass flow signal and the actual pressure signal and / or the estimated pressure value.

[0006] For the purposes of this application, "position" is understood to mean any position of the pneumatic actuator, such that a movement from the first position to the second position and / or from the first position to the second position may be a complete movement to a first end position and / or second end position, or a partial movement in which the pneumatic actuator is moved to any position between the end positions.

[0007] In the method implemented on the control device, a mass flow of pressurized fluid, preferably compressed air, is first supplied to and / or discharged from the pneumatic actuator in order to move the actuator element of the pneumatic actuator from a first position to a second position and / or from the second position to the first position. The supplied and / or discharged mass flow is measured so that the actual mass flow supplied to and / or discharged from the pneumatic actuator is known. This actual mass flow is provided as a mass flow signal to the control device.

[0008] The pressure profile in the pneumatic actuator, resulting from the incoming and / or outgoing mass flow rate (Ist), can be described using a differential equation based on the ideal gas law. Accordingly, the pressure profile can be calculated from the provided mass flow rate signal using this relationship. The position and velocity of the actuator element also influence the pressure profile and are therefore required as input variables for the calculation. To simplify the calculation, a constant temperature of the pressurized fluid can be assumed during movement.

[0009] If the actuator element, for example, has a working piston that is arranged in a working chamber of the pneumatic actuator, which is formed in a cylinder housing of the pneumatic actuator, such that it defines at least one pressure chamber, and if a mass flow of pressurized fluid is supplied to or discharged from this pressure chamber, then the pressure profile within this pressure chamber is a measure of the actuator element's position. Accordingly, position information of the actuator element, particularly in real time, can be determined based on the mass flow rate (Ist), which is provided as a mass flow signal to the control device. For this purpose, it is necessary to first provide an estimated position and an estimated velocity of the actuator element as further input variables for the differential equation.These quantities are initially estimated using a suitable assumption, where, for example, zero or a suitable non-zero starting value can be assumed. Subsequently, a pressure estimate is calculated, particularly in real time, based on the measured mass flow rate and the assumptions for position and velocity. Using the relationship described above, the pressure prevailing in the pressure chamber of the pneumatic actuator can be calculated based on the actual mass flow rate in the chamber, using the estimated position and velocity for the calculation. Consequently, the calculated pressure is a pressure estimate whose accuracy, i.e., the deviation from the actual pressure, depends on the accuracy of the estimated position and velocity.

[0010] Simultaneously, the actual pressure is measured and provided to the control unit as an actual pressure signal. This actual pressure signal is then compared with the estimated pressure value, particularly in real time. Based on this comparison, a deviation parameter is provided, also in real time. This parameter measures the accuracy of the estimated pressure value and is calculated as the difference between the estimated pressure value and the actual pressure signal. A large deviation, and thus a large deviation parameter, also indicates a large discrepancy between the actual speed and the actual position of the piston.Subsequently, particularly in real time, the acceleration of the piston in a model, and through time integration the estimated velocity, and through double time integration or time integration from the estimated velocity the estimated position, are varied and used as new assumptions for the position and the velocity until the pressure estimate corresponds to the actual pressure signal or has approximated it sufficiently closely, and thus the estimated velocity corresponds to the real velocity and the estimated position to the real position.

[0011] No further input variables are required, so the position of the actuator can be determined based on the mass flow signal and the actual pressure signal and / or the estimated pressure value. This advantageously eliminates the need for position monitoring throughout the entire movement of the actuator.

[0012] The control device preferably comprises a controller, in particular a real-time capable controller, and at least one valve, preferably a proportional valve and more preferably a piezo proportional valve, wherein a piezo proportional valve is used particularly in applications requiring high control accuracy. The controller and the at least one valve can be arranged in a common housing or in separate housings, wherein, in the case of separate housings, a suitable signal connection exists between the controller and the at least one valve, in particular a real-time capable signal connection.

[0013] Advantageous further developments of the invention are the subject of the dependent claims.

[0014] In a further development of the method, this also includes the step of varying the actual mass flow supplied and / or discharged to the pneumatic actuator to minimize the deviation parameter, preferably to minimize a deviation between a target position, i.e., a required position of the pneumatic actuator, and the estimated position, and / or between a target speed, i.e., a required speed of the actuator, and the estimated speed.

[0015] By means of a control system, the actual mass flow rate supplied and / or discharged is varied in order to minimize the deviation parameter, i.e., until the calculated pressure estimate corresponds to the actual pressure signal signal and / or until the estimated position corresponds to a target position and / or the estimated speed corresponds to a target speed.

[0016] Preferably, the method further comprises the step of varying the mass flow rate supplied to and / or discharged to the pneumatic actuator to adjust the acceleration of the actuator element based on an estimated position and / or an estimated velocity and / or the Ist pressure and / or the estimated pressure value. By varying the mass flow rate, the acceleration of the actuator can be adjusted based on the estimated position and / or the estimated velocity and / or the Ist pressure and / or the estimated pressure value, each of which serves as an input to the differential equation defined above, thereby minimizing, in particular, the deviation parameter or, in each case, a deviation between an estimated quantity and a target quantity and / or a real quantity.

[0017] Advantageously, the method further comprises the following steps: continuously measuring the position of the pneumatic actuator element as it moves into the first end position and / or the second end position; providing the measured position as an actual position signal to the control unit; and varying the mass flow supplied to and / or discharged to the pneumatic actuator to adjust the acceleration of the actuator element based on the measured position and / or the velocity and / or the actual pressure and / or the estimated pressure value. Upon reaching the first end position and / or the second end position, a shock resulting from an abrupt stop of the movement, for example, upon contact of the actuator element with a mechanical stop, should be prevented. Accordingly, the movement of the actuator element should be slowed down shortly before reaching the end position.By additionally providing a measured position in the area of ​​the end positions, the control system is enabled to additionally consider the actual position signal in order to further improve the accuracy of the determination of the position information.

[0018] For the purposes of this application, continuous measurement is understood to mean value- and / or time-continuous as well as value- and / or time-discrete measurement.

[0019] Preferably, the method can be used to operate a pneumatic system comprising a slide valve, wherein the slide valve has a valve element that is connected to the actuator element of the pneumatic actuator and is moved along with the actuator element, and wherein the slide valve has an opening for the passage of a wafer, which can be opened or closed by the valve element.

[0020] Preferably, the pneumatic actuator is a single-acting or double-acting pneumatic cylinder, and the actuator element comprises a drive piston and a piston rod. The single-acting or double-acting pneumatic cylinder has a cylinder housing with a working chamber formed therein, in which the drive piston of the actuator element is movably arranged. The piston rod is coupled to the drive piston, partially penetrates the cylinder housing, and is movably mounted within it. In the case of a single-acting pneumatic cylinder, the drive piston, together with the cylinder housing, defines a pressure chamber into which pressurized fluid can be supplied or discharged to move the drive piston. A return element, in particular a spring, may be provided between a housing wall of the cylinder housing and the drive piston to reverse the movement.In the case of a double-acting cylinder, the drive piston defines a first pressure chamber and a second pressure chamber, to which pressure fluid can be supplied or discharged, depending on the desired direction of movement of the drive piston.

[0021] The method can preferably be used to operate a pneumatic system comprising a plurality of pneumatic actuators, where the movement from a first position to a second position and / or from the second position to the first position is controlled by the control device. The inventive method enables individual control of each of the plurality of pneumatic actuators. Individual control means that the control device executes the previously described procedure independently for each of the pneumatic actuators, and synchronization between the movements of the respective actuator elements is also possible. Furthermore, timing coordination of the movements of the individual actuator elements of the plurality of pneumatic actuators is possible.

[0022] The previously outlined task is also solved by a pneumatic system for industrial automation, comprising: at least one pneumatic actuator with an actuator element, a control device for controlling a movement of the actuator element from a first position to a second position and / or from the second position to the first position, and a mass flow measuring unit for measuring a mass flow of pressurized fluid supplied to and / or discharged from the pneumatic actuator and for transmitting the measured mass flow as a mass flow signal to the control device.

[0023] Preferably, the pneumatic system further comprises at least one pressure measuring unit for measuring an I st pressure in at least one pressure chamber of the pneumatic actuator and transmitting the I st pressure to the control device.

[0024] Advantageously, the pneumatic system includes at least one position measuring unit for the continuous measurement of the actual position of the actuator element of the pneumatic actuator when moving into a first end position and / or into a second end position and for transmitting the actual position to the control device.

[0025] Preferably, the pneumatic system comprises a slide valve, wherein the slide valve has a valve element which has an actuator element and an opening for the passage of a wafer that can be closed by the valve element, and wherein the pneumatic actuator serves to actuate the slide valve.

[0026] The slide valve can have a valve housing in which an opening is formed in a first valve housing wall and a further opening in a second valve housing wall for the passage of a wafer. The opening in the first valve housing wall can be closed by a valve element movable relative to the valve housing. The opening and the further opening are preferably configured to correspond, such that the extent of the further opening corresponds in the vertical, transverse, and width directions to the extent of the opening in the vertical, transverse, and width directions. The respective extent is selected such that the wafer can pass through the opening and the further opening. Additionally, the further opening is arranged facing away from the opening, so that a wafer can be transported from the processing room and / or into the processing room.In a deactivated position, the opening in the first valve body wall of the slide valve is not closed by the valve element, while in an activated position, the opening in the first valve body wall of the slide valve is closed by the valve element. Accordingly, in this context, the deactivated position can also be referred to as the closed position of the valve element and the activated position as the open position of the valve element.

[0027] The valve housing of the slide valve can also consist of only the first valve housing wall with an opening formed therein, which can be closed by the valve element movable relative to the valve housing. The valve element can preferably be movably guided by means of a guide unit formed on the valve housing.

[0028] To ensure the tightest possible closure of the opening, the valve element can have a circumferential, in particular rubber-elastic, sealing element on its side facing the opening.

[0029] Preferably, the pneumatic system comprises a plurality of pneumatic actuators. For example, the pneumatic system can be implemented as a wafer processing system, consisting, for instance, of a distribution room and several processing rooms, with the processing rooms adjoining the distribution room. Each processing room can be isolated from the distribution room by a slide valve, for which at least one pneumatic actuator is provided. The distribution room itself can also be isolated from the environment by a slide valve, for which a pneumatic actuator is provided.

[0030] Preferably, a first pneumatic actuator of the plurality of pneumatic actuators and a second pneumatic actuator of the plurality of pneumatic actuators are used to actuate the slide valve, wherein the first pneumatic actuator is rotatably mounted and is configured for a displacement of the valve element along a direction of movement, and the second pneumatic actuator is motion-coupled with the first pneumatic actuator to set the first pneumatic actuator into a tilting movement.For example, it can be made possible that, in order to close the opening of the slide valve, the valve element of the slide valve is first brought from a deactivated position to a partially activated position by moving the actuator element of the first pneumatic actuator from a first end position to a second end position and subsequently the valve element is moved from the partially activated position to the activated position by a tilting movement of the first pneumatic actuator, wherein the tilting movement is carried out by the movement of the actuator element of the second pneumatic actuator from the first end position to the second end position.

[0031] It is also possible for the second pneumatic actuator to be attached to the actuator element, specifically the piston rod, of the first pneumatic cylinder, and for the piston rod of the second pneumatic actuator to be motionally coupled to the valve element. Accordingly, the valve element can be moved from the partially activated position to the activated position by moving the actuator element of the second pneumatic actuator. A rotatable mounting of the first pneumatic actuator is not required in this configuration.

[0032] The invention is explained in more detail below using the attached drawing, and shown in this drawing.

[0033] Figure 1 shows a schematic representation of a pneumatic system implemented as an example wafer processing cell.

[0034] Figure 2 shows a block diagram of an inventive method for operating a pneumatic system for industrial automation.

[0035] Figure 3 shows a schematic representation of a pneumatic system designed as a wafer processing system.

[0036] Figure 4 shows a schematic representation of a first embodiment of a slide valve in a deactivated fourth position and in an activated position and

[0037] Figure 5 shows a schematic representation of a second embodiment of a slide valve in a deactivated fourth position, in a partially activated position and in an activated position.

[0038] Figure 1 shows an exemplary embodiment of a pneumatic system 1 for industrial automation, implemented as a wafer processing cell, with which the inventive method can be carried out. The pneumatic system comprises a control device 2, a pneumatic actuator 3, a slide valve 4, and a processing chamber 5. For illustrative purposes only, only one pneumatic actuator 3 is shown. However, it is also possible for multiple pneumatic actuators 3 to be present.

[0039] It is also possible that the inventive pneumatic system 1 will be used for other applications in industrial automation.

[0040] The processing chamber 5, in which a pressure below atmospheric pressure prevails, has, by way of example, an essentially rectangular shape and extends in a vertical direction, which can also be referred to as the y-direction, in a transverse direction perpendicular to the vertical direction, which can also be referred to as the x-direction, and in a lateral direction, which can also be referred to as the z-direction and is oriented perpendicular to both the vertical and transverse directions. The processing chamber 5 has a processing chamber opening 6, which can be closed by means of the slide valve 4 to seal the processing chamber 5 from the environment. The slide valve 4 has, by way of example only, a valve body 7 in which an opening 8 and a further opening 9 for the passage of a wafer (not shown) are formed, and a valve element 10 movable relative to the valve body 7.The opening 8 is formed in a first valve housing wall 11 and the further opening 9 is formed in a second valve housing wall 12, wherein the first valve housing wall 11 and the second valve housing wall 12 are spaced apart from each other in the transverse direction.

[0041] The opening 8 has, by way of example, a substantially rectangular cross-section, with its height and transverse dimensions chosen to allow the passage of the wafer. The further opening 9 is designed to correspond with the opening 8 such that its height, transverse, and width dimensions correspond to those of the opening 8. Additionally, the further opening 9 is arranged parallel to the opening 8, so that the wafer can pass through both the further opening 9 and the opening 8 even if the wafer's length is greater than the transverse distance between the first valve housing wall 11 and the second valve housing wall 12.The slide valve 4 borders the first valve housing wall 11 on the processing chamber 5 in such a way that the opening 8 overlaps the processing chamber opening 6 at least partially for the passage of the wafer.

[0042] The opening 8 and / or the second opening 9 may also have a cross-section that deviates from a substantially rectangular cross-section. Furthermore, it is possible that the valve housing 7 only has the first valve housing wall 11, in which the opening 8 is formed and which can be closed by the valve element 10.

[0043] The valve element 10 is arranged, by way of example, between the first valve housing wall 11 and the second valve housing wall 12 of the valve housing 7. The opening 8 can be closed by the valve element 10. To ensure the tightest possible closure of the opening 8, the valve element 10 has a circumferential, in particular rubber-elastic, sealing element 13 on its side facing the opening 8.

[0044] In the illustrated activated position of the slide valve 4, the opening 8 for the passage of the wafer through the valve element 10 is closed. In this context, a deactivated position is understood to be a position of the slide valve 4 in which the opening 8 is not closed by the valve element 10, thus allowing the passage of the wafer. In the illustrated embodiment, the pneumatic actuator 3, which can also be referred to as the valve actuator 14, is used to actuate the slide valve 4.

[0045] To enable an initial displacement of the valve element 10 along the vertical direction, the valve element 10 is connected to an actuator element 15 of the pneumatic actuator 3, which in this example comprises a first drive piston 16 and a first piston rod 17. Accordingly, the valve element 10 moves with the actuator element 15 to close or open the opening 8. For example, the opening 8 is closed by the valve element 10 when the actuator element 15 is in a second end position. When the actuator element 15 is in a first end position, the opening 8 is open, i.e., not closed by the valve element 10.

[0046] The pressure force required to close the opening 8, acting on the sealing element 13, is provided by the pressure difference, i.e., the difference between the pressure prevailing in the processing chamber 5 and the ambient pressure, via the slide valve 4.

[0047] The pneumatic actuator 3 of the exemplary embodiment shown is designed as a double-acting pneumatic cylinder comprising a cylinder housing 18, which defines a working chamber 19, and the valve actuator 14. The working chamber 19 is divided by the first drive piston 16 into a first pressure chamber 20 and a second pressure chamber 21. For the movement of the actuator element 15, a mass flow of pressurized fluid can be supplied to the first pressure chamber 20 and simultaneously discharged from the second pressure chamber 21. For a reversal of this movement, a mass flow of pressurized fluid is supplied to the second pressure chamber 21 and discharged from the first pressure chamber 20.

[0048] However, an embodiment is also conceivable in which a return element, in particular a return spring, is arranged within the first pressure chamber 20 or within the second pressure chamber 21 for the movement into the first end position or the second end position, and the pneumatic actuator 3 is accordingly designed as a single-acting pneumatic cylinder. If the return element is located, for example, in the second pressure chamber 21, it is arranged in this chamber such that when a mass flow of pressurized fluid is supplied into the first pressure chamber 20 by the first drive piston 16, it is compressed and, for the reversal of the movement, is relaxed and displaces the drive piston 16.

[0049] The control device 2 is configured to control the movement of the actuator element 15 from the first end position to the second end position and / or from the first end position to the second end position. For this purpose, the control device 2 can adjust the mass flow rate of pressurized fluid supplied to and / or discharged from the first pressure chamber 20 and / or the second pressure chamber 21 to enable a desired movement sequence. In pneumatic systems 1, it is particularly desirable to enable the fastest possible movement of the actuator element 15 in order to reduce the overall process duration or, especially in the exemplary wafer processing cell shown, to prevent a loss of negative pressure in the processing chamber 5 and / or contamination of the processing chamber 5 with ambient air.However, since no vibrations should occur when the first end position and / or the second end position is reached, the movement of the actuator element 15 must be slowed down shortly before and upon reaching the first and second end positions. Accordingly, the control device 2 can vary the mass flow of pressurized fluid supplied to and / or discharged from the first pressure chamber 20 and / or the second pressure chamber 21 of the pneumatic actuator 3. For this purpose, the control device 2 is fluidically connected to the first pressure chamber 20 and the second pressure chamber 21, each via a fluid line 22.To determine the precise mass flow rate of pressurized fluid supplied to and / or discharged from the first pressure chamber 20 and / or the second pressure chamber 21, a mass flow measuring unit 23 is arranged in the region of the first pressure chamber 20 and in the region of the second pressure chamber, wherein preferably no fluid line 22 is provided between the pneumatic actuator 3 and the respective mass flow measuring unit 23, so that the respective mass flow measuring unit 23 is fluidically directly connected to the pneumatic actuator 3. The mass flow measuring units 23 are designed as bidirectional mass flow measuring units 23, so that they can measure an supplied and discharged mass flow rate. The mass flow measuring units 23 provide a mass flow signal m corresponding to the mass flow rate Ist and transmit this to the control unit 2.For the transmission of the mass flow signal m to the control unit 2, the mass flow measuring units 23 are, purely by way of example, connected to the control unit 2 by means of signal lines 24. However, it can also be provided that the signal connection is implemented as a wireless signal connection.

[0050] In addition to the respective mass flow measuring units 23, a pressure measuring unit 25 is arranged in each of the first pressure chamber 20 and the second pressure chamber 21. This unit measures the static pressure, which can also be referred to as the static pressure (Ist), within the first pressure chamber 20 and the second pressure chamber 21, and transmits an Ist pressure signal corresponding to the Ist pressure in the first pressure chamber 20 and an Ist pressure signal corresponding to the Ist pressure in the second pressure chamber 21 to the control unit 2. In the illustrated embodiment, the Ist pressure signal is transmitted from the pressure measuring units 25 to the control unit 2 via signal lines 24. Alternatively, a signal connection between the pressure measuring units 25 and the control unit 2 can be implemented using a wireless signal connection.

[0051] The pneumatic actuator 3 of the embodiment of the pneumatic system 1 shown in Figure 1 has, purely by way of example, a position measuring unit 26 in the region of the first end position and in the region of the second end position of the actuator element 15 for continuous measurement of an actual position x of the actuator element 15 as it moves into the first end position and / or the second end position. In principle, continuous measurement of the actual position is not required for controlling the movement of the actuator element 15 by the control device 2. The measured actual position is provided as a position signal x to the control device 2, for which the position measuring units 26 are connected to the control device 2 via signal lines 24. A wireless signal connection can also be provided.

[0052] The control of the movement of actuator 15 from the first end position to the second end position and / or from the second end position to the first end position is to be carried out using the block diagram shown in Figure 2. For the sake of example, it is assumed that in the following description, actuator 15 is to be moved from the first end position to the second end position. The explanations apply analogously to the case where actuator 15 is to be moved from the second end position to the first end position.

[0053] The mass flow rate Ist, measured by the mass flow meter 23 and supplied to the first pressure chamber 20 for the movement of the actuator 15, is provided as an input signal to the method implemented on the control unit 2 for operating a pneumatic system. The pressure profile in the first pressure chamber 20 can be described using a differential equation based on the ideal gas law, starting from the mass flow signal. Thus, the pressure profile in the first pressure chamber 20 is described as a function of the mass flow rate m supplied to the first pressure chamber 20, the position of the actuator 15, and the velocity of the actuator 15. The position of the actuator 15 is a measure of the volume of the first pressure chamber 20, and the velocity of the actuator 15 is a measure of the change in volume.Based on the mass flow signal, position information for the actuator 15 is determined by calculating the corresponding pressure within the first pressure chamber 20 for the received mass flow signal. For the calculation, an estimated position xs and an estimated velocity vs of the actuator 15 are initially assumed, so the calculated pressure can also be referred to as the pressure estimate ps. Alternatively, initial values ​​for the position and velocity of the actuator 15 as a function of the mass flow signal can be used in a table, which is stored, for example, on a programmable memory unit (not shown) of the control device 2.The estimated pressure ps is then compared with the actual pressure (Ist) measured by the pressure measuring unit 25, which is fluidically connected to the first pressure chamber 20. The pressure signal generated by the pressure measuring unit 25 is transmitted to the control unit 2 as the Ist pressure signal. Based on the comparison between the Ist pressure signal and the estimated pressure ps, a deviation parameter e can be defined, which results from the difference between the Ist pressure signal and the estimated pressure ps. The deviation parameter e is therefore a measure of the deviation between the actual pressure in the first pressure chamber 20 and the estimated pressure ps. The deviation parameter e is then transmitted to the control unit 2 as a further input.The deviation parameter is used as a further parameter for calculating the pressure estimate ps, and the control unit 2 varies the acceleration, and thus the estimated velocity vs and the estimated position xs of the actuator 15, in order to minimize the deviation parameter e. This occurs until the pressure estimate ps corresponds to the actual pressure signal. At this point, the estimated velocity vs corresponds to the actual velocity of the actuator 15, and the estimated position xs corresponds to the actual position of the actuator 15.

[0054] When the actuator element 15 moves into the first end position, its position is measured by the corresponding position measuring unit 26 and provided to the control unit 2 as the actual position signal x. Accordingly, the control unit 2 can take the position of the actuator element 15 into account in this range when varying the mass flow supplied to the first pressure chamber 20, in order to adjust the acceleration of the actuator element 15. This prevents the actuator element 15 from moving into the end position at an excessively high speed. Figure 3 shows a pneumatic system 1 designed as a wafer processing system with several processing chambers 5 and several pneumatic actuators (not shown). The processing chambers 5 are arranged around a distribution chamber 27, with each of the several processing chambers 5 being able to be shut off from the distribution chamber 27 by a slide valve 4.The distribution chamber 27 can also be shut off from the environment by means of a slide valve 4. Furthermore, the pneumatic system 1 includes a control unit 2. Each of the slide valves 4 is fluidically connected to the control unit 2 via a fluid line 22. The mass flow rate (Ist) supplied to and / or discharged from the first or second pressure chamber of the respective pneumatic actuator (not shown) is measured by means of mass flow measuring units (not shown) and provided to the control unit 2 as a mass flow signal. Furthermore, the pressure (Ist) in the first and / or second pressure chamber of the respective pneumatic actuator is measured by means of corresponding pressure measuring units (not shown) and provided to the control unit 2 as a pressure signal (Ist).

[0055] The control device 2 is designed to regulate the movement of the individual actuator elements of the pneumatic actuators not shown, as described above.

[0056] Figure 4 shows a first embodiment of the slide valve 5, as depicted in Figure 1, in a deactivated position (left) and an activated position (right), wherein in the deactivated position the opening 8 in the first valve housing wall 11 of the slide valve 5 is not closed by the valve element 10 and in the activated position the opening 8 in the first valve housing wall 11 of the slide valve 5 is closed by the valve element 10.In the illustrated embodiment, the valve element 10 rests against the first valve housing wall 11 with the circumferential, in particular rubber-elastic, sealing element 13 arranged on its side facing the opening 8, so that in the active position the sealing force used for sealing, acting on the sealing element 13, is applied by a pressure difference between the pressure prevailing in the space to be shut off, in particular the processing chamber 5 or the distributor chamber 27, and the ambient pressure, wherein the pressure in the space to be shut off is below the ambient pressure.

[0057] In the illustrated embodiment, a pneumatic actuator 3 designed as a double-acting pneumatic cylinder is used to actuate the slide valve 5, the first piston rod 17 of which is coupled to the valve element 10 in terms of movement and enables the displacement of the valve element 10 along the vertical direction.

[0058] Figure 5 shows a second embodiment of a slide valve 5, in a deactivated position (left), in a partially activated position (center), and in an activated position (right). In the deactivated position, the opening 8 in the first valve housing wall 11 of the slide valve 4 is not closed by the valve element 10, and in the activated position, the opening 8 in the first valve housing wall 11 of the slide valve 4 is closed by the valve element 10. In the partially activated position, the movement of the valve element 10 along the vertical direction is complete, and a displacement of the valve element 10 along the transverse direction has not yet occurred.

[0059] In the illustrated embodiment, a plurality of pneumatic actuators 3 are used to actuate the slide valve 5, specifically a first pneumatic actuator 3, which can also be referred to as valve actuator 14, and a second pneumatic actuator 3, which can also be referred to as second valve actuator 28. The first displacement of the valve member 10 along the vertical direction, i.e., from the deactivated position to the partially activated position, is effected by the movement of the actuator 15 of the valve actuator 14, whose first piston rod 17 is coupled to the valve member 10. The second displacement of the valve member 10 along the transverse direction, i.e., from the partially activated position to the activated position, is effected by the second valve actuator 28.The second valve actuator 28 is coupled to the first valve actuator 14 via its actuator element 15, which has a second working piston 29 and a second piston rod 30, such that a movement along the transverse direction of the actuator element 15 of the second valve actuator 28 results in a force being applied to the first valve actuator 14. The second pneumatic actuator 3 also has position measuring units 26 in the region of the first end position and the second end position. The first valve actuator 14 is rotatably mounted about a bearing 31 and is set into a tilting motion by the force applied.

[0060] By way of example, the second pneumatic actuator 3 is also designed as a double-acting pneumatic cylinder and has a further cylinder housing 32, which defines a further working chamber 33 in which the actuator element 15 is slidably mounted, with the second working piston 29 dividing the further working chamber 33 into a third pressure chamber 34 and a fourth pressure chamber 35. For the control of the movement of the actuator element 15 of the second pneumatic actuator 3, it is connected to the control device 2 via fluid lines (not shown). A mass flow measuring unit 23 and a pressure measuring unit 25 are each assigned to the third pressure chamber 34 and the fourth pressure chamber 35, and a position measuring unit 26 is located in the region of the first end position and in the region of the second end position.

[0061] To ensure the tightest possible closure of the opening 8, the valve element 10 has a circumferential, in particular rubber-elastic, sealing element 13 on its side facing the opening 8, wherein the pressure force required to close the opening 8 and acting on the sealing element 13 is provided by the second pneumatic actuator 3.

Claims

Claims 1. Method for operating a pneumatic system for industrial automation, comprising at least one pneumatic actuator (3) and a control device (2) for controlling a movement of an actuator element (15) of the at least one pneumatic actuator (3) from a first position to a second position and / or from the second position to the first position, comprising the steps: - Measuring the actual mass flow rate of pressurized fluid supplied to and / or discharged from the pneumatic actuator (3). - Providing a mass flow signal to the control device (2) - Measuring the actual pressure in a pressure chamber (20, 21, 34, 35) of the pneumatic actuator (3) - Providing the actual pressure as an actual pressure signal to the control device (2) - Determination of a pressure estimate in a pressure chamber (20,21,34,35) of the pneumatic actuator (3) - Comparing the actual pressure signal with the estimated pressure value - Providing a deviation parameter based on the comparison between the actual pressure signal and the estimated pressure value - Determination of position information of an actuator element (15) of the pneumatic actuator (3) based on the mass flow signal and the actual pressure signal and / or the pressure estimate value .

2. The method of claim 1, further comprising the step of: - Varying the actual mass flow supplied and / or discharged to the pneumatic actuator (3) to minimize the deviation parameter .

3. The method of claim 1 or 2, further comprising the step of: - Varying the actual mass flow supplied and / or discharged to the pneumatic actuator (3) to adjust the acceleration of the actuator element (15) based on an estimated position and / or an estimated velocity and / or the actual pressure and / or the estimated pressure value.

4. A method according to any of the preceding claims, further comprising the steps of: - continuous measurement of the position of the actuator element (15) of the pneumatic actuator (3) when moving into the first end position and / or into the second end position - Providing the measured position as an actual position signal to the control device (2) - Varying the mass flow supplied and / or discharged to the pneumatic actuator (3) to adjust the acceleration of the actuator element (15) based on the measured position and / or the velocity and / or the actual pressure and / or the estimated pressure value.

5. Method according to one of the preceding claims, wherein the pneumatic system (1) has a slide valve (4), wherein the slide valve (4) has a valve element (10) which is connected to the actuator element (15) of the pneumatic actuator and is moved along with the actuator element (15), and wherein the slide valve (4) has an opening (8) for the passage of a wafer which can be opened or closed by the valve element (10).

6. Method according to one of the preceding claims, characterized in that the pneumatic actuator (3) is a single- or double-acting pneumatic cylinder and the actuator element (15) comprises a drive piston (16, 29) and a piston rod (17, 30).

7. Method according to one of the preceding claims, characterized in that the pneumatic system (1) has a plurality of pneumatic actuators (3) in each of which the movement of an actuator element (15) from a first end position to a second end position and / or a movement from the second end position to the first end position is controlled by the control device (2).

8. Pneumatic system for industrial automation (1) , comprising: at least one pneumatic actuator (3) with an actuator element (15) , a control device (2) for controlling a movement of the actuator element (15) from a first end position to a second end position and / or from the second end position to the first end position and a mass flow measuring unit (23) for measuring an actual mass flow of pressurized fluid supplied to and / or discharged from the pneumatic actuator (3) and for transmitting the measured actual mass flow as a mass flow signal to the control device (2) .

9. Pneumatic system according to claim 8, further comprising at least one pressure measuring unit (25) for measuring an actual pressure in at least one pressure chamber (20, 21, 34, 35) of the pneumatic actuator (3) and transmitting the actual pressure to the control device (2) .

10. Pneumatic system according to claim 8 or 9, further comprising at least one position measuring unit (26) for continuously measuring an actual position of the actuator element (15) of the pneumatic actuator (3) when moving into the first end position and / or into the second end position and to transmit the actual position to the control device (2) .

11. Pneumatic system according to one of claims 8 to 10, further comprising a slide valve (4) , wherein the slide valve (4) has a valve element (10) which has an actuator element (15) and an opening (8) which can be closed by the valve element (10) for the passage of a wafer, and wherein the pneumatic actuator (3) serves to actuate the slide valve (10).

12. Pneumatic system according to one of claims 8 to 11, further comprising a plurality of pneumatic actuators (3) .

13. Pneumatic system according to claim 11 in combination with claim 12, wherein a first pneumatic actuator (3) of the plurality of pneumatic actuators (3) and a second pneumatic actuator (3) of the plurality of pneumatic actuators (3) serve to actuate the slide valve (4), wherein the first pneumatic actuator (3) is rotatably mounted and is configured to displace the valve member (10) along a direction of movement, and the second pneumatic actuator (3) is coupled to the first pneumatic actuator (3) for moving the first pneumatic actuator (3) into a tilting movement.

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