JP2018069177A - Centrifugal machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugal machine of a cheap price and a low back type of which vibration during operation is suppressed.SOLUTION: A high rigidity shaft 11 is provided with a first pore which is a pore dug dowm along a central axis 10A from a top face thereof. A fitting member 13 is provided on a bottom side of the first pore. Further, the fitting member 13 is provided with a second pore 13A which is a pore dug down along the central axis 10A from an upper side thereof. In the state that the fitting member 13 is fitted in the first pore, an elastic shaft 12 is fitted in the second pore 13A from an upper side, and consequently, the fitting member 13 and the elastic shaft 12 can be integrated and fixed. In this state, the fitting member 13 can be fitted into the first pore in the high rigidity shaft 11 from an upper side.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a structure of a centrifuge (centrifuge) that separates a sample by rotating a rotor in which the sample is accommodated at high speed.

  A centrifuge is used to separate a sample (for example, culture solution, blood, etc.) for each substance having different density by centrifugal force during high-speed rotation, or to purify and analyze the sample. In a centrifuge, a rotor for mounting a plurality of sample containers into which samples are injected is mounted on a rotating shaft and rotates at a high speed of, for example, about 20000 rpm at the maximum. For this reason, during operation, a configuration is required in which a rotating shaft that rotates at high speed is stably supported by a bearing.

  At this time, when the weight distribution around the central axis of the rotating shaft is symmetrical and the rotating portion, for example, the center of gravity of the entire rotor is on the central axis, vibration during rotation does not occur. However, in reality, the center of gravity does not necessarily coincide with the center axis due to the state of the sample in the rotor, for example, the balance of the sample volume injected into each sample container. Vibration occurs due to the displacement. When the amplitude of this vibration increases, a large load is applied to the rotating shaft itself and the bearing that supports it, and the durability of the rotating shaft may be impaired. Therefore, measures to prevent this vibration amplitude from increasing are required. The Here, in general, in a single centrifuge, a plurality of types of rotors are selected and used, and the amount (weight) of the sample to be accommodated varies depending on the contents of the processing. Varies depending on the type of rotor, the amount of sample, the rotational speed, and the like.

  As described in Patent Document 1, the amplitude of such vibration becomes particularly large due to resonance near the natural frequency of the rotating shaft. Therefore, the rotational speed (the number of rotations per unit time) and the natural frequency of the rotating shaft are A very different situation is preferred. For this reason, for example, when rotating a light rotor at a high speed, it is preferable to use a rotating shaft with a low natural frequency, and when rotating a heavy rotor at a relatively low speed, a rotating shaft with a high natural frequency should be used. preferable. Here, the natural frequency is determined by the shape and size of the rotating shaft and the elastic coefficient. Generally, when the rotating shaft is easily elastically deformed, the natural frequency is low, and when the rotating shaft is difficult to elastically deform and has high rigidity, the natural frequency is low. Becomes higher. For this reason, ideally, it is desirable to select the rotation axis according to the situation, but if the rotation axis is replaced for each process, the burden on the operator will increase, so it will be suitable for most of the assumed cases. It is preferable to use a rotatable shaft.

  In order to deal with a single rotation axis in such various cases, Patent Document 2 describes an axis having high rigidity and high natural frequency (high rigidity axis) and an axis having low rigidity and low natural frequency (high rigidity axis). It is described that a rotating shaft combined with an elastic shaft is used. In this case, the motor that rotationally drives the rotating shaft extending in the vertical direction is positioned below, and the rotor mounted on the rotating shaft is positioned above. The rotary shaft is combined so that the high-rigidity shaft is located below (motor side) and the elastic shaft is located above (rotor side), and the lower high-rigidity shaft is supported by a bearing. Since the elastic shaft is fixed to the high-rigidity shaft at the lower end side and is not directly supported by the bearing, the elastic shaft can be vibrated with a small amplitude with respect to the high-rigidity shaft. Here, since the high-rigidity shaft and the elastic shaft have different characteristics as described above, they are made of different materials, and after each is individually manufactured, they are coaxially coupled to manufacture a rotating shaft. Is done.

JP 2004-64945 A JP 2005-58919 A

  When a rotary shaft is configured by combining a high-rigidity shaft and an elastic shaft as described above, a sufficient area for elastic deformation of the elastic shaft is secured on the upper side, while the high-rigidity shaft is supported by a bearing and is subjected to vibration and deformation. It is necessary to secure a sufficient area on the lower side where the above is suppressed. That is, in the vertical direction, it is necessary to secure these two regions having different characteristics sufficiently wide.

  On the other hand, in particular, a desktop centrifuge is required to have a low overall height, that is, to have a low profile. For this purpose, it is required to shorten the overall length of the rotating shaft. For this reason, it has been difficult to secure the two regions as described above sufficiently wide to achieve desired characteristics. Alternatively, in order to sufficiently secure two regions having different characteristics in the vertical direction as described above, the structure of the rotating shaft (high-rigidity shaft, elastic shaft) becomes complicated, its manufacturing cost increases, and its manufacturing The process has also become complicated. This increased the manufacturing cost of the centrifuge itself.

  For this reason, an inexpensive low-profile centrifuge in which vibration during operation is suppressed has been demanded.

  The present invention has been made in view of such problems, and an object thereof is to provide an invention that solves the above problems.

In order to solve the above problems, the present invention has the following configurations.
The centrifuge of the present invention includes a rotating shaft that is driven to rotate downward along the vertical direction, and a rotor that is driven by being attached to the upper side of the rotating shaft and in which a sample is accommodated. The rotary shaft is rotatably supported by a bearing and has a high-rigidity shaft formed with a first hole that is a recess dug down from above along a central axis, and the high-rigidity shaft And an elastic shaft engaged in the extending direction of the high-rigidity shaft and a second hole portion provided along the central axis are formed, and the elastic shaft is inserted into the second hole portion, and And a fitting member attached to the high-rigidity shaft by engaging with the first hole.
In the centrifuge of the present invention, the cross-sectional shape along the vertical direction of the second hole portion is a conical shape extending upward.
In the centrifuge of the present invention, an inner peripheral surface around the central axis of the first hole portion and an outer peripheral surface around the central axis of the fitting member have a cylindrical shape.
In the centrifuge of the present invention, the high-rigidity shaft is rotatably supported by a first bearing provided on the upper side and a second bearing provided on the lower side, and the fitting member includes It is located below the first bearing.
The centrifuge of the present invention is configured so that the first elastic member is in contact with the fitting member from above in a state where the elastic shaft is inserted vertically so that a gap is formed between the elastic shaft and the outer periphery of the elastic shaft. A fastening member mounted from above on the hole is provided.
The centrifuge of the present invention is characterized in that the outer surface of the fastening member and the inner surface of the first hole portion of the high-rigidity shaft are screwed together.
In the centrifuge of the present invention, the fitting member is made of a material having a thermal expansion coefficient larger than that of the high-rigidity shaft.
The centrifuge of the present invention includes a motor that rotationally drives the high-rigidity shaft from the lower side, and the bottom surface of the first hole is positioned above the magnet provided in the motor. To do.
In the centrifuge of the present invention, the high-rigidity shaft is made of a soft magnetic material.

  Since the present invention is configured as described above, an inexpensive low-profile centrifuge in which vibration during operation is suppressed can be obtained.

It is sectional drawing which shows the structure of the centrifuge which concerns on embodiment of this invention. It is sectional drawing which expands and shows the motor and rotating shaft in the centrifuge which concerns on embodiment of this invention. It is sectional drawing which expands and shows the structure of the rotating shaft in the centrifuge which concerns on embodiment of this invention. It is an assembly figure of the rotating shaft in the centrifuge which concerns on embodiment of this invention. It is sectional drawing which expands and shows the motor and rotating shaft in two examples of the conventional centrifuge.

  A centrifuge according to an embodiment of the present invention will be described. Similar to the centrifuge described in Patent Document 2, the rotating shaft used in the centrifuge is configured by combining a highly rigid shaft and an elastic shaft. FIG. 1 is a vertical sectional view along the axis of the rotating shaft 10 showing the configuration of the centrifuge 100.

  In FIG. 1, the rotor 20 is provided in a rotor chamber 21 </ b> A surrounded by a bowl 21 and is detachably mounted on the upper portion of the rotary shaft 10. In a state where the upper side of the rotor chamber 21 </ b> A is sealed by the lid portion 22, the rotary shaft 10 and the rotor 20 are rotationally driven by a motor 30 provided on the lower side of the rotary shaft 10. The motor 30 and the bowl 21 are fixed with respect to the housing 23.

  Inside the rotor 20, sample containers (not shown) into which a sample to be centrifuged is injected are arranged concentrically. Further, there are a plurality of types (sizes and structures) of the rotor 20, and the user selects these types according to the processing content. The attachment structure of the rotor 20 to the upper part of the rotating shaft 10 is the same as that conventionally known. Actually, a mechanism for controlling the rotation of the motor 30 and the temperature of the bowl 21 is also provided in the housing 23, but since it is irrelevant to the present invention, its description is omitted in FIG. ing.

  FIG. 2 is a cross-sectional view taken along the central axis 10A of the rotary shaft 10 showing an enlarged configuration of the motor 30 and the rotary shaft 10 in FIG. Here, the rotary shaft 10 includes a large-diameter high-rigidity shaft 11 that is integrated with the rotor 31 of the motor 30 on the lower side, and an elastic shaft 12 that is fixed coaxially with the high-rigidity shaft 11. The high-rigidity shaft 11 is rotatably supported by the upper first bearing (ball bearing) 33A and the lower second bearing 33B in the motor housing 32. In the high-rigidity shaft 11, a balance ring 11 </ b> A for balancing the rotation shaft 10 is provided in a region between the rotor 31 and the first and second bearings 33 </ b> A and 33 </ b> B on the upper and lower sides. . A stator (magnet) 34 is fixed to the motor housing 32 at the same height as the rotor 31 and outside thereof. The rotor 31 is constituted by a permanent magnet, the stator 34 is constituted by an electromagnet, and the current flowing through the stator 34 is controlled to rotate the high-rigidity shaft 11 (rotary shaft 10) to which the rotor 31 is fixed. Can be driven.

  The highly rigid shaft 11 is preferably made of a soft magnetic material and a highly rigid material. Since the high-rigidity shaft 11 is a soft magnetic material, the high-rigidity shaft 11 becomes a magnetic flux path by the magnet 34 in the configuration of FIG. 2, and leakage of the magnetic flux is suppressed and a large torque is generated for the rotor 31. Can do. Further, by increasing the rigidity of the high-rigidity shaft 11, the natural frequency of the high-rigidity shaft 11 can be increased. As a result, the high-rigidity shaft 11 can be easily supported by the first and second bearings 33A and 33B. Specifically, martensitic SUS steel can be used as a material constituting the high-rigidity shaft 11.

  On the other hand, as the material constituting the elastic shaft 12, it is preferable to use a material having a wide elastically deformable region and a large toughness, and specifically, an oil temper wire for a spring can be used. In addition, since the high-rigidity shaft 11 and the elastic shaft 12 are made of different materials as described above, both are molded and manufactured separately.

  FIG. 3 is an enlarged view of the upper portion of the high-rigidity shaft 11 and the lower portion of the elastic shaft 12 in FIG. In the rotary shaft 10, when the elastic shaft 12 is coaxially fixed to the high-rigidity shaft 11, a fitting member 13 and a fastening member 14 are used. For this reason, when the elastic shaft 12 is fixed with respect to the high-rigidity shaft 11, both do not contact directly. FIG. 4 is an assembly diagram of the high-rigidity shaft 11, the fitting member 13, the elastic shaft 12, and the fastening member 14.

  As shown in FIG. 4, the high-rigidity shaft 11 is formed with a first hole portion 11B that is a hole portion dug down from the upper surface along the central axis 10A. The bottom surface 11B1 of the first hole portion 11B is formed to be higher than the rotor 31. The first hole portion 11B is roughly divided into a lower region 11B2 that is a region on the bottom surface 11B1 side and an upper region 11B3 on the upper side in the vertical direction. The inner peripheral surface of the lower region 11B2 has a cylindrical shape with the central axis 10A as an axis, and the inner peripheral surface of the upper region 11B3 has a similar cylindrical shape, but the inner peripheral surface is threaded. ing.

  The fitting member 13 has a cylindrical outer peripheral surface corresponding to the inner peripheral surface of the lower region 11B2 in the first hole 11B, and as shown in FIG. 3, the lower region on the bottom side of the first hole 11B. 11B2. As shown in FIG. 4, the fitting member 13 is formed with a second hole 13 </ b> A that is a hole dug down along the central axis 10 </ b> A from the upper side. In this configuration, the second hole portion 13A is formed so as to penetrate the fitting member 13 in the vertical direction. The cross-sectional shape of the second hole 13A in FIG. 3 is a tapered (conical) shape with the upper side slightly widened, and the taper angle is as small as about 1 °.

  The elastic shaft lower portion 12A, which is a region on the lower side of the elastic shaft 12, has a tapered shape corresponding to the tapered shape of the second hole portion 13A. For this reason, in a state before the fitting member 13 is mounted in the first hole portion 11B, the elastic shaft 12 (elastic shaft lower portion 12A) is fitted into the second hole portion 13A from the upper side to fit the fitting member 13 and the elastic shaft. 12 can be integrated and fixed. Thereafter, in this state, the fitting member 13 can be fitted into the first hole 11 </ b> B of the high-rigidity shaft 11 from above.

  Further, the fastening member 14 is provided with a through hole 14A penetrating in the vertical direction. On the other hand, the lower outer peripheral surface 14B of the fastening member 14 is threaded to be screwed into the first hole portion 11B. For this reason, when the fitting member 13 and the elastic shaft 12 are mounted, the fastening member 14 is inserted from the upper side in the first hole portion 11B with the elastic shaft 12 inserted through the through hole 14A in the vertical direction. The outer peripheral surface 14B is fixed by contacting the inner surface of the first hole portion 11B. For this reason, the fastening member 14 is fixed to the high-rigidity shaft 11 and the fitting member 13. On the other hand, at the time of fixing, a gap is formed between the elastic shaft 12 penetrating the through hole 14A in the vertical direction and the inner peripheral surface of the through hole 14A. For this reason, the elastic shaft 12 can be elastically deformed (vibrated) to a small extent in the region above the fitting member 13. On the other hand, the elastic shaft 12 is fixed to the fitting member 13 or the high-rigidity shaft 11 at the lower side of this region.

  In forming the above configuration, first, the high-rigidity shaft 11, the elastic shaft 12, the fitting member 13, and the fastening member 14 are individually molded and manufactured. Thereafter, with the positional relationship shown in FIG. 4, the lower end of the elastic shaft 12 is connected to the lower end of the fitting member 13 in a state where the fastening member 14 is attached to the elastic shaft with the elastic shaft 12 inserted through the through hole 14 </ b> A from above. The two holes 13A are press-fitted from above and fixed. Thereafter, the fitting member 13 in a state where the elastic shaft 12 is press-fitted is fitted into the first hole portion 11B and fixed. At this time, an adhesive may be used. In this state, the fastening member 14 is tightened from the upper side until it is locked to the fitting member 13, and is screwed into the first hole portion 11B to be fixed, whereby the structure of FIG. 3 can be formed.

  As shown in FIG. 2, the high-rigidity shaft 11 is supported vertically by the first and second bearings 33 </ b> A and 33 </ b> B in the vertical direction, whereby the entire rotation shaft 10 is supported. On the other hand, as shown in FIG. 3, in the state where the first hole 11 </ b> B is formed deeper than the height of the first bearing 33 </ b> A and the fitting member 13 is attached, It can be set as the structure which exists in a location lower than the 1st bearing 33A. Even in such a case, the first hole portion 11B does not adversely affect the support of the high-rigidity shaft 11 by the first bearing 33A. Further, in the vertical direction, the elastic shaft 12 is firmly fixed to the high-rigidity shaft 11 in a region where the fitting member 13 is present.

  On the other hand, as described above, the elastic shaft 12 can vibrate in the region above the fitting member 13 located below the first bearing 33A. Therefore, in the above configuration, the elastic shaft 12 is sufficiently secured on the upper side in a region where the elastic shaft 12 can be elastically deformed, while the high-rigidity shaft 11 is supported by the first and second bearings 33A and 33B and is not vibrated or deformed. Ensuring a sufficiently low area on the lower side can be realized without increasing the overall length of the rotating shaft 10.

  Also, this structure can be manufactured easily and at low cost, as will be described below.

  For example, in the high-rigidity shaft 11, instead of providing the first hole 11 </ b> B, a tapered hole corresponding to the second hole 13 </ b> A is provided, and the fitting member 13 is not used. The elastic shaft 12 may be fixed. FIGS. 5A and 5B are diagrams showing two examples of a structure having such a configuration, corresponding to FIG.

  In FIG. 5A, the fitting member 13 is not used, and the rotating shaft 110 is configured by combining a high-rigidity shaft 111 and an elastic shaft 112. A tapered hole portion 111 </ b> A corresponding to the second hole portion 13 </ b> A is formed in the upper portion of the high rigidity shaft 111. The shape of the elastic shaft 112 is the same as that of the elastic shaft 12, and a tapered elastic shaft lower portion 112A of the elastic shaft 112 can be fixed to the hole 111A from above. In this case, since the elastic shaft 112 can vibrate only in a region above the hole 111A, in order to make this region wide, the elastic shaft 112 is located at a portion above the high-rigidity shaft 111. It is necessary to lengthen. For this reason, the full length of the rotating shaft 110 becomes long.

  On the other hand, FIG. 5B is a structure obtained by improving the structure of FIG. 5A so that the entire length of the rotating shaft is shortened. In the rotating shaft 210 used in this case, the highly rigid shaft 211 has a hole 211A. The hole 211A is formed deeper than the hole 111A and has a tapered region 211A1 which is tapered in the vertical direction and provided on the bottom side, and has a larger diameter than the tapered region 211A1 and is formed in the tapered region 211A1. It is divided into a large diameter region 211A2 provided in the upper part. In this case, the taper region 211A1 corresponds to the hole 111A, and the elastic shaft 212 is fixed in the taper region 211A1 in the same manner as the hole 111A. On the other hand, in the large-diameter region 211A2 above the tapered region 211A1, the inner surface of the hole 211A and the elastic shaft 212 can be brought into a non-contact state, so that the elastic shaft 212 vibrates in the large-diameter region 211A2. It can also vibrate on the upper side. On the other hand, the support by the first and second bearings 33A and 33B for the high-rigidity shaft 211 is performed in the same manner as the structure of FIG. Therefore, a region where the high-rigidity shaft 211 is supported by the first and second bearings 33A and 33B and vibration and deformation are suppressed can be sufficiently secured on the lower side, and at the same time, the elastic shaft 212 can vibrate. In addition, the overall length of the rotating shaft 210 can be made shorter than in the case of FIG. For this reason, the structure of FIG.5 (b) is preferable with respect to the low profile of a centrifuge.

  On the other hand, the high-rigidity shaft 211 used here is formed with a tapered region 211A1 and a large-diameter region 211A2, and therefore has a hole 211A deeper than the hole 111A. Here, the inner surface shape of the large-diameter region 211A2 may be non-contact with the elastic shaft 112, and this shape can be a cylindrical surface shape that can be easily processed. For this reason, high precision is not required in the process of forming only the large diameter region 211A2. On the other hand, since the tapered region 211A1 is formed to fix the elastic shaft 212 coaxially to the high-rigidity shaft 211, high accuracy is required for the processing. Therefore, in the end, high accuracy is required to form the deep hole portion 211A, and particularly high accuracy is required in the processing of the tapered region 211A1, which is the deepest portion thereof. In general, it is not easy to form such a deep hole with high accuracy in a steel material constituting the high-rigidity shaft 211, and it is not possible to manufacture such a high-rigidity shaft 211 at a low cost. Have difficulty. That is, with the structure of FIG. 5B, vibration during rotation can be suppressed and the centrifuge can be reduced in height, but it has been difficult to reduce the cost of the centrifuge.

  On the other hand, in the configuration according to the above-described embodiment, the second hole 13A having a tapered inner surface similar to the hole 111A or the tapered region 211A1 is formed in the fitting member 13. Here, the fitting member 13 has a shorter overall length than the high-rigidity shaft 11 and is a small component. Therefore, the fitting member 13 is easy to process, and the tapered second hole 13A as described above is formed in such a manner. It is also easy to form a small fitting member 13. On the other hand, the first hole 11B is formed for the high-rigidity shaft 11 having a long overall length, but the inner surface shape of the first hole 11B is a cylindrical surface shape that can be easily processed as described above. Can be manufactured at low cost.

  Moreover, in said structure, the fastening member 14 is mainly provided in order to suppress that the fitting member 13 moves to the upper side in the 1st hole 11B. For this reason, the fastening member 14 is tightened so as to come into contact with the fitting member 13 from above by being screwed into the first hole portion 11B in a state where the elastic shaft 12 is inserted through the through hole 14A in a non-contact manner. The shape is not required to have high accuracy. Further, the fastening member 14 is also small as the fitting member 13. For this reason, manufacture of the fastening member 14 is also easy. Furthermore, if the fitting member 13 is firmly fixed so as not to move in the vertical direction in the first hole portion 11B, the fastening member 14 is unnecessary.

  As described above, the materials constituting the high-rigidity shaft 11 and the elastic shaft 12 have characteristics that are individually required for each. On the other hand, as long as the fitting member 13 and the fastening member 14 can be fixed to the high-rigidity shaft 11 together with the elastic shaft 12 as described above, the material constituting the fitting member 13 and the fastening member 14 is not affected. There are few restrictions. For this reason, the material which is easy to process as described above can also be used as these materials. In addition, as the material constituting the fitting member 13, the same material as that of the high-rigidity shaft 11 can be used. Alternatively, by using a material having a thermal expansion coefficient larger than that of the material constituting the high-rigidity shaft 11 as the material constituting the fitting member 13, the temperature between the fitting member 13 and the first hole portion 11 </ b> B is increased during the temperature rise. Bonding becomes stronger. Since there are few restrictions with respect to the material which comprises the fastening member 14, compared with the material which comprises the fitting member 13, the room for material selection is wide.

  For this reason, each said part can be manufactured easily and cheaply, and this centrifuge 100 can be made cheap.

  In addition, the configuration according to the above-described embodiment is preferable also in the operation of the motor 30 from the following viewpoints. In FIG. 2, the magnetic path through which the magnetic flux in the motor 30 passes is, for example, from the left stator 34 through the left rotor 31, via the central high-rigidity shaft 11, and through the right rotor 31. It reaches child 34. At this time, the high-rigidity shaft 11 is made of a soft magnetic material (ferromagnetic material), and the first hole portion 11B is provided above the magnetic path, that is, as shown in FIG. By placing the bottom surface 11B1 of 11B above the magnetic path, the space from the left rotor 31 to the right rotor 31 in FIG. 2 can be filled with a soft magnetic material (ferromagnetic material). . Thereby, torque can be generated in the rotor 31 with high efficiency by using the magnetic field formed by the stator 34.

  Thus, even when the bottom surface 11B1 of the first hole portion 11B is set higher than the rotor 31, the upper first bearing 33A is at a position higher than the rotor 31, as shown in FIG. The bottom surface 11B1 of the first hole portion 11B or the fitting member 13 can be provided at a position lower than the first bearing 33A. Thereby, it is possible to widen a region where the elastic shaft 12 can be elastically deformed while suppressing the entire length of the rotating shaft 10. For this reason, in said centrifuge 100, the vibration at the time of operation | movement is suppressed and it can be set as this centrifuge 100 low profile type.

  In the above configuration, the second hole 13A penetrates the fitting member 13 in the vertical direction. However, as long as the elastic shaft can be fixed to the fitting member, the second hole penetrates the fitting member. do not have to. In addition, the inner surface of the second hole portion 13A and the elastic shaft lower portion 112A are tapered, but these shapes are arbitrary as long as the elastic shaft lower portion can be fixed to the second hole portion.

  In the above configuration, the fixing method of the fitting member with respect to the highly rigid shaft (first hole) is arbitrary. In any case, the region where the elastic shaft vibrates can be widened above the fitting member. Further, the fastening method of the fastening member with respect to the high-rigidity shaft (first hole) is also arbitrary, and the shape thereof is arbitrary as long as the elastic shaft can be vibrated while supporting the fitting member in the same manner as described above. is there.

10, 110, 210 Rotating shaft 10A Center shaft 11, 111 High rigidity shaft 11A Balance ring 11B First hole 11B1 Bottom surface 11B2 Bottom region 11B3 Upper region 12, 112, 212 Elastic shaft 12A, 112A Elastic shaft lower part 13 Fitting member 13A Second hole portion 14 Fastening member 14A Through hole 14B Outer peripheral surface 20 Rotor 21 Bowl 22 Lid portion 23 Housing 21A Rotor chamber 30 Motor 31 Rotor (magnet)
32 Motor housing 33A First bearing 33B Second bearing 34 Stator (magnet)
111A, 211A Hole 211A1 Tapered region 211A2 Large diameter region

Claims (9)

A centrifuge comprising: a rotary shaft that is rotationally driven on the lower side along the vertical direction; and a rotor that is driven by being attached to the upper side of the rotary shaft, and a sample is accommodated therein,
The rotation axis is
A high-rigidity shaft formed with a first hole that is a recess that is supported rotatably by a bearing and is dug down from above along the central axis;
An elastic shaft engaged in the extending direction of the high-rigidity shaft on the upper side of the high-rigidity shaft;
A second hole portion is formed along the central axis, and the elastic shaft is inserted into the second hole portion and engaged with the first hole portion to be fitted to the high-rigidity shaft. A joint member;
A centrifuge characterized by comprising:   The centrifuge according to claim 1, wherein a cross-sectional shape along the vertical direction of the second hole portion is a conical shape extending upward.   The centrifuge according to claim 1 or 2, wherein an inner peripheral surface around the central axis of the first hole and an outer peripheral surface around the central axis of the fitting member have a cylindrical shape. The high-rigidity shaft is rotatably supported by a first bearing provided on the upper side and a second bearing provided on the lower side,
The centrifuge according to any one of claims 1 to 3, wherein the fitting member is located below the first bearing.   With the elastic shaft inserted in the vertical direction so that a gap is formed between the elastic shaft and the outer periphery of the elastic shaft, the elastic member is attached to the first hole portion from above so as to come into contact with the fitting member from above. The centrifuge according to any one of claims 1 to 4, further comprising a fastening member.   The centrifuge according to claim 5, wherein an outer surface of the fastening member and an inner surface of the first hole portion in the high-rigidity shaft are screwed together.   The centrifuge according to any one of claims 1 to 6, wherein the fitting member is made of a material having a thermal expansion coefficient larger than that of the high-rigidity shaft. Comprising a motor that rotationally drives the high-rigidity shaft from below;
The centrifuge according to any one of claims 1 to 7, wherein a bottom surface of the first hole portion is positioned above a magnet provided in the motor.   The centrifuge according to claim 8, wherein the high-rigidity shaft is made of a soft magnetic material.

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