Centrifuge, centrifuge operation method and computer readable medium

Abstract

The invention relates to a centrifuge (19), in particular a flow-through centrifuge, a biotechnological centrifuge or a blood centrifuge. The centrifuge (19) has a refrigerant circuit (1). According to the invention, the output of the adjustable compressor (4) is connected to the input of the evaporator (2) via a bypass line (15) having a valve (20) arranged therein. In the normal operating mode, the centrifugal kettle (3) is cooled only by adjusting the compressor (4) and the expansion device (6) when the valve (20) is closed. Instead, if the tolerance range of the target temperature in the centrifugal vessel (3) is insufficient, the valve (20) is opened to effect heating, thereby restoring the temperature in the centrifugal vessel (3) to the tolerance range.

Description

Technical Field

[0001] The invention relates to a centrifuge.

[0002] The centrifuge is preferably a flow-through centrifuge in which at least one medium is at least temporarily supplied to the centrifuge chamber and / or discharged from the centrifuge chamber during the rotation of the centrifuge chamber. The at least one medium is in particular a medium to be centrifuged, a flushing liquid, a buffer solution or a modified medium extracted from the centrifuge medium or a precipitate in the centrifuge chamber. To name a few examples that do not limit the present invention: the flow-through centrifuge can be a blood centrifuge in which the medium to be centrifuged is blood and the modified medium or precipitate extracted is blood cells or blood particles; or, the flow-through centrifuge can also be a centrifuge for obtaining cells contained in the medium, microcarriers or other particles contained in the medium. The centrifuged medium may also not be a pure liquid, but a solution or suspension with particles such as cells, cell fragments or microparticles. For example, this type of flow-through centrifuge is used in the production of biopharmaceuticals or biotechnological products in biopharmaceutical companies or bioprocessing applications. For example, a flow-through centrifuge can be used to obtain and / or clarify cells or microcarriers, wherein the cells obtained thereby can be used for cell therapy. Other fields of application include (but are not limited to) the production of vaccines or the processing of blood to obtain blood cells. For example, Sartorius AG (address: Otto-Brenner-Straße 20, 37079 Göttingen, Germany) and its affiliated companies market such flow-through centrifuges under the trademark "Ksep" (registered trademark). See also:

[0003] www.sartorius.com / en / products / process-filtration / cell-harvesting / ksep-systems (accessed on 28 June 2022).

[0004] The rotor of this flow-through centrifuge has in particular four centrifugal chambers, which can be designed as bags held on the rotor body and evenly distributed on the circumference. The centrifugal chambers are at a certain radial distance from the axis of rotation of the rotor. The first connecting line leads to the centrifugal chamber radially on the inside, while the second connecting line leads to the centrifugal chamber radially on the outside. In the first operating phase, the first medium (e.g. blood) is supplied to the centrifugal chamber through the second connecting line, while the centrifugal chamber rotates with the rotor. In the centrifugal chamber, the particles contained in the medium are deposited radially on the outside due to centrifugal action, while the residual medium (i.e. the medium supplied radially on the outside with the particles squeezed radially outward) is discharged radially from the centrifugal chamber radially on the inside through the first connecting line. Therefore, in this first operating phase, the first connecting line is the discharge line, and the second connecting line is the supply line. As the operation continues, the proportion of particles in the centrifugal chamber and their concentration increase continuously until the centrifugal chamber is substantially or completely filled with particles. In the subsequent optional second operating phase, the particles in the centrifugal chamber are cleaned. For this purpose, a washing or buffer solution enters the centrifugal chamber through the second connecting line. The washing or buffer solution rinses the centrifugal chamber and is discharged radially inwardly through the first connecting pipe. In this operation phase, the centrifugal chamber also rotates with the rotor to prevent particles from leaving the centrifugal chamber through the first connecting pipe together with the washing or buffer solution under the action of centrifugal force. During the second operation phase, the first connecting pipeline is also used as a discharge pipeline for the washing or buffer solution, and the first connecting pipeline is used as a supply pipeline for the washing or buffer solution. In addition, in the subsequent third operation phase, the centrifugal chamber continues to rotate with the rotor. In this third operation phase, the flow direction flowing through the centrifugal chamber is opposite, and particles are removed from the centrifugal chamber through the second connecting pipeline, while the washing or buffer solution is supplemented by the first connecting pipeline. When all particles are removed from the centrifugal chamber, the third operation phase ends. This is followed by further successive cycles of the above-mentioned three operation phases.

[0005] Such flow-through centrifuges that can be applied to the present invention are disclosed by EP3936601A1, EP2310486B1, EP2485846B1, US4216770, US4419089, US4389206, and US5665048.

[0006] The centrifuge according to the invention can have a horizontal axis of rotation, so that during the centrifugation process, the medium (e.g. blood, washing fluid and particles) can be exchanged in the region of the rotating rotor axis. A flow-through centrifuge designed in this way can be, for example, a blood centrifuge or the like, in which blood is centrifuged as the medium.

[0007] Furthermore, the invention relates to a method for operating such a centrifuge and a computer-readable medium. Background Art

[0008] EP2814617B1 provides the following information on the prior art for cooling laboratory centrifuges:

[0009] During centrifugation, especially in laboratory centrifuges with very high rotation speeds, the centrifuge rotor generates heat in the centrifuge vessel during rotation due to air friction and the introduction of electrical power losses. Since the centrifuge vessel is closed by a lid to prevent the centrifuge material from escaping, the introduced heat cannot be easily discharged and leads to an increase in the temperature of the centrifuge material. However, this temperature increase is undesirable because it can lead to the destruction of the centrifuged sample or its unusability. Normally, the sample must be kept at a defined temperature, such as 4°C, 22°C or 37°C, depending on the application. Therefore, in the past, some precautions have been taken to avoid an increase in the temperature of the centrifuged material, in which indirect cooling is usually used. In this indirect cooling, the rotor is usually enclosed in the centrifuge vessel under the centrifuge lid and no cooling channels or similar devices are provided. Therefore, the air circulates only in the centrifuge vessel. Now, cooling is achieved by a second medium, which is guided over the outside of the centrifuge vessel or in the centrifuge vessel wall. For this purpose, a refrigerant circuit with a compressor, pipes and a heat exchanger is usually provided, by means of which a special refrigerant is guided through the centrifugal reactor through pipes (which are, for example, spirally attached to the centrifugal reactor, i.e., the side walls and the bottom of the reactor) to remove heat. Unlike the "coolant" used, for example, in the cooling water circuit of an automobile, the refrigerant undergoes a phase change when passing through the refrigerant circuit, i.e., usually from a liquid to a gaseous state. With this refrigerant, it is also possible to adjust the temperature of a coolant whose temperature is lower than the ambient temperature. With the help of the refrigerant circuit, the sample material can also be cooled to a temperature lower than the ambient air temperature. Laboratory centrifuges of this type are disclosed, for example, by DE3818584A1 or JP2011-255330A. Such a refrigerant circuit 1 has an evaporator 2 (which usually surrounds the centrifugal reactor 3 in an annular manner), a compressor 4, a liquefier 5 and an expansion device 6 (see FIG. 1 ). The expansion device 6 is designed for the highest possible load case, i.e. the maximum rotational speed of the centrifuge rotor (not shown), wherein, as is already known, the expansion device 6 (pressure compensation element between the high-pressure section and the low-pressure section of the refrigerant circuit 1 when the compressor 4 is stopped) is designed as a capillary tube or a thermostatic injection valve 7 (also referred to as "TEV"). In conjunction with a pressure-controlled temperature sensor 8 downstream of the evaporator 3, the thermostatic injection valve 7 is used to automatically increase or throttle the refrigerant flow in the refrigerant circuit 1 at the evaporator inlet VE as a function of the detected temperature. For this purpose, it is necessary to superheat the refrigerant at the evaporator outlet VA, thereby generating an overpressure, which is directly directed to the spring 9 of the thermostatic injection valve 7 in order to actuate the thermostatic injection valve. More precisely, a certain temperature at the evaporator outlet VA. The sensor 10 of the thermostatic injection valve 7 is fixed to the evaporator outlet VA, which also contains a refrigerant that can correspond to the refrigerant of the refrigerant circuit 1. Due to the temperature at the evaporator outlet VA, the refrigerant has a corresponding pressure, which acts on the thermostatic injection valve 7 and the reaction force of the spring 9, thereby opening or closing the thermostatic injection valve 7.Other load situations can be partially regulated by a further regulating element, which in this case is a frequency or speed regulated compressor 4, but usually not precisely. Since the refrigerant must be superheated in order for the thermostatic injection valve 7 to function, the evaporator power cannot be fully utilized, wherein only about 95% of the evaporator surface can be used. Due to the required superheating, there is a temperature difference of about 7 K between the evaporator inlet VE and the evaporator outlet VA. Another significant disadvantage of this known refrigerant circuit 1 in a centrifuge is that the compressor 4 can only be controlled relatively imprecisely and within certain limits in terms of its power, so that in various partial load and low load situations, the compressor 4 may have to be completely shut down. However, this is not always possible, because the compressor 4 usually has a minimum running time to ensure the internal oil circuit. On the other hand, due to the higher heating of the drive motor of the compressor 4 during startup and the necessary pressure compensation or pressure difference reduction between the high-pressure section and the low-pressure section, such compressors 4 also have a certain minimum idle time, so that the regulation possibilities by the compressor 4 are severely limited, especially in the lower power range. Another disadvantage is that vibrations occur when the compressor 4 of the refrigerant circuit 1 is started or stopped. These vibrations can affect the centrifuge's operating performance, increase the back-mixing rate in the rotor after the centrifuge is shut down, and have an impact on adjacent laboratory equipment, etc. Finally, frequent switching on and off of the compressor 4 can shorten its service life.

[0010] In this context, EP2814617B1 proposes a refrigerant circuit 1 (see FIG. 2 ), in which the expansion device 6 is designed as a throttling device that can be electronically controlled continuously or discretely (it can also be designed as an electronic injection valve 11). Temperature sensors 12, 13, and 14 detect the refrigerant temperature at the inlet VE of the centrifugal kettle 3, the actual temperature in the centrifugal kettle 3, and the temperature at the outlet VA of the centrifugal kettle 3. The temperature signals of the temperature sensors 12, 13, and 14, the rated temperature of the centrifugal kettle 3, and the tolerance range (especially ±5K) of the actual temperature of the centrifugal kettle 3 relative to the rated temperature are supplied to an electronic control unit. The electronic control unit controls the electronic injection valve 11 and the controllable compressor 4 for temperature regulation. The bypass line 15 connects the connecting line 16 between the electronic injection valve 11 and the evaporator 2 to the connecting line 17 between the compressor 4 outlet and the evaporator 2. An electronic injection valve 18 is not known in the bypass line 15. The electronic control unit can also control the electronic injection valve 18. According to EP2814617B1, the switch between coarse adjustment and fine adjustment is carried out as follows: when the laboratory centrifuge is started, the coarse adjustment is used until the actual temperature is within the tolerance range within a predetermined time. Then the switch is made and the fine adjustment is basically maintained during the subsequent operation. Only when the actual temperature exceeds the tolerance range despite the fine adjustment, the coarse adjustment is restored. During the coarse adjustment, only the compressor 4 is adjusted, and the electronically controlled injection valves 11 and 18 are not adjusted. On the contrary, during the fine adjustment, the power of the compressor 4 remains unchanged. Then the adjustment is made by adjusting the electronic injection valve 11. During the fine adjustment, the electronic injection valve 11 is adjusted according to three different criteria. First, when the trend of the actual temperature of the centrifugal tank 3 decreases [or increases] in the predetermined trend period, the electronic injection valve 11 is adjusted downward [or upward], thereby reducing [or increasing] the flow rate of the refrigerant. When the refrigerant temperature at the inlet VE of the evaporator 2 is less than the predetermined temperature threshold at the inlet VE of the evaporator 2, the opening of the electronic injection valve 11 is also triggered, wherein the opening is so long maintained until the temperature is greater than the predetermined temperature threshold again. In this way, the compressor 4 should be prevented from operating in the vacuum range. Finally, the temperature difference between the outlet of the compressor VA and the inlet of the compressor VE is also monitored. This temperature difference should be between 0 K and 1 K to keep the load rate of the evaporator 2 at a maximum and prevent liquid refrigerant from entering the compressor 4. If the difference is insufficient, the electronic injection valve 11 is further closed and / or the compressor frequency is reduced.

[0011] JP2010-008022A discloses a refrigerant circuit for a centrifuge, in which, in a normal operating mode without the possibility of regulation, the refrigerant flows from the compressor via a liquefier, a dryer and two capillaries connected in series to an evaporator. If the cooling of the centrifugal kettle in this way results in too low a temperature, the bypass valve is moved to the open position so that the refrigerant also flows from the compressor outlet via the downstream capillary to the evaporator via the bypass line, wherein the refrigerant flowing through the bypass line bypasses the liquefier and the upstream capillary. The diameter of the upstream capillary is selected to be smaller than the diameter of the downstream capillary in order to predetermine the refrigerant flow in the parallel line branches when the solenoid valve is open.

[0012] EP0295377A2 discloses a refrigerant circuit for a centrifuge, in which the outlet of the compressor is connected to the cooling coil of the centrifuge vessel via a parallel connection of a hot pipe section and a cold pipe section, in which the liquefier is arranged. Pulse width modulation valves are arranged in the hot pipe section and the cold pipe section, which valves operate in push-pull mode. Here, the heat supplied to the cooling coil depends on the pulse width, which is adjusted according to the measured temperature in the centrifuge vessel. Summary of the invention

[0013] The object of the present invention is to improve the structure of a centrifuge and its operating method so that it can react to an unexpected drop in temperature in a centrifuge vessel. In addition, another object of the present invention is to provide a computer-readable medium for a correspondingly improved method, which has a control logic.

[0014] Solution

[0015] According to the invention, the object of the invention is achieved by the features of the independent claim. Further preferred embodiments of the invention can be derived from the dependent patent claims.

[0016] Description of the invention

[0017] The invention relates to a centrifuge having a centrifuge tank. The centrifuge also has a refrigerant circuit in which a refrigerant circulates, preferably undergoing a phase change in the refrigerant circuit. The refrigerant circuit is used to cool the centrifuge tank in order to ensure that a target temperature in the centrifuge tank is within a tolerance range.

[0018] In the centrifuge, the temperature in the centrifuge tank is detected (directly or indirectly) by a temperature sensor. To name a few examples, which do not limit the invention: the temperature sensor can be arranged in the wall of the centrifuge tank or on the cover of the centrifuge, in particular as close as possible to the centrifuge chamber of the centrifuge tank or directly adjacent to it. However, it is also possible to integrate the temperature sensor into the rotor or the centrifuge container, which is held on the rotor for centrifuging the material (see also the disclosure in EP3560592A1).

[0019] The refrigerant circuit used in the present invention has a compressor whose speed, frequency and / or power can be adjusted. In addition, the refrigerant circuit also has a liquefier, in particular a condenser. An adjustable expansion device is also arranged in the refrigerant circuit. The refrigerant circuit also has an evaporator that delivers cold to the centrifugal kettle. For example, the evaporator can surround the centrifugal kettle with a pipeline, or the pipeline can also be integrated into the wall of the centrifugal kettle. In the refrigerant circuit, the adjustable expansion device is preferably arranged upstream of the evaporator. With the help of the adjustable expansion device, the control of the refrigerant flow rate and / or the expansion of the refrigerant can be affected, thereby affecting the configuration of the pressure and temperature conditions of the refrigerant in the low-pressure section and the evaporator area. The adjustable expansion device can be designed to be passive (passive), in particular, it can be a thermostatic injection valve, or it can also be designed to be active (active), in particular in the form of an electronically controlled throttling device or other electronically controlled expansion devices.

[0020] According to the invention, the connection line from the compressor to the liquefier is connected to the connection line between the expansion device and the evaporator via a bypass line. The bypass line preferably bridges the liquefier and the adjustable expansion device. The bypass line can establish a connection between the high-pressure section and the low-pressure section of the refrigerant circuit. In order to control this connection, an electronic control valve is arranged in the bypass line to control the flow through the bypass line.

[0021] The invention proposes to provide an electronic control device with a control logic in the centrifuge. The control logic can monitor the difference between a predetermined target temperature in the centrifuge tank and the temperature detected by the temperature sensor (i.e. the actual temperature in the centrifuge tank). If the difference is greater than a predetermined threshold value, the control unit activates a valve arranged in the bypass line, thereby increasing the flow through the bypass line. This is preferably the case if the control unit has controlled the minimum power of the compressor and / or the control unit has controlled the expansion device so that the evaporator absorbs heat to the maximum extent. Therefore, when conventional measures for preventing the temperature in the centrifuge tank from decreasing have been exhausted, but the temperature is still below the target temperature by the threshold value (without the measures of the invention, it may be necessary to shut down the compressor), it is preferred to control the valve to increase the flow through the bypass line. In this case, the control of the valve causes more refrigerant to flow from the high-pressure side to the low-pressure side at the inlet of the evaporator. This increases the amount of hotter refrigerant on the high-pressure side that is mixed into the low-pressure side at the inlet of the evaporator, which ultimately leads to a reduction in the heat dissipated from the centrifuge tank by the evaporator. In this way, a strong drop in temperature in the centrifuge tank can be compensated, which also makes it unnecessary to shut down the compressor or to further or strongly reduce the compressor power.

[0022] In principle, there are many options for the valve arranged in the bypass line in terms of structural type (such as seat valve, slide valve, etc.), operating position (continuous operating position; any number of discrete operating positions) and control options, as long as the valve can be controlled by an electronic control unit. All suitable valves known in the prior art can be used. For one suggestion of the present invention, the valve is designed as a 2 / 2 solenoid valve, which has a larger opening position and a smaller opening position. For example, the smaller opening position may be a closed position, and the larger opening position may be a conducting position. In this case, the valve is basically in the closed position, in which the bypass line is closed. Only when the difference between the target temperature in the centrifugal reactor and the temperature detected by the temperature sensor is greater than a threshold value, the control unit will control the 2 / 2 solenoid valve to the open position. In this case, the 2 / 2 solenoid valve can be brought into the closed position by the control unit without electrical excitation, and electrical excitation can be performed for switching to the open position. However, the valve can also be designed in reverse so that it is switched to the closed position by electrical excitation. In this case, the stable position of the valve can be fixed by a spring, and the stable position can only be left by electrical excitation. For another embodiment, the valve can be designed as a bistable valve, which can maintain a determined open position on the one hand and a closed position on the other hand without valve actuation. Electrical actuation of the valve is only required when changing the valve position in both directions.

[0023] There are many possibilities for the criterion of controlling the 2 / 2 electromagnetic valve to the open position. For example, the 2 / 2 electromagnetic valve can be controlled to the conduction position for such a long time until the difference between the target temperature in the centrifugal kettle and the temperature detected by the temperature sensor is lower than the threshold value or any other temperature related to the target temperature again. In a particularly simple design of the present invention, the control logic controls the 2 / 2 electromagnetic valve from the cut-off position to the open position for a predetermined time span. Here, the predetermined time span may depend on the operating parameters of the centrifuge, which may be related to the rotating speed of the centrifuge, the ambient temperature of the centrifuge, the material to be centrifuged at present and / or the rotor type used in the centrifuge, just to name a few, but not limiting the present invention. In addition, during the operation of the centrifuge and also in a large number of operating cycles, the time span of the valve being controlled to the conduction position by the control logic can also be learned.

[0024] Within the scope of the invention, any expansion device can be used, thus it can also be an electronically controlled expansion valve or an electronically controlled throttling device. In a particularly simple design of the invention, within the scope of the invention, a passive thermostatic injection valve is used as expansion device.

[0025] In the centrifuge according to the invention, compressors of any design can be used. Preferably, rolling piston compressors (or rotary piston compressors) are used, the operation of which has proven to be very advantageous in terms of eliminating undesirable vibrations on the one hand, and in terms of operating environmentally compatible refrigerants on the other hand.

[0026] In one solution of the invention, a valve with a plurality of different opening cross sections can be used instead of designing the valve as a 2 / 2 solenoid valve. In this case, the valve can have a plurality of discrete operating positions, which are associated with different opening cross sections. The valve can also have continuously different opening cross sections, wherein the different opening cross sections may or may not have a fully closed position and / or a fully open position. For example, the valve can be designed as a proportional valve, which realizes continuously different opening cross sections according to different electrical excitations. It is also possible to provide a plurality of different opening cross sections by designing the valve as a pulse width modulation valve, wherein the duty cycle of the pulse width modulation is related to the opening cross section. In this design, the control unit has a control logic, which increases the opening cross section when the difference between the target temperature in the centrifugal kettle and the temperature detected by the temperature sensor is greater than a threshold value. However, in this case, the increase in the opening cross section depends on the magnitude of the difference, the rate of change of the difference and / or the time span during which the difference is greater than the threshold value. For example, initially the opening of the valve may only be slightly increased. If the control logic of the control unit subsequently determines that the temperature in the centrifugal kettle is still too low, the opening of the valve can be further increased. Within the scope of the present invention, the opening cross section can also be controlled or its size can be adjusted according to the operating parameters of the centrifuge, in particular the actual temperature in the centrifuge tank.

[0027] According to the invention, the control logic of the control unit operates in two different modes:

[0028] When the difference between the target temperature in the centrifugal reactor and the temperature detected by the temperature sensor is less than the threshold value (or the second threshold value), it is the normal operation mode. In the normal operation mode, the control logic completely controls or regulates only the adjustable expansion device and / or the adjustable compressor. In the normal operation mode, the valve is in the first position.

[0029] If the difference between the target temperature in the centrifuge and the temperature detected by the temperature sensor is greater than the threshold value (or a specified second threshold value), an abnormal operating mode is reached. In the abnormal operating mode, the control logic controls the valve to a second position different from the first position. According to the invention, in the abnormal operating mode, no additional control or regulation is performed with the aid of the compressor, preferably also without the aid of an adjustable expansion device. For this proposal of the invention, in the first position of the valve, the opening cross section of the valve is smaller than the opening cross section of the valve in the second position.

[0030] If a 2 / 2 solenoid valve is used as the valve, the first position can be the blocking position and the second position can be the conducting position. Conversely, if a valve of another design is used, whose opening cross section can be changed continuously or in discrete steps, any partial opening can be performed in the first position and / or the second position.

[0031] According to one proposal of the invention, in the centrifuge, the compressor is permanently operated during the operation of the laboratory centrifuge, wherein the speed during operation always corresponds to at least the minimum speed. Thus, the design according to the invention can avoid shutting down the compressor, which is beneficial on the one hand to the operation and service life of the compressor and the lubrication conditions, and on the other hand to avoid undesirable mixing of the centrifuged material due to stopping and restarting the compressor.

[0032] Another solution to the object of the present invention is a method for operating a centrifuge. Here, the construction of the centrifuge is essentially the same as explained above in various designs and developments. In one method step, it is first checked whether the difference between the target temperature in the centrifuge tank and the temperature detected by the temperature sensor is greater than a threshold value. If the check shows that the difference is greater than the threshold value, the flow through the bypass line is increased in the method of the present invention.

[0033] According to one proposal of the invention, in the method the refrigerant flow through the evaporator is (also or exclusively) controlled or regulated by a passive thermostatic injection valve.

[0034] In the method of the present invention, the refrigerant may be conveyed in the refrigerant circuit by means of a rolling piston compressor.

[0035] Furthermore, in the method of the invention, the valve can also be controlled to a plurality of different opening cross sections (continuous or discretely graded). If the difference between the target temperature in the centrifugal reactor and the temperature detected by the temperature sensor is greater than a threshold value, the opening cross section is increased. In this case, the increase and the degree of increase are related to the magnitude of the determined difference, the speed of change of the difference and / or the time span during which the difference is greater than the threshold value.

[0036] According to the present invention, a check is performed to determine whether the difference between the target temperature in the centrifuge tank and the temperature detected by the temperature sensor is less than a threshold value (or a different second threshold value).

[0037] If this is the case, the centrifuge is operated in a normal operating mode. In the normal operating mode, control or regulation is performed by means of an adjustable expansion device and / or by means of a compressor. In the normal operating mode, the valve is in a first position.

[0038] If, on the other hand, the difference is greater than the threshold value (or the second threshold value), the centrifuge is operated in an abnormal operating mode. In the abnormal operating mode, the valve is controlled to a second position different from the first position. In the abnormal operating mode, no control or regulation is performed by the compressor, preferably also not by an adjustable expansion device. In this design of the method of the invention, the opening cross section of the valve in the first position is smaller than the opening cross section of the valve in the second position.

[0039] In a further embodiment of the method according to the invention, the compressor is operated permanently during operation of the centrifuge, wherein during this operation the rotational speed always corresponds to at least a minimum rotational speed.

[0040] Another solution to the task of the present invention is a computer-readable medium having control logic for executing the above-mentioned method for operating a centrifuge. For example, the control logic on this computer-readable medium can be used to implement the method of the present invention or upgrade the control software on an existing centrifuge afterwards.

[0041] Further advantageous developments of the invention emerge from the claims, the description and the drawings.

[0042] The advantages of the features and combinations of multiple features mentioned in the specification are merely exemplary and may be achieved alternatively or cumulatively, and these advantages do not necessarily have to be achieved by the embodiments of the present invention.

[0043] With regard to the disclosure of the original application documents and the patent (but not the scope of protection), the following applies: Further features can be derived from the drawings (in particular the geometric shapes shown in the drawings, the relative dimensions of several components and their relative arrangement and effective connection). The combination of features of different embodiments of the invention or features of different claims may also deviate from the selected references to the claims and be given here. This also applies to features shown in separate drawings or mentioned in the description. These features may also be combined with features in different claims. Similarly, in further embodiments of the invention, the features listed in the claims may also be omitted, but this does not apply to independent claims of granted patents.

[0044] The features mentioned in the claims and the description are to be understood as referring to exactly this number or more than the number mentioned, without the explicit use of the adverb "at least". Thus, for example, when a valve or an expansion device is mentioned, it is to be understood that there is exactly one valve or one expansion device, two valves or two expansion devices or more valves or more expansion devices. The features listed in the claims may be supplemented by other features or may be the only features possessed by the subject matter of the respective claim.

[0045] The reference numerals included in the claims do not limit the scope of the subject matter protected by the claims. They are only intended to make the claims easier to understand. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention will be further explained and illustrated below with reference to the preferred embodiments shown in the drawings.

[0047] FIG. 1 schematically shows a laboratory centrifuge with a refrigerant circuit according to the prior art.

[0048] FIG. 2 schematically shows a laboratory centrifuge with a refrigerant circuit according to EP 2 814 617 B1.

[0049] Figure 3 A centrifuge with a refrigerant circuit is shown schematically.

[0050] Figure 4 The method for operating a centrifuge with a refrigerant circuit is schematically illustrated. DETAILED DESCRIPTION

[0051] Figure 3 A centrifuge 19 with a centrifuge tank 3 and a refrigerant circuit 1 is schematically shown, in which a compressor 4, a liquefier 5, an expansion device 6 (which can be designed as a thermostatic injection valve 7 or an electronically controlled expansion device or throttling device 11) and an evaporator 2 are connected to one another in a circuit. The connecting line 17 between the compressor 4 and the liquefier 5 is connected to the connecting line 16 between the expansion device 6 and the evaporator 2 via a bypass line 15, in which an electronically controlled valve 20 is arranged. If the expansion device 6 is designed as a thermostatic injection valve 7, it preferably has a spring 9 and a pressure-controlled temperature detector 8 with a sensor 10 (see FIG. 1 and the prior art cited at the beginning of this article).

[0052] exist Figure 4. First, the centrifuge 19 is operated in a normal operating mode 21 (possibly after the centrifuge 19 has started operation). In the normal operating mode 21, the temperature in the centrifuge tank 3 is regulated in a method step 22. In this regulation, the flow rate of the refrigerant and the opening size or throttling effect of the expansion device 6 are first regulated. As shown in the figure, if a thermostatic injection valve 7 is used as the expansion device 6, the regulation can be passive or passive. However, the temperature in the centrifuge tank 3 can also be obtained by a temperature sensor 23, and the electronic injection valve or the electronic throttling device 11 can be controlled by the control unit according to the requirements. Alternatively or additionally, the temperature can also be controlled or regulated by the control unit by controlling the adjustable compressor 4. In a method step 24, which can be performed in the above control or regulation process, the difference between the predetermined target temperature in the centrifuge tank (for example, input by the user and stored in the control unit or read from the characteristic diagram of the selected operating data) and the temperature detected by the temperature sensor 23 (i.e. the actual temperature, wherein the measured temperature can also be corrected or converted into the actual temperature of the centrifuge chamber in the centrifuge tank 3 or an estimated value of the actual temperature) is determined. In method step 25 , the difference is compared with a threshold value, which may be, for example, 5 K, 3 K or 1 K. If the difference is less than the threshold value and the actual temperature is therefore less than the target temperature by less than the threshold value, normal operating mode 21 can be continued, in which method step 22 is returned to.

[0053] On the contrary, if the difference between the target temperature and the actual temperature is greater than the threshold value and the degree to which the actual temperature is less than the target temperature is greater than the threshold value, the normal operating mode 21 is switched to the abnormal operating mode 26. In the abnormal operating mode 26, the valve 20 is controlled by the control unit in method step 27 so that the flow in the bypass line 15 is increased. The valve 20 can be designed as a 2 / 2 solenoid valve. In this case, the 2 / 2 solenoid valve 28 is controlled in method step 27 so that it is turned from the closed position to the conducting position. Optionally, further measures can be taken in method step 29 to increase the actual temperature, for example, by appropriately controlling the adjustable compressor 4 and / or controlling the expansion device 6. This state can be maintained for a predetermined time span. Immediately thereafter or after this time span, it is checked in method step 30 whether the difference between the target temperature and the actual temperature is still greater than the threshold value. If so, the abnormal operating mode 26 is continued and the valve 20 is opened in method step 27, further opened than before or the open state of the valve 20 is maintained. If, on the other hand, the actual temperature rises below the target temperature by a maximum threshold value, the system returns to normal operating mode 21 , so that method steps 22 , 24 , 25 are carried out again.

[0054] It is also possible to connect the valve 20 in parallel with a line section with a predetermined conduction cross section or a throttle valve with a predetermined throttling cross section in the bypass line 15, so that a flow is permanently ensured through the bypass line 15 via this line section. In this case, the flow ensured in this way can be additionally influenced depending on the opening position of the valve 20. In this case, the valve 20 can also be designed as a 2 / 2 solenoid valve or any other discretely or continuously adjustable valve.

[0055] The compressor 4 is preferably designed as a rolling piston compressor 31 .

[0056] List of reference numerals:

[0057] 1 Refrigerant circuit

[0058] 2 Evaporator

[0059] 3 Centrifugal kettle

[0060] 4. Compressor

[0061] 5Liquifier

[0062] 6 Expansion device

[0063] 7Thermostatic injection valve

[0064] 8Pressure control temperature detector

[0065] 9 Spring

[0066] 10 Filling

[0067] 11 Electronically controlled expansion device or electronically controlled throttling device

[0068] 12 Temperature Sensor

[0069] 13. Temperature Sensor

[0070] 14 Temperature Sensor

[0071] 15 Bypass line

[0072] 16 Connecting pipes

[0073] 17 Connecting pipes

[0074] 18 Electronically controlled injection valve

[0075] 19 Centrifuge

[0076] 20 valve

[0077] 21 Normal operation mode

[0078] 22 Methods and Steps

[0079] 23. Temperature sensor

[0080] 24 Methods and Steps

[0081] 25 Methods and Steps

[0082] 26 Abnormal operation mode

[0083] 27 Methods and Steps

[0084] 28 2 / 2 solenoid valve

[0085] 29 Methods and Steps

[0086] 30 Methods and Steps

[0087] 31 Rolling piston compressor.

Claims

1. A centrifuge (19), in particular a flow-through centrifuge, a biotechnological centrifuge or a blood centrifuge, comprising: a) a centrifugal kettle (3); b) a refrigerant circuit (1) with a circulating refrigerant; and c) a temperature sensor (23) which detects a temperature which is at least related to the temperature in the centrifuge tank (3), in, c) The refrigerant circuit (1) has: ca) an adjustable compressor (4); cb) liquefier (5); cc) a variable expansion device (6); and cd) an evaporator (2) for delivering cold to the centrifugal kettle (3); d) the connecting pipeline (17) from the compressor (4) to the liquefier (5) is connected to the connecting pipeline (16) between the expansion device (6) and the evaporator (2) via a bypass pipeline (15), and e) an electronically controlled valve (20) for controlling the flow is arranged in the bypass line (15), It is characterized in that f) there is an electronic control unit having a control logic, which controls the valve (20) so that the flow rate through the bypass line (15) increases when the difference between the target temperature in the centrifugal tank (3) and the temperature detected by the temperature sensor (23) is greater than a threshold value, and g) The control unit has a control logic, which ga) in normal operation mode (21), i.e. when the magnitude of the difference between the target temperature in the centrifugal tank (3) and the temperature detected by the temperature sensor (23) is less than the threshold value or the second threshold value, control and / or regulation is performed by the expansion device (6) and / or by the compressor (4), with the valve (20) being in the first position, and gb) in an abnormal operation mode (26), i.e., when the magnitude of the difference between the target temperature in the centrifugal tank (3) and the temperature detected by the temperature sensor (23) is greater than the threshold value or the second threshold value, controlling the valve (20) to a second position different from the first position, wherein In the abnormal operating mode (26), no control or regulation is performed by the compressor (4), Preferably, in the abnormal operating mode (26), control and regulation are not performed by the expansion device (6). gc) wherein, in the first position of the valve (20), the opening cross section of the valve (20) is smaller than the opening cross section of the valve (20) in the second position.

2. The centrifuge (19) according to claim 1, characterized in that a) the valve (20) is a 2 / 2 solenoid valve (28) having a larger opening position and a smaller opening position, in particular having an on position and a off position, and b) The control unit has a control logic, when the difference between the target temperature in the centrifugal tank (3) and the temperature detected by the temperature sensor (23) is greater than a threshold value, the control logic controls the 2 / 2 solenoid valve (28) from the smaller open position to the larger open position, wherein the control logic preferably controls the 2 / 2 solenoid valve (28) from the smaller open position to the larger open position for a predetermined time span.

3. The centrifuge (19) according to any one of the preceding claims, characterized in that The expansion device (6) is a passive thermostatic injection valve (7).

4. The centrifuge (19) according to any one of the preceding claims, characterized in that The compressor (4) is a rolling piston compressor (31).

5. The centrifuge (19) according to any one of claims 1, 3 and 4, characterized in that The valve has a plurality of different opening cross sections and the control unit has a control logic. When the difference between the target temperature in the centrifugal tank (3) and the temperature detected by the temperature sensor (23) is greater than a threshold value, the control logic increases the opening cross section according to the magnitude of the difference, the speed of change of the difference and / or the time span during which the difference is greater than the threshold value.

6. The centrifuge (19) according to any one of the preceding claims, characterized in that During operation of the centrifuge (19), the compressor (4) is operated permanently, wherein during operation the rotational speed always corresponds to at least a minimum rotational speed.

7. A method for operating a centrifuge (19), in particular a flow-through centrifuge, a biotechnological centrifuge or a blood centrifuge, comprising: A centrifugal tank (3), a refrigerant circuit (1) with a circulating refrigerant, and a temperature sensor (23) for detecting a temperature at least related to the temperature in the centrifugal tank (3), wherein the refrigerant circuit (1) comprises an adjustable compressor (4), a liquefier (5), an expansion device (6), and an evaporator (2) for supplying cold to the centrifugal tank (3), wherein a connecting line (17) from the compressor (4) to the liquefier (5) is connected to a connecting line (16) between the expansion device (6) and the evaporator (2) via a bypass line (15), and an electronically controlled valve (20) for controlling the flow is arranged in the bypass line (15), wherein the method comprises the following method steps: a) checking whether the difference between the target temperature in the centrifugal tank (3) and the temperature detected by the temperature sensor (23) is greater than a threshold value, b) if the check shows that the difference is greater than the threshold value, the flow through the bypass line (15) is increased, c) Among them, Checking whether the value of the difference between the target temperature in the centrifugal tank (3) and the temperature detected by the temperature sensor (23) is less than the threshold value or the second threshold value, and ca) If this is the case, the centrifuge (19) is in normal operating mode (21) In a normal operating mode, control and / or regulation is performed by the expansion device (6) and / or by the compressor (4), the valve (20) being in a first position, and cb) If this is not the case, the centrifuge (19) is in an abnormal operating mode (26) in an abnormal operating mode, in which the valve (20) is controlled to a second position different from the first position, wherein in the abnormal operating mode (26), control and / or regulation is not performed by the compressor (4), wherein preferably, in the abnormal operating mode (26), control and / or regulation is not performed by the expansion device (6), either, Wherein, in the first position of the valve (20), the opening cross section of the valve (20) is smaller than the opening cross section of the valve (20) in the second position.

8. The method according to claim 7, characterized in that The refrigerant flow through the evaporator (2) is controlled or regulated by a passive thermostatic injection valve (7).

9. The method according to claim 7 or 8, characterized in that: Refrigerant is transported in the refrigerant circuit (1) via a rolling piston compressor (31).

10. The method according to any one of claims 7 to 9, characterized in that a) the valve (20) is controlled to a plurality of different opening cross sections, and b) checking whether the difference between the target temperature in the centrifugal tank (3) and the temperature detected by the temperature sensor (23) is greater than a threshold value, and if so, increasing the opening cross section of the valve (20) according to the magnitude of the difference, the speed of change of the difference and / or the time span during which the difference is greater than the threshold value.

11. The method according to any one of claims 7 to 10, characterized in that During operation of the centrifuge (19), the compressor (4) is operated permanently, wherein during operation the rotational speed always corresponds to at least a minimum rotational speed.

12. A computer-readable medium having a control logic for executing the method according to one of claims 7 to 11 for operating a centrifuge (19), in particular a flow-through centrifuge, a biotechnological centrifuge or a blood centrifuge.

Images