COMPENSATION ELEMENT, METHOD AND SYSTEM FOR ACTIVELY DAMPENING A MEDIUM

Description

[0001] The present invention relates generally to a compensation element, a method, and a system for actively damping vibrations of a medium, in particular a fluid. The compensation element can, for example, compensate for pressure fluctuations in piping systems.

[0002] The transmission of vibrations through media, especially fluids, has long been a problem. Particularly with incompressible liquids, vibrations are only minimally damped during propagation, allowing them to travel long distances. This affects, for example, liquid-filled piping systems to which sensitive machinery and equipment are connected, and which therefore place high demands on maintaining constant pressure within the system. Various solutions have been developed to reduce potential pressure fluctuations.

[0003] Expansion vessels, for example, are known as quasi-flexible compensators that allow the pipe volume in closed piping systems to increase when pressure rises and conversely, to decrease when pressure drops. However, this can also lead to a decrease in pressure downstream of the compensator or vessel.

[0004] In certain applications, such as precision instruments that require very high levels of constant pressure, relatively large expansion vessels may be necessary to effectively compensate for pressure changes. Pressure changes, especially with incompressible fluids like water, can cause vibrations that are often reflected in piping systems and thus transmitted over long distances. This can impair or even damage sensitive equipment, such as electron beam generators, or sensors. Volume changes can also occur, which can adversely affect connected devices or systems.

[0005] The pressure changes can continue to cause deformations, which can lead to further impairments or even damage.

[0006] Against this background, such solutions are more commonly used for applications with less stringent requirements. For example, these expansion vessels are used to maintain constant pressure in a heating circuit or to prevent water hammer in a house's water system. They are typically tuned to a specific frequency range.

[0007] Another solution involves using a combination of Helmholtz-like resonators in the flow to compensate for, or at least reduce, pressure fluctuations at different frequencies. The resonators are selected according to the volume to be damped and the pipe lengths in order to adjust the frequency response.

[0008] DE 10 2013 217 119 A1 describes such a damping element for damping vibrations in a pressure line, using the clutch of a motor vehicle as an example. A hollow cylindrical damper operating on the basis of a Helmholtz resonator is proposed, which includes a double-walled housing to form a damper volume. Such resonators are typically precisely tuned to a specific frequency range, which can then be effectively filtered. For a broader frequency spectrum, the damper volume must be increased.

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

[0010] Such damping elements may be reliable, but are quite complex in their construction and generally relatively large compared to, for example, the pipe diameter.

[0011] Furthermore, they must be individually tailored to the volume and the piping system.

[0012] EP 0 679 832 B1 describes a device for reducing pressure pulsations in a hydraulic line, wherein a movable wall is provided in a compensating volume connected to the line.

[0013] WO 2019 / 037840 describes a method for pulsation damping in a fluid-carrying system. It is designed to regulate the pressure in the space between the fluids to a minimum value for the fluid pressure pulsation amplitude.

[0014] GB 2 590 667 A describes a pump outlet coupling comprising an outlet pipe extending between the inlet and outlet, the outlet having a throttle whose cross-sectional area can vary. The throttle can consist of a removable insert or an interchangeable throttle. The throttle can be actuated in response to a measured temperature, pressure, and / or flow rate, and / or in response to the user's desire to reduce noise or pump downtime. The piping can have sections with different cross-sectional areas. The inlet can have a smaller cross-sectional area than an adjacent section of the piping and can have a section extending from the piping. The piping can have at least one bent and / or flexible section.

[0015] EP 0 886 262 A2 describes a method for reducing noise of sound-carrying media in pipelines by generating an anti-sound, wherein the anti-sound is generated by one or more segments of the pipe wall, and wherein the segments consist of piezoelectric foils which are controlled for anti-sound generation by means of a control unit.

[0016] Other damping systems operate with an electro- or magnetorheological fluid, as is known, for example, from the applicant's patent EP 2 759 735 B1. The damping can be individually and continuously adjusted via a control loop.

[0017] This is comparatively complex and can also be time-critical due to a delayed response time.

[0018] Therefore, a compensation or damping element that does not have these disadvantages would be desirable.

[0019] The compensation or damping element should be as small as possible.

[0020] Furthermore, it would be advantageous if the compensation or damping element could be adapted, at least partially, to the specific characteristics of the volume and the piping system, so that a special compensation or damping element would not have to be provided for every volume or every piping system.

[0021] Easy installation on the existing piping system would also be advantageous.

[0022] Furthermore, the compensation or damping element should be usable with a wide variety of media, especially different fluids. These include, for example, media such as ultrapure water (UPW), which can be used in the semiconductor industry and is highly corrosive, or other aggressive and / or corrosive media, or liquids such as dielectric fluids, e.g., fluids with a high fluorine content.

[0023] The inventors have taken on this task.

[0024] This problem is solved surprisingly simply by a compensation element for the active damping of vibrations of a medium, in particular a fluid, as well as by a method and a system for the active damping of vibrations of a medium, in particular a fluid, according to one of the independent claims. Preferred embodiments and further developments of the invention can be found in the respective dependent claims.

[0025] The invention therefore relates to a compensation element for the active damping of vibrations of a medium, comprising, among other things, a hollow body having an internal volume, wherein a compensation volume is formed in the internal volume, wherein the hollow body further has at least two openings which can connect the compensation volume to the environment, and at least one actuator which can increase or decrease the compensation volume during operation.

[0026] According to a preferred embodiment of the invention, the actuator can be arranged in the inner volume, but also outside of it.

[0027] The medium can, in particular, comprise a fluid which may be in gaseous or liquid form. The compensation element can be used particularly advantageously in conjunction with slightly compressible or incompressible fluids, especially liquids. These are understood to be fluids which, at normal pressure of 0.1 MPa and a temperature of 10 °C, have a bulk modulus of at least 1.0 × 10⁹ Pa, preferably at least 1.5 × 10⁹ Pa, and most preferably at least 2.0 × 10⁹ Pa. Fluids particularly suitable for the invention therefore include oil, water, or oil-water mixtures.

[0028] In one embodiment of the invention, it is also provided for the use of demineralized water as the medium, i.e., the operation of the compensation element in conjunction with purified and / or demineralized liquids. Demineralized water can be classified according to its conductivity into purified, low-salt water with a conductivity of 1-50 µS / cm ("Purified Water"), pure water with a conductivity of 0.1-1 µS / cm ("Pure Water"), and ultrapure water with a conductivity of 0.055-0.1 µS / cm ("Ultrapure Water"). The invention is particularly suitable for operation with purified, pure, or ultrapure water, or "Ultrapure Water" (UPM), as required and used in the semiconductor industry. With these liquids, other parameters and quantities can also be controlled and reduced, for example, total organic carbon (TOC), particles, or dissolved gases.The invention therefore also relates in one aspect to a compensation element which is designed for use with low-salt water, pure water and highly purified water.

[0029] In a further embodiment of the invention, it is also provided for the use of technical or dielectric fluids, in particular liquids, for example fluorine-containing fluids, such as fluorine-containing liquids. In general, the medium can comprise aggressive or corrosive liquids or gases.

[0030] The medium may, for example, be contained in or guided in a piping system, a fluid line, a hydraulic line, a pressure line or generally in any other suitable container or vessel.

[0031] For the sake of simplicity, the term "fluid line" will be used below, but this also includes any hydraulic section, pressure line, piping system, or generally any other container or vessel suitable for holding a medium, particularly a fluid. According to the invention, this fluid line is at least partially filled with the medium to be dampened, particularly a fluid, during operation.

[0032] In certain embodiments, the hollow body can also be provided by the fluid line itself. In other words, the internal volume of a section of a fluid line can serve as a compensating volume.

[0033] The openings of the compensating element can be connected to the fluid line by force-fit and / or form-fit. Suitable connecting elements or fittings can be provided to create a force-fit and / or form-fit connection between the fluid line and the openings. These are advantageously selected to allow for easy assembly and, ideally, non-destructive disassembly. This facilitates simple installation of the compensating element and eliminates the need for welding, which can also be beneficial with regard to potential deformation or cracking. In the event of a defect, the compensating element can be easily exchanged and replaced.

[0034] According to a further embodiment of the invention, it is also possible and conceivable to connect the compensation element directly to a system component or device that is to be cooled and / or damped, for example, with water. Naturally, several compensation elements can also be provided on a system or device in order to cool a larger area or region, for example.

[0035] The compensating elements installed in this way can be connected to the fluid line, and this is possible not only in linear structures but also in network structures. In this way, for example, larger areas can be cooled particularly effectively.

[0036] The connections to the fluid line can also be made after the compensation element has been installed. The invention therefore also relates, in one aspect, to a compensation element that can be directly connected to, or is connected to, a system component or device. It is understood that suitable fastening means can be provided on the compensation element for this purpose. Fastening can also be achieved, for example, by adhesive bonding. In other embodiments, however, it may also be advantageous if the connection is designed to be detachable without damage.

[0037] For active vibration damping, the compensation element can be rigidly and fluid-tightly connected to the fluid line. Fluid-tight means that no medium or fluid escapes from the connection points between the compensation element and the fluid line during regular operation, i.e., under predetermined pressure or temperature conditions.

[0038] The section of the fluid line exposed to potential pressure fluctuations can be connected to a first opening of the hollow body. Advantageously, the second opening is also connected to a fluid line.

[0039] The first opening is hereinafter also referred to as the inlet or inlet opening and the second opening as the outlet or outlet opening, whereby this distinction is made with regard to the functionality of the openings or the fluid lines associated with them and not with regard to their technical design.

[0040] The second opening of the hollow body thus provides the outlet for the medium, which can enter the internal volume, particularly the compensation volume, of the hollow body via the inlet. Pressure fluctuations in the fluid line on the inlet side can be at least reduced or preferably compensated for by the compensation element. In other words, pressure fluctuations on the inlet side are only reduced or ideally no longer transmitted on the outlet side.

[0041] Pressure fluctuations refer specifically to pressure surges or pressure differences that can occur due to dynamic pressure changes in a viscous medium within a fluid line. Examples include pressure increases in a pipeline that can occur when a shut-off valve is rapidly opened or closed, or the starting and stopping of pumps within the fluid line. In certain cases, dynamic pressure changes are also referred to as pressure hammer or water hammer.

[0042] The magnitude of a pressure surge varies and can depend on several factors, such as the volume of the fluid line or the compressibility of the medium. Generally, the magnitude of a pressure surge is higher for liquid fluids, which are less compressible, than for gaseous media, where the fluid's inertia also plays a role.

[0043] Pressure changes are transmitted by pressure waves, which, within the scope of the invention, are also referred to as pressure fluctuations. These are longitudinal waves. Decelerating or accelerating a fluid in a fluid line requires a certain force, which can be determined using Newton's second law. These pressure changes or fluctuations can trigger vibrations, particularly in incompressible fluids such as water, which can affect the fluid line.

[0044] Vibrations can also be transmitted through the fluid line, even over longer distances, so damping may be necessary here as well.

[0045] To decouple or dampen vibrations in the fluid line or the system, or even individual fittings, components such as rubber or rubber-like components, corrugated components, U-tubes or bellows can also be used, provided the boundary conditions allow this.

[0046] These vibrations of the fluid line can lead to several undesirable effects. For example, deformations and volume changes can alter the distance to a system or device being cooled, potentially causing stresses within the system or device. This, in turn, can lead to deformations of the area being cooled.

[0047] Pressure surges can also cause damage to or within the affected systems. For example, sensitive equipment, such as electron beam devices, or sensors can be impaired or even damaged.

[0048] In the worst-case scenario, pipelines can burst, or pipeline supports can be damaged. Fittings, pumps, and even foundations connected to the fluid line can also be damaged by pressure surges. The problem is that minor damage is often not immediately visible, which can lead to further damage.

[0049] Pressure surges or fluctuations can be particularly critical in highly sensitive facilities, machines or systems, such as systems or devices in the field of nanotechnology or electron beam devices with, for example, highly sensitive optical equipment.

[0050] This applies, for example, to water cooling circuits to which machines, systems, or equipment in the semiconductor industry are connected, and which are highly sensitive to pressure fluctuations in the water cooling circuit or contain sensitive components. Here, pressure fluctuations well below 1 Pa, for example, below 0.1 Pa or even below 0.01 Pa, can lead to deviations that can disrupt or affect processes, or require accuracy can no longer be met, and / or damage can occur.

[0051] Because water has a high compression modulus, which is significantly higher than that of oil, for example, it is considered almost incompressible, so that pressure changes can propagate rapidly and with great force in the fluid line.

[0052] The compensation element according to the invention serves to reduce or compensate for pressure surges in fluid lines, so that pressure fluctuations or vibrations in the fluid system can be dampened, reduced, or ideally completely balanced. The compensation element according to the invention thus makes it possible to maintain the pressure in the fluid line at a predetermined level with a very low deviation from this value.

[0053] In this context, damping can be understood as the removal of pressure-related energy from the closed fluid circuit. It is more accurately described as a reduction of pressure fluctuations within the medium than as damping in the sense of mechanical vibrations. Removing this energy requires work, which is not entirely efficient and generates heat. Therefore, the design of the compensation element should ensure that no significant heat is transferred to the medium from which the pressure fluctuations are reduced.

[0054] Ideally, this results in the input amplitude of the oscillation decaying to zero at the output, thus achieving complete compensation of the oscillation. However, according to the invention, damping can also be understood as reducing the input amplitude of the oscillation to be damped by at least 50%, preferably at least 60%, and particularly preferably at least 70%, or even 90%, 99%, or more, for example, 99.5% or more. The output amplitude at the output of the compensation element is therefore preferably no more than 50%, 40%, 30%, 10%, or even 1% or less, for example, 0.5% or less, with respect to the input amplitude. Furthermore, according to the invention, this damping is intended to occur in the shortest possible time.

[0055] This concerns a frequency range from approximately 0.01 Hz to approximately 20 kHz, preferably from 0.1 Hz to 100 Hz.

[0056] While a mass flow controller (MFC) can regulate a mass flow rate to a setpoint, they typically lack the required dynamic range to control and regulate very small or very large mass flow rates due to their relatively slow response time.

[0057] When switching on, a time-delayed overshoot can occur, i.e., the setpoint can be exceeded or overdriven, but also undershot or underdriven, which is unfavorable for the invention, which involves very sensitive processes.

[0058] The compensation element according to the invention can therefore also serve in a further aspect of the invention to provide a very precise constant mass flow of the fluid from switching on to switching off, whereby the inertia during switching on and off is low.

[0059] In accordance with the invention, a portion of the internal volume of the hollow body, in particular the compensation volume, can be used for this purpose, which can be actively enlarged or reduced in order to compensate for or at least minimize pressure fluctuations occurring in the fluid line.

[0060] The compensation volume is the volume that can be actively and selectively changed by the actuator during operation to compensate for pressure fluctuations in the fluid line. According to the invention, the compensation volume can be reduced or increased by an active movement of the actuator, such as a lifting motion. In other words, the actuator is designed to change the compensation volume during operation and thus compensate for pressure fluctuations in the fluid line. The actuator can be based on a magnetic, piezoelectric, or electrostatic principle. Such actuators are characterized by a direct and rapid response for their intended or suitable application and can also be controlled very precisely in their mechanical movement by appropriate electrical control.Further developments of the invention also envision combinations, whereby actuators based on different principles can be combined to expand the range of applications.

[0061] In general, applying a voltage, which can be regulated by a controller, causes the actuator to deform, leading to a change in the actuator's volume within the hollow body. Increasing the compensation volume remaining within the hollow body can effectively absorb a positive pressure surge. Conversely, decreasing the compensation volume can absorb a negative pressure change.

[0062] In one embodiment of the invention, it is provided that an actuator with a piezoelectric material is selected for the actuator, which can operate in liquid fluids or is resistant to liquid fluids.

[0063] According to one embodiment of the invention, the actuator can be protected to enable operation in conjunction with or in contact with aggressive or corrosive fluids, in particular ultrapure water and / or fluorine-containing fluids. For example, coatings or protective layers resistant to these fluids can be provided. In the case of aggressive or corrosive fluids such as low-salt, pure, or especially ultrapure water, suitable corrosion protection coatings are envisaged, for example, those based on or comprising tantalum, Inconel, molybdenum, or combinations thereof. PVD coatings are also conceivable. It is understood that the other fittings and / or system components should also be protected accordingly.

[0064] In this way, it is possible to arrange the actuator directly within the internal volume. The advantage of this embodiment of the invention is that the piezoactive material or the piezo actuator can be placed directly in the cavity, and no additional internal components are required to protect the actuator, since it can come into direct contact with the fluid from the fluid line. This allows the compensation element to be kept very simple and compact.

[0065] By appropriately selecting the geometry of the piezoelectric material and arranging it within 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 in the compensation volume. According to one embodiment of the invention, the compensation volume can be the volume that results when the actuator is in a rest position within the internal volume of the hollow body, i.e., in its normal size without any electrical influence.

[0066] In a further development of the invention, the movement of the actuator is greater at the inlet side of the hollow body than at the outlet side. This improves the damping or absorption of vibrations, resulting in overall better performance. This can be achieved, for example, by arranging the openings on one side of the hollow body and the piezoelectric material inside the hollow body on the opposite side, with the distance of the piezoelectric material to the inlet opening being smaller than to the outlet opening. With a rectangular cross-sectional shape of the hollow body, this can be achieved very simply, for example, by angling the surface of the piezoelectric material accordingly towards the openings. The inclination can result in an angle α, which is preferably at least 1°, more preferably at least 5°, and particularly preferably at least 10°.

[0067] In a further preferred embodiment of the invention, the internal volume is divided into two partial volumes by means of a flexible membrane, so that in addition to the compensation volume, a second volume, hereinafter also referred to as the equalization volume, can be formed. The compensation volume is again located in the space adjacent to the openings, so that it can receive the medium from the fluid line. The compensation volume within the hollow body is thus enclosed by the flexible membrane to prevent the medium from escaping. Advantageously, the actuator can also be arranged outside the compensation volume.

[0068] The flexible membrane can, for example, encompass a bellows or be designed as a bellows. Suitable materials include elastomers, which possess sufficient elasticity for the required deformations.

[0069] In applications under vacuum or deep vacuum, however, certain materials can be problematic and therefore cannot be used, especially in conjunction with aggressive or corrosive media. For this reason, the invention also utilizes other materials, including rigid, less elastic materials in suitable designs, particularly metallic materials such as stainless steel. During operation, the compensation volume can accommodate the medium, such as a fluid from the fluid line.

[0070] The advantage of such an arrangement lies in the fact that the actuator is protected from the medium by the flexible membrane. This makes it possible to use other materials or actuators that are not resistant to the fluid in the line or cannot be designed to be. The compensation volume can, in turn, be changed by moving the actuator accordingly, as described above.

[0071] In a further development of the invention, a pressure element is provided which can be moved by the actuator and thereby act on the flexible membrane. This improves or simplifies the force transmission from the actuator to the flexible membrane.

[0072] The actuator's movement, and thus the size of the compensation volume, can be controlled by a controller, which can be monitored and regulated by an electronic computer unit. The computer unit can determine a target value for the actuator and transmit it to control the compensation. This allows the voltage applied to the actuator to be controlled in order to change the size of the compensation volume.

[0073] According to one embodiment of the invention, the actuator, and thus the size of the compensation volume, is controlled by the computer unit based on the deviation of the current pressure at the inlet opening from a predetermined pressure. A total pressure can therefore be established at the inlet opening, which is composed of the predetermined pressure P and the pressure difference ΔP E.

[0074] The total inlet pressure is therefore calculated as PE = P + ΔP E. Alternatively or additionally, the total pressure can also be measured at one or more points in the fluid line on the side that is exposed to potential pressure fluctuations.

[0075] For this purpose, appropriate sensors or pressure gauges may be installed in the inlet opening of the hollow body and / or in the fluid line, which will be discussed in more detail below.

[0076] The computer unit can therefore be provided with data on the pressure conditions prevailing in the fluid line, whereupon it can calculate a target value for the actuator's electrical voltage. This target value corresponds to the voltage to be applied to the actuator to cause it to change the volume of the compensation volume in a way that can equalize the pressure difference. In this way, the actuator can perform a movement adapted to the pressure deviation ΔP E, which, by changing the compensation volume in the hollow body, reduces or ideally completely eliminates the pressure difference. Thus, pressure fluctuations occurring in the fluid line can be minimized or, ideally, completely compensated, so that the total pressure at the outlet PA is approximately: PA = ≈ P or, ideally, PA = P.

[0077] In other words, in this embodiment of the invention, the compensation volume is changed by a corresponding movement of the actuator based on the pressure fluctuation in the fluid line in such a way that the predetermined value for the pressure is present at the outlet of the hollow body and the pressure fluctuation is thus zero or almost zero.

[0078] The compensation element can be controlled using a feedback control method to reduce pressure fluctuations. The required actuator movement is determined by suitable filters in the control system. When designing the control system, it is advantageous to consider nonlinear and / or hysteresis effects of the actuator, such as those of the piezoelectric material, to prevent overshoot, i.e., excessive damping.

[0079] In a further development of the invention, it is provided that the flow velocity of the medium, in particular the fluid, is also taken into account when controlling the compensation element. For this purpose, appropriate measuring devices or sensors, for example Pitot tubes, can be provided in the fluid line at a suitable location.

[0080] Alternatively or additionally to this feedback control, a further embodiment of the invention can integrate a "feedforward" method or disturbance feedforward into the control system to further increase its effectiveness. For this purpose, the pressure fluctuation is also measured downstream, i.e., in the fluid line connected to the outlet of the hollow body, and fed into the control loop after appropriate filtering.

[0081] The invention provides for using the pressure force acting on the actuator as the primary control variable. The aim of this control strategy is to control the actuator in such a way that changes in the pressure force are minimized or compensated for. Accordingly, the force acting on the actuator is kept as constant as possible. Furthermore, according to the invention, a force sensor or force transducer can be provided on the actuator, which can be arranged between the actuator and the compensation volume, and which detects a change in the pressure force resulting from a change in the compensation volume.

[0082] In this embodiment of the invention, an actuator, for example a piezo actuator, can be combined with a piezo-based force sensor.

[0083] The advantage of a piezoelectric force sensor is that it cannot measure constant DC pressure and only detects changes in force. In such a piezoelectric ceramic element, the application of force creates a charge distribution that is proportional to the force and can be measured. Piezoelectric force sensors can be used to measure both pressure and shear forces. A further advantage of using piezoelectric force transducers is their ability to measure highly dynamic forces.

[0084] The advantage of this control strategy is that no pressure sensor is required in or on the fluid line. These sensors can be very sensitive, potentially requiring complex monitoring of their functionality during operation.

[0085] In one embodiment of the invention, a special pressure sensor is provided for measuring the total pressure. This makes it 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 high pressures, for example at a pressure of 50 kPa or more, preferably 100 kPa or more.

[0086] The pressure sensor according to the invention is designed to detect relative pressure. In such a pressure sensor, the pressure difference on two sides of the sensor element is evaluated. With the same mean pressure on both sides, fluctuations in the mPa range can be measured. One input of the pressure sensor can be directly connected to the fluid line. This ensures that all pressure fluctuations on this side can be detected. However, a high overall pressure also prevails on this side. From a suitably chosen distance downstream in the fluid line, the pressure feedback can be applied to the other input of the pressure sensor. By using a capillary tube of the correct length and diameter and utilizing the volume at the pressure sensor, it can be ensured that pressure fluctuations above a certain frequency cannot reach this side of the pressure sensor.In this way, a low-pass filter can be designed with a cutoff frequency determined by the geometry of the capillary channel and the volume of the pressure sensor. This design ensures that the pressure sensor does not measure the constant pressure, but only detects fluctuations above the cutoff frequency of the low-pass filter. This principle can be used for the feed-forward sensor by placing the capillary tube downstream of the pressure actuator. For the feedback sensor, both the main connection and the capillary tube are connected downstream of the pressure actuator.

[0087] In addition to the aforementioned embodiments of a compensation element for the active damping of vibrations of a medium, various other embodiments are possible and planned, particularly with regard to the actuator and the sensors, some of which will be presented below. Naturally, it is also possible and planned to combine these. It should also be understood that this list is not exhaustive.

[0088] In an advantageous embodiment of the invention, the compensation element can comprise three active elements: an optional pressure sensor at the input of the compensation element to measure the disturbance entering the compensation element, on the upstream side, an actuator designed to change the size of the compensation volume in such a way as to influence the pressure fluctuation in the medium, and an optional pressure sensor at the output of the compensation element, downstream, which can be used as a feedback sensor.

[0089] In most embodiments, at least one pressure sensor is provided, or two pressure sensors are used as described above, which can improve performance. These three elements can be combined into a single unit or used as three separate elements that can be connected with (short) lines, hoses, or pipe sections as needed.

[0090] Changing 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, or by deforming a closed compensation volume containing the fluid. A flexible hose or tube, which can be deformed in a controlled manner, or a type of bellows element that is compressed or stretched to bring about the desired volume change, can also be used as the compensation volume. In a further embodiment of the invention, a compensation element for actively damping vibrations of a medium, particularly a fluid, is provided, wherein a hollow body with an internal volume is already supplied by the fluid line.

[0091] The internal volume of the fluid line thus provides the compensation volume, which can be increased or decreased by an actuator during operation. The actuator can be located outside the internal volume. The fluid line can be curved, at least in sections. The actuator can be positioned between two opposing curved sections of the fluid line and rigidly connected to the outer surface of these sections. During operation, the actuator can exert a tensile or compressive movement on the two sections of the fluid line, causing them to be pulled together or pushed apart.

[0092] In this way, the internal volume provided by the fluid line can be varied in size. It is understood that the fluid line can be designed to be sufficiently elastic to support the movement of the actuator.

[0093] For this purpose, the fluid line can, for example, be made of an elastic plastic.

[0094] However, in applications under vacuum or deep vacuum, in lithography or electron beam applications, and / or with aggressive or corrosive media, plastics can be problematic and therefore cannot be used. For this reason, metallic materials, such as stainless steels or high-grade steels, are also considered, or alternatively or additionally, coatings, such as PVD coatings.

[0095] The curvature can also be designed as a full circle or as a complete turn of the fluid line. The effect can be further increased if more than one turn is provided, for example two, three, or four turns.

[0096] In a further development of this embodiment of the invention, a compensation element for the active damping of vibrations of a medium, in particular a fluid, is provided, wherein a hollow body with an internal volume is also provided by the fluid line. The internal volume of the fluid line thus provides the compensation volume, which can be increased or decreased during operation by an actuator. The actuator can be arranged outside the internal volume.

[0097] In this embodiment, the fluid line can be straight. The fluid line can be fixed via at least two spaced-apart bearing points, with the actuator preferably positioned centrally between these two bearing points. The actuator is connected to the outside of the fluid line, preferably approximately centrally between and opposite the two bearing points.

[0098] If the actuator exerts a tensile or compressive force on the fluid line during operation, this can cause a radial movement of the fluid line between the two bearing points, which can cause a deflection of the fluid line in this section, by means of which the compensation volume can also be changed and adjusted to compensate for a pressure fluctuation.

[0099] In a further refinement, it is provided that the side of the fluid line opposite the actuator's point of attack is fixed. A pressure force exerted by the actuator can then move the wall of the fluid line on the side facing the actuator towards the opposite wall, thus also reducing the compensation volume. This embodiment requires a higher pressure force from the actuator compared to the previously described embodiment with only two bearing points.

[0100] It goes without saying that even with these designs, a certain degree of flexibility or elasticity of the fluid line must be ensured.

[0101] Accordingly, the present invention relates in a further aspect to a compensation element for the active damping of vibrations of a medium, in particular a fluid, wherein a hollow body with an internal volume is already provided by the fluid line itself. The required volume change for the active damping of vibrations can be effected by a substantially radial deflection of the fluid line as a whole or by deflection of only one wall of the fluid line by means of the actuator during operation.

[0102] In a further development, it is proposed that the fluid line be designed to be flexible in its longitudinal direction. For this purpose, it can, for example, incorporate a type of bellows, so that instead of radial deflection, an axial change in length of the fluid line is possible. The actuator can be arranged parallel to the axis and, through appropriate tensile or compressive forces, cause a longitudinal change in the fluid line in the area of ​​the bellows, which can also result in a change in volume.

[0103] Accordingly, the present invention relates in a further aspect to a compensation element for the active damping of vibrations of a medium, in particular a fluid, wherein a hollow body with an internal volume is already provided by the fluid line itself, and wherein the required volume change for the active damping of vibrations can be effected by longitudinal change of the fluid line.

[0104] A further aspect of the invention includes a method for actively damping vibrations of a medium, in particular a fluid, comprising the following steps: Providing a compensation element according to the invention, detecting the total pressure of a medium in a fluid line with a pressure sensor, determining the inlet pressure difference ΔP E to a predetermined pressure P, calculating a target value for an electrical parameter, in particular the electrical voltage, for an actuator and transmitting the target value to the actuator, changing the compensation volume by means of the actuator based on the target value to reduce or increase the compensation volume in such a way that the pressure difference can be compensated by changing the volume.

[0105] According to the invention, the method comprises a compensation element as described above.

[0106] In a further aspect of the invention, a system for actively damping vibrations or oscillations of a medium, in particular a fluid, is also included, which is configured to carry out a method for actively damping vibrations or oscillations of a medium, in particular a fluid, as described above. The system may include a compensation element as described above.

[0107] The system according to the invention can be used very advantageously for cooling machines, systems or other equipment, whereby these machines, systems or equipment are protected from pressure fluctuations and associated vibrations.

[0108] In general, the compensation element or the system according to the invention for actively damping vibrations or oscillations of a medium can also be used in various systems or processes where a mass flow is to be controlled as precisely and / or quickly as possible to a setpoint, and / or where a time-limited mass flow of a fluid is to be ensured, for example also for mixing fluids.

[0109] This could include, for example, various processes or systems in the chemical industry, the semiconductor industry, lithography, or electron beam devices, reactor chambers, etc.

[0110] The system can include a fluid line, at least partially filled with a medium, in particular with a fluid such as water or oil, whereby a specific total pressure of, for example, 1 Pa, 100 Pa, 1 kPa, 10 kPa or even 100 kPa can be set during operation.

[0111] The compensation element according to the invention ensures that a pressure fluctuation during operation can be maintained in this system, which can be + / - 10 mPa or less, preferably + / - 5 mPa or less, and particularly preferably + / - 5 mPa or less. This allows the invention to be used on or with fluid lines and associated machines, systems, or other equipment, for example in the semiconductor industry, which are highly sensitive to pressure and / or temperature fluctuations. In this way, for example, deformations in or on the machines can also be prevented.

[0112] Plants or other facilities, for example in the semiconductor industry, should be prevented.

[0113] For example, a water cooling circuit is envisioned to which semiconductor industry equipment or facilities are connected, and which are sensitive to pressure and / or temperature fluctuations in the water cooling circuit or have sensitive parts.

[0114] In one aspect, the invention also relates to a system for controlling a mass flow of a medium, in particular a fluid, comprising a compensation element according to the invention as explained above.

[0115] In another aspect of the invention, this system can be used for dosing fluids or for mixing fluids.

[0116] This mass flow rate can, for example, refer to a fluid circulating in a closed loop within a reactor chamber. A block flow or mass flow rate of any kind can be flexibly defined and more effectively implemented in this way, since the system's inertia is very low.

[0117] Further details of the invention will become apparent from the description of the illustrated embodiments and the attached claims.

[0118] The drawings show: Fig. 1 shows the basic structure of a compensation element for the active damping of vibrations of a medium in a sectional view; Fig. 2 shows the basic structure of a compensation element for the active damping of vibrations of a medium in a sectional view based on an embodiment in which the internal volume is divided into a compensation volume and a balancing volume; Fig. 3 shows the basic structure of a compensation element according to the invention for the active damping of vibrations of a medium in a sectional view based on an embodiment in which the internal volume is divided into a compensation volume and a balancing volume, in a further embodiment comprising a force sensor on the actuator; Fig. 4 shows an embodiment of a system for the active damping of vibrations of a medium with a compensation element; Fig. 5 shows the basic structure of a pressure sensor particularly suitable for the compensation element.Fig. 6 the basic structure of a further compensation element for the active damping of vibrations of a medium in a side view, wherein the hollow body is already provided by the fluid line, which is curved at least in sections, Fig. 7 the basic structure of yet another compensation element for the active damping of vibrations of a medium in a side view, wherein the hollow body is already provided by the fluid line, and wherein the fluid line comprises at least one straight section, Fig. 8 the basic structure of yet another compensation element for the active damping of vibrations of a medium in a side view, based on the embodiment from . Fig. 7, with a continuous bearing of the fluid line at least in the straight section, Fig. 9 the basic structure of a further compensation element for the active damping of vibrations of a medium in a side view, wherein the hollow body is already provided by the fluid line, and wherein the volume change takes place in the longitudinal direction of the fluid line, and Fig. 10 the response behavior of the control according to the invention in comparison. Detailed description of preferred embodiments

[0119] In the following detailed description of preferred embodiments, for the sake of clarity, the same reference numerals denote essentially identical parts in or on these embodiments. However, to better illustrate the invention, the preferred embodiments depicted in the figures are not always drawn to scale.

[0120] Fig. 1Figure 1 shows in an exemplary embodiment the basic structure of a compensation element 1 for the active damping of vibrations of a medium, in particular a fluid, in the representation by the curved line 24 only for illustration purposes, in a sectional view.

[0121] The compensation element 1 in the exemplary embodiment of the Fig. 1 is designed as a compensation element 10 with an actuator 30, which is arranged in an inner volume 23 of a hollow body 20.

[0122] The following figures show further preferred embodiments and configurations of compensation elements 1, which are designated by reference numerals 11, 12, 13, 14, 15 and 16.

[0123] The compensation element 1, 10, 11, 12, 13, 14, 15 and 16 comprises a hollow body 20 having an internal volume 23, wherein a compensation volume 41 is formed in the internal volume 23, wherein the hollow body 20 further has at least two openings 21, 22 which can connect the compensation volume 41 to the environment, and at least one actuator 30 which is arranged in the internal volume 23 and which can increase or decrease the compensation volume 41 during operation.

[0124] When designing the compensation element 1, 10, 11, 12, 13, 14, 15 and 16, care must be taken to avoid turbulent flows, which can also be caused by the compensation element itself, as far as possible.

[0125] The medium 24 can be in gaseous or liquid form and, in this case, comprises a liquid fluid with low compressibility, for example, oil or water. The medium 24 is contained in a piping system, a fluid line, a hydraulic line, a pressure line, or generally in any other suitable container or vessel.

[0126] Fluid lines 51, 52, 53 are purely examples for illustration in the Fig. 4 Figure 1 shows an embodiment of a system 100 for actively damping vibrations of a medium 24, in particular a fluid, using the compensation element 11. The fluid line 51 is the fluid line through which the medium 24 is supplied. The fluid line 51 can, for example, be connected to a pump 54, which is shown for illustrative purposes only. Fig. 4 is marked.

[0127] The arrangement is such that the pressure fluctuations to be compensated occur in the fluid line 51, which thus represents the supply line in the direction of flow. Reference numeral 52 denotes the embodiment of the Figure 1 , 2 , 3 and 4 the fluid line which is arranged downstream of and leads away from the compensation element 11 in the flow direction. Regarding system 100 of the Fig. 4 This will be discussed in more detail below.

[0128] In the Fig. 1 For clarity, the fluid line is not shown. During operation, the fluid line and the compensation volume 41 are filled with the viscous medium 24, in this example a liquid fluid. In the embodiments, the fluid line and the compensation volume 41 are completely filled with the fluid.

[0129] The medium 24 can include, in particular, low-salinity water, pure water, highly purified water, or especially "ultrapure water," as required and specified for the semiconductor industry. It is also possible to use the compensation element with fluorine-containing media, especially fluids, such as fluorine-containing liquids, particularly water.

[0130] In general, medium 24 can also include aggressive and / or corrosive fluids, i.e. liquids and gases.

[0131] The openings 21, 22 of the compensation element 10 are connected to the fluid lines 51, 52 by force-fit and / or positive locking during operation. Suitable connecting elements, e.g., couplings, screw connections, or other suitable fittings, are provided for this purpose to form a force-fit and / or positive locking connection between the fluid lines 51, 52 and the openings 21, 22.

[0132] In this embodiment, these connections can also be detached non-destructively, thus allowing for both easy installation and replacement of the compensation element. For active vibration damping, the compensation element is mechanically and fluid-tightly connected to the fluid lines 51, 52. In this context, "mechanically" means that the connection is sufficiently resistant to pull-out and vibration during operation, which is ensured by suitable dimensions and material selection of the joining partners, specific to the application.

[0133] The first opening 21 is used in operation as an inlet or inlet opening for supplying the medium 24 and the further opening 22 as an outlet or outlet opening for draining the medium 24, when the corresponding fluid lines 51, 52 are installed.

[0134] The opening 22 of the hollow body 20 thus provides the outlet for the medium 24 during operation, which can enter the internal volume 23 of the hollow body 20 via the inlet 21. Pressure fluctuations in the fluid line 51 supplying the fluid can be at least reduced or ideally completely compensated by the compensation element. In other words, pressure fluctuations on the inlet side are only reduced or ideally no longer transmitted to or into the fluid line 52 connected to the outlet 22.

[0135] An oscillation occurring at input 21 with an input amplitude is damped, so that the output amplitude at output 22 is lower than the input amplitude. The output amplitude at output 22 of the compensation element is therefore preferably no more than 50%, 40%, 30%, 10%, or even 1% or less, for example 0.5% or less, with respect to the input amplitude.

[0136] In the Fig. 1 Reference numeral 71 represents the incoming pressure P + ΔP E, and reference numeral 72 represents the outgoing pressure P, for illustrative purposes.

[0137] Pressure fluctuations or pressure surges can occur due to dynamic pressure changes and are transmitted through the medium 24 in the fluid line 51. Excessive pressure surges can cause damage to or within the affected systems 100, or to machines 50, equipment, or other facilities connected to the system 100, for example, in the semiconductor industry. Fittings, pumps 54, or even foundations directly connected to the fluid line 51, 52 can also be damaged by pressure surges.

[0138] 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 increased or decreased in order to compensate for or at least minimize pressure fluctuations occurring in the fluid line 51, 52. Longitudinal waves in the viscous medium 24 resulting from these pressure surges can be absorbed by the compensation volume 41.

[0139] The compensation volume 41 provides the volume that can be specifically and actively changed by the actuator 30 during operation in order to compensate for these pressure fluctuations in the fluid line 51, 52. The actuator 30 can reduce or increase the compensation volume 41 by means of a movement, for example, a lifting movement.

[0140] In the embodiment from Fig. 1The actuator 30 is arranged on the inner wall of the inner volume 23 of the hollow body 20. This allows for a particularly simple design. The geometry, and thus the volume occupied by the actuator 30, is selected such that the compensation volume 41 results from the remaining volume when the actuator 30 is in its rest position within the hollow body 20.

[0141] In this embodiment, 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.

[0142] For this purpose, the actuator is provided with a corrosion protection coating, for example, based on materials including tantalum, Inconel, molybdenum, or combinations thereof. PVD coatings are also possible. Certain high-purity plastics can also be suitable materials, including, for example, PVDF-HP, ECTFE, or ceramic materials such as SiC.

[0143] In this embodiment, it is particularly advantageous to dispense with additional internal components, such as those for protecting the actuator 30. In this way, the compensation element 10 can be kept very simple and compact. The geometry and material of the actuator 30 are selected such that, during operation, the movement of the piezoelectric material leads to the desired change in the compensation volume 41.

[0144] In general, the actuator 30 can also have other geometries or be made of other materials and be based on a magnetic, piezoelectric, or electrostatic principle. It is advantageous if the actuator 30 has a direct and rapid response time.

[0145] Applying a voltage causes deformation of the actuator 30, which leads to a change in the actuator's volume within the hollow body 20. An increase in the compensation volume 41 can absorb a positive pressure surge. A decrease in the compensation volume can absorb a negative pressure change or a vacuum.

[0146] At the in Fig. 1 In the embodiment shown, the movement of the actuator 30 and / or the distance of the actuator 30 to the input side, i.e. in the area of ​​the opening 21, is greater than on the output side, i.e. in the area of ​​the opening 22. This improves the damping properties.

[0147] In the exemplary embodiment, this is achieved by an inclined surface 31 of the body of the piezoelectric material. Due to the inclination, in which Fig. 1 Characterized by the angle α, the distance to the two openings 21, 22 varies. The angle α is at least 1°, preferably at least 5°, and particularly preferably at least 10°. In the illustrated embodiment, the angle α is approximately 5°.

[0148] In a further embodiment, it is provided that the internal volume 23 is divided into two partial volumes. Figures 2 and 3 show the basic structure of two compensation elements 11, 12 for the active damping of vibrations of a viscous medium 24 in a sectional view based on two embodiments in which the internal volume 23 is divided into a compensation volume 41 and a balancing volume 42, in a sectional view.

[0149] A flexible membrane 43 is provided, which separates the compensation volume 41, thereby creating an equalization volume 42 within the internal volume 23. The compensation volume 41 is in turn assigned to the space adjacent to the openings, so that it can receive the medium 24 from the fluid lines 51, 52. The compensation volume 41 is thus enclosed within the hollow body 20 by the flexible membrane 43, so that the medium 24 cannot escape.

[0150] The advantage of these embodiments is that, for example, the actuator 30 is protected outside the compensation volume 41 and is thus protected from direct contact with 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, in turn, be changed by a corresponding movement of the actuator 30.

[0151] The flexible membrane 43 can, for example, comprise a bellows or be designed as a bellows, as shown by the Figures 2 and 3 To indicate this, generally elastomers are considered as materials, provided they possess sufficient elasticity for the required deformations, for example, rubber, or metallic materials such as stainless steels or high-grade steels in a suitable design. When selecting the material, care must be taken to ensure that it can withstand the required pressure values ​​that will occur during operation.

[0152] During operation, the compensation volume 41 absorbs the medium 24, for example a fluid from the fluid line 51. In the Fig. 2 In the illustrated embodiment of the compensation element 11, a pressure body 44 is provided, which can be moved by the actuator 30 and thereby act on the flexible membrane 43. This improves or simplifies the force transmission from the actuator 30 to the flexible membrane 43.

[0153] 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 regulated by an electronic computer unit 95.

[0154] The computer unit uses stored programs or value tables to determine a target value for the actuator 30, which is then transmitted to it to control the compensation. For this purpose, the controller or another suitable control element can be used. The target value relates to at least one electrical parameter; in this embodiment, the voltage applied to the actuator 30. The movement of the actuator 30, or its extension, is controlled by the applied voltage. This, in turn, influences and adjusts the size of the compensation volume 41 accordingly.

[0155] According to a preferred embodiment, the actuator 30, and thus the size of the compensation volume 41, is controlled by the computer unit based on the deviation of the current pressure from a predetermined pressure at the inlet opening 21. Therefore, during operation, a total pressure is present at the inlet opening 21, which is composed of the predetermined pressure P and the pressure difference ΔP E.

[0156] The total inlet pressure is therefore PE = P + ΔP E. Alternatively or additionally, the total pressure can also be measured at one or more points in the fluid line 51 on the side that is exposed to the potential pressure fluctuations.

[0157] In the Fig. 4This is schematically represented by the two pressure sensors 61 and 62, one of which is assigned to the inlet 21 and the other to the fluid line 51. If the pressure sensor 62 of the fluid line 51 is positioned at a sufficient distance from the opening 21, a certain lead time can occur. This is because a pressure change occurring during operation is first detected downstream by pressure sensor 62 and, with a time delay, by pressure sensor 61. This allows the actuator 30 to be controlled proactively, so that the pressure difference can be compensated even more effectively. The actuator 30 is controlled in real time. In this way, a pressure difference can be balanced in real time.

[0158] The control system is advantageously designed with a high bandwidth, enabling it to respond to very slow changes, such as those below 0.01 Hz, as well as to high frequencies up to 10 kHz. This can be achieved both analogously and digitally. A fundamentally suitable control system is described in the applicant's document EP 1 840 681 A1, which is hereby fully incorporated into the present invention.

[0159] Using stored algorithms, the computer unit determines a target value for the electrical voltage that should be applied to the actuator 30, based on the data from the pressure sensors 61, 62.

[0160] Instead of fixed programmed algorithms for controlling or regulating the compensation element, a further development of the invention also envisages the use of "machine learning" methods or artificial neural networks for control purposes.

[0161] This can be helpful, for example, when several compensation elements with multiple actuators are to be jointly controlled and regulated, and / or when several compensation elements are connected to form a larger, complex network or system of fluid lines. Further training can then be used to consider additional data or parameters from other systems, machines, or installations connected to the network for the control strategy, such as room temperatures or temperatures on or in the systems or machines.

[0162] PID controllers can also be used for regulation.

[0163] In this way, the actuator control can be switched to a self-learning mode and, for example, recognize certain patterns in the pressure changes, enabling even faster and more precise compensation. For this purpose, pressure sensors can also be arranged at several points in the fluid line 51, 52, 53, for example upstream of pumps, valves or similar fittings, so that information about pressure changes can be acquired very early on.

[0164] In one embodiment, it is also provided that the flow velocity of the medium 41, in particular the fluid, is taken into account when controlling the compensation element.

[0165] The actuator 30 performs a movement adapted to the pressure deviation ΔP E, so that the pressure difference in the hollow body 20 is reduced or ideally completely compensated by adjusting the compensation volume 41. Thus, a pressure fluctuation occurring in the fluid line 51 can be minimized or ideally completely compensated, so that for the total pressure PA at the outlet opening 22: PA = ≈ P or ideally PA = P, and therefore ΔP E ≈ 0 Pa or ΔP E = 0 Pa.

[0166] In one embodiment, the control is achieved using the "feedback control" method, or as a feedback-based control system. The required movement of the actuator 30 is determined by suitable filters in a controller. During the design of the control system, nonlinear and / or hysteresis effects of the actuator 30, for example, of the piezoelectric material, are already taken into account in order to prevent overshoot, i.e., excessive damping.

[0167] Alternatively or additionally to this feedback control, a "feedforward" method or disturbance feedforward can also be integrated into the control system in a further embodiment to increase its effectiveness even further. For this purpose, the pressure fluctuation is also measured downstream, i.e., in this exemplary embodiment, in the fluid line 52, which is connected to the outlet opening 22 of the hollow body 20. In the Fig. 4 For illustrative purposes only, another pressure sensor 63 is shown.

[0168] While in these embodiments the pressure sensors are assigned to the components carrying the medium 24, i.e. the inputs 21, 22 or the fluid lines 51, 52, in Fig. 3 An embodiment of a compensation element 12 is shown, which is based on the embodiment of the Fig. 2based on, but additionally comprising a force sensor or force transducer 32 on the actuator 30 according to the invention, and which is therefore arranged between the actuator 30 and the compensation volume 41.

[0169] 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 pressure force acting on the actuator 30 is used as the primary control variable. The force difference ΔF is calculated as follows: ΔF = ΔP E * A, where A = size of the area of ​​application. The goal of the control in this case is to minimize or ideally completely compensate for the force difference acting on the actuator 30, so that ΔF ≈ 0 N or ΔF = 0 N.

[0170] The change in the compensation volume 41 during operation depends on the pressure force acting on the actuator 30. The advantage of this method is that no pressure sensor is required in or on the fluid line 51, 52.

[0171] In one embodiment, a special pressure sensor 70 is provided for measuring the total pressure, which can be used particularly well together with the compensation element. This sensor is shown schematically in a basic structure in the figure below. Fig. 5 shown.

[0172] The pressure sensor 70 detects a relative pressure in the fluid line 51, whereby the pressure difference on two sides of the sensor element is evaluated. With the same mean pressure on both sides, fluctuations in the mPa range can be measured.

[0173] One input of the pressure sensor 70 is directly connected to the fluid line 51 via a supply line 73. This ensures that all pressure fluctuations on this side are detected. From a certain distance downstream in the fluid line 51, pressure is fed back to the second input of the pressure sensor 70. By using a capillary tube 74 of the correct length and diameter, and utilizing the volume of the pressure sensor 70, it is ensured that pressure fluctuations above a certain frequency cannot reach this side of the pressure sensor. In this way, a low-pass filter is formed with a cutoff frequency determined by the geometry of the capillary tube 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 fluctuations above the cutoff frequency of the low-pass filter.This principle can be used for the feed-forward process.

[0174] 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 high pressure, for example at a pressure of 50 kPa or more, preferably 100 kPa or more.

[0175] Other suitable pressure measurement methods may include laser interferometers to measure pressure differences radially and / or axially in a fluid line, or acceleration sensors.

[0176] Measuring methods or sensors that enable the measurement of the pressure difference are particularly suitable for the invention.

[0177] Fig. 6Figure 1 shows the basic structure of a further compensation element 13 for the active damping of vibrations of a medium 24 in a side view, wherein the hollow body is already provided by the fluid line 51. This is curved, at least in sections.

[0178] The internal volume 23 of the fluid line 51, 52 thus provides the compensation volume 41, which can be increased or decreased by the actuator 30 during operation. In this embodiment, the actuator 30 is arranged outside the internal volume 23. The fluid line 51 is curved or designed with a bend, at least in sections.

[0179] The actuator 30 is arranged between two opposing curved sections 56 of the fluid line 51 and is rigidly connected to these sections 56. During operation, the actuator 30 can exert a tensile or compressive movement on the two sections 56 of the fluid line 51, so that these sections 56 can be pulled together or pushed apart. Additional force transmission elements 34, such as rods or tubes, can be provided for this purpose.

[0180] In this way, the internal volume 23 provided by the fluid line 51, 52 can be changed in size. It is understood that the fluid line 51 is designed to be correspondingly elastic and can, for example, be made of an elastic plastic. In the exemplary embodiment, a hose is provided.

[0181] The curvature can be designed as a full circle or as a complete turn of the fluid line 51, as shown in the exemplary embodiment. The effect can be further increased if more than one turn is provided, for example two, three or four turns.

[0182] Fig. 7 Figure 1 shows the basic structure of a further compensation element 14 for the active damping of vibrations of a medium 24 in a side view, wherein the hollow body is also already provided by the fluid line 51. Instead of a curved section, the fluid line 51 comprises at least one straight section according to this embodiment.

[0183] The actuator 30 is also arranged outside the inner volume 23. The fluid line 51 is fixed via two spaced-apart bearing points 57, with the actuator 30's point of force application located approximately midway between these two bearing points 57. The actuator 30 is rigidly connected to the outside of the fluid line 51.

[0184] When the actuator exerts a tensile or compressive force on the fluid line 51 during operation, this can cause a radial movement of the fluid line 51 between the two bearing points 57, resulting in a deflection of the fluid line 51 in this section. In this way, the compensation volume 41 can be changed and adjusted to compensate for pressure fluctuations. Reference numeral 58 illustrates a possible deflection of the fluid line 51 when a compressive force is applied by the actuator 30.

[0185] Fig. 8shows the basic structure of a further compensation element 15 for the active damping of vibrations of a medium 24 in a side view, based on the embodiment from Fig. 7 . Unlike the embodiment of the Fig. 7 The side of the fluid line 51 opposite the attack side of the actuator 30 is fixed. In the exemplary embodiment, several bearing points 57 are provided for this purpose.

[0186] A pressure force applied by the actuator 30 can move the wall of the fluid line 51 on the side facing the actuator 30 towards the opposite wall of the fluid line 51, so that the compensation volume 41 can also be reduced. In this embodiment, a higher pressure force from the actuator 30 is required compared to the one described above with only two bearing points 57. Reference numeral 59 illustrates a possible deflection of the fluid line 51 when a pressure force is applied by the actuator 30.

[0187] In these embodiments of the compensation element 13, 14 and 15, a certain flexibility or elasticity of the fluid line 51 must be ensured.

[0188] Fig. 9 shows the basic structure of a further compensation element 16 for actively damping vibrations of a medium 24 in a side view, wherein the hollow body is already provided by the fluid line 51, and wherein the volume change occurs in the longitudinal direction of the fluid line 51. In this embodiment, the fluid line 51 is designed to be flexible in its longitudinal direction. For this purpose, a bellows 60 is provided, so that an axial change in length of the fluid line 51 is possible. The actuator 30 is arranged parallel to the axis and can, by corresponding tensile or compressive forces, effect a longitudinal change in the fluid line 51 in the area of ​​the bellows 60, which can also cause a change in the volume of the compensation volume 41.

[0189] The fluid line can generally be made of plastic and may also include elastomers, for example.

[0190] For applications requiring contact with aggressive or corrosive fluids, such as ultrapure water, and / or operating in a vacuum or deep vacuum, special materials and / or coatings or protective layers that are resistant to the fluids are suitable.

[0191] In the case of aggressive or corrosive fluids, such as low-salt, pure, or especially ultrapure water, suitable corrosion protection coatings are considered, for example, those based on or comprising tantalum, Inconel, molybdenum, or combinations thereof. PVD coatings are also conceivable. Metallic materials, including stainless steels, can also be suitable for the fluid line.

[0192] Certain plastics, which are suitable for vacuum applications, for example, can also be suitable materials, including PVDF-HP, ECTFE, or ceramic materials such as SiC.

[0193] A further aspect of the invention includes a method for actively damping vibrations of a medium 24, in particular a fluid, comprising the following steps: Providing a compensation element 1, 10, 11, 12, 13, 14, 15, 16 according to the invention, detecting the total pressure of a medium 24 in a fluid line 51, 52, 53 with a pressure sensor 61, 62, 63, 70, determining the inlet pressure difference ΔP E to a predetermined pressure P, calculating a target value for an electrical parameter, in particular the electrical voltage, for an actuator 30 and transmitting the target value to the actuator 30, changing the compensation volume 41 by means of the actuator 30 based on the target value to reduce or increase the compensation volume 41 such that the pressure difference can be compensated by changing the volume.

[0194] In a further aspect of the invention, a system 100 for actively damping vibrations of a viscous medium 24, in particular a fluid, is also included, which is configured to carry out a method for actively damping vibrations of a medium 24, in particular a fluid, as described above.

[0195] System 100 includes one compensation element 1. Fig. 4 Figure 1 shows an embodiment of such a system 100 for actively damping vibrations of a viscous medium, using only one compensation element 11 as an example, wherein other compensation elements 10, 12, 13, 14, 15, 16 can also be used instead of the compensation element 11.

[0196] System 100 comprises a fluid line 51, 52 as a supply line for a purely exemplary machine 50, system, or device, which is completely filled with a medium 24, in this 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 set in System 100.

[0197] In the Fig. 4 Furthermore, a fluid line 53 is shown, which leads away from the machine 50. The direction of flow is indicated by the reference symbol 55.

[0198] The compensation element makes it possible to ensure that in this system 100 a pressure fluctuation during operation can be ensured which can be + / - 10 mPa or less, preferably + / - 5 mPa or less, particularly preferably + / - 5 mPa or less.

[0199] For the in Fig. 4The illustrated embodiment of a system 100 for actively damping vibrations of a medium with a compensation element provides a nominal flow rate of 2 L / min, using a hose with an 8 mm inner diameter. The nominal pressure is 1.3 bar. The compensation volume is provided by a stroke area 33 of 25 mm², which can be moved by ± 5 µm by means of the actuator 30. This allows, for example, the compensation of a pressure disturbance in a range of approximately 50 to 150 Pa, for example 100 Pa, at 3 Hz.

[0200] At a frequency of, for example, 30 Hz, pressure surges of approximately 1000 Pa can be compensated for with a similar stroke. This is sufficient to reduce pressure fluctuations in many demanding applications. It goes without saying that the stroke area and / or the stroke length can be adjusted accordingly to enable the compensation element 1 to operate under different operating parameters and to adapt it to the available installation space or the chosen drive technology.

[0201] This makes the invention possible to be used on or with machines, systems or other equipment, for example in the semiconductor industry, which are highly sensitive to pressure fluctuations and which, for example, need to be cooled.

[0202] Fig. 10 demonstrates the response behavior of the control system according to the invention in a comparison using a simple example.

[0203] Reference numeral 91 represents a desired pressure change over time t.

[0204] Reference number 92 indicates the response behavior of a classic mass flow controller (MFC). Over time, relatively significant deviations from the setpoint for pressure p are shown, although a mass flow rate q can also be assumed.

[0205] Finally, reference number 93 indicates the response behavior that can be achieved with the compensation element 1, 10, 11, 12, 13, 14, 15, 16.

[0206] This demonstrates a higher level of dynamism in the control system, meaning a faster achievement of the target value, as well as a smaller deviation from the target value over time.

[0207] A desired mass flow rate of a fluid can thus be set very quickly and precisely, and time-delayed overshoot is significantly reduced.

Claims

1. A compensation element (1) for actively damping vibrations of a medium (24), in particular a fluid, comprising: - 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 connect the compensation volume (41) to the environment; and - at least one actuator (30) which can increase or decrease the compensation volume (41) during operation; characterised in that a force sensor (32) is provided on said actuator (30), which is arranged between the actuator and the compensation volume (41) and which captures a change in the pressure force acting on the actuator (30) as a result of a change in the compensation volume (41).

2. The compensation element (1) according to any one of the preceding claims, characterised in that the compensation element (1) comprises a fluid conduit (51, 52), a piping system, a hydraulic line, a pressure line, or any suitable container or vessel adapted to accommodate the medium, in particular the fluid.

3. The compensation element (1) according to the preceding claim 2, characterised in that the openings (21, 22) of the compensation element (1) are connected to the fluid conduit (51, 52) in a force-fitting and / or form-fitting manner, wherein the viscous medium (24) can pass or flow from the fluid conduit (51, 52) into the compensation volume (41) during operation.

4. The compensation element (1) according to any one of the preceding claims 2 and 3, characterised in that the first opening (21) of the hollow body (20) is connected to at least a portion (56) of the fluid conduit (51, 52), which is exposed to the pressure fluctuation, and / or that the second opening (22) of the hollow body (20) is connected to the fluid conduit (51, 52).

5. The compensation element (1) according to any one of the preceding claims, characterised in that, during operation, the actuator (30) is able to change the size of the compensation volume (41) by a movement, preferably by a stroke movement, preferably as a function of pressure fluctuations in the fluid conduit (51, 52).

6. The compensation element (1) according to any one of the preceding claims, characterised in that the internal volume (23) is divided into two partial volumes by a diaphragm (43), thereby defining an additional balancing volume (42) besides the compensation volume (41).

7. The compensation element (1) according to any one of the preceding claims, characterised in that a pressure body (44) is provided, which can be moved by the actuator (30) and can thereby act on the flexible diaphragm (43).

8. The compensation element (1) according to any one of the preceding claims, characterised in that at least one pressure sensor (61, 62, 63, 70) is provided for determining the total pressure, preferably inside at least one opening (21, 22) of the hollow body (20), and / or inside the fluid conduit (51, 52).

9. The compensation element (1) according to claim 2 and preferably according to a further one of the preceding claims, characterised in that the hollow body (20) having an internal volume (23) is provided by the fluid conduit (51, 52).

10. The compensation element (1) according to the preceding claim, characterised in that the change in volume is caused by the actuator (30) through a substantially radial deflection of the fluid conduit (51, 52) as a whole or by deflection of only one wall of the fluid conduit (51, 52) during operation.

11. The compensation element (1) according to the preceding claim 10, characterised in that the fluid conduit (51, 52) 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 (51, 52) .

12. A method for actively damping vibrations of a medium (24), in particular a fluid, comprising the steps of: - providing a compensation element (1) according to any one of the preceding claims 1 to 11; - capturing the total pressure of a medium (24) in a fluid conduit (51, 52) using a pressure sensor (61, 62, 63, 70); - determining the inlet side pressure difference ΔPin relative to a predefined pressure P; - 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); - 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.

13. A system (100) for actively damping vibrations of a viscous medium (24), in particular a fluid, configured for performing a method according to the preceding claim and / or comprising a compensation element (1) according to any one of claims 1 to 11.

14. A system (100) for controlling a mass flow rate of a medium (24), in particular a fluid, comprising a compensation element (1) according to any one of claims 1 to 11.

15. A machine (50), installation or other equipment, in particular in the semiconductor industry sector, comprising a compensation element (1) according to any one of claims 1 to 11.