JP5674236B2 - centrifuge - Google Patents

Description

  The present invention relates to a centrifuge having a cooling mechanism, and more particularly to a centrifuge that realizes a cooling mechanism capable of high-precision control while realizing a throttle mechanism used for temperature control at low cost.

The centrifuge stores a sample stored in a container such as a tube in a rotor, and performs centrifugation by rotating the rotor at a high speed in a rotating chamber. An electric motor is widely used as a driving device for rotating the rotor. When the rotor is rotated at high speed, the sample can be efficiently centrifuged. However, if the rotational speed of the rotor becomes too high, the temperature of the sample contained in the rotor rises due to the amount of heat (windage loss) generated by the air friction of the rotor. There is a fear. For example, in a centrifugal separator with a rotational speed of 5,000 min ^{−1 to} 30,000 min ⁻¹ class, a Carnot cycle cooling mechanism using a compressor is widely used to prevent the rotor temperature from rising. .

  In addition, biochemical samples that frequently use a centrifuge often have a property of being deactivated by temperature, and it is important to appropriately control the temperature of the sample during centrifugation. In the conventional centrifugal separator, it is generally performed to control the temperature of the rotor by intermittently operating the compressor. In this cooling mechanism, the most inexpensive fixed throttle mechanism capillary tube is often used, and the cooling capacity affected by the capillary tube is generally the most likely to cause a temperature rise, for example, the rotor with the highest rotational speed. Designed to suit the load of

JP-A-5-228400

The cooling mechanism of the centrifuge is usually designed to match the load of the rotor with the highest rotational speed. This is because, when cooling a high-speed rotor, it is more effective than cooling a low-speed rotor. This is because it is necessary to lower the temperature of the rotating chamber. In a cooling mechanism designed for a high-speed rotor, the evaporating temperature is low, so the throttle mechanism is set so that the pressure is low. Therefore, the refrigerant circulation amount and the cooling capacity of the cooling mechanism inevitably become low. On the other hand, a medium to low speed large rotor with a maximum rotational speed of 15,000 min ⁻¹ or less can be cooled even if the rotating chamber temperature is higher than that of the high speed rotor.

As an example, when a rotor having a diameter of about 215 mm is operated at 18,000 min ⁻¹ at an outside air temperature of 25 ° C., the windage loss is about 700 W, the rotating chamber air temperature during operation is −8 ° C., and the sample temperature is approximately When the rotor of approximately 340 mm in diameter is operated at 10,000 min ⁻¹ under the same room temperature and the same installation conditions, the rotating chamber air during operation is operated even though the windage loss exceeds 1,000 W. The temperature can be cooled to -8 ° C, and the sample temperature can be cooled to -3 ° C. This is because the rotor having a diameter of about 340 mm has a large surface area, and the windage loss per rotor unit surface area is small, so that the rotor can be sufficiently cooled even if the temperature difference from the rotating chamber air necessary for cooling is small. A windage loss of about 300 W is cooled by using the cooling capacity of the dry gas refrigerant in which the liquid temperature of the refrigerant evaporates because the evaporation temperature shifts slightly higher due to an increase in the windage loss load. Unlike the wet gas refrigerant, the temperature rises only by absorbing a small amount of heat and does not contribute to cooling of the rotor. Therefore, further increase in size or speed of large rotors rotating at medium and low speeds is difficult to respond as long as a fixed throttle mechanism such as a capillary tube set for high-speed rotors is used. It was.

  In order to solve this problem, if the throttle mechanism is matched to a medium- and low-speed large rotor and the evaporation temperature is set higher than that of the high-speed rotor, the cooling capacity will increase greatly even if the same compressor is used. It becomes possible to cool the windage loss of the rotor. On the other hand, when using a high-speed rotor, the evaporation temperature cannot be lowered, and there may be a problem of insufficient cooling. As a countermeasure, if an electronic expansion valve is used and the throttle amount of the throttle mechanism is made variable, the evaporation temperature is controlled to be high when using a medium to low speed large rotor, and the evaporation temperature is controlled to be low for a high speed rotor. Although possible, electronic expansion valves are expensive, leading to an undesirable increase in the cost of the centrifuge. Furthermore, even if a variable speed compressor is adopted, the compressor rotation speed is increased, and the refrigerant circulation rate is increased, the fixed throttle mechanism still requires a compressor with a larger maximum capacity and at the same time the required power increases. Since the coefficient of performance (cooling capacity KW ÷ cooling power consumption KW) decreases and becomes very uneconomical, it is difficult to adopt it as it is in consideration of the manufacturing cost.

  The centrifuge is configured to rotate the rotor at a high speed and cool the windage generated at that time by a cooling mechanism. The time required for the rotor to reach the maximum rotational speed is about 1 to 3 minutes, It is important to cool the rotating chamber from the low set temperature to a control temperature of the rotating chamber which is lower by several to tens of degrees. However, rapid cooling of the rotating chamber is difficult to achieve without an excessive compressor or condenser. Even if both the centrifuge and the rotor have been cooled in advance to the temperature intended by the user, in order to cool the rotating chamber temperature to the control temperature while cooling the windage loss of the rotor, the rotor is set to the set rotational speed. After reaching the temperature, it takes several minutes, during which the sample temperature in the rotor may rise. When the centrifuge is just turned on and the temperature of the rotating chamber starts at room temperature, and the rotor starts from room temperature, after the rotor reaches the set rotational speed, the temperature of the rotating chamber reaches the control temperature for 10 minutes to 15 minutes. It will take a minute. The problem is that if the throttle mechanism is made variable and the evaporation temperature is increased during the period when the cooling capacity is required from the evaporation temperature immediately after the start of operation, the cooling time lag can be reduced. Many of them use a fixed throttle mechanism, and even if the capacity of the compressor and condenser is sufficient, the evaporation pressure cannot be changed. Even if a variable speed compressor is adopted and the cooling capacity is temporarily increased, a fixed throttle mechanism matched to the high speed rotor requires a compressor with a larger maximum capacity as described above. Just uneconomical.

  In general centrifuges, the temperature of the rotating chamber is controlled by intermittent operation control of the compressor. In the case of a constant speed compressor, the cooling effect can be reduced only by reducing the cooling capacity by adjusting the air volume and water volume by adjusting the air volume and water volume, or by reducing the refrigerant circulation volume using an electronic expansion valve. However, since expensive devices such as a fan with variable air volume, an electric adjustment valve for cooling water, and an electronic expansion valve are required, the use of these devices leads to a significant increase in the cost of the centrifuge. In order to stop the cooling effect, there are methods such as bypassing the refrigerant to the evaporator and bypassing it to the compressor, or stopping the refrigerant in front of the evaporator, but bypassing the evaporator and returning it to the compressor In this case, the compressor sucks and compresses the refrigerant with a large amount of liquid, and there is a risk that the liquid is compressed in the cylinder and the discharge valve of the cylinder is destroyed. If the refrigerant is stopped in front of the evaporator, the refrigerant is not sucked into the compressor, so that the compressor is likely to rise in temperature and have a short life.

  Therefore, intermittent operation of the compressor is the simplest and cheapest in terms of mechanism, but once the compressor is stopped, the compressor cannot be restarted until the pressure difference between the high pressure side and the low pressure side of the compressor becomes small. When the windage loss of the rotor is large, the temperature of the rotating chamber may suddenly rise while the compressor is stopped, and the temperature control becomes rough. Moreover, if the cooling mechanism is fully operated, the desired cooling temperature can be achieved, but it is difficult to improve the accuracy of temperature control near the product specification cooling temperature because of the temperature control by intermittent operation of the compressor. There was also a problem that the cooling specification of the company had to be increased.

  The present invention has been made in view of the above background, and an object of the present invention is to provide a centrifuge capable of shortening the cooling time lag while suppressing an increase in manufacturing cost by changing the evaporation temperature stepwise. There is.

  Another object of the present invention is to use a plurality of fixed throttle mechanisms and open / close valves to change the evaporation temperature in stages, to reduce temperature fluctuation (hunting) in the rotating chamber, and to achieve high temperature control accuracy. Is to provide.

  Still another object of the present invention is to use a cooling mechanism having the same compression function force to enable a high-speed rotor and a medium-to-low speed large rotor with large windage loss and a large capacity or high centrifugal acceleration to operate. Is to provide a machine.

  The characteristics of representative ones of the inventions disclosed in the present application will be described as follows.

According to one aspect of the present invention, a rotor for holding and centrifuging a sample, a motor that rotates the rotor, a chamber that defines a rotation chamber that houses the rotor, and a rotation chamber disposed on the outer periphery of the chamber. An evaporator for cooling the refrigerant, a compressor for circulating the refrigerant in the evaporator, a condenser for radiating the refrigerant compressed by the compressor, and an evaporator by adiabatically expanding the refrigerant that has been compressed and radiated In a centrifuge equipped with a throttle mechanism to be supplied to and a control unit for controlling these, a plurality of throttle mechanisms are provided in parallel, and an opening / closing valve operable by the control unit is provided in any or all of the plurality of throttle mechanisms, The control unit discriminates the type of the mounted rotor, and selects the throttle mechanism to be used using the on- off valve according to the type of the rotor . Throttle mechanism is a capillary tube, it may be provided each on-off valve of the plurality of capillary tubes, the rest of the capillary tube normally open providing only off valve to a part of the capillary tube of the plurality of capillary tubes It is good also as a state.

  According to another feature of the present invention, the controller controls the opening of the on-off valve to increase the amount of refrigerant supplied to the evaporator when it is necessary to increase the cooling speed of the rotating chamber. The controller controls the temperature of the rotating chamber by operating an on-off valve to the throttle mechanism during operation of the compressor.

  According to still another feature of the present invention, the control unit identifies the mounted rotor, and selects whether to control the on-off valve according to the type of the rotor and the centrifugal rotation speed. The control unit is provided with storage means for storing the type of rotor and the control information of the on-off valve in association with each other. The control information of the on / off valve is a rotation speed for controlling the opening / closing of the control valve.

According to the present invention, a centrifuge having a cooling mechanism is provided with a plurality of throttle mechanisms, provided with an on-off valve capable of operating a refrigerant supply to the throttling mechanism from a control unit, and is provided with a plurality of throttle mechanisms from the condenser using the on-off valve. The refrigerant supply to was controlled variably in stages. As a result, the evaporation temperature can be manipulated in stages, and the high-speed rotor that requires a temperature difference for cooling can be cooled by reducing the amount of refrigerant supplied to the evaporator by closing the on-off valve and lowering the evaporation temperature. it can. In addition, since the plurality of throttle mechanisms are provided with the on-off valves, respectively, the plurality of fixed throttle mechanisms can be individually controlled, and the evaporation temperature can be manipulated stepwise. Further, since the temperature control of the rotating chamber at the time of high windage loss can be controlled not by intermittent operation of the compressor but by switching the evaporation temperature, it is possible to perform highly accurate temperature control with little temperature change of the rotating chamber. In addition, since some of the plurality of throttle mechanisms are provided with on-off valves and the remaining throttle mechanisms are normally open, a plurality of evaporation temperatures can be set.

According to the present invention, the control unit opens the on-off valve when it is necessary to increase the cooling speed of the rotating chamber, and controls so that the amount of refrigerant supplied to the evaporator increases. However, when using a medium to low speed large rotor that does not require a temperature difference for cooling, it is possible to effectively cool by opening the on-off valve and increasing the amount of refrigerant supplied to the evaporator to increase the evaporation temperature. It becomes possible. In addition, the control unit controls the temperature of the rotating chamber by operating the on-off valve to the throttle mechanism during the operation of the compressor, so the centrifuge with high temperature control accuracy is reduced by reducing the hunting of the rotating chamber. Can be realized. Furthermore, the control unit identifies the mounted rotor and selects whether to control the on / off valve according to the rotor type and the centrifugal rotation speed. Control can be performed.

According to the present invention, the storage unit is provided in the control unit, and the type of rotor and the control information of the on-off valve are stored in correspondence with each other, so that the evaporation temperature can be efficiently operated according to the mounted rotor. As a result, it is possible to quickly cool the rotating chamber by opening the on-off valve at the beginning of operation when the rotating chamber needs to be cooled rapidly and increasing the amount of refrigerant supplied to the evaporator. Can be suppressed. Further, since the control information of the opening / closing valve is a rotation speed for controlling the opening / closing of the control valve, the control valve can be appropriately controlled to open / close according to the centrifugal rotation speed set by the user.

  The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

It is a schematic diagram which shows the structure of the centrifuge which concerns on the Example of this invention. It is a graph which shows the relationship between the evaporation temperature of a condensing unit, and a cooling capacity. It is a figure showing an example of operation | movement of each cooling mechanism of a centrifuge, and the temperature change of a cooling relevant part. It is a figure which shows an example of the temperature change of the cooling mechanism operation | movement in a prior art and temperature control by this invention, and a cooling relevant part. It is a data table which shows the correspondence of the rotor mounted | worn and capillary tube selection. It is a flowchart which shows the control procedure of the centrifuge which concerns on the Example of this invention. It is a schematic diagram which shows the structure of the centrifuge which concerns on the 2nd Example of this invention which has a some throttle mechanism and an on-off valve. It is a figure which shows an example of the data table which shows the corresponding | compatible relationship between the rotor with which the 2nd Example of this invention is mounted | worn, and capillary tube selection.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same portions are denoted by the same reference numerals, and repeated description is omitted. FIG. 1 is a schematic diagram showing the configuration of a centrifuge according to an embodiment of the present invention.

  The rotor 1 holds a container containing a sample, is mounted inside the chamber 4, and is rotated at a high speed by the drive unit 2. The rotating chamber 3 defined by the chamber 4 can be sealed by a door 14, and the evaporator 5 is disposed on the outer periphery of the chamber 4, whereby the inside of the rotating chamber 3 is cooled to a predetermined low temperature state. A temperature sensor 6 is provided at a predetermined location of the chamber 4, and the temperature of the rotor 1 is indirectly measured by measuring the air temperature inside the rotating chamber 3 by the temperature sensor 6. The cooling mechanism for cooling the rotating chamber 3 includes an evaporator 5, a compressor 7, a condenser 9, a fan 8, and capillary tubes (fixed throttle mechanisms) 10 </ b> A and 10 </ b> B. These include a return pipe 15 and a pipe. 16 to 18 are connected. Although the air-cooled condenser 9 is used in the cooling mechanism in the present embodiment, a water-cooled condenser can be used, and in that case, the fan 8 can be omitted.

  Between the piping 17 on the output side of the condenser 9 and the piping 18 on the evaporator 5 side, two capillary tubes 10A and 10B are connected in parallel. The capillary tubes 10A and 10B are components for introducing the liquefied high-pressure refrigerant compressed by the compressor 7 and cooled by the condenser 9 and the fan 8 into the evaporator 5 having a low pressure, and the capillary tubes 10A and 10B. The refrigerant flow rate is roughly determined by the inner diameter and the length. Here, if the capillary tubes 10A and 10B have small inner diameters, only a small amount of refrigerant flows, and the evaporation temperature in the evaporator 5 decreases. If the capillary tubes 10A and 10B have large inner diameters, a large amount of refrigerant flows. The evaporation temperature in the evaporator 5 becomes high.

  The capillary tubes 10A and 10B are made of, for example, copper tubes, and are configured with the same diameter and the same length. In the present embodiment, the opening / closing valve 11A is provided only in one capillary tube 10B, and the flow path to the capillary tube 10B can be opened or closed. In this embodiment, by closing the on-off valve 11A, the throttle channel becomes only the capillary tube 10A, and by opening the on-off valve 11A, the throttle channel becomes two tubes of the capillary tubes 10A and 10B. Thus, by operating one on-off valve, the flow of the refrigerant to the capillary tube 10B can be operated, and the number of capillary tubes to be used can be selected from one or two. Become.

  A temperature sensor 6 is provided in the rotating chamber 3 and the air temperature in the rotating chamber 3 is measured. A temperature sensor 19 is provided in the return pipe 15 from the evaporator 5 to the compressor 7, whereby the temperature of the refrigerant at the inlet of the compressor 7 is measured. Outputs of the temperature sensors 6 and 19 are transmitted to the control unit 12. The control unit 12 controls the entire centrifuge including the rotation control of the rotor 1, the operation and stop instructions of the compressor 7, the rotation of the fan 8, the opening and closing drive of the on-off valve 11A, and the like. And an electronic circuit including a storage device. The control unit 12 adjusts the cooling capacity of the evaporator 5 by controlling using the output of the temperature sensor 6. The cooling capacity of the evaporator 5 can be adjusted by using only the output of the temperature sensor 6 (in this case, the temperature sensor 19 can be omitted). Apart from this, it is also possible to adjust the cooling capacity of the evaporator 5 using the output of the temperature sensor 19. By using the output of the temperature sensor 19, the temperature of the refrigerant at the inlet of the compressor 7 is measured, the cooling state of the evaporator 5 at the time of rapid cooling when the on-off valve 11A is opened can be determined, the on-off valve 11A is closed, The timing for shifting to a lower evaporation temperature can be accurately measured.

In this embodiment, since the temperature of the rotating rotor 1 cannot be directly measured, the controller 12 indirectly determines the air temperature of the rotating chamber 3 measured by the temperature sensor 6, the type of the rotor 1, and the rotational speed. Next, the temperature of the rotor 1 is calculated.
Generally, the amount of heat Q transferred between media with a temperature difference is
Q = A · K · (T ₁ −T ₂ )
Where A is the heat transfer area, K is the heat transfer coefficient, T ₁ is the temperature of the object to be cooled, T ₂ is the temperature of the cooling body,
It becomes. When this is applied to the heat exchange of the rotor 1 of the centrifuge, the amount of heat Q transferred from the evaporator 5 to the rotor 1, that is, the air frictional heat value (windage loss) Q of the rotor 1 is
Q = A _r · K · (T _r −T _e )
Where _Ar is the surface area of the rotor 1, K is the overall heat transfer coefficient, _Tr is the rotor temperature, and _Te is the evaporator temperature.

In the centrifugal separator, in the rotational speed region where the windage loss is large and cooling is a problem, the air inside the rotating chamber 3 sufficiently reaches the turbulent flow, and the overall heat transfer coefficient K hardly changes. a surface area _{a r} of the rotor 1 temperature difference between the evaporator 5 and _(T r -T _e). From these equations, it can be seen that the rotor 1 having a larger surface area can be cooled with a smaller temperature difference (T _r −T _e ) between the rotor 1 and the evaporator 5 even with the same amount of windage loss. Since the temperature difference between the small rotor 1 surface area A _r which rotates at a high rotational speed and the rotor 1 required evaporator 5 (T r _{-T e)} increases conversely, it is necessary to lower the evaporation temperature T _e.

  On the other hand, the cooling capacity of the compressor 7 is limited by the size of the condenser 9, but the cooling capacity increases as the refrigerant evaporation temperature increases. An example of the relationship is shown in FIG. FIG. 2 shows the relationship between the evaporation temperature and the cooling capacity of a known condensing unit in which the compressor 7, the condenser 9 and the fan 8 are integrated. The solid line indicates the cooling capacity when the compressor suction temperature is 4.4 ° C., and the broken line indicates the cooling capacity due to the latent heat of vaporization of the refrigerant when the compressor suction temperature is 4.4 ° C. When the evaporation temperature is increased from −30 ° C. to −27 ° C., the cooling capacity is increased from 355 W to 419 W and increased by 64 W, and the cooling capacity is improved by about 18%. At this time, the latent heat of vaporization that actually contributes to cooling increases by 55 W from 272 W to 327 W and increases by 20%. The present invention pays attention to such a load form peculiar to the centrifuge and general characteristics of the compressor, and is configured to switch the evaporation temperature step by step by selecting the number of capillary tubes to be used. The mechanism is realized at low cost.

  As shown in FIG. 1, in this embodiment, two capillary tubes 10A and 10B are provided in the cooling mechanism, and the capillary tube 10A can be controlled to flow or stop the refrigerant by opening and closing the on-off valve 11A. Is always in a conducting state without an on-off valve. In order to achieve the object of the present invention, an on-off valve may be provided on the capillary tube 10B side. However, since this increases the manufacturing cost, the present embodiment is configured with a small number of on-off valves.

  A user of the centrifuge stores a sample in the rotor 1 and sets the rotor 1 at the tip of the rotation shaft of the drive unit 2 in the rotation chamber 3. Next, operation information such as the type, rotation speed, and temperature setting of the rotor 1 is input to the control unit 12 via an input unit such as an operation panel (not shown). Based on this operation information, the magnitude of the windage loss of the mounted rotor 1 and whether it is a large rotor rotating at medium or low speed or a small rotor rotating at high speed are determined, and the on-off valve 11A is opened / closed. When the mounted rotor 1 is a high-speed rotor in which the temperature difference between the rotor 1 and the evaporator 5 is prioritized over the cooling capacity, the on-off valve 11A is controlled to be closed, and the refrigerant flow rate flowing to the evaporator 5 is reduced. The evaporation temperature of the evaporator 5 is lowered, and the temperature difference between the rotor 1 and the evaporator 5 is increased.

  On the other hand, when the mounted rotor 1 is a medium- and low-speed large rotor that gives priority to the cooling capacity over the temperature difference between the rotor 1 and the evaporator 5, the on-off valve 11A is opened to increase the refrigerant flow rate. Increase the evaporation temperature and increase the cooling capacity. The centrifugal separator provided with the cooling mechanism according to the present invention can change the evaporation temperature stepwise but can be made variable, and the same high-speed rotor as the conventional one with the same capacity of the compressor 7 as the conventional cooling mechanism. As a result, it is possible to make it possible to operate a medium-to-low speed large rotor having a larger capacity or higher centrifugal acceleration than in the past.

FIG. 3 is a graph showing an example of the operation of each cooling mechanism of the centrifuge and the temperature change of the cooling-related part. The horizontal axis of each graph is the elapsed time, and the graphs (1) to (6) are displayed on the same scale. FIG. 3 (1) shows the rotational speed 31 of the rotor 1. The rotation speed 31 can be detected by detecting the rotation speed of the motor included in the drive unit 2. Rotational speed 31 is centrifuged operation is started to rise by the acceleration of the rotor 1 is rotated at a constant rotational speed after reaching the rotational speed N _A that has been set.

Control unit 12 identifies the loaded type rotor 1, the rotational speed of the rotor 1 which is set by the user, depending on the current temperature of the rotating chamber 3, rotating the rotor 1 at the set rotational speed N _A In such a case, the number of times the air temperature inside the rotating chamber 3 should be calculated is calculated, and the cooling mechanism is controlled. If the set temperature is low, the controller 12 operates the compressor 7 and the fan 8 almost simultaneously with the start, and starts rapid cooling of the rotating chamber 3. FIG. 3B shows the rotor temperature 32 at that time. The curve indicated by the solid line is the rotor temperature 32 in this embodiment. Approaches the rotational speed N _A of the rotor 1 is set to start rotating, the temperature of the rotor 1 due to the influence of windage loss slightly increases, while the rotation by the cooling operation of the cooling mechanism into operation chamber 3 Since the inside is cooled, the temperature rise of the rotor 1 is prevented, and the temperature remains almost at the original temperature. The curve indicated by the dotted line in FIG. 3B is the rotor temperature 42 in the conventional centrifuge, and the rotor temperature 32 is much smaller than the rotor temperature 42 in the temperature rise portion after the rotor 1 is settled. You will understand that

  The curve shown in FIG. 3 (3) is an air temperature 33 indicating the internal temperature (air temperature) of the rotating chamber 3. The centrifuge of this example is configured so that the flow of the refrigerant can be controlled using the two capillary tubes 10A and 10B. Therefore, in the case of high-speed operation of a high-speed rotor in which the evaporation temperature is more important than the cooling capacity, the on-off valve 11A is operated for a predetermined time from the start of operation or until the measured value of the temperature sensor 6 (or 19) falls below the predetermined temperature. Open and control to increase the flow rate of the refrigerant. As a result, it is possible to reduce the time required for the air temperature in the rotating chamber 3 to drop to the control temperature immediately after the rotation of the rotor 1 starts, and to suppress the temperature rise of the rotor 1 during that period. An air temperature 43 indicated by a dotted line in FIG. 3 (3) indicates the internal temperature (air temperature) of the rotating chamber 3 according to the prior art. According to the present embodiment, it is possible to control the flow rate of the refrigerant to be increased by opening the on-off valve 11A and using the two capillary tubes 10A and 10B, so that the temperature of the rotating chamber 3 can be rapidly reduced. Become.

  FIG. 3 (4) shows an inlet temperature curve and an outlet temperature curve of the evaporator 5, which are indicated by a solid line as an inlet temperature curve 34 and an outlet temperature curve 35 according to this embodiment, and indicated by a dotted line according to the prior art. An inlet temperature curve 44 and an outlet temperature curve 45 are shown. In the case of this embodiment, in order to increase the temperature of the rotor and the evaporator, the cooling capacity of only the latent heat of evaporation is used. Therefore, after a certain period of time has elapsed after operation, the evaporator 5 The inlet temperature and outlet temperature are almost the same. Immediately after the operation of the cooling mechanism, the outlet temperature becomes higher and the inlet temperature becomes lower. However, in the present embodiment, the inlet temperature curve 34 and the outlet temperature curve 35 converge to substantially the same temperature at an early stage, so that the cooling mechanism can be stably operated at an early stage. In the cooling mechanism shown in the related art, the inlet temperature curve 44 becomes lower immediately after the start, the outlet temperature curve 45 becomes higher, and the temperature difference between the two is large. In addition, the temperatures of both are substantially the same as the convergence points of the inlet temperature curve 34 and the outlet temperature curve 35.

  FIG. 3 (5) is a graph showing the open / close state 36 of the open / close valve 11A. In the conventional cooling mechanism, only the capillary tube 10 </ b> B is controlled, which is equivalent to the control indicated by the open / close valve 11 </ b> A being closed, that is, the open / closed state 46. In this embodiment, the on-off valve 11A is opened until the temperature difference between the inlet temperature curve 34 and the outlet temperature curve 35 is sufficiently small, and the on-off valve is closed after the temperature difference is sufficiently small. The opening / closing operation of the opening / closing valve 11A is performed inside. FIG. 3 (6) is a graph showing the operating state 37 of the compressor 7. In this embodiment, the compressor 7 is not intermittently driven, but is continuously driven to adjust the cooling capacity using the on-off valve 11A. I tried to do it.

  Next, the operation of the cooling mechanism while the rotor 1 is set will be described with reference to FIG. FIG. 4 shows the operation of the cooling mechanism and the temperature change of the cooling-related part in the temperature control according to this embodiment. The graph shown by the solid line is the control of this embodiment, and the curve shown by the dotted line is the control in the conventional example. Shows that. From the rotor type, rotation speed, and temperature set by the user, the centrifugal separator is judged to have a larger air temperature hunting width in the rotating chamber 3 in the conventional intermittent compressor operation (using one capillary tube). In this case, the temperature control method using the second capillary tube is switched. For this reason, the control part 12 calculates the control temperature of the air temperature of the rotation chamber 3 according to the operating conditions set by the user. When the air temperature in the rotating chamber 3 becomes lower than the calculated control temperature due to the operation of the compressor 7, the on-off valve 11A is opened, the pressure in the evaporator 5 is increased, the evaporation temperature of the refrigerant is increased, and the rotating chamber 3 is increased. Increase the air temperature. If the on-off valve 11A is closed after the air temperature in the rotating chamber 3 rises to a predetermined temperature, the temperature of the rotating chamber decreases, so that the temperature can be controlled only by opening and closing the solenoid valve. The portion indicated by the dotted line shows the operation of the cooling mechanism in the temperature control by the intermittent compressor operation of the prior art and the temperature change of the cooling related part.

  In the present embodiment, unlike the conventional control method in which the compressor 7 is intermittently driven as indicated by 64 in FIG. 4 (4), the control is performed while the compressor 7 is continuously driven as indicated by 54. On the other hand, as shown by 53 in FIG. 4 (3), the cooling capacity is controlled by opening and closing the on-off valve 11A as necessary. Therefore, as shown in FIG. 4A, the temperature of the rotor 1 has a smaller amplitude and a shorter period of the temperature curve 51 of the present embodiment than the conventional temperature curve 61. Therefore, the fluctuation range of the temperature of the rotor 1 can be reduced. FIG. 4 (2) shows the temperature of the rotating chamber 3, and when the temperature of the rotating chamber decreases, the on-off valve 11A is opened, and when the temperature of the rotating chamber 3 increases, the on-off valve 11A is closed. Compared with the conventional temperature curve 62, the temperature curve 52 of the present embodiment is significantly smaller.

  FIG. 5 is a data table showing the correspondence between the rotor to be mounted and the capillary tube selection. Normally, in the centrifuge, the type of the rotor 1 mounted in the rotating chamber 3 is identified by the control unit 12, and the rotor name 71, the rotor ID 72, the maximum allowable rotational speed 73 of the rotor, the rotational radius 74, Various control information such as the balance detection level 75 is stored in the control unit 12 in advance. The contents shown in FIG. 5 are recorded in a data table format in a storage device (not shown) included in the control unit 12. In this embodiment, a capillary selection rotation speed 76 is added to this data table. The capillary selection rotation speed 76 means that when the rotation speed for centrifugation set by the user is higher than the capillary selection rotation speed 76, the opening / closing valve 11A is controlled to open. When the rotation speed is lower than the capillary selection rotation speed 76, the on-off valve 11A is not opened, so that only the capillary tube 10B side is used without using the passage on the capillary tube 10A side.

  As described above, in the control in the present embodiment, the type of the mounted rotor 1 is identified, and the cooling mechanism is controlled using the capillary selective rotation speed 76 that is different for each identified rotor. By controlling in this way, accurate cooling control can be performed using a simple cooling mechanism using the capillary tubes 10A and 10B and the on-off valve 11A.

  Next, the control procedure of the centrifuge according to the embodiment of the present invention will be described using the flowchart of FIG. The control procedure shown in FIG. 6 is realized by software by executing a program by a microcomputer included in the control unit 12. First, the user selects a sample container to be centrifuged and a rotor 1 suitable for the rotation speed of the centrifuge, puts it in the rotation chamber 3, and inputs operation setting information for centrifuge from an operation panel (not shown). (Step 81). Here, the information input from the operation panel includes a set rotation speed at the time of centrifugal separation, a set temperature of the rotor 1, an operating time of the rotor 1, a rotor No. and the like.

  When the necessary information is input, the controller 12 determines whether the set rotational speed is appropriate, that is, the set rotational speed is determined by the maximum rotational speed 73 stored in the data table of FIG. It is determined whether the speed is below (step 82). If the rotation speed set by the user is greater than the maximum rotation speed 73 stored in the data table, an alarm indicating that a setting error has occurred is displayed (step 83), and the process returns to step 81. When the set rotational speed is equal to or lower than the maximum rotational speed 73 stored in the data table, the process waits for the user to input the centrifugal start switch, and when it is input, the drive unit 2 is started to activate the rotor 1. Is started (step 84).

  Next, immediately after the rotation of the rotor 1 starts, the rotor ID is detected by identifying the identifier displayed on the rotor 1, and it is determined whether the correspondence between the rotor name input by the user and the rotor ID 72 is correct. (Step 85). Various identification methods for identifying the rotor 1 have been proposed so far. For example, an adapter in which four magnets having different arrangement angles according to the type of the rotor are mounted on equidistant lattice points on the same circumference around the rotation axis of the rotor 1 is attached. A magnetic sensor that detects the arrangement angle of the magnet is arranged at predetermined intervals in the rotation chamber, and the magnet position is calculated by performing a predetermined calculation on the detection intensity detected by the adjacent magnetic sensor to detect the type of rotor. Can be specified. If the correspondence is not correct in step 86, the control unit 12 uses the data table of FIG. 5 to determine whether the set rotational speed is lower than the maximum rotational speed 73 corresponding to the rotor ID 72 detected by the identifier. Determine whether. If it is lower than the maximum rotation speed 73, the rotor ID can be changed as it is, so that the centrifugal operation can be performed. Therefore, the display of the rotor name is changed and the routine proceeds to step 89 (step 88). If the rotational speed is lower than the maximum rotational speed 73, the centrifugal separation operation cannot be continued, so an alarm is displayed and the rotor 1 is decelerated and the process returns to step 81 (step 87).

  In step 85, if the correspondence between the rotor name input by the user and the rotor ID 72 is correct, the value of the capillary selection rotational speed 76 corresponding to the detected rotor ID is obtained by referring to the data table shown in FIG. Then, it is determined whether or not the rotation speed set by the user is higher than the obtained capillary selection rotation speed 76 (step 89). When the set rotational speed is higher than the capillary selected rotational speed 76, the control with opening / closing of the on-off valve 11A is selected (step 90), and when the set rotational speed is lower than the capillary selected rotational speed 76, the on-off valve 11A is turned on. Control is selected that is always closed, that is, only the capillary tube 10B is used without using the capillary tube 10A (step 91).

  Next, using the control mode selected in step 90 or 91, the centrifugal operation for the set time is performed (step 92). If the control using the on-off valve 11A is selected in step 90, the cooling mechanism is controlled based on the control method described in FIGS. Further, when the control not using the on-off valve 11A is selected in Step 90 (the on-off valve is always closed), the cooling mechanism is controlled using a known control method using only the capillary tube 10B.

  Next, it is determined whether the centrifugal separation operation has been performed for the set time (step 93). If the set time has not elapsed, the process returns to step 92. When the set time has elapsed, the rotation of the rotor 1 is stopped by controlling the drive unit 2 to stop, the cooling mechanism is stopped by stopping the compressor 7, and the centrifugal separation operation is ended. (Step 94).

  As described above, according to the present embodiment, it is possible to operate the evaporation temperature stepwise by providing the operable refrigerant flow opening / closing valve and a plurality of fixed throttle mechanisms (capillary tubes). Thus, control equivalent to that of the variable aperture mechanism can be realized without cost. In addition, since the stepwise operation of the evaporation temperature is controlled according to the rotor 1 to be mounted and the set rotational speed for the centrifugal separation, the cooling mechanism can be controlled with high accuracy. In this embodiment, two capillary tubes are used and one on-off valve is used. However, the present invention is not limited to this, and m capillary tubes and n on-off valves (however, 0 <n ≦ m) are used. Anyway. In this embodiment, the capillary tube is used as the fixed throttle mechanism, but other throttle mechanisms may be used.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a schematic diagram showing the configuration of a centrifuge according to a second embodiment having a plurality of throttle mechanisms and on-off valves. In FIG. 7, the same parts as those in FIG. The centrifuge of FIG. 7 differs from the first embodiment in that three capillary tubes 110A, 110B, and 110C are used, and opening and closing operations that open and close the refrigerant flow to the capillary tubes 110A, 110B, and 110C. The valves 111A, 111B, and 111C are provided respectively. The flow path diameters and lengths of the capillary tubes 110A, 110B, and 110 may be the same or may be set to be different. In the case of this cooling mechanism, a maximum of six evaporating temperatures can be selected depending on the combination of whether or not a capillary tube is used and whether or not the on-off valve 111 (111A, 111B, 111C) is open / closed. The control of the on-off valve 111 is controlled by the control unit 12 using the data table shown in FIG.

  FIG. 8 is a data table showing the correspondence between the rotor to be mounted and the capillary tube selection. This data table is stored in advance in a storage device (not shown) in the control unit 12, and as information about the rotor 1, as in the data table shown in the first embodiment, the rotor name 101, the rotor ID 102, and the permission of the rotor. Various control information such as the maximum rotation speed 103 and the rotation radius 104 are stored. In the second embodiment, three pieces of capillary selection information 105 to 107 that can be controlled by the on-off valve 111 are further stored. Each capillary selection information 105 to 107 stores a rotation speed range and an open / close state of the open / close valve 111 (111A, 111B, 111C). These open / close states are finely defined in three stages according to the rotational speed of the rotor 1.

For example, when the mounted rotor 1 is “R10A”, the rotational speed for centrifugation set by the user is ⁰ to 5,000 min ⁻¹ , 5,001 to 8,000 min ⁻¹ , 8, The difference is in the range of 001 to 10,010 min ⁻¹ . For example, when the set rotational speed is 7,000 min ⁻¹ , it falls within the range of the capillary selection information 106, and thus is controlled with the on-off valve 111 (111A, 111B, 111C) = (open, open, closed). It will be. That is, the on-off valves 111A and 111b are controlled to open and close, but the on-off valve 111C is always closed.

  According to the second embodiment, by using three sets of capillary tubes and on-off valves, the evaporation temperature can be controlled in multiple stages in accordance with the mounted rotor, and the initial stage of operation in which the rotating chamber needs to be rapidly cooled. It is possible to quickly cool the rotating chamber by opening the on-off valve and increasing the amount of refrigerant supplied to the evaporator. In addition, since such multi-stage control can be realized with a simple structure and an inexpensive capillary tube and on-off valve, it is possible to realize a centrifugal separator that suppresses an increase in manufacturing cost.

  According to the second embodiment, since the plurality of throttle mechanisms are provided with the on-off valves, respectively, the plurality of fixed throttle mechanisms can be individually controlled, and the evaporation temperature can be manipulated stepwise. As a result, highly accurate temperature control with little temperature change of the rotating chamber is possible.

  As mentioned above, although this invention was demonstrated based on the Example, this invention is not limited to the above-mentioned Example, A various change is possible within the range which does not deviate from the meaning. For example, in FIG. 1, no opening / closing valve is provided on the capillary tube 10B side, but an opening / closing valve may be provided similarly on the capillary tube 10B side. Further, in the case of a cooling mechanism having a plurality of throttle mechanisms and on-off valves such as the centrifuge shown in FIG. 7, control may be performed so that any plurality of on-off valves are operated asynchronously.

DESCRIPTION OF SYMBOLS 1 Rotor 2 Drive part 3 Rotating chamber 4 Chamber 5 Evaporator 6 Temperature sensor 7 Compressor 8 Fan 9 Condenser 10A, 10B Capillary tube 11A On-off valve 12 Control part 14 Door 15 Return piping 16, 17, 18 Piping 19 Temperature sensor 31 , 41 Rotational speed 32, 42 Rotor temperature 33, 43 Air temperature 34, 44 Inlet temperature curve 35, 45 Outlet temperature curve 36, 46 Open / closed state 37 Operating situation 51, 61 Temperature curve 52, 62 Temperature curve 71 Rotor name 72 Rotor ID
73 Maximum rotation speed 74 Turning radius 75 Imbalance detection level 76 Capillary selection rotation speed 82 Setting rotation speed 101 Rotor name 102 Rotor ID
103 Maximum rotation speed 104 Turning radius 105 to 107 Capillary selection information 110A, 110B, 110C Capillary tube 111 (111A, 111B, 111C) On-off valve

Claims (6)

A rotor for holding and centrifuging a sample, a motor for rotating the rotor, a chamber for defining a rotation chamber for housing the rotor, and an evaporation for cooling the rotation chamber disposed on the outer periphery of the chamber A compressor for circulating the refrigerant in the evaporator, a condenser for radiating the refrigerant compressed by the compressor, and adiabatic expansion of the compressed and radiated refrigerant is supplied to the evaporator In a centrifuge equipped with a throttle mechanism and a controller for controlling these,
A plurality of the throttling mechanisms from the condenser to the evaporator are provided in parallel ,
An opening / closing valve operable from the control unit is provided in any or all of the plurality of throttle mechanisms,
The control unit determines the type of the mounted rotor,
The centrifuge is characterized in that the throttling mechanism to be used is selected using the on-off valve according to the type of the rotor . The throttling mechanism is a capillary tube,
Off valve provided in a part of the plurality of capillary tubes,
The centrifuge according to claim 1, wherein the remaining capillary tubes are normally opened. Wherein the control unit according to claim 1 or 2, characterized in that selected or closed to open each of the on-off valve in accordance with the centrifuge rotational speed set the type of the previous SL rotor mounted Centrifuge. A storage unit is provided in the control unit, and control information indicating which open / close valve to open in the throttle mechanism is tabulated according to the type of the rotor and the centrifugal rotation speed, and stored in the storage unit in advance. The centrifuge according to claim 3 . 2. The control unit according to claim 1 , wherein when the cooling of the rotating chamber needs to be accelerated, the control unit opens the on-off valve to control the amount of refrigerant supplied to the evaporator. The centrifuge according to any one of 4 . 6. The control unit according to claim 1 , wherein the controller performs temperature control of the rotating chamber without stopping the compressor by operating an on-off valve of the throttle mechanism during operation of the compressor . The centrifuge according to any one of the above.

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