Measuring cell for rheometer with a contact-free support in a measurement configuration and a gap-free flushing configuration

Abstract

The invention relates to a measuring cell (100) for a rheometer (102). The measuring cell (100) has a sample receiving container (104) for receiving a sample to be measured, a rotary body (106) which is at least partly rotatably arranged in the sample receiving container (104) in order to interact with the sample to be measured, and a controller (108) which is designed to control a relative movement between the rotary body (106) and the sample receiving container (104) such that a gap (110) is formed between the rotary body (106) and the sample receiving container (104) in a measurement configuration in order to arrange the rotary body (106) in the sample receiving container (104) in a mutually contactless manner and such that the gap (110) between the rotary body (106) and the sample receiving container (104) is closed in a liquid-tight manner in a flushing configuration.

Description

[0001] Measuring cell for rheometers with non-contact bearing in measuring configuration and gap-free rinsing configuration

[0002] The invention relates to a measuring cell, a rheometer, and a method for operating a measuring cell for a rheometer.

[0003] Rotational and oscillatory rheometers are instruments used to determine the flow behavior of viscoelastic samples, for example, in rotational, creep, relaxation, and oscillation tests. They can be used to investigate both the flow behavior of liquids and the deformation behavior of solids. The sample material to be tested is placed in a measuring chamber between two measuring parts. The upper or lower measuring part is set in a rotating motion, and the sample is subjected to shear stress by twisting the measuring parts against each other. Both rotating and rotating-oscillating movements are possible.The measuring parts can have different geometries, for example plate-plate measuring systems, concentric cylinder measuring systems, cone-plate measuring systems as well as special arrangements for different application areas, for example for measuring the immobilization behavior of dispersions or building materials, electrorheological measurements, etc.

[0004] Conventional rheometers and other systems are disclosed, for example, in EP 0,211,112, JPS 60133344, US 2004 / 126874, DE 19832881, DD 274279, US 2005 / 132783, CA 2,614,579, US 6,807,849, US 4,077,251, US 2011 / 061451, US 2,266,733, US 3,073,151 and US 3,939,690.

[0005] It is an object of the present invention to determine rheological information in a precise manner.

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

[0007] AD: ml According to one embodiment of the present invention, a measuring cell for a rheometer is provided, wherein the measuring cell has a sample receiving container for receiving a sample to be measured, a rotating body which is rotatably arranged at least partially in the sample receiving container for interaction with the sample to be measured, and a control device which is designed to control a relative movement between the rotating body and the sample receiving container, so that in a measuring configuration a gap is formed between the rotating body and the sample receiving container for contactless mutual arrangement of the rotating body and the sample receiving container, and in a rinsing configuration the gap between the rotating body and the sample receiving container is closed in a liquid-tight manner.

[0008] According to another embodiment of the invention, a rheometer for rheologically measuring a sample is provided, comprising a measuring cell with the features described above.

[0009] According to a further embodiment of the present invention, a method for operating a measuring cell for a rheometer is provided, the method comprising receiving a sample to be measured in a sample receiving container, rotating a rotating body which is arranged at least partially in the sample receiving container to interact with the sample to be measured, forming a gap between the rotating body and the sample receiving container for contactless mutual arrangement of the rotating body and the sample receiving container for measuring the sample, and liquid-tight closing of the gap between the rotating body and the sample receiving container for rinsing the sample receiving container.

[0010] In the context of the present application, a "rheometer" can be understood in particular as an apparatus used to determine the deformation and flow behavior of a sample. In particular, a rheometer can be designed to determine tensile deformations, bending deformations and / or viscosity of a sample to be examined. In the context of the present application, a "measuring cell" can be understood in particular as a component of a rheometer in which the actual measurement is carried out on the sample to be characterized. This component can be integral or, in turn, be constructed from several subcomponents.

[0011] In the context of the present application, the term "sample receiving container" can be understood to mean, for example, a cup-shaped container designed for filling and receiving a sample to be examined. This can in particular be a fluidic or viscous sample, for example a viscous medium, a liquid and / or a gas. Solids (for example, particles or pastes) can also be contained in such a sample or can represent a sample being examined.

[0012] In the context of the present application, the term "rotating body" can be understood in particular as a body that is rotated during measuring operation in order to trigger a mechanical interaction at an interface with the sample to be examined, which allows conclusions to be drawn about the viscosity of the sample. During measuring operation, the rotating body can, for example, be rotated about its own axis and, in doing so, interacts on its side surface with the sample in the sample receiving container in which the rotating body is arranged, at least during measuring operation and at least partially. The rotating body can also be subjected to another movement, for example an oscillation movement and / or a lifting or lowering movement.

[0013] In the context of the present application, the term "control device" can be understood in particular as a control or regulation that can control or regulate a drive device that can drive the rotating body and / or at least one other component of the measuring cell. For example, such a control device can comprise a computer, a processor, part of a processor, or a plurality of processors. The control device can also control or regulate the entire operation of the rheometer or the measuring cell. For example, such a control device can be software-controlled. In addition to controlling the movement of a rotating body, the control device can also, for example, also take over valve control, etc.

[0014] In the context of the present application, the term "measurement configuration" can be understood in particular as an operating mode of the measuring cell or rheometer in which rheological information about the sample to be measured is recorded. During measurement operation, a gap (in particular an annular gap) between the rotating body and the sample receiving container ensures that any frictional influence on the rotating body occurs exclusively or at least almost exclusively through an interaction of the sample to be measured with the rotating body, whereas direct friction effects between the rotating body and the sample receiving container, which could undesirably influence the measurement, are achieved by the contactless, gap-based decoupling of the rotating body and the sample receiving container in the measurement configuration.

[0015] In the context of the present application, the term "flushing configuration" can be understood in particular as an operating mode of the measuring cell or rheometer that differs from the measuring configuration and in which the interior of the sample receiving container can be flushed with a flushing medium. This flushing medium can in particular be at least one flushing fluid, in particular a flushing liquid and / or a flushing gas. In order to be able to carry out the flushing process in a contamination-free and at the same time intensive manner, the gap maintained in the measuring configuration between the measuring body and the sample receiving container is closed in the flushing configuration, so that a liquid-tight interface is created between the rotating body and the sample receiving container.

[0016] According to an exemplary embodiment of the invention, a measuring cell for a rheometer is provided in which, in a measuring configuration or during measuring operation, a sample is filled into the sample receptacle, which is subjected to a targeted frictional interaction with the rotating body rotating in the sample receptacle. In other words, in the measuring configuration, direct physical contact is brought about between the sample to be measured and the rotating body. The resulting damping of the rotational movement then depends on the properties of the sample to be measured. Advantageously, a gap is maintained between the rotating body and the sample receptacle in the measuring configuration, in particular an air gap.This ensures that the rotating body is mounted without contact with the sample container, so that friction at an interface directly between the rotating body and the sample container is advantageously avoided. It is particularly advantageous that a control device closes the gap between the rotating body and the sample container in a liquid-tight manner and therefore seals it when the measuring cell is transferred from the described measuring configuration to a rinsing configuration. This means that any rinsing fluid (for example a liquid and / or a gas) can be rinsed through the sample container at high pressure without it escaping between the rotating body and the sample container and thus causing contamination. Before a measurement or after a rinsing process, the control device can open or reopen the gap between the rotating body and the sample container.The described configuration enables both high-accuracy rheological measurement and efficient and reliable flushing. This reliably prevents unwanted sample carryover between measurements and allows the rheological information of a sample to be determined with high accuracy.

[0017] Additional exemplary embodiments of the measuring cell, the rheometer, and the method are described below. According to one exemplary embodiment, the sample container can be a beaker. Such a beaker can be closed at the top by a cap, through which the rotating body can be passed either with or without a gap.

[0018] According to an exemplary embodiment, the sample container can comprise a base and a lid that can be releasably connected to one another, in particular by means of a screw cap or a bayonet lock. Both a screw cap and a bayonet lock allow a fluid-tight coupling of the cup and lid. However, other detachable connection mechanisms between the base and lid are also possible. Advantageously, a seal (e.g., an O-ring) can be provided between the base and lid to further improve the reliability of the fluid-tightness of the sample container.

[0019] According to an exemplary embodiment, the sample receptacle can have a sample inlet for admitting the sample to be measured and a sample outlet for discharging the measured sample. Thus, the sample receptacle can have an inlet for the sample and a sample outlet. Preferably, the sample inlet and sample outlet can be selectively opened or closed, for example, by means of valves. This can be controlled, for example, by the control device.

[0020] According to an exemplary embodiment, the sample inlet can open further down into a sample receiving volume of the sample receiving container than the sample outlet. It has proven advantageous for the measurement if the sample flows from bottom to top as it passes through the sample receiving container. This can also suppress undesirably strong sample outflow and ensure a minimum sample fill level. According to an exemplary embodiment, the sample receiving container can have a rinsing agent inlet for admitting a rinsing fluid. The rinsing agent inlet can be provided as a third fluid interface of the sample receiving container. Alternatively, rinsing fluid can also be supplied through the sample inlet, so that only two fluid interfaces are possible.However, if the rinsing agent inlet is provided separately from the sample inlet, its positioning can be optimized for the supply of rinsing fluid, resulting in particularly good rinsing results. Supplying rinsing medium from the top of the sample container ensures that essentially the entire volume of the sample container is rinsed and thus cleaned.

[0021] According to an exemplary embodiment, the rinsing agent inlet can open higher into the sample receiving volume of the sample receiving container than the sample inlet and / or the sample outlet. It has proven advantageous if the rinsing agent inlet is arranged higher than the sample inlet, preferably higher than the sample inlet and the sample outlet. This allows the rinsing agent flow and sample flow to be spatially decoupled from each other. Further advantageously, the rinsing agent inlet can be arranged higher in the sample receiving container than the desired height of the sample to be measured when it is inserted into the sample receiving volume.

[0022] According to an exemplary embodiment, the control device can be configured to measure the sample to be measured in the flow-through or to measure it statically in the measuring configuration. According to one embodiment, the sample to be measured is thus continuously pumped through the sample receiving container during the measurement. Alternatively, the sample to be measured can be introduced into the sample receiving volume and the measurement then started. Only after the measurement has ended is the sample to be measured released from the sample receiving container through the sample outlet. According to an exemplary embodiment, the control device can be configured to convey a flushing fluid in the flow-through through the sample receiving container in the flushing configuration.For example, such a rinsing fluid can be introduced under pressure into the interior of the sample container in order to ensure reliable rinsing and cleaning of the inner wall of the sample container.

[0023] According to an exemplary embodiment, the control device can be configured to raise or lower one of the rotating body and the sample receiving container and to hold the other of the rotating body and the sample receiving container stationary in order to transfer the rotating body and the sample receiving container between the measuring configuration and the rinsing configuration. The control device can therefore move the rotating body and leave the sample receiving container static in order to transfer the measuring cell between the measuring configuration and the rinsing configuration, or vice versa. It is also possible to move both the sample receiving container and the rotating body relative to one another during said transition between the configurations. In all of these configurations, it is possible to selectively open or close the gap between the rotating body and the sample receiving container in a simple manner.Preferably, a drive device used to rotate the rotating body during measurement operation can also be used for the longitudinal movement of the rotating body and / or sample receiving container for transferring between the measurement configuration and the rinsing configuration. Alternatively, however, it is also possible for a first drive device to be used to drive the rotating body in rotation in the measurement configuration, and a separate second drive device to effect the relative movement between the rotating body and sample receiving container for transferring between the measurement configuration and the rinsing configuration.

[0024] According to an exemplary embodiment, in the measuring configuration between the rotating body and the sample receiving container, the gap can be formed between a conical body of the rotating body and a conical receptacle of the sample receiving container (see, for example, Figure 1 or Figure 4). Forming an annular gap between a conical receptacle of the sample receiving container and a conical body of the rotating body is a particularly suitable geometric configuration for reliably and selectively opening or closing the gap. In the gap-free state, two conical surfaces thus lie sealingly against one another. In this context, automatic self-alignment between the conical body and the conical receptacle is advantageously enabled, for example if the conical body is lowered slightly offset from the conical receptacle.

[0025] According to another exemplary embodiment, in the measurement configuration between the rotating body and the sample receiving container, the gap can be formed between a plate body of the rotating body and a plate receptacle of the sample receiving container (see, for example, Figure 5). A reliable opening or closing of the gap can also be achieved selectively between two plates.

[0026] According to an exemplary embodiment, a seal, in particular an O-ring, can be arranged between the rotating body and the sample receiving container. If a seal, for example an O-ring, is provided between the corresponding bodies between which the gap is to be formed or closed, particularly reliable fluid tightness can be ensured in the purging configuration. This is advantageous, for example, when an aggressive purging medium or a highly volatile purging medium, such as a purge gas, is used. Such a purging medium can then be reliably prevented from escaping and contaminating the surroundings of the measuring cell.

[0027] According to an exemplary embodiment, the control device can be configured to automatically measure a plurality of samples to be measured sequentially in the measurement configuration and to automatically rinse the sample receiving container in the rinsing configuration between at least some of the sequential measurements. With the described configuration of the control device, it is possible to completely or at least almost completely automate a sample measurement process and reliably prevent sample carryover. For example, a user only needs to provide an array of samples to be measured one after the other, which are then filled into the sample receiving container in a measurement configuration and measured there.Between two consecutive sample measurements or at other intervals, the control unit can then transfer the measuring cell to the purge configuration to remove sample residues from the sample collection container and thus prevent unwanted carryover of historical samples. This contributes to measurement accuracy while ensuring high sample throughput when measuring a large number of samples.

[0028] According to an exemplary embodiment, the control device can be configured to sequentially flush the sample container using a plurality of flushing fluids in the flushing configuration. In particular, the sequential flushing using a plurality of flushing fluids can be performed using one or more flushing fluids and at least one flushing gas. The plurality of flushing fluids can thus contain different flushing fluids, for example, an organic and an inorganic solvent. It is also possible to combine a flushing fluid with a flushing gas (for example, compressed air) to achieve particularly good flushing results.

[0029] According to an exemplary embodiment, the rheometer can have a drive device for rotating the rotating body in the measuring configuration and / or for raising or lowering the rotating body relative to the sample receiving container for transferring between the measuring configuration and the rinsing configuration. Said drive device can be an electric motor, for example. It is also possible to provide two drive devices, for example, one below the measuring cell and the other above the measuring cell. The at least one drive device can be mechanically connected to the rotating body, preferably via a rotating shaft. It is also possible for a drive device to accomplish at least one further movement mode, for example, an oscillation of the rotating body, in addition to rotating the rotating body and raising / lowering the rotating body and sample receiving container relative to one another.

[0030] According to an exemplary embodiment, the rheometer can have a determination device for determining rheological information regarding the sample to be measured based on an analysis of the drive energy applied by the drive device to rotate the rotating body interacting with the sample to be measured. If a sample to be measured has a relatively high viscosity, it will inhibit the rotating body's rotational movement more strongly upon interaction with the rotating body than with another sample with a comparatively low viscosity. Detecting the required drive energy, for example, to rotate the rotating body at a desired speed or at a desired frequency, therefore allows conclusions to be drawn about the rheological properties (in particular the viscosity) of the sample to be measured.

[0031] According to an exemplary embodiment, the rheometer can comprise a sensor device for acquiring sensor data indicative of rheological information regarding the sample to be measured, in particular on a rotational axis between the drive device and the rotating body. Such a sensor device can be arranged, for example, on a rotational axis in order to characterize the rotational properties. Such a sensor arrangement can perform a force, stress, and / or load measurement. For example, such a sensor arrangement can be designed as a strain gauge or as an optical sensor. Exemplary embodiments of the present invention are described in detail below with reference to the following figures.

[0032] Figure 1 shows a cross-sectional view of a measuring cell of a rheometer according to an exemplary embodiment of the invention.

[0033] Figure 2 shows a cross-sectional view of a detail of the measuring cell of the rheometer according to Figure 1.

[0034] Figure 3 shows a cross-sectional view of a rheometer according to an exemplary embodiment of the invention.

[0035] Figure 4 shows a cross-sectional view of a measuring cell of a rheometer according to an exemplary embodiment of the invention.

[0036] Figure 5 shows a cross-sectional view of a measuring cell of a rheometer according to an exemplary embodiment of the invention.

[0037] Figure 6 shows a cross-sectional view of a measuring cell of a rheometer according to an exemplary embodiment of the invention.

[0038] The same or similar components in different figures are provided with the same reference numerals.

[0039] Before exemplary embodiments of the invention are explained in more detail with reference to the figures, some general considerations are described on the basis of which exemplary embodiments of the invention were found.

[0040] According to an exemplary embodiment of the invention, a rheometer or a measuring cell for a rheometer is created in which a control device can selectively switch back and forth between a measuring configuration for measuring a sample to be characterized with regard to its properties and a rinsing configuration for rinsing a sample receiving container before or after a measurement. Advantageously, the control device for the measuring configuration can form a gap between the sample receiving container and a rotating body rotating therein and in physical contact with the sample to be measured while the measurement is being taken. This enables contactless rotation of the rotating body without physical contact with the sample receiving container, so that frictional effects directly between the rotating body and the sample receiving container are avoided and therefore do not undesirably impair the measurement.Advantageously, by moving the rotating body and / or the sample container for a flushing configuration, the gap between the two components can be sealed, allowing flushing fluid—even aggressive—to be flushed through the sample container, even at high pressure or throughput, without the risk of contamination. This enables fast and effective flushing and prevents sample carryover. Advantageously, the control of the measuring cell can be fully automated in both the measuring and flushing configurations.

[0041] A core of an embodiment of the invention thus consists in the provision of a measuring cell for a rheometer in which a rotating body of revolution is fed through a cup-shaped sample container, for example, which is designed in such a way that the arrangement can be sealed for cleaning or rinsing. Cleaning with any solvent is then possible without risk. A gap between the rotating body and the sample container can be selectively opened or closed for this purpose. For measuring, the gap is opened to ensure contact-free storage of the rotating body in order to avoid the measurement being affected by artifacts due to a frictional connection between the rotating body and the sample container. For cleaning, the sample container can be lowered and / or the rotating body can be raised, so that the gap between the sample container and the rotating body is temporarily closed for cleaning.To open the gap, an inverse movement can be performed.

[0042] Some embodiments may make it possible to operate a rheometry cell inline or with an autosampler, even without a robotic arm. Advantageously, it may be possible to measure an entire magazine of samples automatically.

[0043] One difficulty overcome by embodiments of the invention has traditionally been the cleaning of a rheometer's measuring cell. By alternately opening the measuring cell for measurement and closing it for cleaning, it is possible to rinse it both with pressure and / or at elevated temperature, as well as with aggressive cleaning agents. According to exemplary embodiments of the invention, manual cleaning of the rheology cell can advantageously be dispensed with.

[0044] This has advantages: Firstly, it enables simple and partially or fully automated sample preparation, cleaning, and at least partially automated sample changes. Furthermore, simple and partially or fully automated measurements are possible. This can increase efficiency or reduce the measurement effort. Furthermore, it can enable the measurement of sample behavior under controlled admixture of other substances in real time, namely during a measurement. This allows an expansion of the application spectrum for rheometers. Compared to conventional approaches, embodiments of the invention allow for an increase in throughput, an improvement in accuracy, a reduction in the complexity of the rheological measurement, and a reduction in effort (particularly due to the possibility of performing an automated measurement even without robots).

[0045] In particular, a measuring cell according to an exemplary embodiment of the invention can be configured as a flow cell, which simplifies the performance of rheological measurements by partially or completely automating the sample preparation, cleaning and / or sample change and thus makes it more efficient.

[0046] A measuring cell according to an exemplary embodiment of the invention has a sample container in the form of a cup with a tight screw lid, which can be slipped over the measuring system and screwed onto the cup before coupling. The upper opening, which can be provided for the passage of a shaft of the measuring system, can be sealed for filling by docking a correspondingly conical formation onto the shaft of the measuring system by raising it. The filling level can be observed or determined, for example, via a software display of the normal force and via the outlet connection. It is also possible to automatically track and / or adjust the filling level. After filling, the measuring system can be lowered to a measuring position. Subsequently, a measurement, for example a standardized measurement, can be carried out, preferably automatically.

[0047] According to one embodiment, cleaning and / or drying can be accomplished by introducing compressed air into a sample container. For example, the introduction of compressed air can occur after a one- or two-component cleaning with liquids (e.g., first heptane, then water and / or acetone, then blow-drying). An outlet at the bottom can be configured with a conical outflow. Furthermore, a conical measuring body can be used. A closure between a cup and a lid of the sample container can be realized, for example, as a bayonet lock or screw cap.

[0048] Figure 1 shows a cross-sectional view of a measuring cell 100 of a rheometer 102 (see Figure 3) according to an exemplary embodiment of the invention. Figure 2 shows a cross-sectional view of a detail 150 of the measuring cell 100 of the rheometer 102 according to Figure 1.

[0049] The measuring cell 100 shown has a rotating body 106 which is rotatably arranged in a sample receiving container 104 for interaction with a sample to be measured. A sample to be measured is therefore filled into the sample receiving container 104 so that it surrounds a cylindrical base section 158 with an end cone 156 of the rotating body 106 with direct physical contact. When the rotating body 106 rotates, driven by a drive device 136, the sample to be measured inhibits the rotation of the rotating body 106 in a characteristic manner depending on its viscosity and its other physical properties. This provides information about the properties of the sample. A rotation of the rotating body 106 about its axis during measuring operation is indicated in Figure 1 by a rotation arrow 152. Furthermore, the rotating body 106 can also be rotated upwards or downwards in the axial direction by means of the drive device 136 (or by means of another drive device, not shown).be moved downwards, as shown by a double arrow 154 in Figure 1.

[0050] A control device 108 controls the drive device 136 and thus serves to control an axial relative movement between the rotating body 106 and the sample receiving container 104 (see double arrow 154). Furthermore, the control device 108 can also control the rotating body 106 to rotate using the drive device 136 (see rotation arrow 152). According to Figure 1, the sample receiving container 104 is a stationary part, while the rotating body 106 is a rotating part that can be raised or lowered vertically. Alternatively, different control devices (not shown) can be used for the two movement modes according to reference numerals 152, 154.

[0051] In particular, the control device 108 is designed to form a gap 110, more precisely an annular gap, between the rotating body 106 and the sample receiving container 104 in a measurement configuration in which a sample is being measured, for the contactless mutual arrangement of the rotating body 106 and the sample receiving container 104. While a sample is being measured in the rheometer 102, the control device 108 ensures that the gap 110 is opened and remains open by correspondingly lowering the rotating body 106 into and relative to the sample receiving container 104. This prevents an undesired influence on the force ratios between the sample and the rotating body 106 during the measurement operation by preventing a frictional force acting directly between the rotating body 106 and the sample receiving container 104 through the gap 110.Furthermore, the control device 108 is designed to seal the gap 110 between the rotating body 106 and the sample receiving container 104 in a fluid-tight manner in a flushing configuration, as shown in Figure 2. Before and / or after measuring a sample in the rheometer 102, the interior of the sample receiving container 104 can be cleaned by flushing with a flushing medium. This prevents contamination or carryover of a sample. By closing the gap 110 for the flushing configuration by lifting the rotating body 106 (preferably fluid-tight), the flushing medium cannot escape from the sample receiving container 104 during flushing. This enables effective flushing with aggressive chemicals and / or under high pressure without any leakage of flushing medium or endangering a user.

[0052] According to Figures 1 and 2, the sample container 104 has a base 112 and a lid 114, which can be releasably connected to one another to form a cup. For this purpose, a screw cap 142 can be formed between the base 112 and the lid 114.

[0053] Furthermore, the sample receptacle 104 can have a sample inlet 116 for admitting the sample to be measured before or during the measurement operation. The sample can be drained from the sample receptacle 104 after it has been measured through a sample outlet 118. A possible fill level of the sample during the measurement operation is shown by reference numeral 170. According to Figures 1 and 2, the sample inlet 116 and the sample outlet 118 open into the sample receptacle 104 at a bottom.

[0054] Furthermore, the sample receptacle 104 includes a rinsing agent inlet 122 for admitting a rinsing fluid during rinsing operation. According to Figure 1, the rinsing agent inlet 122 is mounted on a top side of the sample receptacle 104. Thus, the rinsing agent inlet 122 opens further up into the sample receiving volume 120 of the sample receptacle 104 than the sample inlet 116 and the sample outlet 118. The rinsing inlet 122 can also serve as an overflow if too much sample has been introduced.

[0055] The control device 108 can be designed to measure the sample to be measured in the flow-through mode in the measuring configuration according to Figure 1. This means that during the measurement, sample is continuously admitted through the sample inlet 116 and discharged through the sample outlet 118. Alternatively, the control device 108 can operate the measuring cell 100 in a static measuring mode in which, before the measurement, sample is filled into the sample receiving container 104 through the sample inlet 116 and the sample is only discharged again through the sample outlet 118 after the measurement has been completed. The sample receiving container 104 can therefore be designed, for example, as a flow-through measuring cell. This can measure with a continuous flow of sample. Alternatively, static operation is also possible, i.e., sample is admitted, measured after admission, and then sample is discharged after the measurement has been completed.

[0056] In the flushing configuration according to Figure 2, the control device 108 conveys a flushing fluid or a sequence of successively used flushing fluids through the sample receiving container 104. Preferably, the control device 108 is configured to flush the sample receiving container 104 sequentially using multiple flushing fluids in the flushing configuration. For example, the sequential flushing using multiple flushing fluids can be performed using one or more flushing liquids and one or more flushing gases. If the gap 110 is closed in the flushing configuration by raising the rotating body 106, this promotes operational reliability, as an undefined outflow of the flushing fluid from the sample receiving container 104 is prevented.If the rotating body 106 strikes a counter surface on the upper neck of the sample receiving container 104, a reliable sealing of the gap 110 can be achieved - further promoted by a circumferential seal 134 (for example, an O-ring). More precisely, a seal 134, designed here as an O-ring, can be arranged between the rotating body 106 and the sample receiving container 104. As further shown in Figure 1, alternatively or additionally, a seal 134 (also designed as an O-ring, for example) can be provided between the lower part 112 and the lid 114, which seals the sample receiving container 104 in the region of the screw connection 142. The respective seal 134 can preferably be designed as an annular seal in order to seal continuously in the circumferential direction.

[0057] As already explained, the control device 108 can be configured to raise or lower the rotating body 106 relative to the static or stationary sample receiving container 104 in order to transfer the arrangement of the rotating body 106 and the sample receiving container 104 between the measuring configuration and the rinsing configuration. Alternatively, the rotating body 106 can remain at a constant height and the sample receiving container 104 can be raised or lowered in order to selectively open or close the gap 110.

[0058] According to the measurement configuration shown in Figure 1, with the illustrated geometry of rotating body 106 and sample receptacle 104, the gap 110 is formed between a conical body 126 of rotating body 106 and a corresponding conical receptacle 128 of sample receptacle 104 between rotating body 106 and sample receptacle 104. Starting from the cylindrical base section 158 above the end cone 156, rotating body 106 extends further upward in the form of a shaft 160, to which conical body 126 is connected. Shaft 160 of rotating body 106 can also be referred to as the measuring axis. According to Figure 1, rotating body 106 can be rotationally symmetrical.

[0059] Using the illustrated configuration of the measuring cell 100, it is then possible, under the control of the control device 108, to automatically measure a plurality of samples to be measured sequentially in the measuring configuration and to rinse the sample receiving container 104 between successive sequential measurements (or at a different rhythm) in the rinsing configuration. More precisely, a sample can first be automatically collected into the sample receiving container 104 and measured. After the sample has been drained from the sample receiving container 104, the measuring cell 100 can be automatically transferred from the measuring configuration to the rinsing configuration by closing the gap 110. The interior of the sample receiving container 104 can then be automatically rinsed. Subsequently, the gap 110 can be opened, and the next sample can be automatically introduced into the sample receiving container 104 and measured, etc.In this way, automated measurement of a large number of samples is possible without significant time expenditure or the risk of sample carryover.

[0060] As shown in Figure 1, a sample receiving volume 120 is formed inside the sample receiving container 104, into which the rotating body 106 extends. During operation, the rotating body 106 rotates when the drive device 136 (for example, an electric motor) generates a rotational force under the control of the control device 108 (for example, a processor). After the lower part 112 and the lid 114 have been screwed together using the screw connection 142, a sample to be analyzed can be filled into the sample receiving volume 120 through the sample inlet 116. For this purpose, an inlet valve 164 can be temporarily opened. Only after a measurement is the measured sample discharged from the sample receiving volume 120 through the sample outlet 118 by opening an outlet valve 166. Such operation is referred to as static operation. Alternatively, sample can be pumped continuously or dynamically through the sample intake volume 120 during measurement operation.

[0061] During the measurement, the rotating body 106 rotates, driven by the drive device 136. This subjects the sample to be measured, which is in physical contact with the outer surface of the rotating body 106, to a shear stress. Depending on the viscosity and other properties of the sample, this tends to inhibit the rotation of the rotating body 106. By measuring the required drive energy (for example, to maintain a certain rotation frequency), information about the viscosity and / or other properties of the sample can be obtained. During the measurement operation, the control device 108 controls the measuring cell 100 such that the gap 110 shown in Figure 1 between the rotating body 106 and the sample receiving container 104 is maintained. This enables contactless measurement operation in which no direct friction occurs between the rotating body 106 and the sample receiving container 104.After a measurement, the sample receiving volume 120 inside the sample receiving container 104 can be rinsed or cleaned to prepare it for a subsequent measurement without the risk of sample carryover between different measurements. Preferably, the rinsing fluid or a sequence of different rinsing fluids (e.g., aggressive rinsing liquids and / or rinsing gas) is introduced through the rinsing agent inlet 122 and removed from the sample receiving volume 120, for example, through the sample outlet 118. A rinsing valve 168 can be temporarily opened to admit rinsing fluid, preferably under the control of the control device 108.In order to pump flushing fluid at high pressure through the sample receiving volume 120 and simultaneously avoid contamination of the surroundings of the measuring cell 100 with flushing fluid, the control device 108 controls the drive device 136 (or another drive device not shown) such that the rotating body 106 is pulled upward in the flushing configuration relative to Figure 2. As a result, the gap 110, which is formed between the rotating body 106 and the sample receiving container 104 in the measuring configuration shown in Figure 1, is sealed in a liquid-tight or even gas-tight manner. Flushing can then begin as described.

[0062] Figure 2 shows a detail 150 illustrating the purge inlet 122 and a gap-free configuration between the rotating body 106 and the sample container 104 in the purge configuration. During measurement operation according to Figure 1, the rotating body 106 is supported by air due to the gap 110. The gap 110 is selectively sealed during purge operation according to Figure 2. A seal 134, for example, an O-ring or several O-rings, is also used for this purpose.

[0063] Figure 1 shows only control device 136 as the top-side measuring motor. Alternatively, it is also possible to install two measuring motors, for example, one top-side measuring motor and one bottom-side measuring motor. Reference numeral 172 in Figure 1 indicates a connection for a possible second motor. Furthermore, it is possible to implement a separate measuring motor and a separate rotary motor. According to Figure 1, the current consumption of drive device 136 is used to determine the viscosity of the sample to be measured. As can be seen, drive device 136 according to Figure 1 serves simultaneously as a drive and measuring motor. Alternatively or additionally, information about the properties of the sample can also be obtained from a sensor device 140, for example, from an angle measurement and / or a normal force measurement. A determination device 138 can evaluate the measurement data and determine the properties of the sample therefrom.

[0064] Figure 3 shows a cross-sectional view of a rheometer 102 according to an exemplary embodiment of the invention. More specifically, Figure 3 illustrates the structure of a rotational viscometer.

[0065] The illustrated rheometer 102 is used for the rheological measurement of a sample 176 and can have a measuring cell 100 according to Figure 1. In particular, a drive device 136 is provided for rotating a rotating body 106 when the measuring point 100 is in the measuring configuration. A determination device 138 functions to determine rheological information regarding the sample to be measured based on the drive energy applied by the drive device 136 to rotate the rotating body 106 interacting with the sample 176 to be measured. A sensor device 140 is used to acquire sensor data indicative of rheological information regarding the sample 176 to be measured and can be positioned for this purpose on a drive shaft 174 or rotational axis between the drive device 136 and the rotating body 106.

[0066] The rheometer 102 has the drive device 136, designed here as a measuring motor, which rotates the rotating body 106 via the drive shaft 174. The drive device 136 has the property that the relationship between the torque at the motor axis and the electrical supply, in particular the current consumption, frequency, or phase position, of the drive device 136 is known. This allows the torque of a sample 176 to be determined during a rotation test by measuring the electrical supply parameters. Furthermore, an angle encoder can be provided to determine the rotational position and speed of the drive shaft 174. The drive shaft 174 can be guided in a bearing 180. Depending on the design and the required torque resolution, rolling bearings or, as shown in the present case, an air bearing are used as the bearing 180.

[0067] According to various embodiments of the invention, different measuring systems with standardized geometries can be used. These different measuring systems include, for example, a cone / plate measuring system, a plate / plate measuring system, and a cylinder measuring system.

[0068] Furthermore, the rheometer 102 comprises a dimensionally stable stand 182, which supports the drive device 136 and the bearing(s) 180. Furthermore, the sample receiving container 104, which accommodates the sample 176 and the rotating body 106, is also arranged in the stand 182. The sample receiving container 104 can optionally be assigned a temperature control system for thermostatting the sample 176. The sample receiving container 104 according to Figure 3 can, for example, be designed as shown in Figure 1 or Figure 4.

[0069] To determine the sample parameters, it is possible, for example, to apply a constant speed to the drive shaft 174 and measure the torque. It is also possible to apply a constant torque to the drive shaft 174 and measure the speed or rotational position. Finally, the drive shaft 174 can be subjected to a sinusoidal or other wave-shaped rotational movement (which can be referred to as an oscillation test). In this latter test procedure, the elastic component of the sample 176 can be determined in addition to the viscous component.

[0070] Samples 176 that can be examined include, for example, liquids, gels, pastes, melts, and even solids, especially solid granules or powders. When the rotating body 106 rotates, the sample 176 is sheared, and the viscosity values ​​of the sample 176 can be determined from the rotational speed, the torque, and the gap geometry. A temperature distribution that is as homogeneous as possible within the sample 176 is advantageous for an accurate determination of the viscosity. Furthermore, a precise measurement of the temperature of the sample 176 is advantageous.

[0071] Figure 3 shows a rheometer 102 into which the measuring cell 100 according to Figure 1 or Figure 2 can be integrated. The illustration in Figure 3 is simplified, so that only some of the components of the measuring cell 100 from Figure 1 and Figure 2 are shown.

[0072] Figure 4 shows a cross-sectional view of a measuring cell 100 of a rheometer 102 according to an exemplary embodiment of the invention. The measuring cell 100 according to Figure 4 is designed as a flow cell for a cylinder measuring system and has a cup with a tight screw lid for filling. More precisely, Figure 4 shows a sample receiving container 104 with a rotating body 106 arranged therein, in which a lid 114 can be connected to a lower part 112 by means of a bayonet or screw closure 142 to form a cup. Two seals 134, designed here as O-rings, serve to seal between the lower part 112 and the lid 114 and to seal the adjustable gap 110 in a flushing configuration. More precisely, the gap 110 can be set greater than zero in a measuring configuration and set to zero in a flushing configuration.

[0073] Figure 5 shows a cross-sectional view of a measuring cell 100 of a rheometer 102 according to another exemplary embodiment of the invention. The embodiment according to Figure 5 differs from the embodiment according to Figure 1 in particular in that, according to Figure 5, in the measuring configuration between the rotating body 106 and the sample receiving container 104, the gap 110 is formed between a plate body 130 of the rotating body 106 and a plate receptacle 132 of the sample receiving container 104. While according to Figure 1 two conical bodies form or close an annular gap, the configuration according to Figure 5 uses two plate-shaped bodies.

[0074] Figure 6 shows a cross-sectional view of a measuring cell 100 of a rheometer 102 according to another exemplary embodiment of the invention. Figure 6 shows the measuring cell 100 in the cleaning or rinsing configuration with gap 110. The embodiment according to Figure 6 differs from the embodiment according to Figure 1 in particular in that Figure 6 shows a measuring cell 100 for a plate-on-plate rheometer. In this plate-on-plate rheometer, the measuring fluid is located between two coaxial, circular plates 131, 133, one of which (for example, plate 133) rotates. The measurement and / or control can be carried out via torque and / or speed.

[0075] Figure 6 also shows that a removable needle 135 can extend into the sample receiving volume 120 through a septum or valve 137 to introduce a sample to be measured. The measuring cell 100 according to Figure 6 can be combined with an autosampler.

[0076] Additionally, it should be noted that "comprising" does not exclude 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 above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims are not to be considered as limitations.

Claims

Patent claims 1. A measuring cell (100) for a rheometer (102), the measuring cell (100) comprising: a sample receiving container (104) for receiving a sample to be measured; a rotating body (106) which is rotatably arranged at least partially in the sample receiving container (104) for interacting with the sample to be measured; and a control device (108) which is designed to control a relative movement between the rotating body (106) and the sample receiving container (104), such that: in a measuring configuration, a gap (110) is formed between the rotating body (106) and the sample receiving container (104) for the contactless mutual arrangement of the rotating body (106) and the sample receiving container (104); and in a rinsing configuration, the gap (110) between the rotating body (106) and the sample receiving container (104) is closed in a liquid-tight manner.

2. Measuring cell (100) according to claim 1, wherein the sample receiving container (104) is a cup.

3. Measuring cell (100) according to claim 1 or 2, wherein the sample receiving container (104) has a lower part (112) and a lid (114) which can be releasably connected to one another, in particular by means of a screw cap (142) or by means of a bayonet closure.

4. Measuring cell (100) according to one of claims 1 to 3, wherein the sample receiving container (104) has a sample inlet (116) for admitting the sample to be measured and a sample outlet (118) for discharging the measured sample.

5. Measuring cell (100) according to claim 4, wherein the sample inlet (116) opens further down into a sample receiving volume (120) of the sample receiving container (104) than the sample outlet (118).

6. Measuring cell (100) according to one of claims 1 to 5, wherein the sample receiving container (104) has a rinsing agent inlet (122) for admitting a rinsing fluid.

7. Measuring cell (100) according to claims 4 and 6, wherein the rinsing agent inlet (122) opens further up into the sample receiving volume (120) of the sample receiving container (104) than the sample inlet (116) and / or the sample outlet (118).

8. Measuring cell (100) according to one of claims 1 to 7, wherein the control device (108) is designed to measure the sample to be measured in the flow or to measure it statically in the measuring configuration.

9. Measuring cell (100) according to one of claims 1 to 8, wherein the control device (108) is designed to convey a rinsing fluid in the flow through the sample receiving container (104) in the rinsing configuration.

10. Measuring cell (100) according to one of claims 1 to 9, wherein the control device (108) is designed to raise or lower one of the rotating body (106) and the sample receiving container (104) for transferring the rotating body (106) and the sample receiving container (104) between the measuring configuration and the rinsing configuration and to move the other of the rotating body (106) and the sample receiving container (104) stationary.

11. Measuring cell (100) according to one of claims 1 to 10, wherein in the measuring configuration between the rotating body (106) and the sample receiving container (104), the gap (110) is formed between a conical body (126) of the rotating body (106) and a conical receptacle (128) of the sample receiving container (104).

12. Measuring cell (100) according to one of claims 1 to 10, wherein in the measuring configuration between the rotating body (106) and the sample receiving container (104), the gap (110) is formed between a plate body (130) of the rotating body (106) and a plate receptacle (132) of the sample receiving container (104).

13. Measuring cell (100) according to one of claims 1 to 12, wherein a seal (134), in particular an O-ring, is arranged between the rotating body (106) and the sample receiving container (104).

14. Measuring cell (100) according to one of claims 1 to 13, wherein the control device (108) is designed to measure a plurality of samples to be measured sequentially in the measuring configuration in an automatically controlled manner and to rinse the sample receiving container (104) in an automatically controlled manner between at least some of the sequential measurements in the rinsing configuration.

15. Measuring cell (100) according to one of claims 1 to 14, wherein the control device (108) is designed to rinse the sample receiving container (104) sequentially by means of a plurality of rinsing fluids in the rinsing configuration.

16. Measuring cell (100) according to claim 15, wherein the sequential rinsing by means of a plurality of rinsing fluids is carried out by means of one or sequentially a plurality of rinsing liquids and sequentially at least one rinsing gas.

17. Rheometer (102) for rheologically measuring a sample, comprising a measuring cell (100) according to one of claims 1 to 16.

18. Rheometer (102) according to claim 17, comprising a drive device (136) for rotating the rotating body (106) in the measuring configuration and / or for raising or lowering the rotating body (106) relative to the sample receiving container (104) for transferring between the measuring configuration and the rinsing configuration.

19. Rheometer (102) according to claim 18, comprising a determining device (138) for determining rheological information with regard to the sample to be measured based on an analysis of a drive energy applied by the drive device (136) for rotatingly driving the rotating body (106) interacting with the sample to be measured.

20. Rheometer (102) according to one of claims 17 to 19, comprising a sensor device (140) for detecting sensor data indicative of rheological information with regard to the sample to be measured, in particular on an axis of rotation between the drive device (136) and the rotating body (106).

21. A method for operating a measuring cell (100) for a rheometer (102), the method comprising: Receiving a sample to be measured in a sample receiving container (104); Rotating a rotating body (106) which is at least partially arranged in the sample receiving container (104) to interact with the sample to be measured; Forming a gap (110) between the rotating body (106) and the sample receiving container (104) for contactless mutual arrangement of the rotating body (106) and the sample receiving container (104) for measuring the sample; and liquid-tight closing of the gap (110) between the rotating body (106) and the sample receiving container (104) for rinsing the sample receiving container (104).

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