JP2005111418A - centrifuge - Google Patents

Abstract

【Task】
The present invention reduces the failure of a drive device in a short period of time in a drive device having a plurality of rotating shafts due to corrosion of the drive device bearings due to spilled or leaked sample or moisture adhering to condensed water. That is.
[Solution]
In a drive device having a plurality of rotating shafts, it can be realized by adopting a highly dustproof and waterproof bearing for a rigid shaft bearing.
[Selection] Figure 1

Description

  The present invention relates to a drive device for a device such as a centrifuge used in medicine, pharmacy, agriculture, etc., in which the periphery of a rotating shaft is easily exposed to sample leakage or condensed water due to cooling.

  A conventional centrifuge transmits rotational torque obtained by a driving device such as an electric motor to a rotor via a rotating shaft, and rotates the rotor. The rotor used in this type of centrifuge includes an angle rotor in which the angle of the test tube hole into which the sample is inserted is constant, a swing rotor in which a container (called a bucket) in which the test tube is mounted swings with rotation, and a test tube There are several types, such as a horizontal rotor that is attached to the rotor in a horizontal state. In addition, in order to avoid centrifugal breakage, a rotor with a high permissible rotational speed is generally small in appearance and shape, and a low rotor is generally large in appearance and shape. In particular, the above-described swing rotor can be rotated at a high speed due to strength limitations. Difficult, characterized by processing capacity.

  On the other hand, when designing a rotating shaft, in general, when the rotational speed is high, a so-called elastic shaft that lowers the bending rigidity of the rotating shaft and gives the natural frequency of bending to a low speed region is adopted. The dynamics of the body, R. Gash / H. Pützner, original translation by Shuzo Miwa, Morikita Publishing) are considered to reduce the reaction force due to unbalance on the high speed side. In addition, in order to enable the use of a large rotor as described above, although the rotational speed is low, a so-called rigid shaft that increases the rigidity of the rotating shaft to give the bending natural frequency faster than the operating range is provided. Adopted to improve operability with high rigidity.

  From the above, when the high-speed rotor and the low-speed large rotor can be used in a single centrifuge, the elastic shaft can be used to obtain stable rotation at high speed, but the shaft rigidity is low. When the rotor is attached to the rotary shaft, the rotary shaft is easily bent, and in some cases, the rotary shaft may be bent. In addition, since the rotor with a large capacity causes a greater disparity in the sample handled by the user, when the large swing rotor is rotated by the elastic shaft, the primary natural frequency (primary resonance point) of bending of the rotating shaft As a result, the rotating rotor may come into contact with the fixed part or the rotating shaft may be bent. That is, when an elastic shaft is employed, the high-speed rotor is easy to use, but the low-speed swing rotor is generally poorly handled.

  In order to make up for such drawbacks, International Publication No. WO02 / 085526 has proposed a centrifuge drive device which has a plurality of rotating shafts and can select the rotating shafts depending on the rotor used. However, the drive device for the centrifuge is usually mounted so as to protrude into the rotor chamber where the rotor rotates. For this reason, the portion protruding into the rotor chamber of the drive unit may be exposed to a sample in which the tube containing the sample is broken during the rotation due to centrifugal force and leaked or a sample accidentally spilled by the customer. In addition, a type equipped with a refrigerator and capable of cooling the rotor is exposed to water due to condensation. In this case, dew condensation occurs not only on the outer surface of the drive device but also on the inside of the drive device by cooling the protruding portion, and the possibility of corrosion increases.

Here, the conventional centrifuge drive device 41 has only one rotating shaft 42 as shown in FIG. 4, and a crown 43 is disposed at the tip thereof, and a sample container 45 containing a sample. The rotor 44 in which is inserted is detachably connected and supported.
Since the bearing that normally supports the rotating shaft could be positioned away from the rotor, a labyrinth portion 51 (between the crown 43 and the shaft case 46) as shown in FIG. 5 is provided in the space from the rotor chamber to the bearing. It was also relatively easy, and it was possible to make sure that leaked or spilled samples did not reach the bearings. As for condensation, the shaft case 46, which is a part of the housing protruding into the rotor chamber, does not apply a large force. Therefore, it is possible to select a separate material such as a resin that has a small heat capacity and hardly causes condensation.

  Furthermore, in Japanese Utility Model Laid-Open No. 2-1255752, by providing a hook-like protrusion on the motor cover, even if the centrifuge is operated with water accumulated in the lower part of the rotor chamber, water can be prevented from entering the motor. It has been proposed to prevent the corrosion and deterioration of the bearing.

International Publication Number WO02 / 085526

Actual Kaihei No. 2-125752

On the other hand, in the above-described centrifuge drive device having a plurality of rotating shafts, the rigid shaft is disposed between the rotor and the crown as shown in FIG. 1 and supported by the upper housing via a bearing. Here, the upper housing receives a force from the rigid shaft. In addition, the bearing that supports the rigid shaft needs to be as close to the crown taper portion of the rigid shaft that receives the unbalanced force of the rotor as possible so that it is not easily affected by the tilting of the rigid shaft due to the unbalanced force of the rotor.
Therefore, due to these structural restrictions, the centrifuge drive device having a plurality of rotating shafts cannot place the rigid shaft bearings away from the rotor, so that the labyrinth portion cannot be provided. It is also difficult to make the upper housing protruding into the rotor chamber from resin due to strength restrictions.

  Furthermore, in the centrifugal separator having the conventional structure described in Patent Document 2, although water entering the motor cover surface can be prevented, water entering the rotating shaft and water scattered in the rotor chamber can be prevented. I can't.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an improved corrosiveness to a sample of a portion projecting from a rotor chamber and condensed water in a drive device for a centrifuge having a plurality of rotating shafts. .

  The above object is achieved by adopting a contact seal bearing having high dustproof and waterproof properties for the bearing on the rigid shaft side.

  According to the present invention, corrosion of the drive device can be prevented from spilled or leaked sample or condensed moisture, and the life of the drive device can be extended.

FIG. 1 shows an embodiment in which a high-speed angle rotor is attached to the left half and a low-speed swing rotor is attached to the right half. FIG. 3 shows another embodiment of the present invention.
1 and 3 show a state in which a high-speed angle rotor is attached to the left half and a state in which a low-speed swing rotor is attached to the right half for convenience of explanation, the two types of rotors are essentially separate rotors. The actual shape is the shape of the left and right objects.
FIG. 2 is an enlarged view with the rotor removed.

  A horizontally extending partition plate 19 is supported on the body (not shown) of FIG. 1, and an upper chamber 20 is formed by the body (not shown) and the partition plate 19, and a bowl 21 is disposed on the partition plate 19. A heat insulating member 22 is disposed on the outer periphery of the bowl 21. Further, between the bowl 21 and the heat insulating member 22, a refrigerant pipe 23 for circulating a refrigerant sent from a refrigerator (not shown) is disposed in close contact with or adhered to the bowl 21. A door 26 is provided at the upper end opening of the bowl 21 so as to be openable and closable. Furthermore, openings 19a, 21a, 22a are formed in the partition plate 19, the lower center of the bowl 21 and the lower portion of the heat insulating member 22, respectively, and the openings are arranged concentrically.

A driving device 17 for rotationally driving various rotors is inserted and disposed in these openings 19 a, 21 a, and 22 a, and is supported by the partition plate 19 through vibration-proof rubber 25.
The motor shaft 2 having the rotor core 1 of the driving device 17 is supported by the housing 5 and the upper housing 6 through two bearings, a bearing 3 and a bearing 4, and an elastic shaft 7 is connected to the upper part, and further on the upper part. A crown 8 is connected. The rigid shaft 9 has the same axial center as the elastic shaft 7 and is supported by the upper housing 6 via a bearing 10 so as to pass through the elastic shaft 7.
In the drawing of the embodiment, the bearing 10 has a structure in which the outer ring 10a is engaged with the upper housing 6 and the inner ring 10b is engaged with the rigid shaft 9, but the outer ring 10a is engaged with the rigid shaft 9 and the inner ring 10b. May be configured to engage with the upper housing 6.

  A plurality of rotors are prepared so that the rotor can be selected according to the amount of the sample and the conditions for centrifugal separation, and the rotor is detachably connected to and supported by a crown 8 disposed on the upper portion of the driving device 17.

  Rotational torque generated by the drive device 17 is transmitted to the rotor through the elastic shaft 7 and the crown 8 and further by fitting the crown pin 12 and the rotor pin 13 disposed on the rotor. Further, the thrust and radial loads are supported only by the crown 8 in the high-speed angle rotor 14 shown in the left half of FIG. That is, the high-speed angle rotor 14 is supported and rotated only by the elastic shaft.

  On the other hand, in the low-speed swing rotor 15 shown in the right half, the rotational torque is transmitted in the same manner as the high-speed angle rotor, but the thrust and radial loads are supported by the rigid shaft 9 and rotate. For this reason, since the upper housing 6 receives the force (radial direction) generated by the unbalance of the sample placed in the low-speed swing rotor 15 or the sample container 16 through the rigid shaft 9 and the bearing 10, it is usually strong. Uses stainless steel with high corrosion resistance.

  Further, in the bearing 10, a cylindrical outer ring 10a and a cylindrical inner ring 10b having a smaller outer shape than the outer ring are concentrically arranged, and grooves are provided on opposing surfaces of the outer ring 10a and the inner ring 10b. The ball 10c is disposed so that the outer ring 10a and the inner ring 10b can rotate with each other. Further, seal members 10d are disposed at both ends of the outer ring 10a and the inner ring 10b so as to contact both wheels.

Some samples to be centrifuged are centrifuged at a low temperature. For example, the sample is centrifuged while the temperature of the sample is cooled to 4 ° C. For this reason, the centrifuge is provided with an operating condition input unit (not shown), and the set temperature is input as 4 ° C. from the operating condition input unit.
In the centrifuge, based on the input conditions, a control device (not shown) controls the sample in the rotor to a set temperature based on signals from various sensors (not shown). Therefore, the inside of the rotor chamber 18 is maintained at a low temperature.

  Therefore, when the rigid shaft 9 and the upper housing 6 are made of a material having a large heat capacity such as stainless steel, outside air enters the rotor chamber 18 when the door is opened after the operation is finished, and the rigid shaft 9, the surface of the upper housing 6, A large amount of condensed water also adheres to the surfaces of the bowl 21 and the rotors 14 and 15.

When the centrifuge is operated without removing the condensed water adhering to the rigid shaft 9, the upper housing 6, and the rotor chamber 18, the condensed water adhering to the rigid shaft surface as shown in FIG. The scattered dew condensation water flows into the bearing 10 as indicated by the arrow in the entry path 26.
However, since a contact seal type bearing is used, the inside of the bearing cannot corrode because condensed water cannot enter the bearing.

As shown in FIG. 2, the bearing 10 can be directly observed from the upper opening of the rotor chamber 18 in a state where the rotor is removed. If a liquid such as a sample or water is spilled into the rotor chamber 18, or if dust such as dust or metal pieces falls into the rotor chamber 18, there is a possibility of entering the bearing 10. However, by using a contact seal type bearing, it is possible to prevent liquid such as a sample and solid matter such as a metal piece from entering.
The seal member 10d of the bearing need not be provided at both ends of the bearing, and even if the seal member 10d is provided only on one side on the rotor chamber side, water can be prevented from entering the bearing.

  Further, since the contact seal type bearing has a larger loss than the non-contact type bearing, when there are two bearings supporting the rigid shaft 34 on the upper housing 31 as shown in FIG. 3, intrusion of dew condensation water and dust is possible. A contact seal type bearing is selected only for the highly-bearing bearing 10, and a non-contact seal bearing with little rotation loss or a bearing without a seal member may be used as the bearing 38 that is free from the intrusion of liquid and solid matter.

  In addition, a bearing made of a non-magnetic material such as a stainless steel bearing or a ceramic ball bearing may be selected instead of the contact seal type bearing described above, and a stainless steel bearing or a ceramic ball bearing provided with a contact rubber seal. The selection of a highly dustproof and waterproof bearing is also consistent with the gist of the present invention. However, these bearings are generally expensive and the choice of contact rubber seal type bearings is better.

It is a figure which shows the Example of this invention with the partial cross section figure of a centrifuge. FIG. 2 is an enlarged view with the rotor removed in FIG. 1. It is a figure which shows another Example of this invention with the partial cross section figure of a centrifuge. It is a figure which shows the example of the conventional centrifuge with the partial cross section figure of a centrifuge. FIG. 5 is an enlarged view showing details in FIG. 4.

Explanation of symbols

1 is a rotor core, 2 is a motor shaft, 3 is a bearing, 4 is a bearing, 5 is a housing, 6 is an upper housing, 7 is an elastic shaft, 8 is a crown, 9 is a rigid shaft, 10 is a bearing, 11 is a stator core, 12 is Crown Pin, 13 Rotor Pin, 14 High Speed Angle Rotor, 15 Low Speed Swing Rotor, 16 Sample, 17 Drive Device, 26 Intrusion Path, 31 Upper Housing, 34 Rigid Shaft, 38 Bearing, 41 Drive An apparatus, 43 is a crown, 44 is a rotor, 45 is a sample, 46 is a shaft case, and 51 is a labyrinth part.

Claims (3)

A rotor, a driving device, a first rotating shaft that couples the rotor and the driving device to transmit rotational torque, and a space through which the first rotating shaft can be inserted, and is engaged with the rotor In a centrifuge with a possible second axis of rotation,
A bearing having one of an inner ring and an outer ring engaged with the second rotating shaft and the other of the inner ring and the outer ring engaged with the housing is provided to be rotatable between the inner ring and the outer ring. A centrifuge comprising a ball and a shield extending over the inner ring and the outer ring disposed above the ball. The centrifuge according to claim 1, wherein when there are a plurality of bearings supporting the second rotating shaft, a bearing in which the shield is disposed only on the bearing provided on the upper side is used. A rotor, a driving device, a first rotating shaft that couples the rotor and the driving device to transmit rotational torque, and a space through which the first rotating shaft can be inserted, and is engaged with the rotor A second rotating shaft capable of engaging one of the inner ring and the outer ring with the second rotating shaft and the other of the inner ring and the outer ring with the housing, and between the inner ring and the outer ring. A centrifuge having a bearing provided with a ball that enables both of them to rotate, wherein the bearing is a bearing made of a non-magnetic material.

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