Vacuum valve

Abstract

The invention relates to a vacuum valve for use in medium, high or ultra-high vacuum systems. The vacuum valve comprises a valve housing defining a passage connecting a first opening and a second opening of the valve housing; a valve body and a complementary valve seat arranged in the passage, the valve body and / or the valve seat comprising a sealing member, and the valve body being movable along a linear axial direction between an open position and a closed position, wherein the valve body cooperates with the valve seat in the closed position to hermetically close the first opening; and an electromechanical actuation unit for actuating the valve body, comprising an electric motor and a mechanical conversion unit having an input portion in driving connection with the electric motor and an output portion in driving connection with the valve body, wherein the mechanical conversion unit converts a rotational output of the electric motor into a linear motion of the output portion to move the valve body in the axial direction. The invention also relates to a method of operating such a vacuum valve and to a vacuum valve comprising a weak force sealing member. One advantage of the vacuum valves according to the invention is that these vacuum valves have a relatively low energy consumption.

Description

Technical Field

[0001] This invention relates to a vacuum valve for use in medium, high, or ultra-high vacuum systems. Another aspect of the invention relates to a method for operating the vacuum valve. Background Technology

[0002] Medium, high, and ultra-high vacuum systems are used in many technical, industrial, and scientific applications. These types of vacuum (especially in the 100 to 10 ... -9 Vacuum conditions in the Pa range place very high demands on the design of components used in these systems. In particular, the valves in these systems must meet high standards because they must be able to reliably prevent gas leakage when closed.

[0003] Traditional vacuum valves are based on pneumatic or solenoid actuators. While these valves are generally reliable, they require considerable energy to operate and / or hold in the open or closed position. However, energy efficiency is an increasingly important issue due to considerations such as environmental and cost.

[0004] Therefore, one object of the present invention is to provide a vacuum valve with higher energy efficiency that can operate reliably. Summary of the Invention

[0005] According to a first aspect of the present invention, a vacuum valve is provided for medium, high, or ultra-high vacuum systems, the vacuum valve comprising:

[0006] A valve housing that defines a passage connecting a first opening and a second opening of the valve housing;

[0007] A valve body and a complementary valve seat are disposed in a channel, the valve body and / or the valve seat including a sealing member, and the valve body is movable in a linear axial direction between an open position and a closed position, wherein the valve body in the closed position mates with the valve seat to hermetically close the first opening; and

[0008] An electromechanical actuation unit for actuating a valve body includes a motor and a mechanical conversion unit. The mechanical conversion unit has an input section driven by the motor and an output section driven by the valve body. The mechanical conversion unit converts the rotational output of the motor into linear motion of the output section to move the valve body in an axial direction.

[0009] This electromechanical actuation unit can be very compact and allows for the efficient conversion of electrical input into actuating motion of the valve body. Because the vacuum valve according to the invention has relatively low energy consumption, it may not necessarily require a power grid to power its operation. The vacuum valve can be powered by a battery or capacitor, or it may be equipped with a solar panel.

[0010] The motor can be, for example, a brushed motor or a brushless motor (e.g., a stepper motor), or an internal rotor type or an external rotor type. The availability of alternative motor options provides flexibility in determining a solution with optimal overall characteristics.

[0011] Furthermore, the electromechanical actuation unit allows the valve body to be not only in the open or closed position, but also in any intermediate position. For example, appropriate motor control provided by an internal or external control unit can also influence the dynamic characteristics of the valve body's motion during valve opening and / or closing.

[0012] The valve body and / or valve seat may include more than one sealing member.

[0013] According to one embodiment of the invention, the mechanical conversion unit includes a lead screw that mates with a nut element. This conversion unit is inexpensive and can be easily resized to meet specific requirements.

[0014] For example, the output section may include a nut element. In this case, the nut element moves axially by the rotation of a lead screw, which is directly or indirectly achieved by a motor. However, it is also conceivable to provide an axially movable screw to hold the nut element in a fixed axial position.

[0015] According to one embodiment, at least one first elastic element (e.g., a spring) is provided, which is supported by the valve housing and acts on the valve body such that a force is applied to the valve body, thereby causing it to move into a closed position in the axial direction. This force is a biasing force supporting the closing movement of the valve body. This, in turn, means that in order to generate the required closing force during the closing movement of the valve body, the motor must provide less torque. Therefore, the size of the motor can be smaller and / or the energy required to drive the vacuum valve can be reduced.

[0016] According to one embodiment, the valve body is axially movable relative to the output portion. In other words, the valve body is not fixedly attached to the output portion to allow compensation for thermal effects and / or minor errors in the electromechanical actuation unit (especially minor errors in motor operation).

[0017] The electromechanical actuation mechanism may include at least one second elastic element (e.g., a spring) supported by the output portion and acting on the valve body, such that a force is applied to the valve body, thereby causing it to move axially away from the output portion. This biasing force helps to achieve the aforementioned compensation.

[0018] The output section and the valve body can be connected by a coupling unit that restricts their relative axial movement. The coupling unit can be configured to ensure that the valve body and the output section move together when the maximum permissible space between these components is reached (especially when the vacuum valve is open).

[0019] In embodiments that include a first elastic element and a second elastic element, the first elastic element may have higher elasticity than the second elastic element in order to obtain the desired valve characteristics.

[0020] According to one embodiment, the output portion is held rotatably fixed by a guide device. The guide device may include a protrusion that mates with a guide slot or groove extending in the axial direction. Alternative guide concepts may also be employed, such as guide rails and / or guide channels based on the external (non-rotationally symmetric) geometry of the output portion.

[0021] According to one embodiment, the motor and the input section are driven together via at least one speed reduction drive. This speed reduction drive allows for optimization of thrust and actuator linear velocity. The speed reduction drive may include, for example, gears, belts, and / or pulleys. However, a direct drive may also be used, where the motor's output component is directly coupled to the input section of the mechanical conversion unit.

[0022] According to one embodiment, the electromechanical actuation unit includes at least one locking device and / or locking feature to lock the output portion or valve body in a desired axial position. The locking function can be provided by a mechanical conversion device or a reduction drive (if present). For example, the mechanical conversion unit and / or reduction drive may have self-locking properties due to the specific design of their mechanical components. However, it is also conceivable to provide more than one locking device or feature to obtain alternative designs for improving packaging, cycle life, and energy efficiency. Locking methods include mechanical, electrical, and electromechanical concepts. An electric motor can also be used as a locking device, thus serving as an electrically operated locking device. An electrically operated clamping interruptor is an example of an electromechanical locking device.

[0023] The self-locking concept is associated with many unique advantages, such as lower average power consumption over time and less wear on the motor, valve switching unit, and related control units (electronics). In particular, when the electromechanical actuation unit is in a self-locking state, the motor can enter standby mode or even be completely shut off. In this case, specific motor holding interruption or active control is also obsolete. Another benefit is that the vacuum valve remains in its current state during power interruptions (e.g., when the valve body is open, closed, or in an intermediate position).

[0024] In one embodiment, a position sensor is provided to detect the position of the output section and / or the valve body. This sensor allows for closed-loop control because the data provided by the sensor can be used to control the motor. The sensor can be an encoder, an optical sensor, a Hall effect-based sensor, or any other suitable sensor.

[0025] Information regarding the position of the output section and / or valve body allows the dynamic characteristics of the electromechanical actuator to be determined and adjusted (if necessary) by controlling the motor accordingly. The valve body can also be easily positioned in the desired intermediate location to control the dynamic characteristics of airflow in the vacuum system, such as influencing, suppressing, or enhancing pressure-time curves, pressure peaks, gas velocity, flow-induced debris generation and movement, and pump inlet pressure.

[0026] Open-loop control of the motor can also be configured. For example, the actuation unit includes a stepper motor, which in turn includes a step counter. The data provided by the counter indicates the actual position or state of the output section.

[0027] According to a second aspect of the present invention, a vacuum valve is provided for medium, high, or ultra-high vacuum systems, the vacuum valve comprising:

[0028] A valve housing that defines a passage connecting a first opening and a second opening of the valve housing;

[0029] A valve body and a complementary valve seat are disposed in a channel, the valve body and / or the valve seat including a sealing member, and the valve body is movable in a linear axial direction between an open position and a closed position, wherein the valve body in the closed position engages with the valve seat to close the channel of the vacuum valve housing; and

[0030] Actuation unit for actuating valve body;

[0031] The sealing member has a non-circular geometry in a cross-section perpendicular to the first opening and / or is hollow and / or has a PTFE (polytetrafluoroethylene) material or coating and / or includes a fluoroelastomer material or coating. The hollow, coated and / or fluoroelastomer material comprising the sealing member may have a circular geometry.

[0032] Employing a sealing member that can be compressed with relatively weak forces and / or provides sufficient sealing performance when relatively weak forces are applied (“weak-force seal”) helps reduce the energy required to drive the vacuum valve. The concept of the second aspect of the invention can be combined with a vacuum valve according to the first aspect of the invention, and vice versa.

[0033] According to one embodiment, a first sealing member and a second sealing member are provided, wherein the first sealing member is fixed to the valve body, and the second sealing member is fixed to the valve housing. The first and second sealing members are arranged such that they contact each other during the closure of the vacuum valve. In this embodiment, when the valve body moves to the closed position, the two sealing members compress against each other. In most cases, compression between seals provides a more reliable seal at a given compressive force than compression between a seal and metal. Or in other words, a weaker force is required to achieve a sufficient seal in the vacuum valve.

[0034] The first and second sealing components can be fixed to the corresponding parts by vulcanization. The sealing components can be coated with PTFE and / or fluoroelastomer materials and are on the valve body and / or valve seat.

[0035] A vacuum valve according to the first and / or second aspect of the invention may include an actuation unit comprising an energy storage unit for supplying electrical energy to a motor. Since the concept according to the invention achieves a valve with lower energy consumption, a suitable energy storage unit (e.g., a battery pack) allows the motor to run for extended periods without being connected to the power grid. If the control unit for controlling the motor and / or monitoring the state of the vacuum valve does not have a wired connection (e.g., a wireless data connection is conceivable), the operation of the vacuum valve can be entirely wireless.

[0036] According to a third aspect of the present invention, a method is provided for operating a vacuum valve, particularly according to the above embodiments, the vacuum valve comprising:

[0037] A valve housing that defines a passage connecting a first opening and a second opening of the valve housing;

[0038] A valve body and a complementary valve seat are disposed in a channel, the valve body and / or the valve seat including a sealing member, and the valve body is movable in a linear axial direction between an open position and a closed position, wherein the valve body in the closed position mates with the valve seat to hermetically close the first opening; and

[0039] An electromechanical actuation unit for actuating a valve body includes a motor and a mechanical conversion unit. The mechanical conversion unit has an input section driven by the motor and an output section driven by the valve body. The mechanical conversion unit converts the rotational output of the motor into linear motion of the output section to move the valve body in an axial direction.

[0040] The motor is operated during the movement of the valve body to the closed position to reduce the speed of the valve body before and / or during the contact between the valve body and the valve seat.

[0041] In particular, if the sealing member is located on the valve body, the speed is reduced before the sealing member contacts the valve seat. When the sealing member is located on the valve seat, the speed can be reduced before the valve body contacts the sealing member. When the sealing member is located on both the valve seat and the valve body, the speed of the valve body can be reduced before the sealing members contact each other.

[0042] To illustrate, the reduction in valve body speed achieves a "soft landing" of the valve body within the complementary valve seat. This deceleration reduces the stress applied to the sealing components, and thus also reduces wear. Furthermore, by selecting an appropriate speed distribution, vibrations during the vacuum valve's closing process can be minimized. This, in turn, reduces the generation and / or transfer of fine debris particles within the vacuum valve, which can cause serious problems when introduced into the vacuum system.

[0043] According to one embodiment of the method, the motor is operated so that the movement of the valve body from the open position to the closed position takes a longer time compared to the movement of the valve body from the closed position to the open position. In particular, the motor is operated so that the compression of the sealing member during the movement of the valve body into the closed position takes a longer time compared to the decompression of the sealing member during the movement of the valve body out of the closed position.

[0044] When the vacuum valve is opened, the problems of vibration and / or stress in the sealing components and / or valve seat and / or valve body are significantly reduced. Therefore, the vacuum valve can be opened faster than it can be closed, thus improving its dynamic characteristics. This is particularly beneficial for decompression of the sealing components.

[0045] According to one embodiment of the method, in the closed position of the valve body, the operating motor is activated such that the force acting on the sealing member is not less than a predetermined threshold. This measure ensures that the vacuum valve can be reliably closed. The force acting on the sealing member can be determined based on data provided by at least one of a force sensor, a strain sensor, or a temperature sensor. In particular, data provided by a suitably positioned force sensor or strain sensor can be used to directly determine the force acting on the sealing member. The force can also be determined indirectly, for example, by estimating the force based on the temperature of the valve housing, valve seat, actuation unit, and / or valve body. According to one embodiment, the force acting on the sealing member is determined based on the operating parameters of the motor. This indirect determination of the force can be based on measured motor current or voltage data. For example, the current required for the motor to rotate a certain angle (e.g., less than 5°) can be used to estimate the force acting on the sealing member, since the current is substantially proportional to the force acting on the sealing member.

[0046] Optional additional sensors may be configured to monitor the state of the vacuum valve, which can be data sources for determining or estimating the aforementioned forces. The threshold may be a fixed value or may be determined based on the operating parameters of the vacuum valve and / or the vacuum system. Attached Figure Description

[0047] Figure 1 A cross-section of a first embodiment of the vacuum valve is shown.

[0048] Figure 2A perspective view of a cross section of the first embodiment is shown.

[0049] Figure 3 A perspective view of the first embodiment is shown.

[0050] Figure 4 A second embodiment of the vacuum valve is schematically shown.

[0051] Figure 5 A schematic top view of the second embodiment is shown.

[0052] Figure 6 A third embodiment of the vacuum valve is schematically shown.

[0053] Figure 7 A schematic top view of the third embodiment is shown.

[0054] Figure 8 A flowchart illustrating a visual approach to optimizing vacuum valve design is provided.

[0055] Figure 9 A first embodiment of a method for operating a vacuum valve is shown.

[0056] Figure 10 A second embodiment of the method for operating the vacuum valve is shown.

[0057] Figure 11 A first embodiment of a weak-force sealing member is shown.

[0058] Figure 12 A second embodiment of a weak-force sealing member in both uncompressed and compressed states is shown.

[0059] Figure 13 One embodiment of the connection unit is shown.

[0060] Figure 14 A third embodiment of a weak-force sealing device in an uncompressed state is shown.

[0061] Figure 15 A perspective view of a fourth embodiment of the vacuum valve is shown.

[0062] Figure 16 It shows Figure 15 A magnified view of a portion of it.

[0063] Figure 17 A cross section of the fourth embodiment is shown.

[0064] Figure 18 It shows Figure 17 A magnified view of a portion of it.

[0065] Figure label:

[0066] 10. Vacuum valve; 12. Valve housing; 14. Bottom component; 16. First chamber; 18. First opening; 20. Second opening; 22a, 22b. Flange portion; 24. Wall element; 26. Wall; 28. Guide device; 30. Valve cover element; 32. Second chamber; 34. Motor; 36. Gear drive; 38, 38a. Lead screw; 40, 40a. Nut; 42, 42a. Protrusion; 44, 44a. Axial slot or groove; 46. Sleeve; 47. First spring element; 48. End element; 50. Lift valve core; 52, 52a, 52b. Seal; 54. Second spring element Components; 56, Axial protrusion; 58, Bellows; 60, Valve seat; 62, Belt; 64, 66, Pulley; 68, Rod; 70, Guide element; 72, Guide opening; 74, Bearing bracket; 76, Bearing; 78, Output gear; 80, Input gear; 82, Groove; 84, Clearance; 86, Finger; 88, Groove; 90a, 90b, Axial wall; AM, Axial movement; S, Stroke; RA1, RA2 Rotation axis; D, Diagonal; P, Position; t, Time; SC, Seal contact; SR, SR1, Extrusion range; MMC, Metal-to-metal contact; StR, Stress relaxation; F, Force. Detailed Implementation

[0067] Figure 1 , Figure 2 and Figure 3 A vacuum valve 10 with a valve housing 12 is shown. The valve housing 12 includes a bottom member 14 that defines a first chamber 16 having a first opening 18 and a second opening 20. Both openings 18 and 20 are connected to flange portions 22a and 22b, which allow the vacuum valve 10 to be integrated into medium, high, or ultra-high vacuum systems. The upper side of the chamber 16 is covered by a wall element 24, which in turn abuts a wall portion 26 of a guide device 28. The wall portion 26, together with a valve cover element 30, forms a second chamber 32. In other words, the multi-part valve housing 12 defines two chambers 16 and 32, which respectively house the valve body (lift valve core 50) for sealing the opening 18 and the key components required for its actuation, as described below. The chamber 16 essentially serves as a passage between the openings 18 and 20.

[0068] The second chamber 32 houses the motor 34, which is driven by the lead screw 38 via a reduction drive 36. The reduction drive 36 may include, for example, a spur gear, a worm gear, and / or a planetary gear. The lead screw 38 engages with the nut 40 such that when the motor 34 is running and the lead screw 38 is rotated, the nut 40 moves axially (axial movement AM) as the protrusion 42 engages in the axial slot 44 of the guide device 28, thereby preventing the nut 40 from rotating.

[0069] Nut 40 is fixedly connected to sleeve 46. Sleeve 46 is provided with a first spring element 47, which is supported by the inner shoulder of sleeve 46 and acts on end element 48, which in turn contacts lift valve core 50 provided with seal 52. Seal 52 may be, for example, a conventional O-ring or a weak-force seal, as described above and further below.

[0070] The second spring element 54 is supported by an axial protrusion 56 of the guide device 28, which protrudes through an opening in the wall element 24 into the first chamber 16. The second spring element 54 acts on the lift valve core 50, thereby pushing it downward toward the opening 18. The second spring element 54 radially surrounds the lower part of the sleeve 46 and is further surrounded by a bellows 58 that separates the second spring element 54 from the interior of the first chamber 16.

[0071] To close the vacuum valve 10, the motor 34 is activated to drive the lead screw 38. The rotation of the lead screw 38 causes the nut 40 to move axially downwards, thereby also pushing the sleeve 46 downwards. This movement is transmitted via a first spring element 47 and an end element 48 on the lifting valve core 50, which is not fixedly connected to the sleeve 46. This movement is supported by a pre-compressed second spring element 54. Thus, the force provided by the spring element 54 acts parallel to the thrust applied to the lifting valve core 50 by the lead screw mechanisms 38, 40, which convert the rotation of the lead screw 38 into axial translation of components 40, 46, 47, 48, and 50. In this way, the second spring element 54 reduces the torque required to produce the axial translation and reduces the energy consumption of the motor 34. Another advantage is that the motor 34 can be relatively small, especially with the appropriate selection of the reduction drive 36.

[0072] When seal 52 contacts valve seat 60 surrounding opening 18, seal 52 begins to compress, and the process of sealing opening 18 begins. Compression of seal 52 stops at a given point, and lift valve spool 50 stops moving axially. At this point, lift valve spool 50 is in its closed position. Since there is a gap between lift valve spool 50 and sleeve 46, this is not a problem if motor 34 continues to operate for a short time. This only results in a reduction of the gap and further compression of the first spring element 47.

[0073] If open-loop control of motor 34 (e.g., a stepper motor) is configured, small errors in motor control can be compensated for by this gap. Alternatively, a position sensor can be provided to monitor the position of any one of components 40, 46, 47, and 50 to enable closed-loop control of motor 34.

[0074] With the lead screw mechanisms 38, 40 and / or the reduction drive 36 having a self-locking design, the lifting valve core 50 can be held in the closed position without energy. Spring elements 47, 54 press the lifting valve core 50 against the valve seat 60. In this case, the aforementioned clearance also compensates for different thermal expansions and / or stress relaxations of the components of the vacuum valve 10.

[0075] To open the vacuum valve 10, the lead screw 38 is rotated in the opposite direction under the appropriate control of the motor 34, thereby causing the sleeve 46, fixed to the nut 40, to move upward. Initially, the lift valve core 50 is still pressed downward by the spring elements 47, 54. However, as the sleeve 46 retracts, the gap between the sleeve 46 and the lift valve core 50 increases, and the force exerted on the lift valve core 50 by the first spring element 47 decreases. When the maximum gap is reached, the coupling mechanism, described in more detail below, engages the lift valve core 50 with the sleeve 46. The lift valve core 50 then moves upward together with the sleeve 46 against the force exerted by the spring element 54. The lift valve core 50 can move until it reaches the limit position defining the "fully open" state. However, the lift valve core 50 can be in any desired intermediate position between the closed position and the fully open position.

[0076] Figure 4 A second embodiment of the vacuum valve 10 is schematically shown. A motor 34 is coaxially mounted with a reduction drive 36, which is connected to a lead screw 38 via a belt 62 and pulleys 64 and 66. The lead screw 38 engages with a nut 40, which is fixedly connected to a rod 68 that carries a lift valve core 50 with a seal 52. In this embodiment, axial guidance is provided by a guide element 70 extending through a guide opening 72 in the nut 40. The guide element 70 acts, for example, as a guide rail. Details regarding the chamber 16 are omitted for clarity.

[0077] In this configuration, during the operation of the vacuum valve 10, the stroke S of the lifting valve core is parallel to the axial movement AM of the nut 40. However, both the stroke S and the axial movement AM are axial movements.

[0078] Figure 5 The top view shows the rotation axis RA1 of pulley 64 (and motor 34), the rotation axis RA2 of pulley 66 and lead screw 38, and the axial projection of rod 68, which are basically set on the diagonal D of valve cover 30. This arrangement is both simple and compact.

[0079] Figure 6 and Figure 7An alternative, compact arrangement is shown. The lead screw 38 is supported by a bearing bracket 74 including a bearing 76. The lead screw 38 is driven by a motor 34 connected to a reduction drive 36, which in turn drives an output gear 78 that meshes with an input gear 80 fixed to the lead screw 38. The lead screw 38 engages with a nut 40, which is axially movable but rotationally fixed. The nut 40 is connected to the lift valve core 50 via a rod 68. In this embodiment, the stroke S, axial movement AM, and rotation axis RA2 of the input gear 80 and the lead screw 38 are coaxially arranged.

[0080] Figure 8 A flowchart illustrating a visual exemplary method for optimizing the design of a vacuum valve according to the present invention and adapting it to market requirements is provided. In addition to energy efficiency, important objectives include, for example, optimized flow conductance, optimized actuation motion and dynamic characteristics, compact size, low impact velocity during the vacuum valve's closing process, temperature stability, reliable self-locking performance, and reproducible duty cycle. Non-performance-related issues (such as packaging, cost, and manufacturability) can also be considered during the optimization process of the vacuum valve.

[0081] The leftmost flow path requires the desired flow rate through the vacuum valve as input A1. Select appropriate parameters (A2) to generate the actual flow rate (A3), such as the valve core or seal diameter and valve core stroke. These parameters can be edited to change A3.

[0082] The next step on the right requires the desired sealing material as input (B1). Then, in step B2, parameters regarding further performance of the seal (e.g., its diameter, cross-section, and elasticity) and parameters describing how the seal is held (e.g., the geometry of the groove in which the seal is disposed, and its effect on the response due to relative thermal expansion) are selected. This information provides further insight into the expected and / or actual compressive force to be applied to the seal (B3). The aforementioned parameters can be edited in response to this information. This allows for optimization of the performance of the first spring element 47 (B4).

[0083] The next step on the right requires, for example, the desired actuation curve, required torque and speed, and required self-locking force for the linear motion and thrust of the lifting valve core 50 as input (C1). Relevant parameters include, for example, the lead screw diameter and / or the characteristic friction between the lead screw and the nut (C2). This specifically produces the actual linear motion and the thrust response to the drive torque and speed of the relevant components. This allows for a further understanding of the actual compressive force and the actual self-locking force (C3). This allows for optimization of the performance of the second spring element 54 (C4).

[0084] The rightmost step in the process uses the required motor type (D1) (e.g., brushed motor (D2), stepper motor (D3), internal rotor motor (D4), or external rotor motor (D5)) as constraints. Relevant parameters include, for example, motor torque, the provided speed, and parameters regarding and / or defining the duty cycle (D6). This yields the actual required or expected "power input" value (D7). The selection of a suitable motor can be optimized based on these parameters.

[0085] In D8, it must be determined whether a reduction drive or equivalent device is needed or desired. One relevant parameter here is the reduction ratio (D9), which yields the expected actual torque and speed for driving the vacuum valve, as well as the actual self-locking force (D10).

[0086] It should be emphasized that the optimization process described above is merely exemplary. Additional and / or modified optimization methods may be employed. The execution order of the optimization process is entirely up to the individual.

[0087] Figure 9 An exemplary duty cycle of the vacuum valve according to the invention is shown in the position (P)-time (t) graph. At t = 0, the lift valve core 50 of the vacuum valve is in the fully open position (position P1). When the motor 34 is started, the lift valve core 50 accelerates and moves relatively quickly toward the valve seat 60. The speed of the lift valve core 50 is actively reduced before the seal 52 begins to be compressed. This is reflected in the reduced slope of the dashed motion curve before the seal 52 contacts the valve seat 60 (seal contact SC, position P2). During the compression of the seal 52, the speed of the lift valve core 50 is further reduced until it reaches 0 in the closed position (position P3, time t1). The seal 52 has been compressed to the extent shown by SR (compression range). The vacuum valve is appropriately controlled to avoid metal-to-metal contact (MMC) between the lift valve core 50 and the valve seat 60. The above method achieves a "soft landing" of the lift valve core 50 during the closure of the vacuum valve.

[0088] If one or more components of the electromechanical actuation unit (e.g., lead screw mechanisms 38, 40 and / or reduction drive 36) have self-locking capabilities, the lifting valve core 50 can be held in the closed position without supplying electrical power to the motor 34.

[0089] At t2(P4), the vacuum valve begins to open. As already noted, when the vacuum valve is opened, the problems of vibration and / or stress in the sealing member 52 and / or valve seat 60 and / or valve body 50 are significantly less pronounced than during closure. Therefore, the lifting of the valve core 50 can be accelerated rapidly. Consequently, the decompression of the seal 52 is much faster than its compression.

[0090] In the illustrated embodiment, the valve core 50 reaches its maximum speed when the seal 52 disengages from the valve seat 60 (position P5). The valve core 50 moves further away from the valve seat 60 until it reaches the fully open position again (P6 at t3).

[0091] As can be seen from the above description, the duty cycle of the vacuum valve according to the invention can be asymmetrical in terms of opening and closing. In the above example, the time taken to close the vacuum valve (t0 to t1) is longer than the time taken to open the vacuum valve (t2 to t3). This concept can be easily implemented by the electromechanical actuation unit of the vacuum valve according to the invention, because such an actuation unit allows for very precise control of the position and dynamic characteristics of the valve body / lifting valve core. Suitable position-time curves and / or thrust curves can also be designed for each application.

[0092] Figure 10 The effect during the closed state of the vacuum valve is shown in the force (F)-time (t) graph. The horizontal dashed line indicates the minimum thrust (F) that should be applied to seal 52 to ensure a proper seal. min This value is lower than the compressive force F1 obtained after the vacuum valve is properly or properly closed. Different thermal expansion of the components of the vacuum valve may cause a reduction in thrust or compressive force (see ΔT). If this effect is detected (e.g., by using a suitable sensor to monitor the position of the lifting valve core 50 or other components of the actuation unit), the motor 34 is activated to compensate for the effect with an appropriate response (see Actuator Response AR) to keep the force within the desired seal compressive range SR1. Stress relaxation of the mechanical components involved can also be another reason for a reduction in the force applied to the seal 52 (see StR).

[0093] The energy consumption of the vacuum valve can also be reduced by using so-called “weak force seals” (i.e., seals that can be properly compressed by applying relatively small forces and / or seals that have sealing performance under weak forces) (regardless of the nature of the actuation unit).

[0094] Seals comprising PTFE material or coating and / or comprising fluoroelastomer material or coating are examples of such weak-force seals. The desired performance can also be achieved by deviating from the circular cross-section of the seal and selecting a non-circular geometry. For example, as... Figure 12 The diamond-shaped seal 52 shown on the left (set in the groove 82, uncompressed) when a given force is applied ( Figure 12 The deformation of the right-hand side is greater than that of a conventional O-ring of the same size. If the seal 52 is at least partially hollow (see...), Figure 11 This effect will be enhanced. Suitable hollow seals or seals with a softer core can also have the same effect. Figure 11 The rhombus geometry shown has different geometric shapes.

[0095] Figure 13 An exemplary embodiment of the mechanism connecting the lift valve core 50 and the sleeve 46 is shown. In the open state of the vacuum valve, the spring-biased end element 48 presses the lift valve core 50 away from the sleeve 46, thereby creating a gap 84 between the components. In this state, the protrusions of the fingers 86 of the sleeve 46 engage with the upper end of the groove 88 of the lift valve core 50, thereby holding it in that position. In the closed state of the vacuum valve, the lift valve core 50 has moved toward the sleeve 46 to compensate for, for example, minor errors in motor control and / or effects caused by gradual compression of the seal and / or thermal effects. Figure 13 (as shown in the example).

[0096] During the opening of the vacuum valve, the sleeve 46 moves upward, while the lifting valve core 50 remains pressed against the valve seat 60 by the spring elements 47 and 54. The lifting valve core 50 is only actively lifted from the valve seat 60 when the protrusion of the finger 86 engages with the upper end of the groove 86.

[0097] It should be easy to imagine that there are many alternative institutions that can provide equivalent or similar types of connections.

[0098] Figure 14 Another embodiment of the weak-force seal is shown. This weak-force seal includes seals 52a and 52b respectively disposed on the lift valve core 50 and valve seat 60 in their uncompressed state. During the closing process of the vacuum valve, seals 52a and 52b come into contact with each other and are gradually compressed. As described above, compared to conventional arrangements, achieving a sufficient seal in this vacuum valve requires a weaker force.

[0099] Figures 15 to 18 A compact vacuum valve 10 is shown, which has an axially movable lead screw 38a that engages with a nut 40a that remains axially fixed. The nut 40a is driven to rotate by a motor 34a disposed between axial walls 90a and 90b.

[0100] The starting of motor 34a causes nut 40a to rotate. This, in turn, causes axial movement of lead screw 38a. Protrusion 42a, fixed to the axial wall 90a and engaging with the axial groove 44a of lead screw 38a, prevents lead screw 38a from rotating. A functionally equivalent mechanism can be conceived.

[0101] Vacuum valve 10 can operate as described in the vacuum valve embodiment above. It should also be noted that, if desired, the various features described in conjunction with one embodiment can be implemented in other embodiments. This is particularly applicable when combined with… Figure 1 and Figure 2The functions provided by the spring elements 47 and 54 in the illustrated embodiments.

Claims

1. A method for operating a vacuum valve, the vacuum valve comprising: A valve housing that defines a passage connecting a first opening and a second opening of the valve housing; A valve body and a complementary valve seat are disposed in the channel, the valve body and / or the valve seat including a sealing member, and the valve body is movable in a linear axial direction between an open position and a closed position, wherein the valve body engages with the valve seat in the closed position to hermetically close the first opening; as well as An electromechanical actuation unit for actuating the valve body includes a motor and a mechanical conversion unit. The mechanical conversion unit has an input portion driven and connected to the motor and an output portion driven and connected to the valve body. The mechanical conversion unit converts the rotational output of the motor into linear motion of the output portion to move the valve body in the axial direction. The motor is operated during the process of the valve body moving to the closed position, such that the speed of the valve body is reduced before and / or during the contact between the valve body and the valve seat. In the closed position of the valve body, the motor is operated such that the force acting on the sealing member is not less than a predetermined threshold. The force acting on the sealing member is determined based on the operating parameters of the motor.

2. The method of claim 1, wherein operating the motor causes the valve body to move from the open position to the closed position in a longer time than the valve body to move from the closed position to the open position.

3. The method according to claim 1 or 2, wherein operating the motor causes the compression of the sealing member during the movement of the valve body into the closed position to take a longer time than the decompression of the sealing member during the movement of the valve body out of the closed position.

4. The method of claim 1, wherein the force acting on the sealing member is determined based on data provided by at least one of a force sensor, a strain sensor, or a temperature sensor.

5. The method according to claim 1, wherein the mechanical conversion unit includes a lead screw that cooperates with the nut element.

6. The method of claim 5, wherein the output portion includes the nut element.

7. The method of claim 1, wherein at least one first elastic element is provided, the at least one first elastic element being supported by the valve housing and acting on the valve body such that a force is applied to the valve body, causing it to enter the closed position in the axial direction.

8. The method of claim 7, wherein the valve body is movable relative to the output portion along the linear axial direction.

9. The method of claim 8, wherein the electromechanical actuation unit includes at least one second elastic element supported by the output portion and acting on the valve body such that a force is applied to the valve body, causing it to move away from the output portion in the axial direction.

10. The method of claim 8, wherein the output portion and the valve body are connected by a coupling unit that restricts the relative movement of the output portion and the valve body along the axial direction.

11. The method of claim 9, wherein the first elastic element has a higher elasticity than the second elastic element.

12. The method according to claim 1, wherein the output portion is held in a rotating and fixed position by a guide device.

13. The method of claim 12, wherein the guiding device includes a protrusion that engages with a guide slot or groove extending along the axial direction.

14. The method according to claim 1, wherein the motor and the input portion are driven together by at least one speed reduction drive device.

15. The method of claim 1, wherein the electromechanical actuation unit includes at least one locking device and / or locking feature to lock the output portion or the valve body in a desired axial position.

16. The method of claim 15, wherein the mechanical conversion unit has a self-locking function.

17. The method of claim 1, wherein a position sensor is provided to detect the position of the output portion and / or the valve body.

18. The method of claim 1, wherein the sealing member has a non-circular geometry in a cross section perpendicular to the first opening and / or is hollow and / or has PTFE material or coating and / or includes fluoroelastomer material or coating.

19. The method according to any one of claims 1, 2, 4 to 18, wherein the electromechanical actuation unit includes an energy storage unit for supplying electrical energy to the motor.

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