JP2021181047A - Rotor for centrifugal machine and centrifugal machine - Google Patents

Abstract

To provide a rotor for centrifugal machine capable of correcting imbalance mass of a rotor by moving a ball during high speed rotation.SOLUTION: A balancer 50 housing a plurality of balls 60 are provided on the same axis as a rotary axis line A1 of a swing rotor 30. The balancer 50 adjusts rotational balance of the swing rotor 30 by movements of the balls 60 in a cylindrical part 51. An internal surface 52 of the cylindrical part 51 is formed into a barrel shape, and an area 55 of surface roughness formed rougher than a normal surface is provided for a part including a maximum inner diameter part of a slide surface where the balls 60 slide. The area 55 of surface roughness is arranged intermittently in a circumferential direction, suppresses useless movements of the balls 60 near resonance rotation speed, and effectively suppresses occurrences of self-excited vibration.SELECTED DRAWING: Figure 2

Description

The present invention relates to a centrifuge rotor in which a balancer containing a sphere is provided in a rotating rotor as an unbalanced absorption medium, and a centrifuge using the same.

A centrifuge (centrifuge), which is an example of a rotary machine, is a machine that rotates a rotor containing a sample at high speed to give a high centrifugal acceleration to the sample and separates a high-density sample in the radial direction. If the speed is changed rapidly when accelerating or decelerating the rotation, the sample is agitated and the separated liquid samples are mixed according to the difference in density. To prevent. In addition, since the centrifuge rotates at high speed, it will operate in excess of the resonance rotation speed at which the rotor swings, but the rotor tends to become unbalanced when passing through the resonance rotation speed during acceleration or deceleration. There is a risk that vibration during resonance will increase. Therefore, in order to reduce vibration at the time of resonance, a shock absorbing device such as a damper rubber is provided between the driving unit that drives the rotor and the housing. However, if the rotor is rotated in a state where the unbalance is excessive, only the damper rubber cannot absorb the vibration, and a large noise or vibration may be generated when the rotor resonates. Therefore, there is known a technique of providing a liquid balancer in which a liquid is movably enclosed in an annular case in a rotor, or a ball balancer in which a steel ball is movably stored in the annular case. Patent Document 1 shows an example of providing a ball-type balancer. Here, the principle of the balancer 250 using a ball will be described with reference to FIGS. 11 and 12.

FIG. 11 is a top view seen from the opening of the cylindrical case 251 of the balancer 250 in the direction of the rotation axis A1 (with the upper cover (not shown) removed). The internal space of the balancer 250 has a continuous cylindrical shape between the outer peripheral side wall surface 252 and the inner peripheral side wall surface 254, and a plurality of balls 60 are held so as to be freely movable in the circumferential direction. The outer peripheral side wall surface 252 and the inner peripheral side wall surface 254 are connected by the bottom surface 253 at the lower portion, the bottom surface 253 is a surface on which a plurality of balls 60 are placed, and the balls 60 are placed on the bottom surface 253 when the rotor is stopped. Positioned to touch. In the example of FIG. 11, only two balls 60 are shown, but in reality, the balls 60 are arranged in the cylindrical case 251 so that the rotor is unlikely to be unbalanced, and when the rotor rotates at high speed, all the balls 60 are placed. By moving to the opposite side of the unbalanced mass (not shown), the unbalanced amount is corrected and the vibration of the rotating shaft is suppressed. When the ball 60 is configured to be able to move freely in the circumferential direction as shown in FIG. 11, the ball 60 moves freely when the rotor is started and accelerated, so that the ball moves near the resonance point of the rotor and warps. There was a risk that the vibration would increase. Therefore, by putting a small amount (about 10 cc) of highly viscous oil (for example, ^{about 100 to 3000 mm 2} / S) into the cylindrical case, the ball is made difficult to move and the vibration increase phenomenon is suppressed.

The balancer 250A of FIG. 12 has the same basic shape as the balancer 250 of FIG. 11, but the revolving range of the ball 60 is limited by forming four partition walls 255 in the circumferential direction. Is.

Japanese Unexamined Patent Publication No. 11-262683

Generally, it is known that the vibration increases at the resonance rotation speed (the rotation speed at which the natural frequency of the rotation system including the rotor and the rotation speed of the rotor match), but in addition, the rotation speed is equal to or lower than the resonance rotation speed. In, the position of the center of gravity of the rotating system is located farther from the center of rotation than the center of the rotor, and at a rotation speed higher than the resonance rotation speed, the phase shifts by 180 °. It is known to be located in.

Therefore, when the centrifuge is operated using the above-mentioned conventional ball balancer, it swings in the same direction as the sample unbalance and slowly before reaching the resonance rotation speed at which the rotor vibrates (rotation speed less than the resonance rotation speed). Since it is accelerating, the ball moves in the direction of the unbalanced mass of the sample, and as a result, the ball works to further increase the unbalance. As a result, there is a drawback that the vibration at the time of resonance becomes larger and the noise becomes louder when there is a ball balancer than when there is no ball balancer.

However, when the rotation speed exceeds the resonance rotation speed and reaches a high speed (rotation speed higher than the resonance rotation speed), the rotor swings in the direction opposite to the unbalance of the sample, so that the ball moves in the opposite direction to the unbalance of the sample. Therefore, the balance is automatically adjusted so that the unbalanced mass of the ball becomes small, the vibration of the rotor is sharply reduced, and the effect of the ball balancer can be exhibited.

A ball balancer using the viscosity of oil as shown in FIG. 11 may generate self-excited vibration in the vicinity of the resonance point due to a decrease in the amount of oil due to long-term use. Regular maintenance is required to avoid oil leaks and oil depletion, which increases maintenance costs. Further, in the conventional ball balancer as shown in FIG. 12, since the structure for providing the partition wall is complicated, the manufacturing cost is greatly increased, and the noise when the revolving ball collides with the partition wall is increased. In addition, a structure for sealing the oil inside is required, which has a drawback that the manufacturing cost increases.

The present invention has been made in view of the above background, and an object thereof is to use a rotor for a centrifuge having a balancer capable of correcting an unbalanced mass of the rotating rotor by moving a ball during high-speed rotation of the rotor. To provide a centrifuge.
Another object of the present invention is to provide a centrifuge rotor and a centrifuge using the balancer capable of correcting an unbalanced mass by moving a ball without oil or using a very small amount of oil. It is in.

The following is a description of typical features of the invention disclosed in the present application.
According to one feature of the present invention, a plurality of balls are built in a cylindrical portion centered on a vertical rotation axis, and a sliding surface on which the balls can move is provided between the uppermost portion and the lowermost portion of the cylindrical portion. In a rotor for a centrifuge equipped with a balancer that adjusts the balance by the movement of a ball in a cylindrical portion, a rough surface region (rough surface region) having low smoothness is intermittently provided on the sliding surface. The cylindrical portion has a maximum inner diameter portion between the uppermost portion and the lowermost portion, and the rough surface region is arranged at a position including the maximum inner diameter portion, and the barrel has a whole or a part of the inner surface having the maximum inner diameter portion. Shape Shaped.
rice field.

According to another feature of the present invention, a plurality of rough surface regions are provided intermittently on the circumference including the maximum inner diameter portion. Further, the height of the cylindrical portion in the rotation axis direction should be such that at least a plurality of balls can be arranged in a staggered arrangement of at least two rows in the height direction. Is particularly preferable. The rough surface region may be formed so as to be 10 times or more rougher than a normal sliding surface (smooth surface). For example, the maximum height difference in the normal direction of the surface, that is, the height difference of Peak to Peak is about 100 to 100. It is good to make it about 150 microns.

According to still another feature of the present invention, the cylindrical portion constituting the balancer is provided on an angle rotor having a holding hole for a sample container provided at a predetermined angle with respect to the rotation axis, or on a swing shaft so as to be swingable. It is provided in a swing rotor having a bucket to be mounted. The rough surface region formed in the cylindrical portion can be formed by manufacturing the entire sliding surface as the first rough surface and then roughening the surface by surface treatment. A centrifuge was constructed using the centrifuge rotor thus formed. The centrifuge has a drive unit for rotating the centrifuge rotor, a bowl forming a rotor chamber for accommodating the centrifuge rotor, a door for closing the rotor chamber, and a control unit for controlling the rotation of the drive unit. Consists of including.

According to the present invention, the cylindrical portion of the balancer has a barrel-like shape having a maximum inner diameter portion between the upper end position (ceiling surface) and the lower end position (bottom surface) of the internal space, and is formed on the inner wall surface of the ball. A sliding surface that contacts the outside in the radial direction is provided between the upper part and the lower part of the inner surface of the cylindrical portion, and the sliding surface is provided with a region of a normal surface and a region of a rough surface rougher than the normal surface, so that the revolving motion of the ball is suppressed. As a result, the generation of self-excited vibration can be suppressed and the rotation near the resonance point can be performed smoothly. As a result, it is possible to suppress unnecessary movement of the ball in the vicinity of the resonance rotation speed, and it is possible to enhance the imbalance correction ability. In addition, the structure of the present invention is extremely simple, and the increase in manufacturing cost is small. Furthermore, according to the present invention, excessive vibration of the rotor can be suppressed, and the durability of the centrifuge can be significantly improved.

It is a front view of the centrifuge which concerns on embodiment of this invention, and is the figure which showed the main part by the sectional view. It is a perspective view of the swing rotor 30 of this embodiment (when stopped). It is a perspective view of the swing rotor 30 of FIG. 1 (at the time of high-speed rotation). It is a vertical sectional view of the balancer 50 of FIG. It is a vertical sectional view of the swing rotor 30 of FIG. 2 (when stopped). It is a vertical sectional view of the swing rotor 30 of FIG. 3 (at the time of high-speed rotation). It is a schematic diagram for demonstrating the state of the force applied to the ball 60 inside the balancer 50. It is sectional drawing of the angle rotor 130 which concerns on 2nd Embodiment of this invention. It is a modification of the shape of the sliding surface of the balancers 50 and 150 according to the first and second embodiments of the present invention (No. 1). It is a modification of the shape of the sliding surface of the balancers 50 and 150 according to the first and second embodiments of the present invention (No. 2). It is a figure for demonstrating the principle of the balancer 250 used in the rotor for a conventional centrifuge (the 1). It is a figure for demonstrating the principle of the balancer 250 used in the rotor for a conventional centrifuge (the 2).

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following figures, the same parts are designated by the same reference numerals, and the description of repetition will be omitted. Further, in the present specification, the front-rear, left-right, up-down, inner peripheral side, and outer peripheral side are described as being in the directions shown in the drawing.

FIG. 1 is a vertical cross-sectional view of the centrifuge 1 of the present invention. The centrifuge 1 is provided with a box-shaped housing 11, and is partitioned into two upper and lower spaces by a partition plate 12 in the vicinity of the upper and lower centers inside the housing 11. A substantially cylindrical bowl 4 having an open upper surface is housed in the upper space of the partition plate 12, and a cylindrical protective wall 6 is arranged on the entire outer peripheral side of the bowl 4. The upper surface of the bowl 4 is sealed by an openable door 14, which forms the rotor chamber 3. The door 14 is of an oscillating type pivotally supported by a hinge (not shown) provided on the rear side or the side surface side of the housing, and the front side of the door 14 opens. A refrigerating pipe 17 is wound around the bowl 4, and a cooling device (not shown) keeps the inside of the rotor chamber 3 at a desired temperature. A swing rotor 30 is housed in the rotor chamber 3 as a rotor for a centrifuge. The swing rotor 30 is composed of a rotor body 31 mounted on a drive shaft 8, a plurality of buckets 40 swingably held with respect to the rotor body 31, and a balancer 50 mounted coaxially with the rotor body 31. .. Since the swing rotor 30 can be attached to and detached from the drive shaft 8, another swing rotor, an angle rotor, or the like can be attached to the drive shaft 8 depending on the amount and type of the sample to be centrifuged. A metal accommodating cover that accommodates the entire swing rotor 30 and rotates together with the swing rotor 30 may be used.

An operation display unit 16 is provided on the inclined panel 15 on the upper rear side of the housing 11. The operation display unit 16 functions as an input unit for receiving input from the user and a display unit for displaying information to the user, and can be formed by a plurality of buttons and an LED display device. If a touch-type liquid crystal display is used, the input unit and the display unit can be integrated. The centrifuge 1 is used to centrifuge such as displaying information on the operation display unit 16 and controlling the reception of operation input from the user, controlling the rotation of the motor 7, and controlling a cooling device (not shown) for flowing the refrigerant through the refrigerating pipe 17. A control unit 20 that controls the entire machine 1 is provided. The control unit is an electronic circuit including a microcomputer, volatile and non-volatile storage memories, and the like.

A motor 7 as a drive unit is provided in the lower stage partitioned by the partition plate 12 in the housing 11. The motor 7 is housed inside the motor housing 9, and the motor housing 9 is fixed to the frame 13 via the damper rubber 10. In a rotating machine such as a centrifuge 1, there is a resonance rotation speed at which the swing rotor 30 vibrates, and the resonance rotation speed is determined by the mass and moment of inertia of the motor 7 and the swing rotor 30, and the spring constant and damping coefficient by the damper rubber 10. The motor 7 is arranged so that its drive shaft (rotary shaft) 8 extends in the vertical direction. The drive shaft 8 extends from a through hole 4a formed in the bottom of the bowl 4 so as to reach the internal space of the rotor chamber 3. A shaft cover 5 is fitted between the through hole 4a and the drive shaft 8. By covering the upper part of the motor 7 with the shaft cover 5 in this way, the airtightness of the rotor chamber 3 is maintained, and the cold air in the rotor chamber 3 is prevented from flowing out to the outside of the rotor chamber 3. Further, the drive shaft 8 is provided with a pin (not shown), and the pin engages with the notch 32a provided in the hub 32 of the swing rotor 30, thereby restricting the downward movement. Further, a nut 18 is attached to a female screw portion (not shown) provided at the tip of the drive shaft 8 to fix the swing rotor 30 to the drive shaft 8.

As the swing rotor 30 rotates at high speed, the bucket 40 swings around a swing shaft (swing shaft 37 described later in FIG. 2) due to centrifugal force. When the swing rotor 30 is stopped, the bottom surface of the bucket 40 is positioned to face downward and the opening is positioned to face upward. The swing rotor 30 can be removed from the rotor chamber 3 to the outside with the bucket 40 attached in this way, and only the bucket 40 can be removed from the swing rotor 30 with the swing rotor 30 set in the centrifuge 1. It can be taken out from the rotor chamber 3 to the outside.

The centrifuge 1 operates beyond the resonance rotation speed from the time when it is stopped to the rotation speed at which centrifugation is performed. The resonance rotation speed varies depending on the type of the centrifuge rotor to be mounted and the weight of the sample set in the centrifuge rotor, but is, for example, in the range of 1200 to 1600 rpm. If the rotor for the centrifuge reaches the resonance rotation speed during acceleration, the vibration may increase due to the occurrence of the resonance phenomenon. Therefore, it is important to optimize the damping coefficient of the damper rubber 10 in order to suppress the vibration at that time. However, in the centrifuge 1 of the present embodiment, a balancer 50 is provided in the centrifuge rotor (swing rotor 30) in order to further suppress the vibration at the resonance rotation speed. Further, the operation can be performed even if the error of the balance of the sample set in the rotor is made larger than before.

The balancer 50 is provided on the upper portion of the rotor body 31 so as to be coaxial with the drive shaft 8. The balancer 50 is provided to balance the rotation of the swing rotor 30 during high-speed rotation with higher accuracy, and has a plurality of balls 60 movably built in the cylindrical case 51. Steel balls are used as the balls 60, and the balls 60 are accommodated so that imbalance is unlikely to occur in the rotor when arranged in the circumferential direction. The ball material may be made of ceramics or the like, and in order to improve the unbalance performance in a limited space, it is desirable to use a material having a relatively heavy specific gravity. Further, when the swing rotor 30 rotates at high speed as shown in FIG. 3, the ball 60 in the balancer 50 moves to the opposite side of the unbalanced mass to correct the unbalanced amount and suppress the vibration of the drive shaft 8. FIG. 1 illustrates a state in which the balls 60 are lined up in a row in the circumferential direction, but when the rotation further increases from the state of FIG. 1, when the specific bucket 40A has an imbalance as shown in FIG. , The balls 60 are arranged in a staggered arrangement on the opposite side of the unbalanced mass.

FIG. 2 is a perspective view of the swing rotor 30 when stopped. The cylindrical case 51 shows a state of being attached to the rotor body 31 (= a state during the centrifugal separation operation), while the cover 56 shows a state of being removed (= a state in which the centrifugal separation operation cannot be performed). The swing rotor 30 is composed of a plurality of buckets 40, a rotor body 31 for holding the buckets 40, and a balancer 50 attached to the upper part of the rotor body 31. The swing rotor 30 rotates in a space surrounded by the rotor chamber 3 and the door 14, opens the door 14 when the swing rotor 30 is stopped, and takes in and out the separated sample from the bucket 40. The rotor body 31 includes a hub 32 having a substantially rectangular parallelepiped outer diameter in which a through hole 33 (see FIG. 1) is formed, and an arm portion 34 that is radially outside the hub 32 and extends in all directions in a cross shape when viewed from above. , Horizontal for improving the strength by connecting the branch arm portion 35 connected so as to spread in a V shape from the vicinity of each tip of the arm portion 34 and the adjacent branch arm portion 35 with a planar member. It is composed of ribs 36. The branch arm portion 35 branches into two so as to have an angle of approximately 90 degrees (branch angle). The rotor body 31 is integrally manufactured mainly by precision casting made of stainless cast steel or aluminum alloy, and only the parts requiring combination accuracy are machined or parts are added.

The hub 32 is a place to be installed on the drive shaft 8 (FIG. 1), and when the number of buckets 40 to be attached is 4, the rotation angle is 90 ° around the hub 32 with the rotation axis (rotation center) A1 as the center. The four arm portions 34 are arranged at. The number of arm portions 34 and the holding angle of each branch arm portion 35 are set according to the number of buckets 40 attached, but the arm portion 34 and the branch arm portion 35 have through holes 33 (see FIG. 1). It is arranged so as to be rotationally symmetric with respect to the relative.

The branch arm portion 35 extends in a direction perpendicular to the rotation axis and has a positional relationship parallel to each other with the branch arm portion 35 facing the bucket 40. One bucket 40 is held by using two branch arm portions 35. Each branch arm portion 35 is provided with a through hole (not shown) for attaching a swing shaft 37 having a substantially columnar shape in order to support the bucket 40, and the swing shaft 37 is provided in the through hole. A circlip 43 for preventing disconnection is attached to a swing shaft 37 that is inserted from the side where the bucket 40 is set and protrudes toward the horizontal rib 36 so that the swing shaft 37 does not come off from the branch arm portion 35. The swing shaft 37 is a portion that penetrates the branch arm portion 35 in the horizontal direction and projects convexly with respect to the bucket 40 side and the opposite bucket side. The extending direction of the swinging shaft 37, that is, the axial direction of the swinging shaft 37 is the same as the tangential direction of the rotation locus of the rotor body 31, and is related to the concave recess (not visible in the figure) formed in the bucket 40. By fitting, the bucket 40 is hooked on the rotor body 31.

The bucket 40 has a cup-shaped shape manufactured by integrally molding a metal such as an aluminum alloy, and has a substantially rectangular opening 41 when viewed from above. Near the upper end of the bucket 40, near the periphery of the swing shaft 37, a partially thickened thick portion 42 is formed, and a downward U-shaped depression is formed in the thick portion 42 (not visible in the figure). ) Is formed, the bucket 40 is hooked on the swing shaft 37. During the centrifugation operation, a sample container containing a sample, a cup containing a blood bag, or the like is mounted in the bucket 40, and the swing rotor 30 is rotated at high speed in the mounted state.

The balancer 50 is mounted on the upper side of the hub 32 of the rotor body 31. The balancer 50 is fixed with screws or the like so as to be coaxial with the drive shaft 8. The balancer 50 is composed of a cylindrical case 51, a cover 56 for closing the upper opening 51a of the cylindrical case 51, and a plurality of balls 60. The cylindrical case 51 has a bottom surface 54 and a cylindrical inner wall surface 52, has a circular opening on the upper side, and defines a space for movably storing a plurality of balls 60 in the circumferential direction. The cylindrical case 51 is made of metal and houses 14 balls 60 inside. The ball 60 can revolve and rotate in an unfixed state. When the balancer 50 rotates with the rotation of the swing rotor 30, the ball 60 rotates with the cylindrical case 51, stays in the same place without rotating with the cylindrical case 51, or makes other movements. However, since the centrifugal force due to the rotation of the swing rotor 30 also acts on the ball 60, the ball 60 moves according to the unbalanced state at the time of rotation of the swing rotor 30. During high-speed rotation of the swing rotor 30, the ball 60 moves to the opposite side of the unbalanced mass to correct the unbalanced amount and suppress the vibration of the drive shaft 8. At this time, since the ball 60 is pressed toward the outer peripheral side by the centrifugal force, the ball 60 is kept in contact with the cylindrical inner wall surface 52 of the cylindrical case 51. At this time, the region of the inner wall surface 52 in contact with the ball 60 is a part of the sliding surface. At extremely low speed rotation such as immediately after the start of rotation of the swing rotor 30, the ball 60 revolves around the rotation axis A1 (see FIG. 1) while rotating or not rotating with the rotation of the cylindrical case 51. ..

When the rotation of the swing rotor 30 rises and exceeds a rotation speed near the resonance (for example, 1200 to 1600 rpm), the ball 60 moves to a position for adjusting the imbalance and stays there stably. In this embodiment, in order to stabilize the movement of the ball 60 and the stationary state at the balance position, a plurality of surfaces of the ball 60 so as to be intermittent in the circumferential direction on a part of the sliding surface (inner wall surface 52) of the ball 60. A coarse region 55 was formed. Normally, the inner wall surface 52 is processed into a smooth surface (smooth surface) in order to facilitate the revolution of the ball 60. The sliding surface is a radial outer contact surface of the inner wall surface 52 with which the revolving ball 60 comes into contact, is continuous in the circumferential direction, and has a predetermined width in the rotation axis A1 direction. While the swing rotor 30 rotates at an extremely low speed, the ball 50 contacts the radial outer sliding surface (inner wall surface 52) and the bottom surface 54, but during acceleration to reach the centrifugation speed, the ball 60 and the cylindrical case 51 The contact state with the bottom surface 54 is eliminated, and the contact is made only with the sliding surface (inner wall surface 52) on the outer side in the radial direction.

A plurality of rough surface regions 55 formed on a part of the inner wall surface 52 are provided at equal intervals in the circumferential direction (rotational direction). The rough surface region 55 is formed by smoothing the entire inner wall surface 52 and then roughening a part of the inner wall surface 52 by surface treatment. As a method of rough processing, it is preferable to use a blast process for creating a friction surface by injecting fine balls or sand. If unevenness can be formed on the surface of a steel material having a smooth surface so as to have frictional resistance, the metal is melted by using a method other than blasting, for example, laser processing or corrosive action by chemicals. Etching processing may be used.

The cover 56 of the cylindrical case 51 is attached to form a substantially annular moving space by closing the ball 60 so as to be retained in the cylindrical case 51, and is made of metal or synthetic resin. .. For example, a metal product manufactured by cutting or the like, or a synthetic resin product manufactured by injection or the like. The cover 56 has an annular portion 56a formed on the outer peripheral surface, a cup portion 56b formed on the inner peripheral side of the annular portion 57, and a plurality of through holes 56d formed on the bottom surface portion 56c of the cup portion 56b. Through a screw (not shown) in 56d, the screw is screwed into the female screw hole (not visible in the figure) of the rotor body 31. A spigot portion 56e is further provided on the bottom surface portion 56c, and the spigot portion 56e is fitted into the inner peripheral surface 58a of the cover mounting portion 58, the cover 56 is positioned with respect to the cylindrical case 51, and the annular portion 56a is provided. The lower side surface and the outer peripheral surface of the cup portion 56b are surfaces facing the ball 60.

FIG. 3 is a perspective view of the swing rotor 30 at the time of high-speed rotation. As in FIG. 2, the cover 56 is shown in a state where the cover 56 is removed so that the internal configuration of the balancer 50 can be understood. When the swing rotor is stationary without rotating, as shown in FIG. 2, the vertical center axis of the bucket 40 and the rotation axis A1 (see FIG. 1) are parallel (swing angle = 0 °). However, as the rotation speed of the swing rotor 30 increases, centrifugal force acts on the bucket installed so that it can swing, the bucket rotates around the swing axis, the swing angle becomes larger than 0 °, and the bucket becomes horizontal. The rotational speed at which the centrifugal force is generated is almost horizontal (swing angle ≈90 °) as shown in FIG. Here, the "swing angle" is a relative angle formed by the central axis B1 of the bucket 40 with the rotation axis A1. After the centrifugal separation operation is completed, the swing rotor 30 is decelerated, the swing angle gradually decreases as the rotation speed decreases, and the swing angle becomes 0 again when the rotation is stopped. In this way, the swing angle of the swing rotor 30 changes depending on the magnitude of the centrifugal force during centrifugation.

When the rotation speed of the swing rotor 30 increases, the ball 60 moves away from the bottom surface 54 of the cylindrical case 51 and moves the inner wall surface 52 formed in a barrel shape toward the maximum inner diameter position in the upward direction, as shown in FIG. It will be lined up in a row at the maximum inner diameter position. Further, when the speed becomes higher than the resonance rotation speed of the swing rotor 30, the center of vibration moves from the center of the cylindrical case 51 to the unbalanced mass side, and as a result, the ball 60 moves horizontally to the opposite side of the unbalanced mass. Occurs. Due to this horizontally moving force and the variation in height of each ball 60, the balls 60 move alternately up and down over the surface rough area 55 of the adjacent balls 60 and the sliding surface, and move in a staggered arrangement or two rows up and down. Gathers on the opposite side of the unbalanced mass. That is, as shown in FIG. 3, the plurality of balls are all concentrated on the side opposite to the unbalanced weight side.

The number of balls gathered is automatically adjusted until the force of returning the vertically displaced balls to a horizontal row generated by the radius of curvature of the barrel shape on the inner surface of the cylinder is balanced. As the swing rotor 30 accelerates, the balls 60 in the cylindrical case 51 separate from the bottom, and the balls 60 gradually rise as the rotation speed increases, but since there is no sudden movement of the balls 60, the balls 60 collide with each other. Sound can also be suppressed. Further, in a state where the balls are lined up in a row at the maximum inner diameter position shown in FIG. 6, abnormal vibration due to the movement of the balls in the circumferential direction, for example, in the range of 1200 to 1600 rpm can be suppressed. Therefore, in this embodiment, it is possible to have a so-called oilless structure in which oil is not put into the internal space where the balls 60 are arranged.

FIG. 4 is a partial vertical sectional view of the balancer 50 alone of FIG. 2, and is a state when the swing rotor 30 is stopped. In this figure, it is a cross section in a state where the cover 56 is removed. Assuming that the radius of the ball 60 is r, the diameter is 2r. The height of the internal space of the cylindrical case 51 is set to be slightly larger than twice the diameter of the balls 60, and is formed so that two balls 60 are lined up in the vertical direction. A convex portion 54a that rises upward is formed on the inner peripheral side of the bottom surface 54 on which the ball 60 is placed, and restricts the movement of the ball 60 to the inner peripheral side. The inner wall surface 52 (52a to 52d) of the cylindrical case 51 of the cylindrical case 51 is formed in a slight barrel shape, and in the vicinity of the arrow 52a, the inner wall surface 52 (52a to 52d) is inclined outward so as to have a slightly larger diameter as it goes upward. An arc surface or an inclined surface is formed. The inner wall surface 52 has a maximum inner diameter near the central portion of the arrow 52b (the central portion of the sliding surface 53), and in the vicinity of the arrow 52c, an arc surface or an inclined surface narrowed down so that the diameter becomes slightly smaller toward the top. It is formed. The area around the arrow 52d has a shape in which the diameter is slightly narrowed toward the top, in order to form a stop portion for mounting the annular portion 56a (see FIG. 2) of the cover 56. The annular portion 56a of the cover 56 (see FIG. 3) abuts on the upper side of the opening 51a. A convex portion 54a is formed on the inner peripheral side of the bottom surface of the cylindrical case 51, and guides the ball 60 to stay on the outer peripheral side of the cylindrical case 51 when the swing rotor 30 is stationary.

The sliding surface 53 is a range of the inner wall surface 52 where the ball 60 can come into contact. Since the radius of the ball 60 is r, the remaining range of the inner wall surface 52 excluding the portion r downward from the upper end position and the portion r upward from the lower end position becomes the sliding surface 53 and abuts on the ball 60. .. It is important that the sliding surface 53 is formed smoothly so as not to interfere with the revolution of the ball 60. On the other hand, in this embodiment, the rough surface region 55 is formed on a part of the sliding surface 53. A total of 10 rough surface regions 55 are formed intermittently in the circumferential direction. Inside the convex portion 54a, a cover mounting portion 58 that comes into contact with the bottom surface of the cup portion 56b of the cover 56 is formed. A through hole 59 is formed in the center of the cover mounting portion 58.

FIG. 5 is a vertical cross-sectional view of the swing rotor 30 of FIG. 2, which is a state when the swing rotor 30 is stopped. Since no centrifugal force is applied to the bucket 40 when the swing rotor 30 is stopped, the opening of the bucket 40 is upward (the center line B1 of the bucket 40 is in the vertical direction) due to the action of gravity. Similarly, since centrifugal force is not applied to the plurality of balls 60, they are placed on the bottom surface 54.

FIG. 6 is a vertical cross-sectional view of the swing rotor 30 of FIG. 3, which is a state when the swing rotor 30 reaches the vicinity of the resonance rotation speed. When the swing rotor 30 starts accelerating and reaches near the resonance rotation speed, the balls 60 move to the vicinity of the maximum inner diameter position of the barrel-shaped inner wall surface 52 by centrifugal force, and rotate in a line in the circumferential direction in the vicinity thereof. do. Further, when the bucket 40 reaches the vicinity of the resonance rotation speed, the bucket 40 also swings so that the center line B1 is in a horizontal state.

FIG. 7 is a schematic diagram for explaining the state of the force applied to the ball 60 inside the balancer 50. When the swing rotor 30 reaches the vicinity of the resonance rotation speed, the balls 60-1 and 60-2 are gathered on the outside of the annular chamber by centrifugal force and are pressed against the inner wall surface 52, and the balls 60-1 and 60-2 are in a state of being pressed against the inner wall surface 52. 60-2 is in a state of revolving (rotation about the rotation axis A1) due to centrifugal force. At this time, if the surface rough regions 55 are formed at a plurality of locations in the circumferential direction, the frictional force acts on the inertial force, so that the movement of the ball 60-1 is suppressed. By providing the rough surface region 55 on the inner wall surface of the cylindrical case 51 in this way, it is possible to suppress the revolution motion of the ball 60-1 near the resonance rotation speed, suppress the generation of abnormal vibration, and centrifuge. It is possible to improve the imbalance with respect to the imbalance. On the other hand, since the ball 60-2 is not on the rough surface region 55, the revolution motion is not suppressed. In FIG. 7, only two balls 60-1 and 60-2 are shown in the circumferential direction, but when a large number of balls 60 are arranged so as to be substantially continuous in the circumferential direction, the rough surface region of the balls 60 is shown. Since a large frictional force acts only on the ball 60-1 sliding on the 55, the revolution of the adjacent ball 60 (for example, the ball 60 (not shown) existing between 60-1 and 60-2) should be suppressed. As a result, the revolution of the entire ball 60 can be suppressed. After that, when the unbalanced amount of the swing rotor 30 is less than the unbalanced absorption limit point by the ball 60 when the centrifugal rotation speed is exceeded and the centrifugal separation rotation speed is reached, the balls 60 are mutually until the vibration amplitude becomes zero. The vibration of the swing rotor 30 can be reduced because the swing rotors 30 approach each other in a staggered arrangement.

Although the embodiment of the present invention has been described above based on the swing rotor 30, any type of rotor may be used, and the so-called angle rotor 130 can be similarly applied. FIG. 8 is a cross-sectional perspective view of the angle rotor 130. The rotor body 131 is an integral structure (solid type) manufactured by machining using an aluminum alloy or a titanium alloy material. The rotor body 131 is provided with six cylindrical holding holes 132 for mounting a sample container (not shown). The holding hole 132 has substantially the same shape as the outer shape of a cylindrical sample container (not shown). By making the holding hole 132 large enough to cover almost the entire sample container, it is possible to prevent deformation of the sample container itself during the centrifugation operation. On the upper side of the rotor body 131, a liquid sealing annular groove 133 is provided to prevent liquid leakage from the rotor body 131 in the unlikely event that a sample leaks from the sample container (not shown) during centrifugation, and an upper portion thereof is provided. The opening 131a is formed in. A rotor cover (not shown) can be attached to the opening 131a. A drive shaft hole 136 for mounting on the drive shaft 8 of the motor 7 is formed below the central shaft of the rotor body 131. It is important that the drive shaft hole 136 is fixed so as to be relatively non-rotatable with respect to the drive shaft 8, and can be mounted by using a fixing method known in the field of centrifuges.

In the vicinity of the center of the rotor body 31, a large hollowed out portion 134 as if hollowed out downward is formed. The hollow portion 134 can reduce the weight of the upper part of the central shaft of the rotor body 131, and is provided to further reduce the weight of the rotor body 131. In this embodiment, the balancer 150 is provided by using the space forming the hollow portion 134. The balancer 150 is composed of a cylindrical chamber 151 formed in the central portion of the rotor body 131, a plurality of balls 160 housed inside the cylindrical chamber 151, and a cover 156 that closes the opening 151a of the cylindrical chamber 151. .. A protrusion 154 protruding upward is formed in the center of the cylindrical chamber 151, and a screw hole 154a for fixing the cover 156 is formed in the upper axial center of the protrusion 154. A screw portion 157 to be screwed with the screw hole 154a is formed on the lower side of the cover 156. The threaded portion 157 extends in the axial direction, and a male threaded portion (not shown) is formed.

Although not shown in FIG. 8, the inner wall surface 152 of the balancer 150 has a barrel shape, and a rough surface region as shown in FIGS. 2 to 4 is formed. The position where the surface rough region is arranged and the manufacturing method may be arranged in the same manner as in the first embodiment. By providing the balancer 150 of this embodiment in the angle rotor 130 in this way, self-excited vibration (revolution vibration of the ball) near the resonance point of the angle rotor can be suppressed. Further, even if an imbalance occurs due to the sample, the balancer 150 can reduce the vibration of the angle rotor 130 during high-speed rotation. In the embodiment of FIG. 8, the balancer 150 is formed by directly forming the cylindrical chamber 151 in the rotor body 131 of the angle rotor 130, but is formed by the cylindrical case 51 and the cover 56 as in the first embodiment. A separate balancer may be configured to be fixed to the inside or the outside of the rotor body 131.

Next, a modified example of the arrangement example of the surface rough region 55 will be described with reference to FIGS. 9 and 10. Here, it is a developed view which developed the inner wall surface 52 of a cylindrical case 51 in a plane shape, and shows 1/3 (120 °) of the whole circumference. Since the inner wall surface 52 is barrel-shaped, it does not have a completely flat shape, but since the degree of curvature of the barrel-shaped shape is extremely small (radius R = about 200 mm), it is similar to a completely developed cylindrical surface. And illustrated.

FIG. 9A is an arrangement example of the rough surface region 55 of the first embodiment. Here, the inner wall surface 52 is configured to have a height of at least 1.41 times the radius r of the ball 60, preferably twice or more. The range from the lower end position (bottom) to the height r (= radius of the ball 60) above and from the upper end position (top) to the height r below is the sliding surface 53 with which the ball 60 can contact. In the present invention, this region becomes a smooth surface. The upper region 52c and the lower region 52a of the sliding surface 53 are formed with the same smoothness as the sliding surface 53. This is because the smoothness is lowered by forming only the surface of a specific region (rough surface region 55) after forming the entire inner wall surface 52 with the same smoothness.

The rough surface region 55 in FIG. 9A has a rectangular shape, and the sliding surface 53 (first rough surface region) remains between the adjacent rough surface regions 55. Therefore, when the ball 60 revolves in the circumferential direction while in contact with the inner wall surface 52, the revolving speed is suppressed by alternately contacting the rough surface region 55 and the sliding surface 53, and the revolving motion of the ball 60. Is suppressed. As described above, the shape of the rough surface region 55 may be not only a quadrangle but also another form as long as the rough surface region 55 and the sliding surface 53 can be alternately contacted. FIG. 9B is a round surface rough surface region 55A. The interval T of the rough surface region 55A is arbitrary and may be narrowed or widened. However, the rough surface region 55A is preferably arranged so as to straddle the maximum inner diameter position when viewed in the vertical direction, but the same effect can be obtained even if the surface rough region 55A is arranged close to each other without straddling the maximum inner diameter position. Further, although the interval T seen in the circumferential direction of the rough surface region 55A is constant, the intervals T are not all constant and may be increased or decreased.

FIG. 9C is a surface rough region 55B having a regular pentagon. Here, too, it is important that the surface rough region 55B straddles the maximum inner diameter position when viewed in the vertical direction, and that the maximum inner diameter position is intermittently arranged in the circumferential direction. By forming the rough surface regions 55A and 55B in this way, the same effect as that of the first embodiment shown in FIGS. 1 to 7 can be obtained.

FIG. 10A is a diamond-shaped rough surface region 55C. The rough surface region 55C is also intermittently arranged at the maximum inner diameter position. Since the plurality of balls 60 are aligned at the same height as the maximum inner diameter position near the resonance rotation speed, the surface rough region 55C and the sliding surface 53 are configured to appear alternately when the maximum inner diameter position is viewed in the circumferential direction. Then, the same effect can be obtained regardless of whether the shape of the rough surface region 55C is a rhombus, a triangle, or another shape.

FIG. 10B shows a variable smoothness of the entire inner wall surface 52. In the figure, black indicates that the dark portion has low smoothness and is a rough surface, and the white portion indicates that the smoothness is high. Here, the smoothness from the lower end of the inner wall surface 52 to the maximum diameter position is gradually coarsened, and the smoothness from the upper end of the inner wall surface 52 to the maximum diameter position is gradually coarsened. Even if the smoothness of the inner wall surface 52 is variable in the vertical direction in this way, resonance does not occur unless the rotational motion of the ball 60 is hindered by the resonance rotational speed and the rotational motion of the ball 60 is impeded by a rotational speed other than the resonance rotational speed. It is possible to suppress the occurrence of abnormal vibration near the rotation speed. The smoothness of the inner wall surface 52 may be varied not only in the vertical direction but also in the circumferential direction, and the effect of the present invention can be obtained if the smoothness on the sliding surface 53 is not the same.

Although the present invention has been described above based on the examples, the present invention is not limited to the above-mentioned examples, and various modifications can be made without departing from the spirit of the present invention.

1 Centrifuge 3 Rotor chamber 4 Bowl 4a Through hole 5 Shaft cover 6 Protective wall 7 Motor 8 Drive shaft 9 Motor housing 10 Damper rubber 11 Housing 12 Partition plate 13 Frame 14 Door 15 Tilt panel 16 Operation display 17 Refrigeration pipe 18 Nut 20 Control part 30 Swing rotor 31 Rotor body 32 Hub 32a Notch part 33 Through hole 34 Arm part 35 Branch arm part 36 Horizontal rib 37 Swing shaft 40 Bucket 40A (Specific) bucket 41 (Bucket) Opening 42 (Bucket) ) Thick part 43 Circlip 50 Balancer 51 Cylindrical case 51a Opening 52 Inner wall surface 53 Sliding surface 54 Bottom surface 54a Convex part 55, 55A to 55C Rough surface area 56 Cover 56a Circular part 56b Cup part 56c Bottom part 56d Through hole 56e Inlay part 57 Circular part 58 Cover mounting part 58a Inner peripheral surface 59 Through hole 60 Ball 130 Angle rotor 131 Rotor body 131a Opening 132 Holding hole 133 Liquid sealing annular groove 134 Hollowed part 136 Drive shaft hole 150 Balancer 151 Cylindrical Room 151a Opening 152 Inner wall surface 154 Protruding part 154a Screw hole 156 Cover 157 Threaded part 160 Ball 250, 250A Balancer 251 Cylindrical case 252 Outer side wall surface 253 Bottom surface 254 Inner peripheral side wall surface 255 Partition A1 (swing rotor) Rotating axis B1 Centerline (of the bucket)

Claims (11)

Multiple balls are built in the cylindrical part centered on the vertical axis of rotation,
It has a sliding surface on which the ball can move between the top and bottom of the cylinder.
In a centrifuge rotor equipped with a balancer that adjusts the balance by the movement of the ball in the cylindrical portion.
A rotor for a centrifuge, characterized in that a region having a rough surface having low smoothness is intermittently provided on the sliding surface. The cylindrical portion has a maximum inner diameter portion between the uppermost portion and the lowermost portion.
The rotor for a centrifuge according to claim 1, wherein the rough surface region is arranged at a position including the maximum inner diameter portion. The rotor for a centrifuge according to claim 2, wherein the entire or part of the inner surface of the cylindrical portion has a barrel shape having the maximum inner diameter portion. The rotor for a centrifuge according to claim 2 or 3, wherein a plurality of rough surface regions are intermittently provided on the circumference including the maximum inner diameter portion. The centrifuge according to claim 4, wherein the height of the cylindrical portion in the rotation axis direction is set so that the plurality of balls can be arranged in a staggered arrangement of at least two rows in the height direction. For rotor. The rotor for a centrifuge according to claim 5, wherein the rough surface region is 10 times or more rougher than a normal surface. The rotor for a centrifuge according to claim 6, wherein the rough surface region has a maximum height difference of about 100 to 150 microns in the normal direction of the surface. The rotor for a centrifuge according to any one of claims 1 to 7, wherein the cylindrical portion is provided in an angle rotor having a holding hole provided at a predetermined angle with respect to the rotating shaft. The invention according to any one of claims 1 to 7, wherein the cylindrical portion is provided on a swing shaft provided at one end of the arm portion and a swing rotor having a bucket provided on the swing shaft so as to be swingable. The described centrifuge rotor. The centrifuge according to any one of claims 1 to 8, wherein the rough surface region is formed by smoothing the entire sliding surface and then roughening the sliding surface. Rotor. The centrifuge rotor according to any one of claims 1 to 10.
A drive unit for rotating the centrifuge rotor, a bowl forming a rotor chamber for accommodating the centrifuge rotor, and a door for closing the rotor chamber.
A centrifuge having a control unit that controls rotation of the drive unit.

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