EP3505258A1 - Laboratory centrifuge - Google Patents

Abstract

The invention relates to a laboratory centrifuge (1). The laboratory centrifuge has a centrifugation line (2) with a drive (3) and a rotor (4) driven by the drive (3). The centrifugation line (2) is supported against a housing (8) by at least one spring and / or damping device (7). The invention proposes that the laboratory centrifuge (1) has an inclination sensor which detects an orientation of a longitudinal and / or rotational axis (6) of the centrifugation line (2). The inclination sensor can be a gyroscope sensor which is held by a housing of the centrifugation line (2). It is also possible that the inclination sensor has a magnetic field sensor and a permanent magnet (31) that generates a magnetic field.

Description

TECHNICAL FIELD OF THE INVENTION

Laboratory centrifuges are used, for example, in biotechnology, the pharmaceutical industry, medical technology and environmental analysis. By means of a laboratory centrifuge, a centrifugation of a product, in particular a sample container with a sample or substance arranged therein, or a multiplicity of such products takes place. As a result of the centrifugation, accelerations acting on the product are to be generated so that a substance mixture formed by the sample or the substance is decomposed into components of different density. Depending on the chemical and / or physical properties of the substance mixture, a targeted control of the pressure and / or temperature conditions can additionally take place during the centrifugation. To mention just a few examples, the use of a laboratory centrifuge in connection with a polymerase chain reaction (PCR), a determination of the hematocrit, cytological examinations or the centrifuging of microtitres, blood bags, petroleum vessels or blood vessels u. Ä.

Laboratory centrifuges have a centrifugal column. In the Zentrifugationsstrang a rotor is driven by a drive. The products are held on the rotor, for which so-called fixed-angle, swing-out or drum rotors can be used (see www.sigmal-zentrifugen.de). The drive rotates the rotors with the high speed products to provide high accelerations (in particular, accelerations of more than 5,000 x g, more than 10,000 x g, or more than 20,000 x g) for centrifuging the products. For this purpose, for example, a drive of the rotor at a speed of more than 4,000 U / min, more than 5,000 U / min, more than 10,000 U / min, more than 15,000 U / min or even more than 20,000 U / min done.

A control or regulation and monitoring of the operation of the centrifugation train is carried out by controlling or monitoring the electrical impingement of the Drive. For example, a control or regulation of the drive speed and / or the drive torque of the drive can be carried out, whereby also predetermined courses for the drive speed or the drive torque can be traced. The centrifugation strand is supported via spring and / or damping devices with respect to a housing of the laboratory centrifuge. By means of a sensor, a deflection or acceleration of the centrifugation strand can be detected in order, for example, to be able to detect vibrations of the centrifugal strand with respect to the housing in the event of an imbalance of the rotor.

STATE OF THE ART

The publication DE 195 39 633 A1 describes it as known, depending on a deflection of a spring-mounted centrifugal strand to actuate a switching element, which is concluded that the presence of an imbalance. As problematic in DE 195 39 633 A1 considered in such, based on a deflection detection of imbalance that at a resulting possibly only at a higher speed unbalance, in particular by breaking a sample tube, the imbalance due to the high speed does not lead to the formation of a large deflection, which for the high speeds, a detection of imbalance on a via the deflection actuated switching element is not possible. The reason for this is said that the gyro precession starting from the rotor can both increase and decrease the extent of the deflection, so that premature or no detection of the imbalance takes place. Furthermore, the required high adjustment effort is criticized in the known, based on a deflection switching elements. Against this background beats DE 195 39 633 A1 that an acceleration of the centrifugation strand is detected by an electric acceleration sensor or a deflection of the centrifugation strand is determined via a displacement sensor. This should result in a simple calibration in the production, since under certain circumstances, a basic setting or calibration can be made only by a normal run and an imbalance run. The evaluation of the measurement signal preferably takes place by means of a bandpass filter whose center frequency corresponds to the rotational frequency of the rotor. If an unbalance of sufficient magnitude detected by the sensor, an alarm or a shutdown device is actuated. As a displacement sensor, the use of an optoelectronic sensor is proposed.

The publication DE 10 2011 100 044 B4 proposes to provide a carrier ring on a rotor. For the purpose of identifiable identification of different rotors are used in the Area of the carrier ring at different circumferentially distributed locations that are specific to the different rotors, magnets arranged. Adjacent to the carrier ring, magnetic sensors are arranged in a rotor chamber of the laboratory centrifuge, from whose measurement signals the number and circumferential angle of the magnets respectively arranged on a rotor can be determined and thus an identification of the rotor is possible. While the above-explained identification of the rotor takes place when the rotor is at rest, beats DE 10 2011 100 044 B4 Also, that the magnetic sensors can also be used in the operation of the laboratory centrifuge to detect an inclination of the axis of rotation of the rotor, which leads to a change in the distance between the magnet and the magnetic sensors, which is then deduced the presence of an imbalance.

The publication DE 10 2014 116 527 A1 discloses the use of a rotation angle sensor, a displacement sensor and three acceleration sensors, which are each responsible for a spatial direction. A detection of an imbalance at low speeds is to be done by means of the displacement sensor, while at higher speeds above 1,000 rev / min detection should be based on the measurement signal of an acceleration sensor. In addition, the centrifugation line can cooperate with an emergency switch, via which an emergency shutdown of the laboratory centrifuge is possible. The measurement signal of an acceleration sensor or of the displacement sensor is compared with characteristic curves stored in a control unit. If an amplitude of a measuring signal is greater than a limiting value dependent on a first characteristic curve, this signals an unbalance which does not present an immediate danger to the safety of the laboratory centrifuge or of the user. In this case, an audible or visual warning signal may be given to the user. If, on the other hand, an amplitude of the measuring signal exceeds a second limiting value, which is predetermined by a second stored characteristic curve, this is regarded as an indication of an immediate danger and an immediate need for action, with which an automatic emergency shutdown of the laboratory centrifuge can take place. The characteristics mentioned here can be speed-dependent. The control unit may have a data logger recording the measurement signals. The measurement signals recorded in this way can then be read out via the end of the operation of the laboratory centrifuge via a USB port and made available for maintenance, troubleshooting, product lifecycle management, etc. The three acceleration sensors responsible for the different spatial directions can be formed by a three-axis acceleration sensor, which can be mounted directly on an electronics board, which is fastened in the region of a lower engine mount of the drive near the drive shaft.

The publication DE 203 07 913 U1 discloses the storage of a rotor of a laboratory centrifuge via magnetic bearings. On the electrical operating variables of the magnetic bearing can be closed on the one hand to the size and location of an imbalance of the rotor. On the other hand, in the case of unbalance determined in this way, an active regulation of the bearing forces exerted by the magnetic bearings on the rotor can also take place in such a way that a compensation of the imbalance takes place.

DE 10 2015 102 476 A1 discloses the mounting of a drive shaft supporting a rotor of an electric motor in two engine mounts. An engine mount is supported via a bell-shaped housing, while the other engine mount is supported via a large inertial mass representing coupling body to spring elements. Adjacent to the two engine mounts, a measurement of the oscillating motion of the drive shaft takes place in each case via a displacement, velocity or acceleration sensor. The stator of the electric motor has windings which, depending on the measuring signals of the displacement, speed or acceleration sensors, are driven in such a way that they can counteract the vibrations of the drive shaft. From a difference of two path signals, which are measured by means of corresponding arranged in the engine bearings displacement sensors, a tilt of the drive shaft can be determined. In a bottom area facing the drive shaft, a speed sensor may be arranged, in which case a Hall sensor can be used, which detects a speed and a rotation angle and a rotational direction of the drive shaft.

OBJECT OF THE INVENTION

The present invention has for its object to propose a laboratory centrifuge with improved possibilities for monitoring and / or influencing the operating state of the laboratory centrifuge.

SOLUTION

The object of the invention is achieved with the features of the independent claim. Further preferred embodiments according to the invention can be found in the dependent claims.

DESCRIPTION OF THE INVENTION

• Ist ein Zentrifugationsstrang der Laborzentrifuge über Feder- und/oder Dämpfungseinrichtungen elastisch an einem Gehäuse der Laborzentrifuge abgestützt, führt sowohl eine Unwucht der rotierenden Komponenten des Zentrifugationsstrangs als auch eine nicht koaxiale Ausrichtung einer Längs- oder Rotationsachse des Zentrifugationsstrangs zu der Erdbeschleunigung oder dem Schwerefeld der Erde zu einer statischen und/oder dynamischen Auslenkung des Zentrifugationsstrangs gegenüber dem Gehäuse der Laborzentrifuge. Dies kann im Folgenden anhand Extremüberlegungen zu der Federsteifigkeit und Dämpfung der Feder- und/oder Dämpfungseinrichtungen wie folgt beispielhaft erläutert werden:
  • Ist die Längs- und/oder Rotationsachse des Zentrifugationsstrangs nicht parallel zur Erdbeschleunigung ausgerichtet, so ist unter Umständen der Schwerpunkt des Zentrifugationsstrangs exzentrisch zu den Feder- und/oder Dämpfungseinrichtungen angeordnet, woraus ein erstes Kippmoment resultiert, welches bestrebt ist, die Abweichung der Ausrichtung der Längs- und/oder Rotationsachse des Zentrifugationsstrangs gegenüber der Erdbeschleunigung zu vergrößern. Dieses erste Kippmoment wirkt grundsätzlich sowohl bei Stillstand des Zentrifugationsstrangs als auch bei einer Rotationsbewegung der rotierenden Komponenten des Zentrifugationsstrangs und ist unabhängig davon, ob die rotierenden Komponenten des Zentrifugationsstrangs eine Unwucht aufweisen. Grundsätzlich ändert sich die Orientierung des ersten Kippmoments mit einer Drehbewegung der rotierenden Komponenten des Zentrifugationsstrangs nicht und der Betrag des ersten Kippmoments ist auch von einer Drehzahl der rotierenden Komponenten des Zentrifugationsstrangs unabhängig. Andererseits ergibt sich (auch bei einer parallelen Ausrichtung der Längs- und/oder Rotationsachse des Zentrifugationsstrangs) ein zweites Kippmoment infolge einer etwaigen Unwucht der rotierenden Komponenten des Zentrifugationsstrangs. Dieses zweite Kippmoment ist im Stillstand der rotierenden Komponenten klein und ergibt sich aus dem Produkt des Unwuchtradius (also des Abstands der Unwucht von der Rotationsachse) und der Unwuchtmasse. Das zweite Kippmoment steigt aber stark mit der Erhöhung der Drehzahl an.

The present invention is based in particular on the following findings:

• If a centrifuge strand of the laboratory centrifuge is elastically supported on a housing of the laboratory centrifuge via spring and / or damping devices, both an unbalance of the rotating components of the centrifugation strand and a non-coaxial alignment of a longitudinal or rotational axis of the centrifugation strand lead to the gravitational acceleration or gravitational field of the earth to a static and / or dynamic deflection of the centrifugal column relative to the housing of the laboratory centrifuge. This can be explained below by way of example based on extreme considerations of the spring stiffness and damping of the spring and / or damping devices as follows:
  • If the longitudinal and / or rotational axis of the centrifugation strand is not aligned parallel to the gravitational acceleration, then the center of gravity of the centrifugation strand may be arranged eccentrically to the spring and / or damping devices, resulting in a first tilting moment, which tends to the deviation of the orientation of the Longitudinal and / or rotational axis of the centrifugal strand to increase the gravitational acceleration. This first tilting moment basically acts both when the centrifugation strand is at a standstill and during a rotational movement of the rotating components of the centrifuging strand and is independent of whether the rotating components of the centrifugation strand have an imbalance. In principle, the orientation of the first tilting moment does not change with a rotational movement of the rotating components of the centrifuging strand and the magnitude of the first tilting moment is independent of a rotational speed of the rotating components of the centrifugal strand. On the other hand, there is also a second tilting moment (also in the case of a parallel orientation of the longitudinal and / or rotational axis of the centrifuging strand) due to any imbalance of the rotating components of the centrifuging strand. This second tilting moment is small at standstill of the rotating components and results from the product of the unbalance radius (ie the distance of the imbalance from the axis of rotation) and the imbalance mass. The second overturning moment but increases sharply with the increase in speed.

In addition, the conditions of motion, force and torque on the centrifugation strand are strongly dependent on the dimensioning of the spring and / or damping devices, by means of which the centrifugation strand is supported on the housing of the laboratory centrifuge.

This can be simplified for extreme designs of the spring and / or damping devices are explained: For a negligible spring and / or damping device of the centrifugal strand is gimballed for a simplified view, so that the longitudinal and / or rotational axis of the centrifugal strand automatically parallel to the acceleration of gravity can align. On the other hand, an infinitely high rigidity and damping of the spring and / or damping devices ensures that the orientation of the longitudinal and / or rotational axis of the centrifugation strand is maintained in accordance with the alignment of the laboratory centrifuge with respect to the environment (so that the deviation of the longitudinal and / or rotational axis from that Acceleration depends exactly on how "horizontally" the housing of the laboratory centrifuge and thus the centrifuge line are set up).

• Tatsächlich bilden die rotierenden Komponenten des Zentrifugationsstrangs einen Kreisel, wobei die Feder- und/oder Dämpfungseinrichtungen Randbedingungen des Kreisels vorgeben. Für den Extremfall der verschwindenden Steifigkeit und Dämpfung der Feder- und/oder Dämpfungseinrichtungen bildet der Zentrifugationsstrang einen freien Kreisel, während für endliche Werte der Steifigkeit und Dämpfung der Feder- und/oder Dämpfungseinrichtungen der Zentrifugationsstrang einen gefesselten Kreisel bildet. Die Dynamik des Kreisels ist komplex und wird durch die Eulerschen Kreiselgleichungen beschrieben. Hierbei beeinflusst die Dynamik der Ausrichtung der Längs- und/oder Rotationsachse des Zentrifugationsstrangs ein Deviationsmoment (Maß für das Bestreben des Kreisels seine Rotationsachse zu verändern, wenn der Kreisel nicht um eine seine Hauptträgheitsachsen rotiert) und ein Kreiselmoment. Der Zentrifugationsstrang kann komplexe Nutationsbewegungen und Präzessionsbewegungen ausführen, wobei die Bewegung der Rotationsachse des Zentrifugationsstrangs auf einem Nutationskegel und/oder Gangpolkegel erfolgen kann.

After all, the above consideration of the two tilting moments is only a great simplification, which takes into account the actual complex conditions only in a rough approximation:

• In fact, the rotating components of the centrifugal strand form a gyro, with the spring and / or damping devices prescribing boundary conditions of the gyroscope. For the extreme case of vanishing stiffness and damping of the spring and / or damping devices of the centrifugal strand forms a free gyroscope, while for finite levels of stiffness and damping of the spring and / or damping devices of the centrifugal strand forms a tethered gyroscope. The dynamics of the gyro is complex and is described by the Eulerian gyroscopic equations. In this case, the dynamics of the orientation of the longitudinal and / or rotational axis of the centrifugal strand influences a deviation moment (measure for the tendency of the gyroscope to change its axis of rotation if the gyroscope does not rotate about one of its principal axes of inertia) and a gyroscopic moment. The centrifugation strand can perform complex nutation movements and precession movements, whereby the movement of the axis of rotation of the centrifugation strand can take place on a nutation cone and / or gangue cone.

These complex processes are not taken into account by the sensors and evaluation methods known from the prior art. Rather, regardless of the cause of the deviation of the rotational movement of the rotor from a stationary axis of rotation (that is, regardless of whether the laboratory centrifuge is not exactly horizontal or an imbalance of the rotating components of the centrifugal column is present) takes place according to the prior art a comparison of a measured deflection or the acceleration of the centrifugation strand with a priori predetermined threshold values.

According to the invention, for the first time an inclination sensor is used in a laboratory centrifuge which detects an alignment of a longitudinal and / or rotational axis of the centrifugation strand. The inclination sensor thus generates a measurement signal in which a change is directly correlated or proportional to a change in the orientation of the longitudinal and / or rotational axis of the centrifugation strand. On this basis, for the first time a measurement signal for the alignment of the longitudinal and / or rotational axis of the centrifugation strand, which provides alternative or supplementary evaluation options for static and / or dynamic changes in the position and / or orientation of the centrifugation strand, which in particular alternative or additional and improved Possibilities for identifying an insufficient alignment of the longitudinal and / or rotational axis to the acceleration due to gravity and / or an existing imbalance of the rotating components of the centrifugal strand are provided. To mention only an example which does not limit the invention, the evaluation can also take into account the aforementioned gyro effects on the basis of the measuring signal of the inclination sensor.

In principle, an inclination sensor based on an arbitrary measuring principle can be used for the inclination sensor within the scope of the invention. For an embodiment according to the invention, the inclination sensor is a gyroscope sensor. In this case, the gyroscope sensor is held by a housing of the centrifugation strand, so that the gyroscope sensor does not rotate with the rotating components of the centrifugation strand, but can detect an inclination and thus a change in inclination of the longitudinal and / or rotational axis of the centrifugation strand. A gyroscope, which may also be referred to as a gyrostabilizer or gyro instrument, includes a rotating symmetric gyro which is journaled relative to a suspension such that upon pivoting of the suspension due to pivoting of the gyroscope relative to the gyro suspension, its axis of rotation does not change. The suspension may, for example, be a gimbal suspension. A pivoting of the suspension relative to the measuring gyroscope is converted into a measuring signal in the case of a gyroscope sensor. In an inventive use of the gyroscopic sensor, the suspension is attached to a non-rotating housing of the centrifugation strand, in particular the drive of the centrifugation strand. More modern embodiments of gyroscope sensors, which may also have no rotating measuring gyroscope, and can also be used within the scope of the invention, find today in smartphones, tablets and game consoles, for example, use.

For a further embodiment of the laboratory centrifuge according to the invention, the inclination sensor is designed as a magnetic field sensor, by means of which a strength and / or orientation of a magnetic field is detected and converted into a measurement signal. Furthermore, the inclination sensor has a permanent magnet. The permanent magnet generates a magnetic field whose strength and / or orientation is detected by the magnetic field sensor. It is possible, for example, that the magnetic field sensor is held by a housing of the centrifugation strand, while the permanent magnet adjacent to the magnetic field sensor is held on a housing of the laboratory centrifuge. Alternatively, it is possible that the permanent magnet is attached to the housing of the centrifugation strand, while the magnetic field sensor is held on the housing of the laboratory centrifuge. If it then comes to a change in the inclination of the centrifugation strand relative to the housing of the laboratory centrifuge, this leads to a relative movement between the magnetic field sensor and permanent magnets, which has an increase in the distance of the magnetic field sensor from the permanent magnet result and / or a change in orientation of the magnetic field generated by the permanent magnet relative to the magnetic field sensor result. Thus, in this embodiment, based on the strength of the magnetic field and / or the direction of the magnetic field detected by the magnetic field sensor, it is possible to deduce the inclination of the centrifugal strand relative to the housing.

If the magnetic field sensor for a possible embodiment is based on the detection of a magnetic flux density (so-called magnetometer), then any sensor types (in particular Hall sensors, Förster probes) or saturation core magnetometers or fluxgate sensors, SMR sensors, thin-film sensors that change their resistance under the influence of magnetic flux, field plates u. Ä. Be used.

For a particular embodiment of the invention, two inclination sensors are present in the laboratory centrifuge. In this case, a tilt sensor may be formed as a gyroscope sensor, which is held on a housing of the centrifugation strand. On the other hand, the other inclination sensor is formed with a permanent magnet and a magnetic field sensor interacting with the magnetic field of the permanent magnet. The two inclination sensors can be used redundantly. It is also possible that the two on having a different measuring principle based tilt sensors different sensitivities and / or frequency ranges for the recording of a measurement signal.

Within the scope of the invention, at least one acceleration sensor may be present (in addition to the at least one inclination sensor).

The signal processing of a measurement signal of an acceleration sensor usually has only a limited resolution. For example, a harmonic oscillation of the centrifugation strand with the frequency of the drive movement of the rotor results in an acceleration of the centrifugation strand which is proportional to the deflection of the oscillation of the centrifugation strand and the square of the frequency of this oscillation (which usually corresponds to the rotational speed of the rotor or subsystem). and / or superharmonic corresponds to this speed) is. Thus, the acceleration amplitude measured by an acceleration sensor increases with an increase in frequency, i. H. with an increase in the drive speed of the rotor, strong. On the other hand, the acceleration amplitude measured by an acceleration sensor is also dependent on a possible resonance function or transfer function of the vibration system, which is formed with the centrifugation strand and its support via the at least one spring and / or damping device. A sensitivity of the acceleration sensor must be adjusted or optimized according to the prior art for all occurring frequencies and amplitudes. This, in conjunction with the limited resolution of the digital processing of the measurement signal of the speed sensor acceleration sensor of the rotor with small occurring accelerations, can lead to a poor resolution of the measurement signal and a poor signal-to-noise ratio. In addition, known acceleration sensors and / or signal processing used for the evaluation of the measurement signal of the acceleration signal can also have only limited frequency ranges in which they can generate an acceleration signal with sufficient accuracy.

For an embodiment according to the invention, it is proposed that the centrifugation strand not only have a sensor type of an acceleration sensor, with which the acceleration of the centrifugation strand is detected in one or more spatial directions with predetermined sensitivity in the predetermined frequency range of this sensor type. Rather, the centrifugation strand has at least two acceleration sensors, which measure an acceleration of the drive with different sensitivities and / or in different frequency ranges, wherein preferably the two acceleration sensors measure the acceleration in the same spatial direction. According to the invention, two sensors of different sensor types are thus used, with which the acceleration of the drive in the same spatial direction is measured in different frequency ranges and / or with different sensitivities. This embodiment of the invention is based on the finding that when using a single sensor type of acceleration sensor with predetermined sensitivity and frequency range selection of this sensor type must be such that the sensitivity and the frequency range of the sensor type are chosen so that the acceleration sensor as possible in all relevant Operating situation provides sufficiently good measurement signals to make the required evaluation can. For example, the acceleration sensor must deliver sufficiently good measurement signals both at low speeds (and possibly large deflections of the centrifugal column) and at high speeds (and possibly small deflections of the centrifugation train), which is only possible to a limited extent. On the other hand, the sensors used according to the invention of different sensor types with different sensitivities and / or different frequency ranges can each be adapted to different operating states (or a respectively assigned operating state region) of the laboratory centrifuge. Thus, for example, an acceleration sensor may be designed such that it has a measurement signal (in particular with a measurement error of less than 10%, less than 5% or less than 3%) both for a frequency 0 (ie a DC component) and for low frequencies (eg for frequencies from 0 to 50 hertz, 0 to 100 hertz, 0 to 200 hertz or 0 to 500 hertz), while another accelerometer then generates a measurement signal (in particular with a measurement error of less than 10%, less than 5%). or less than 3%) in a frequency range which is at least partially above the frequency range of the former sensor and, for example, in a frequency range above 50 hertz, 100 hertz, 150 hertz or 200 hertz or 500 hertz.

If, for example, the first acceleration sensor detects acceleration in a low frequency range, monitoring can already take place with the start of the laboratory centrifuge by means of the first acceleration sensor, if a longitudinal and / or rotational axis of the centrifugation strand is aligned parallel to the acceleration vector and / or the rotating components of the centrifugal force Zentrifugationsstrangs have an imbalance. On the other hand, the second acceleration sensor can be responsible, even for higher or higher Rotation speeds to monitor the acceleration. Under certain circumstances, then can be detected by means of the second acceleration sensor with a relatively high sensitivity when for larger or maximum rotational speeds a product fails (eg., A sample tube breaks), which results without initial imbalance of the rotor until the operation of the laboratory centrifuge an imbalance, then can only be effective for a short time or permanently. In some circumstances, an evaluation may also be advantageous in such a way that both the measurement signal of at least one inclination sensor and the measurement signal of at least one acceleration sensor are evaluated. If, for example, it is detected by means of the inclination sensor that the longitudinal and / or rotational axis of the centrifugation strand is inclined and if the acceleration sensor generates a harmonically oscillating measuring signal in a spatial direction, for example, it can be concluded with a safety that is higher than that of the prior art that a Imbalance is present, which on the one hand leads to the tilt detected by the inclination sensor and on the other hand leads to the oscillating measurement signal of the acceleration sensor as a result of circulating the imbalance about the longitudinal and / or rotational axis of the centrifugal strand.

For an alternative or cumulative solution encompassed by the invention, the centrifugation strand has a sensor which is based on a sensor principle which has hitherto not been used for a laboratory centrifuge. For this embodiment, a sensor is used which determines the alignment of the drive with respect to a magnetic field Earth measures. For this purpose, for example, a Hall sensor can be used. On the basis of a measurement signal thus determined, which relates to the orientation of the drive relative to the magnetic field of the earth, it can be detected on the one hand whether the laboratory centrifuge has been set up correctly (i.e., horizontally), which is possible even when the rotor is at a standstill in view of the sensor principle used. On the other hand, can also be detected during operation of the laboratory centrifuge tilting of the centrifugal strand due to the swinging support of the same via the spring and / or damping devices relative to the housing and / or as a result of a static rotation without rotation of the rotor imbalance or dynamic unbalance excitation upon rotation of the rotor be and u. U. the extent of tilt, a size of the imbalance and / or a position of the imbalance can be determined.

In a further embodiment of the invention (preferably in addition to the aforementioned sensors) at least one sensor is present, which detects a rotation angle, an angular velocity or an angular acceleration of a drive shaft of the drive.

Furthermore, a temperature sensor may be present. It is advantageous if this temperature sensor is arranged closely adjacent (for example, less than 10 cm, less than 5 cm or less than 3 cm adjacent) of the other sensors. This temperature sensor then preferably measures not the temperature in the rotor chamber or the temperature inside the drive, but the temperature to which the sensors are exposed.

Finally, alternatively or cumulatively, it is possible for a 9-axis sensor to be present.

On all of the aforementioned sensors, ie in particular the inclination sensors, the gyroscope sensor, the magnetic field sensor, the permanent magnet, the acceleration sensors, the sensor for detecting the orientation of the drive against a magnetic field of the earth, the sensor for detecting a rotation angle, an angular velocity or an angular acceleration of a drive shaft of the drive, the temperature sensor and / or the 9-axis sensor will be referred to in the following with the common generic term "sensor".

It is possible that at least one of said sensors is arranged at any point of the housing of the drive or on a rigidly coupled thereto component. For a particular proposal of the invention, the sensors are arranged on a sensor board with which they (possibly with other electrical and electronic components) form a structural unit. The sensor board can then be connected via a plug, at least one conductor, a bus system and / or an electrical power supply with decentralized arranged from the sensor board electronic control units, storage, output devices, data loggers and / or power supplies.

In principle, the sensor board can be arranged at any point on the centrifugation strand or the housing of the drive. However, this is preferably located on the side facing away from the rotor of the centrifugation strand, in particular the housing of the drive. On the one hand, this has the advantage that the sensor board, for example, does not have to extend in the region of a rotor chamber, with the result that the space required here is reduced. On the other hand, for the arrangement of the sensor board on the side facing away from the rotor of the drive may also be avoided that with the operation of the laboratory centrifuge resulting in the rotor chamber during operation due to the high speed of the rotor temperature increase not on the temperature of the circumstances sensitive electrical and electronic components on the sensor board. So may also be a Temperature influence on the accuracy of the measurement signals of the sensors of the sensor board are at least reduced.

In the event that, as explained above, the sensor board is arranged on the side facing away from the rotor of the drive, the sensor for detecting the movement of the drive shaft is preferably also arranged on this sensor board. It is possible that then this sensor is arranged on the sensor board immediately adjacent to an end portion of the drive shaft of the drive to detect the movement of the drive shaft. It is even possible that the drive shaft or an end-side pin-shaped projection which rotates with the drive shaft, or an incremental encoder of the drive shaft protrudes through a recess of the sensor board, while the sensor can then surround the incremental encoder or the end portion of the drive shaft or the extension.

In a further embodiment of the invention, an electronic control unit is present in the laboratory centrifuge, which processes the measurement signal of at least one of the aforementioned sensors. Preferably, the electronic control unit is also arranged on the sensor board.

The electronic control unit can have any desired control logic required for operation and evaluation of the sensors. Thus, for example, a calibration factor, a calibration curve or a calibration field for at least one sensor can be present in the control unit or an associated memory unit, by means of which a conversion of the electrical measurement signal provided by the sensor takes place. An evaluation of the thus converted signal can then also by the control unit, by another control unit of the laboratory centrifuge or even by an outside of the laboratory centrifuge arranged control unit, to which the signal is transmitted by wire or wireless, take place.

For an embodiment according to the invention, the control logic determines whether the laboratory centrifuge is set up so that the drive axis of the drive or a main axis of inertia of the rotating components of the centrifugation strand is aligned in the direction of the acceleration due to gravity. This can be done, for example, based on the detection of a Deviationsmomentes by the tilt sensors used or by otherwise evaluation of at least one tilt sensor and / or another sensor.

Alternatively or additionally, it is possible that by means of the control logic an imbalance of the rotating components of the centrifugation strand is determined. It is possible here that only a comparison of a measured value takes place with a threshold value, which then concludes that the drive axis of the drive or a main axis of inertia of the rotating components of the centrifugal strand is not aligned in the direction of gravity acceleration vector or an imbalance of the rotating components of the centrifugal strand is great.

It is also possible that an evaluation is made such that the extent of the deviation of the orientation of the drive axis of the drive or the main axis of inertia and / or the size of an imbalance of the rotating component of the centrifugal strand or its angular position is determined with respect to the rotation about the axis of rotation.

For a particular embodiment of the invention, the control logic is able to differentiate based on the measurement signals determined by the sensors, if the laboratory centrifuge is positioned so that the drive axis of the drive or a main axis of inertia of the rotating component of the centrifugal strand is not aligned in the direction of the gravitational acceleration vector or an imbalance of the rotating components of the centrifugation strand is present. In order to name only an example which does not limit the invention, on the basis of this distinction the user of the laboratory centrifuge (possibly already before the operation of the laboratory centrifuge, after a termination of the centrifugation or after the proper completion of the centrifugation) can be given a feedback that either the propulsion drive axle or main inertia axle is misaligned so that the laboratory centrifuge placement on the pad must be checked or there is imbalance in the rotating component of the centrifugation string, indicating improper placement of the laboratory centrifuge rotor with the products or may indicate a defect of a rotating component of the centrifugation strand.

For a further proposal of the invention, an error criterion is determined by the control logic of the control unit. For example, the error criterion may be present if a measured acceleration or slope is above a threshold or a characteristic dependent on the speed of the rotor or if it is detected that the rotor is not rotationally symmetric or unbalanced or if the laboratory centrifuge is not properly aligned with the acceleration due to gravity is. If such an error criterion exists, generates the control logic of the control unit an error message, which may be an optical error message, an acoustic error message or even an error entry in a fault memory, to name just a few non-limiting examples. But it is also possible that in the presence of such an error criterion the operation of the laboratory centrifuge is interrupted, if this has already been started, or this operation is changed, which can be done, for example, by reducing the speed of the rotor or a deceleration according to a predetermined braking curve. But it is also possible that in the presence of the error criterion recording of the operation of the laboratory centrifuge, so a start of the drive of the rotor is prevented.

If it is determined in the context of the invention that the rotating components of the centrifuging strand have an imbalance, the control logic of the electronic control unit can be used to automatically control or regulate a position of a compensating mass to compensate for the imbalance. For example, depending on the detected position and / or size of an imbalance, the radius of rotation or the circumferential angle of a balancing mass rotating with the rotor can be changed via an actuator. It is also possible that by the control logic of the electronic control unit a bearing, a compensation device, via which forces can be exerted on the centrifugation strand by means of an actuator, and / or at least one spring and / or damping device is controlled or regulated so that a Impact of an imbalance and / or an effect of improper alignment of the drive axle of the drive to the acceleration due to gravity is at least reduced. To mention only a non-limiting example, by means of the control logic, a regulation of the spring stiffness and / or damping of the spring and / or damping device can be carried out. It is also possible that in the bearing, which can then be designed as an electromagnetic bearing, or in the compensation device, a compensating force is generated, which counteracts the resulting vibration of the centrifugation strand.

The invention further proposes that in the control unit control logic is present, which detects a failure of at least one product and a resulting imbalance of the rotor. Thus, in the context of the invention, the detection of an imbalance resulting only during operation of the laboratory centrifuge is possible. For example, the control logic evaluates the signal of an acceleration sensor or tilt sensor at very high rotational speeds of the laboratory centrifuge in order to be able to detect by means of an increase in the detected measurement signal, at the high speeds and high associated centripetal accelerations acting on the product, failure of the product, particularly breakage of the sample tube, occurs. This may, for example, be detected by means of an abruptly changing amplitude of the measurement signal detected by the sensor as a result of the sudden failure of the product. While in principle the product has a relatively small mass compared to the rotating mass of the centrifugation strand and the vibration of the centrifugation strand only slightly changes due to the failure of the product in the steady state, in the immediate time environment of the failure of the product, a transient transient or transient Transient behavior result, which can be detected by means of the sensor, in particular the inclination sensor and / or the acceleration sensor, within the scope of the invention.

In a further embodiment of the laboratory centrifuge according to the invention, a temperature measured by a temperature sensor is used to carry out a temperature compensation of a measuring signal of at least one other sensor, preferably all of the sensors mentioned here. If the sensors, including the temperature sensor, are arranged on a sensor board, the temperature sensor detects a temperature representative of the further sensors arranged on the sensor board. If a temperature response is known for the other sensors and this is stored, for example, in a memory unit of the control unit, a temperature compensation can be carried out in a simple manner in the control unit via the temperature measured by the temperature sensor. In this way, the accuracy of the measuring signals of the sensors can be increased.

For an embodiment according to the invention, the measurement signal of a temperature sensor is not or not exclusively used for a temperature compensation of the measurement signals of the sensors. Rather, the temperature measured by the temperature sensor is taken into account in a determination and / or evaluation of a magnitude of an imbalance of the rotating components of the centrifugation strand. Alternatively or additionally, it is possible for the temperature to be taken into account in a determination and / or evaluation of a non-parallel alignment of the longitudinal and / or rotational axis of the centrifugal strand or of a principal axis of inertia of the rotating components of the centrifugal strand for gravitational acceleration. This will be explained with reference to the following non-limiting example: The centrifugal strand forms as a result of its support via the spring and / or damping device as previously explained a vibration system whose vibration behavior due to a Excitation by an imbalance of the rotating components of the centrifugation strand and / or due to a non-parallel alignment of the longitudinal and / or rotational axis of the centrifugal strand to the acceleration due to gravity acceleration depends on a resonance function or transfer function of the oscillatory system. However, this resonance or transfer function is in turn dependent on the stiffness and damping of the spring and / or damping devices. If the stiffness and / or damping of the spring and / or damping device changes as a result of a temperature change in the region of the spring and / or damping device, this leads to a change in the resonance function or transfer function. This means that for different temperatures the same imbalance or the same deviation of the orientation of the longitudinal and / or rotational axis of the centrifugal strand from the acceleration sensor can lead to different deflections, speeds or accelerations and inclinations. Conversely, to allow conclusions about the orientation of the longitudinal and / or rotational axis of the centrifugation strand or imbalance from the measurement signals of the sensors, a consideration of the temperature dependence of the resonance function or transfer function and thus the stiffness and damping is required. Such a consideration can be done by modeling the temperature dependence of the resonance function or transfer function and thus converting the measurement signal depending on the applicable at the present temperature resonance function or transfer function. In the simplest case, however, such a consideration can already take place in that a comparison of the measurement signal with a threshold value takes place, in which case the threshold value can be dependent on the temperature. In this case, any dependence is possible, for example, a step-dependent dependence of the threshold value for individual temperature ranges, a dependency corresponding to a straight line or an arbitrarily shaped smooth, bent or jumped curve or a functional dependency or a dependency on a characteristic field which determines the dependence on further Operating parameters can take into account. It is possible, for example, that another operating parameter in such a map is a type of rotor used and / or different types of assembly of the rotor, wherein the detection of the type or the assembly can be done automatically or is entered via an input of a user to the laboratory centrifuge.

In a further embodiment of the invention, the control logic on the basis of measured by the sensors measurement signals and / or error criteria before an adjustment of a lifetime and / or a service interval of the laboratory centrifuge, the drive or the rotor before. This Design is based on the finding that when operating the laboratory centrifuge with suboptimal operating conditions, for example. With a force on the bearings and the mechanical components of the laboratory centrifuge performing rotating imbalance, a load on the components of the laboratory centrifuge increases, thus reducing the life and / or a service interval is required to ensure reliable operation of the laboratory centrifuge.

• ein Teil des Rotors oder
• ein Arm oder ein Halter, an dem ein Probenbehälter oder mehrere Probenbehälter gehalten ist/sind,

versagt, woraus sich ein Unwucht ergeben kann.An imbalance of the rotating components of the centrifugal strand can already result before the start of the rotation of the rotor, if the products are not evenly distributed over the circumference, which may be the case, for example, if at least partially wrong products are connected to the rotor or individual Products are missing. It is also possible that the rotor itself (without the products) or another rotating component of the centrifugation strand, for example due to damage during a previous centrifugation or during assembly, has an imbalance. But it may also be a non-rotationally symmetrical placement of the rotor with the products or and thus an imbalance result in the operation of the laboratory centrifuge with a recording of the centrifugation. This may be the case, for example, if there is inhomogeneous centrifugation in the samples placed in the products, or if there is a failure of the product, in particular a sample tube or other sample container. It is also possible that during operation of the laboratory centrifuge

• a part of the rotor or
• an arm or a holder holding a sample container or a plurality of sample containers,

fails, which can result in an imbalance.

In the context of the invention, a determination as to whether the rotor is not rotationally symmetrically equipped with the products, for example. By evaluation of a measurement signal of an acceleration sensor, as results in non-rotationally symmetrical assembly of the rotor with the products an imbalance, which then to a (u U. circumferential with the rotation in the circumferential direction) acceleration and vibration of the Zentrifugationsstrangs leads, which can be measured by means of the acceleration sensor. It is possible in this case that a measured acceleration is compared with a threshold value or with one of the Speed of the rotor-dependent characteristic curve, it being concluded when the characteristic curve or the threshold value is exceeded that the rotor is not rotationally symmetrically equipped with the products and / or has an imbalance. However, it is also possible that this is determined on the basis of a detection of a swinging change in inclination of the centrifugation strand, which can be detected by means of the inclination sensor used according to the invention.

For a further embodiment of the invention, the electronic control unit is equipped with control logic which detects an angular position and / or a size of an imbalance. For very small rotational speeds of the rotor far below the resonant frequency of the vibration system formed with the centrifugal strand and the spring and / or damping devices corresponds to the angular position of the circumferential deflection of the centrifugation strand approximately the angular position of the imbalance, with the result that the acceleration, then by an acceleration sensor held on the drive has a minimum. For realistic rotational speeds of the rotor results between the deflection (and thus the acceleration) and the position of the unbalance a phase shift, which starts at 0 ° for the frequency 0, in the resonant frequency is 90 ° and is 180 ° for high speeds. To identify the angular position of the imbalance, this phase shift can be stored in the control unit and an associated memory unit as a characteristic. This characteristic curve is then taken into account for detecting the angular position of the imbalance. In this case, the characteristic curve can also be dependent on the measured temperature.

If the laboratory centrifuge is tilted and there is an angle between the longitudinal and / or rotational axis of the centrifugation string and the acceleration due to gravity, the rotor (and thus the products) experiences an oscillating acceleration in the direction of the gravitational acceleration vector, which is undesirable because of this oscillating acceleration interfere with the centrifugation and the desired segregation of the sample.

To name just a non-limiting example, with an acceleration sensor (for example, for a low drive speed of the rotor), the acceleration of the centrifugation strand can be measured. If there is no or only a slight acceleration of the acceleration sensor, neither a rotationally symmetrical placement or imbalance of the rotor nor a deviation of the orientation of the longitudinal and / or rotational axis of the centrifugal strand with respect to the orientation of the acceleration due to gravity is present. Measures, however the acceleration sensor a constant DC component of the acceleration, this correlates with a constant, independent of the rotation of the rotor oblique position of the longitudinal and / or rotational axis of the Zentrifugationsstrangs, so that the DC component of the acceleration signal with the angle between the orientation of the longitudinal and / or rotational axis the centrifugation strand and the orientation of the gravitational acceleration correlated via a dependency, which, for example, can be stored in a map. On the other hand, if an acceleration which oscillates in accordance with the rotational speed of the rotor is correlated, the amplitude of this oscillating acceleration correlates with the imbalance. It is possible that the magnitude of the unbalance is deduced from the amplitude of the oscillating acceleration via the (possibly temperature-dependent) resonance curve or transfer function of the vibration system. However, it is also possible that different sensors are used to distinguish between an imbalance of the centrifugation strand and the deviation of the orientation of the longitudinal and / or rotational axis of the centrifugal strand from the orientation of the gravitational acceleration.

Advantageous developments of the invention will become apparent from the claims, the description and the drawings. The advantages of features and of combinations of several features mentioned in the description are merely exemplary and can take effect alternatively or cumulatively, without the advantages having to be achieved by embodiments according to the invention. Without thereby altering the subject matter of the appended claims, as regards the disclosure of the original application documents and the patent, further features can be found in the drawings, in particular the illustrated geometries and the relative dimensions of several components and their relative arrangement and operative connection. The combination of features of different embodiments of the invention or of features of different claims is also possible deviating from the chosen relationships of the claims and is hereby stimulated. This also applies to those features which are shown in separate drawings or are mentioned in their description. These features can also be combined with features of different claims. Likewise, in the claims listed features for further embodiments of the invention can be omitted.

The features mentioned in the claims and the description are to be understood in terms of their number, that is exactly this number or a larger number than said Number exists without requiring an explicit use of the adverb "at least". If, for example, a tilt sensor is mentioned, it should be understood that exactly one tilt sensor, two tilt sensors or more tilt sensors are present. These features may be supplemented by other features or be the only characteristics that make up the product in question.

The reference numerals contained in the claims do not limit the scope of the objects protected by the claims. They are for the sole purpose of making the claims easier to understand.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1

zeigt in einer horizontalen Ansicht Komponenten einer Laborzentrifuge, nämlich einen Zentrifugationsstrang, der über Feder- und/oder Dämpfungseinrichtungen gegenüber einem Gehäuse abgestützt ist, wobei der Antrieb des Zentrifugationsstrangs eine mit mehreren Sensoren ausgestattete Sensorplatine aufweist.

Fig. 2

zeigt die Sensorplatine in einem Aufnahmering in einer räumlichen Ansicht schräg von oben.

Fig. 3

zeigt stark schematisiert die Anordnung von Sensoren und einer elektronischen Steuereinheit auf einer Sensorplatine.

In the following the invention will be further explained and described with reference to preferred embodiments shown in the figures.

Fig. 1

shows in a horizontal view components of a laboratory centrifuge, namely a centrifugal strand, which is supported by means of spring and / or damping devices relative to a housing, wherein the drive of the centrifugation strand has a multi-sensor equipped sensor board.

Fig. 2

shows the sensor board in a receiving ring in a spatial view obliquely from above.

Fig. 3

shows very schematically the arrangement of sensors and an electronic control unit on a sensor board.

DESCRIPTION OF THE FIGURES

Fig. 1 shows in a horizontal view components of a laboratory centrifuge 1. A centrifugal strand 2 has an electric drive 3, a rotor 4 and a drive and / or rotor shaft 5, via which the drive 3, the rotor 4 in rotation about a longitudinal and / or rotational axis 6 can put on.

1. a) Einfederungen und Schwingungen in Richtung der Längs- und/oder Rotationsachse 6,
2. b) Auslenkungen des Zentrifugationsstrangs 2 quer zur Längs- und/oder Rotationsachse 6 und
3. c) Neigung der Längs- und/oder Rotationsachse 6 um einen Winkel gegenüber dem Gehäuse 8 oder gegenüber einem Erdbeschleunigungsvektor 16.

The centrifugation strand 2 is resiliently and dampably supported on a housing 8 of the laboratory centrifuge 1 via spring and / or damping devices 7a, 7b. The centrifugation train 2 and the spring and / or damping devices 7 form a vibration system 9. In the vibration system 9, the centrifugal strand 2 forms the oscillating mass, while the stiffness and the damping of the vibration system 9 are predetermined by the spring and / or damping devices 7. The spring and / or damping devices 7a, 7b preferably allow deflections and thus possibly oscillating degrees of freedom of the vibration system 9 as follows:

1. a) deflections and vibrations in the direction of the longitudinal and / or rotational axis 6,
2. b) deflections of the centrifugal strand 2 transversely to the longitudinal and / or rotational axis 6 and
3. c) inclination of the longitudinal and / or rotational axis 6 at an angle relative to the housing 8 or with respect to a gravitational acceleration vector 16.

The spring and / or damping devices 7a, 7b are arranged in the region of the bottom of the laboratory centrifuge 1 and possibly arranged in a space of the laboratory centrifuge 1, which is completely or largely or partially separated from the rotor chamber in which the rotor 4 rotates. For this purpose, the spring and / or damping devices 7a, 7b can be supported on a base-side metal sheet or carrier of the housing 8 of the laboratory centrifuge 1. The opposite base of the spring and / or damping devices 7a, 7b is supported on the drive 3 in an end region of the drive 3, which faces away from the rotor 4. For this purpose, the housing 11 of the drive 3 may have suitable flanges 10a, 10b to which the spring and / or damping devices 7a, 7b are fastened. Ideally, the centrifugal strand 2 does not have an imbalance with respect to the longitudinal and / or rotational axis 6. However, an imbalance may result, for example, from defects or damage to the drive 3 or the rotor 4 of the centrifugal strand 2, damage to at least one product or improper or non-rotationally symmetrical assembly of the rotor 4 with products.

For centrifugation, the rotor 4 of the laboratory centrifuge 1 is equipped with products, for which purpose the rotor 4 may be designed as a fixed-angle swing-out or drum rotor. In this case, as far as possible, the products should be arranged rotationally symmetrically on the rotor 4 and / or be distributed over the circumference of the rotor 4 in such a way that there is no imbalance of the rotor 4 with the products.

In the case of an imbalance or eccentric arrangement of the center of gravity of the centrifugal column 2 which results during operation of the laboratory centrifuge 1, a change in the inclination of the longitudinal and / or rotational axis 6 of the centrifugal strand 2 may occur as a result of the elastic support of the centrifugation strand 2. For low rotational speeds of the rotor 4, the orientation of this inclination changes according to the rotation of the rotor 4, so that the longitudinal and / or rotational axis 6 rotates with the rotational speed of the rotor on a conical surface.

Furthermore, for the rotation of the rotor 4 in the event of an imbalance of the rotor 4 and / or the products held on the rotor 4 as a result of the centripetal acceleration caused by the imbalance, a radial movement to the longitudinal and / or rotational axis 6 occurs and with the rotation of the rotor 4 revolving unbalance force. On the one hand, this rotating imbalance force leads to a likewise circumferential deflection of the centrifugation strand 2, which is oriented transversely to the longitudinal and / or rotational axis 6. On the other hand, the circumferential imbalance force leads to a change in the inclination of the longitudinal and / or rotational axis 6 of the centrifugal strand 2, which also coincides the rotating unbalance rotates. Taking into account the speed-dependent dynamics of the vibration system 9, corresponding dynamic deflections and inclinations of the centrifugal strand 2 occur whose phase shifts and amplitudes are dependent on the resonance or transmission function of the vibration system 9.

On the side of the drive 3 facing away from the bottom of the housing 8 or the side of the drive 3 facing away from the rotor 4, a sensor board 12 is held on a housing 11 of the drive 3. For the embodiment shown here, this is done via a screwed to the housing 11 of the drive 3 recording and mounting unit 13. From the sensor board 12 extends a wiring harness 14, which may be arbitrary, multi-core, unidirectional or bidirectional, from the recording and fastening unit 13 out, which takes place here in the horizontal direction. At the end remote from the sensor board 12, the wiring harness 14 has a plug 15.

Fig. 2 shows in a three-dimensional view of the sensor board 12 with the outgoing therefrom wiring harness 14 in the receiving and fastening unit 13. The receiving and fixing unit 13 is formed here as an annular disc 17 and has distributed over the circumference through holes 18a, 18b, 18c. Furthermore, the annular disc 17 has on the housing 11 of the drive 3 side facing a radially continuous groove 19 through which extends the wiring harness 14. Finally, the ring on the radially inner side in partial peripheral areas open-edged recesses 20a, 20b, 20c (and another, hidden by the wiring harness 14 recess), which are arranged according to the outer contour of the sensor board 12 on the annular disc 17 and the geometry thereof is that in these recesses 20a, 20b, 20c corners, the sensor board 12 are received with a game, a clearance fit, a transition fit or a press fit. An underside of the sensor board 12 is supported on a bottom of the recesses 20a, 20b, 20c. It is possible that the sensor board 12 is loosely inserted into the annular disc 17, wherein the sensor board 12 is then caught with screwing the washer 17 on the housing 11 of the drive 3 between the bottom of the recesses 20 and the housing 11 of the drive 3. It is also possible that the sensor board 12 is additionally attached to the annular disc 17, which u by any attachment means such as an adhesive, a screw, a clipping u. Ä. Can take place. For the in Fig. 2 illustrated embodiment, the radially inwardly open recesses 20 have an angular cross-section, wherein the angular cross-sections of the recesses 20 complement each other to a rectangle whose dimensions match with a game, a clearance, a transition fit or a press fit with the outer dimensions of the sensor board 12.

The assembly of the sensor board 12 is preferably carried out on the housing 11 of the drive 3 side facing. Here, the thickness of the annular disc 17 and the depth of the recesses 20 is selected such that the electronic and electrical components of the sensor board 12 with a small clearance spaced from the housing 11 of the drive 3 are arranged. For the illustrated embodiment, a ventilation of the sensor board 12 from the bottom region of the laboratory centrifuge 1 through gaps 21a, 21b, 21c, 21d takes place.

Fig. 3 FIG. 2 shows highly schematically a possible fitting of the sensor board 12. Accordingly, the sensor board 12 has a first inclination sensor 22, a second inclination sensor 23, a first acceleration sensor 24, a second acceleration sensor 25, a temperature sensor 26, a magnetic field sensor 27, a plug connector 28, to which can be connected via a corresponding connector of the wiring harness 14, an electronic control unit 29 and a 9-axis sensor 30th

The magnetic field sensor 27 can detect an inclination to a magnetic field of the earth.

It is also possible that the magnetic field sensor 27 or one of the inclination sensors 22, 23 detects the magnetic field of a permanent magnet 31. The permanent magnet 31 is fixed to the housing 8 of the laboratory centrifuge 1. In the event that, as in Fig. 1 shown, the magnetic field sensor 27 is arranged with the sensor board 12 in the bottom region of the laboratory centrifuge 1 on the housing 11 of the drive 3, the permanent magnet 31 is also disposed in the bottom region of the laboratory centrifuge 1. For example, the permanent magnet 31 is attached to a bottom plate or a bottom-side strut of the laboratory centrifuge 1. The magnetic field sensor 27 detects the strength or flux density of the magnetic field of the permanent magnet 31 or an orientation of the magnetic field of the permanent magnet 31, whereby the distance of the magnetic field sensor 27 from the permanent magnet 31 and / or the inclination to the magnetic field of the permanent magnet 31 and thus the Incident of the longitudinal and / or rotational axis 6 relative to the housing 8 is detected.

In the context of the invention, it can be determined on the basis of the measurement signals by means of the control unit 29 whether the axis of rotation of the rotor 4 corresponds to the principal axis of inertia of the rotor 4 with the products held thereon. Deviations from this are detected by means of the control logic as imbalance, which leads to vibrations. This can be done a qualitative and / or quantitative detection of imbalance. If an existing unbalance detected, there is a controlled deceleration of the drive 3. It can be initiated an emergency braking procedure, then on the issue of an example. Visual or audible error message can interact with the user, so that an existing risk due to imbalance can be recognized by the user or a higher-level machine.

It is possible that a release of a lid of the laboratory centrifuge 1 for enabling the opening of the laboratory centrifuge 1 with the detection of an imbalance takes place only when the rotor 4.

It is also possible that a warning of the user after the assembly of the rotor 4 with the products before driving the rotor 4 takes place, if an imbalance could arise during operation. This may be the case with a missing product, a product in a wrong place or a non-uniform loading of the rotor 4 with the products.

Another possible cause of the occurrence of an imbalance may be a bent, tilted, tilted or lacking attachment of the rotor 4.

It is also possible that the measured measurement signals or a result of the evaluation thereof is used as a process parameter. Thus, for example, in an automated loading and unloading laboratory centrifuge 1 or also a manually loaded and unloaded laboratory centrifuge 1, it is possible to monitor measured values or evaluation results within a predetermined tolerance range for different cycles of the laboratory centrifuge 1 with a plurality of sets of samples with the desired same configuration must result. Here, for example, amplitudes, waveforms, rectified and integrated waveforms u. Ä. be compared with predetermined tolerance ranges. It is also possible to monitor whether the result of the evaluation by the control unit for a determined unbalance or an inclination of a longitudinal and / or rotational axis of the centrifugal strand 2 is within a tolerance range. If a measuring signal or a result of the evaluation lies outside the tolerance range, an error message or an error entry can be output. It is also possible for a modified component (for example another rotor and / or other products attached to the rotor or an altered number of products mounted on the rotor) to be detected without this necessarily being necessary to exceed a threshold value for an admissible unbalance , In this case, information may be given to the user or a higher level automated machine that should be checked for placement.

As sensors inductive sensors, a microsystem (MEMS), acoustic sensors or optical sensors can be used. Position sensors such as a gyroscope or a magnetometer and / or acceleration sensors are primarily used, and these may have different sensitivities and / or frequency ranges as explained above.

An evaluation of the measurement signals can take place in the time domain or in the frequency domain. In this case, a coordinate transformation between rotor and drive movements can take place. Other device parameters such as, for example, the rotor speed, the current consumption of the drive or RZB can also be included in the evaluation.

An evaluation can be made on the sensor board 12 and / or in a control unit of the laboratory centrifuge 1 or even externally from the laboratory centrifuge 1.

It is possible that a fixed threshold value is defined as the threshold value for a measured inclination or a measured acceleration, a calculation of a dynamic threshold value takes place and / or a temporal integration of the measured inclination or the measured acceleration and a shutdown occurs when a limit value is exceeded.

It is also possible that when determining an imbalance on the basis of a measurement signal for the temperature, a change in the spring stiffness and / or the damping of the spring and / or damping device 7, over which the centrifugal strand 2 is supported relative to the housing 8, is taken into account.

The 9-axis sensor can be a sensor that detects accelerations in all spatial directions, inclinations in all spatial directions and a magnetic field in all spatial directions.

If a measured inclination does not change with slow rotation of the rotor 4, this inclination is based on a non-horizontal installation of the laboratory centrifuge 1. If, however, this inclination changes with the rotation of the rotor 4, the non-rotationally symmetrical assembly or an imbalance of the rotor 4 is responsible for this , It can then be generated a corresponding error message.

The individual sensors or the sensor board 12 may already be equipped with an AD converter or AD conversion takes place after transmission of the measurement signals via the wiring harness 14.

Preferably, an evaluation of the measurement signals takes place at least partially by using a fast Fourier transformation (FFT). Under certain circumstances, in the result of the FFT, the amplitude of the signal in the case of upper and / or lower waves increases to the fundamental frequency dependent on the rotational speed of the rotor 4, so that the spectral lines of the FFT for the upper and / or lower waves also indicate an imbalance may also be deducted from their amount. It is also possible that a DC component of the detected signals is separated from an AC component via an FFT.

It is also possible that a high-pass filtering, a low-pass filtering or a band-pass filtering of the measuring signals takes place. A bandpass filter whose center frequency corresponds to the frequency resulting from the rotational speed of the rotor 4 or which corresponds to an upper or lower wave of this frequency is preferably used.

It is also possible that by means of arranged on the sensor board 12 control unit 29, a conditioning of the measurement signals of the sensors already takes place, for example, can be done so that for different rotors 4 and sensor boards 12 each an adaptation to the different types of rotors and the used Sensors are performed by the control unit 29 and then via the wiring harness 14 already standardized output signals can be transmitted, which can then be evaluated by a control unit of the laboratory centrifuge 1 or an external control unit.

1. a) Wird eine Unwucht erkannt, kann ein Zentrifugieren unterbunden werden oder eine eingeleitete Zentrifugation abgebrochen werden und/oder es kann eine Information an den Nutzer gegeben werden.
2. b) Nach Erfassung einer nicht gewünschten Neigung im Stillstand kann eine entsprechende Mitteilung an den Nutzer erfolgen und/oder es kann der Antrieb des Rotors deaktiviert werden.
3. c) Es kann ein entsprechender Eintrag in einem Speicher (des Rotors oder der Laborzentrifuge) erfolgen, um die Historie des Zentrifugierens und/oder des Rotors zu dokumentieren.
4. d) Tritt ein Defekt, insbesondere ein Motordefekt, auf, kann entsprechend der Dokumentation gemäß c) eine Fehleranalyse erfolgen.
5. e) Möglich ist eine Anpassung der Lebensdauer des Rotors und/oder der beteiligten Bauelemente je nach dokumentiertem Verlauf der Zentrifugationsprozesse. Ebenfalls möglich ist eine Anpassung etwaiger Serviceintervalle.
6. f) Möglich ist auch, dass geeignete Maßnahmen zur Reduzierung der Auswirkungen einer etwaigen Unwucht getroffen werden. So kann beispielsweise eine Anpassung von Magnetlagern zur Lagerung des Rotors erfolgen.
7. g) Eine Wechselwirkung mit einem Deckelschloss ist möglich, so dass beispielsweise das Öffnen des Deckels unterbunden wird, wenn eine Unwucht erkannt wird und sich der Rotor in der Laborzentrifuge noch dreht.
8. h) Tritt eine sprunghafte Änderung des Beschleunigungssignals oder einer charakteristischen Kenngröße während des Betriebs des Rotors auf, wird dies als Indiz insbesondere für ein Versagen eines Behälters, bspw. einen Bruch eines Röhrchens, gewertet. Hintergrund ist hier, dass bei einer im Betrieb auftretenden Unwucht von bspw. 100 gr mittels bekannter Laborzentrifugen eine Notbremsung erst eingeleitet werden kann, wenn dies bereits zu spät ist, so dass es zur Zerstörung der Laborzentrifuge kommen kann. Erfindungsgemäß kann bei einem Versagen eines Behälters bereits relativ früh, also bei einer kleinen entstehenden Unwucht, ein Versagen des Behälters erkannt werden, womit eine Notbremsung früher erkannt werden kann.

The evaluation can then be used to automatically initiate the following measures:

1. a) If an imbalance is detected, centrifuging can be stopped or an initiated centrifugation can be stopped and / or information can be given to the user.
2. b) After detection of a non-desired inclination at standstill, a corresponding message to the user and / or it can be disabled, the drive of the rotor.
3. c) A corresponding entry in a memory (of the rotor or the laboratory centrifuge) can be made to document the history of the centrifuging and / or the rotor.
4. d) If a defect, in particular a motor defect, occurs, an error analysis can be carried out according to the documentation according to c).
5. e) It is possible to adapt the service life of the rotor and / or the components involved depending on the documented course of the centrifugation processes. It is also possible to adjust any service intervals.
6. f) It is also possible to take appropriate measures to reduce the effects of any imbalance. For example, an adaptation of magnetic bearings for mounting the rotor can be done.
7. g) An interaction with a lid lock is possible, so that, for example, the opening of the lid is prevented when an imbalance is detected and the rotor still rotates in the laboratory centrifuge.
8. h) If a sudden change in the acceleration signal or a characteristic parameter occurs during operation of the rotor, this is interpreted as an indication, in particular for a failure of a container, for example a breakage of a tube. The background here is that an emergency unbalance of, for example, 100 g occurring during operation by means of known laboratory centrifuges emergency braking can be initiated only if this is already too late, so that it can lead to the destruction of the laboratory centrifuge. According to the invention, a failure of the container can already be detected relatively early in the event of a failure of a container, that is to say with a small imbalance arising, with which emergency braking can be detected earlier.

Notwithstanding the illustrated embodiment, the sensor board 12 may be arranged in a side region of the housing 11 of the drive 3 or even integrated into the drive 3.

If in the context of the invention of an acceleration of the drive or an orientation of the drive is mentioned, this preferably relates to an acceleration or alignment of the housing of the drive.

For an embodiment of the invention, an evaluation of the measurement signals, in particular for the determination of an imbalance, in a low speed range, in particular a speed range below 3,000 or 4,000 rpm, by means of an acceleration sensor, while in a speed range above 3,000 U / min or above 4,000 rpm up to the maximum rotational speed of the laboratory centrifuge 1 an evaluation takes place on the basis of the measurement signal of a tilt sensor, which can detect in particular a transient transient response in the case of a tube break even at the high speeds mentioned.

LIST OF REFERENCE NUMBERS

1

laboratory centrifuge

2

Zentrifugationsstrang

3

drive

4

rotor

5

Drive and / or rotor shaft

6

Longitudinal and / or rotational axis

7

Spring and / or damping device

8th

Housing laboratory centrifuge

9

vibration system

10

flange

11

Housing drive

12

sensor board

13

Receiving and fastening unit

14

wiring harness

15

plug

16

gravitational acceleration

17

washer

18

Through Hole

19

groove

20

recess

21

gap

22

first position and / or tilt sensor

23

second position and / or tilt sensor

24

first acceleration sensor

25

second acceleration sensor

26

temperature sensor

27

Magnetic field sensor

28

Connectors

29

control unit

30

9-axis sensor

31

permanent magnet

Claims (16)

Laboratory centrifuge (1) with a centrifugal strand (2), which has a drive (3) and a rotor (4) driven by the drive (3), wherein the centrifugation strand (2) has at least one spring and / or damping device (7). relative to a housing (8) is supported, characterized in that at least one inclination sensor (22, 23) is present, which detects an alignment of a longitudinal and / or rotational axis (6) of the centrifugal strand (2). Laboratory centrifuge (1) according to claim 1, characterized in that the inclination sensor is a gyroscope sensor and the gyroscope sensor is held by a housing (11) of the centrifugal strand (2). Laboratory centrifuge (1) according to claim 1, characterized in that the inclination sensor comprises a magnetic field sensor (27) and a magnetic field generating permanent magnet (31). Laboratory centrifuge (1) according to one of the preceding claims, characterized in that two inclination sensors are present, wherein a) a tilt sensor is a gyroscope sensor, which is held on a housing of the centrifugal strand (2), and b) an inclination sensor comprises a magnetic field sensor and a magnetic field generating permanent magnet. Laboratory centrifuge (1) according to one of the preceding claims, characterized in that a) at least two acceleration sensors (24, 25) are present, which measure an acceleration of the drive (3) with different sensitivities and / or in different frequency ranges, b) at least two inclination sensors (22, 23) are present, which measure an inclination of the drive (3) with different sensitivities and / or in different frequency ranges, c) at least one sensor (27) is present, which measures the orientation of the centrifugal strand (2) with respect to a magnetic field of the earth or with respect to the acceleration due to gravity (16), d) at least one sensor is present, which detects a rotational angle, an angular velocity or an angular acceleration of a drive shaft (5) of the drive (3), e) a temperature sensor (26) and / or f) a 9-axis sensor (30) are present / is. Laboratory centrifuge (1) according to one of the preceding claims, characterized in that the sensors are at least partially disposed on a sensor board (12) / is. Laboratory centrifuge (1) according to one of the preceding claims, characterized in that the sensors at least partially and / or the sensor board (12) on the rotor (4) facing away from the centrifugal strand (2) or the drive (3) are arranged / is , Laboratory centrifuge (1) according to one of the preceding claims, characterized in that an electronic control unit (29) is present, which processes the measuring signal or the measuring signals of the sensors. Laboratory centrifuge (1) according to claim 8, characterized in that the electronic control unit (29) is equipped with control logic which a) determines whether the laboratory centrifuge (1) is positioned so that the drive axis of the drive (3) or a main axis of inertia of the rotating components of the centrifugal strand (2) is aligned in the direction of the gravitational acceleration vector (16), and / or b) determines an imbalance of the rotating components of the centrifugation strand. Laboratory centrifuge (1) according to claim 8 or 9, characterized in that the electronic control unit (29) is equipped with control logic, which differs on the basis of the measurement signals determined by the sensors, whether a) the laboratory centrifuge (1) is set up so that the drive axis of the drive (3) or a principal axis of inertia of the rotating components of the centrifugal column (2) is not oriented in the direction of the acceleration due to gravity (16), or b) an imbalance of the rotating components of the centrifugation strand (2) is present. Laboratory centrifuge (1) according to one of claims 8 to 10, characterized in that the electronic control unit (29) is equipped with control logic, which in the presence of an error criterion a) generates an error message, b) interrupts or changes the operation of the laboratory centrifuge (1) and / or c) stops the operation of the laboratory centrifuge (1). Laboratory centrifuge (1) according to one of claims 8 to 11, characterized in that the electronic control unit (29) is equipped with control logic which a) controls or regulates a position of a balancing mass to compensate for an imbalance of the rotating components of the centrifugal strand and / or b) at least one bearing, at least one compensation device and / or at least one spring and / or damping device (7) so controls or controls that an effect of unbalance of the rotating components of the centrifugal strand and / or non-parallel alignment of the drive axle of the drive ( 3) or a principal axis of inertia of the rotating components of the centrifugal strand (2) is at least mitigated for acceleration of gravity. Laboratory centrifuge (1) according to one of claims 8 to 12, characterized in that the electronic control unit (29) is equipped with control logic which detects a failure of at least one product and a resultant imbalance of the rotor (4). Laboratory centrifuge (1) according to one of claims 8 to 13, characterized in that the electronic control unit (29) is equipped with control logic which carries out a temperature compensation of a measuring signal of another sensor based on a temperature measured with a temperature sensor (26). Laboratory centrifuge (1) according to one of claims 8 to 14, characterized in that the electronic control unit (29) is equipped with control logic, which at a) the determination and / or evaluation of a size of an imbalance of the rotating components of the centrifugation strand and / or b) a determination and / or evaluation of a non-parallel orientation of the longitudinal and / or rotational axis of the centrifugal strand (2) or a principal axis of inertia of the rotating components of the centrifugal force (2) for acceleration of gravity takes into account the temperature measured by a temperature sensor. Laboratory centrifuge (1) according to one of claims 8 to 15, characterized in that the electronic control unit (29) is equipped with control logic based on a) the measured signals measured by the sensors, b) the evaluation of the measuring signals and / or c) of error criteria an adaptation of a service life and / or a service interval of the laboratory centrifuge (1), the drive (3) or the rotor (4) makes.

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