JP2011230085A - Centrifugal separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely control an oil diffusion vacuum pump in a centrifugal separator which makes the inside of a rotation chamber in a high vacuum state by using the oil diffusion vacuum pump.SOLUTION: The centrifugal separator 1 includes: a rotor 2 which is rotated by a driving device 8 and retains a sample; the rotation chamber 3 which houses the rotor 2; and the oil diffusion vacuum pump 5 and an oil rotation vacuum pump 4 which decrease pressure the inside of the rotation chamber 3 to prescribed vacuum; wherein a first and a second temperature sensors 10, 11 are disposed on two sites which are located in a cooling part of diffusion oil of the oil diffusion vacuum pump 5 and generate a temperature difference therebetween, and the electricity conduction to a heater 54 of the oil diffusion vacuum pump 5 is controlled by using the temperature difference detected by the temperature sensors 10, 11. The temperature sensors 10, 11 are disposed on the two sites separated in the vertical direction of the outer wall of a tubular cooling part 56, and the drive of the heater 54 is feed-back controlled by using the detected temperature difference.

Description

  The present invention relates to an apparatus for reducing the pressure in a rotating chamber to a high vacuum by an oil diffusion vacuum pump in order to prevent temperature rise due to windage loss of the rotor, such as a centrifuge that rotates a rotor at high speed.

  A centrifuge separates and refines a sample by inserting a sample to be separated into a rotor through a tube or a bottle and rotating the rotor at a high speed. The rotational speed varies depending on the application, and ranges from low speed (the maximum rotational speed is several thousand revolutions per minute) to high speed (the maximum rotational speed is about 150,000 revolutions per minute). Among them, a centrifuge with a rotational speed of about 40,000 revolutions or more per minute called an ultracentrifuge needs to keep the temperature of the sample low when separating a sample such as an enzyme or protein. The rotating chamber is controlled at a constant temperature by a cooling device so that the temperature of the sample does not rise. Furthermore, in the ultracentrifuge, since the rotor is rotated at a high speed, the rotary chamber can be decompressed to a high vacuum by a vacuum pump so that the temperature of the rotor does not rise due to frictional heat with air. Conventionally, an oil diffusion vacuum pump has been widely used as a vacuum pump for reducing the pressure of a rotating chamber to a high vacuum state.

  As a method of controlling the oil diffusion vacuum pump of the centrifuge, a method of measuring the room temperature in the centrifuge (the temperature inside the housing) and turning on / off the heater is known. If the heater of the oil diffusion vacuum pump is driven by always energizing for a certain time only at the start of control, there is a risk of malfunction. For example, if the heater temperature is high at the start of control, the boiler will be overheated, and the oil molecules that have vaporized will not be liquefied in the cooling section and will flow back into the rotating chamber, leading to a deterioration in the degree of vacuum or the body itself being hot. Therefore, there is a risk of deteriorating non-metallic parts such as an O-ring and a vacuum hose at the connection portion. In order to prevent such problems, various methods of energizing the heater (driving method) have been devised. However, in the technique of Patent Document 1, in addition to room temperature, the temperature of the oil diffusion vacuum pump is measured by a temperature sensor. It was proposed to control the heater of the vacuum pump. In this technique, the target temperature of the oil diffusion vacuum pump is set based on the room temperature, and the control device controls the energization of the heater so that the target temperature is reached.

  Here, a conventional centrifugal separator 101 disclosed in Patent Document 1 will be described with reference to FIG. The centrifuge 101 includes a rotor 102 for containing a sample, a driving device 108 for rotating the rotor 102, a rotating chamber 103 for inserting the rotor 102, and two vacuum pumps (oil rotating vacuum for reducing the pressure inside the rotating chamber 103 to a high vacuum. The pump 104, the oil diffusion vacuum pump 105), the vacuum pipe 107 connecting the rotary chamber 103 and the oil diffusion vacuum pump 105, and the vacuum pipe 106 connecting the oil diffusion vacuum pump 105 and the oil rotary vacuum pump 104 are arranged, and the driving device 108 And a control device 109 for controlling the oil diffusion vacuum pump 105, the oil rotary vacuum pump 104, and the like, an operation unit 113 for operating the control device 109, and the like. In order to control the oil diffusion vacuum pump 105, a temperature sensor 114 for measuring room temperature (temperature in the casing) is provided in the casing of the centrifuge 101, and the degree of vacuum inside the rotating chamber 103 is measured. A vacuum gauge 112 is provided. In addition, a part of the cooling fin of the oil diffusion vacuum pump 105 is provided with one temperature sensor 110 that measures the temperature. The oil rotary vacuum pump 104 serves as an auxiliary vacuum pump for causing the oil diffusion vacuum pump 105 to function, and is provided on the downstream side of the oil diffusion vacuum pump 105 via the vacuum pipe 106.

Japanese Patent No. 3870626

  In recent years, there has been a growing need for shortening the time from when the centrifuge is turned on until the start of the centrifuge in an ultrahigh speed centrifuge. In order to meet these needs, it is important to set the pressure in the rotating chamber to a high vacuum state in a short time. For this reason, the heater of the oil diffusion vacuum pump used to make the rotating chamber high vacuum is high. A power heater or a cartridge heater with good heating efficiency is used to reach the oil temperature at which the performance of the oil diffusion vacuum pump can be demonstrated in a short time. Furthermore, when the temperature of the oil reaches the level at which the performance of the oil diffusion vacuum pump can be exhibited, the heater is controlled with high accuracy by PID feedback control and pulse width control so that the oil does not rise to an unnecessarily high temperature. . In particular, when the heater 154 is heated at 100% power so that the oil reaches the target temperature in a short time, when the temperature approaches the target temperature, for example, the PID starts when the temperature is 5% or 5 ° C. lower than the target temperature. By switching to feedback control or pulse width control, the oil temperature is controlled not to rise more than necessary.

  However, when the temperature of the oil is in the vicinity of the target temperature, the control conditions vary if the room temperature of the centrifuge serving as a reference for temperature management varies. For example, when the room temperature decreases, the target temperature generally decreases, and depending on the temperature, overheating occurs immediately. When overheating occurs, heating by the heater 154 is stopped until the target temperature returns to the allowable range. However, since the capability of the oil diffusion vacuum pump 105 is reduced by stopping the heating, the pressure in the rotating chamber increases. Depending on the degree of the pressure increase, a pressure error may occur and the centrifugal separation that has started must be stopped. Therefore, control that does not cause these problems is important.

  The present invention has been made in view of the above background, and an object thereof is to accurately control an oil diffusion vacuum pump in a centrifuge that uses an oil diffusion vacuum pump to make a high vacuum in a rotating chamber. is there.

  Another object of the present invention is to provide a centrifuge capable of stably controlling an oil diffusion vacuum pump without changing the target temperature even if the ambient temperature of the centrifuge varies.

  Still another object of the present invention is to prevent a sudden pressure increase in the rotating chamber due to the stop of heating of the oil of the oil diffusion vacuum pump during the process from the sudden temperature rise of the oil of the oil diffusion vacuum pump to the temperature stabilization. It is to provide a centrifuge capable of being controlled.

  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 centrifugal separator having a driving device, a rotor that is rotated by the driving device to hold a sample, a rotating chamber that houses the rotor, and an oil diffusion vacuum pump that depressurizes the rotating chamber to a predetermined vacuum. In the separator, the first and second temperature sensors are provided at two locations where the temperature difference occurs in the cooling unit for the diffusion oil of the oil diffusion vacuum pump, and the temperature difference detected by the first and second temperature sensors is used. The power supply to the heater of the oil diffusion vacuum pump was controlled. An oil rotary vacuum pump is connected in series as an auxiliary pump to the oil diffusion vacuum pump, and the rotor is controlled to be accelerated to a set number of rotations when the rotation chamber reaches the first vacuum degree. The first and second temperature sensors are preferably provided at two locations separated in the vertical direction of the outer wall of the cylindrical cooling section.

    According to another feature of the present invention, a plurality of cooling fins extending in the radial direction are provided at a substantially central portion in the vertical direction of the cooling unit, and the first temperature sensor is provided on the outer wall of the cooling unit below the cooling fins. The second temperature sensor is configured to be provided on the outer wall of the cooling unit above the cooling fin. As another installation position of the temperature sensor, the first temperature sensor may be provided on the lower cooling fin, and the second temperature sensor may be provided on the upper cooling fin.

  According to still another aspect of the present invention, the heater is fully energized until the temperature difference detected by the first and second temperature sensors reaches a predetermined value after the oil diffusion vacuum pump is started, and the detected temperature When the difference reaches a predetermined value, control is performed so as to keep the detected temperature difference at the predetermined value by adjusting energization to the heater. The control for maintaining the predetermined value can be performed by feedback control of energization to the heater. If the temperature difference detected by the first and second temperature sensors does not reach a predetermined temperature difference even after a certain time has elapsed after the start of energization of the heater, there is a possibility that some abnormality has occurred. Stop energizing.

  According to the first aspect of the present invention, the temperature sensor is provided in the low-temperature part and the high-temperature part of the cooling part of the oil diffusion vacuum pump, and the heater is controlled using the temperature difference, thereby relating to the ambient temperature of the centrifuge. This makes it possible to control the temperature of the oil diffusion vacuum pump. Further, a stable centrifugal operation can be performed without being affected by the temperature change of the installation environment temperature of the centrifuge.

  According to the second aspect of the present invention, the first and second temperature sensors are provided at two locations separated from each other in the vertical direction of the outer wall of the cylindrical cooling unit, so that one temperature sensor is provided on the outer wall from the conventional structure. Only by adding, it becomes possible to control the temperature of the oil diffusion vacuum pump regardless of the ambient temperature of the centrifuge.

  According to the invention of claim 3, a plurality of cooling fins extending in the radial direction are provided at a substantially central portion in the vertical direction of the cooling section, and the first temperature sensor is provided on the cooling section outer wall below the cooling fin. Since the second temperature sensor is provided on the outer wall of the cooling unit above the cooling fin, the temperature of the part before and after the cooling action by the cooling fin can be detected effectively. A sufficient temperature difference can be obtained from the temperature sensor, and accurate temperature management can be performed.

  According to the invention of claim 4, a plurality of cooling fins extending in the radial direction are provided at a substantially central portion in the vertical direction of the cooling portion, the first temperature sensor is provided on the lower cooling fin, and the second Since the temperature sensor is provided on the upper cooling fin, the present invention can be realized even when it is difficult to attach the temperature sensor to the outer wall of the cylindrical cooling part.

  According to the invention of claim 5, since the heater is energized with full power until the temperature difference detected by the first and second temperature sensors reaches a predetermined value after the oil diffusion vacuum pump is started, the shortest time is required. The diffusion oil of the oil diffusion vacuum pump can be efficiently heated, and the rotation chamber can be decompressed to a high vacuum state in a short time.

  According to the sixth aspect of the present invention, since the energization to the heater is feedback controlled so that the detected temperature difference is maintained at a predetermined value, the target temperature does not vary even if the ambient temperature of the centrifuge varies, It is possible to realize the control that does not cause the heating stop and the pressure increase in the rotating chamber due to this.

  According to the seventh aspect of the present invention, when the detected temperature difference does not reach the predetermined temperature difference even after a certain time has elapsed after the start of energization to the heater, the energization to the heater is stopped. When the required amount of diffusion oil does not exist, problems due to deterioration of diffusion oil can be detected early.

  According to the eighth aspect of the present invention, the oil rotary vacuum pump is provided in series with the oil diffusion vacuum pump, and when the rotation chamber reaches the first vacuum degree, the rotor is accelerated to the set number of rotations. It is possible to efficiently depressurize the rotating chamber.

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

It is a figure which shows the whole structure of the centrifuge 1 which concerns on the Example of this invention. It is a whole block diagram which shows the oil diffusion vacuum pump 5 of FIG. 1, The left half is shown with the side view, and the right half is shown with the fragmentary sectional view. It is a graph which shows the relationship between elapsed time and the pressure in the rotation chamber 3 at the time of operating the oil diffusion vacuum pump 5 and the oil rotary vacuum pump 4. FIG. It is a graph which shows the relationship between the detection temperature by the temperature sensors 10 and 11 at the time of operating the oil diffusion vacuum pump 5, and elapsed time. It is a figure which shows the relationship between the temperature difference ((DELTA) t) of the temperature sensors 10 and 11, and elapsed time (min). It is the characteristic view which showed the example of a measurement of the temperature sensor detection temperature difference and rotation chamber pressure of the centrifuge shown in FIG. It is a flowchart which shows operation | movement of the centrifuge 1 which concerns on the Example of this invention. It is a figure which shows the whole structure of the centrifuge 101 which concerns on a prior art.

  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 diagram showing the overall configuration of a centrifuge 1 according to the present invention. The centrifuge 1 includes a rotor 2 for putting a sample, a driving device 8 that rotates the rotor 2, a rotating chamber 3 that houses the rotor 2, an oil diffusion vacuum pump 5 that depressurizes the rotating chamber 3 to a high vacuum, An oil rotary vacuum pump 4 acting as an auxiliary vacuum pump for causing the oil diffusion vacuum pump 5 to function, a vacuum pipe 7 connecting the rotary chamber 3 and the oil diffusion vacuum pump 5, an oil diffusion vacuum pump 5 and an oil rotation vacuum pump 4 And a vacuum pipe 6 connecting the two. The drive device 8, the oil diffusion vacuum pump 5, and the oil rotary vacuum pump 4 are controlled by the control device 9, and an operation unit 13 is provided for operating the control device 9. Further, the control device 9 is provided with a temperature sensor 14 for measuring the room temperature of the centrifuge 1. The rotating chamber 3 is sealed by an openable / closable door (not shown) and decompressed in that state. A vacuum gauge 12 for measuring the pressure in the rotating chamber 3 is provided on the side surface of the rotating chamber 3, and its output is input to the control device 9.

  Since the oil diffusion vacuum pump 5 cannot be evacuated from the atmospheric pressure, the oil rotary vacuum pump 4 is first evacuated to a certain degree of vacuum, and then the oil diffusion vacuum pump 5 is operated to reach a predetermined degree of vacuum. The rotary chamber 3 is depressurized using two vacuum pumps until it reaches. The oil diffusion vacuum pump 5 includes a boiler for storing oil, a heater for heating the boiler, a jet for injecting oil molecules vaporized in the boiler in a certain direction, and a cooling cylinder for cooling and liquefying the vaporized oil molecules. It consists of. A temperature sensor (first temperature sensor) 10 is provided on the high temperature side (side near the heater 54) of the cooling cylinder 56 of the oil diffusion vacuum pump 5, and a temperature sensor (second temperature sensor) is provided on the low temperature side (side far from the heater 54). ) 11.

  Next, the principle of the oil diffusion vacuum pump 5 will be described with reference to FIG. FIG. 2 is an overall configuration diagram showing the oil diffusion vacuum pump 5 of FIG. 1, showing the left half as a side view and the right half as a partial cross-sectional view. The oil diffusion vacuum pump 5 includes a boiler 51 for generating oil vapor, chimney portions 52a and 52b extending upward from the boiler, nozzles 55a and 55b provided above the chimney portions 52a and 52b, and jetting oil vapor, A cooling cylinder 56 that condenses the injected steam is included. The boiler 51 is provided with a heater 54 for heating the diffusion oil 53 so as to extend inside the center, and on / off of the heater 54 is controlled by the control device 9. Although any heater can be used as the heater 54, for example, an aluminum cast heater or a cartridge heater can be used. The cooling cylinder 56 has, for example, a cylindrical shape, and a plurality of cooling fins 57 extending radially in the radial direction are provided on the outer peripheral wall in order to cool the wall portion. In this embodiment, the cooling cylinder 56 is air-cooled by the heat radiation action from the fins 57. However, a forced air cooling system in which air is blown and cooled by a fan (not shown), or a water-cooled pipe is wound instead of the fins 57. It is also possible to adopt a water cooling method for cooling.

  When energization of the heater 54 is started by the control of the control device 9, the diffusion oil 53 is heated, and the heated diffusion oil 53 evaporates (vaporizes), rises inside the chimneys 52a and 52b, and is provided thereon. The nozzles 55a and 55b are ejected at a supersonic speed radially outward and obliquely downward. Gas molecules such as air that have jumped into the jet of the diffusion oil 53 collide with heavy vapor molecules having a large momentum of oil and are splashed in the direction of the boiler 51, and as a result, flow into the discharge port 59 provided in the vicinity of the boiler 51. And is discharged from the discharge port 59. Since the oil rotary vacuum pump 4 is connected in series to the discharge port 59 via the vacuum pipe 6, the oil rotary vacuum pump 4 effectively assists the discharge of air. On the other hand, when the supersonic oil vapor jet reaching the cooling cylinder 56 collides with the inner wall of the cooling cylinder 56, a shock wave is generated and the pressure is recovered at once to return to a normal vapor state. At the same time, by colliding with the inner wall of the cooling cylinder 56, most of the steam is liquefied and falls, and returns to the inside of the boiler 51. By repeating these steps, the oil diffusion vacuum pump 5 can depressurize (evacuate) the connected rotary chamber 3. Therefore, the oil diffusion vacuum pump 5 is provided with a heater 54 that heats the oil and a cooling cylinder 56 that returns the oil vapor jet to normal vapor or liquid, and controls the heated diffusion oil to evaporate efficiently. This is very important.

  The inventors of the present application focused on the above-described operation control of the oil diffusion vacuum pump 5 in the temperature difference between the upper and lower sides sandwiching the fins 57 of the cylindrical cooling cylinder 56. In the oil diffusion vacuum pump 5 according to the present embodiment, the temperature sensor 10 is provided on the lower side (side closer to the boiler 51) of the cooling cylinder 56, and the temperature sensor is further provided on the upper side (counter boiler 51 side) of the cooling cylinder 56. 11 was provided. When the detection values of the temperature sensors 10 and 11 are monitored, the temperature sensor 10 close to the boiler 51 filled with the diffusion oil 53 exhibits a higher temperature value when the heater 54 is energized. Further, the temperature sensor 11 exhibits a temperature value lower than that of the temperature sensor 10 due to the heat radiation action by the fins 57. The inventor has found that the temperature difference between the temperature sensors 10 and 11 is substantially constant regardless of the room temperature (the temperature detected by the temperature sensor 14). This phenomenon will be described below.

FIG. 3 is a graph showing the relationship between the elapsed time and the pressure in the rotating chamber 3 when the oil diffusion vacuum pump 5 and the oil rotary vacuum pump 4 are operated. A solid line 31 is a state when the room temperature (temperature detected by the temperature sensor 14 in FIG. 1) is 35 ° C., a broken line 32 is a state when the room temperature is 25 ° C., and a dotted line 33 is a state when the room temperature is 15 ° C. The one-dot chain line 34 is a state when the room temperature is 5 ° C. As can be understood from this figure, when the oil diffusion vacuum pump 5 and the oil rotary vacuum pump 4 are operated at any room temperature, the pressure in the rotary chamber 3 is reduced smoothly and equally, regardless of the room temperature. Around the minute, the pressure in the rotating chamber 3 reaches 1.33 Pa. After the pressure is reduced to a predetermined pressure (after the time t ₁ ), the change in the pressure reduction varies depending on the room temperature. This is because the pressure around this was the accuracy limit of the pressure gauge used (for example, Pirani gauge). is there. According to the inventor's experiment, the display value of the Pirani gauge near the time t ₁ is 0.6 Pa when the room temperature is 35 ° C., 0.4 Pa when the room temperature is 25 ° C., 0.2 Pa when the room temperature is 15 ° C., It was 0.0 Pa at room temperature of 5 ° C. As described above, the inventors' experiments have revealed that the reduced pressure state is the same when the oil diffusion vacuum pump 5 and the oil rotary vacuum pump 4 are operated regardless of the room temperature.

  Usually, since the centrifuge 1 is often placed in a room with an air conditioner, the centrifuge 1 often operates at a constant temperature, but the temperature change is severe as after the air conditioner has stopped. In some cases, it can be operated at For example, the operation of the centrifuge 1 is started in a state where the outside air temperature (the temperature of the part controlled by the air conditioner) is high because the air conditioner is not sufficiently operated and the centrifuge 1 is placed, as in the morning after a midsummer holiday. In such a case, the room temperature of the centrifuge 1 gradually decreases with the outside air temperature due to the operation of the air conditioning equipment after the start of operation. Accordingly, there is a change in the room temperature when the time t1 has passed after the operation, and in the conventional technology, there is a possibility that appropriate management of an appropriate reduced pressure state cannot be performed unless control is performed in consideration of the change in the room temperature. Similarly, the same situation can occur in the morning after a mid-winter holiday. In order to cope with such a short-time change in room temperature, the inventor has provided temperature sensors at various locations where the temperature difference of the oil diffusion vacuum pump 5 occurs, and as a result of verifying the relationship between those temperatures, FIG. I found a fact like 4.

  FIG. 4 is a graph showing the relationship between the temperature detected by the temperature sensors 10 and 11 and the elapsed time when the oil diffusion vacuum pump 5 is operated. The output group 39 is a graph of the temperature detected by the temperature sensor 10, the solid line 35 is the state when the room temperature (the temperature detected by the temperature sensor 14 in FIG. 1) is 35 ° C., and the broken line 36 is the room temperature 25 The dotted line 37 is the state when the room temperature is 15 ° C, and the alternate long and short dash line 38 is the state when the room temperature is 5 ° C. On the other hand, the output group 45 is a graph of the temperature detected by the temperature sensor 11, the solid line 41 is the state when the room temperature (the temperature detected by the temperature sensor 14 in FIG. 1) is 35 ° C., and the broken line 42 is the room temperature. Is a state when the room temperature is 15 ° C., and a one-dot chain line 44 is a state when the room temperature is 5 ° C.

  What can be understood from this graph is that both the temperature sensors 10 and 11 rise as seen by arrows 40 and 46 as the room temperature rises. However, the inventor has found that the degree of the rise is almost the same as the temperature difference between the temperature sensors 10 and 11. The graph of FIG. 5 is re-plotted to verify this relationship. FIG. 5 is a diagram showing the relationship between the temperature difference (Δt) between the temperature sensors 10 and 11 and the elapsed time (min). Immediately after the oil diffusion vacuum pump 5 is operated, the temperature difference Δt between the temperature sensors 10 and 11 is almost zero. Although the temperature difference increases with the lapse of time after the operation, as can be understood from FIG. 5, the temperature difference is settled to be almost the same regardless of the room temperature. Therefore, if the oil diffusion vacuum pump 5 is controlled using the output difference between the two temperature sensors 10 and 11, the oil diffusion vacuum pump 5 is appropriately controlled without considering the room temperature detected by the temperature sensor 14. Can be done. In this embodiment, this characteristic is used to control the oil diffusion vacuum pump 5 so that the temperature difference Δt between the temperature sensors 10 and 11 becomes a target value. In the control of the oil diffusion vacuum pump 5 of the present embodiment, it is not necessary to use room temperature data detected by the temperature sensor 14, but the room temperature data is used for control of a cooling device (not shown) and the like. It is not preferable to omit the temperature sensor 14.

FIG. 6 is a characteristic graph showing a measurement example of the temperature difference detected by the temperature sensor of the centrifuge 1 and the rotation chamber pressure. In this graph, a plurality of measured values are taken, and the upper limit value 65a and the lower limit value 65b are shown in a certain range, and the ranges are indicated by hatched lines 65. As shown in FIG. 6, a certain temperature difference between the boiler temperature and the cooling wall is necessary to reduce the pressure inside the rotary chamber 3 to a certain pressure or less. For example, a temperature difference of T _13.3 or more is necessary in order to make the pressure inside the rotating chamber 3 _13.3 Pa or less. Conversely, when the temperature difference Δt has reached T _13.3 or more, it can be seen that the atmospheric pressure inside the rotating chamber 3 has reached _13.3 Pa or less. Similarly, in order to make the atmospheric pressure inside the rotation chamber 3 1.33 Pa or less, a temperature difference of T _1.33 or more is required. The temperature difference Δt at T _1.33 is, for example, 53 degrees. When the temperature difference Δt reaches T _1.33 , the oil diffusion vacuum pump 5 may be controlled so as not to fall below the temperature difference Δt.

The inventors' experiments have shown that these _T13.3 and _T1.33 values are within a substantially constant range regardless of variations in room temperature if the dimensional structure of the oil diffusion vacuum pump is the same. . Therefore, the temperature sensor 10 and the temperature sensor 11 side are installed on the boiler 51 side and the anti-boiler 51 side across the fins 57 of the cooling cylinder 56, and the temperature difference is read from the signals from the two temperature sensors. By performing feedback control of the temperature of the heater 54 so as to achieve a predetermined temperature difference, it is possible to stably evacuate the rotating chamber 3 regardless of the temperature (installation temperature) of the environment where the centrifuge 1 is placed. .

  Next, the control procedure of the oil diffusion vacuum pump 5 in the centrifuge of the present invention will be described with reference to the flowchart shown in FIG. First, when a switch instructing the operation start of the operation unit 13 is pressed (step 71), an operation start signal is input to the control device 9, the operation of the oil rotary vacuum pump 4 is started, and the inside of the rotary chamber 3 is started to be depressurized. . At the same time, the heater 54 of the oil diffusion vacuum pump 5 begins to heat the diffusion oil 53 with full power (step 72). When the operations of the two vacuum pumps are started, the pressure (degree of vacuum) in the rotating chamber 3 gradually decreases from the atmospheric pressure. On the other hand, since the heater 54 of the oil diffusion vacuum pump 5 is turned on, the temperature of the boiler 51 rises with time. There are two conditions for the oil diffusion vacuum pump 5 to start operation, one of which is that the degree of vacuum is below the required back pressure (critical back pressure), and the other is the boiler temperature. Has reached a certain value, that is, the boiling temperature of the internal oil. Therefore, in order for the oil diffusion vacuum pump 5 to start operation, it is important to sufficiently heat the boiler temperature at an early stage. This time becomes longer when the boiler temperature of the oil diffusion vacuum pump (DP) is lowered to about room temperature, for example, when the centrifuge 1 is first operated on the day. On the contrary, when the boiler temperature is sufficiently high due to the immediately preceding centrifugal separation operation as in the case where the centrifugal separation operation is continuously performed, the time is shortened.

  Next, the drive device 8 is driven to start the rotation of the rotor 2 at a low speed (step 73). The rotation of the rotor 2 is increased to the set high-speed rotation after confirming that the inside of the rotation chamber 3 is depressurized to some extent (for example, 13.3 Pa) by the vacuum gauge 12. When the diffusion oil 53 starts to be heated, temperature detection of the temperature sensors 10 and 11 by the control device 9 and counting of the heating time to the heater 54 are started (step 74). In this embodiment, the diffusion oil 53 is heated at the full power of the heater 54 until the difference between the detection values of the temperature sensors 10 and 11 reaches a predetermined value, and when the difference between the detection values reaches a predetermined range, the heater 54 is energized. Is controlled by PID feedback control and pulse width control so that the temperature difference has a certain width. Thus, since the heater 54 is operated with full power when the diffusion oil 53 is heated, the diffusion oil 53 can be heated in the shortest time.

  Next, it is determined whether or not a predetermined time has elapsed since the heater 54 started heating the diffusion oil 53 (step 75). If the predetermined temperature difference cannot be obtained even after the predetermined time has elapsed, there is a possibility that the required amount of the diffusion oil 53 does not exist, or that a malfunction due to deterioration of the diffusion oil 53 occurs. Therefore, if the predetermined time has elapsed, an error is displayed on the operation unit 13 (step 80), and the process proceeds to step 80 to stop the rotation of the rotor 2.

If the heater has not been heated for a predetermined time in step 75, it is determined whether the temperature difference detected by the temperature sensors 10 and 11 is smaller than a predetermined value (step 76). Here, the temperature indicated by _T1.33 in FIG. 6 may be set as the predetermined value. By setting _T1.33 as the predetermined position, it can be indirectly determined that the pressure inside the rotating chamber 3 is higher than 1.33 Pa until this temperature difference is reached. When the temperature difference detected by the temperature sensors 10 and 11 becomes equal to the predetermined value in step 76, the process returns to step 74 while maintaining the state where the heating power to the heater 54 is 100% (step 77). When the temperature difference detected by the temperature sensors 10 and 11 reaches a predetermined value in step 76, the energization of the heater 54 is controlled so that the temperature difference detected by the temperature sensors 10 and 11 becomes equal to the predetermined value ( Step 78). At this time, the method of controlling the heater 54 is arbitrary, but for example, switching to PID feedback control or pulse width control may be performed so that the oil temperature stays within a certain range centered on a predetermined position.

  Next, it is determined whether or not the rotor 2 has rotated at a set speed for a predetermined time (= centrifugation time). If it has not elapsed, the process returns to step 78, and if it has elapsed, the centrifugation operation is terminated. This means that the process proceeds to step 81 (step 79). In step 81, the rotation of the drive device 8 is stopped to stop the rotation of the rotor 2 (step 81). When a vacuum release switch (not shown) of the operation unit 13 is pressed (step 82), the oil diffusion vacuum is performed. The heating of the diffusion oil 53 is stopped by stopping energization of the heater 54 of the pump 5 (step 83). Similarly, the operation of the oil rotary vacuum pump 4 is stopped (step 84), a leak valve (not shown) is opened to bring the atmosphere into the rotation chamber, and the inside of the rotation chamber 3 is returned to the same atmospheric pressure as the atmosphere. The process ends.

  As described above, according to the embodiment of the present invention, the temperature sensor is provided in the low temperature part and the high temperature part of the cooling part of the oil diffusion vacuum pump, and the temperature difference is used to control the heater so that the ambient temperature of the centrifuge is adjusted. Regardless of the temperature, the oil diffusion vacuum pump can be controlled. In addition, a stable centrifuge operation is possible without being affected by the temperature change of the installation environment temperature of the centrifuge.

  In order to confirm the effect of the present embodiment, the inventor puts the centrifuge 1 in a constant temperature room and lowers the room temperature from 30 ° C. to 10 ° C. by 1 ° C. per minute. The pressure in the rotating chamber 3 when the room temperature was lowered was measured. In the conventional control method of the oil diffusion vacuum pump 5 based on the room temperature, the pressure of the rotating chamber was increased from the time when the heater temperature was increased to the time of stabilization at a rate of once every two times. In the case of control by the low temperature side temperature sensor 10 and the high temperature side temperature sensor 11 of the cooling cylinder 56 of the vacuum pump 5, no pressure increase in the rotating chamber 3 was observed. Thereby, it was confirmed that the control method of the oil diffusion vacuum pump according to the present invention is not affected by the change in room temperature.

  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 the above-described embodiment, the location where the temperature sensors 10 and 11 are installed by the oil diffusion vacuum pump 5 is relatively arbitrary as long as the position of the temperature sensor on the low temperature side is a position where a cooling effect can be obtained by fins or cooling cylinders. The temperature sensor on the side may be provided at a position closer to the boiler, or may be attached to the boiler casing. Further, the temperature sensor 10 may be attached to a cooling fin like the temperature sensor 110 of FIG. 8, and the temperature sensor 11 may be attached to the uppermost fin among the cooling fins.

1 Centrifuge 2 Rotor 3 Rotating chamber
DESCRIPTION OF SYMBOLS 4 Oil rotary vacuum pump 5 Oil diffusion vacuum pump 6, 7 Vacuum piping 8 Drive apparatus 9 Control apparatus 10, 11 Temperature sensor 12 Vacuum gauge 13 Operation part 14 Temperature sensor 51 Boiler 52a, 52b Chimney 53 Diffusion oil 54 Heater 55a, 55b Nozzle 56 Cooling cylinder 57 Fin 59 Discharge port 101 Centrifugal machine 102 Rotor 103 Rotating chamber 104 Oil rotary vacuum pump 105 Oil diffusion vacuum pump 106, 107 Vacuum piping 108 Drive device 109 Control device 110 Temperature sensor 112 Vacuum gauge 113 Operation unit 114 Temperature sensor 154 Heater

Claims (8)

In a centrifuge having a drive device, a rotor that is rotated by the drive device and holds a sample, a rotary chamber that houses the rotor, and an oil diffusion vacuum pump that depressurizes the rotary chamber to a predetermined vacuum,
First and second temperature sensors are provided at two locations in the oil diffusion vacuum pump where the temperature difference occurs in the cooling section of the diffusion oil,
The centrifugal separator characterized by controlling energization to the heater of the oil diffusion vacuum pump using the temperature difference detected by the first and second temperature sensors.   2. The centrifugal separator according to claim 1, wherein the first and second temperature sensors are provided at two locations separated in a vertical direction of the outer wall of the cooling portion in a cylindrical shape. A plurality of cooling fins extending in the radial direction are provided at a substantially central portion in the vertical direction of the cooling unit,
The first temperature sensor is provided on a cooling unit outer wall below the cooling fin, and the second temperature sensor is provided on a cooling unit outer wall above the cooling fin. The centrifuge described in 1. A plurality of cooling fins extending in the radial direction are provided at a substantially central portion in the vertical direction of the cooling unit,
The centrifuge according to claim 2, wherein the first temperature sensor is provided in the lower cooling fin, and the second temperature sensor is provided in the upper cooling fin. After starting the oil diffusion vacuum pump, energizing the heater with full power until the temperature difference detected by the first and second temperature sensors reaches a predetermined value,
5. The control according to claim 1, wherein when the detected temperature difference reaches a predetermined value, control is performed so as to maintain the detected temperature difference at a predetermined value by adjusting energization to the heater. The centrifuge described.   6. The centrifugal separator according to claim 5, wherein the energization to the heater is feedback controlled so that the detected temperature difference is maintained at a predetermined value.   Even if a certain time has elapsed after the start of energization of the heater, if the temperature difference detected by the first and second temperature sensors does not reach a predetermined temperature difference, the energization of the heater is stopped. The centrifuge according to claim 6. An oil rotary vacuum pump is provided in series with the oil diffusion vacuum pump,
The centrifuge according to any one of claims 1 to 7, wherein when the rotation chamber reaches a first degree of vacuum, the rotor is accelerated to a set number of rotations.

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