Centrifugal machine and method for operating the same

Abstract

To reduce fluctuation in rotor temperature, preventing a reactivation failure, by changing the shortest holding time of the stop state of a motor for a compressor in accordance with an ambient temperature in a centrifugal machine.SOLUTION: This centrifugal machine comprises: a temperature sensor 5 for a rotor chamber 4, which measures a temperature in the rotor chamber; and an ambient temperature sensor 13 that measures a temperature around a condenser 11b. A control device 8 performs on / off control for stopping a drive motor for a compressor 11a when the temperature in the rotor chamber reaches a stop temperature threshold and activating the drive motor for the compressor 11a when the temperature in the rotor chamber reaches a reactivation temperature threshold after a stop time threshold is exceeded. In this case, the threshold (shortest holding time) of the stop time of the compressor 11a is changed in accordance with the measured ambient temperature.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a technique for shortening the time from stopping to restarting a compressor that is on / off controlled in a centrifuge that rotates a rotor. [Background technology]

[0002] In a centrifuge, samples in tubes or bottles are held in a rotor, and the rotor, which is set in a crown inside a chamber, is rotated at high speed, causing substances with high density to precipitate out due to centrifugal force, and separating the samples. During this process, the centrifuge's control device accelerates the rotor for a short period of time, rotates it at a constant high speed for a set period of time, and then decelerates it. During centrifugation operation, the rotor chamber is cooled and kept at a low temperature (e.g., 4°C), thereby maintaining the samples held in the rotor at a constant low temperature.

[0003] In order to cool the rotor chamber, a cooling pipe is provided around the bowl forming the rotor chamber, and a refrigerator using a compressor is used. In early refrigerators, the rotation speed of the compressor motor was set to a single rotation speed that depended on the power supply frequency, and temperature control was performed by controlling the on and off of the compressor motor. Current refrigerators often use variable speed compressors controlled by inverters, and the rotation speed of the compressor motor is increased or decreased according to the required cooling capacity. However, after the temperature inside the rotor chamber is cooled to a set temperature, depending on the type of rotor and the ambient temperature, the cooling capacity may be too high even at the minimum operable rotation speed of the compressor motor. In that case, the compressor motor is not controlled only by variable speed operation, but is instead operated intermittently by repeatedly turning on and off the compressor motor, a so-called "on-off operation."

[0004] When the compressor motor is temporarily stopped from an operating state, there is a pressure difference between the high pressure side and the low pressure side of the cooling system, so there are cases where the chiller motor cannot be restarted unless time is allowed for the pressure difference to become equal to or less than a predetermined value. When the compressor motor is controlled on and off in a conventional centrifuge, it takes a predetermined time (e.g., 2 minutes) from when the compressor motor stops until it is restarted, making it difficult to perform fine temperature control by controlling the intermittent operation of the refrigerator. For this reason, in Patent Document 1, a restriction is set in which the compressor motor is started after a certain period of stop time has elapsed, with a time value as the restart prohibition section. This is because, for reasons of oil lubrication of the compressor, it cannot be turned on until the pressure difference between the suction pipe and the discharge pipe becomes equal to or less than a predetermined value, and it is necessary to turn it off when the pressure difference is equal to or more than a predetermined value. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-228400 Summary of the Invention [Problem to be solved by the invention]

[0006] Even when a variable speed compressor as in the cited document 1 is used, temperature control cannot be performed by continuous variable speed operation alone, and intermittent on / off operation of the variable speed compressor may be required. The rotor temperature fluctuates around the set temperature due to the influence of on / off control of the refrigerator, but the fluctuation can be reduced by increasing the frequency of on / off control. However, the compressor, which is one of the components of the refrigerator, will cause startup problems if it is not started after a certain period of time has passed since it was stopped. Therefore, it is essential to set a minimum stop state retention time and control the refrigerator so that it is stopped for at least that period of time before restarting.

[0007] In conventional centrifuges, the shortest hold time for the compressor motor to be stopped is set to a constant value regardless of the environmental temperature (ambient temperature) in which the refrigerator is placed. In this case, it was necessary to set the shortest hold time so that the compressor motor would not malfunction even when the ambient temperature was at the upper limit of the guaranteed operating temperature. On the other hand, when the compressor motor is turned on and off using the shortest hold time set in this way, the compressor motor is kept stopped longer than necessary when the ambient temperature is low, which is one of the factors that causes large fluctuations in the rotor temperature. Similarly, for the rotor, the shortest hold time is set according to the rotor that needs to be kept stopped for the longest time (usually the rotor with the largest windage loss) so that the compressor motor will not malfunction no matter what rotor is installed. Therefore, the stop state is set longer than necessary for rotors other than the rotor with the largest windage loss, causing large fluctuations in the rotor temperature.

[0008] The present invention has been made in view of the above-mentioned background, and has an object to realize a centrifuge that reduces fluctuations in rotor temperature while avoiding startup failure by changing the minimum time for which the compressor motor is held stopped in accordance with the ambient temperature of the compressor.

[0009] Another object of the present invention is to realize a centrifuge that reduces fluctuations in rotor temperature while avoiding startup failure by changing the minimum time for which the compressor motor is held stopped in accordance with the type of rotor installed. [Means for solving the problem]

[0010] Representative features of the invention disclosed in this application are as follows. According to one feature of the present invention, there is provided a centrifuge having a rotor, a bowl forming a rotor chamber that houses the rotor, a drive unit that drives the rotor to rotate, a refrigerator that cools the rotor chamber, and a control device that controls the operation of the drive unit and the refrigerator, the refrigerator including a compressor that compresses a refrigerant, a motor that drives the compression, a condenser that condenses the compressed refrigerant, and an evaporator provided on the outer periphery of the rotor chamber. The centrifuge is also provided with a rotor chamber temperature sensor that measures the temperature of the rotor chamber, and an ambient temperature sensor that measures the temperature around the condenser. The centrifuge control device detects when the temperature of the rotor chamber during centrifugation operation reaches a stop temperature threshold T off When the temperature of the rotor chamber reaches the start temperature threshold T, the compressor motor is stopped. on When the temperature reaches the ambient temperature, the control device changes the length of the stop time threshold during the centrifugation operation in accordance with the ambient temperature measured by the ambient temperature sensor.

[0011] According to another feature of the present invention, the ambient temperature sensor of the centrifuge is provided inside the housing that houses the rotor chamber, the drive unit, and the refrigerator, at a position exposed to air taken in from outside the housing and reaching the evaporator. The stop time threshold set by the control device is set according to the type of rotor arranged in the rotor chamber. In particular, the stop time of the compressor motor is set to be short when the ambient temperature is low, and is set to be lengthened stepwise or continuously as the temperature rises. The control device is configured to include a processor and a storage unit, and the storage unit stores in advance a setting criterion for the stop time threshold for the ambient temperature for each rotor to be mounted. The setting criterion for the stop time threshold for the ambient temperature can be configured to be stored, for example, as a list of multiple stop time thresholds for each ambient temperature range, or as a function formula for calculating the stop time threshold with the ambient temperature as a variable.

[0012] According to yet another feature of the present invention, in a centrifuge having a bowl forming a rotor chamber that houses a rotor, a refrigerator that supplies refrigerant to an evaporator through a cooling pipe wound around the outer periphery of the bowl, and a control device that controls the operation of a drive unit of the rotor and the refrigerator, a rotor chamber temperature sensor that measures the temperature of the rotor chamber and an ambient temperature sensor that measures the temperature around the refrigerator are provided. The control device detects when the temperature of the rotor chamber exceeds a stop temperature threshold T off When the temperature of the rotor chamber reaches the start temperature threshold T, the operation of the refrigerator is stopped. After the stop time threshold set for each rotor has elapsed, on When the ambient temperature rises to 100° C., the refrigerator is restarted. The control device monitors the output from the ambient temperature sensor while the refrigerator is in operation, and changes the stop time threshold when there is a change in the ambient temperature. The change in the stop time threshold is preferably controlled so as to update the stop time threshold when the compressor motor of the refrigerator is in operation. Effect of the Invention

[0013] According to the present invention, since the length of the stop time threshold is adjusted according to the ambient temperature, the stop time of the refrigerator can be shortened when the ambient temperature is low, and the fluctuation of the rotor temperature can be reduced. In addition, by lengthening the stop time of the refrigerator when the ambient temperature is high, the occurrence of start-up failure can be avoided, which leads to a reduction in the risk of component failure. Furthermore, since the occurrence of start-up failure is also influenced by the rotor being used, a centrifuge that minimizes fluctuation of the rotor temperature can be realized by changing the minimum time for which the stopped state is maintained depending on the rotor. [Brief description of the drawings]

[0014] [Figure 1] 1 is a vertical sectional view showing an entire centrifuge 1 according to an embodiment of the present invention. [Diagram 2] 2 is a flowchart showing a control procedure for the refrigerator 11 in FIG. [Diagram 3] 2 is a diagram showing a setting screen 50 of the operation display unit 3 of FIG. 1. [Figure 4]2 is a diagram showing an example of a rotor information table 70 prestored in the storage unit 8b of FIG. 1. FIG. [Diagram 5] 1 is a graph showing rotor temperature fluctuations and refrigerator on / off time changes of a centrifuge 1 according to an embodiment of the present invention (part 1). [Figure 6] 2 is a graph showing rotor temperature fluctuations and refrigerator on / off time changes of the centrifuge 1 according to the embodiment of the present invention (part 2). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following drawings, the same parts are given the same reference numerals, and repeated explanations will be omitted. In addition, in this specification, the up, down, left and right directions will be described as the directions shown in FIG.

[0016] FIG. 1 is a cross-sectional view showing the overall structure of a centrifuge (centrifuge) 1 according to an embodiment of the present invention. In the centrifuge 1, a bowl 4a formed of a thin metal plate is provided inside a box-shaped housing 2 made of sheet metal or the like, and a rotor chamber 4 is defined by the bowl 4a and a door 10. One side of the door 10 is supported by the housing 2 and can be opened and closed about a rotation axis. The rotor 6 holds the sample to be separated and rotates at high speed. For example, a plurality of holes (not shown) are formed for inserting tubes or the like for containing the sample, and the rotor 6 is supported by a rotating shaft of a drive unit 9 such as a motor. The rotor 6 is rotated by the drive unit 9, and the rotation of the drive unit 9 is controlled by a control device 8. To the right of the door 10, an operation display unit 3 is arranged, through which the user inputs conditions such as the rotor rotation speed and separation time, and on which various information is displayed. The operation display unit 3 employs a so-called dot matrix display device, and here employs a touch-type display, which functions as an operation means (input means) for inputting the operating conditions, rotation start and stop of the centrifuge 1, and also functions as an output means that can display to the user the operating state of the centrifuge 1. The operation display unit 3 may be realized by a liquid crystal or organic EL touch-type display, or may be realized by a combination of a liquid crystal or organic EL display means (display only) and an input means such as a button, key, or mouse device.

[0017] The rotor chamber 4 is configured so that the opening on the upper side can be sealed by a door 10, and the rotor 6 can be attached or removed inside the rotor chamber 4 with the door 10 open. In the centrifuge 1, some samples to be separated while being maintained at a low temperature, and in such cases, the control device 8 operates the refrigerator 11 to perform centrifugation while cooling the rotor chamber 4. To configure the refrigerator 11, an evaporator 11c is formed by winding cooling piping such as a copper pipe in a spiral shape around the outer periphery of the bowl 4a. The outer periphery of the evaporator 11c is surrounded by a cylindrical heat insulating material (not shown).

[0018] In the lower space of the housing 2, a compressor 11a and a condenser 11b constituting the refrigerator 11 are arranged. The evaporator 11c is connected to a pipe from the compressor 11a (input side) and to a pipe to the condenser 11b (output side). In addition, a blower (not shown) is installed on the rear of the main body to dissipate heat from the condenser 11b, and takes in air from an intake port (not shown) opened at the bottom of the front of the main body and exhausts it from an exhaust port (not shown) on the rear. In the refrigerator 11, the refrigerant is sent from the compressor 11a to the condenser 11b, and the cooled refrigerant is liquefied by the condenser 11b and the blower (not shown). The liquefied refrigerant is supplied to the cooling pipe (evaporator 11c) through a capillary (not shown), and the inside of the rotor chamber 4 is cooled by removing heat from the bowl 4a in contact with the evaporator 11c as the cooling medium evaporates. During the centrifugation operation, the rotor chamber 4 is kept constant at a desired set temperature under the control of the control device 8. A rotor chamber temperature sensor 5 is used on the inner bottom surface of the rotor chamber 4, and its output is input to a control device 8, which controls the operation of a compressor motor (not shown) that drives the compressor 11a so that the internal temperature of the rotor chamber 4 becomes the set temperature.

[0019] The control device 8 is configured with a microcomputer and a storage unit (not shown), and controls each device, including the rotation of the drive unit 9 and the refrigerator 11, by executing a computer program. The storage unit 8b of the control device 8 includes volatile and non-volatile memories (not shown), and the relationship between the identification information, model numbers, and allowable rotation speeds of the multiple rotors 6 is stored in the non-volatile memory. These are stored in the storage unit 8b in advance when the centrifuge 1 is shipped, or are stored or updated after shipping. An ambient temperature sensor 13 is provided inside the housing 2 of the centrifuge 1 and above the partition plate 2a. The output of the ambient temperature sensor 13 is input to the control device 8, so that the control device 8 can detect the ambient temperature. Here, the "ambient temperature" refers to the temperature of the environment in which the refrigerator 11 operates, and is mainly the temperature of the internal space of the housing 2. The temperature of this internal space is also affected by the external air temperature, since external air is constantly introduced into the housing 2 by a blower (not shown) to dissipate heat from the refrigerator 11. The ambient temperature sensor 13 may be installed not only in the upper part of the partition plate 2a, but also near an intake port (not shown) at the bottom of the housing 2, and may also be adapted to measure the outside air temperature around the centrifuge 1.

[0020] The rotor 6 installed in the rotor chamber 4 is selected by the user according to the sample container to be rotated, and is attached to the rotation axis of the drive unit 9. A rotor identifier 7 is attached to the bottom surface of the rotor 6 by a known method, and the rotor identifier 7 is read by a rotor identification device 12 provided near the rotation axis. The identification information attached to the rotor identifier 7 defines a plurality of lattice points defined at equal intervals on the circumference of the bottom surface of the rotor 6, centered on the rotation axis, and the rotor identification device 12 detects whether or not a magnet (not shown) is present on each lattice point, and the control device 8 decodes the coded identification information from the detection interval of the magnet. A rotor identification device 12 that detects the presence or absence of a magnetic field caused by a magnet (not shown) is provided at a portion of the rotor 6 facing the rotor identifier 7. The rotor identification device 12 is composed of a magnetic sensor such as a Hall IC. The output of the rotor identification device 12 is transmitted to the control device 8 by a signal line (not shown). The control device 8 reads the identification information by detecting the magnetic field caused by the magnet by the rotor identification device 12 immediately after the rotor 6 starts to rotate. This identification information may include the rotor model number, serial number, and the like.

[0021] As described above, the control device 8 controls the entire centrifuge 1, and includes a processor 8a capable of executing computer programs, and a storage unit 8b. The operation of the control device 8 is performed by the processor 8a executing a computer program that realizes a specific function. In the centrifuge 1 of this embodiment, an ambient temperature sensor 13 is provided to detect the ambient temperature of the refrigerator 11, and a control program that changes the minimum time for which the compressor 11a of the refrigerator 11 is stopped according to the detected ambient temperature is stored in advance in the storage unit 8b of the control device 8. The processor 8a controls the rotation control of the drive unit 9 and also controls the operation of the compressor 11a.

[0022] The compressor operation control by the processor 8a includes on / off control of the compressor 11a. In this embodiment, the hold time from when the compressor 11a is turned off until it is turned on again is not a fixed value, but is changed according to the ambient temperature at that time. That is, the minimum hold time X of the compressor 11a in the off state is set to be shorter the lower the ambient temperature is, and longer the higher the ambient temperature is. To enable this control, an ambient temperature sensor 13 is installed inside the centrifuge 1 to detect the temperature inside the centrifuge 1, and the difference between the temperature inside the centrifuge 1 and the temperature (outdoor temperature) of the place where the centrifuge 1 is installed is obtained in advance by experiment or the like, and the optimum minimum hold time X for each rotor is calculated.

[0023] Fig. 2 is a flowchart showing the control procedure of the refrigerator 11 of the centrifuge 1 according to the embodiment of the present invention. The control of the flowchart in Fig. 2 is realized by the processor 8a (see Fig. 1) executing a computer program that controls this embodiment, and when a user turns on the power of the centrifuge 1, a program previously stored in the storage unit 8b is read and executed. Note that a computer program that manages the entire centrifuge 1 is also read from the storage unit 8b and executed in parallel by the processor 8a, but since the computer program for managing the entire operation is similar to a known program, a description thereof will be omitted here.

[0024] Before performing centrifugation, the user sets the rotor 6 in the rotor chamber 4 and closes the door 10. Next, the user inputs the conditions for the centrifugation operation using the operation display unit 3 (step 31). An example of the display on the operation display unit 3 at this time is shown in FIG. 3. FIG. 3 shows a setting screen 50 on the operation display unit 3 when step 31 is performed. This display screen is in a state immediately after the operating conditions of the centrifuge 1 are set (before the start button is pressed). The setting screen 50 displays the operating state and operating conditions (set values) of the centrifuge 1, and includes a rotation speed display area 51, an operating time display area 54, and a temperature display area 57, which are the operating conditions of the centrifuge. Around these areas, a rotor type display section 60 indicating the type of the set rotor 6, an ACCEL display section 61 indicating the acceleration of the rotor 6, and a DECEL display section 62 indicating the deceleration of the rotor 6 are provided. A start button 63 displayed as an icon to instruct the start of the centrifugation operation, and an open button 64 for opening the door 10 are displayed on the lower right part of the setting screen 50.

[0025] The rotation speed display area 51 displays information related to the rotation speed of the rotor 6. The large number "0" in the center indicates the current rotation speed 52 of the rotor 6, and the number following "SET" below it is the set rotation speed 53 input (SET) by the user. In this example, 18,000 revolutions per minute (rpm) is set as the set rotation speed 53 for centrifugation. When the user touches any position within the frame of the rotation speed display area 51 with his / her finger, a numeric keypad screen (not shown) pops up and the user can input the set rotation speed 53 by operating the numeric keypad.

[0026] The operation time display area 54 displays information regarding the operation time of the rotor 6, and the large number in the center is the actual operation time (elapsed time) 55 during which the rotor 6 is operated at the set rotation speed 53, and is displayed in units of minutes, seconds, or hours and minutes. In FIG. 3, the rotor 6 is not yet rotating because it is in a state before centrifugation is performed, and the operation time 55 is displayed as 00 minutes and 00 seconds. The operation time 55 is automatically counted and displayed using a timer function included in the processor 8a of the control device 8. The number following "SET" below the operation time 55 is the time for centrifugation input by the user, that is, the set operation time 56, and in this example, it shows a state in which 25 minutes and 00 seconds is set. As with the rotation speed display area 51, when the user touches the frame of the operation time display area 54 with his / her finger, a numeric keypad screen (not shown) pops up and the user can input the operation time by operating the numeric keypad.

[0027] The temperature display area 57 displays information related to the temperature inside the rotor chamber 4, with the large letters in the center being the current temperature 58 of the rotor chamber 4 and the number following "SET" below it being the set temperature 59 of the rotor 6 to be maintained when performing centrifugation. In FIG. 3, the current temperature 58 is 20.0°C and the set temperature is 4.0°C. As with the rotation speed display area 51, when the user touches the inside of the frame of the temperature display area 57 with their finger, a numeric keypad screen (not shown) pops up and the user can input the set temperature 59 by operating the numeric keypad.

[0028] The rotor type display section 60 displays the model name of the rotor 6 to be operated, and in Fig. 3, "T18A41" which is the model number of the rotor 6 is displayed. The rotor 6 may be set by the user touching the rotor type display section 60 to display a rotor list screen (not shown) and selecting from the list, or the rotor 6 itself may have information so that when the rotor 6 is set in the centrifuge 1, the rotor model number is automatically identified on the centrifuge 1 side. The method for automatically identifying the rotor model number may be to attach an optical or magnetic ID code to the rotor, or any other known identification method may be used, so further explanation will be omitted here.

[0029] The start button 63 is a button for starting the operation of the centrifuge 1, and when the start button 63 is touched, the control device 8 accelerates the rotor 6 to the set rotation speed 53 set in the rotation speed display area 51, and rotates (settles) the rotor 6 at the set rotation speed 53. The open button 64 is a button for opening the door 10 of the centrifuge 1, and when the open button 64 is touched, a lock mechanism (not shown) of the door 10 is released. Note that while the rotor 6 is rotating, a stop button (not shown) for instructing to stop the centrifugation operation is displayed in place of the open button 64.

[0030] Return to FIG. 2 again. In step 31, when the input of the centrifugation operation conditions is completed, the user operates the start button (not shown) on the operation display unit 3. Then, the control device 8 starts the drive unit 9 to start the rotation of the rotor 6 (step 32). Note that the refrigerator 11 may be started before the rotor 6 starts to rotate, to cool the inside of the rotor chamber 4, and the rotor 6 may start to rotate after it has been cooled to the set temperature. When a rotary type variable speed compressor is used as the refrigerator 11, the cooling capacity can basically be adjusted by adjusting the rotation speed of the compressor 11a. However, even if the rotation speed of the compressor 11a is reduced to the minimum controllable rotation speed, there are cases where the cooling capacity is exceeded, and in such a case, the compressor 11a is stopped. After the compressor 11a is stopped, the rotor chamber temperature is set to a temperature lower than the start temperature threshold T on After waiting until the temperature reaches 100° C., the processor 8a controls the compressor 11a to restart.

[0031] When the rotor 6 starts to rotate, the control device 8 detects the identification information of the rotor 6 using the rotor identification device 12. This detection is performed in a low-speed acceleration region immediately after the motor is started, for example, at a rotation speed of about tens to hundreds of rpm. Some centrifuges can detect the rotor ID when the rotor 6 is simply installed inside the rotor chamber 4 and is not rotating. In this embodiment, however, the arrangement pattern of the multiple permanent magnets attached to the rotor 6 is detected above the rotor identification device 12, so that the condition for detecting the rotor ID is that the rotor 6 is rotating at a low speed. If there is identification information (model information, serial number, etc.) of the rotor 6 that has already been input by the user, the control device 8 compares whether the identification information input by the user matches the identification information detected by the rotor identification device 12. Although this comparison step is not shown in FIG. 2, if there is a mismatch, the centrifugation operation is interrupted and the user is prompted to correct the input identification information. If the identification information matches, the control device 8 increases the rotation speed of the rotor 6 and rotates it at the set rotation speed. 2 shows the control procedure of the refrigerator 11, the procedure for controlling the rotation of the drive unit 9 is not described.

[0032] The control device 8 detects the temperature inside the rotor chamber 4 by the rotor chamber temperature sensor 5 at regular detection intervals, and detects the ambient temperature by the ambient temperature sensor 13 (step 34). Next, the control device 8 sets the shortest hold time X of the compressor 11a according to the detected ambient temperature. To perform this setting, the relationship between the type of rotor 6 and the shortest hold time X is stored in the memory unit 8b of the control device 8. Here, an example of a method of storing the shortest hold time X is shown with reference to FIG. 4.

[0033] FIG. 4 shows a rotor information table 70 that stores the relationship between the type of rotor 6 and the shortest retention time X. The rotor information table 70 stores a rotor type (manufacturer's control number or control number in the storage unit 8b) 71, a serial number (unique number of the rotor 6 that corresponds one-to-one with the rotor type 71) 72, and various information 73 for controlling the centrifugation operation associated with them, and stores a shortest retention time X 74 for each temperature range according to this embodiment in addition to them. The information 73 includes information required for the rotation control of the rotor 6 by the control device 8, such as the maximum usable rotation speed (maximum allowable rotation speed) of the rotor 6 shown in the rotor type 71, the maximum usable number of times of the rotor 6 (operation number life specification), and the accumulated usable time of the rotor 6 (operation time life time). These pieces of information are specifications specified by the manufacturer of the rotor 6, and are stored in advance in the storage unit 8b (see FIG. 1) at the time of shipping the centrifuge 1. In addition, the information 73 can be added manually after shipping, and can also be automatically added via a network. It should be noted that the information 73 may include other information in addition to the above examples, but the description thereof will be omitted.

[0034] In the shortest retention time X74 field, the ambient temperature zones are divided into four zones, and the minimum permissible retention time from stopping to restarting the compressor 11a in each temperature zone, that is, the shortest retention time X, is stored. Here, the ambient temperature assumed by the ambient temperature sensor 13 (see FIG. 1) is divided into four temperature zones 74a to 74d, namely, less than 10°C, 10°C to less than 20°C, 10°C to less than 20°C, and 30°C or more, and the shortest retention time X (unit: seconds) in each temperature zone is stored as shown in the example of FIG. 4. As described above, the shortest retention time X74 for each temperature zone is stored in advance in the memory unit 8b (see FIG. 1), so the processor 8a can read out these values ​​and operate the compressor 11a.

[0035] Returning to FIG. 2 again, in step 34, processor 8a (see FIG. 1) of control device 8 detects the temperature of rotor 6 (rotor temperature) from the output of rotor chamber temperature sensor 5, and further detects the ambient temperature from the output of ambient temperature sensor 13 (see FIG. 1). Processor 8a reads out from memory unit 8b the shortest hold time X (any of 71 to 74) corresponding to the ambient temperature based on the detected ambient temperature and from the table in FIG. 4, and sets it as the shortest hold time X to be used in subsequent control (step 35). It is also possible to configure so that shortest hold time X is found by an arithmetic formula, and for example, the following approximation formula for the data of the AA123 rotor in FIG. 4 is X = r + 50 (Equation 1) Where, X is the minimum holding time, and r is the ambient temperature. The above (Formula 1) may be stored in the shortest retention time X74 field.

[0036] Next, the processor 8a waits until the shortest hold time X set in step 35 has elapsed (step 36). When the shortest hold time X has elapsed, the processor 8a again measures the rotor chamber temperature from the output of the rotor chamber temperature sensor 5 (step 37). If the rotor chamber temperature is equal to or lower than the start-up temperature T on It is determined whether the rotor chamber temperature has risen to the start temperature T (step 38). on If it has not risen to the start temperature T on Steps 37 and 38 are repeated until the rotor chamber temperature rises to the starting temperature T on When the temperature of the rotor chamber reaches the stop temperature T, the compressor 11a of the refrigerator 11 is started (step 39). When the compressor 11a is started, the processor 8a measures the rotor chamber temperature of the centrifuge 1 during operation (step 40). off It is determined whether the rotor chamber temperature has decreased to the stop temperature T (step 41). off If the rotor chamber temperature does not drop to the stop temperature T off If the temperature drops to , the processor 8a stops the operation of the motor of the compressor 11a of the refrigerator 11 (step 42), and the process returns to step .

[0037] As described above, in this embodiment, the processor 8a detects the ambient temperature during centrifugal separation operation, and when the refrigerator 11 is stopped, waits until the shortest retention time X corresponding to the ambient temperature has elapsed, and then restarts the compressor 11a as soon as the conditions for restarting the refrigerator 11 are satisfied. This control state will be described with reference to Figures 5 and 6.

[0038] 5 is a graph showing rotor chamber temperature 81 and compressor operating state 85 over time. The upper graph shows rotor chamber temperature 81 detected by rotor chamber temperature sensor 5, with the horizontal axis representing time (unit: seconds) and the vertical axis representing temperature (unit: °C). This graph shows a rotor that needs to be kept stopped for the longest period of time, and where the ambient temperature is lower than the average room temperature (e.g., 25 °C) at which the centrifuge is used.

[0039] The lower graph shows the operating state 85 of the compressor 11a, with the horizontal axis being time (unit: seconds) and the vertical axis being high when the motor (not shown) of the compressor 11a rotates, and low when it is off. The horizontal axes of the upper and lower graphs are illustrated in a synchronized state. The motor (not shown) for the compressor 11a is controlled by the control device 8 to be driven at a constant speed, or is controlled at a variable speed according to the required cooling capacity. The speed control of the rotary compressor using inverter control is well known in the field of the refrigerator 11, so a detailed description is omitted here. However, if the temperature continues to decrease even when the rotation speed of the motor (not shown) for the compressor 11a is minimized, the processor 8a of the control device 8 performs an operation to stop the refrigerator 11, i.e., stops the motor for the compressor 11a, for example, at times t2 and t4.

[0040] As shown in the upper graph, the temperature of the rotor chamber 4 (rotor chamber temperature 81) in the centrifuge 1 is equal to or higher than the temperature T SET(for example, 4°C as shown in FIG. 3). For this reason, the operation of the refrigerator 11 is controlled according to the type of rotor 6 being used. When performing on-off control to operate the refrigerator 11 intermittently, a control program for changing the minimum holding time X for which the compressor 11a is stopped is stored in advance in the memory unit 8b of the control device 8 and executed by the processor 8a. When the rotor 6 is rotating at high speed within the rotor chamber 4, the temperature of the rotor 6 rises due to windage loss of the rotor 6. Therefore, when the compressor 11a is stopped, the temperature within the rotor chamber 4 drops to the set temperature T at time 0. SET At time t1, the start temperature threshold T on to reach.

[0041] At time t1, the rotor chamber temperature 81 reaches the start temperature threshold T on When the set temperature T is reached, the processor 8a restarts the compressor 11a, as shown in the operating state 85 of the compressor 11a. When the compressor 11a starts up, as shown by the rotor chamber temperature 81 in the graph above, after a time delay due to the cooling effect of the compressor 11a occurs, the rotor chamber temperature 81 starts to gradually decrease from the point of arrow 81a. After that, the rotor chamber temperature 81 drops to the set temperature T SET In the normal on / off control of the compressor 11a, the processor 8a detects that the rotor chamber temperature 81 is equal to or lower than the set temperature T SET Slightly lower than the shutdown temperature threshold T off When the pressure reaches the pressure, the rotation of the motor of the compressor 11a is stopped.

[0042] At time t2, the compressor 11a stops, and after a time delay, the rotor chamber temperature 81 starts to gradually rise from the point of time indicated by the arrow 81b. After that, the rotor chamber temperature 81 rises to the set temperature T SET Then, the temperature rises again to the same state as at time 0, and the rotor chamber temperature 81 again exceeds the start temperature threshold T on After that, the processor 8a repeatedly stops and starts the motor of the compressor 11a so as to repeat the states from time t1 to time t3, and the rotor chamber temperature 81 reaches the temperature TSET The fluctuation range 82 of the rotor chamber temperature 81 during this control is as shown in FIG.

[0043] When performing such on / off control of the compressor 11a, it is important that the processor 8a turns the compressor 11a to the on state after the shortest hold time X has elapsed after turning the compressor 11a to the off state. This is because, in the case of the refrigerator 11 using the compressor 11a, once the compressor 11a is stopped, the compressor 11a cannot be restarted until the pressure difference between the high pressure side and the low pressure side of the cooling system becomes equal to or less than a predetermined value. Therefore, a threshold value of a predetermined time (e.g., 120 seconds) is set from when the compressor 11a is stopped until the compressor 11a can be restarted. Since the time until the pressure difference becomes equal to or less than a predetermined value varies depending on the ambient temperature and the type of rotor 6 used, the processor 8a stores the shortest hold time X for each ambient temperature and each rotor in the rotor information table 70 shown in FIG. 4, and changes it each time depending on the ambient temperature during the operation of the centrifuge and the rotor 6 used. It is preferable to make this change when the motor of the compressor 11a is on.

[0044] FIG. 6 shows control in the case where the rotor needs to be kept stopped for the longest time and the ambient temperature is higher than the average room temperature (e.g., 25° C.) where the centrifuge is used. As can be seen by comparing with the graph of the rotor chamber temperature 81 in FIG. 5, the fluctuation range 92 of the graph of the rotor chamber temperature 91 in FIG. 6 is larger than the fluctuation range 82 of the rotor chamber temperature 81 in FIG. 5, and the period of the fluctuation is also longer. In general, when the ambient temperature is high, if the stopped state is not kept for a long time, a start-up failure is likely to occur, so the minimum holding time needs to be set to a long time so that a start-up failure does not occur. In this embodiment, the holding time X can be optimized according to the ambient temperature, so that when the ambient temperature is high, a long minimum holding time X can be set, such as the stop time 93, and when the ambient temperature is low, the minimum holding time X can be set to a shorter time than before, such as the stop time 83 in FIG. 5.

[0045] As described above, in this embodiment, when the ambient temperature is low, it is possible to set the stop time of the compressor 11a shorter than in the past, and it is possible to reduce the fluctuation of the rotor chamber temperature 81 compared to the conventional centrifuge. Conversely, when the ambient temperature is high, the stop time of the refrigerator is the same as the stop time (fixed value) assuming the worst case as performed in the conventional device, but it is possible to reliably avoid the occurrence of start-up failure of the compressor 11a, which leads to a reduction in the risk of component failure.

[0046] The present invention is not limited to the above-mentioned embodiment, and various modifications are possible within the scope of the present invention. For example, in the rotor information table 70 of FIG. 4, the range of the ambient temperature is divided into four, and the stop time X is set for each. This division is not limited to four, and may be reduced to two or three, or may be divided into five or more. Also, one stop time X may be changed according to the type of rotor to be mounted regardless of the temperature. In the present invention, since it is sufficient to set an optimal stop time X that changes depending on the ambient temperature, a function formula of the stop time X with the ambient temperature as a variable may be set for each rotor and stored in the rotor information table 70 in advance, and the stop time X may be calculated for each rotor 6 using the function formula. Furthermore, when the main power supply of the centrifuge 1 is turned off and then turned on after a sufficient time has passed, the control device 8 may be configured to immediately start the compressor 11a only the first time. [Explanation of symbols]

[0047] 1 Centrifuge 2 Housing 2a Partition plate 3 Operation display unit 4 Rotor chamber 4a Bowl 5 Temperature sensor for rotor chamber 6 rotor 7 rotor identifier 8 control device 9 Drive unit (rotor motor) 10 Door 11 Refrigeration unit 11a Compressor 11b Condenser 11c Evaporator 12 Rotor identification device 13 Ambient temperature sensor 50 Setting screen 51 Rotation speed display area 52 Rotation speed 53 Set rotation speed 54 Operation time display area 55 Operation time 56 Set operation time 57 Temperature display area 58 (Current) temperature 59 Set temperature 60 Rotor type display section 61 ACCEL display section 62 DECEL display 63 START button 64 OPEN button 70 Rotor information table 71 Rotor type 72 Serial number 73 Various information 74 Minimum holding time 74a~74d Temperature range 81, 91 Rotor chamber temperature 82, 92 Fluctuation range 83, 93 Stop time 85, 95 (Compressor) operating condition T on Start temperature threshold T off Shutdown temperature threshold T SET Set temperature

Claims

1. A centrifuge having a rotor, a bowl forming a rotor chamber for accommodating the rotor, a drive unit for driving the rotor to rotate, a refrigerator for cooling the rotor chamber, and a control device for controlling operation of the drive unit and the refrigerator, The refrigerator includes a compressor that compresses a refrigerant, a motor that drives the compression, a condenser that condenses the compressed refrigerant, and an evaporator that is provided on the outer periphery of the rotor chamber, a rotor chamber temperature sensor for measuring the temperature of the rotor chamber and an ambient temperature sensor for measuring the temperature around the condenser; The control device includes: performing on-off control to stop driving the motor when the temperature of the rotor chamber reaches a stop temperature threshold, and to resume driving the motor when the temperature of the rotor chamber reaches a start temperature threshold after a stop time threshold has elapsed; A centrifuge comprising: a stop time threshold value that is changed in length in response to an ambient temperature measured by the ambient temperature sensor.

2. 2. The centrifuge according to claim 1, wherein the ambient temperature sensor is provided inside a housing that houses the rotor chamber, the drive unit, and the refrigerator, at a position where the ambient temperature sensor is exposed to air that is taken in from outside the housing and reaches the condenser.

3. 3. The centrifuge according to claim 2, wherein the stop time threshold is set so that the stop time is short when the ambient temperature is low, and is set so that the stop time is lengthened stepwise or continuously as the temperature increases.

4. 4. The centrifuge according to claim 3, wherein the stop time threshold is set depending on the type of the rotor disposed in the rotor chamber.

5. The control device includes a processor and a storage unit, 5. The centrifuge according to claim 4, wherein the storage unit stores in advance a setting criterion for the stop time threshold value with respect to the ambient temperature for each rotor to be installed.

6. 6. The centrifuge according to claim 5, wherein the set criterion is a list of a plurality of the stop time thresholds for each range of ambient temperature, or a function formula for calculating the stop time threshold using the ambient temperature as a variable.

7. A method for operating a centrifuge having a rotor, a bowl forming a rotor chamber for accommodating the rotor, a drive unit for driving the rotor to rotate, a refrigerator for supplying a refrigerant to an evaporator through a cooling pipe wound around an outer periphery of the bowl, and a control device for controlling operation of the drive unit and the refrigerator, comprising the steps of: a rotor chamber temperature sensor for measuring the temperature of the rotor chamber and an ambient temperature sensor for measuring the temperature around the refrigerator are provided; The control device includes: When the temperature of the rotor chamber reaches a stop temperature threshold due to operation of the refrigerator, the operation of the refrigerator is stopped; After a stop time threshold set for each rotor has elapsed, when the temperature of the rotor chamber reaches a restart temperature threshold, the operation of the refrigerator is restarted by performing on / off control, A method for operating a centrifuge, comprising the steps of: monitoring an output from the ambient temperature sensor while the refrigerator is in operation; and changing the stop time threshold value when there is a change in the ambient temperature.

8. 8. The method for operating a centrifuge according to claim 7, wherein the stop time threshold is set for each rotor that is selected and installed, and the stop time is shortened when the ambient temperature is low, and is changed so as to become longer in a stepwise or continuously manner as the temperature increases.

9. The control device includes a processor and a storage unit, The storage unit stores in advance a setting criterion for the stop time threshold value with respect to an ambient temperature for each of the rotors to be installed, 9. The method for operating a centrifuge according to claim 8, wherein the control device, upon detecting a change in the ambient temperature, reads out the setting standard corresponding to the type of the rotor from the memory unit and updates the stop time threshold value.

10. 10. The method for operating a centrifuge according to claim 9, wherein the control device performs control so as to update the stop time threshold value during operation of the motor of the refrigerator when a fluctuation in the ambient temperature is detected.

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