EP3505258B1 - Laboratory centrifuge - Google Patents

Description

Laboratory centrifuges are used, for example, in biotechnology, the pharmaceutical industry, medical technology and environmental analysis. A laboratory centrifuge is used to centrifuge a product, in particular a sample container with a sample or substance arranged therein, or a large number of such products. As a result of the centrifugation, accelerations acting on the product should be generated so that a mixture of substances formed by the sample or the substance is broken down into components of different densities. Depending on the chemical and / or physical properties of the mixture of substances, a targeted control of the pressure and / or temperature conditions can also take place during centrifugation. To name just a few examples, the use of a laboratory centrifuge in connection with a polymerase chain reaction (PCR), determination of hematocrit, cytological examinations or the centrifugation of microtiter, blood bags, petroleum vessels or blood vessels, etc. the like.

Laboratory centrifuges have a centrifugation line. In the centrifugation strand, a rotor is driven by a drive. The products are held on the rotor, for which so-called fixed-angle, swing-bucket or drum rotors can be used (see www.sigmalzentrifugen.de). The drive rotates the rotors with the products at high speeds in order 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 the centrifugation of the products. For this purpose, for example, the rotor can be driven at a speed of more than 4,000 rpm, more than 5,000 rpm, more than 10,000 rpm, more than 15,000 rpm or even more than 20,000 rpm.

The operation of the centrifugation strand is controlled or regulated and monitored by controlling or regulating and monitoring the electrical application of the Drive. For example, the drive speed and / or the drive torque of the drive can be controlled or regulated, it also being possible to follow predetermined curves for the drive speed or the drive torque. The centrifugation strand is supported against a housing of the laboratory centrifuge via spring and / or damping devices. A deflection or acceleration of the centrifugation strand can be detected via a sensor in order, for example, in the event of an unbalance of the rotor to be able to detect vibrations of the centrifugation strand relative to the housing.

STATE OF THE ART

The pamphlet DE 195 39 633 A1 describes it as known to actuate a switching element as a function of a deflection of a resiliently mounted centrifugation strand, whereby it is concluded that an imbalance is present. The problem in DE 195 39 633 A1 In the case of such a deflection-based detection of an imbalance, it is considered that in the event of an imbalance that may only arise at a higher speed, in particular due to the breakage of a test tube, the imbalance does not lead to the formation of a large deflection due to the high speed, which means for the At high speeds, it is not possible to detect the imbalance via a switching element actuated via the deflection. The reason given for this is that the gyroscopic precision emanating from the rotor can both increase and decrease the extent of the deflection, so that the unbalance is detected prematurely or not at all. Furthermore, the necessary high adjustment effort is criticized in the known switching elements based on a deflection. With this in mind, suggests DE 195 39 633 A1 suggest that an acceleration of the centrifugation strand is detected by an electrical acceleration sensor or a deflection of the centrifugation strand is determined via a displacement sensor. This should result in a simple calibration in production, since under certain circumstances a basic setting or calibration can only be carried out by means of a normal run and an unbalance run. The measurement signal is preferably evaluated by means of a band filter, the center frequency of which corresponds to the rotational frequency of the rotor. If the sensor detects an unbalance of a sufficient size, an alarm device or a disconnection device is actuated. The use of an optoelectronic sensor is proposed as the displacement sensor.

The pamphlet DE 10 2011 100 044 B4 suggests providing a support ring on a rotor. For the purpose of identifying different rotors, the Area of the support ring at different points distributed over the circumference, which are specific for the different rotors, magnets arranged. Magnetic sensors are arranged adjacent to the support ring in a rotor chamber of the laboratory centrifuge, from the measurement signals of which the number and circumferential angle of the magnets arranged on a rotor can be determined, thus enabling the rotor to be identified. While the previously explained identification of the rotor takes place when the rotor is stationary, it beats DE 10 2011 100 044 B4 also suggests that the magnetic sensors can also be used while the laboratory centrifuge is in operation to detect an inclined position of the rotor's axis of rotation, which leads to a change in the distance between the magnets and the magnetic sensors, from which it is concluded that an imbalance is present.

The pamphlet DE 10 2014 116 527 A1 discloses the use of a rotation angle sensor, a displacement sensor and three acceleration sensors, each of which is responsible for a spatial direction. An imbalance should be detected at low speeds by means of the displacement sensor, while at higher speeds above 1,000 rpm the detection should be based on the measurement signal of an acceleration sensor. In addition, the centrifugation line can interact with an emergency switch, via which an emergency shutdown of the laboratory centrifuge is possible. The measurement signal of an acceleration sensor or the displacement sensor is compared with characteristic curves stored in a control unit. If an amplitude of a measurement signal is greater than a limit value dependent on a first characteristic curve, this signals an imbalance which does not yet represent any immediate danger to the safety of the laboratory centrifuge or the user. In this case, an acoustic or visual warning signal can be given to the user. If, on the other hand, an amplitude of the measurement signal exceeds a second limit value, which is specified by a second stored characteristic curve, this is seen as an indication of an imminent danger and an immediate need for action, which can result in an automatic emergency shutdown of the laboratory centrifuge. The characteristic curves mentioned can be speed-dependent. The control unit can have a data logger that records the measurement signals. The measurement signals recorded in this way can then be read out via a USB port after the laboratory centrifuge has been operated 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 that can be mounted directly on an electronics board that is fastened in the area of a lower motor bearing of the drive near the drive shaft.

The pamphlet DE 203 07 913 U1 discloses the mounting of a rotor of a laboratory centrifuge via magnetic bearings. On the one hand, the size and position of an imbalance in the rotor can be deduced from the electrical operating variables of the magnetic bearings. On the other hand, with an imbalance 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 the imbalance is compensated.

DE 10 2015 102 476 A1 discloses the mounting of a drive shaft carrying a rotor of an electric motor in two motor bearings. One engine mount is supported by a bell-shaped housing, while the other engine mount is supported on spring elements via a coupling body that represents a large inertial mass. The oscillating movement of the drive shaft is measured adjacent to the two motor bearings using a displacement, speed or acceleration sensor. The stator of the electric motor has windings which, depending on the measurement signals from the displacement, speed or acceleration sensors, are activated so that they can counteract the vibrations of the drive shaft. Tilting of the drive shaft can also be determined from a difference between two displacement signals, which are measured by means of corresponding displacement sensors arranged in the area of the engine bearings. A speed sensor can be arranged in an end region of the drive shaft facing a floor, a Hall sensor also being able to be used here, which detects a speed and a rotation angle and a direction of rotation of the drive shaft.

CN 105 750 095 A discloses a centrifuge that is supported on tilt compensating actuators. Strain sensors arranged on the rotor axis determine a bending load on the rotor shaft. The inclination of the centrifuge is automatically adjusted by means of the actuators so that a bending load on the rotor shaft is counteracted.

DE 10 2007 042 488 A1 discloses a separator with a centrifuge drum and a rotor, the rotor being coupled to a damping element for damping imbalances and vibrations. Damping of the damping element can be controlled or regulated, with a displacement or tilting of the rotor, based on which the damping is controlled or regulated, being measured by means of at least two acceleration sensors or by means of two displacement sensors.

DE 31 15 590 A1 discloses a method for detecting misalignment of a centrifuge rotor. The centrifuge rotor is irradiated with a bundle of rays, such as a light beam, and radiation reflected on the centrifuge rotor is measured with a sensor. If the rotor is aligned as specified, the reflected radiation on the sensor is uniform. In the event of misalignment, for example as a result of a vibration of the centrifuge rotor, the beam is reflected in such a way that it generates a non-uniform signal at the sensor.

OBJECT OF THE INVENTION

The present invention is based on the object of proposing 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 according to the invention with the features of the independent patent claim. Further preferred embodiments according to the invention can be found in the dependent claims.

DESCRIPTION OF THE INVENTION

The present invention is based in particular on the following findings:
If a centrifugation strand of the laboratory centrifuge is elastically supported on a housing of the laboratory centrifuge via spring and / or damping devices, an imbalance of the rotating components of the centrifugation strand and a non-coaxial alignment of a longitudinal or rotation axis of the centrifugation strand lead to the acceleration of gravity or the gravitational field of the earth to a static and / or dynamic deflection of the centrifugation strand relative to the housing of the laboratory centrifuge. This can be explained below using extreme considerations on 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 acceleration due to gravity, the center of gravity of the centrifugation strand may be arranged eccentrically to the spring and / or damping devices, which results in a first tilting moment, which strives to reduce the deviation in the alignment of the To enlarge the longitudinal and / or rotation axis of the centrifugation strand compared to the acceleration of gravity. This first tilting moment acts in principle both when the centrifugation strand is at a standstill and when the rotating components of the centrifugation strand are rotating and is independent of whether the rotating components of the centrifugation strand are unbalanced. In principle, the orientation of the first tilting moment does not change with a rotational movement of the rotating components of the centrifugation strand and the amount of the first tilting moment is also independent of a speed of rotation of the rotating components of the centrifugation strand. On the other hand, there is a second tilting moment (even with a parallel alignment of the longitudinal and / or rotation axis of the centrifugation strand) as a result of any imbalance in the rotating components of the centrifugation strand. This second tilting moment is small when the rotating components are at a standstill and results from the product of the imbalance radius (i.e. the distance between the imbalance and the axis of rotation) and the imbalance mass. The second breakdown torque increases sharply with the increase in speed.

In addition, the movement, force and moment ratios on the centrifugation line are heavily dependent on the dimensioning of the spring and / or damping devices via which the centrifugation line is supported on the housing of the laboratory centrifuge.

This can be explained in a simplified manner for extreme designs of the spring and / or damping devices: For a negligible spring and / or damping device, the centrifugation strand is gimbaled for a simplified view, so that the longitudinal and / or rotation axis of the centrifugation strand is automatically parallel to the acceleration due to gravity can align. In contrast, an infinitely high stiffness and damping of the spring and / or damping devices ensures that the alignment 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 with respect to the The acceleration due to gravity depends exactly on how "horizontally" the housing of the laboratory centrifuge and thus the centrifugation line are positioned).

Finally, the above consideration of the two tilting moments is only a strong simplification, which only takes into account the actually existing complex conditions in a rough approximation:
In fact, the rotating components of the centrifugation strand form a gyroscope, the spring and / or damping devices specifying boundary conditions of the gyroscope. For the extreme case of the vanishing stiffness and damping of the spring and / or damping devices, the centrifugation strand forms a free top, while for finite values of the stiffness and damping of the spring and / or damping devices, the centrifugation strand forms a tied top. The dynamics of the gyro is complex and is described by Euler's gyro equations. Here, the dynamics of the alignment of the longitudinal and / or rotational axis of the centrifugation strand influences a deviation moment (measure of the gyro's efforts to change its axis of rotation when the gyro does not rotate around one of its main axes of inertia) and a gyroscopic moment. The centrifugation strand can perform complex nutation movements and precession movements, with the movement of the axis of rotation of the centrifugation strand being able to take place on a nutation cone and / or a coral pole cone.

The sensors and evaluation methods known from the prior art do not take these complex processes into account. Rather, according to the state of the art, regardless of the cause of the deviation of the rotational movement of the rotor from a fixed axis of rotation (i.e. regardless of whether the laboratory centrifuge is not set up exactly horizontally or there is an imbalance in the rotating components of the centrifugation strand), a comparison of a measured deflection is made or the acceleration of the centrifugation strand with threshold values specified a priori.

According to the invention, an inclination sensor is used for the first time 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 alignment of the longitudinal and / or rotational axis of the centrifugation strand. On this basis, for the first time there is a measurement signal for the alignment of the longitudinal and / or rotation axis of the centrifugation strand, which provides alternative or additional evaluation options for static and / or dynamic changes in the Provides location and / or alignment of the centrifugation strand, which in particular provides alternative or additional and improved options for identifying an inadequate 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 centrifugation strand. To name just one example that does not restrict the invention, the evaluation can also take into account the aforementioned gyroscopic effects on the basis of the measurement signal from the inclination sensor.

According to the invention, the inclination sensor is a gyroscope sensor. 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 also a change in inclination of the longitudinal and / or rotational axis of the centrifugation strand. A gyroscope, which can also be referred to as a gyro stabilizer or gyro instrument, contains a rotating symmetrical measuring gyro, which is mounted in relation to a suspension in such a way that its axis of rotation does not change when the suspension is pivoted as a result of the measuring gyro's pivoting relative to the suspension of the measuring gyro. The suspension can be, for example, a cardanic suspension. A pivoting of the suspension relative to the measuring gyro is converted into a measuring signal with a gyroscope sensor. When the gyroscope sensor is used according to the invention, 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 can also not have a rotating measuring gyro and can also be used within the scope of the invention, are used today in smartphones, tablets and game consoles, for example.

For a special embodiment of the invention, two inclination sensors are present in the laboratory centrifuge. In this case, an inclination sensor is the gyroscope sensor, which is held on a housing of the centrifugation line. In contrast, the other inclination sensor is designed with a permanent magnet and a magnetic field sensor that interacts with the magnetic field of the permanent magnet. The two inclination sensors can be used redundantly here. However, it is also possible for the two inclination sensors based on a different measuring principle to have different sensitivities and / or frequency ranges for recording a measuring signal.

By means of an inclination sensor, which is designed as a magnetic field sensor, the strength and / or orientation of a magnetic field is detected and converted into a measurement signal. Such an inclination sensor also has a permanent magnet. The permanent magnet generates a magnetic field, the strength and / or orientation of which 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 is held adjacent to the magnetic field sensor on a housing of the laboratory centrifuge. Alternatively, it is possible for the permanent magnet to be attached to the housing of the centrifugation strand, while the magnetic field sensor is held on the housing of the laboratory centrifuge. If there is then 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 the permanent magnet, which increases the distance between the magnetic field sensor and the permanent magnet and / or changes the alignment of the magnetic field generated by the permanent magnet with respect to the magnetic field sensor. In this embodiment, conclusions can be drawn about the inclination of the centrifugation strand relative to the housing on the basis of the strength of the magnetic field and / or the direction of the magnetic field detected by the magnetic field sensor.

If the magnetic field sensor for a possible embodiment is based on the detection of a magnetic flux density (so-called magnetometer), any type of sensor (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, etc. Ä. Be used.

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

The signal processing of a measurement signal from an acceleration sensor usually only has 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 is usually the speed of the rotor or sub- and / or superharmonics corresponds to this speed). The acceleration amplitude measured by an acceleration sensor thus increases with it an increase in the frequency, ie with an increase in the drive speed of the rotor. 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 oscillation system which is formed with the centrifugation strand and its support via the at least one spring and / or damping device. According to the state of the art, a sensitivity of the acceleration sensor must be adapted or optimized for all frequencies and amplitudes that occur. In connection with the limited resolution of the digital processing of the measurement signal of the acceleration sensor for speed ranges of the rotor with small accelerations occurring, this can lead to poor resolution of the measurement signal and a poor signal-to-noise ratio. In addition, known acceleration sensors and / or signal processing used for evaluation for the measurement signal of the acceleration signal can also only have 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 one sensor type of an acceleration sensor with which the acceleration of the centrifugation strand is detected in one or more spatial directions with a given sensitivity in the given 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, with the two acceleration sensors preferably measuring the acceleration in the same spatial direction. According to the invention, two sensors of different sensor types are 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 according to the invention is based on the knowledge that when using a single sensor type of an acceleration sensor with a given sensitivity and a given frequency range, this sensor type must be selected so that the sensitivity and the frequency range of the sensor type are selected so that the acceleration sensor is in all relevant areas Operating situation supplies sufficiently good measurement signals to be able to carry out the necessary evaluation. For example, the acceleration sensor must have sufficiently good measurement signals both at low speeds (and, under certain circumstances, large deflections of the centrifugation strand) and at high speeds (and under certain circumstances small ones) Deflections of the centrifugation strand) deliver what is only possible to a limited extent. In contrast, the sensors of different sensor types used according to the invention with different sensitivities and / or different frequency ranges can each be adapted to different operating states (or a respectively assigned operating state range) of the laboratory centrifuge. For example, an acceleration sensor can be designed in such a way that it emits a measurement signal (in particular with a measurement error of less than 10%, less than 5% or less than 3%) both for a frequency of 0 (i.e. a constant component) and for low frequencies (e.g. for frequencies from 0 to 50 Hertz, 0 to 100 Hertz, 0 to 200 Hertz or 0 to 500 Hertz) while another acceleration sensor then generates a measurement signal (in particular with a measurement error of less than 10%, less than 5% or less than 3%) is generated in a frequency range which is at least partially above the frequency range of the first-mentioned sensor and, for example, in a frequency range above 50 Hertz, 100 Hertz, 150 Hertz or 200 Hertz or 500 Hertz.

For example, if the first acceleration sensor detects an acceleration in a low frequency range, as soon as the laboratory centrifuge starts up, the first acceleration sensor can be used to monitor whether a longitudinal and / or rotational axis of the centrifugation strand is aligned parallel to the gravitational acceleration vector and / or the rotating components of the Centrifugation strand have an imbalance. On the other hand, the second acceleration sensor can also be responsible for monitoring the acceleration for higher or maximum rotational speeds. Under certain circumstances, the second acceleration sensor can be used to detect with a relatively high sensitivity if a product fails for higher or maximum rotational speeds (e.g. a sample tube breaks), so that without an initial unbalance of the rotor, an unbalance only results when the laboratory centrifuge is in operation can be effective only briefly or permanently. Under certain circumstances, an evaluation can also be advantageous such 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, the inclination sensor detects that the longitudinal and / or rotational axis of the centrifugation strand is inclined and the acceleration sensor generates a, for example, harmonically oscillating measurement signal in one spatial direction, it can be concluded with greater certainty than the prior art that a There is an imbalance which, on the one hand, leads to the inclination detected by the inclination sensor and, on the other hand, as a result of the imbalance rotating around the longitudinal and / or The axis of rotation of the centrifugation strand leads to the oscillating measurement signal of the acceleration sensor.

For an alternative or cumulative solution encompassed by the invention, the centrifugation strand has a sensor which is based on a sensor principle that has not yet been used for a laboratory centrifuge: For this embodiment, a sensor is used that aligns the drive with respect to a magnetic field Earth measures. A Hall sensor, for example, can be used for this purpose. On the basis of a measurement signal that is determined in this way and relates to the alignment of the drive with respect to the earth's magnetic field, 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, given the sensor principle used. On the other hand, this sensor can also be used to detect tilting of the centrifugation strand during operation of the laboratory centrifuge as a result of the vibrating support of the same via the spring and / or damping devices relative to the housing and / or as a result of a static imbalance without rotation of the rotor or a dynamic unbalance excitation when the rotor rotates become and u. U. the extent of the 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) there is at least one sensor which detects an angle of rotation, an angular speed or an angular acceleration of a drive shaft of the drive.

A temperature sensor can also 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) from the other sensors. This temperature sensor then preferably does not measure the temperature in the rotor chamber or the temperature inside the drive, but rather the temperature to which the sensors are exposed.

Finally, it is alternatively or cumulatively possible that a 9-axis sensor is present.

On all of the aforementioned sensors, so in particular the inclination sensors, the gyroscope sensor, the magnetic field sensor, the permanent magnet, the acceleration sensors, the sensor for detecting the alignment of the drive with respect to a magnetic field of the earth, the Sensor for detecting an angle of rotation, an angular speed or an angular acceleration of a drive shaft of the drive, the temperature sensor and / or the 9-axis sensor, is referred to below with the common generic term "sensor".

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

In principle, the sensor board can be arranged at any point on the centrifugation line or the housing of the drive. However, it is preferably located on the side of the centrifugation strand facing away from the rotor, in particular the housing of the drive. On the one hand, this has the advantage that the sensor board does not have to extend, for example, in the area of a rotor chamber, which reduces the installation space required here. On the other hand, for the arrangement of the sensor board on the side of the drive facing away from the rotor, it may also be avoided that when the laboratory centrifuge is operated, a temperature increase in the rotor chamber during operation due to the high speed of the rotor does not reach the temperature of the possibly sensitive electrical and electronic components on the sensor board. In this way, under certain circumstances, a temperature influence on the accuracy of the measurement signals from the sensors of the sensor board can at least be reduced.

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

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

The electronic control unit can have any control logic required for operating and evaluating the sensors. 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 assigned memory unit, by means of which the electrical measurement signal provided by the sensor is converted. The signal converted in this way can then also be evaluated by the control unit, by another control unit of the laboratory centrifuge or even by a control unit arranged outside the laboratory centrifuge to which the signal is transmitted in a wired or wireless manner.

For an embodiment according to the invention, the control logic determines whether the laboratory centrifuge is set up in such a way 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 gravitational acceleration vector. This can take place, for example, on the basis of the detection of a deviation moment by the inclination sensors used or by evaluating at least one inclination sensor and / or a further sensor in some other way.

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

However, it is also possible that an evaluation is carried out in such a way that the extent of the deviation in the alignment of the drive axis of the drive or the main axis of inertia and / or the The size of an imbalance in the rotating component of the centrifugation strand or its angular position with regard to the rotation about the axis of rotation is determined.

For a special embodiment of the invention, the control logic is able to differentiate on the basis of the measurement signals determined by the sensors whether the laboratory centrifuge is set up in such a way that the drive axis of the drive or a main axis of inertia of the rotating component of the centrifugation strand is not aligned in the direction of the gravitational acceleration vector or there is an imbalance in the rotating components of the centrifugation strand. To name only one example that does not limit the invention, on the basis of this distinction the user of the laboratory centrifuge (possibly even before the laboratory centrifuge is operated, after centrifugation has been interrupted or after centrifugation has been properly terminated) can be given feedback that either the drive axis of the drive or the main axis of inertia is not correctly aligned, so that the installation of the laboratory centrifuge on the base must be checked, or there is an imbalance in the rotating component of the centrifugation strand, which indicates that the rotor of the laboratory centrifuge is not properly loaded with the products or indicate a defect in a rotating component of the centrifugation strand.

For a further proposal of the invention, the control logic of the control unit determines an error criterion. For example, the error criterion can be present if a measured acceleration or inclination is above a threshold value or a characteristic curve that is dependent on the speed of the rotor, or if it is recognized that the rotor is not equipped with rotationally symmetrical equipment or has an imbalance or the laboratory centrifuge is not correctly aligned with the gravitational acceleration vector is. If such an error criterion is present, the control logic of the control unit generates an error message, which can be a visual error message, an acoustic error message or an error entry in an error memory, to name just a few non-limiting examples. However, it is also possible that the operation of the laboratory centrifuge is interrupted if such an error criterion is present, provided that it has already been started, or this operation is changed, which can be done, for example, by reducing the speed of the rotor or braking according to a predetermined braking curve. However, it is also possible that if the error criterion is present, the start of operation of the laboratory centrifuge, that is, the start of the drive of the rotor, is prevented.

If, within the scope of the invention, it is determined that the rotating components of the centrifugation strand have an imbalance, the control logic of the electronic control unit can be used to automatically control or regulate a position of a balancing 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. However, it is also possible that the control logic of the electronic control unit controls or regulates 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 in such a way that a Effect of an imbalance and / or an effect of incorrect alignment of the drive axis of the drive to the acceleration due to gravity is at least reduced. To name only one non-limiting example, the spring stiffness and / or damping of the spring and / or damping device can be regulated by means of the control logic. It is also possible for a compensating force to be generated in the bearing, which can then be designed as an electromagnetic bearing, or in the compensation device, which counteracts the resulting vibration of the centrifugation strand.

The invention further proposes that there be control logic in the control unit which detects a failure of at least one product and a resulting imbalance of the rotor. In this way, within the scope of the invention, it is also possible to detect an imbalance that only occurs when the laboratory centrifuge is in operation. For example, the control logic evaluates the signal from an acceleration sensor or inclination sensor at very high speeds of the laboratory centrifuge in order to be able to detect, by means of an increase in the recorded measurement signal, if the product fails at the high speeds and the associated high centripetal accelerations acting on the product, in particular, a fracture of the sample tube occurs. This can be detected, for example, on the basis of an abruptly changing amplitude of the measurement signal detected by the sensor as a result of the sudden failure of the product. While the product has a relatively small mass compared to the rotating mass of the centrifugation strand and the vibration of the centrifugation strand changes only slightly as a result of the failure of the product in the steady state, a transient transient or transient oscillation can occur in the immediate vicinity of the failure of the product Transitional behavior result, which by means of the Sensor, in particular the inclination sensor and / or the acceleration sensor, can be detected 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 perform temperature compensation for a measurement signal from 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 that is representative of the other sensors arranged on the sensor board. If a temperature curve is known for the other sensors and this is stored, for example, in a memory unit of the control unit, temperature compensation can easily take place in the control unit via the temperature measured by the temperature sensor. In this way, the accuracy of the measurement signals from the sensors can be increased.

For an embodiment according to the invention, the measurement signal of a temperature sensor is not used, or not used exclusively, for temperature compensation of the measurement signals from the sensors. Rather, the temperature measured by the temperature sensor is taken into account when determining and / or evaluating a magnitude of an imbalance in the rotating components of the centrifugation strand. Alternatively or additionally, it is possible that the temperature is taken into account when determining and / or evaluating a non-parallel alignment of the longitudinal and / or rotational axis of the centrifugation strand or a main axis of inertia of the rotating components of the centrifugation strand with respect to the acceleration of gravity. This is to be explained using the following example, which does not restrict the invention: As a result of its support via the spring and / or damping device, as explained above, the centrifugation system forms an oscillation system whose vibration behavior is due to an excitation by an imbalance of the rotating components of the centrifugation strand and / or is dependent on a resonance function or transfer function of the vibratory system due to a non-parallel alignment of the longitudinal and / or rotational axis of the centrifugation strand to the gravitational acceleration vector. This resonance or transfer function is in turn dependent on the rigidity and damping of the spring and / or damping devices. If the rigidity and / or damping of the spring and / or damping device changes as a result of a temperature change in the area of the spring and / or damping device, this leads to a change in the resonance function or transfer function. This means that the same imbalance for different temperatures or the same deviation of the alignment of the longitudinal and / or rotational axis of the centrifugation strand from the gravitational acceleration sensor can lead to different deflections, speeds or accelerations and inclinations. Conversely, in order to enable conclusions to be drawn about the alignment of the longitudinal and / or rotational axis of the centrifugation strand or the imbalance from the measurement signals of the sensors, the temperature dependence of the resonance function or transfer function and thus the stiffness and damping must be taken into account. Such a consideration can be done by modeling the temperature dependency of the resonance function or transfer function and thus converting the measurement signal depending on the resonance function or transfer function to be used at the present temperature. In the simplest case, however, such a consideration can already take place by comparing the measurement signal with a threshold value, in which case the threshold value can then be dependent on the temperature. Any desired dependency is possible, e.g. a stepped dependency of the threshold value for individual temperature ranges, a dependency according to a straight line or any smooth, kinked or jumps-shaped curve, or a functional dependency or a dependency on a characteristic map that shows the dependency on other Can take operating parameters into account. It is possible, for example, that a further operating parameter in such a characteristic map is a type of rotor used and / or different types of rotor equipment, the type or equipment being recognized automatically or being entered via a user input on the laboratory centrifuge.

In a further refinement of the invention, the control logic adjusts a service life and / or a service interval of the laboratory centrifuge, the drive or the rotor on the basis of the measurement signals measured by the sensors and / or error criteria. This embodiment is based on the knowledge that when the laboratory centrifuge is operated with suboptimal operating conditions, for example with a rotating imbalance exerting forces on the bearings and the mechanical components of the laboratory centrifuge, stress on the components of the laboratory centrifuge increases, thus reducing the service 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 centrifugation strand can arise even before the rotor starts to rotate if the products are not evenly distributed over the Scope are distributed, which can 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 has an imbalance, for example as a result of damage during a previous centrifugation or during loading. However, the rotor can also be equipped with the products in a manner that is not rotationally symmetrical, or an imbalance can result only when the laboratory centrifuge is operated when the centrifugation is started. This can be the case, for example, if there is inhomogeneous centrifugation in the samples that are arranged in the products, or if the product, in particular a sample tube or other sample container, fails. It is also possible that the laboratory centrifuge is in operation

• part of the rotor or
• an arm or holder on which one or more sample containers is / are held,

fails, which can result in an imbalance.

In the context of the invention, it is possible to determine whether the rotor is not equipped with the products in a rotationally symmetrical manner, for example by evaluating a measurement signal from an acceleration sensor, since if the rotor is not equipped with the products in a rotationally symmetrical manner, an imbalance results which then leads to a (u . U. with the rotation in the circumferential direction) leads to acceleration and oscillation of the centrifugation strand, which can be measured by means of the acceleration sensor. In this case, it is possible that a measured acceleration is compared with a threshold value or with a characteristic curve that is dependent on the speed of the rotor, with the conclusion that the rotor is not equipped with the products in a rotationally symmetrical manner when the characteristic curve or the threshold value is exceeded and / or has an imbalance. It is also possible, however, for this to be determined on the basis of a detection of an oscillating 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 little ones Rotational speeds of the rotor far below the resonance frequency of the oscillation system formed with the centrifugation strand and the spring and / or damping devices, the angular position of the circumferential deflection of the centrifugation strand corresponds approximately to the angular position of the unbalance, which has the consequence that the acceleration, which is then transferred from one to the Drive held accelerometer is measured, has a minimum. For realistic speeds of the rotor there is a phase shift between the deflection (and thus also the acceleration) and the position of the unbalance, which starts with 0 ° for frequency 0, is 90 ° at resonance frequency and is 180 ° for high speeds. To identify the angular position of the imbalance, this phase shift can be stored as a characteristic curve in the control unit and an associated memory unit. This characteristic curve is then taken into account to detect the angular position of the unbalance. The characteristic curve can also be dependent on the measured temperature.

If the laboratory centrifuge is set up at an angle and there is an angle between the longitudinal and / or rotational axis of the centrifugation strand and the gravitational acceleration vector, the rotor (and thus the products experience) an oscillating acceleration in the direction of the gravitational acceleration vector, which is undesirable because this oscillating acceleration disturb the centrifugation and the desired segregation of the sample.

To name only one non-limiting example, the acceleration of the centrifugation strand can be measured with an acceleration sensor (for example for a low drive speed of the rotor). If there is little or no acceleration of the acceleration sensor, there is neither a rotationally symmetrical assembly or imbalance of the rotor nor a deviation of the alignment of the longitudinal and / or rotation axis of the centrifugation strand compared to the alignment of the acceleration due to gravity. If, on the other hand, the acceleration sensor measures a constant constant component of the acceleration, this correlates with a constant inclination of the longitudinal and / or rotational axis of the centrifugation strand, independent of the rotation of the rotor, so that the constant component of the acceleration signal corresponds to the angle between the alignment of the longitudinal and / or or the axis of rotation of the centrifugation strand and the orientation of the acceleration due to gravity are correlated via a dependency, which, for example, can be stored in a map. If, on the other hand, an acceleration oscillating in accordance with the speed of the rotor results, the amplitude of this oscillating acceleration correlates with the imbalance. It is possible that via the (possibly temperature-dependent) resonance curve or transfer function of the oscillation system from the Amplitude of the oscillating acceleration can be inferred from the size of the imbalance. However, it is also possible that different sensors are used to differentiate between an imbalance in the centrifugation strand and the deviation of the alignment of the longitudinal and / or rotation axis of the centrifugation strand from the alignment of the acceleration due to gravity.

Advantageous further developments of the invention emerge from the patent claims, the description and the drawings. The advantages of features and of combinations of several features mentioned in the description are only exemplary and can come into effect alternatively or cumulatively without the advantages necessarily having to be achieved by embodiments according to the invention. Without changing the subject matter of the attached claims, the following applies to the disclosure content 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 to one another and their relative arrangement and operative connection. The combination of features of different embodiments of the invention or of features of different patent claims is also possible, deviating from the selected back-references of the patent claims, and is hereby suggested. This also applies to features that are shown in separate drawings or mentioned in their description. These features can also be combined with features of different patent claims. Features listed in the claims for further embodiments of the invention can also be omitted.

The number of features mentioned in the claims and the description are to be understood in such a way that precisely this number or a greater number than the stated number is present without the need for the explicit use of the adverb "at least". Thus, if, for example, an inclination sensor is mentioned, this is to be understood in such a way that precisely one inclination sensor, two inclination sensors or more inclination sensors are present. These characteristics can be supplemented by other characteristics or be the only characteristics that make up the product in question.

The reference signs contained in the claims do not represent a restriction of the scope of the subject matter protected by the claims. They only serve the 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 is further explained and described with reference to preferred exemplary embodiments shown in the figures.

Fig. 1

shows in a horizontal view components of a laboratory centrifuge, namely a centrifugation strand, which is supported by spring and / or damping devices relative to a housing, the drive of the centrifugation strand having a sensor board equipped with several sensors.

Fig. 2

shows the sensor board in a mounting ring in a three-dimensional view obliquely from above.

Fig. 3

shows the arrangement of sensors and an electronic control unit on a sensor board in a highly schematic manner.

FIGURE DESCRIPTION

Fig. 1 shows in a horizontal view components of a laboratory centrifuge 1. A centrifugation strand 2 has an electric drive 3, a rotor 4 and a drive and / or rotor shaft 5, via which the drive 3 rotates the rotor 4 about a longitudinal and / or rotational axis 6 can move 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 supported on a housing 8 of the laboratory centrifuge 1 in a resilient and damping manner via spring and / or damping devices 7a, 7b. The centrifugation strand 2 and the spring and / or damping devices 7 form an oscillation system 9. In the oscillation system 9, the centrifugation strand 2 forms the oscillating mass, while the rigidity and the damping of the oscillation system 9 are predetermined by the spring and / or damping devices 7. The spring and / or damping devices 7a, 7b preferably enable deflections and thus possibly oscillating degrees of freedom of the oscillation 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 centrifugation strand 2 transversely to the longitudinal and / or axis of rotation 6 and
3. c) Inclination of the longitudinal and / or rotational axis 6 by an angle with respect 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 area of the bottom of the laboratory centrifuge 1 and under certain circumstances are arranged in a room 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 plate or support of the housing 8 of the laboratory centrifuge 1. The opposite foot point 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 can have suitable flanges 10a, 10b to which the spring and / or damping devices 7a, 7b are attached. In the ideal case, the centrifugation strand 2 does not have an imbalance with regard to the longitudinal and / or rotational axis 6. However, an imbalance can result, for example, from defects or damage to the drive 3 or the rotor 4 of the centrifugation strand 2, from damage to at least one product, or from improper or non-rotationally symmetrical loading of the rotor 4 with products.

For centrifugation, the rotor 4 of the laboratory centrifuge 1 is equipped with products, and for this purpose the rotor 4 can be designed as a fixed-angle swing-out rotor or a drum rotor. Here, the products are to be arranged as rotationally symmetrical as possible on the rotor 4 and / or distributed over the circumference of the rotor 4 in such a way that there is no unbalance between the rotor 4 and the products.

In the event of an imbalance or an eccentric arrangement of the center of gravity of the centrifugation strand 2 during operation of the laboratory centrifuge 1, the longitudinal and / or rotation axis 6 of the centrifugation strand 2 may change as a result of the elastic support of the centrifugation strand 2. For low 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 rotation axis 6 revolves around a conical surface at the speed of the rotor.

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

On the side of the drive 3 facing a base of the housing 8 or on the side of the drive 3 facing away from the rotor 4, a sensor circuit board 12 is held on a housing 11 of the drive 3. For the exemplary embodiment shown here, this is done via a receiving and fastening unit 13 screwed to the housing 11 of the drive 3. A cable harness 14 extends from the sensor circuit board 12, which can be of any design, multi-core, unidirectional or bidirectional, from the receiving and fastening unit 13 out, which is done here in the horizontal direction. At the end facing away from the sensor circuit board 12, the wiring harness 14 has a plug 15.

Fig. 2 shows a three-dimensional view of the sensor board 12 with the wiring harness 14 extending therefrom in the receiving and fastening unit 13. The receiving and fastening unit 13 is designed here as an annular disk 17 and has through bores 18a, 18b, 18c distributed over the circumference. Furthermore, on the side facing the housing 11 of the drive 3, the annular disk 17 has a radially continuous groove 19 through which the cable loom 14 extends. Finally, on the radially inner side, in partial circumferential areas, the ring has open-edged recesses 20a, 20b, 20c (as well as a further recess covered by the wiring harness 14), which are arranged on the ring disk 17 in accordance with the outer contour of the sensor board 12 and their geometry in such a way is that in these recesses 20a, 20b, 20c corners, the sensor board 12 is received with a play, a play 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 disk 17, with the sensor board 12 is then caught between the bottom of the recesses 20 and the housing 11 of the drive 3 by screwing the annular disk 17 onto the housing 11 of the drive 3. But it is also possible that the sensor board 12 is additionally attached to the annular disk 17, which can be achieved by any fastening means such as an adhesive, screwing, clipping and the like. Ä. Can take place. For the in Fig. 2 In the illustrated embodiment, the recesses 20, which are open radially inward, have an angular cross-section, the angular cross-sections of the recesses 20 complementing each other to form a rectangle, the dimensions of which correspond to the outer dimensions of the sensor board 12 with a play, a loose fit, a transition fit or an interference fit.

The sensor circuit board 12 is preferably equipped on the side facing the housing 11 of the drive 3. The thickness of the annular disk 17 and the depth of the recesses 20 are selected such that the electronic and electrical components of the sensor board 12 are arranged with a small gap from the housing 11 of the drive 3. For the illustrated embodiment, the sensor board 12 is ventilated from the bottom area of the laboratory centrifuge 1 through spaces 21a, 21b, 21c, 21d.

Fig. 3 shows, in a highly schematic manner, a possible assembly 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 connector 28, An electronic control unit 29 and a 9-axis sensor 30 can be connected to which the wiring harness 14 can be connected via a corresponding plug.

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

It is also possible, however, for the magnetic field sensor 27 or one of the inclination sensors 22, 23 to detect the magnetic field of a permanent magnet 31. The permanent magnet 31 is attached to the housing 8 of the laboratory centrifuge 1. In the event that, as in Fig. 1 shown, the magnetic field sensor 27 with the sensor board 12 is arranged in the bottom area of the laboratory centrifuge 1 on the housing 11 of the drive 3, the permanent magnet 31 is also arranged in the bottom area of the laboratory centrifuge 1. For example, the permanent magnet 31 is attached to a base plate or a base-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 alignment 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 with respect to the magnetic field of the permanent magnet 31 and thus the inclination of the longitudinal and / or rotational axis 6 with respect to the housing 8 is detected.

Within the scope of the invention it can be determined by means of the control unit 29 on the basis of the measurement signals whether the axis of rotation of the rotor 4 corresponds to the main axis of inertia of the rotor 4 with the products held thereon. Deviations from this are detected by the control logic as an imbalance, which leads to vibrations. A qualitative and / or quantitative detection of the imbalance can take place here. If an existing imbalance is detected, the drive 3 is braked in a controlled manner. An emergency braking procedure can be initiated, in which case an interaction with the user can take place via the output of an optical or acoustic error message, for example, so that there is a risk as a result of the imbalance can be recognized by the user or a higher-level machine.

It is possible for a lid of the laboratory centrifuge 1 to be released to enable the laboratory centrifuge 1 to be opened with the detection of an imbalance only when the rotor 4 is at a standstill.

It is also possible for the user to be warned after the rotor 4 has been loaded with the products before the rotor 4 is driven, if an imbalance could arise during operation. This can be the case with a missing product, a product in the wrong place, or an uneven loading of the rotor 4 with the products.

Another possible cause of the occurrence of an imbalance can be a bent, tilted, tilted or insufficient fastening of the rotor 4.

It is also possible for the measured measurement signals or a result of the evaluation thereof to be used as process parameters. For example, in the case of an automatically loaded and unloaded laboratory centrifuge 1 or also a manually loaded and unloaded laboratory centrifuge 1, it is possible to monitor that for different cycles of the laboratory centrifuge 1 with several sets of samples with the desired identical equipment, measured values or evaluation results are within a specified tolerance range must surrender. Here, for example, amplitudes, Signal curves, rectified and integrated signal curves, etc. Ä. can be compared with specified tolerance ranges. It is also possible to monitor whether the result of the evaluation by the control unit for a determined imbalance or an inclination of a longitudinal and / or rotational axis of the centrifugation strand 2 lies within a tolerance range. If a measurement signal or a result of the evaluation lies outside the tolerance range, an error message can be output or an error entry can be made. Under certain circumstances, a changed assembly (e.g. a different rotor and / or other products attached to the rotor or a changed number of products attached to the rotor) can be detected without this necessarily leading to a threshold value for a permissible imbalance being exceeded . In this case, information can be given to the user or a higher-level automated machine that the equipment should be checked.

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

The measurement signals can be evaluated in the time domain or in the frequency domain. A coordinate transformation between rotor and drive movements can also take place here. Other device parameters such as the rotor speed, the power consumption of the drive or RZB can also be included in the evaluation.

An evaluation can take place on the sensor circuit 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 set as the threshold value for a measured inclination or a measured acceleration, a dynamic threshold value is calculated and / or the measured inclination or the measured acceleration is integrated over time and switched off when a limit value is exceeded.

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

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 when the rotor 4 is slowly rotated, this inclination is based on a non-horizontal setup of the laboratory centrifuge 1. If, however, this inclination changes with the rotation of the rotor 4, the non-rotationally symmetrical equipment or an imbalance of the rotor 4 is responsible for this . A corresponding error message can then be generated.

The individual sensors or the sensor circuit board 12 can already be equipped with an AD converter, or an AD conversion takes place after the measurement signals have been transmitted via the wiring harness 14.

The measurement signals are preferably evaluated, at least in part, using a Fast Fourier Transformation (FFT). Under certain circumstances, in the result of the FFT, the amplitude of the signal increases in the case of upper and / or lower waves to the base frequency dependent on the speed of the rotor 4, so that based on the spectral lines of the FFT for the upper and / or lower waves, there is also an imbalance and under certain circumstances the amount can also be deduced. It is also possible for a direct component of the recorded signals to be separated from an alternating component via an FFT.

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

It is also possible that the control unit 29 arranged on the sensor board 12 is already used to prepare the measurement signals from the sensors, which can be done, for example, in such a way that for different rotors 4 and sensor boards 12 an adaptation to the different types of rotors and those used Sensors through the control unit 29 takes place and then standardized output signals can then be transmitted via the line strand 14, 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, centrifugation can be prevented or an initiated centrifugation can be terminated and / or information can be given to the user.
2. b) After an undesired inclination has been detected at a standstill, a corresponding message can be sent to the user and / or the drive of the rotor can be deactivated.
3. c) A corresponding entry can be made in a memory (of the rotor or the laboratory centrifuge) in order to document the history of the centrifugation and / or the rotor.
4. d) If a defect occurs, in particular an engine defect, 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 for suitable measures to be taken to reduce the effects of any imbalance. For example, magnetic bearings can be adapted to support the rotor.
7. g) An interaction with a lid lock is possible so that, for example, opening of the lid is prevented if an imbalance is detected and the rotor in the laboratory centrifuge is still turning.
8. h) If there is a sudden change in the acceleration signal or a characteristic parameter during operation of the rotor, this is evaluated as an indication, in particular, of a failure of a container, for example a break in a tube. The background here is that in the event of an imbalance of, for example, 100 g during operation, emergency braking can only be initiated using known laboratory centrifuges when this is already too late, so that the laboratory centrifuge can be destroyed. According to the invention, a failure of the container can be detected relatively early in the event of a container failure, that is to say when there is a small imbalance that occurs, so that emergency braking can be detected earlier.

In contrast to the embodiment shown, the sensor circuit board 12 can also be arranged in a side area of the housing 11 of the drive 3 or even be integrated into the drive 3.

If, within the scope of the invention, an acceleration of the drive or an alignment of the drive is mentioned, this preferably relates to an acceleration or alignment of the housing of the drive.

For one embodiment of the invention, the measurement signals are evaluated, in particular to determine 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 rpm or Above 4,000 rpm up to the maximum speed of the laboratory centrifuge 1, an evaluation takes place based on the measurement signal of an inclination sensor, which can in particular detect a transient transient response in the event of a broken tube, even at the high speeds mentioned.

REFERENCE LIST

1

Laboratory centrifuge

2

Centrifugation line

3

drive

4th

rotor

5

Drive and / or rotor shaft

6th

Longitudinal and / or rotational axis

7th

Spring and / or damping device

8th

Housing laboratory centrifuge

9

Vibration system

10

flange

11

Housing drive

12

Sensor board

13

Mounting and fastening unit

14th

Wiring harness

15th

plug

16

Gravitational acceleration vector

17th

Washer

18th

Through hole

19th

Groove

20th

Recess

21st

Space

22nd

first position and / or inclination sensor

23

second position and / or inclination sensor

24

first accelerometer

25th

second accelerometer

26th

Temperature sensor

27

Magnetic field sensor

28

Connectors

29

Control unit

30th

9-axis sensor

31

Permanent magnet

Claims (14)

1. Laboratory centrifuge (1) with a centrifugation drivetrain (2) comprising a drive (3) and a rotor (4) driven by the drive (3), the centrifugation drivetrain (2) being supported by at least one spring and/or damping device (7) on a housing (8), characterised in that at least one inclination sensor (22, 23) is provided which senses an orientation of a longitudinal and/or rotational axis (6) of the centrifugation drivetrain (2), the inclination sensor being a gyroscopic sensor and the gyroscopic sensor being held by a housing (11) of the centrifugation drivetrain (2).
2. Laboratory centrifuge (1) of claim 1, characterised in that two inclination sensors are provided,

   a) one inclination sensor being a gyroscopic sensor which is held by the housing of the centrifugation drivetrain (2) and

   b) one inclination sensor comprising a magnetic field sensor and a permanent magnet generating a magnetic field.
3. Laboratory centrifuge (1) of one of the preceding claims, characterised in that

   a) at least two acceleration sensors (24, 25) are provided which sense an acceleration of the drive (3) with differing sensitivities and/or in different frequency regions and/or

   b) at least two inclination sensors (22) are provided which sense an inclination of the drive (2) with different sensitivities and/or in different frequency regions and/or

   c) at least one sensor (27) is provided which senses the orientation of the centrifugation drivetrain (2) relative to a terrestrial magnetic field or relative to a vector (16) of the acceleration due to gravity and/or

   d) at least one sensor is provided which senses a rotational angle, an angular velocity or an angular acceleration of a driving shaft (5) of the drive (3),

   e) a temperature sensor (26) and/or

   f) a sensor (30) comprising 9 axes

   are/is provided.
4. Laboratory centrifuge (1) of one of the preceding claims, characterised in that the sensors are at least partially arranged on a sensor circuit board (12).
5. Laboratory centrifuge (1) of one of the preceding claims, characterised in that the sensors are at least partially and/or the sensor circuit board (12) is arranged on the side of the centrifugation drivetrain (2) or of the drive (3) remote from the rotor (4).
6. Laboratory centrifuge (1) of one of the preceding claims, characterised in that an electronic control unit (29) is provided which processes the measurement signal or the measurement signals of the sensors.
7. Laboratory centrifuge (1) of claim 6, characterised in that the electronic control unit (29) comprises control logic which

   a) determines if the laboratory centrifuge (1) has been positioned in a way such that the driving axis of the drive (3) or a main inertial axis of the rotating components of the centrifugation drivetrain (2) has an orientation as the orientation of the vector (16) of the acceleration due to gravity and/or

   b) determines an unbalanced mass of the rotating components of the centrifugation drivetrain.
8. Laboratory centrifuge (1) of claim 6 or 7, characterised in that the electronic control unit (29) comprises control logic which on the basis of the measurement signals determined by the sensors distinguishes if

   a) the laboratory centrifuge (1) has been positioned in a way such that the driving axis of the drive (3) or a main inertial axis of the rotating components of the centrifugation drivetrain (2) does not have an orientation as the orientation of the vector (16) of the acceleration due to gravity or

   b) there is an unbalanced mass of the rotating components of the centrifugation drivetrain (2).
9. Laboratory centrifuge (1) of one of claims 6 to 8, characterised in that the electronic control unit (29) comprises control logic which in the case of the presence of an error criterion

   a) generates an error message,

   b) changes or interrupts the operation of the laboratory centrifuge (1) and/or

   c) disables the operation of the laboratory centrifuge (1).
10. Laboratory centrifuge (1) of one of claims 6 to 9, characterised in that the electronic control unit (29) comprises control logic which

    a) controls a position of a compensation mass for compensating an unbalanced mass of the rotating components of the centrifugation drivetrain and/or

    b) controls at least one bearing, at least one compensating device and/or at least one spring and/or damping device (7) in a way such that an effect of an unbalanced mass of the rotating components of the centrifugation drivetrain and/or a non-parallel alignment of the driving axis of the drive (3) or of a main inertial axis of the rotating components of the centrifugation drivetrain (2) with the acceleration due to gravity is at least reduced.
11. Laboratory centrifuge (1) of one of claims 6 to 10, characterised in that the electronic control unit (29) comprises control logic which senses a failure of at least one product and an unbalanced mass of the rotor (4) resulting from this failure.
12. Laboratory centrifuge (1) of one of claims 6 to 11, characterised in that the electronic control unit (29) comprises control logic which on the basis of a temperature measured by a temperature sensor (26) performs a temperature compensation of a measurement signal of another sensor.
13. Laboratory centrifuge (1) of one of claims 6 to 12, characterised in that the electronic control unit (29) comprises control logic which

    a) for the determination and/or the evaluation of the effect or value of an unbalanced mass of the rotating components of the centrifugation drivetrain and/or

    b) for a determination and/or evaluation of a non-parallel alignment of the longitudinal and/or rotational axis of the centrifugation drivetrain (2) or of a main inertial axis of the rotating components of the centrifugation drivetrain (2) with the acceleration due to gravity

    considers the temperature measured by a temperature sensor.
14. Laboratory centrifuge (1) of one of claims 6 to 13, characterised in that the electronic control unit (29) comprises control logic which on the basis of

    a) the measurement signals measured by the sensors,

    b) the evaluation of the measurement signals and/or

    c) error criteria

    adapts a lifetime and/or a maintenance interval of the laboratory centrifuge (1), of the drive (3) or of the rotor (4).

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