Compensation element, method and system for actively attenuating a medium - Patents.com

Abstract

The present invention relates to a compensation element (1, 10-16) for actively damping oscillations of a medium (24), in particular a fluid. The compensation element comprises a hollow body (20) having an internal volume (23), in which a compensation volume (41) is formed, the hollow body (20) further having at least two openings (21, 22) connecting the compensation volume (41) to fluid lines (51, 52) used for the supply and discharge of the medium (24), the compensation element (1, 10-16) being non-destructively removable from the fluid lines (51, 52), and at least one actuator (30) capable of enlarging or reducing the compensation volume (41) during operation.

Description

[Technical field]

[0001] The present invention generally relates to a compensation element and a method and system for actively damping the oscillations of a medium, in particular a fluid, by means of which pressure fluctuations in, for example, a pipeline system can be compensated. [Background technology]

[0002] The transmission of vibrations through media, especially fluids, has long been a problem. If the liquid is incompressible, the vibrations are only slightly damped during propagation, and therefore can propagate over long distances. This also applies, for example, to liquid-filled pipelines in which sensitive machines and equipment are connected, placing correspondingly high demands on a constant pressure in the pipeline. In order to reduce possible pressure fluctuations, various solutions have been developed.

[0003] Thus, for example, expansion vessels are known, which are essentially flexible compensators, making it possible in a closed pipeline system to expand the pipeline volume when the pressure increases and, conversely, to reduce the pipeline volume when the pressure decreases, but this leads to a lower pressure downstream of the compensator or vessel.

[0004] For certain applications, for example in precision equipment that places very high demands on constant pressure conditions, a relatively large volume may be required for the expansion vessel in order to effectively compensate for pressure changes. Pressure changes, especially in the case of incompressible fluids such as water, can lead to oscillations that can be reflected multiple times in the pipeline and thus transmitted over long distances. In this case, for example sensitive equipment, such as electron beam equipment or sensors, can be disturbed or even damaged. Volume changes also occur, which can have a detrimental effect on connected equipment or installations.

[0005] Furthermore, pressure changes can lead to deformations that can result in further or even worse damage.

[0006] Against this background, such solutions are used rather for applications with relatively low demands. Thus, such expansion vessels are used, for example, to keep the pressure constant in heating circuits or to prevent water hammer in domestic water circuits. Usually, such expansion vessels are adjusted to a specific frequency range.

[0007] Another solution provides for compensating or at least reducing the pressure fluctuations at various frequencies by a combination of Helmholtz-like resonators in the flow, which are correspondingly selected depending on the volume and pipe length to be damped in order to adapt the frequency characteristics.

[0008] Such a damping element for damping oscillations in a pressure line is described in DE 10 2013217119 A1 on the example of a clutch for an automobile. In this case, a hollow cylindrical damper is proposed which operates on the basis of a Helmholtz resonator and which has a double-walled housing for forming a damper volume. Such a resonator is typically adapted precisely to a specific frequency field and can then effectively filter this frequency field. In the case of a larger frequency spectrum, the damper volume must be enlarged.

[0009] A hydraulic damping element is described in DE 10 2011 081 538 A1, also by way of example of a hydraulic release system for a clutch in the powertrain of a motor vehicle, which comprises a rotatably mounted damping mass, which is rotated by the volume flow through a fluid line.

[0010] Although such damping elements may be reliable, they are quite complex in construction and, moreover, are generally relatively large, for example compared to the pipe diameter, and furthermore, they need to be individually adapted to the volume and pipe system.

[0011] Other damping systems work with electro-rheological or magnetorheological fluids, as is known for example from the applicant's EP 2759735. In this case, the damping can be adjusted individually and continuously via a regulating circuit. This is relatively time-consuming and, moreover, is subject to strict time constraints due to delayed response characteristics.

[0012] Therefore, a compensation or damping element that does not have these drawbacks is desirable.

[0013] It is desirable for the compensation or damping element to have a structural size that is as small as possible.

[0014] Furthermore, it is advantageous that the compensation or damping elements can be at least partially flexibly adapted to the specific characteristics of the volumes and pipelines, i.e. there is no need to provide special compensation or damping elements for each volume or each pipeline.

[0015] Furthermore, it is advantageous for it to be easily integrated into an existing pipeline system.

[0016] It is further desirable for the compensation or damping element to be usable with a variety of media, in particular a variety of fluids, including, for example, media containing highly corrosive ultrapure water (UPW), such as may be used in the semiconductor industry, other aggressive and / or corrosive media, or liquids, such as dielectric liquids, for example liquids containing large amounts of fluorine.

[0017] The inventors have worked hard to achieve this goal. Summary of the Invention [Means for solving the problem]

[0018] The above-mentioned object is achieved in an unexpectedly simple manner by a compensation element for active damping of the oscillations of a medium, in particular a fluid, as well as a method and a system for active damping of the oscillations of a medium, in particular a fluid, according to one of the independent claims. Preferred embodiments or refinements of the invention emerge from the respective dependent claims.

[0019] The subject of the invention is therefore a compensation element for active damping of medium oscillations, which comprises: a hollow body having an internal volume, a hollow body, in whose internal volume a compensation volume is formed, the hollow body further having at least two openings by which the compensation volume can be connected to the surroundings; at least one actuator capable of enlarging or reducing the compensation volume during operation; It is a compensation element that has

[0020] The actuator may be located within the interior volume according to a preferred embodiment of the present invention, but may also be located outside the interior volume.

[0021] The medium may in particular comprise a fluid which may be in gaseous or liquid form. The compensation element may be particularly advantageously used with a low compressible or incompressible fluid, in particular a liquid. Such a fluid has a viscosity of at least 1.0·10 at a standard pressure of 0.1 MPa and a temperature of 10° C. 9 Pa, preferably at least 1.5·10 9 Pa, particularly preferably at least 2.0·10 9 It is understood to be a fluid having a bulk modulus (compressibility) of 1 Pa. Fluids particularly suitable for the present invention therefore include oil, water or oil-water mixtures.

[0022] In one embodiment of the present invention, it is also provided for using demineralized water as a medium, i.e. for the compensation element to be operated with purified and / or demineralized liquid. Based on the electrical conductivity, demineralized water can be classified into purified, low-salt water having a conductivity of 1-50 μS / cm (purified water), pure water having a conductivity of 0.1-1 μS / cm (pure water) and highly pure water having a conductivity of 0.055-0.1 μS / cm (ultrapure water).

[0023] The invention is particularly suitable for operation with purified, pure or high purity water or "ultrapure water" (UPM) such as that required and used in the semiconductor industry. In these liquids further parameters and quantities such as total oxidizable carbon (TOC), particles or dissolved gases may be checked and reduced. Thus, the invention also relates in one aspect to a compensation element configured for use with low salt water, pure water and high purity water.

[0024] Another embodiment of the invention provides for the use of industrial or dielectric fluids, particularly liquids, such as fluorine-containing fluids, such as fluorine-containing liquids. In general, the medium may comprise an erosive or corrosive liquid or gas.

[0025] The medium may, for example, be contained in a pipeline, a fluid line, a hydraulic section, a pressure line, or generally be contained or guided within any other suitable container or vessel.

[0026] In the following, for brevity, reference will be made only to the fluid line, but this is also intended to include a hydraulic section, a pressure line, a line system or generally any other vessel or container suitable for containing a medium, in particular a fluid, which, within the meaning of the invention, is at least partially filled with the medium, in particular a fluid, to be damped during operation.

[0027] In certain embodiments, the hollow body may be provided by the fluid line itself, in other words the internal volume of a given section of the fluid line may act as the compensation volume.

[0028] The opening of the compensation element may be connected to the fluid line in a force-locking and / or form-locking manner. For this purpose, suitable connection means or joints may be provided for forming a force-locking and / or form-locking connection between the fluid line and the opening. Advantageously, these connection means or joints are selected in such a way that they allow for simple assembly and preferably destructive removal. In this way, the compensation element can be easily attached and, for example, welded seams can be dispensed with, which may also be advantageous with regard to possible deformations or crack formations. In the event of a possible malfunction, the compensation element can be easily exchanged and replaced.

[0029] According to another embodiment of the invention, it is also possible and conceivable to connect the compensation element directly to the piece of equipment or to the device to be cooled and / or damped, for example by water. Of course, several compensation elements may also be provided in one equipment or one device, for example to cool a larger surface or area.

[0030] The compensation elements mounted in this way can be connected to a fluid line, which can be not only in a linear configuration but also in a mesh configuration, so that, for example, larger areas can also be cooled in a particularly advantageous manner.

[0031] The connection with the fluid line can also be formed after the assembly of the compensation element. The invention therefore also relates in one aspect to a compensation element which is directly connectable or connected to an installation piece or device. It is self-evident that the compensation element can be provided with suitable attachment means for this purpose. The attachment can take place, for example, by gluing. However, in another embodiment it can also be advantageous if the connection is designed to be releasable without destruction.

[0032] For active damping of oscillations, the compensation element can be connected to the fluid line in a fixed and fluid-tight manner, whereby fluid-tightness is understood to mean that no medium or fluid can escape at the connection between the compensation element and the fluid line during normal operation, i.e. in predefined pressure or temperature conditions.

[0033] The section of the fluid line that is exposed to potential pressure fluctuations can be connected to the first opening of the hollow body, and the second opening is preferably also connected to the fluid line.

[0034] The first opening is also referred to below as the inlet or inlet opening, and the second opening as the outlet or outlet opening, where the distinction between the first and second openings is with regard to the functionality of the openings or of the fluid lines connected to them, and not with regard to their technical configuration.

[0035] The second opening of the hollow body thus provides an outlet for the medium which can reach via the inlet into the internal volume of the hollow body, in particular into the compensation volume. Pressure fluctuations on the inlet side in the fluid line can be at least reduced or preferably compensated for by the compensation element. In other words, pressure fluctuations on the inlet side are merely reduced and transmitted on the outlet side or ideally are no longer transmitted.

[0036] Pressure fluctuations are to be understood as pressure surges or pressure differences that may occur due to dynamic pressure changes of a viscous medium in a fluid line. This may be, for example, a pressure increase in a line, which may occur when a shutoff valve is quickly opened or closed, or the start and stop of a pump in a fluid line. In certain cases, dynamic pressure changes are also referred to as pressure shocks or water hammers.

[0037] The magnitude of the pressure surge varies and may depend on various factors, such as the volume of the fluid line or the compressibility of the medium. In general, the magnitude of the pressure surge in a less compressible liquid fluid is higher than in a gaseous medium, where the mass inertia of the fluid is also important.

[0038] Pressure changes are transmitted by pressure waves, also called pressure fluctuations in the context of the present invention. Pressure waves are longitudinal waves. The braking or acceleration of a fluid in a fluid line requires some force that can be determined using Newton's second law. Pressure changes or pressure fluctuations can cause oscillations about the fluid line, especially in incompressible fluids such as water.

[0039] The oscillations may be transmitted by the fluid lines and may be transmitted over larger sections by the fluid lines, so damping may also be required here.

[0040] To decouple or damp vibrations in fluid lines or installations or individual joints, it is also possible to use, as long as the boundary conditions permit, structural elements such as, for example, rubber or rubber-like structural elements, grooved structural elements, U-shaped lines or bellows.

[0041] These oscillations of the fluid lines can have several undesirable effects: for example, deformations and volume changes can cause changes in the spacing relative to the plant or equipment to be cooled, which can lead to stresses in the plant or equipment to be cooled, which can lead to deformations of the area to be cooled.

[0042] Additionally, pressure surges can cause damage in or within the relevant systems, for example sensitive equipment such as electron beam equipment or sensors can be disrupted or even damaged.

[0043] Therefore, the pipeline may burst in the worst case, or the pipeline holder may be damaged. The fittings, pumps, or foundations connected to the fluid pipeline may also be damaged by the pressure surge. The problem is that these damages, which are relatively small, are usually not immediately visible, and subsequent damage may occur.

[0044] In particular, pressure surges or pressure fluctuations can be particularly critical in highly sensitive devices, machines or installations, such as devices or equipment in the field of nanotechnology, or for example electron beam devices with highly sensitive optical devices.

[0045] This concerns, for example, water-cooled circuits to which machines, installations or devices of the semiconductor industry or installations are connected, which have parts that are highly sensitive or sensitive to pressure fluctuations in the water-cooled circuit, where pressure fluctuations significantly below 1 Pa, for example below 0.1 Pa or even below 0.01 Pa, can already lead to deviations that can disturb or impair the process, or whereby the required precision can no longer be maintained and / or damage can occur.

[0046] Water has a compressibility that is significantly higher than that of, for example, oil, and is therefore nearly incompressible, which allows pressure changes to propagate quickly and with great force within a fluid line.

[0047] The compensating element according to the invention serves to reduce or compensate for pressure surges in the fluid line, thereby damping, reducing or ideally completely compensating for pressure fluctuations or oscillations in the fluid system. The compensating element according to the invention thus allows the pressure in the fluid line to be maintained at a predetermined level while at the same time allowing very small deviations from that value.

[0048] In this context, damping can be considered as the removal of pressure-related energy from a closed liquid circuit. Damping in this sense is the reduction of pressure fluctuations in a medium, rather than damping in the sense of damping of mechanical oscillations. To remove this energy, work is required that is not 100% efficient and leads to heat generation. It is desirable for the construction of the compensation element to ensure that no significant heat is supplied to the medium in which the pressure fluctuations are eliminated.

[0049] Ideally, this means that the inlet amplitude of the oscillations, measured on the outlet side, is attenuated to zero, so that a perfect compensation of the oscillations that occur is obtained. However, in the sense of the present invention, attenuation can also be understood as meaning that the inlet amplitude of the oscillations to be attenuated is reduced by at least 50%, preferably at least 60%, particularly preferably at least 70%, or even by 90%, 99% or more, for example by 99.5% or more. The outlet amplitude at the outlet side of the compensation element is therefore preferably less than 50%, less than 40%, less than 30%, less than 10%, or even less than 1%, for example less than 0.5%, with respect to the inlet amplitude. Furthermore, in the sense of the present invention, it is specified that this attenuation takes place in as short a time as possible.

[0050] This relates to a frequency range of about 0.01 Hz to about 20 kHz, preferably 0.1 Hz to 100 Hz.

[0051] Mass flow controllers ("MFCs") can certainly be used to regulate the mass flow rate to a target value, but these controllers usually do not have the dynamic range required to control and regulate very precise or very large mass flow rates, since the mass flow rates are rather inertial.

[0052] At switch-on, a time-delayed overshoot can occur, i.e. the target value can be exceeded or over-controlled, or the target value can be exceeded or under-controlled, which is detrimental to the invention, which deals with extremely sensitive processes.

[0053] The compensating element according to the invention can therefore also serve in another aspect of the invention to provide a very accurate constant mass flow rate of fluid from switch-on to switch-off, in which case the inertia during switch-on and switch-off is low.

[0054] In the sense of the present invention, for this purpose, part of the internal volume of the hollow body can be utilized, in particular a compensation volume, which can be actively expanded or contracted in order to compensate for or at least minimize the pressure fluctuations occurring in the fluid line.

[0055] This compensation volume provides a volume that can be purposefully and actively changed by the actuator during operation in order to compensate for pressure fluctuations in the fluid line. The compensation volume can be reduced or expanded within the meaning of the invention by an active movement, for example a stroke movement, of the actuator. In other words, the actuator is configured to vary the compensation volume during operation and thereby compensate for pressure fluctuations in the fluid line.

[0056] The actuators may include drives based on magnetic, piezoelectric or electrostatic principles. Such actuators are distinguished by their direct and rapid response behavior to a predefined or suitable area of ​​use and, moreover, their mechanical movements can be handled very precisely by corresponding electrical drive controls. In the developments of the invention, combinations are also envisaged, whereby drives based on different principles can be combined with one another in order to expand the range of use.

[0057] In general, by applying a voltage that can be adjusted by a controller, a deformation of the drive can be induced, which can result in a volume change of the drive within the hollow body. By enlarging the compensation volume remaining within the hollow body, positive pressure surges can be accommodated, so to speak. By decreasing the compensation volume, negative pressure changes can be accommodated.

[0058] In one embodiment of the present invention, it is provided for selecting a drive device for the actuator that comprises a piezoelectric material that can work in liquid fluids or is resistant to liquid fluids.

[0059] According to an embodiment of the present invention, the actuator may be protected so that it can be operated together with or in contact with aggressive or corrosive fluids, in particular "ultrapure water" and / or fluorine-containing fluids. Thus, for example, a coating or protective layer resistant to the fluid may be provided. In the case of aggressive or corrosive fluids, such as low-salinity or highly pure water, for example, suitable anti-corrosion coatings are conceivable, such as those based on or containing tantalum, inconel, molybdenum or combinations thereof. PVD coatings, for example, are also conceivable. It is self-evident that the remaining joints and / or parts of the installation should also be correspondingly protected.

[0060] In this way, it is possible to arrange the actuator directly in the internal volume. The advantage of this embodiment of the invention is that the piezoelectrically active material or the piezoelectric drive can be arranged directly in the cavity, and no additional built-in parts are required to protect the drive, since the piezoelectric drive can be in direct contact with the fluid from the fluid line. In this way, the compensation element can be maintained very simply and compactly.

[0061] By suitable selection of the geometry of the piezoelectric material and its arrangement in the internal volume of the hollow body, it can be ensured that the volume change or stroke movement of the piezoelectric material leads to the desired change of the compensation volume, which according to one embodiment of the invention relates to the volume that would arise if the actuator were arranged in the internal volume of the hollow body in a rest position, i.e. with its normal size without any electrical influence.

[0062] In a refinement of the invention, it is provided that the movement of the actuator on the inlet side of the hollow body is greater than the movement on the outlet side. This improves the damping or absorption of the oscillations and, overall, improves the power output. This can be achieved, for example, if the opening is arranged on one side of the hollow body and the piezoelectric material is arranged on the opposite side in the hollow body. In this case, the distance of the piezoelectric material to the inlet opening is shorter than the distance of the piezoelectric material to the outlet opening. If the hollow body has a rectangular cross-sectional shape, this can be achieved, for example, very simply, by a surface of the body of the piezoelectric material that is correspondingly inclined towards the opening. The inclination can result in an angle α, which can advantageously be at least 1°, preferably at least 5°, particularly preferably at least 10°.

[0063] In a likewise preferred embodiment of the invention, the internal volume is divided by a flexible diaphragm into two partial volumes, so that in addition to the compensation volume, a second volume, also called balancing volumes in the following, is formed. The compensation volume is arranged in correspondence with the space adjacent to the opening, so that it can receive the medium from the fluid line. The compensation volume in the hollow body is thus surrounded by the flexible diaphragm, so that the medium cannot flow out. For this purpose, the actuator can likewise be arranged advantageously outside the compensation volume.

[0064] The flexible diaphragm can, for example, contain or be formed as a bellows. Materials that come into consideration are, for example, elastomers which have sufficient elasticity for the required deformations.

[0065] However, when used under vacuum or low vacuum, certain materials may be problematic and therefore cannot be used with particularly aggressive or corrosive media. Therefore, for the present invention, particularly other materials or hard, less elastic materials of suitable construction form are also used, especially metallic materials such as stainless steel or special steel. During operation, the compensation volume can accommodate a medium, for example a fluid from the fluid line.

[0066] The advantage of such an arrangement is that the actuator is protected from the medium by a flexible diaphragm, which allows the use of other materials or actuators that are not resistant or can be made resistant to the medium of the fluid line. Furthermore, the compensation volume can be changed as described above by a corresponding movement of the actuator.

[0067] In a refinement of the invention, a pressure body is provided which can be moved by the actuator and act on the flexible diaphragm, thereby improving or facilitating the introduction of forces from the actuator to the flexible diaphragm.

[0068] The movement of the actuator, and thus the size of the compensation volume, can be monitored by an electronic calculation unit and controlled by an adjustable controller, with which set values ​​for the actuator can be determined and transmitted to the actuator for controlling the compensation, thereby controlling the voltage applied to the actuator to change the size of the compensation volume.

[0069] According to an embodiment of the present invention, the adjustment of the actuator, and therefore the adjustment of the compensation volume size by the calculation unit, is performed on the basis of the deviation of the current pressure at the inlet opening from a predefined pressure. Thus, at the inlet opening, there is a predefined pressure P and a pressure difference ΔP Ε The total pressure composed of the above can be adjusted.

[0070] Therefore, the total pressure on the inlet side is PE=P+ΔΡ Ε Alternatively or additionally, the total pressure at one or more points in the fluid line can also be measured on the side exposed to potential pressure fluctuations.

[0071] For this purpose, corresponding sensors or pressure measuring devices may be provided in the inlet openings of the hollow body and / or in the fluid lines, which are explained in more detail below.

[0072] The calculation unit can thus utilize data on the pressure situation prevailing in the fluid line, and it can then calculate a set value for the voltage of the actuator. The set value thus corresponds to the voltage that must be applied to the actuator in order to produce a volume change in the compensation volume that is able to compensate for the pressure difference. In this way, the actuator is able to detect the pressure deviation ΔΡ Ε A movement adapted to the pressure difference P can be carried out, which can reduce or ideally completely compensate the pressure difference by changing the compensation volume in the hollow body. Thus, the pressure fluctuations occurring in the fluid line can be minimized or ideally completely compensated, so that the total pressure P at the outlet opening A Regarding P A ≒P or ideally P A =P holds true.

[0073] In other words, in this embodiment of the invention, it is provided that the compensation volume is changed by a corresponding movement of the actuator based on the pressure fluctuations in the fluid line so that a predefined value for the pressure results at the outlet of the hollow body, whereby the pressure fluctuations are zero or nearly zero.

[0074] The regulation of the compensation element may be configured according to the "feedback control" method or as a fed-back regulation (closed-loop control) in order to reduce pressure fluctuations. The required movement of the actuator is determined by a suitable filter in the control device. When designing the regulation, it is advantageous to take into account the nonlinear and / or hysteresis effects of the actuator, e.g. the piezoelectric material, in order to eliminate overshoots, i.e. excessively strong damping.

[0075] A refinement of the invention provides that the flow velocity of the medium, in particular the fluid, is also taken into account when adjusting the compensation element, for which purpose corresponding measuring devices or sensors, for example pitot tubes, can be provided at suitable points in the fluid line.

[0076] Alternatively or additionally to this fed-back regulation, in another embodiment of the invention, a "feed-forward" method or disturbance value input can also be incorporated into the regulation in order to further increase efficiency. For this purpose, pressure fluctuations are measured downstream, i.e. in a fluid line connected to the outlet opening of the hollow body, correspondingly filtered and fed to the regulation circuit.

[0077] Another embodiment of the present invention provides that the compression force acting on the actuator is taken into account as a pre-control parameter as a regulation parameter. The purpose of this regulation strategy is to control the actuator so that changes in the compression force are minimized or compensated for. Thus, the force acting on the actuator is kept as constant as possible. Additionally, the actuator may be provided with a force sensor or force transducer, which may be arranged between the actuator and the compensation volume, and which detects changes in the compression force due to changes in the compensation volume.

[0078] In this embodiment of the invention, an actuator, for example a piezoelectric drive, may be combined with a piezoelectric based force sensor.

[0079] The advantage of piezoelectric-based force sensors is that they cannot measure constant DC pressure, but only recognize force changes. In such piezoelectric ceramic elements, the action of force generates a charge distribution, which is proportional to the force and can be measured. Piezoelectric-based force sensors can also be used to measure pressure or shear forces. The advantage when using piezoelectric-based force transducers is that these force transducers can measure with high dynamics.

[0080] The advantage of this regulation strategy is that no pressure sensors are required in or on the fluid lines, which can be very sensitive and thus require extensive monitoring of their functionality during operation.

[0081] To measure the total pressure, in one embodiment of the present invention, a special pressure sensor is provided, which makes it possible to measure the fluctuations or differences in the total pressure with an accuracy of 0.1 Pa or better, preferably 0.05 Pa or 0.01 Pa, even in the case of high pressures, for example pressures of 50 kPa or more, preferably 100 kPa or more.

[0082] The pressure sensor according to the invention is configured to detect relative pressure. In such a pressure sensor, the pressure difference on the two sides of the sensor element is evaluated. If the mean pressure is the same on both sides, fluctuations in the mPa range can be measured. The inlet of the pressure sensor can be directly connected to the fluid line. This makes it possible to ensure that all pressure fluctuations are detected on this side. However, a high total pressure also prevails on this side. A pressure feedback can be given to another inlet of the pressure sensor from a precisely selected distance downstream of the fluid line. The use of a capillary with an appropriate length and an appropriate diameter and the utilization of the volume in the pressure sensor ensures that pressure fluctuations above a certain frequency cannot reach this side of the pressure sensor. In this way, a low-pass filter can be configured with a cut-off frequency determined by the geometry of the capillary passage and the volume of the pressure sensor. This configuration ensures that the pressure sensor does not measure a constant pressure, but only detects fluctuations above the cut-off frequency of the low-pass filter. This principle can be used for feed-forward sensors by connecting the capillary downstream of a pressure actuator. For feedback sensors, both the main connection and the capillary are connected downstream of the pressure actuator.

[0083] In addition to the above-mentioned embodiments for the compensation element for actively damping the vibrations of the medium, various other embodiments are possible and conceivable, in particular with regard to the actuators and sensors, some examples of which are given below. Of course, it is also possible and conceivable to combine these embodiments with one another. Moreover, it is self-evident that such a list should not be considered as limiting.

[0084] In an advantageous embodiment of the invention, The compensation elements are divided into three active elements, namely: an optional pressure sensor provided on the inlet side of the compensation element, which measures, on the upstream side, disturbances penetrating into the compensation element; an actuator configured to vary the size of the compensation volume so as to be able to influence pressure variations in the medium; an optional pressure sensor provided downstream at the outlet side of the compensation element, which can be used as a feedback sensor; The device may include:

[0085] For most embodiments, at least one pressure sensor is provided, or two pressure sensors as described above are used, which can serve to improve performance. These three elements can be combined to form one unit, or can be used as three separate elements, which can be connected to (short) lines, hoses or pipe elements as required.

[0086] The change in the compensation volume is an important aspect of the invention. This change can be achieved by a piston-like element that moves up and down, but also by deformation of a closed compensation volume containing a liquid. The compensation volume can be a flexible hose or tube that can be deformed in a deliberate and controllable manner, or a type of bellows element that is compressed or expanded to produce the desired volume change.

[0087] In a refinement of the invention, therefore, a compensation element is provided which actively damps the oscillations of a medium, in particular a fluid, in which a hollow body with an internal volume is already provided by a fluid line.

[0088] The internal volume of the fluid line thus provides a compensation volume that can be expanded or contracted by the actuator during operation. The actuator can be arranged outside the internal volume. The fluid line can be at least partially curved and formed with a bend. The actuator can be arranged between two curved sections of the fluid line located on opposite sides of each other and can be fixedly connected to the exterior of these sections. During operation, the actuator can apply a pulling or pushing movement to both sections of the fluid line, which can cause them to contract or push them away from each other.

[0089] In this way, the size of the internal volume provided by the fluid line can be varied, and it is self-evident that the fluid line can be correspondingly elastically configured in order to support the movements by the actuator.

[0090] The fluid lines can for this purpose be manufactured, for example, from elastic plastic.

[0091] However, in applications under vacuum or low vacuum, in the lithography field or in electron beam equipment, and / or when used in aggressive or corrosive media, plastics may be problematic and therefore may not be usable. Metallic materials, such as stainless steel or special steel, are therefore also prescribed or, alternatively or additionally, are provided with a coating, such as a PVD coating.

[0092] The bend may be formed as a full circle or a complete winding of the fluid line. The effect can be further increased if more than one turn is provided, for example two, three or four turns.

[0093] In yet another refinement of this embodiment of the invention, a compensation element is provided for actively damping the oscillations of a medium, in particular a fluid, in which a hollow body having an internal volume is likewise provided by a fluid line, the internal volume of the fluid line thus providing a compensation volume which can be enlarged or reduced during operation by an actuator, which may be arranged outside the internal volume.

[0094] According to this embodiment, the fluid line may be formed straight. The fluid line may be fixed in position via at least two bearing points arranged at a distance from one another, and the actuator may be arranged preferably in the middle between the two bearing points. The actuator is connected to the outside of the fluid line, preferably approximately in the middle between the bearing points, on the opposite side of the bearing points.

[0095] If the actuator applies a tensile or compressive force to the fluid line during operation, this can cause a radial movement of the fluid line between the two support points, and therefore a displacement of the fluid line in this section, which can also change the compensation volume and be adapted to compensate for pressure fluctuations.

[0096] In yet another refinement, it is provided that the side of the fluid line facing away from the action side of the actuator is fixed in position. The pressing force of the actuator can move the wall of the fluid line on the side facing the actuator in the direction of the opposite wall of the fluid line, so that the compensation volume can also be reduced. In this embodiment, a higher pressing force of the actuator is required compared to the above-mentioned embodiment with only two bearing points.

[0097] It will be appreciated that even in these embodiments, some degree of flexibility or elasticity of the fluid lines should be taken into consideration.

[0098] The invention therefore relates in another aspect to a compensation element for actively damping oscillations of a medium, in particular a fluid, in which the hollow body with an internal volume is already provided by the fluid line itself, and the volume change required for actively damping the oscillations can be brought about during operation by a substantially radial displacement of the fluid line as a whole or simply by a displacement of one wall of the fluid line by means of an actuator.

[0099] In a further refinement, it is provided that the fluid line is made flexible in its longitudinal direction. For this purpose, the fluid line can, for example, contain a type of bellows, which allows an axial length change of the fluid line instead of a radial displacement. For this purpose, the actuator can be arranged axially parallel, and by means of a corresponding tensile or compressive force, a longitudinal change of the fluid line in the region of the bellows can be caused, which can also result in a volume change.

[0100] The invention therefore relates in another aspect to a compensation element for actively damping oscillations of a medium, in particular a fluid, in which the hollow body with an internal volume is already provided by the fluid line itself, and the volume change required for actively damping the oscillations can be caused by a longitudinal change in the fluid line.

[0101] According to the invention, in another aspect, there is provided a method for active damping of vibrations in a medium, in particular a fluid, comprising the following steps: - providing a compensation element; - detecting the total pressure of the medium in the fluid line by means of a pressure sensor; - the inlet pressure difference ΔΡ with respect to a predefined pressure P Ε and - calculating setpoints for electrical parameters, in particular voltage, for the actuators and transmitting these setpoints to the actuators; - varying the compensation volume by means of an actuator based on a set value for reducing or increasing the compensation volume so that the change in volume allows the pressure difference to be compensated for; Includes.

[0102] In a preferred embodiment of the present invention, the method includes a compensation element as described above.

[0103] Another aspect of the invention includes a system for active damping of vibrations or agitation of a medium, particularly a fluid, configured to perform a method for active damping of vibrations or agitation of a medium, particularly a fluid, as described above, and which may include a compensation element as described above.

[0104] The system according to the invention may be used very advantageously for cooling machines, installations or other devices, which machines, installations or devices are protected from pressure fluctuations and thus from the fluctuations associated with pressure fluctuations.

[0105] In general, the compensation element according to the invention or the system according to the invention can also be used in various installations or processes in which it is desirable to adjust the mass flow rate to a target value as accurately and / or quickly as possible in order to actively damp vibrations or oscillations of a medium and / or to ensure a time-limited mass flow rate of a fluid, for example for mixing fluids.

[0106] These may be, for example, various processes or installations in the chemical industry, the semiconductor industry, in the field of lithography, or may be, for example, electron beam equipment, reactor chambers, etc.

[0107] The system may comprise a fluid line which is at least partially filled with a medium, in particular a fluid, for example water or oil, and during operation a defined total pressure of, for example, 1 Pa, 100 Pa, 1 kPa, 10 kPa or 100 kPa can be adjusted.

[0108] The compensation element according to the invention makes it possible to compensate for pressure fluctuations during operation in the system, which may be less than or equal to + / - 10 mPa, preferably less than or equal to + / - 5 mPa, particularly preferably less than or equal to + / - 5 mPa.

[0109] The invention can thus be used in fluid lines or in machines, installations or other devices connected to fluid lines that are highly sensitive to pressure and / or temperature fluctuations, for example in the semiconductor industry, thus preventing, for example, deformations in or at machines, installations or other devices, for example in the semiconductor industry.

[0110] Considered here, for example, are water-cooled circuits to which devices from the semiconductor industry or semiconductor installations are connected and which have parts which are sensitive or react to pressure and / or temperature fluctuations in the water-cooled circuit.

[0111] In one aspect, the present invention also relates to a system for controlling the mass flow rate of a medium, in particular a fluid, comprising a compensation element according to the invention as described above.

[0112] The system may be used for fluid metering or fluid mixing in another aspect of the invention.

[0113] This mass flow rate may for example refer to a fluid circulating in a circuit in a reactor chamber, whereby any kind of block flow or mass flow rate can be flexibly defined and better realized, since the inertia of the system is very small.

[0114] Further details of the invention emerge from the description of the illustrated embodiments and the accompanying claims. [Brief description of the drawings]

[0115] [Figure 1] 1 is a cross-sectional view showing the basic structure of a compensation element according to the invention for active damping of medium oscillations; [Diagram 2] 1 shows the basic structure of a compensation element according to the invention for active damping of medium oscillations in a cross-section based on an embodiment in which the internal volume is divided into a compensation volume and a balancing volume; FIG. [Diagram 3] 1 shows a cross-sectional view of the basic structure of a compensation element according to the invention for active damping of medium oscillations, based on an embodiment in which the internal volume is divided into a compensation volume and a balancing volume, in a further embodiment including a force sensor arranged on the actuator. [Figure 4] FIG. 1 shows an embodiment of a system for actively damping vibrations of a medium by means of a compensation element. [Diagram 5] FIG. 1 shows the basic structure of a pressure sensor that is particularly suitable for a compensation element. [Figure 6] 4 shows a side view of the basic structure of another compensation element according to the invention for active damping of medium oscillations, in which the hollow body is already provided with a fluid line, which is at least piecewise curved. [Figure 7] FIG. 1 shows a side view of the basic structure of yet another compensation element according to the present invention for actively damping medium oscillations, in which the hollow body is already provided with a fluid line, which includes at least one straight section. [Figure 8] 8 is a side view showing the basic structure of yet another compensation element according to the invention for active damping of medium oscillations, based on the embodiment shown in FIG. 7, with continuous support of the fluid line at least in the linear section. [Figure 9] 1 shows a side view of the basic structure of yet another compensation element according to the invention for active damping of medium oscillations, in which the hollow body is already provided by a fluid line and the volume change takes place in the longitudinal direction of the fluid line. [Figure 10] FIG. 13 shows in comparison the response behavior of the adjustment according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0116] In the following detailed description of the preferred embodiments, for the sake of clarity, substantially identical parts in these embodiments are designated by the same reference numerals. However, in order to more clearly illustrate the present invention, the preferred embodiments illustrated in the drawings are not necessarily drawn to scale.

[0117] FIG. 1 shows in a cross-sectional view the basic structure of a compensation element 1 according to the invention for actively damping oscillations of a medium (shown in the figure for the sake of clarity only by a refracting line 24), in particular a fluid, in one embodiment.

[0118] The compensation element 1 in the exemplary embodiment shown in FIG. 1 is configured as a compensation element 10 with an actuator 30 which is arranged in the inner volume 23 of the hollow body 20 .

[0119] In the following drawings further preferred configurations and embodiments of the compensation element 1 according to the invention, designated 11, 12, 13, 14, 15 and 16, are shown.

[0120] Compensation elements 1, 10, 11, 12, 13, 14, 15 and 16 are a hollow body 20 having an internal volume 23, a hollow body 20, in whose internal volume 23 a compensation volume 41 is formed, the hollow body 20 further having at least two openings 21, 22, which openings 21, 22 can connect the compensation volume 41 to the surroundings; at least one actuator 30 arranged in the internal volume 23 and capable of enlarging or reducing the compensation volume 41 during operation; It is equipped with:

[0121] When designing the compensating elements 1, 10, 11, 12, 13, 14, 15 and 16, care should be taken to avoid as far as possible turbulence, which may also be caused by the compensating elements themselves.

[0122] The medium 24 may be present in gaseous or liquid form, and in this embodiment includes a liquid fluid having low compressibility, such as oil or water. The medium 24 is contained within a pipeline system, fluid line, hydraulic section, pressure line, or generally within any other suitable container or vessel.

[0123] Fluid lines 51, 52, 53 are drawn in Fig. 4 purely as an example and for clarity, showing an embodiment of a system 100 for active damping of vibrations of a medium 24, in particular a fluid, in which a compensation element 11 is used. Fluid line 51 represents a fluid line through which medium 24 is supplied. To this end, fluid line 51 may be connected, for example, to a pump 54, drawn in Fig. 4 purely for clarity.

[0124] The arrangement is such that the pressure fluctuations to be compensated occur in the fluid line 51, which thus constitutes a supply line in the flow direction. In the embodiment shown in Figures 1, 2, 3 and 4, the fluid line which is arranged downstream of the compensation element 11 in the flow direction and which is guided away from the compensation element 11 is given the reference number 52. The system 100 shown in Figure 4 is explained in more detail below.

[0125] For the sake of clarity, the fluid lines have not been drawn in Fig. 1. During operation, the fluid lines and the compensation volume 41 are filled with the viscous medium 24, in this example a liquid fluid. In an embodiment, the fluid lines and the compensation volume 41 are completely filled with fluid.

[0126] The medium 24 may in particular comprise low-salt water, pure water as well as highly pure water or "ultrapure water" as required and specified in particular for the semiconductor industry. It is also possible to use the compensation element together with fluorine-containing media, in particular fluids, such as fluorine-containing liquids, in particular water.

[0127] In general, medium 24 may include erosive and / or corrosive fluids, ie, liquids and gases.

[0128] The openings 21, 22 of the compensation element 10 are, during operation, connected in a friction-locking and / or positive-locking manner to the fluid lines 51, 52. For this purpose, suitable connection means are provided for creating a friction-locking and / or positive-locking connection between the fluid lines 51, 52 and the openings 21, 22, such as sleeves, threaded fastenings or other suitable joints.

[0129] In the exemplary embodiment, these connections can be removed without destruction, thus allowing not only a simple installation but also a simple replacement of the compensation element. For active damping of the oscillations, the compensation element is mechanically fixed and fluid-tightly connected to the fluid lines 51, 52. Mechanically fixed is understood in this context to mean that the connections are sufficiently resistant to pulling out and vibrations during operation, which is ensured for the application by suitable structural dimensions and the selection of materials of the joining partners.

[0130] When the corresponding fluid lines 51, 52 are assembled, the first opening 21 is used during operation as an inlet or inlet opening for supplying the medium 24 and the other opening 22 is used as an outlet or outlet opening for discharging the medium 24.

[0131] The opening 22 of the hollow body 20 thus provides an outlet for the medium 24 which, during operation, can flow via the inlet 21 into the internal volume 23 of the hollow body 20. Pressure fluctuations in the fluid line 51 supplying the fluid can be at least reduced or ideally completely compensated for by the compensation element. In other words, the pressure fluctuations on the inlet side are only reduced and transmitted or ideally are no longer transmitted in or into the fluid line 52 connected to the outlet 22.

[0132] The oscillations occurring at the inlet 21 with the inlet amplitude are damped so that the outlet amplitude at the outlet 22 is smaller than the inlet amplitude. The outlet amplitude at the outlet 22 of the compensation element is therefore preferably less than 50%, less than 40%, less than 30%, less than 10% or even less than 1%, for example less than 0.5%, based on the inlet amplitude.

[0133] In FIG. 1, reference numeral 71 denotes a pressure P+ΔP applied to the inlet side. Ε is marked and, with reference number 72, the pressure P applied on the outlet side is visually marked.

[0134] Pressure fluctuations or pressure surges may occur based on dynamic pressure changes and may be transmitted by the medium 24 in the fluid lines 51. An excessively high pressure surge may cause damage to the system 100 or to machines 50, equipment, or other devices connected to the system 100, for example in the semiconductor industry. Fittings, pumps 54, or foundations directly connected to the fluid lines 51, 52 may also be damaged by the pressure surge.

[0135] At least a part of the internal volume 23 of the hollow body 20 is defined to be used as a compensation volume 41 which can be actively expanded or contracted in order to compensate or at least minimize pressure fluctuations occurring in the fluid lines 51, 52. Longitudinal waves in the viscous medium 24 which are caused by these pressure surges can be, so to speak, received by the compensation volume 41.

[0136] This compensation volume 41 provides a volume that can be purposefully and actively changed by the actuator 30 in order to compensate for this pressure variation in the fluid lines 51, 52 during operation. For this purpose, the actuator 30 can reduce or expand the compensation volume 41 by a movement, for example a stroke movement.

[0137] 1, the actuator 30 is arranged on the inner wall in the internal volume 23 of the hollow body 20. This allows for a particularly simple construction. In this case, the geometry of the actuator 30 and thus the selection of the volume occupied by the actuator 30 are selected such that when the actuator 30 is arranged in the rest position in the hollow body 20, a compensation volume 41 results on the basis of the residual volume.

[0138] In this embodiment of the invention, a drive with piezoelectric material is provided for the actuator 30, which can operate in a liquid medium or is resistant to the medium 24.

[0139] For this purpose, the drive has a corrosion-resistant coating based on materials including, for example, tantalum, Inconel, molybdenum or combinations thereof. PVD coatings are also possible. Also suitable materials may be certain high-purity plastics including, for example, PVDF-HP, ECTFE, or ceramic materials such as SiC.

[0140] This embodiment is particularly advantageous in that further built-in components, for example for protecting the actuator 30, can be omitted. In this way, the compensation element 10 can be maintained very simply and compactly. The geometry and the material of the actuator 30 are selected in such a way that the movement of the piezoelectric material during operation brings about the desired change of the compensation volume 41.

[0141] In general, the actuator 30 may have a different geometry, may be made of different materials and may be based on magnetic, piezoelectric or electrostatic principles. It is advantageous if the actuator 30 has a direct and fast response behavior.

[0142] Application of a voltage causes a deformation of the actuator 30, which leads to a volume change of the actuator 30 within the hollow body 20. By enlarging the compensation volume 41, positive pressure surges can be accommodated so to speak. A reduction in the compensation volume allows negative pressure changes or negative pressures to be accommodated.

[0143] In the embodiment of the invention shown in Fig. 1, the movement of and / or the spacing of the actuator 30 relative to the inlet side in the region of the inlet opening 21 is greater than the spacing on the outlet side in the region of the opening 22. This improves the damping characteristics.

[0144] In the present embodiment, this is achieved by an inclined surface 31 of the piezoelectric body. The inclination, indicated by the angle α in Fig. 1, results in different spacings for the two openings 21, 22. The angle α is at least 1°, preferably at least 5°, particularly preferably at least 10°. In the illustrated embodiment, the angle α is approximately 5°.

[0145] In another embodiment of the invention, it is provided for the division of the internal volume 23 into two partial volumes. Figures 2 and 3 show the basic structure of two compensation elements 11, 12 according to the invention for active damping of oscillations of a viscous medium 24 in a cross-sectional view based on two embodiments in which the internal volume 23 is divided into a compensation volume 41 and a balancing volume 42.

[0146] A flexible diaphragm 43 is provided which separates the compensation volume 41, resulting in a balancing volume 42 within the internal volume 23. The compensation volume 41 is likewise arranged in correspondence with the space adjacent to the opening, so that the compensation volume 41 can receive the medium 24 from the fluid lines 51, 52. The compensation volume 41 is therefore enclosed within the hollow body 20 by the flexible diaphragm 43, so that the medium 24 cannot flow out.

[0147] An advantage of this embodiment is that for example the actuator 30 is arranged protected outside the compensation volume 41 and is thus protected from direct action by the medium 24. This also allows the use of other materials or actuators which are not resistant to the viscous medium 24. The compensation volume 41 can furthermore be changed by a corresponding movement of the actuator 30.

[0148] The flexible diaphragm 43 may, for example, comprise a bellows or be formed as a bellows as suggested in figures 2 and 3. As materials, generally, elastomers, for example rubber, having sufficient elasticity for the required deformation, or metallic materials such as stainless steel or special steel in a corresponding construction type are considered. When selecting, it is to be borne in mind that the required pressure values ​​occurring during operation can be maintained.

[0149] During operation, the compensation volume 41 receives a medium 24, for example a fluid from a fluid line 51. In the embodiment of the inventive compensation element 11 shown in Fig. 2, a pressure body 44 is provided which can be moved by the actuator 30 and in so doing act on the flexible diaphragm 43. This allows for an improved or simplified introduction of forces from the actuator 30 to the flexible diaphragm 43.

[0150] The movement of the actuator 30 , and therefore the size of the compensation volume 41 , is controlled by a controller 94 which is monitored and regulated by an electronic computing unit 95 .

[0151] In this case, the calculation unit determines, based on a stored program or a value table, a setpoint value for the actuator 30, which is transmitted to the actuator 30 in order to control the compensation. For this purpose, a controller or another element suitable for control can also be used. The setpoint value relates to at least one electrical parameter, in this example the voltage applied to the actuator 30. The movement of the actuator 30 or its extension length is controlled by the applied voltage. This correspondingly influences and adjusts the size of the compensation volume 41.

[0152] In a preferred embodiment of the invention, the adjustment of the actuator 30 (closed-loop control) and thus the size of the compensation volume 41 is performed by a calculation unit on the basis of the deviation of the current pressure from a predefined pressure at the inlet opening 21. Thus, during operation, the inlet opening 21 is supplied with a predefined pressure P and a pressure difference ΔP. ΕA total pressure consisting of

[0153] Therefore, the total pressure on the inlet side is P Ε =P+ΔΡ Ε Alternatively or additionally, the total pressure at one or more points in the fluid line 51 can be measured on the side that is exposed to potential pressure fluctuations.

[0154] In FIG. 4 this is shown diagrammatically by two pressure sensors 61, 62, which are arranged on the one hand to the inlet 21 and on the other hand to the fluid line 51. If the pressure sensor 62 of the fluid line 51 is arranged with a sufficient distance from the opening 21, some lead time can be set, which is based on the detection of pressure changes occurring downstream during operation, first by the pressure sensor 62 and then, with a time lag, by the pressure sensor 61. This makes it possible to control the actuator 30 in advance, so that pressure differences can be compensated even better. The drive control of the actuator 30 takes place in real time. In this way, pressure differences can be compensated in real time.

[0155] For this purpose, the adjustment is advantageously configured with a wide bandwidth so that it can react both to very slow changes, for example in the range of less than 0.01 Hz, and also to high frequencies up to 10 kHz. This can be done both analogously and digitally. Essentially suitable adjustments can be found in the applicant's EP 1 840 681 A1, which is entirely the subject of the present invention and is therefore fully incorporated.

[0156] The calculation unit uses stored algorithms to determine a set point for the voltage to be applied to the actuator 30 based on the data from the pressure sensors 61,62.

[0157] Instead of fixedly programmed algorithms for controlling (open-loop control) or adjusting (closed-loop control) the compensation elements, in a refinement of the invention it is also conceivable to use "machine learning" methods or artificial neural networks as an auxiliary for adjustment.

[0158] This may be useful, for example, when multiple compensation elements are desired to be controlled and regulated by multiple actuators together and / or when multiple compensation elements are grouped together to form a larger, more complex fluid line complex or network. In yet another refinement of the invention, for the control or regulation strategy, other data or parameters of another installation, machine or system connected to the complex may be taken into account, for example room temperature or temperature at or within the installation or machine 50.

[0159] For the regulation, a PID controller can also be used.

[0160] In this way, the actuator regulation can be put into a self-learning mode, for example, to identify specific structures in the pressure changes, so that compensation can be performed more quickly and more accurately. For this purpose, pressure sensors may be arranged at several points in the fluid lines 51, 52, 53, for example upstream and downstream of pumps, valves or similar joints, so that information about pressure changes can be detected very early.

[0161] Therefore, in one embodiment of the present invention it is also provided that the flow velocity of the medium 41, in particular the fluid, is taken into account when adjusting the compensation element.

[0162] The actuator 30 is driven by a pressure ΔP Ε Since the movement is adapted to the deviation of the pressure difference P, the pressure difference in the hollow body 20 is reduced or ideally completely compensated by the adaptation of the compensation volume 41. Thus, the pressure fluctuations occurring in the fluid line 51 can be minimized or ideally completely compensated, so that for the total pressure P at the outlet opening 22, PA ≒P or ideally P A = P, and therefore ΔΡ Ε ≒0 Pa or ΔΡ Ε =0Pa holds true.

[0163] The regulation is performed according to an embodiment of the invention according to the "feedback control" method or as a fed back regulation. The required movement of the actuator 30 is determined by a suitable filter in the control device. When designing the regulation, non-linear and / or hysteretic effects of the actuator 30, e.g. the piezoelectric material, are already taken into account in order to eliminate overshoots, i.e. excessively strong damping.

[0164] Alternatively or additionally to this fed-back regulation, in another embodiment of the invention, a "feed-forward" method or disturbance value input can also be incorporated into the regulation in order to further increase efficiency. For this purpose, pressure fluctuations are also measured downstream, i.e. in the fluid line 52 connected to the outlet opening 22 of the hollow body 20 in this example. In FIG. 4, a further pressure sensor 63 is drawn in this respect purely by way of example.

[0165] While in these embodiments the pressure sensor is arranged in correspondence with the component guiding the medium 24, i.e. the inlets 21, 22 or the fluid lines 51, 52, FIG. 3 shows an embodiment of a compensation element 12 based on the embodiment shown in FIG. 2, but additionally comprising a force sensor or force transducer 32 provided in the actuator 30, which is therefore arranged between the actuator 30 and the compensation volume 41.

[0166] In this embodiment, the force sensor 32 is arranged between the actuator 30 and the pressure plate 44. In this embodiment of the invention, the compression force acting on the actuator 30 is used as a pre-control parameter as a regulation parameter. The force difference ΔF is then: ΔF=ΔP Ε*A, where A is the size of the acting surface. In this case, the aim of the adjustment is to minimize or ideally completely compensate the force difference acting on the actuator 30, so that ΔF≈0N or ΔF=0N.

[0167] The compensation volume 41 is varied during operation as a function of the compressive force acting on the actuator 30. The advantage of this method is that no pressure sensors in or at the fluid lines 51,52 are required.

[0168] To measure the total pressure, in one embodiment of the invention a special pressure sensor 70 is provided, which can be used particularly well together with a compensation element, which is shown diagrammatically in its basic configuration in FIG.

[0169] The pressure sensor 70 detects the relative pressure in the fluid line 51, in which case the pressure difference on the two sides of the sensor element is evaluated. If the mean pressure is the same on both sides, fluctuations in the mPa range can be measured.

[0170] The inlet of the pressure sensor 70 is connected directly to the fluid line 51 via the supply line 73. This ensures that all pressure fluctuations can be detected on this side. Pressure feedback is provided to the second inlet side of the pressure sensor 70 at a specific distance downstream of the fluid line 51. The use of a capillary 74 with an appropriate length and a volume in the pressure sensor 70 with an appropriate diameter ensures that pressure fluctuations above a certain frequency cannot reach this side of the pressure sensor. In this way, a low-pass filter is constructed with a cut-off frequency determined by the geometry of the capillary passage 74 and the volume of the pressure sensor 70. With such a structure, the pressure sensor 70 does not measure a constant pressure, but only detects fluctuations above the cut-off frequency of the low-pass filter. This principle can be used for feed-forward methods.

[0171] In this way it becomes possible to measure the fluctuations or differences in total pressure with an accuracy of 0.1 Pa or better, preferably 0.05 Pa or even 0.01 Pa, both in the case of high pressures, for example 50 kPa or more, preferably 100 kPa or more.

[0172] Other suitable pressure measurement methods may include laser interferometers or acceleration sensors to measure radial and / or axial pressure differences, also within the fluid lines.

[0173] Particularly suitable for the present invention are measurement methods or sensors which allow the measurement of a pressure difference.

[0174] 6 shows in a side view the basic structure of another compensation element 13 according to the invention for active damping of oscillations of a medium 24, in which the hollow body is already provided by a fluid line 51. This fluid line 51 is at least partially of curved design.

[0175] Thus, the internal volume 23 of the fluid lines 51, 52 provides a compensation volume 41 that can be expanded or contracted during operation by the actuator 30. The actuator 30 is, in this embodiment, arranged outside the internal volume 23. The fluid line 51 is at least partially curved or formed with a curved portion.

[0176] The actuator 30 is arranged between two curved sections 56 located on opposite sides of the fluid line 51 and is rigidly connected to these sections 56. During operation, the actuator 30 can exert a pulling or pushing movement on the two sections 56 of the fluid line 51, so that the sections 56 can be contracted or pushed apart from each other. For this purpose, a further force transmission element 34, for example a rod or tube, can be provided.

[0177] In this way, the size of the internal volume 23 provided by the fluid lines 51, 52 can be varied. It is self-evident that the fluid line 51 is correspondingly designed elastically and can be manufactured, for example, from an elastic plastic. In the present exemplary embodiment, a hose is provided.

[0178] The bend may be formed as a full circle, as shown in the example, or as a complete winding of the fluid line 51. The effect can be further increased if more than one turn is provided, for example two, three or four turns.

[0179] 7 shows in a side view the basic structure of yet another compensation element 14 according to the invention for active damping of oscillations of a medium 24, the hollow body being likewise already provided by a fluid line 51. Instead of a curved section, the fluid line 51 according to this embodiment comprises at least one straight section.

[0180] The actuator 30 is likewise arranged outside the internal volume 23. The fluid line 51 is fixed in position via two bearing points 57 arranged at a distance from each other, and the force application point of the actuator 30 is arranged approximately in the middle between the two bearing points 57. The actuator 30 is rigidly connected to the outside of the fluid line 51.

[0181] If the actuator applies a pulling or pushing force to the fluid line 51 during operation, this can cause a radial movement of the fluid line 51 between the two bearing points 57, which can cause a displacement of the fluid line 51 in this section. In this way, the compensation volume 41 can be changed and adapted to compensate for pressure fluctuations. With the reference number 58, the possible displacements of the fluid line 51 when a pushing force is applied by the actuator 30 are specified.

[0182] Figure 8 shows in a side view the basic structure of yet another compensation element 15 according to the invention for active damping of oscillations of a medium 24 according to the embodiment shown in Figure 7. In contrast to the embodiment shown in Figure 7, the side of the fluid line 51 that is located opposite the action side of the actuator 30 is fixed. For this purpose, in this example, a number of bearing points 57 are provided.

[0183] The pressing force of the actuator 30 can move the wall of the fluid line 51 on the side facing the actuator 30 in the direction of the opposite wall of the fluid line 51, so that the compensation volume 41 can be reduced as well. In this embodiment, a higher pressing force by the actuator 30 is required compared to the previously described embodiment with only two bearing points 57. With the reference number 59 the possible displacement of the fluid line 51 when a pressing force is applied by the actuator 30 is specified.

[0184] In these embodiments of the compensation elements 13, 14 and 15, a certain degree of flexibility or elasticity of the fluid line 51 must be taken into account.

[0185] 9 shows in a side view the basic structure of yet another compensation element 16 according to the invention for active damping of oscillations of a medium 24, the hollow body being already provided by a fluid line 51. The volume change takes place in the longitudinal direction of the fluid line 51. In this embodiment of the invention, the fluid line 51 is made flexible in its longitudinal direction.

[0186] For this purpose, a bellows 60 is provided, which allows an axial length change of the fluid line 51. The actuator 30 is arranged axially parallel for this purpose and can bring about a length change of the fluid line 51 in the region of the bellows 60 by means of a corresponding pulling or pushing force, which can likewise bring about a volume change of the compensation volume 41.

[0187] The fluid lines may generally be made from a plastic and may include, for example, an elastomer.

[0188] For applications requiring contact with aggressive or corrosive fluids, such as ultrapure water, and / or working in vacuum or low vacuum, special materials and / or coatings or protective layers are provided that are resistant to the fluids.

[0189] In the case of aggressive or corrosive fluids, such as low-salinity pure water or especially highly pure water, suitable corrosion protection coatings are conceivable, for example based on or including tantalum, inconel, molybdenum or combinations thereof. For example, PVD coatings are also conceivable. For fluid lines, metallic materials, including stainless steel or special steel, may also be suitable.

[0190] Additionally, certain vacuum compatible plastics such as PVDF-HP, ECTFE, or ceramic materials such as SiC may be suitable materials.

[0191] According to the present invention, in another aspect, a method for actively damping vibrations of a medium 24, particularly a fluid, is included, the method comprising the steps of: - providing compensation elements 1, 10, 11, 12, 13, 14, 15, 16; - detecting the total pressure of the medium 24 in the fluid lines 51, 52, 53 by means of a pressure sensor 61, 62, 63, 70; - the inlet pressure difference ΔΡ with respect to a predefined pressure P Ε and - calculating setpoints for the electrical parameters, in particular the voltage, for the actuator 30 and transmitting these setpoints to the actuator 30; - varying the compensation volume 41 by means of the actuator 30 according to a set value for reducing or increasing the compensation volume 41 so that the change in volume allows the pressure difference to be compensated; Includes.

[0192] Another aspect of the invention includes a system 100 for actively damping vibrations in a viscous medium 24, particularly a fluid, configured to implement the method for actively damping vibrations in a medium 24, particularly a fluid, as described above.

[0193] The system 100 comprises a compensation element 1. Figure 4 shows an embodiment of such a system 100 for active damping of vibrations in a viscous medium, exemplarily using only a compensation element 11 according to the invention, where instead of the compensation element 11 other compensation elements 10, 12, 13, 14, 15, 16 can also be used.

[0194] The system 100 comprises fluid lines 51, 52 as supply lines for the purely exemplary illustrated machine 50, installation or device, which are completely filled with a medium 24, for example demineralized water for a cooling circuit. During operation, a total pressure of, for example, 1 Pa, 100 Pa, 1 kPa, 10 kPa or even 100 kPa can be adjusted in the system 100.

[0195] 4 further shows a fluid line 53 extending away from the machine 50. The flow direction is indicated by the numeral 55.

[0196] The compensation element makes it possible to compensate for pressure fluctuations during operation in the system 100, which may be less than or equal to + / - 10 mPa, preferably less than or equal to + / - 5 mPa, particularly preferably less than or equal to + / - 5 mPa.

[0197] In the embodiment of the system 100 for active damping of medium vibrations by means of a compensation element shown in FIG. 4, a nominal flow rate of 2 L / min is specified. In this case, a hose with an internal diameter of 8 mm is used. The nominal pressure is 1.3 bar. The compensation volume is 25 mm 25μm by the actuator 30. This can be used to compensate for pressure surges in the range of, for example, about 50 Pa to 150 Pa, say 100 Pa at 3 Hz.

[0198] For example, at a frequency of 30 Hz, pressure surges of about 1000 Pa can be compensated for by a similar lifting and lowering movement. This is already sufficient to reduce pressure fluctuations in many demanding applications. It is self-evident that the compensation element 1 can be operated with other operating parameters and the stroke area and / or stroke movement can be correspondingly adapted in order to match the available construction space or the selected drive technology.

[0199] This makes it possible to use the invention in or with machines 50, installations or other devices which are highly sensitive to pressure fluctuations and which, for example, require cooling, for example in the field of the semiconductor industry.

[0200] FIG. 10 shows the response behavior of the adjustment according to the invention for comparison using a simple example.

[0201] Reference numeral 91 is used to indicate the desired pressure change over time t.

[0202] The response behavior of a conventional mass flow controller ("MFC") is shown with reference number 92. Over time, relatively large deviations from the setpoint value of the pressure p are shown, which can alternatively also be assumed for the mass flow q.

[0203] Finally, using the reference number 93, the response behavior that can be achieved by the compensation elements 1, 10, 11, 12, 13, 14, 15, 16 is indicated.

[0204] A higher dynamics in the regulation is shown, ie a faster reaching of the target value and a smaller deviation from the target value over time.

[0205] Thus, the desired mass flow rate of the fluid can be adjusted very quickly and accurately, with greatly reduced time-delayed overshoot.

Claims

1. A compensation element for actively damping the oscillations of a medium, in particular a fluid, comprising: a hollow body having an internal volume, a hollow body, wherein a compensation volume is formed in the internal volume, and the hollow body further has at least two openings connecting the compensation volume to the surroundings; at least one actuator capable of enlarging or reducing said compensation volume during operation; A compensation element comprising:

2. The medium is a fluid in gaseous or liquid form, in particular a liquid having a viscosity of at least 1.0·10 at a reference pressure of 0.1 MPa and a temperature of 10° C. ９ Pa, preferably at least 1.5.10 ９ Pa, particularly preferably at least 2.0.10 ９ The compensating element of claim 1 , comprising a liquid fluid having a bulk modulus of 0.1 Pa.

3. 3. Compensation element according to claim 1 or 2, wherein the fluid comprises an aggressive or corrosive gas or liquid, for example demineralized water having a conductivity of 1 to 50 μS / cm, preferably 0.1 to 1 μS / cm, particularly preferably 0.055 to 0.1 μS / cm, in particular ultrapure water as used in the semiconductor industry, or for example also a dielectric liquid.

4. The compensation element of claim 1 , wherein the medium is contained in a fluid line, a line system, a hydraulic section, a pressure line, or a suitable container or vessel.

5. 2. The compensation element according to claim 1, wherein the opening of the compensation element is connected to a fluid line in a force-locking and / or form-locking manner, so that during operation the viscous medium can reach or flow from the fluid line into the compensation volume.

6. The compensating element of claim 1 , wherein the compensating element is non-destructively removable from the fluid line.

7. 2. The compensating element according to claim 1, wherein the compensating element is connectable or connected directly to a machine, piece of equipment or device, the connection preferably being configured to be non-destructively removable.

8. The compensating element of claim 1 , wherein the connection between the compensating element and the fluid line is fluid-tight.

9. 2. The compensation element according to claim 1, wherein a first opening of the hollow body is connected to at least one section of a fluid line that is exposed to pressure fluctuations and / or a second opening of the hollow body is connected to the fluid line.

10. The compensation element of claim 1 , wherein the actuator is disposed outside the interior volume.

11. The compensation element of claim 1 , wherein the actuator is disposed within the interior volume of the hollow body.

12. 2. A compensating element according to claim 1, wherein the actuator is capable of varying the size of the compensation volume during operation, preferably by a movement dependent on pressure fluctuations in a fluid line, preferably by a stroke movement.

13. The compensation element of claim 1 , wherein the actuator comprises a drive device based on magnetic, piezoelectric or electrostatic principles, or a combination thereof.

14. 2. A compensating element according to claim 1, wherein the actuator comprises a drive device with a piezoelectric material, the actuator being preferably protected from aggressive or corrosive fluids by a coating.

15. 2. The compensating element of claim 1, wherein the internal volume is divided into two partial volumes by a flexible diaphragm, thereby forming an additional balance volume in addition to the compensation volume.

16. 16. The compensating element according to claim 15, further comprising a pressure body, which is movable by the actuator and can act on the flexible diaphragm.

17. 2. The compensation element according to claim 1, wherein at least one pressure sensor is preferably provided in at least one opening of the hollow body and / or in the fluid line for determining the total pressure.

18. The compensating element of claim 1 , further comprising at least one force sensor for measuring a force acting on the actuator by the compensating element.

19. The compensation element of claim 1 , wherein the compensation element is adjusted according to a "feedback control" method or according to a "feedforward control" method having a disturbance value input.

20. 20. The compensation element according to claim 19, wherein the flow rate of the medium is taken into account for the adjustment of the compensation element.

21. The compensating element of claim 1 , wherein the hollow body having the interior volume is provided by a fluid conduit.

22. 22. The compensation element of claim 21, wherein a volume change is caused in operation by a substantially radial displacement of the entire fluid line by the actuator, or by displacement of just one wall of the fluid line.

23. 22. The compensating element of claim 21, wherein the fluid line is longitudinally flexible, and the volume change is caused by an axial change in length of the fluid line.

24. A method for active damping of oscillations in a medium, in particular a fluid, comprising: - providing a compensation element; - detecting the total pressure of the medium in the fluid line by means of a pressure sensor; - the inlet pressure difference ΔP relative to a predetermined pressure P Ε and - calculating setpoints for the electrical parameters, in particular the voltage, for the actuators and transmitting these setpoints to the actuators; - varying said compensation volume by means of said actuator based on said set value for reducing or increasing said compensation volume so that the change in volume can compensate for the pressure difference; A method comprising:

25. 25. A system for active damping of vibrations in a viscous medium, in particular a fluid, configured for carrying out a method according to claim 24 and / or comprising a compensation element according to claim 1.

26. A system for controlling the mass flow of a medium, in particular a fluid, comprising a compensation element according to claim 1.

27. 27. The system of claim 26, wherein the system is used for fluid metering or fluid mixing.

28. 10. Machines, installations or other devices, in particular in the semiconductor industry, comprising a compensation element according to claim 1.

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