JP7274383B2 - Centrifuge - Google Patents

Description

The present invention relates to a centrifuge for centrifuging a sample by rotating a rotor in which the sample is inserted.

A centrifuge inserts a sample to be separated (for example, culture medium, blood, etc.) into a rotor via a tube or bottle, and rotates the rotor at high speed to separate and purify the sample. The rotational speed of the rotor to be set varies depending on the application, and product groups ranging from low speed (about several thousand rotations) to high speed (maximum rotation speed is 150,000 rpm) are provided according to the application. When a sample is separated by a centrifuge, a rotor suitable for the purpose of sample separation is used, and centrifugal conditions such as rotation speed, operating time, and rotation chamber temperature are set for the centrifuge. There are methods such as a method in which the rotor is simply placed on the rotating shaft of the centrifuge, and a method in which the rotor is fixed to the rotating shaft using screws or the like.

Some types of rotors have a lid-like cover on the top to reduce windage loss and wind noise. Buoyancy is generated in the rotor due to the fan action due to the unevenness of the rotor, and the rotor floats up and is about to separate from the rotating shaft, resulting in an unstable state. In order to avoid such an inconvenience, there is a method of fixing the rotor to the rotating shaft of the motor using screw tightening means, but the above problem occurs if the operator forgets to tighten the screw. For this reason, there is a conventionally known technique in which a length measuring device is provided on a door that closes a rotating chamber to measure the distance between the inner wall surface of the door and the rotor to determine whether or not the cover is attached.

As one method of the length measuring device, a method of measuring the time from when an ultrasonic wave is emitted to when the reflected wave returns has been put into practical use, as described in Patent Document 1. An ultrasonic sensor is installed inside the door to both emit and detect sound waves, and the time it takes for the sound waves emitted toward the rotor to reflect off the top surface of the rotor and return to the ultrasonic sensor again is measured. The distance is calculated by multiplying the value. In calculating the distance, it is necessary to measure the air temperature and use the sound velocity value according to the temperature. Since a conventional centrifuge is provided with a temperature sensor for measuring the temperature in the rotating chamber, the sound velocity value is obtained from the corrected temperature value by correcting the detection value of the temperature sensor in order to obtain the above-described sound velocity value. This is described in Patent Document 1.

A conventional centrifuge will now be described with reference to FIG.
A plurality of magnets 20 are embedded in the bottom of the rotor 4 in a circumferential shape, and a hall IC 21 is provided on the upper part of the motor facing the magnets. ing. A thermistor 7a and a thermistor 7b are provided at the bottom of the rotor chamber 3. As shown in FIG. As for the relationship between the temperature of the thermistor 7a and the rotor temperature, the temperature control data for each rotor type is stored in advance in the controller 18, and the temperature of the thermistor 7a is adjusted to the target temperature by the refrigerating device in order to achieve the rotor temperature set by the user. is controlled to control the rotor temperature. If an abnormality occurs in the thermistor 7a or the circuit, the temperature of the rotor 4 cannot be properly controlled. If this occurs, it is determined that a thermistor or circuit failure has occurred, and an alarm is issued to stop the operation. An ultrasonic sensor 25 is provided at the center of the door 6, and measures the distance from the ultrasonic sensor 25 to the rotor 4 when the door 6 is closed. A rotor cover 5 is attached to the rotor 4, and the controller 18 stores data in advance for each rotor type regarding the distance from the ultrasonic sensor 25 to the rotor 4 or the rotor cover 5 when the rotor cover 5 is attached and when the rotor cover 5 is not attached. , and the presence or absence of the rotor cover 5 is identified before driving by comparing with the measured distance.

JP 2013-144285 A

However, in the conventional centrifuge, when there is an abnormality in the thermistor, its circuit, etc., the thermistor 7b, its cable, etc., for detecting abnormality as shown in FIG. was necessary and costly.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a convenient centrifugal separator while suppressing an increase in cost.

According to one feature of the present invention, it comprises a rotor for holding a sample, a motor for rotating the rotor, a bowl for housing the rotor, a door for closing an opening of the bowl, and the bowl and the door. a rotor chamber, a temperature sensor for detecting the temperature in the rotor chamber, a reference point for the rotor chamber, a distance sensor provided in the rotor chamber for measuring the distance to the reference point, and controlling the motor and a control device, wherein the control device uses the distance sensor to measure the distance between the distance sensor and the reference point, and determines whether the temperature sensor is abnormal based on the measured distance. I tried to judge.

ADVANTAGE OF THE INVENTION According to this invention, the convenient centrifuge can be implement|achieved, suppressing an increase in cost.

1 is a cross-sectional view showing an overall structure according to an embodiment of the present invention; FIG. FIG. 4 is a diagram showing the relationship of sound speed to air temperature according to an embodiment of the present invention; FIG. 5 is a cross-sectional view showing the relationship between the thermistor temperature and the distance A according to the embodiment of the present invention; It is a sectional view showing the whole structure in the conventional centrifuge.

Embodiments of the present invention will be described below with reference to the drawings. In the drawings below, the same parts are denoted by the same reference numerals, and repeated descriptions are omitted.

As shown in FIG. 1, a centrifuge 1 has a bowl 2 inside a housing 11 made of box-shaped sheet metal or the like. can be rotated in the vertical direction with the front side as the central axis. The rotor chamber 3 is provided with an opening 3a on the upper side so that the rotor 4 can be attached or removed. Further, a door packing 16 is provided around the opening 3a, and when the door 4 is closed, the door 4 and the door packing 16 are in close contact with each other, so that the rotor chamber 3 is hermetically sealed.

Legs 13 are provided at the four lower corners of the housing 11 , and a partition plate 12 extending horizontally is provided near the center of the housing 11 . A bowl 2 is provided in a space above the partition plate 12 , and a motor 8 as a driving device is fixed via a damper 22 . A rotating shaft 8a of a motor 8 extends from a through hole 2a in the bottom surface of the bowl 2 into the rotor chamber 3, and a rotor 4 is detachably attached to a crown 8b provided at the tip of the rotating shaft 8a. The rotor 4 has a plurality of holes for inserting a sample container (not shown) for containing a sample, and is rotated at high speed by a motor 8 to separate the sample.

A rotor cover 5 is attached to the upper portion of the rotor 4 to avoid the influence of windage during rotation. The rotor cover 5 is a part of the rotor 4 and is always attached by screws during centrifugal operation.

Behind the door 6, an operation panel 19 is arranged for the user to input conditions such as the set rotation speed of the rotor, the separation time, the set temperature, etc., and to display various information. The operation panel 19 is composed of, for example, a combination of a liquid crystal display device and operation buttons or a touch-type liquid crystal panel, and functions as an input device and an information display device.

A copper pipe 17 c is spirally wound around the outer circumference of the bowl 2 , and the outer circumference of the copper pipe 17 c is surrounded by a cylindrical heat insulating material 14 . Furthermore, a protector 23 made of steel is provided on the outer periphery. The copper pipe 17c constitutes a part of the cooling device. Refrigerant is sent from the compressor 17b into the condenser 17a, and the refrigerant cooled by the condenser 17a and the blower 10 is liquefied. The liquefied refrigerant is supplied to the copper pipe 17c through the capillary 17d, and the inside of the rotor chamber 3 is controlled by the control device 18 during the centrifugal separation operation so that it reaches the set temperature input from the operation panel, and the rotor 4 is kept constant. kept at a temperature of At this time, the temperature of the rotor 4 is monitored by the controller 18 using the output of the temperature sensor (thermistor) 7 installed in the rotor chamber 3 .

A plurality of magnets 20 are embedded in the bottom of the rotor 4 in a circumferential shape, and a hall IC 21 is provided on the upper part of the motor facing the magnets. ing. A thermistor 7 is provided at the bottom of the rotor chamber 3 . Regarding the relationship between the temperature of the thermistor 7 and the rotor temperature, the temperature control data for each rotor type is stored in advance in the controller 18, and the temperature of the thermistor 7 is used to set the rotor temperature set by the user. is controlled to reach the set temperature.

A hook catch 6a is provided on the lower surface of the door 6, and the door lock mechanism 30 keeps the door 6 closed by restricting the vertical movement of the hook catch 6a. In the centrifuge 1 of the present embodiment, when the start button is pressed by the user to start the centrifugal separation operation, the control device 18 locks the door lock mechanism 30, the centrifugal separation operation is completed, and the rotor 4 is When the rotation stops, the door lock mechanism 30 is unlocked.

An ultrasonic sensor ( A sound wave sensor) 25 was provided. An inexpensive length measuring device composed of a combination of the control device 18 for controlling the ultrasonic sensor 25 is used and accommodated in the center of the door 6 . The control device 18 oscillates and drives the ultrasonic sensor 25 to output sound waves downward from the ultrasonic sensor 25, and the ultrasonic sensor 25 senses the sound waves bounced off the surface of the rotor 4 or the rotor cover 5 serving as the reference point. receive.

The sound wave (reflected wave) received by the ultrasonic sensor 25 is output to the control device 18, and the control device 18 controls the time from when the ultrasonic sensor 25 emits the sound wave to when the ultrasonic sensor 25 receives the reflected wave. The time is measured, and the distance A from the ultrasonic sensor 25 to the upper surface of the rotor 4 or rotor cover 5 is measured using a predetermined formula.

Here, for the rotor 4 attached to the centrifuge 1, the type, size, whether the rotor cover 5 is attached or not, and the standard distance value when the rotor cover 5 is attached are stored in the controller 18 in advance. Therefore, when the door 6 is closed after the rotor 4 is installed and the type of the rotor 4 is identified, the distance A is measured using the ultrasonic sensor 25, and the rotor cover 5 of the rotor 4 whose distance A is identified is removed. Whether or not the rotor cover 5 is attached can be determined by determining whether or not it matches the standard distance B (distance stored in advance in the storage unit of the control device) in the attached state.

In this embodiment, in addition to checking whether or not the rotor cover 5 is attached before starting operation, the distance A is measured by the ultrasonic sensor 25 even during operation to detect abnormalities that occur during operation.

The speed of the sound waves emitted by the ultrasonic sensor 25 changes as shown in FIG. 2 depending on the temperature in the rotor chamber. Therefore, the distance A measured by the ultrasonic sensor 25 changes according to the temperature change in the rotor chamber 3 . Normally, the temperature of the thermistor 7 and the distance A calculated by the ultrasonic sensor 25 have a relationship as shown in FIG.

However, for example, if the thermistor 7 is disconnected, the controller 18 will recognize the temperature inside the rotor chamber 3 as -40°C even if the actual temperature inside the rotor chamber 3 is 20°C.
As a result, the control device 18 cannot operate the cooling device 7 normally, so it is necessary to detect that the thermistor 7 is abnormal.

Therefore, focusing attention on the fact that the distance measurement by the ultrasonic sensor 25 changes depending on the ambient temperature, failure of the thermistor 7 can be detected.
As described above, when an environment that is originally 20° C. is erroneously detected as -40° C. due to a failure (disconnection) of the thermistor 7, the measured temperature of the thermistor 7 and the ultrasonic sensor 25 shown in FIG. The relationship of distance A should be point D (measured temperature of thermistor: 20°C, distance A: about 0.1375m), but it becomes point E (measured temperature of thermistor: -40°C, distance A: about 0.1375m). Since the relationship is outside the range C, it can be recognized as abnormal. Further, from the distance A (0.1375 m) at that time, it can be calculated that the actual temperature in the rotor chamber is about 20° C., so that the controller can determine that the thermistor 7 is abnormal.

In order to prevent the rotor from overheating due to a malfunction of the cooling device, etc., the control device judges that there is a rotor high temperature abnormality (high temperature abnormality in the rotor chamber 3) by the control device when it detects a temperature of 50 ° C or more, and the operation of the centrifuge is stopped. controlled to stop. If an environment that is originally 50°C is misdetected as 20°C due to a failure of the thermistor 7, etc., point G instead of point F (thermistor measurement temperature: 50°C, distance A: about 0.145 m) should be reached. (thermistor measurement temperature: 20° C., distance A: about 0.145 m), which is out of the range C, so it can be recognized that the thermistor 7 is abnormal. Further, since it can be calculated that the actual temperature in the rotor chamber is about 50° C. from the distance A (0.145 m) at that time, the operation of the centrifuge can be stopped by the control device as the rotor high temperature abnormality.
Here, for convenience of explanation, it is assumed that (thermistor temperature)=(rotor temperature)=(rotor room air temperature).

Further, if the rotor cover 5 screwed to the rotor 4 is insufficiently tightened and an abnormality such as loosening of the screw fixing of the rotor cover 5 occurs during operation, the distance A measured by the ultrasonic sensor 25 will be shortened. (H point), when the distance A deviates from the range C before the rotor cover 5 is separated, an abnormality can be detected and the operation of the centrifuge can be stopped.

Therefore, according to the present embodiment, by measuring the distance A using the ultrasonic sensor 25 even during operation, it is possible to detect the rotor error caused by an abnormality such as disconnection of the thermistor 7, a circuit abnormality, or a failure of the cooling device 17 during operation. It is possible to prevent damage to the sample due to uncontrollable temperature. Further, loosening of the rotor cover 5 screw-fixed to the rotor 4 can also be detected before it is separated from the rotor 4 .

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, in the above example, the rotor cover 5 is used as the rotor 4, but the present invention can be similarly applied to a rotor of a type that does not use the rotor cover 5. Furthermore, the present invention can be similarly applied to the case of using not only the angle rotor as described above but also a swing rotor.
Furthermore, in order to measure the air temperature in the chamber, it is not always necessary to measure the distance to the rotor. may be provided.
Furthermore, although the ultrasonic sensor 25 was used as the length measuring device in the description, any sensor may be used as long as the measurement distance changes according to temperature changes. A length measurement sensor may be used.

1: Centrifuge 2: Bowl 2b: Bowl bottom 3: Rotor chamber 4: Rotor 5: Rotor cover 6: Door 6a: Hook catch 7: Thermistor 7a: Thermistor 7b: Thermistor 8: Motor 8a: Rotary shaft 8b: Crown 9: Hinge 10 Blower 11: Case 12: Cutting plate 13: Leg 14 Heat insulating material 16: Door packing 17: Cooling device 17a: Condenser 17b: Compressor 17c: Copper pipe 17d: Capillary 18: Control device 19: Operation panel 20: Magnet 21: Hall IC 22: Damper
23: protector 25: ultrasonic sensor 30: door lock mechanism

Claims (8)

a rotor holding the sample;
a motor that rotates the rotor;
a bowl that houses the rotor;
a door closing the opening of the bowl;
a rotor chamber composed of the bowl and the door, and a temperature sensor for detecting the temperature in the rotor chamber;
a reference point of the rotor chamber and a distance sensor provided in the rotor chamber for measuring a distance to the reference point;
In a centrifuge having a control device that controls the motor,
The control device uses the distance sensor to measure the distance between the distance sensor and the reference point, and determines whether the temperature sensor is abnormal based on the measured distance. . 1. The controller determines whether the temperature sensor is abnormal by calculating the temperature in the rotor chamber based on the measured distance and comparing it with the temperature of the temperature sensor. Centrifuge as described. 2. The centrifuge according to claim 1, wherein said temperature sensor is a thermistor. 2. The centrifuge according to claim 1, wherein said reference point is the upper surface of said rotor. 2. The centrifuge of claim 1, wherein said reference point is the bottom surface of said bowl. 2. The centrifuge according to claim 1, wherein said distance sensor is provided on said door. 2. The centrifuge according to claim 1, wherein said distance sensor is an ultrasonic sensor. 2. The centrifuge according to claim 1, wherein the distance between said distance sensor and said reference point is measured while said rotor is rotating.

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