Compensation element, method and system for the active damping of a medium

Abstract

The disclosure relates to a compensation element for actively damping vibrations of a medium, in particular a fluid. The compensation element comprises a hollow body having an internal volume, with a compensation volume being formed in the internal volume, with the hollow body also having at least two openings which connect the compensation volume to a fluid conduit that is used to supply and discharge the medium, wherein the compensation element is separable from the fluid conduit in a non-destructive manner, and at least one actuator which can increase or decrease the compensation volume during operation.

Claims

1. A compensation element for actively damping vibrations of a medium, comprising: a hollow body having an internal volume, with a compensation volume being formed in the internal volume, with the hollow body further having at least two openings which connect the compensation volume to the environment; and at least one actuator which can increase or decrease the compensation volume during operation.

2. The compensation element of claim 1, wherein the medium comprises a fluid in gaseous or liquid form, in particular a liquid fluid having a compression modulus under normal pressure at 0.1 MPa and at a temperature of 10 C. of at least 1.0.Math.10.sup.9 Pa.

3. The compensation element of claim 2, wherein the fluid comprises aggressive or corrosive gases or liquids, in particular a demineralized water having a conductivity of 1-50 S/cm.

4. The compensation element of claim 1, wherein the medium is accommodated in a fluid conduit, in a piping system, in a hydraulic line, in a pressure line, or in a container or vessel.

5. The compensation element of claim 4, wherein the openings of the compensation element are connected to the fluid conduit in a force-fitting and/or form-fitting manner, wherein the medium can pass or flow from the fluid conduit into the compensation volume during operation.

6. The compensation element of claim 4, wherein the compensation element is separable from the fluid conduit in a non-destructive manner.

7. The compensation element of claim 4, wherein the compensation element can be connected or is directly connected to a machine, an installation component or equipment, wherein the connection is adapted so as to be separable in a non-destructive manner.

8. The compensation element of claim 4, wherein the connection between the compensation element and the fluid conduit is fluid-tight.

9. The compensation element of claim 4, wherein a first opening of the hollow body is connected to at least a portion of the fluid conduit which is exposed to pressure fluctuation, and/or wherein a second opening of the hollow body is connected to the fluid conduit.

10. The compensation element of claim 1, wherein the at least one actuator is arranged outside the internal volume of the hollow body.

11. The compensation element of claim 1, wherein the at least one actuator is arranged inside the internal volume of the hollow body.

12. The compensation element of claim 4, wherein, during operation, the at least one actuator is able to change a size of the compensation volume by a stroke movement, as a function of pressure fluctuations in the fluid conduit.

13. The compensation element of claim 1, wherein the at least one actuator comprises an actuator based on a magnetic principle, piezo principle, or electrostatic principle, or a combination thereof.

14. The compensation element of claim 1, wherein the at least one actuator comprises an actuator including a piezoelectric material, wherein the actuator is protected against aggressive or corrosive fluids, preferably by a coating.

15. The compensation element of claim 1, wherein the internal volume is divided into two partial volumes by a flexible diaphragm, whereby an additional balancing volume is defined in addition to the compensation volume.

16. The compensation element of claim 1, further comprising a pressure body is movable by the at least one actuator to thereby act on the flexible diaphragm.

17. The compensation element of claim 4, further comprising at least one pressure sensor for determining a total pressure, inside at least one opening of the hollow body, and/or inside the fluid conduit.

18. The compensation element of claim 1, wherein at least one force sensor is provided, which measures the force acting on the actuator by the compensation element.

19. The compensation element of claim 1, wherein control of the compensation element is accomplished according to a feedback control procedure or according to feed forward procedure involving feedforwarding of a disturbance variable.

20. The compensation element of claim 1, wherein a flow rate of the medium is taken into account for controlling the compensation element.

21. The compensation element of claim 1, wherein the hollow body has an internal volume is provided by a fluid conduit.

22. The compensation element of claim 21, wherein a change in volume is caused by the at least one actuator through a substantially radial deflection of the fluid conduit as a whole or by deflection of only one wall of the fluid conduit during operation.

23. The compensation element of claim 22, wherein the fluid conduit is adapted so as to be flexible along its longitudinal extension, and the change in volume is caused by an axial change in length of the fluid conduit.

24. A method for actively damping vibrations of a medium comprising the steps of: providing a compensation element; capturing a total pressure of a medium in a fluid conduit using a pressure sensor; determining an inlet side pressure difference P.sub.in to a predefined pressure P; calculating an input value for an electrical parameter, in particular for an electrical voltage, for an actuator, and transmitting the input value to the actuator; and using the actuator to change a compensation volume on a basis of the input value to decrease or increase the compensation volume in such a way that the pressure difference can be compensated for by the change in volume.

25. A system for actively damping vibrations of a viscous medium, configured for performing a method according to the preceding claim.

26. A system for controlling a mass flow rate of a medium, comprising a compensation element according to claim 1.

27. The system of claim 26, wherein the system is used for dosing fluids or for mixing fluids.

28. A machine, installation or other equipment, comprising a compensation element according to claim 1.

Description

IN THE DRAWINGS

[0130] FIG. 1 is a sectional view showing the basic configuration of a compensation element according to the disclosure for actively damping vibrations of a medium;

[0131] FIG. 2 is a sectional view showing the basic configuration of a compensation element according to the disclosure for actively damping vibrations of a medium by way of an embodiment in which the internal volume is divided into a compensation volume and a balancing volume;

[0132] FIG. 3 is a sectional view showing the basic configuration of a compensation element according to the disclosure for actively damping vibrations of a medium by way of an embodiment in which the internal volume is divided into a compensation volume and a balancing volume according to a further embodiment which comprises a force sensor on the actuator;

[0133] FIG. 4 shows an embodiment of a system for actively damping vibrations of a medium using a compensation element;

[0134] FIG. 5 shows the basic structure of a pressure sensor that is particularly suitable for the compensation element;

[0135] FIG. 6 is a side view showing the basic configuration of another compensation element according to the disclosure for actively damping vibrations of a medium, in which the hollow body is already provided by the fluid conduit which is curved at least in sections thereof;

[0136] FIG. 7 is a side view showing the basic configuration of yet another compensation element according to the disclosure for actively damping vibrations of a medium, in which the hollow body is already provided by the fluid conduit and in which the fluid conduit comprises at least one straight section;

[0137] FIG. 8 is a side view showing the basic configuration of yet another compensation element according to the disclosure for actively damping vibrations of a medium, which is based on the embodiment of FIG. 7, comprising continual support of the fluid conduit at least in the straight section;

[0138] FIG. 9 is a side view showing the basic configuration of yet another compensation element according to the disclosure for actively damping vibrations of a medium, in which the hollow body is already provided by the fluid conduit and in which the volume change occurs along the longitudinal extension of the fluid conduit; and

[0139] FIG. 10 shows a comparison of the response behavior of the control according to the disclosure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0140] In the following detailed description of preferred embodiments, the same reference numerals designate substantially similar parts in or on these embodiments, for the sake of clarity. However, to better illustrate the disclosure, the preferred embodiments shown in the figures are not always drawn to scale.

[0141] FIG. 1 is a sectional view showing the basic configuration of an embodiment of a compensation element 1 according to the disclosure for actively damping vibrations of a medium, in particular a fluid, which is illustrated by the curved line 24 in the diagram, for illustrative purposes only.

[0142] The compensation element 1 in the embodiment of FIG. 1 comes in the form of a compensation element 10 comprising an actuator 30 which is arranged in an internal volume 23 of a hollow body 20.

[0143] The following figures show further preferred configurations and embodiments of compensation elements 1 according to the disclosure, which are designated by reference numerals 11, 12, 13, 14, 15, and 16, respectively.

[0144] The compensation element 1, 10, 11, 12, 13, 14, 15 and 16 comprises [0145] a hollow body 20 having an internal volume 23, with a compensation volume 41 being formed in the internal volume 23, with the hollow body 20 further having at least two openings 21, 22 which allow to connect the compensation volume 41 to the environment; and [0146] at least one actuator 30 which is arranged inside the internal volume 23 and allows to increase or decrease the compensation volume 41 during operation.

[0147] When designing the compensation elements 1, 10, 11, 12, 13, 14, 15, and 16, care should be taken to ensure that turbulent flows, which might also be caused by the compensation element itself, are avoided as far as possible.

[0148] The medium 24 may be provided in gaseous or liquid form, and in the present case it comprises a liquid fluid with low compressibility, for example oil or water. The medium 24 is accommodated in a piping system, a fluid conduit, a hydraulic line, a pressure line, or more generally in any suitable container or vessel.

[0149] Fluid conduits 51, 52, 53 are shown merely as examples for illustrative purposes in FIG. 4, which shows an embodiment of a system 100 for actively damping vibrations of a medium 24, in particular a fluid, in which the compensation element 11 is used. Fluid conduit 51 designates the fluid conduit in which the medium 24 is supplied. For this purpose, the fluid conduit 51 may be connected to a pump 54, for example, which is shown in FIG. 4 merely for illustrative purposes.

[0150] The arrangement is such that the pressure fluctuations to be compensated for occur in fluid conduit 51, which therefore represents the supply line in the direction of flow.

[0151] Reference numeral 52 designates the fluid conduit which in the embodiments of FIGS. 1, 2, 3, and 4 is arranged downstream of and leads away from compensation element 11 in the direction of flow. The system 100 of FIG. 4 will be discussed in more detail further below.

[0152] For the sake of clarity, the fluid conduit is not shown in FIG. 1. During operation, the fluid conduit and the compensation volume 41 are filled with the viscous medium 24, in the example with a liquid fluid. In the embodiments, the fluid conduit and the compensation volume 41 are completely filled with the fluid.

[0153] The medium 24 may in particular also comprise low-salt water, pure water, and high-purity water, or in particular ultra-pure water, as required and specified for the semiconductor industry. It is also possible to use the compensation element with fluorine-containing media, in particular fluids, such as fluorine-containing liquids, in particular water.

[0154] More generally, the medium 24 may also comprise aggressive and/or corrosive fluids, i.e. liquids and gases.

[0155] During operation, the openings 21, 22 of the compensation element 10 are connected to the fluid conduit 51, 52 in a force-fitting and/or form-fitting manner. For this purpose, suitable connecting means, e.g. sleeves, screw connections or other suitable fittings are provided to form a force-locking and/or form-locking join between the fluid conduit 51, 52 and the openings 21, 22.

[0156] In the embodiment, these connections are also separable in a non-destructive manner, so that the compensation element can be easily installed and replaced. For actively dampening vibrations, the compensation element is connected to the fluid conduit 51, 52 in a mechanically solid and fluid-tight manner. In the present context, mechanically solid means that the connection is sufficiently resistant to pull-out and vibration during operation, which is ensured by suitable structural dimensions and the choice of the material for the joining partners depending on the specific application.

[0157] In operation, the first opening 21 is used as an inlet or inlet opening for supplying the medium 24, and the further opening 22 is used as an outlet or outlet opening for discharging the medium 24 once the corresponding fluid conduits 51, 52 have been mounted.

[0158] During operation, the opening 22 of the hollow body 20 thus provides the outlet for the medium 24 which can enter the internal volume 23 of the hollow body 20 via the inlet 21. Pressure fluctuations in the fluid conduit 51 supplying the fluid can be at least reduced or ideally fully compensated for by the compensation element. In other words, pressure fluctuations on the inlet side are only passed on to or into the fluid conduit 52 connected to the outlet 22 to a reduced degree or ideally not at all.

[0159] A vibration or oscillation occurring at the inlet 21 with an input amplitude is thereby dampened, so that the output amplitude at the outlet 22 will be lower than the input amplitude. The output amplitude at the output 22 of the compensation element is therefore preferably not more than 50%, 40%, 30%, 10%, or even 1% or less, for example 0.5% or less, in comparison to the input amplitude.

[0160] In FIG. 1, reference numeral 71 indicates the pressure P+P.sub.in applied on the inlet side, and reference numeral 72 indicates the pressure P on the outlet side, for illustrative purposes.

[0161] Pressure fluctuations or pressure surges can occur due to dynamic pressure changes and can be transmitted through the medium 24 in the fluid conduit 51. Excessive pressure surges can cause damage to or in the affected systems 100 or to machines 50, installations or other equipment connected to the system 100, for example in the semiconductor industry sector. The fittings directly connected to the fluid conduit 51, 52, pumps 54, or even foundations may also be damaged by pressure surges.

[0162] At least part of the internal volume 23 of the hollow body 20 is intended to be used as a compensation volume 41, which can be actively enlarged or reduced in order to compensate for or at least minimize pressure fluctuations occurring in the fluid conduit 51, 52. Longitudinal waves in the viscous medium 24 as a result of these pressure surges can be practically absorbed by the compensation volume 41.

[0163] The compensation volume 41 provides the volume that can be specifically and actively changed during operation by the actuator 30 in order to compensate for these pressure fluctuations in the fluid conduit 51, 52. To this end, the actuator 30 can reduce or enlarge the compensation volume 41 by a movement, for example a stroke movement.

[0164] In the embodiment of FIG. 1, the actuator 30 is arranged in the internal volume 23 of the hollow body 20 on the inner wall. This provides for a particularly simple design. The choice of geometry and thus the volume occupied by the actuator 30 are selected in such a way that the compensation volume 41 is given by the remaining volume when the actuator 30 is arranged in its rest position in the hollow body 20.

[0165] In this embodiment of the disclosure, an actuator with a piezoelectric material is provided for the actuator 30, which can operate in liquid media or is resistant to the medium 24.

[0166] For this purpose, the actuator is provided with an anti-corrosion coating, for example based on materials including tantalum, Inconel, molybdenum, or combinations thereof. PVD coatings are also possible. Certain high-purity plastics materials may also be suitable materials, including for example PVDF-HP, ECTFE, or even ceramic materials such as SiC.

[0167] This embodiment allows to dispense with further components, for example to protect the actuator 30. In this way, the compensation element 10 can be kept very simple and compact. The geometry and the material of the actuator 30 are selected such that the movement of the piezoelectric material leads to the desired change in the compensation volume 41 during operation.

[0168] More generally, the actuator 30 may also have other geometries or may be made of other materials and be based on a magnetic principle, piezo principle or electrostatic principle. It may be desirable for the actuator 30 to have a direct and rapid response behavior.

[0169] By applying a voltage, a deformation of the actuator 30 can be caused, which leads to a change in the volume of the actuator 30 inside the hollow body 20. By increasing the compensation volume 41, a positive pressure surge can be absorbed. A reduction in the compensation volume allows to absorb a negative pressure change or a negative pressure.

[0170] In the embodiment of the disclosure shown in FIG. 1, the movement of the actuator 30 at the input side and/or the distance of the actuator 30 to the input side, i.e. in the vicinity of opening 21, is greater than at the output side, i.e. in the vicinity of opening 22. This improves the damping properties.

[0171] In the embodiment, this is achieved by an inclined surface 31 of the body of the piezoelectric material. The inclination as indicated by the angle in FIG. 1 results in a different distance to the two openings 21, 22. The angle is at least 1, preferably at least 5, and particularly preferably at least 10. In the illustrated embodiment, the angle is approximately 5.

[0172] According to a further embodiment of the disclosure, it is intended to divide the internal volume 23 into two partial volumes. FIGS. 2 and 3 are sectional views showing the basic configuration of two compensation elements 11, 12 according to the disclosure for actively damping vibrations of a viscous medium 24 by way of two embodiments in which the internal volume 23 is divided into a compensation volume 41 and a balancing volume 42, in a sectional view.

[0173] Here, a flexible diaphragm 43 is provided, which separates the compensation volume 41, whereby a balancing volume 42 is established in the internal volume 23. The compensation volume 41 is again associated with the space adjacent to the openings, so that it can receive the medium 24 from the fluid conduit 51, 52. The compensation volume 41 inside the hollow body 20 is therefore enclosed by the flexible diaphragm 43 so that the medium 24 cannot escape.

[0174] The desirability of these embodiments is, for example, that the actuator 30 is arranged in a protected manner outside the compensation volume 41 and is thus protected from direct exposure to the medium 24. This makes it possible to use other materials or actuators that are not resistant to the viscous media 24. The compensation volume 41 can again be changed by a respective movement of the actuator 30.

[0175] The flexible diaphragm 43 may, for example, comprise a bellows or be in the form of a bellows, as shown in FIGS. 2 and 3. Materials envisaged for this generally include elastomers that exhibit sufficient elasticity for the required deformations, such as rubber, or else metallic materials such as stainless steel or high-grade steel of appropriate design. When selecting the material, care should be taken to ensure that the required pressure values occurring during operation can be withstood.

[0176] During operation, the compensation volume 41 receives the medium 24, such as a fluid from fluid conduit 51. In the embodiment of the compensation element 11 of the disclosure as shown in FIG. 2, a pressure body 44 is provided, which can be moved by the actuator 30 and can thereby act on the flexible diaphragm 43. The application of force from the actuator 30 to the flexible diaphragm 43 can thereby be improved or simplified.

[0177] The movement of the actuator 30 and thus the size of the compensation volume 41 is controlled by a controller 94 which is monitored and controlled by an electronic computer unit 95.

[0178] The computer unit uses stored programs or value tables to determine an input value for the actuator 30, which is transmitted to the actuator to control the compensation. The controller or another component suitable for controlling can be used for this purpose. The input value relates to at least one electrical parameter, in the embodiment the voltage applied to the actuator 30. The movement of the actuator 30 or its expansion is controlled by the voltage applied. This influences and adjusts the size of the compensation volume 41 accordingly.

[0179] According to a preferred embodiment of the disclosure, the actuator 30 and thus the size of the compensation volume 41 are controlled by the computer unit on the basis of the deviation of the current pressure at the inlet opening 21 from a predefined pressure. Accordingly, a total pressure is present at the inlet opening 21 during operation, which is composed of the predefined pressure P and the pressure difference P.sub.in.

[0180] The total pressure on the inlet side is therefore given by P.sub.in=P+P.sub.in. Alternatively or additionally, the total pressure can also be measured at one or more locations in the fluid conduit 51 on the side which is exposed to the potential pressure fluctuations.

[0181] In FIG. 4, this is schematically illustrated by the two pressure sensors 61, 62, which are associated with the inlet 21 on the one hand and with the fluid conduit 51 on the other hand. If the pressure sensor 62 in fluid conduit 51 is arranged at a sufficient distance from the opening 21, a certain lead time may be resulting, due to the fact that a pressure change occurring downstream during operation will first be detected by pressure sensor 62 and then, with a time delay, by pressure sensor 61. This makes it possible to control the actuator 30 proactively, so that the pressure difference can be compensated for even better. Actuator 30 is controlled in real time. In this way, a pressure difference can be compensated for in real time.

[0182] To this end, the control system is designed with a high bandwidth so that it can respond to very slow changes, for example in the range of less than 0.01 Hz, but also to high frequencies of up to 10 kHz. This can be achieved in both analogue and digital manner. A fundamentally suitable control system can be found in Applicant's document EP 1 840 681 A1 which is hereby included and thus fully incorporated into the subject-matter of the present disclosure in its entirety.

[0183] Using stored algorithms, the computer unit determines, based on the data from the pressure sensors 61, 62, an input value for the electrical voltage to be applied to the actuator 30.

[0184] Instead of permanently programmed algorithms for the controlling or adjusting of the compensation element, it is also envisaged in a further refinement of the disclosure to use methods of machine learning or artificial neural networks to support the controlling.

[0185] This can be helpful, for example, if a plurality of compensation elements comprising a plurality of actuators are to be controlled and regulated jointly, and/or if a plurality of compensation elements are connected together to form a larger, complex group or network of fluid conduits. Then, in yet another refinement of the disclosure, further data or parameters from other installations, machines or systems connected to the network can also be taken into account for the controlling or adjustment strategy, for example room temperatures or temperatures at or in the installations or machines 50.

[0186] PID controllers can also be used for the controlling.

[0187] In this way, the actuator control can be transferred to a self-learning mode and, for example, recognize certain patterns in the pressure changes so that compensation can be accomplished even more quickly and precisely. For this purpose, pressure sensors may also be arranged at several locations in the fluid conduit 51, 52, 53, for example upstream of pumps, valves or similar fittings, so that information about pressure changes can be captured very early on.

[0188] Thus, in one embodiment of the disclosure it is also intended to take into account the flow rate of the medium 41, in particular of the fluid, for controlling the compensation element.

[0189] The actuator 30 performs a movement adapted to the pressure deviation P.sub.in, so that the pressure difference is reduced or ideally completely compensated for inside the hollow body 20 by adjusting the compensation volume 41. In this way, a pressure fluctuation occurring in fluid conduit 51 can be minimized or ideally completely compensated for, so that the following applies to the total pressure P.sub.out at outlet opening 22: P.sub.out=P, or ideally P.sub.out=P, and hence P.sub.in0 Pa, or P.sub.in=0 Pa.

[0190] In one embodiment of the disclosure, controlling is accomplished according to the feedback control procedure or as closed-loop control. The required movement of the actuator 30 is determined by suitable filters in a control system. When designing the control system, non-linear and/or hysteresis effects of the actuator 30, such as of the piezoelectric material, are already taken into account in order to prevent overshooting, i.e. excessive damping.

[0191] Alternatively or in addition to this feedback control, it is also possible, in a further embodiment of the disclosure, to integrate into the control a feed forward procedure or feedforward of a disturbance variable in order to increase the effectiveness even further. For this purpose, the pressure fluctuation is also measured downstream, i.e. in the embodiment in the fluid conduit 52 which is connected to the outlet opening 22 of the hollow body 20. In FIG. 4, a further pressure sensor 63 is shown, merely as an example.

[0192] While in these embodiments the pressure sensors are associated with the components carrying the medium 24, i.e. inlets 21, 22 or fluid conduits 51, 52, FIG. 3 shows an embodiment of a compensation element 12 which is based on the embodiment of FIG. 2, but additionally comprises a force sensor or force transducer 32 on the actuator 30, and which is therefore arranged between the actuator 30 and the compensation volume 41.

[0193] In the embodiment, the force sensor 32 is arranged between the actuator 30 and the pressure plate 44. In this embodiment of the disclosure, the pressure force acting on the actuator 30 is used as a control parameter, as the leading control variable. The force difference F is given as: F=P.sub.in*A, where A is the size of the exposed surface. In this case, the objective of the control is to minimize the force difference acting on the actuator 30 or, ideally, to compensate for it completely, so that: F0 N, or F=0 N.

[0194] In this case, the compensation volume 41 is changed during operation as a function of the pressure force acting on the actuator 30. The desirability of this procedure is that no pressure sensor is required in or on the fluid conduit 51, 52.

[0195] In one embodiment of the disclosure, a pressure sensor 70 is provided for measuring the total pressure, which can be used particularly well together with the compensation element. Its basic configuration is schematically shown in FIG. 5.

[0196] Pressure sensor 70 captures a relative pressure in the fluid conduit 51, by evaluating the pressure difference on two sides of the sensor element. With the same mean pressure on both sides it is possible to measure fluctuations in the mPa range.

[0197] One input of the pressure sensor 70 is connected directly to the fluid conduit 51 via a feed line 73. This ensures that all pressure fluctuations can be detected on this side.

[0198] From a certain distance downstream in the fluid conduit 51, the pressure is fed back to the second input of the pressure sensor 70. By using a capillary tube 74 of appropriate length and appropriate diameter and utilizing the volume on the pressure sensor 70, it can be ensured that pressure fluctuations above a particular frequency cannot reach this side of the pressure sensor. In this way, a low-pass filter is provided, with a cutoff frequency that is determined by the geometry of the capillary passage 74 and the volume of the pressure sensor 70. This design means that the pressure sensor 70 does not measure the constant pressure, but only detects the fluctuations above the cutoff frequency of the low-pass filter. This principle can be used for the feed-forward procedure.

[0199] In this way it is possible to measure fluctuations or differences in the total pressure with an accuracy of 0.1 Pa or better, preferably 0.05 Pa, or even 0.01 Pa, even at a high pressure, for example at a pressure of 50 kPa or more, preferably 100 kPa or more.

[0200] Other suitable pressure measurement techniques may include laser interferometers for measuring pressure differences radially and/or axially in a fluid conduit, or else acceleration sensors.

[0201] Particularly suitable for the disclosure are measuring techniques or sensors that enable measurement of the pressure difference.

[0202] FIG. 6 is a side view showing the basic configuration of another compensation element 13 according to the disclosure for actively damping vibrations of a medium 24, in which the hollow body is already provided by the fluid conduit 51. The latter is curved at least in sections thereof.

[0203] The internal volume 32 of the fluid conduit 51, 52 thus provides the compensation volume 41 which can be increased or decreased during operation by the actuator 30. In this embodiment, the actuator 30 is arranged outside the internal volume 32. The fluid conduit 51 is curved at least in sections thereof, or is designed with a curvature.

[0204] The actuator 30 is arranged between two opposing curved sections 56 of the fluid conduit 51 here, and is firmly 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 conduit 51, so that these sections 56 can be pulled together or pushed apart. For this purpose, further force transfer components 34 such as rods or tubes may be provided.

[0205] In this way, the size of the internal volume 32 provided by the fluid conduit 51, 52 can be changed. It will be appreciated that the fluid conduit 51 is designed so as to exhibit adequate resiliency and can be made from an elastic plastics material, for example. In the embodiment, a hose is provided.

[0206] As shown in the embodiment, the curvature may be in the form of a full circle or a complete loop of the fluid conduit 51. The effect can be increased even further if more than one loop is provided, for example two, three or four loops.

[0207] FIG. 7 is a side view showing the basic configuration of yet another compensation element 14 according to the disclosure for actively damping vibrations of a medium 24, in which the hollow body is again already provided by the fluid conduit 51. Instead of a curved section, the fluid conduit 51 according to this embodiment comprises at least one straight section.

[0208] The actuator 30 is again arranged outside the internal volume 23. The fluid conduit 51 is fixed by two spaced-apart support points 57, and the actuator 30 is arranged with its force application point approximately centrally between these two support points 57. The actuator 30 is firmly connected to the outside of the fluid conduit 51.

[0209] When the actuator exerts a pulling force or a pushing force on the fluid conduit 51 during operation, this can cause the fluid conduit 51 to move radially between the two support points 57, which can cause a deflection of the fluid conduit 51 in this section. In this way, the compensation volume 41 can be changed and adjusted in order to compensate for a pressure fluctuation. A potential deflection of the fluid conduit 51 when a pushing force is applied by the actuator 30 is indicated by reference numeral 58, for illustrative purposes.

[0210] FIG. 8 is a side view showing the basic configuration of yet another compensation element 15 according to the disclosure for actively damping vibrations of a medium 24, which is based on the embodiment of FIG. 7. In contrast to the embodiment of FIG. 7, the side of the fluid conduit 51 opposite to the side on which the actuator 30 engages is fixed. In the embodiment, a plurality of support points 57 are provided for this purpose.

[0211] A pushing force exerted by the actuator 30 will enable to move the wall of the fluid conduit 51 on the side facing the actuator 30 towards the opposing wall of the fluid conduit 51, so that the compensation volume 41 can also be decreased. In this embodiment, a higher pushing force will be required by the actuator 30 compared to the aforementioned embodiment which only has two support points 57. A potential deflection of the fluid conduit 51 when a pushing force is applied by the actuator 30 is indicated by reference numeral 59, for illustrative purposes.

[0212] In these embodiments of the compensation element 13, 14, and 15, a certain flexibility or resiliency of the fluid conduit 51 should be ensured.

[0213] FIG. 9 is a side view showing the basic configuration of yet another compensation element 16 according to the disclosure for actively damping vibrations of a medium 24, in which the hollow body is already provided by the fluid conduit 51, and in which the volume change occurs along the longitudinal extension of the fluid conduit 51. In this embodiment of the disclosure, the fluid conduit 51 is designed so as to be flexible along its longitudinal extension.

[0214] For this purpose, a bellows 60 is provided such that an axial change in the length of the fluid conduit 51 is made possible. The actuator 30 is arranged parallel to the axis for this purpose, and is able to cause a longitudinal change in the fluid conduit 51 within the range of the bellows 60 by respective tensile or compressive forces, which can also cause a change in the volume of the compensation volume 41.

[0215] The fluid conduit may generally be made of plastics material and may also include elastomers, for example.

[0216] For applications that require contact with aggressive or corrosive fluids, such as ultra-pure water, and/or that operate in a vacuum or deep vacuum, special materials and/or coatings or protective layers that are resistant to the fluids are available.

[0217] In the case of aggressive or corrosive fluids such as low-salt water, pure water, or in particular ultra-pure water, suitable anti-corrosion coatings are considered, for example based on or comprising tantalum, Inconel, molybdenum, or combinations thereof. PVD coatings are also conceivable, for example. Metallic materials including stainless steel or high-grade steel may also be suitable for the fluid conduit.

[0218] Certain plastics materials, for example those that are suitable for use in vacuum, can also constitute useful materials, including PVDF-HP, ECTFE, for example, or even ceramic materials such as SiC.

[0219] In a further aspect of the disclosure, the disclosure also encompasses a method for actively damping vibrations of a medium 24, in particular a fluid, comprising the steps of: [0220] providing a compensation element 1, 10, 11, 12, 13, 14, 15, 16; [0221] capturing the total pressure of a medium 24 in a fluid conduit 51, 52, 53 using a pressure sensor 61, 62, 63, 70; [0222] determining the inlet side pressure difference P.sub.in to a predefined pressure P; [0223] calculating an input value for an electrical parameter, in particular for the electrical voltage, for an actuator 30, and transmitting the input value to the actuator 30; [0224] using the actuator 30 to change the compensation volume 41 on the basis of the input value to decrease or increase the compensation volume 41 in such a way that the pressure difference can be compensated for by the change in volume.

[0225] Also encompassed, in a further aspect of the disclosure, is a system 100 for actively damping vibrations of a viscous medium 24, in particular a fluid, which system is configured for carrying out a method for actively damping vibrations of a medium 24, in particular a fluid, as described above.

[0226] The system 100 comprises a compensation element 1. FIG. 4 shows an embodiment of such a system 100 for actively damping vibrations of a viscous medium, which comprises a compensation element 11 according to the disclosure merely by way of example, while other compensation elements 10, 12, 13, 14, 15, 16 may likewise be used instead of the compensation element 11.

[0227] System 100 comprises a fluid conduit 51, 52 as a supply line for a machine 50, installation or equipment merely sketched as an example, which is completely filled with a medium 24, in this example with 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 set in the system 100.

[0228] Also shown in FIG. 4 is a fluid conduit 53 which leads away from the machine 50. The flow direction is indicated by reference numeral 55.

[0229] The compensation element allows to ensure that a pressure fluctuation in this system 100 during operation can be +/10 mPa or less, preferably +/5 mPa or less, most preferably +/5 mPa or less.

[0230] For the embodiment of a system 100 as shown in FIG. 4 for actively damping vibrations of a medium using a compensation element, a flow rate of nominally 2 L/min is intended, and a hose with an inner diameter of 8 mm is used here. Nominal pressure is 1.3 bar. The compensation volume is provided with a stroke surface area 33 of 25 mm.sup.2, which can be moved by +5 m by the actuator 30. This allows, for example, to compensate for a pressure disturbance in a range of approximately 50 to 150 Pa, for example 100 Pa, at 3 Hz.

[0231] At a frequency of 30 Hz, for example, pressure surges of about 1000 Pa can be compensated for with a similar stroke movement. This is already sufficient to reduce pressure fluctuations in many demanding applications. It will be appreciated that the stroke surface area and/or the stroke movement can be adapted accordingly in order to be able to operate the compensation element 1 with other operating parameters and to adapt it to the available installation space or the selected drive technology.

[0232] The disclosure thus makes it possible to be used on or with machines 50, installations or other equipment which are highly sensitive to pressure fluctuations and which need to be cooled, for example, such as in the semiconductor industry sector.

[0233] FIG. 10 shows a comparison for the response behavior of the control according to the disclosure by way of a simple example.

[0234] Reference numeral 91 indicates a desired pressure change over time t.

[0235] Reference numeral 92 indicates the response behavior of a prior art mass flow controller (MFC). Over time, rather significant deviations from the setpoint value for the pressure p are evident in some instances, and as an alternative, a mass flow rate q can also be assumed here.

[0236] Finally, reference numeral 93 indicates the response behavior that can be achieved using the compensation element 1, 10, 11, 12, 13, 14, 15, 16.

[0237] What is evident here is the higher dynamics in the control, i.e. a faster reaching of the setpoint value, as well as a lower deviation from the setpoint value over time.

[0238] Thus, a desired mass flow rate of a fluid can be adjusted very quickly and precisely, delayed overshooting is significantly reduced.