Centrifuge, method for operating a centrifuge, and computer-readable medium

Abstract

The present invention relates to a centrifuge 19, in particular a continuous centrifuge, a centrifuge for biotechnology or a centrifuge for blood. The centrifuge 19 has a refrigerant circuit 1. According to the present invention, the output side of the controllable compressor 4 is coupled to the input side of the evaporator 2 via this bypass pipe 15 having a valve 20 arranged in the bypass pipe 15. In the normal operation mode, when the valve 20 is closed, the centrifuge bowl 3 is cooled only by the control of the compressor 4 and the expansion device 6. On the other hand, when the temperature in the centrifuge bowl 3 falls below the allowable range of the set temperature in the centrifuge bowl 3, the valve 20 is opened in order to return the temperature in the centrifuge bowl 3 within the allowable range.

Description

Technical Field

[0001] The present invention relates to a centrifuge.

Background Art

[0002] The centrifuge is preferably a continuous centrifuge. In the case of this continuous centrifuge, at least one medium is supplied to and / or discharged from the centrifugation chamber at least temporarily while the centrifugation chamber is rotating. The at least one medium is in particular the medium to be centrifuged, a cleaning liquid, a buffer, a corrective medium extracted from the centrifuged medium or a precipitate in the centrifugation chamber. Just to list a few non-limiting examples of the present invention, the continuous centrifuge can be a centrifuge for blood where the medium to be centrifuged is blood and the corrective medium or precipitate extracted is blood cells or blood particles, or a centrifuge where particles contained in cells, microcarriers or other media are obtained from the medium. The centrifuged medium can also be a solution or suspension containing particles such as cells, cell debris or cell fragments and not a pure liquid. Such a continuous centrifuge is used, for example, in biopharmaceutical companies or bioprocessing equipment for manufacturing biopharmaceutical or biotechnology products. In this case, the continuous centrifuge is used, for example, to recover and / or purify cells or microcarriers. In this case, the cells thus obtained can be used for cell therapy. Other application fields are the production of vaccines or the treatment of blood to obtain blood cells (among others). Such continuous centrifuges are sold, for example, by Sartorius AG (Otto-Brenner-Strasse 20, 37079 Goettingen, Germany) and related companies under the designation "Ksep®". See also www.sartorius.com / en / products / process-filtration / cell-harvesting / ksep-systems (date of viewing: June 28, 2022).

[0003] Such a rotor of a continuous centrifuge can be formed, in particular, as a bag held in the rotor body and has four centrifugation chambers evenly arranged over the circumference. In this case, these centrifugation chambers are arranged radially spaced apart from the axis of rotation of the rotor. A first connecting pipe leads radially from the inside to the centrifugation chamber, while a second connecting pipe leads radially from the outside to this centrifugation chamber. In a first operating phase, for example, a first medium configured as blood is supplied to the centrifugation chamber via the second connecting pipe, while the centrifugation chamber rotates together with the rotor. Inside the centrifugation chamber, as a result of centrifugation, the particles contained in the medium precipitate radially outwards, while the residual medium (the medium supplied radially from the outside is only reduced by the particles pushed radially outwards) is discharged from the centrifugation chamber via the first connecting pipe. Thus, in this first operating phase, the first connecting pipe is the discharge pipe, while the second connecting pipe is the supply pipe. With the continuation of this operation until the centrifugation chamber is almost or completely filled with particles, the proportion and concentration of the particles in this centrifugation chamber increase. In a subsequent optional second operating phase, the particles in the centrifugation chamber are washed. For this purpose, a washing liquid or buffer solution is sent to the centrifugation chamber via the second connecting pipe. The washing liquid or buffer solution passes through the centrifugation chamber and is discharged radially from the inside via the first connecting pipe. Also in this operating phase, as a result of the acting centrifugal force, the centrifugation chamber rotates together with the rotor so that the particles are prevented from flowing out of the centrifugation chamber via the first connecting pipe together with the washing liquid or buffer solution. Also during this second operating phase, the first connecting pipe is used as the discharge pipe for the washing liquid or buffer solution, while the first connecting pipe is used as the supply pipe for the washing liquid or buffer solution. In a subsequent third operating phase, the centrifugation chamber continues to rotate together with the rotor. In this third operating phase, the direction of flow into the centrifugation chamber is reversed, and the particles are removed from the centrifugation chamber via the second connecting pipe, while the washing liquid or buffer solution is supplied to the centrifugation chamber via the first connecting pipe. The third operating phase ends when all the particles have been removed from the centrifugation chamber.Subsequently, further cycles are continuously executed by the three described operating phases.

[0004] Such continuous centrifuges that can be used in the present invention are known, for example, from European Patent No. 3936601, European Patent No. 2310486, European Patent No. 2485846, US Patent No. 4,216,770, US Patent No. 4,419,089, US Patent No. 4,389,206, and US Patent No. 5,665,048.

[0005] The centrifuge according to the present invention can have a horizontal axis of rotation. In this case, the medium (for example, blood, cleaning liquid, and particles) can be exchanged within the region of the rotor shaft that rotates during centrifugation. The continuous centrifuge thus configured can be, for example, a centrifuge for blood in which blood is centrifuged as the medium.

[0006] Furthermore, the present invention relates to a method and a computer-readable medium for operating such a centrifuge.

[0007] European Patent No. 2814617 discloses the following information regarding the prior art for cooling a laboratory centrifuge.

[0008] During centrifugation, especially in a laboratory centrifuge that rotates at a very high speed, heat due to air friction and power loss is generated inside the centrifuge bowl during the rotation of the rotor of the centrifuge. Since the centrifuge bowl is sealed by a lid to prevent the outflow of the centrifuged material, such heat dissipation cannot be easily carried out, and the temperature of the centrifuged material rises. However, since such a temperature rise can destroy or render unusable the centrifuged sample, such a temperature rise is undesirable. Generally, the sample must be maintained at a predetermined temperature, for example, 4°C, 22°C, or 37°C depending on the application. Therefore, conventionally, measures have already been taken to avoid the temperature rise of the centrifuged material. In this case, indirect cooling is frequently used. In the case of this indirect cooling, the rotor is sealed under the lid of the centrifuge inside the centrifuge bowl, and no cooling channels or the like are provided. Therefore, air circulates only inside the centrifuge bowl. At this time, cooling is achieved by a second medium that is induced along the outer surface of the bowl or induced into the bowl. For this reason, in many cases, a refrigerant circuit having a compressor, piping, and a heat exchanger is provided. To carry out the heat, a special refrigerant is induced along the bowl by the refrigerant circuit, for example, via piping that spirally contacts the centrifuge bowl, that is, the side wall and the floor of the bowl. Different from, for example, the "refrigerant" used for the cooling water circuit of an automobile, the refrigerant undergoes a phase change during the flow through the refrigerant circuit, that is, it changes from a liquid to a gas. Temperature adjustment of the cooling object having a temperature lower than the ambient temperature is also possible by such a refrigerant. Cooling the sample article to a temperature lower than the ambient air temperature is also possible by the refrigerant circuit. Such a laboratory centrifuge is known, for example, from German Patent Application Publication No. 3818584 and Japanese Unexamined Patent Application Publication No. 2011-255330. Such a refrigerant circuit 1 has an evaporator 2, a compressor 4, a condenser 5, and an expansion device 6 that are annularly provided around the centrifuge bowl 3 (see FIG. 1). In this case, the expansion device 6 is designed to correspond to the maximum load state, that is, the maximum rotational speed of the rotor of the centrifuge (not shown). In this case, the expansion device 6 (the pressure adjustment element between the high-pressure side and the low-pressure side of the refrigerant circuit 1 when the compressor 4 stops) is configured as a capillary tube or a thermostatic expansion valve 7 (abbreviated as "TEV").In cooperation with the pressure-controlled temperature detection unit 8 behind the evaporator 2, this thermostat-type injection valve 7 is used to increase or decrease the refrigerant flow rate in the refrigerant circuit 1 depending on the temperature detected at the input part VE of the evaporator. For the increase or decrease of the refrigerant flow rate, superheat of the refrigerant at the output part VA of the evaporator is required so that an overpressure directly applied to the spring 9 of the thermostat-type injection valve 7 is generated to control this thermostat-type injection valve 7. More precisely, the output part VA of the evaporator reaches a specific temperature. The sensor 10 of the thermostat-type injection valve 7 is fixed to the output part VA of the evaporator. Similarly, a refrigerant that can correspond to the refrigerant in the refrigerant circuit 1 is included in the thermostat-type injection valve 7. Due to the said temperature of the output part VA of the evaporator, the said refrigerant acts on the thermostat-type injection valve 7 and the repulsive force of the spring 9 at this time, and thus has an appropriate pressure to open and close the thermostat-type injection valve 7. Here, by another control unit which is a frequency-controlled or rotation speed-controlled compressor 4, a part of other load states can be controlled, although often inaccurately. Since superheat of the refrigerant is required to make the thermostat-type injection valve 7 function, the performance of the evaporator cannot be fully utilized. In this case, only about 95% of the surface area of the evaporator can be utilized. For the said superheat, the temperature difference between the input part VE and the output part VA of the evaporator needs to be about 7K. Another major drawback of such a known refrigerant circuit 1 in a centrifugal separator is that the compressor 4 can be controlled only relatively inaccurately and only within a specific output range. As a result, depending on different partial load states or small load states, it is necessary to completely stop the compressor 4. However, this is not always possible. Because in order to ensure the internal oil circulation, the compressor 4 generally has a minimum operating time. On the contrary, when the drive motor of the compressor 4 is heated more strongly during startup and necessary pressure adjustment, or when the pressure difference between the high-pressure side and the low-pressure side decreases, such a compressor 4 stops for a specific minimum period. Therefore, the control performance by the compressor 4 is strongly limited especially within a low output range. Another drawback is that vibrations occur when the compressor 4 of the refrigerant circuit 1 starts or stops.When this vibration affects the operating behavior of the centrifuge, increases the reverse mixing rate in the rotor after the centrifuge stops, and affects adjacent experimental equipment and the like. Ultimately, the lifespan of the compressor 4 is shortened due to its frequent on-off operation.

[0009] Based on this, European Patent No. 2814617 proposes a refrigerant circuit 1 in which the expansion device 6 is configured as an electronically continuously or discontinuously controllable throttle (and can also be configured as an electronic injection valve 11) (see FIG. 2). Temperature sensors 12, 13, 14 detect the temperature of the refrigerant at the input part VE of the centrifuge bowl 3, the actual temperature inside the centrifuge bowl 3, and the temperature at the output part VA of the centrifuge bowl 3. The temperature signals of the temperature sensors 12, 13, 14, the set temperature of the centrifuge bowl 3, and the allowable range (especially ±5K) of the actual temperature of the centrifuge bowl 3 with respect to the set temperature are supplied to the electronic control device. The electronic control device operates the electronic injection valve 11 and the controllable compressor 4 for temperature control. A bypass pipe 15 connects the connecting pipe 16 between the electronic injection valve 11 and the evaporator 2 to the connecting pipe 17 between the output part of the compressor 4 and the evaporator 2. An electronic injection valve 18 is arranged in the bypass pipe 15. It is also possible for the electronic control device to control the electronic injection valve 18. According to European Patent No. 2814617, if necessary, coarse adjustment and fine adjustment are switched as follows: Coarse adjustment is carried out at the start of the laboratory centrifuge until the actual temperature is within the allowable range during a preset period. Thereafter, a switch is executed, and fine adjustment is basically maintained during further operation. Despite the fine adjustment, coarse adjustment is executed again only when the actual temperature deviates from the allowable range. During coarse adjustment, only the compressor 4 is controlled without controlling the electronic injection valves 11, 18. In contrast, during fine adjustment, the output of the compressor 4 is not changed. At this time, the control is executed by controlling the electronic injection valve 11. In this case, during the fine adjustment, the electronic injection valve 11 is controlled based on three different criteria. First, when the actual temperature of the centrifuge bowl 3 tends to decrease (or increase) within a preset trend period, the electronic injection valve 11 is controlled downward (or upward). Thereby, the refrigerant flow rate is decreased (or increased). Also, when the temperature of the refrigerant at the input part VE of the evaporator 2 is lower than a preset threshold value of the temperature at the input part VE of the evaporator 2, the opening amount of the electronic injection valve 11 is controlled. In this case, this opening amount is maintained until the temperature becomes larger than the preset threshold value of the temperature again.In this way, the operation of the compressor 4 within the vacuum region is avoided. Finally, the difference between the temperature at the output section VA of the compressor and the temperature at the input section VE of the compressor is also monitored. In order to maintain the maximum operating rate of the evaporator 2 and avoid the liquid refrigerant from reaching the compressor 4, this difference must be between 0K and 1K. When the difference falls below the specified value, the electronic injection valve 11 is further closed and / or the frequency of the compressor is decreased.

[0010] Japanese Patent Application Laid-Open No. 2010-008022 discloses a refrigerant circuit for a centrifuge. In the case of this centrifuge, during normal operation mode without control options, the refrigerant flows from the compression amount through two capillary tubes arranged in series with a condenser and a dryer to the evaporator. If the temperature of the centrifugal bowl cooled as a result is too low, the bypass valve is shifted to the open position. As a result, the refrigerant can flow from the output section of the compressor through the bypass pipe and through the capillary tube arranged downstream of the output section of the compressor to the evaporator. In this case, the refrigerant flowing through the bypass pipe bypasses the condenser and the capillary tube arranged upstream. In order to set the flow rate of the refrigerant in the parallel pipe branch when the solenoid valve is open, the inner shape of the capillary tube arranged upstream is selected to be smaller than the inner shape of the capillary tube arranged downstream.

[0011] European Patent Application Publication No. 0295377 discloses a refrigerant circuit for a centrifuge. In the case of this centrifuge, the output section of the compressor is connected to the cooling coil of the centrifuge bowl through a parallel circuit of a high-temperature pipe and a low-temperature pipe (where the condenser is arranged). Pulse width modulation valves are arranged in each of the high-temperature pipe and the low-temperature pipe. In this case, these valves are operated alternately. In this case, the heat supplied to the cooling coil depends on the pulse width controlled based on the measured temperature within the centrifuge bowl.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

[0013] The problem of the present invention is to improve the response performance to an undesired decrease in temperature in a centrifuge bowl in the configuration of a centrifuge and a method for operating the centrifuge. Further, the present invention aims to provide a computer-readable medium having a control logic unit for an appropriately improved method. [Means for Solving the Problems]

[0014] According to the present invention, the problem of the present invention is solved by the features described in the independent claims. Other preferred configurations of the present invention are described in the dependent claims.

[0015] The present invention relates to a centrifuge having a centrifuge bowl. Further, the centrifuge particularly has a refrigerant circuit in which a refrigerant that undergoes a phase change within the centrifuge bowl circulates. The refrigerant circuit is used to cool the centrifuge bowl in order to guarantee a set temperature within an allowable range inside the centrifuge bowl.

[0016] In the centrifuge, the temperature inside the centrifuge bowl is detected (directly or indirectly) by a temperature sensor. To give some examples that do not limit the invention, the temperature sensor can be arranged on the wall of the centrifuge bowl or on the lid of the centrifuge, and in particular can be arranged as closely as possible to the centrifugation chamber of the centrifuge bowl or can be directly adjacent to this centrifugation chamber. However, it is also possible for the temperature sensor to be incorporated in the rotor or in a centrifuge container for the centrifugate held by the rotor (see also European Patent Application Publication No. 3560592).

[0017] The refrigerant circuit used within the scope of the present invention has a compressor whose rotational speed, frequency and / or output is controllable. Further, the refrigerant circuit has a condenser, particularly a capacitor. Further, an adjustable expansion device is arranged in the refrigerant circuit. The refrigerant circuit also has an evaporator for cooling the centrifuge bowl. Thus, for example, the evaporator can surround the centrifuge bowl by piping or the piping can be incorporated into the side wall of the centrifuge bowl. In the refrigerant circuit, the adjustable expansion device is particularly arranged upstream of the evaporator. The control of the refrigerant flow rate and / or the expansion of the refrigerant, that is, the state of the pressure behavior and temperature behavior of the refrigerant in the low-pressure side and in the region of the evaporator, can be affected by the adjustable expansion device. In this case, the adjustable expansion device can be configured passively, and in particular can be a thermostatic injection valve, or can be configured actively, and in particular can be configured as an electronically controlled throttle or other electronically controlled expansion device.

[0018] According to the present invention, a connecting pipe connecting a compressor to a condenser is connected to a connecting pipe between an expansion device and an evaporator via a bypass pipe. Preferably, the bypass pipe bypasses the condenser and an adjustable expansion device. In this case, the bypass pipe connects between the high-pressure side and the low-pressure side of the refrigerant circuit. To control the connection, an electronically controlled valve for controlling the flow rate flowing through the bypass pipe is arranged in the bypass pipe.

[0019] The present invention proposes that a centrifugal separator is provided with an electronic control device having a control logic unit. The control logic unit monitors the difference between a preset temperature in the centrifugal separator bowl and the temperature detected by a temperature sensor, that is, the actual temperature in the centrifugal separator bowl. When this difference is greater than a preset threshold value, the valve arranged in the bypass pipe is operated by the control device so that the flow rate flowing through this bypass pipe is increased. Preferably, when the compressor has already been set to the minimum output by the control device and / or when the expansion device is operated by the control device so that heat is maximally absorbed by the evaporator, the increase in the flow rate is executed. Therefore, the conventional means for avoiding a decrease in the temperature in the centrifugal separator bowl have already been exhausted, and nevertheless, when the set temperature is below the threshold value, preferably, the valve is controlled to increase the flow rate flowing through the bypass pipe (without the means of the present invention, it may be necessary to stop the compressor in some cases). In this case, by the control of the valve, more refrigerant flows from the high-pressure side to the low-pressure side and reaches the input part of the evaporator. Therefore, the amount of the higher-temperature refrigerant on the high-pressure side mixed into the low-pressure side of the input part of the evaporator increases. As a result, finally, the amount of heat released from the evaporator to the centrifugal separator bowl can be reduced. Thus, an excessive decrease in the temperature in the centrifugal separator bowl can be avoided. This can be achieved without the need to stop the compressor or without the need to significantly reduce the output of the compressor.

[0020] Basically, there are various options regarding the type of valve (e.g., poppet valve, slide valve, …) arranged in the bypass pipe, the operating position (continuous operating position, any number of discrete operating positions), and the possible operations, as long as it can be controlled by the electronic control device. Any valve suitable for this purpose known from the prior art can be used. In the present invention, it is proposed that the valve is configured as a two-way solenoid valve having a larger open position and a smaller open position. For example, it is possible that the smaller open position is the shut-off position and the larger open position is the flow-through position. In this case, basically, the valve is in the shut-off position where the bypass pipe is closed. The two-way solenoid valve is controlled from the control position to the flow-through position only when the difference between the set temperature in the centrifuge bowl and the temperature detected by the temperature sensor is greater than the threshold value. In this case, the two-way solenoid valve takes its shut-off position without electrical excitation by the control device, while electrical excitation is possible to switch to the flow-through position. However, it is also possible to design the valve conversely so that the valve is shifted to the shut-off position by electrical excitation. In this case, a stable position of the valve that can be released only by electrical excitation can be held by a spring. In another embodiment, the valve can be configured as a bistable valve that holds the flow-through position and the shut-off position once set without the need for excitation of this valve. Electrical excitation of the valve is required only to switch the valve position in both directions.

[0021] There are various options for the criteria to control the two-way solenoid valve to the flow-through position. For example, the two-way solenoid valve can be controlled to the flow-through position until the difference between the set temperature in the centrifuge bowl and the temperature detected by the temperature sensor becomes smaller again than a threshold value or any other temperature correlated with the set temperature. In a very simple configuration of the present invention, the control logic unit controls the two-way solenoid valve from the shut-off position to the flow-through position for a predetermined period. In this case, to give some examples without limiting the present invention, the predetermined period may depend on the operating parameters of the centrifuge that may be related to the rotational speed of the centrifuge, the ambient temperature of the centrifuge, the actual centrifuged material and / or the type of rotor used in the centrifuge. During the operation of the centrifuge, it is also possible that the period during which the valve is controlled to the flow-through position by the control logic unit is learned, in some cases during a number of operating cycles.

[0022] Within the scope of the present invention, any expansion device that may be an electronically controlled expansion valve or an electronically controlled throttle may be used. In a very simple configuration of the present invention, a passive thermostatic injection valve is used within the scope of the present invention as the injection device.

[0023] In the centrifuge of the present invention, any type of compressor can be used. Preferably, a rotary piston compressor is used. It has been demonstrated that the operation of this rotary piston compressor is very beneficial for unwanted vibrations on the one hand and may also be beneficial for the operation of environmentally friendly refrigerants on the other hand.

[0024] In the solution of the present invention, instead of configuring the valve as a two-way solenoid valve, a valve having a plurality of different opening cross-sections can be used. In this case, the valve has a plurality of discrete operating positions correlated with different opening cross-sections. Similarly, it is possible for the valve to have different opening cross-sections continuously. In this case, 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 configured as a proportional control valve that enables different opening cross-sections continuously in response to electrical excitation. The valve can also provide a plurality of different opening cross-sections where the valve is configured as a pulse width modulation valve. In the case of the pulse width modulation valve, the duty ratio for the pulse width modulation correlates with the opening cross-section. In such a configuration, the control device has a control logic unit. When the difference between the set temperature in the centrifuge and the temperature detected by the temperature sensor is greater than a threshold value, the control logic unit increases the opening cross-section. However, in this case, the expansion of the opening cross-section depends on the absolute value of the difference, the rate of change of the difference, and / or the period during which the difference is greater than the threshold value. For example, first, it is possible for the opening of the valve to be expanded only slightly. When the control logic unit of the control device confirms that the temperature in the centrifuge bowl is still very low, the opening is further expanded. Within the scope of the present invention, open-loop control of the opening cross-section or closed-loop control of the size of the opening cross-section may be performed based on the operating parameters of the centrifuge, particularly the actual temperature in the centrifuge bowl.

[0025] According to the present invention, the control logic unit of the control device operates in two modes: The normal operation mode can be used when the difference between the set temperature in the centrifuge bowl and the temperature detected by the temperature sensor is less than a threshold value (or a second threshold value). In the normal operation mode, the control logic unit performs open-loop control or closed-loop control only by an adjustable expansion device and / or a controllable compressor. In the normal operation mode, the valve is in the first position.

[0026] The abnormal operation mode can be used when the difference between the set temperature in the centrifuge bowl and the temperature detected by the temperature sensor is greater than the threshold value (or the second threshold value described above). In the abnormal operation mode, the control logic unit controls the valve to a second position different from the first position. In this case, according to the present invention, in the abnormal operation mode, additional open-loop control or closed-loop control by the compressor is not executed. In this case, preferably, closed-loop control or closed-loop control by the adjustable expansion device is also not executed. In the proposed invention, the opening cross-sectional area of this valve in the first position is smaller than the opening cross-sectional area of the valve in the second position.

[0027] When a two-way solenoid valve is used as the valve, the first position can be the shut-off position, while the second position can be the flow-through position. When other configurations of the valve having a continuously variable opening cross-sectional area or an opening cross-sectional area variable in discrete steps are used, any partial opening is executed at the first position and / or the second position.

[0028] In the proposed invention, the compressor is constantly operated inside the centrifuge during the operation of the laboratory centrifuge. In this case, during the operation, the rotational speed always matches at least one minimum rotational speed. Therefore, the need to stop the operation of the compressor can be avoided by this configuration of the present invention. This is beneficial on the one hand for the operation, life and lubrication state of the compressor, and on the other hand for avoiding unwanted mixing of the centrifugate due to the stop and restart of the compressor.

[0029] A further solution of the present invention is to provide a method for operating a centrifuge. In this case, basically, the centrifuge is configured as described in the above different configurations and other configurations. In one method step, first, it is checked whether the difference between the set temperature in the centrifuge and the temperature detected by the temperature sensor is greater than the threshold value. When it is confirmed that the difference is greater than the threshold value, the flow rate flowing through the bypass pipe is increased in the method of the present invention.

[0030] In the proposed invention, in this method, open-loop control or closed-loop control of the refrigerant flow rate flowing through the compressor and the passive thermostat-type injection valve (or either the compressor or the thermostat-type injection valve) is executed.

[0031] In the case of the method of the present invention, the refrigerant can be conveyed by a rotary piston compressor in the refrigerant circuit.

[0032] Furthermore, in the case of the method of the present invention, the valve can be controlled (continuously or for each discrete step) to a plurality of different opening cross-sections. At this time, when the difference between the set temperature in the centrifuge and the temperature detected by the temperature sensor is greater than the threshold value, the opening cross-section is enlarged. In this case, the enlargement and the degree of the enlargement depend on the absolute value of the calculated difference, the rate of change of the difference, and / or the period during which the difference is greater than the threshold value.

[0033] According to the present invention, it is checked whether the difference between the set temperature in the centrifuge and the temperature detected by the temperature sensor is less than the threshold value (or another second threshold value).

[0034] When the difference is less than the threshold value (or another second threshold value), the centrifuge operates in the normal operation mode. In the normal operation mode, open-loop control or closed-loop control by an adjustable expansion device and / or a compressor is executed.

[0035] On the contrary, when the difference is greater than the threshold value (or the second threshold value), the centrifuge operates in the abnormal operation mode. In the abnormal operation mode, the valve is controlled to a second position different from the first position. Therefore, in the abnormal operation mode, open-loop control or closed-loop control by the compressor is not executed. In this case, preferably, open-loop control or closed-loop control by an adjustable expansion device is not executed. In the configuration of the method of the present invention, at the first position of the valve, the opening cross-section of the valve is smaller than the opening cross-section of the valve at the second position.

[0036] In another configuration of the method of the present invention, the compressor is constantly operated during the operation of the centrifuge. In this case, the rotational speed during the operation coincides with at least one minimum rotational speed.

[0037] A further object of the present invention is to provide a computer-readable medium having a control logic unit for implementing a method for operating a centrifuge as described above. By means of the control logic unit of such a computer-readable medium, it is possible, for example, to implement the method of the present invention with an existing centrifuge or to upgrade the control software retrospectively.

[0038] The advantages of the features described in the specification and the combinations of a plurality of features are merely illustrative, and these advantages are not achieved only in the embodiments of the present invention, but can also be achieved by performing substitutions or combinations.

[0039] Regarding the disclosure content (which is not the scope of protection) of the original patent application documents, the following matters apply: Further features can be read from the drawings - in particular, the illustrated structures, the relative dimensions between a plurality of components, and the relative arrangement and action of these components. Also, combinations of features of a plurality of different embodiments of the present invention or combinations of a plurality of different claims in the claims can be made, even if they are different from the citation relationships of the selected claims in the claims, and are applicable here. This also holds true for the plurality of features shown in the individual figures or the plurality of features mentioned in the descriptions of these figures. These features may be combined with the features of different claims in the claims. Also, the features described in the claims may be omitted for other embodiments of the present invention. However, such omission does not hold true for the independent claims of the granted patent.

[0040] The features described in the claims and the specification can be construed to include that number or a number greater than that number when the adverb "at least" is not explicitly used. Thus, for example, if there is a description regarding a valve or an expansion device, this can be construed to include exactly one valve or expansion device, two valves or expansion devices, or more valves or expansion devices. The features described in the claims can be supplemented by other features or can be the unique features of the subject matter of each claim.

[0041] The reference signs described in the claims do not limit the scope of the subject matter protected by the claims. The reference signs are used only for the purpose of more easily understanding the claims.

[0042] The present invention will be further described below based on the preferred embodiments shown in the drawings.

Brief Description of the Drawings

[0043]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0044] FIG. 3 schematically shows a centrifuge 19 having a centrifuge bowl 3 and a refrigerant circuit 1. In the refrigerant circuit 1, a compressor 4, a condenser 5, a thermostatic injection valve 7 or an expansion device 6 which can be configured as an electronically controlled expansion device or a throttle 11, and an evaporator 2 are connected to each other annularly in this order. A connecting pipe 17 between the compressor 4 and the condenser 5 is connected to a connecting pipe 16 between the expansion device 6 and the evaporator 2 via a bypass pipe 15 having an electronically controlled valve 20 disposed in the bypass pipe 15. When the expansion device 6 is configured as a thermostatic injection valve 7, this thermostatic injection valve 7 preferably includes a pressure control type temperature detection unit 8 having a spring 9 and a spring 10 (see FIG. 1 and the conventional technology described at the beginning).

[0045] The method of the present invention is shown in FIG. 4. First, the centrifuge 19 is operated in the normal operation mode 21 (optionally after starting the operation of the centrifuge 19). In the normal operation mode, the control of the temperature in the centrifuge bowl 3 is executed in method step 22. In this control, first, the control of the refrigerant flow and the control of the opening amount of the expansion device 6 or the control of the throttling effect amount are executed. This is executed when the thermostat type injection valve 7 is used as the expansion device 6 as described for the passive method. However, the temperature in the centrifuge bowl 3 is measured by the temperature sensor 23, and if necessary, the electronic injection valve or the electronic throttle 11 can also be driven by the control device. Alternatively or additionally, the open-loop control or closed-loop control of the temperature can be executed by driving the compressor 4 controllable using the control device. In method step 24, which can be executed during the above open-loop control or closed-loop control, the preset set temperature in the centrifuge bowl (for example, input by the user, stored in the control device, or read from the characteristic map for the selected operating data) and the temperature detected by the temperature sensor 23 (i.e., the actual temperature (in this case, the measured temperature may be corrected or converted to the actual temperature inside the centrifuge chamber of the centrifuge 3 or an estimated value of this actual temperature)) are calculated. Then, in method step 25, this difference is compared with a threshold value that can be, for example, 5K, 3K, or 1K. If this difference is smaller than the threshold value, that is, if the actual temperature is lower than the set temperature by less than the threshold value, the normal operation mode 21 in which method step 21 is repeated can be continued.

[0046] On the other hand, when the difference between the set temperature and the actual temperature is greater than the threshold value, that is, when the actual temperature is lower than the set temperature by more than the threshold value, the normal operation mode 21 is switched to the abnormal operation mode 26. In the abnormal operation mode 26, in method step 27, the valve 20 is controlled by the control device so that the flow rate in the bypass pipe 15 is increased. The valve 20 can be configured as a two-way solenoid valve. In this case, in method step 27, the drive of the two-way solenoid valve 28 is executed so that the two-way solenoid valve 28 shifts from the closed position to the open position. Optionally, in method step 29, another measure can be taken to increase the actual temperature. This can be achieved, for example, by appropriately driving the controllable compressor 4 and / or the expansion device 6. This state can be maintained for a predetermined period. Immediately after or after this period, in method step 30, it is checked whether the difference between the set temperature and the actual temperature is still greater than the threshold value. If it is still greater than the threshold value, the abnormal operation mode 26 is maintained, and in method step 27, the valve 20 is opened, opened further than before, or the open state of the valve 20 is maintained. On the other hand, if the actual temperature has risen to a level where it is at most lower than the set temperature by the threshold value, the normal operation mode 21 is resumed. Thereby, method steps 22, 24, and 25 are executed again.

[0047] In the bypass pipe 15, it is also possible that the valve 20 is connected in parallel with the pipe section or includes a slot having a predetermined throttle cross-section. Thereby, a constant flow rate flowing through the bypass pipe 15 is guaranteed by this pipe section. In this case, the flow rate thus guaranteed can be further controlled according to the open position of the valve 20. Even in this case, the valve 20 can be configured as a two-way solenoid valve or as any other discretely or continuously adjustable valve.

[0048] Preferably, the compressor 4 can be configured as a rotary piston compressor 31.

Explanation of reference numerals

[0049] 1 Refrigerant circuit 2 Evaporator 3 Centrifuge bowl 4 Compressor 5 Condenser 6 Expansion device 7 Thermostat type injection valve 8 Pressure control type temperature detection unit 9 Spring 10 Sensor 11 Electronically controlled expansion device or electronically controlled throttle 12 Temperature sensor 13 Temperature sensor 14 Temperature sensor 15 Bypass pipe 16 Connecting pipe 17 Connecting pipe 18 Electronically controlled injection valve 19 Centrifuge 20 Valve 21 Normal operation mode 22 Method step 23 Temperature sensor 24 Method step 25 Method step 26 Abnormal operation mode 27 Method step 28 Two-way solenoid valve 29 Method step 30 Method step 31 Rotary piston compressor

Claims

1. a) a centrifuge bowl (3); b) a refrigerant circuit (1) having a circulating refrigerant; c) a temperature sensor (23) for detecting a temperature that is at least correlated with the temperature inside the centrifuge bowl (3); A centrifuge (19), in particular a continuous centrifuge, a centrifuge for biotechnology or a centrifuge for blood, comprising: c) The refrigerant circuit (1) comprises: ca) a controllable compressor (4); cb) a condenser (5); cc) a variable expansion device (6); cd) an evaporator (2) for cooling the centrifuge bowl (3); having: d) A connecting pipe (17) connecting the compressor (4) to the condenser (5) is connected to a connecting pipe (16) between the expansion device (6) and the evaporator (2) via a bypass pipe (15). e) In the centrifuge (19), an electronically controlled valve (20) for controlling the flow rate is arranged in the bypass pipe (15). f) There is an electronic control device having a control logic unit, - When the difference between the set temperature inside the centrifuge bowl (3) and the temperature detected by the temperature sensor (23) is greater than a threshold value, the control logic unit controls the valve (20) so that the flow rate flowing through the bypass pipe (15) increases. g) The control device has a control logic unit. ga) In the normal operation mode (21) where the absolute value of the difference between the set temperature inside the centrifuge bowl (3) and the temperature detected by the temperature sensor (23) is smaller than the threshold value or a second threshold value, the control logic unit executes open-loop control and / or closed-loop control by the expansion device (6) and / or the compressor (4) while the valve (20) is in the first position. gb) In the abnormal operation mode (26) where the absolute value of the difference between the set temperature inside the centrifuge bowl (3) and the temperature detected by the temperature sensor (23) is greater than the threshold value or the second threshold value, the control logic unit operates the valve (20) to a second valve different from the first position, and in this abnormal operation mode (26), open-loop control and closed-loop control by the compressor (4) are not executed. Preferably, in this abnormal operation mode (26), open-loop control and closed-loop control by the expansion device (6) are also not executed. gc) 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. A centrifuge (19) characterized by this.

2. ​ ​ ​ a) The valve (20) is a two-way solenoid valve (28) having a larger open position and a smaller open position, in particular a flow-through position and a shut-off position, b) The control logic unit has a control logic unit, - when the difference between the set temperature in the centrifuge bowl (3) and the temperature detected by the temperature sensor (23) is greater than a threshold value, the control logic unit operates the two-way solenoid valve (28) from the smaller open position to the larger open position, preferably, the control logic unit controls the two-way solenoid valve (28) from the smaller open position to the larger open position for a predetermined period. The centrifuge (19) according to claim 1, characterized in that. Claim 3 The centrifuge (19) according to claim 1 or 2, characterized in that the expansion device (6) is a passive thermostat-type injection valve (7). Claim 4 The centrifuge (19) according to any one of claims 1 to 3, characterized in that the compressor (4) is a rotary piston compressor (31). The valve has a plurality of different opening cross-sections, the control device has a control logic unit, - when the difference between the set temperature in the centrifuge bowl (3) and the temperature detected by the temperature sensor (23) is greater than a threshold value, the control logic unit increases the opening cross-section depending on the absolute value of the difference, the rate of change of the difference and / or the period during which the difference is greater than the threshold value. The centrifuge (19) according to claims 1, 3 and 4. Claim 6 The compressor (4) is continuously operated during the operation of the centrifuge (19), During the operation, the rotational speed always coincides with at least one minimum rotational speed. The centrifuge (19) according to any one of claims 1 to 5. Claim 7 A centrifuge (19) comprising a centrifuge bowl (3), a refrigerant circuit (1) having a circulating refrigerant, and a temperature sensor (23) for detecting a temperature at least correlated with the temperature in the centrifuge bowl (3), in particular a method for operating a continuous centrifuge, a centrifuge for biotechnology or a centrifuge for blood, The refrigerant circuit (1) has a controllable compressor (4), a condenser (5), an expansion device (6), and an evaporator (2) for cooling the centrifuge bowl (3). ​ ​ ​ ​ The connecting pipe (17) connecting the compressor (4) to the condenser (5) is connected to the connecting pipe (16) between the expansion device (6) and the evaporator (2) via a bypass pipe (15), An electronically controlled valve (20) for controlling the flow rate is arranged in the bypass pipe (15), The method is as follows, a) A method step of checking whether the difference between the set temperature in the centrifuge bowl (3) and the temperature detected by the temperature sensor (23) is greater than a threshold value, b) As a result of the inspection, when the difference is greater than the threshold value, a method step of increasing the flow rate flowing through the bypass pipe (15), c) It is inspected whether the absolute value of the difference between the set temperature in the centrifuge bowl (3) and the temperature detected by the temperature sensor (23) is smaller than the threshold value or a second threshold value, ca) When the absolute value of the difference is smaller than the threshold value or the second threshold value, the centrifuge (19) is operated in a normal operation mode (21). In this normal operation mode (21), while the valve (20) is in the first position, open-loop control and / or closed-loop control by the expansion device (6) and / or the compressor (4) is executed, cb) When the absolute value of the difference is not smaller than the threshold value or the second threshold value, the centrifuge (19) is operated in an abnormal operation mode (26). In this abnormal operation In the mode (26), the valve (20) is operated to a second valve different from the first position. In this abnormal operation mode (26), open-loop control and / or closed-loop control by the compressor (4) is not executed. Preferably, in this abnormal operation mode (26), open-loop control and / or closed-loop control by the expansion device (6) is also not executed, In the first position of the valve (20), the opening cross-sectional area of the valve (20) is smaller than the opening cross-sectional area of the valve (20) in the second position.

8. The method according to claim 7, characterized in that the flow rate of the refrigerant flowing through the evaporator (2) is controlled in an open loop or a closed loop by a passive thermostatic injection valve (7).

9. In the refrigerant circuit (1), the method according to claim 7 or 8, characterized in that the refrigerant flows out by a rotary piston compressor (31).

10. a) The valve (20) is controlled to have a plurality of different opening cross-sectional areas, b) It is inspected whether the difference between the set temperature in the centrifuge bowl (3) and the temperature detected by the temperature sensor (23) is greater than a threshold value, The method according to any one of claims 7 to 9, characterized in that when the difference is greater than the threshold value, the opening cross-section is enlarged depending on the absolute value of the difference, the rate of change of the difference and / or the period during which the difference is greater than the threshold value.

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

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

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