Measuring drive, measuring device, method and use of a shaft comprising an ultrasonic bearing

Abstract

A measuring drive (100) for a measuring instrument (101), in particular a rheometer, is described. The measuring drive (100) comprises: 1) a motor (110); 2) a shaft (120) coupled to the motor (110) such that the shaft (120) can be driven by the motor (110); and 3) an ultrasonic device (130) configured to provide ultrasonic waves (135) to the shaft (120) such that at least a portion of the shaft (120) can be supported substantially contactlessly by means of the ultrasonic waves (135). Furthermore, a measuring instrument (101), a method, and a use are described.

Description

Technical Field

[0001] The present disclosure relates to a measuring drive for a measuring instrument, in particular a rheometer. Furthermore, the present disclosure relates to a measuring instrument for determining sample properties, in particular rheological and / or dynamic mechanical properties. Furthermore, the present disclosure relates to a method and a use thereof. Background Art

[0002] In principle, the method of measuring instruments (particularly rheometers) for determining the rheological properties of a sample is known and is described, for example, in documents AT 404 192 B or AT 515 219 B1. In short, a sample (mostly a liquid) is provided and held between two measuring components, at least one of which is connected to a shaft. The shaft is rotated by a measuring motor, with the rheological properties of the sample influencing the shaft's rotational motion, particularly the effective torque and normal force. The effective torque is typically determined by the motor current of the measuring motor or a mechanical spring. The resulting normal force can be measured in various ways (e.g., capacitively, optically), allowing conclusions to be drawn about the sample's rheological properties. For dynamic mechanical testing, the rotation of the measuring motor is optionally combined with the translational motion of another measuring mechanism. The shaft can have a circular disc (oriented perpendicular to the shaft's axial direction), which can further improve measurement accuracy. In this case, at least a portion of the circular disc, or the shaft, is arranged in an air gap and supported frictionlessly by additionally introduced compressed air (air bearing) or magnetic bearings. Furthermore, the friction-induced support can be realized by means of ball bearings or pivot bearings.

[0003] However, this application presents numerous drawbacks, particularly when measurements are performed under specialized conditions (e.g., high pressure). Air bearings are not feasible within closed pressure chambers, as the chambers are subject to pressure fluctuations that cannot be adequately corrected using conventional equipment during the compressed air supply process. Similarly, they are unsuitable in ultra-cleanrooms, in mobile environments, and particularly where compressed air could cause static electricity problems. For example, the use of compressed air on drilling platforms is prohibited due to the potential for ignition sparks caused by static electricity.

[0004] Using conventional rheometers in inert environments (e.g., argon glove boxes) is also highly disadvantageous. At flow rates of 200 L / min, conventional air bearings can only be introduced into ultra-clean rooms or inert environments at considerable expense. High flow rates in such enclosed spaces can lead to numerous technical challenges. Furthermore, the high flow rates of air bearings present numerous disadvantages in contaminated measurement areas (e.g., radioactive environments, toxic substances, highly reactive gases, etc.). Summary of the Invention

[0005] The object of the present disclosure is to provide a measuring drive for a measuring instrument, in particular a rheometer, which enables robust and efficient measurements even under special measuring conditions (e.g. pressure chambers, ultra-clean rooms, inert environments, compressed air decoupling areas).

[0006] This object is achieved by the subject matter having the features according to the independent claim. Further embodiments are indicated in the dependent claims.

[0007] According to one aspect of the present disclosure, a measuring drive for a measuring instrument, in particular a rheometer, is described. The measuring drive comprises: 1) (at least one) motor (in particular a measuring motor); 2) (at least one) shaft coupled to the motor so that the shaft can be driven by the motor; and 3) an ultrasonic device configured to supply ultrasonic waves to the shaft so that the shaft (or at least a portion of the shaft) can be supported (substantially) contactlessly by means of the ultrasonic waves.

[0008] According to another aspect of the present disclosure, a measuring instrument (particularly a rheometer) for determining information indicative of rheological properties of a sample (particularly a viscoelastic sample, more particularly a liquid) is described. The measuring instrument includes: 1) a measuring drive as described above; and 2) a sample carrier for positioning the sample, wherein a shaft is couplable to the positioned sample.

[0009] According to another aspect of the present disclosure, the use of the measuring instrument described above in a special measurement environment is described, such as a clean room (or ultra-clean room), a pressure chamber, an inert environment or a compressed air decoupling chamber.

[0010] According to another aspect of the present disclosure, a method is described for determining information indicative of rheological properties of a sample (particularly a viscoelastic sample, more particularly a liquid) by means of a measuring instrument (particularly a rheometer). The method comprises: 1) providing a sample and coupling the sample to a shaft; 2) driving the shaft (e.g., rotating it) by means of a motor (particularly a measuring motor) such that indicative information is reflected in the kinematic properties of the shaft (e.g., torque and / or normal force); 3) emitting ultrasonic waves to the shaft by means of an ultrasonic device such that at least a portion of the shaft is supported substantially contactlessly by means of the ultrasonic waves; and 4) acquiring the kinematic properties of the shaft (e.g., by measuring the current consumption of the motor, by measuring the normal force with capacitance, by measuring the axial deflection of a linear motor) to determine information indicative of the rheological properties of the sample.

[0011] According to a further aspect of the disclosure, the use of an ultrasound source for the (substantially) contactless support of (at least a portion of) a shaft in a measuring instrument, in particular a rheometer, is described.

[0012] In this document, the term "measuring drive" may specifically refer to a device that can be incorporated into a measuring instrument and provides the physical or mechanical motion necessary for measurements in the measuring instrument. These motions can be rotational, and / or rotationally oscillating, and / or translationally oscillating, and / or combinations of these. By combining two measuring motors, any desired motion combination can be predefined, wherein a sample between two measuring components is mechanically loaded and measured. According to one embodiment, the measuring drive may include a (measuring) motor, particularly a rotary motor or a linear motor, which provides rotational or linear motion. To this end, the motor may, for example, be coupled to a shaft, wherein the term "shaft" may specifically refer to a component whose extension in one spatial direction is significantly longer than in the other two spatial directions. Thus, the shaft may, for example, be designed as a (rotatable) rod. However, the shaft may also, for example, be designed as a tube or a rectangular rod. In one embodiment, the shaft is coupled to the motor (e.g., mechanically or magnetically) within the measuring drive and may be directly or indirectly coupled to the sample within the measuring instrument. Furthermore, the measuring drive can have a device for supporting the shaft. According to a particularly preferred embodiment, the device is an ultrasonic device that can provide ultrasonic waves so that the shaft can be supported in a contactless manner.

[0013] In this context, the term "measuring instrument" may particularly denote a device that is configured to measure physical properties of a sample and, for this purpose, uses a measuring drive comprising a motor-driven shaft. The measuring instrument can thereby measure information indicative of a physical / chemical property of the sample by means of a shaft that is directly or indirectly coupled to the sample. The indirect coupling of the sample to the shaft takes place via a measuring element on the shaft, with various measuring element systems being known, such as plate-plate arrangements, cone-plate arrangements, and concentric cylinder arrangements, as well as solid-phase fixtures for, for example, strain tests. Thus, a measuring instrument can, for example, be a "rheometer," which in turn is configured to determine the rheological properties of a sample. The term "rheometer" encompasses, for example, rotational viscometers, rotational rheometers, oscillation rheometers, or combined rotational-oscillation rheometers, as well as arrangements for dynamic mechanical analysis by linear loading.

[0014] In this article, the term "rheological properties" can particularly denote properties of a sample (in particular a liquid), which relate to deformation phenomena and / or flow phenomena of the sample. Here, the rheological properties can be, for example, the viscosity, elasticity or viscoelasticity of the sample. In this article, the term "indicative information" can particularly denote a measured variable that can be obtained by means of a measuring unit. For example, as described above, the rheological properties of a sample (coupled to a rotating shaft) can affect the motion characteristics of the rotating shaft. Thus, for example, the effective torque or the normal force can change corresponding to the viscoelastic properties of the sample. This change in the motion characteristic curve then corresponds to the indicative information, which can be obtained by the measuring unit (for example, by means of a motor current, an angle of rotation occurring or as a capacitance). Then, based on the indicative information, conclusions about the rheological properties of the sample can be drawn.

[0015] In this context, the term "substantially contactless" can specifically mean that there is no physical contact between at least a portion of the supported shaft (e.g., a shaft segment or shaft element) and the surrounding measuring drive and / or surrounding measuring instrument. In other words, in the contactless supported state, at least a portion of the shaft is not in physical / mechanical contact with another solid body. Instead, the shaft is levitated by the ultrasonic waves emitted by the ultrasonic device. Thus, in principle, at least a portion of the shaft "floats" without contact or friction.

[0016] In this document, the term "ultrasonic device" may particularly denote any device that can generate ultrasonic waves (sound pressure) that enable essentially contactless support of at least a portion of a shaft. The ultrasonic device may include one or more spatially separated ultrasound sources. The ultrasound sources may, for example, be positioned opposite each other on either side of the shaft. The ultrasound source may be a single device configured to provide the described ultrasonic waves. In addition to an ultrasound emitter, such a device may also include, for example, so-called sonotrodes and / or horns.

[0017] The term "ultrasonic" can particularly refer to high-frequency mechanical vibrations, wherein the frequencies outside the audible sound spectrum are essentially in the range of 15 to 100 kHz. Ultrasonic devices can be configured to operate components such as shafts in a contactless manner using ultrasound or ultrasonic levitation. In principle, two possibilities are known for this purpose: the standing wave effect in the ultrasonic field and the near-field effect in the ultrasonic field (see below). In this regard, in principle, the term "ultrasonic" can refer to ultrasonic vibrations or ultrasonic sound pressure, which are generated / provided to enable the levitation of an object, in particular the levitation of at least a portion of a measuring shaft. To generate ultrasonic waves in air, an ultrasonic emitter / generator can be used. This can be, for example, dynamic and electrostatic loudspeakers, and in particular piezoelectric loudspeakers. In this regard, a piezoelectric loudspeaker can be, for example, a plate coupled to a diaphragm made of piezoelectric ceramic, wherein the plate is excited to vibrate by the inverse piezoelectric effect.

[0018] According to one exemplary embodiment, the present disclosure is based on the concept of providing a measuring drive for a measuring instrument, particularly a rheometer, wherein, by providing contactless support of (at least a portion of) the shaft by ultrasonic means, robust and efficient measurements can be achieved even in extremely specialized measuring environments, such as pressure chambers, ultra-clean rooms, inert environments, or compressed air decoupling zones. Previously, the measuring instrument shaft was supported by compressed air, which, however, made many specialized measuring conditions impossible or at least significantly more difficult. Surprisingly, it has now been discovered that a particularly advantageous measuring drive for a measuring instrument is possible by using ultrasonic levitation. While the physical phenomenon of ultrasonic levitation is known in principle and is used for handling very small / lightweight specialized components such as thin films or wafers, it was previously unknown that contactless handling of the measuring shaft (rather than the sample) in a measuring instrument would prove particularly advantageous for extremely specialized measuring environments such as pressure chambers or ultra-clean rooms. However, this has been technically challenging and only achievable at great expense.

[0019] Unlike the previous use of compressed air to support the shaft in rheometers, the use of ultrasonic devices is significantly more convenient. No air flow (compressed air) and no gas processing is required. This results in lower costs and less energy consumption. Since it is not dependent on compressed air, the measuring instrument can be mobile, independent and flexible. In this way, it can even be used in completely closed environments (such as pressure chambers or pressure cavities). In addition, porous materials are no longer required, and (also due to the higher air gap) the design can be simpler and more robust. Instead of compressed air, other gases that still increase the load can be introduced into the air gap (such as argon). However, compared with other traditional bearing options, such as ball bearings, ultrasonic devices in measuring drives also offer clear advantages. As a result, residual friction can be significantly lower and compensability can be improved (for example, through a residual friction curve with a constant angle).

[0020] Furthermore, the described measuring drive can be integrated into existing systems in a simple and flexible manner. Furthermore, for example, indicator information (measured variables) can be determined via capacitive normal force measurement, and existing drive devices (e.g., motors and shafts) can be combined with the described measuring drive.

[0021] Additionally, additional exemplary embodiments of apparatus and methods are described.

[0022] According to one embodiment, the ultrasonic device is configured to emit ultrasound waves so that at least a portion of the shaft can be supported in a suspended (in particular frictionless) manner using the ultrasound waves. This can have the advantage of enabling robust and simultaneously frictionless support of the shaft. In this context, suspension can be understood as floating achieved by ultrasound without physical contact with other solid bodies.

[0023] According to another embodiment, the ultrasound device has at least two ultrasound sources, which are arranged (substantially) opposite each other, wherein the axis is arranged between the (substantially) opposite ultrasound sources. This can have the following advantages, namely, the ultrasound device can be designed flexibly and a variety of advantageous structures can be achieved.

[0024] A particularly stable, balanced and essentially deflection-free support can be achieved if ultrasound from two (or more, for example four) mutually opposing ultrasound sources is emitted onto the shaft.

[0025] According to another embodiment, the shaft comprises a shaft element, which is coupled to the shaft with its main extension direction (substantially) perpendicular to the axial direction of the shaft, wherein the ultrasound device is configured such that the shaft element can be supported (substantially) contactlessly by means of ultrasound. This offers the advantage that the measurement accuracy is increased by the shaft element and that the shaft element can be supported particularly efficiently for a variety of special applications.

[0026] A shaft element can be used to facilitate the measurement of indication information, or to more accurately determine the indication information. For example, the deflection of an ultrasonically supported shaft element can be measured (e.g., capacitively or optically). The shaft element has a main extension direction that is at least longer than another extension direction of the shaft element. If the shaft element is designed as a disk, for example, there are two main extension directions, both arranged perpendicular to the axial direction of the shaft. The shaft element is coupled to the shaft, for example, it is fixed thereto.

[0027] According to another embodiment, the ultrasonic device is configured to support the shaft element substantially contactlessly, both in the axial direction and in the radial direction. This has the advantage that both normal forces and transverse forces, as well as tilting moments, can be applied. This results in greater stability of the shaft element and more efficient measurement.

[0028] According to another embodiment, the ultrasound device has at least four ultrasound sources, wherein, viewed in the axial direction of the shaft, two ultrasound sources are arranged above the shaft element and two ultrasound sources are arranged below it, and wherein, viewed in the radial direction of the shaft, two ultrasound sources are arranged substantially opposite the other two ultrasound sources, with the shaft located therebetween. This offers the advantage that the support described above (of the shaft element) can be achieved in a simple manner in both the axial and radial directions.

[0029] According to another embodiment, the shaft comprises at least two shaft elements that are spatially separated from one another and thereby form a gap. The ultrasound device comprises at least two ultrasound sources that are arranged (substantially) opposite one another so that the emitted ultrasound is at least partially directed toward the gap, thereby enabling (substantially) contactless support of the at least two shaft elements. This can have the advantage of providing particularly efficient and stable support.

[0030] According to another embodiment, at least one shaft element (or both shaft elements) essentially has a shape selected from the group consisting of a circular disk, an annular disk, a plate, a truncated cone, a hemisphere, or a truncated pyramid. This can have the advantage of enabling a flexible design for specific applications. This list is illustrative and not exhaustive. Other advantageous designs of the shaft elements are also contemplated.

[0031] According to another embodiment, the ultrasound source comprises an ultrasound emitter and a sonotrode, wherein the sonotrode is arranged upstream of the emitter in the direction of sound emission. This can have the advantage that a particularly efficient ultrasound source with specifically adjustable properties can be used.

[0032] In this context, any device designed to generate ultrasound of a specific frequency can be referred to as an ultrasonic emitter (or ultrasonic generator). A device that is brought into resonance by the introduction of ultrasound is referred to as a sonotrode. The sonotrode can establish a connection between the ultrasonic emitter and the workpiece and adapt the ultrasonic vibrations to the machining task.

[0033] According to another embodiment, the ultrasound source further comprises a horn which is arranged between the emitter and the sonotrode. This can also have the advantage that a particularly efficient ultrasound source with specifically adjustable properties can be used.

[0034] In this regard, a specifically shaped ultrasonic oscillator or an additional component positioned between the ultrasonic emitter and the ultrasonic oscillator may be referred to as a horn. Positioned between the ultrasonic emitter and the ultrasonic oscillator, the horn can amplify the ultrasonic emitter's amplitude. The material and geometry of the horn, as a mechanical component, can be selected so that it has the emitter's frequency, or a multiple thereof, as its natural frequency. The material preferably has a suitable propagation velocity for ultrasound and should only slightly attenuate ultrasound.

[0035] According to another embodiment, the ultrasonic device is a standing wave effect ultrasonic device and / or a near field effect ultrasonic device. In this way, the specific advantages of each method can be fully utilized or even combined. As a result, the load-bearing capacity and self-centering (in the axial direction) can be improved.

[0036] In the case of a standing wave effect ultrasound device, a reflector can be positioned opposite the ultrasound source at a distance that is an integer multiple of a half-wavelength. The emitted ultrasound waves are thus self-reflected, generating standing waves with varying sound velocity and pressure, where the sound velocity nodes correspond to the pressure antinodes. An object, such as a measuring shaft (or at least a portion thereof, such as a shaft element), can then be supported at one of these sound velocity nodes.

[0037] In the case of proximity-effect ultrasound devices, an object, such as a measuring shaft (or at least a portion thereof, such as a shaft element), can be very close to the ultrasound source. This produces an effect similar to that in hydrodynamic bearings, where the gas is compressed in the gap. Because high amplitudes of the actuator (2 to 15 μm) may also be required, depending on the quality and design of the sonotrode, the gap must not be too small (e.g., a distance in the range of 50 to 500 μm).

[0038] According to another embodiment, the electric motor is a rotary (measuring) motor which is provided for rotating the shaft serving as the measuring shaft in the radial direction. This has the advantage that the described device can be directly integrated into the created system.

[0039] According to another embodiment, the motor is a linear (measuring) motor, which is provided for moving the shaft serving as the adjustment shaft in the axial direction, in particular linearly. This has the advantage that a particularly efficient and precise measuring instrument can be provided.

[0040] According to another embodiment, a sample carrier is arranged between the measuring axis and the adjusting axis, in particular, wherein the measuring axis and the adjusting axis are essentially opposite each other when viewed in the axial direction. This can have the advantage that a particularly efficient measuring instrument can be provided, in which, for example, both axes are at least partially supported ultrasonically.

[0041] In the following, reference Figure 8 An embodiment of a corresponding measuring instrument is described, which has a measuring axis and an adjustment axis, with the sample carrier being arranged between the two axes. According to one embodiment, the adjustment axis can be particularly well centered and supported essentially without deflection using an ultrasound source. Furthermore, the measuring axis described above can advantageously be ultrasonically supported, in particular by means of an axis element.

[0042] According to another embodiment, the measuring device also has a measuring unit, in particular a capacitive measuring unit, for measuring the indication information on the shaft element (in particular capacitively). This can have the advantage that the system created can be directly integrated into the described measuring device.

[0043] A corresponding measuring unit may be known to a person skilled in the art. However, in the present context it was completely surprising that the created measuring unit can function efficiently in conjunction with the concept of an ultrasonically supported measuring shaft.

[0044] According to another embodiment, the measuring instrument further comprises a tightly closable (in particular fluid-tight) chamber, such as a pressure chamber, wherein at least a portion of the ultrasound device, at least a portion of the shaft, and the sample carrier are arranged in the tightly closable chamber. In terms of process technology, the measuring instrument is at least partially introduced into the chamber. This has the advantage that very specific measuring conditions can be provided particularly efficiently and without high expenditure.

[0045] In this context, the term "hermetically closed" may particularly mean fluid-tight. The chamber may be used for special measurement conditions, such as particularly high pressures. For this purpose, a pressure chamber may be used, into which the measuring instrument or at least a portion of the measuring instrument is introduced. A pressure profile may be applied to the pressure chamber (e.g., by means of a pressure vessel) to produce a predetermined specific pressure in the chamber.

[0046] According to another embodiment, the measuring device also has a pressure container in order to apply a pressure distribution to the tightly closable chamber. This can have the advantage that a particularly efficient and robust pressure distribution can be achieved in the pressure chamber.

[0047] According to another embodiment, in the method, the tightly closed chamber is at least partially filled with a gas having a density higher than that of air (for example argon). This can have the advantage that the rigidity of the bearing is increased.

[0048] If the entire rheometer (or at least a portion thereof) is placed in a closed space (e.g., a sample chamber), it can be flushed with a gas with a higher density than air. If a particularly high flow rate (e.g., compressed air) is not required, the sample chamber can be flushed with a gas such as argon. This can increase the rigidity of the fluid bearing.

[0049] According to another embodiment, the measuring instrument or at least a portion thereof (e.g., at least a portion of the ultrasonic device, at least a portion of the shaft, and the sample carrier) is used in a special measurement environment. In this regard, the special measurement environment may be, for example, a clean room (or ultra-clean room), a pressure chamber (e.g., a pressure chamber or pressure chamber), an inert environment, or a compressed air decoupling chamber. This list is illustrative and not exhaustive.

[0050] The term "(ultra) clean room" designates a measurement environment in which the (airborne) particle concentration is kept very low. Parameters such as temperature, humidity, and pressure are generally kept constant to ensure comparable conditions at all times. To establish the desired conditions, vacuum pumps, suitable work clothing, and specialized appliances and tools are often used. Clean rooms, especially ultra-clean rooms, can have several classified areas with corresponding clean room classes (e.g., ISO classes).

[0051] In this context, the term "pressure chamber" may designate a pressure-adjustable measuring environment. During operation, such a pressure chamber may be tightly closed (in particular, fluid-tight). Smaller, in particular at least partially movable, units of the pressure chamber may also be referred to as pressure chambers.

[0052] The term "inert environment" can designate a tightly and fluid-tight (or gas-tight) closed measurement environment. In an inert environment, a defined atmosphere can be created for processing sensitive or hazardous materials. For example, an inert environment can be filled with an inert gas (e.g., argon). Thus, an inert environment can be, for example, an argon glove box.

[0053] The term "compressed air decoupling" specifically designates a measurement environment in which no compressed air is used. When measuring in a pressure chamber, the use of additional compressed air leads to numerous technical disadvantages, making a compressed air decoupled environment desirable. Furthermore, the use of compressed air is prohibited on drilling platforms, for example, due to the potential for ignition sparks caused by electrostatic charges. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Next, exemplary embodiments of the present disclosure are described in detail with reference to the following drawings.

[0055] Figure 1 A measuring instrument including a measuring driver provided by an exemplary embodiment of the present disclosure is shown.

[0056] Figure 2 A measuring instrument including a pressure chamber provided by an exemplary embodiment of the present disclosure is shown.

[0057] Figures 3 to 7 Exemplary embodiments of the shaft and ultrasonic device of the present disclosure are shown.

[0058] Figure 8 A measuring instrument including multiple drivers provided by an exemplary embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0059] The same or similar components in different drawings are identified by the same reference numerals.

[0060] Before describing exemplary embodiments of the present disclosure with reference to the accompanying drawings, some general aspects of the present disclosure should be explained:

[0061] According to one exemplary embodiment, supporting the measuring drive in a rheometer via ultrasonic bearings offers the following advantages over conventional air bearings: 1) no need for any "flowing" gas (e.g., compressed air); 2) greater convenience, as no air handling is required; 3) mobile and independent of compressed air availability; 4) usable in completely enclosed environments (e.g., pressure chambers); 5) simpler design (no porous materials required); 6) more robust due to a higher air gap; and 7) lower energy consumption compared to compressed air. Compared to conventional ball bearings, it offers the advantages of lower residual friction and better compensability (constant-angle residual friction curve).

[0062] According to an exemplary embodiment, supporting the measuring drive in the rheometer by means of ultrasonic bearings can provide the following additional advantages: 1) alternative bearing shapes for simpler manufacturability (e.g., double sphere, double cone); 2) combination with capacitive normal force measurement; 3) combination with known drive technologies; 4) measurability (skalier bar) (normal and lateral forces, stiffness); 5) load can be increased by means of alternative gases (e.g., argon); 6) bearing characteristics can be improved by fully utilizing and combining standing wave effects and near-field effects.

[0063] According to an exemplary embodiment, ultrasonic bearings can be used for multi-(multiple) driven rheometers (air bearings have been used so far). At least two (preferably four) ultrasonic sources can be arranged on the axis of the linear motor, which are combined with a flat bracket to hold the measuring axis (linear feed, limited linear offset or oscillating offset). For this purpose, ultrasonic emitters including corresponding horns are installed relative to each other in the air gap. Here, the gap geometry can be optimized so that there is sufficient rigidity for the rheometer. The load-bearing capacity can be enhanced by a higher density gas or by a combination of the lifting and pushing modes of the bearing. On the lower side, the bearings are operated in a repulsive manner in the pushing mode, thereby enhancing the reverse motion relative to gravity. On the upper side, the bearings are operated in a suction manner in the lifting mode. This improves the centering in the rotary bearing.

[0064] According to an exemplary embodiment, the effective torque can be a key parameter for rheological measurements. For motor shafts with an elastic arrangement (e.g., a Brookfield viscometer), the torque can be determined from the rotation angle or measured via the motor current consumption at a specific speed (depending on the motor model, the torque M is related to the current I or I 2 Normal forces or also axial deflections play a central role in dynamic mechanical analyses involving linear deflections, but also in the performance of rotational experiments when the rotational motion additionally generates axial forces (e.g. due to the lap effect).

[0065] Figure 1 A rheometer 101 for determining information indicative of a rheological property (e.g., viscosity) of a sample 150 (in the present case, a liquid) is shown. The measuring instrument 101 includes a measuring drive 100 having a motor 110, a shaft 120, and an ultrasonic device 130. The shaft 120 is coupled to the motor 110 so that it can be driven by the motor 110. Thus, the motor 110 is a rotary motor and can rotate the shaft 120, which serves as a measuring axis. The ultrasonic device 130 is arranged in an axial direction A of the shaft 120 and provides ultrasonic waves, enabling a portion of the shaft 120 to be supported contactlessly by means of ultrasonic waves 135.

[0066] The rheometer 101 has a sample carrier 155 on which a sample liquid 150 can be applied. Here, the shaft 120 is coupled to a measuring element 156 designed as a measuring cone, which covers the sample 150. If the shaft 120 now rotates, the rheological properties of the sample liquid 150, in particular the viscosity, influence the kinematic properties of the rotating shaft 120, in particular its torque and / or angle of rotation and / or normal force N. In order to obtain these measured variables or information indicating the rheological properties of the sample liquid 150. For torque measurement, the prevailing torque can be determined based on the current consumption of the measuring motor, and in order to obtain the normal force N, the rheometer 101 has a measuring unit 161. In the present case, this is a capacitive measuring unit 161, which measures the normal force N in a known manner via a capacitor. The measured data are transmitted to a control unit 160. In addition, the control unit 160 is configured to control or regulate the motor 110. For advantageous measurement, the shaft 120 has a shaft element 125 in the form of a disk, which is arranged on the shaft with its main extension direction perpendicular to the axial direction A of the shaft 120 .

[0067] In the illustrated embodiment, the shaft element 125 is specifically the portion of the shaft 120 that is supported contactlessly by means of an ultrasonic device 130. The ultrasonic device is configured to provide or emit ultrasonic waves 135 so that the shaft element 125 (and thereby also at least partially the shaft 120) is supported in a suspended, particularly frictionless, manner by means of the ultrasonic waves. The ultrasonic device 130 includes four ultrasonic sources 131a, 131b, 131c, and 131d, wherein, viewed in the axial direction A of the shaft 120, two ultrasonic sources 131a and 131b are arranged above the shaft element 125, and two ultrasonic sources 131c and 131d are arranged below it. Furthermore, viewed in the radial direction R of the shaft 120, the two ultrasonic sources 131a and 131c are arranged substantially opposite the other two ultrasonic sources 131b and 131d, with the shaft 120 located therebetween. In the preferred embodiment, the ultrasonic device 130 is provided for contactlessly supporting the shaft member 125 both in the axial direction A and in the radial direction R of the shaft 120. The air gap is filled with a gas having a higher density than air (eg argon) to achieve higher rigidity.

[0068] Figure 2A measuring instrument 201 according to another exemplary embodiment of the present disclosure is shown. The measuring instrument 201 additionally includes a tightly (particularly fluid-tightly) closable chamber 220, here a pressure chamber. A portion of the ultrasound device 130, a portion of the shaft 120b, and a sample carrier 155 containing the sample 150 are disposed in the pressure chamber 220. The measuring instrument 201 includes a pressure vessel 210 for applying a pressure profile to the pressure chamber 220 via a valve 211. For example, the pressure chamber 220 can be pressurized using a hydraulic device or similar apparatus.

[0069] The second portion 120b of the measuring shaft has a magnet 230b at its upper end, which is coupled to the magnet 230a of the first portion 120a of the measuring shaft of the motor 110. The measuring motor 110 rotates the first portion of the shaft 120a via the permanent magnets 230a, and these permanent magnets couple to the magnets 230b on the second portion 120a of the shaft in the closed pressure chamber 220. This embodiment can provide a fluid-tight shape through ultrasonic bearing.

[0070] Figure 3 An exemplary embodiment of a shaft 120 and two shaft elements 125a, 125b is shown. The two shaft elements 125a, 125b are arranged on the shaft 120 and are spatially spaced apart from each other, forming a gap 126 on the shaft 120 between the two shaft elements 125a, 125b. An ultrasonic device 130 includes two ultrasonic sources 131a, 131b arranged opposite each other. Each ultrasonic source 131a, 131b has an emitter 132a, 132b and a sonotrode 133a, 133b, with the sonotrode 133a, 133b pointing toward the region of the shaft 120 where the gap 126 is located. In the direction of sound emission, the sonotrode 133a, 133b is arranged in front of the emitter 132a, 132b. Ultrasonic waves 135 emitted by two ultrasonic sources 131a, 131b are directed from opposite directions toward the gap 126, thereby supporting the two shaft elements 125a, 125b contactlessly. In the illustrated embodiment, both shaft elements 125a, 125b are designed as hemispheres, with the gap 126 being generated between the rounded surfaces.

[0071] Figure 4An exemplary embodiment of a shaft 120 and a shaft element 125 is shown. The shaft element 125 is oriented with its main extension direction perpendicular to the axial direction A of the shaft 120 and is coupled to the shaft. An ultrasonic device 130 is configured to support the shaft element 125 contactlessly both in the axial direction A and in the radial direction R of the shaft 120 by means of emitted ultrasound 135. To this end, the ultrasonic device 130 includes four ultrasound sources 131a-d. As viewed in the axial direction A of the shaft 120, two ultrasound sources 131a and 131b are arranged above the shaft element 125, while two ultrasound sources 131c and 131d are arranged below it. Furthermore, as viewed in the radial direction R of the shaft 120, two ultrasound sources 131a and 131c are arranged opposite the other two ultrasound sources 131b and 131d, with the shaft 120 positioned therebetween.

[0072] Figure 5 An exemplary embodiment of a shaft 120 and an ultrasonic device 130 is shown. The shaft 120 is a measuring or regulating shaft, and two ultrasonic sources 131a, 131b are arranged opposite each other, with the shaft 120 arranged therebetween. In a preferred embodiment, four ultrasonic sources 131a-d (not shown) are arranged opposite each other around the shaft 120. The shaft 120 can be designed to be circular (e.g., rod-shaped), but can also be designed to be rectangular. The ultrasonic waves 135 emitted by the ultrasonic sources 131a, 131b can effectively support the shaft 120 in a specific position.

[0073] Figure 6 Shown above for Figure 5 A top view of an embodiment is shown in which four ultrasound sources 131a-d are arranged around an axis 120. In this exemplary embodiment, each ultrasound source 131a-d has a horn 134 between an emitter 132 and a sonotrode 133.

[0074] Figure 7 An exemplary embodiment of a shaft 120 and an ultrasound device 130 is shown, wherein the ultrasound device 130 is designed as a housing for the shaft 120. In this case, the ultrasound source can be installed in the housing, or the inside of the housing can serve as the ultrasound source.

[0075] Figure 8An exemplary embodiment of a measuring device 800 is shown, which includes a measuring shaft 120 and an adjusting shaft 121. This multi-drive system uses a combination of a linear motor 111, which drives the adjusting shaft 121, and a rotary motor 110, which drives the measuring shaft 120. A common control unit 160 can control or regulate both the rotary motor 110 and the linear motor 111. Furthermore, the control unit 160 can monitor (or regulate) the rotational speed or torque and is connected to an angular encoder 166 and a torque detector 165 for this purpose. A sample carrier 155, into which a sample liquid 150 can be introduced, is arranged between a measuring element 156 at the lower end of the measuring shaft 120 and a measuring element 157 at the upper end of the adjusting shaft 121. Both the measuring shaft 120 and the adjusting shaft 121 may include a clutch 128. On the measuring device plane, the rotary motor 110 is provided in a first support 170 of the measuring device, and the linear motor 111 is provided in a second support 171. The supports 170, 171 are fixed to a bracket 180, and the height of the first carrier 170 relative to the second carrier 171 can be adjusted by means of a servo motor 183 via an adjustment element 181 and an adjustment spindle 182. The cooperation between the rotating measuring axis 120 and the linearly movable adjustment axis 121 enables particularly precise (rheological) measurements.

[0076] The measuring shaft 120 has a shaft element 125 in the form of a disk, as described above. Four ultrasound sources 131a-d are arranged on the sides of the shaft 120 and the shaft element 125, so that the shaft element 125 is supported contactlessly in the axial direction A and the radial direction R of the shaft 120 by means of ultrasonic levitation (see above for this purpose). Figure 4 ). With a similar Figures 5 to 7 In the manner shown in FIG, two (preferably four) ultrasonic devices 130 are arranged around the adjustment shaft 121. The emitted ultrasonic waves 135 ensure that the deflection of the adjustment shaft 121 is limited and the stability is increased.

[0077] It should be noted that "comprising" does not exclude any other elements or steps, and "a" or "an" does not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the embodiments above can also be used in combination with other features or steps of other embodiments described above. Reference numerals in the claims are not to be considered as limitations.

[0078] Reference numerals

[0079] 100, 800 measurement drivers

[0080] 101, 201 measuring instruments, rheometers

[0081] 110 Motors, rotating motors

[0082] 111 Linear Motor

[0083] 120 axis, measuring axis

[0084] 120a First shaft section

[0085] 120b Second shaft section

[0086] 121 Adjustment shaft

[0087] 125 shaft element

[0088] 125a First axis element

[0089] 125b Second axis element

[0090] 126 Gap

[0091] 128 Clutch

[0092] 130 Ultrasound device

[0093] 131a-d Ultrasound Source

[0094] 132a, b emitter

[0095] 133a, b Ultrasonic oscillation unit

[0096] 134 Speaker

[0097] 135 Ultrasound

[0098] 150 samples

[0099] 155 sample carrier

[0100] 156 Measuring elements

[0101] 157 Additional measuring elements

[0102] 160 control unit

[0103] 161 Capacitive measuring unit

[0104] 165 Torque Detector

[0105] 166 Angular Encoder

[0106] 170 First support

[0107] 171 Second support

[0108] 180 bracket

[0109] 181 Adjustment parts

[0110] 182 Adjusting the spindle

[0111] 183 Servo Motor

[0112] 210 Pressure Vessel

[0113] 211 Pressure Valve

[0114] 220 pressure chamber

[0115] 230a, b magnet.

Claims

1. A measuring drive (100) for a rheometer, wherein the measuring drive (100) comprises: Motor (110); a shaft (120) coupled to the motor (110) such that the shaft (120) can be driven by means of the motor (110), wherein the shaft (120) comprises a shaft element (125); and an ultrasonic device (130) configured to provide ultrasonic waves (135) to the shaft (120), so that at least a portion of the shaft (120) can be supported substantially contactlessly by means of the ultrasonic waves (135); It is characterized in that the ultrasonic device (130) is configured to support the shaft element (125) essentially contactlessly both in the axial direction (A) of the shaft (120) and in the radial direction (R) of the shaft (120), wherein at least one of the shaft elements (125) essentially has a shape selected from the following group, the group consisting of a disk, an annular disk, a plate, a truncated cone, a hemisphere or a truncated pyramid.

2. The measuring drive (100) according to claim 1, The ultrasonic device (130) is configured to emit the ultrasonic waves (135), so that at least a portion of the shaft (120) can be supported in a suspended manner by means of the ultrasonic waves (135).

3. The measuring drive (100) according to claim 2, The ultrasonic device (130) is configured to emit the ultrasonic waves (135), so that at least a portion of the shaft (120) can be supported in a frictionless suspension manner by means of the ultrasonic waves (135).

4. The measuring drive (100) according to claim 1, wherein the ultrasound device (130) has at least two ultrasound sources (131) which are arranged substantially opposite to each other, and wherein at least a portion of the shaft (120) is arranged between the substantially opposing ultrasound sources (131).

5. The measuring drive (100) according to claim 1, wherein the shaft element (125) is coupled to the shaft in such a way that its main extension direction is oriented substantially perpendicularly to the axial direction (A) of the shaft (120), and The ultrasonic device (130) is arranged such that the shaft element (125) can be supported in a substantially contactless manner by means of the ultrasonic waves (135).

6. The measuring drive (100) according to claim 1, wherein the ultrasonic device (130) has at least four ultrasonic sources (131), wherein, viewed in the axial direction (A) of the shaft (120), two ultrasound sources are arranged above the shaft element (125), two ultrasound sources are arranged below the shaft element, and Two ultrasound sources are arranged substantially opposite to the other two ultrasound sources, viewed in a radial direction (R) of the shaft (120), with the shaft (120) located therebetween.

7. The measuring drive (100) according to claim 1, wherein the shaft (120) has at least two shaft elements (125) which are spatially spaced apart from one another and thereby form a gap (126), and The ultrasonic device (130) has at least two ultrasonic sources (131), which are arranged substantially opposite to each other so that the emitted ultrasonic waves (135) are at least partially aligned with the gap (126), thereby being able to support at least two shaft elements (125) substantially without contact.

8. The measuring drive (100) according to claim 4, The ultrasonic source (131) has an ultrasonic emitter (132) and an ultrasonic oscillation unit (133). In the direction of sound wave emission, the ultrasonic oscillation unit (133) is arranged before the emitter (132).

9. The measuring drive (100) according to claim 8, The ultrasonic source (131) further comprises a speaker (134), which is arranged between the emitter (132) and the ultrasonic oscillation unit (133).

10. The measuring drive (100) according to claim 1, The ultrasonic device (130) is configured as a standing wave effect ultrasonic device and / or a near field effect ultrasonic device.

11. The measuring drive (100) according to claim 1, The motor (110) is a rotary measuring motor, which is configured to rotate a shaft (120) serving as a measuring shaft in a radial direction (R).

12. The measuring drive (100) according to claim 1, The motor (110) is a linear measuring motor (111) configured to move a shaft (120) serving as an adjustment shaft (121) in an axial direction (A).

13. A measuring instrument (101), the measuring instrument being a rheometer, for determining information indicative of rheological properties of a sample (150), characterized in that The measuring instrument (101) comprises: The measuring drive (100) according to claim 1; A sample carrier (155) for positioning the sample (150), wherein the shaft (120) is coupleable to the positioned sample (150).

14. The measuring instrument (101) according to claim 13, in, The measuring device (101) has an adjustment axis and a measuring axis, and the sample carrier (155) is arranged between the axis (120) serving as the measuring axis and the adjustment axis (121).

15. The measuring instrument (101) according to claim 13, comprising: A measuring unit (161) is used for measuring indication information on the shaft (120).

16. The measuring instrument (101) according to claim 13, further comprising: A tightly closable chamber (220), wherein at least a portion of the ultrasound device (130), at least a portion of the shaft (120), and the sample carrier (155) are arranged in the tightly closable chamber (220).

17. The measuring instrument (101) according to claim 16, further comprising: A pressure container (210) is used to apply pressure distribution to the tightly closed chamber (220).

18. A method of using the measuring instrument (101) according to claim 13 in a special measuring environment.

19. The method according to claim 18, wherein the special measurement environment comprises at least one of an ultra-clean room, a pressure chamber, an inert environment, or a compressed air decoupling chamber.

20. A method for determining information indicative of a rheological property of a sample (150) by means of a measuring instrument (101), wherein the measuring instrument is a rheometer and has a motor (110) and a shaft (120), the shaft (120) including a shaft element (125) and coupled to the motor (110), the method comprising: providing the sample (150), and coupling the shaft (120) to the sample (150); driving the shaft (120) by means of the motor (110) so that the indication information is reflected on the motion characteristics of the shaft (120); By means of an ultrasonic device (130), ultrasonic waves (135) are emitted to the shaft (120), so that at least a portion of the shaft (120) is supported substantially contactlessly by means of the ultrasonic waves (135); and obtaining a motion characteristic of the shaft (120) to determine the indicative information of the rheological properties of the sample (150); It is characterized in that the ultrasonic device (130) is configured to support the shaft element (125) essentially contactlessly both in the axial direction (A) of the shaft (120) and in the radial direction (R) of the shaft (120), wherein at least one of the shaft elements (125) essentially has a shape selected from the following group, the group consisting of a disk, an annular disk, a plate, a truncated cone, a hemisphere or a truncated pyramid.

21. The method according to claim 20, further comprising: At least a portion of the measuring instrument (101), at least a portion of the shaft (120), and the sample (150) are introduced into a tightly closed chamber (220).

22. The method according to claim 21, The tightly closed chamber (220) is at least partially filled with a gas having a density higher than that of air.

23. The method of claim 20, further comprising: Ultrasonic waves (135) are emitted by means of the ultrasonic device (130), so that the shaft element (125) is supported substantially contactlessly in the axial direction (A) and radial direction (R) of the shaft (120), and the shaft element is coupled to the shaft in a manner in which the main extension direction is oriented substantially perpendicular to the axial direction (A) of the shaft (120).

24. Method for substantially contactlessly supporting at least a portion of a shaft (120) in a measuring instrument (101) using an ultrasonic source (131), the measuring instrument (101) being a rheometer, the shaft (120) comprising a shaft element (125), characterized in that The ultrasonic source (131) is configured to support the shaft element (125) in an essentially contactless manner both in an axial direction (A) of the shaft (120) and in a radial direction (R) of the shaft (120), wherein at least one of the shaft elements (125) essentially has a shape selected from the group consisting of a disk, an annular disk, a plate, a truncated cone, a hemisphere or a truncated pyramid.

25. The method according to claim 24, wherein at least a portion of the ultrasound source (131), at least a portion of the shaft (120) and the sample (150) to be examined are arranged in a hermetically closed chamber (220).

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