Centrifugal separator

Abstract

Centrifugal separator with a rotor (2) with a sample to be separated; a drive device (11) for rotating the rotor with a drive shaft; a chamber (6) for receiving the rotor with a through opening for the drive shaft; a sealing element (9) above the through-opening of the chamber, the sealing element having a through-opening (9d) for the drive shaft and a substantially flat annular region provided therearound; a cooling device (17a, 17b, 18) for cooling the chamber; a lid (7) for closing an opening of the chamber; a drain opening (13) for discharging liquid from the chamber to the outside; and with a wavy portion (10) on the surface of the annular region of the sealing element for deflecting the liquid flow on the annular region from the inside to the outside by means of the air flow generated in the chamber by the rotation of the rotor.

Description

BACKGROUND

[0001] The present invention relates to a centrifugal separator with a cooling device and in particular to a centrifugal separator in which condensate water that forms during cooling in the rotor chamber is effectively discharged to the outside.

[0002] A centrifugal separator can be used to separate and purify a sample. The sample (incubation fluid or blood, for example), contained in a tube or bottle, is attached to a rotor, which rotates at high speed. The rotor's speed is determined depending on the specific sample being examined. The speeds for the respective product groups range from low speed (a few thousand revolutions) to very high speeds (the highest speed is 150,000 rpm). There are various types of rotors, for example, angle rotors with a tube opening at a fixed angle that can operate at high speeds, tilt rotors in which a basket filled with tubes can swing from a vertical state to a horizontal state as the rotor rotates, and so on.In addition, rotors are available in different sizes, for example rotors for very high speeds that impart high centrifugal acceleration to a small amount of sample, and rotors for low speeds that can accommodate a large amount of sample.

[0003] Depending on the sample, the rotors sometimes need to be kept at a low temperature. When a rotor with a sample rotates at high speed in air, the temperature rises due to frictional heat between the outside of the rotor and the air in the rotor chamber. Therefore, many types of centrifugal separators are equipped with a cooling device to cool the sample and keep it at a certain temperature. In such a centrifugal separator with a cooling device, if the lid is opened after centrifugation and air flows into the rotor chamber from outside, condensation may occur on the side wall of the rotor chamber. As described in Japanese Utility Model Examined Publication No.JP S52-42 445B2, described in JP S51-43 967 U and Japanese Patent Publication JP 2006-346 617 A, as a measure against this, in the centrifugal separator, a drain opening is provided in the bottom of the chamber forming the rotor space, and condensate water that has formed in the rotor space is discharged to the outside through the drain opening through a drain line.

[0004] Based on the Fig. Figure 8 of the drawing describes such a known centrifugal separator. Fig. Fig. 8 is a vertical sectional view of a centrifugal separator 101 in which a chamber 106 forms a rotor space 105 in which a rotor 2 is rotated by a drive device 11. A cooling line 18 is arranged around the chamber 106. The outlet side of the cooling line 18 is connected to a compressor 17a, the outlet side of which is connected via a line to a condenser 17b. The outlet side of the condenser 17b is connected to the cooling line 18 via a throttling mechanism (not shown). The cooling line 18, the compressor 17a, the condenser 17b, the throttling mechanism, and so on constitute a cooling device that cools the chamber 106 when a coolant is passed through the cooling line 18. In this way, by cooling the chamber 106 during centrifugation, a temperature increase on the rotor 2 due to the frictional heat between the outside of the rotor 2 and the air in the rotor chamber 105 is prevented.

[0005] In order for the rotor 2 to remain at the desired low temperature of, for example, 4°C, the chamber 106 must be cooled to almost 0°C. If a lid 7 is then opened in this cooled state immediately after centrifugation has ended, outside air penetrates into the rotor chamber 105, and the water contained in the outside air condenses on the inside and outside of the chamber 106, forming condensate. The resulting condensate runs down along the wall surface of the chamber 106 and collects at the bottom of the chamber 106. If the condensate remains in the rotor chamber 105, the air flow in the rotor chamber 105, which is generated during the rotation of the rotor 2, is impeded by the condensate, and the resistance that the drive device 11 must overcome when driving the rotor 2 increases. The condensate can be stirred up by the air flow in the rotor chamber 105 and penetrate into the sample or a basket 3.

[0006] Therefore, in the centrifugal separator described in Japanese patent publication JP 2006-346 617 A, a drain opening 113 is formed in the bottom of the chamber 106 so that the condensate water formed can flow out through the drain opening 113 via a drain pipe 114 and a drain line 115. The condensate in the rotor chamber 105 is influenced by the air flow generated during the rotation of the rotor 2 and flows spirally toward the center of the drive shaft of the drive device 11. The condensate collects there on the drive shaft of the drive device 11 at the bottom of the chamber 106. Therefore, a raised portion 109a of cylindrical shape is provided at the bottom of the chamber 106, which projects substantially vertically upwards, so that the condensate collects around the raised portion 109a and circulates along the outer circumference of the raised portion 109a in the direction of rotation of the rotor 2 such that it adheres to the raised portion 109a.The raised portion 109a is provided with a rubber seal 109 mounted on the outer periphery of the drive device 11. The drain pipe 114 is connected to the drain opening 113, and the condensate is guided to the drain pipe 114 by the rotation of the rotor 2 at the bottom of the chamber 106 and from there discharged to the outside.

[0007] However, with this structure, when the airflow velocity is very high due to a high rotational speed of the rotor 2 or when there is a large amount of condensate, part of the condensate flowing around the raised portion 109a reaches the flat top surface 109b of the rubber seal 109, which covers the opening at the top end of the raised portion 109a, and spirals along the flat top surface 109b toward the rotation center of the drive device. Once the condensate is on the flat top surface 109b of the rubber seal 109, it is affected by the airflow generated by the rotation of the rotor 2, and it is difficult to discharge the condensate through the drain hole 113 located on the outer periphery of the raised portion 109a.

[0008] While it is possible to make the raised section 109a so high that the condensate does not rise above the raised section 109a even when the airflow velocity is high or the amount of condensate is large, as the raised section 109a becomes higher, the chamber 106 also becomes higher, thus increasing the height of the centrifugal separator 101 and reducing its usability for the user.

[0009] Document JP 2000-084 437 A describes a centrifugal separator in which the discharge opening is provided at the bottom of an annular region around the opening for the drive shaft, this annular region forming part of the bottom of the rotor chamber and being recessed relative to its radially adjacent regions of the chamber bottom both in the inner and outer directions. PRESENTATION OF THE INVENTION

[0010] The present invention has been made in view of the background described, and it is an object of the invention to provide a centrifugal separator in which the condensate remaining in the rotor space is effectively discharged to the outside.

[0011] Another object of the present invention is to provide a centrifugal separator in which the condensate water from the surface of a rubber seal is effectively guided to a drain opening on the outer periphery of a raised portion and discharged to the outside.

[0012] Another object of the present invention is to provide a centrifugal separator in which the discharge of condensate water is more effectively carried out only by improving the shape of a rubber seal, so that the manufacturing cost does not increase.

[0013] These objects are achieved by the central separators defined in the patent claims. The essential features of the invention are set forth below. (1) Centrifugal separator with a rotor with a sample to be separated; a drive device for rotating the rotor with a drive shaft; a chamber for accommodating the rotor with a through opening for the drive shaft; a sealing element over the through-opening of the chamber, the sealing element having a through-opening for the drive shaft and a substantially flat annular region provided therearound; a cooling device for cooling the chamber; a lid for closing an opening of the chamber; a drain opening for draining liquid from the chamber to the outside; and with a wavy portion on the surface of the annular region of the sealing element for deflecting the liquid flow on the annular region from the inside to the outside with the aid of the air flow generated in the chamber by the rotation of the rotor. (2) Centrifugal separator according to (1), where an upwardly projecting raised section is provided at the passage opening of the chamber, the sealing element is attached to the raised section, the sealing element comprises a connecting portion connected to the drive device arranged at the center thereof, an attachment portion attached to the raised portion at the periphery thereof, and an annular region formed between the connecting portion and the attachment portion. (3) Centrifugal separator according to (2), wherein the discharge opening is formed in the raised portion. (4) The centrifugal separator according to (1) to (3), wherein the wavy portion extends from the radially innermost portion of the annular portion to the outer peripheral side of the annular portion. (5) The centrifugal separator according to (4), wherein the wavy portion is formed continuously from the radially innermost portion to the outer peripheral portion. (6) Centrifugal separator according to (5), wherein the wavy section is rotationally symmetrical to the center of rotation of the sealing element. (7) Centrifugal separator according to (5), wherein the wavy portion is formed spirally on the top side of the sealing element. (8) A centrifugal separator according to (6) or (7), wherein the wavy portion for preventing the flow of condensate water consists of a projection or a step portion. (9) Centrifugal separator according to (6) or (7), wherein the wavy section for deflecting the condensate water consists of a groove. (10) Centrifugal separator according to (1) to (9), wherein the sealing element is made of rubber and the underside of the sealing element is flat.

[0014] According to the above aspect (1), in the centrifugal separator having the drain port for discharging condensate from the chamber, the wavy portion for deflecting the flow of condensate is provided on the upper surface of the sealing member, which is arranged above the through-hole of the chamber and on the drive shaft. Thus, it is possible to effectively discharge condensate that has risen above the raised portion and condensate that has formed on the upper surface of the sealing member, utilizing the air currents that spiral along the upper surface of the sealing member toward the rotation center of the drive device.

[0015] According to aspect (2) above, the sealing element has an annular portion, and the wavy portion is formed on the top of the annular portion. Condensate flowing spirally along the top of the sealing element toward the rotation center of the driving device can therefore be guided to the outer peripheral edge of the sealing element, flowing downward along the outer peripheral surface of the raised portion. As a result, it is possible to prevent condensate from constantly swirling on the top of the sealing element and not being discharged to the drain port.

[0016] According to the above aspect (3), the drain port is formed at the raised portion, so that it is possible to effectively discharge to the outside the condensate water flowing downward on the outer peripheral surface of the raised portion.

[0017] According to aspect (4) above, the wavy portion is formed to extend from the radially innermost portion of the annular portion to the outer peripheral side of the annular portion. Condensed water spiraling along the top surface of the sealing element is thus stopped by the protrusion at a small angle and cannot overcome the protrusion. In this way, the flow of the condensed water can be directed in a predetermined direction. Furthermore, the condensed water collides with the airflow swirling in the rotor space at a small angle. The resistance to the airflow is therefore small, and air loss can be reduced.

[0018] According to aspect (5) above, the corrugated portion is continuously formed from the radially innermost portion to the outer peripheral portion. Therefore, it is possible to effectively guide the condensate water to the drain port located on the outer peripheral side.

[0019] According to aspect (6) above, the wavy portion is formed rotationally symmetrically to the rotation center of the sealing element. The condensate flowing spirally along the top of the annular portion to the rotation center of the drive device under the influence of the air flow from the rotating rotor is thus evenly directed to the outer peripheral side.

[0020] According to aspect (7) above, the undulating portion is spirally formed on the upper surface of the sealing member. The condensate flowing spirally along the upper surface of the annular portion toward the rotation center of the drive device under the influence of the air flow from the rotating rotor can thus be effectively directed to the outer peripheral side.

[0021] According to the above aspect (8), the wavy portion for preventing the flow of the condensate water is composed of a projection or a step portion, so that the wavy portion can be easily formed integrally with the sealing member.

[0022] According to the above aspect (9), the wavy portion for deflecting the condensate water consists of a groove, so that a guide means for the condensate water can be formed which exerts only a small influence on the air flow swirling around in the rotor space.

[0023] According to the above aspect (10), the sealing member is made of rubber and can therefore be manufactured from a low-cost material. Since the bottom surface of the sealing member is flat, a heat-insulating member and the like can be easily attached to the bottom surface of the sealing member.

[0024] The above and other objects of the invention and the novel features of the invention will also become apparent from the following description of the invention and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a vertical sectional view showing the overall structure of a centrifugal separator 1 in an embodiment of the invention. Fig. 2 is an enlarged sectional view of the rotor chamber 5 of the Fig. 1 surrounding section. Fig. 3 is a sectional view taken along the line AA in the Fig. 1. Fig. 4 is a sectional view along the line BB in the Fig. 3 and shows the shape of a projection in the embodiment of the invention. Fig. 5 is a sectional view corresponding to the sectional view taken along the line BB in the Fig. 3, and shows the shape of the projection in a modification of the embodiment of the invention. Fig. 6 is a plan view of a rubber seal 39 in a centrifugal separator in a second embodiment of the invention. Fig. Fig. 7 is a plan view of a rubber seal 49 in a centrifugal separator in a third embodiment of the invention. Fig. 8 is a sectional view showing the overall structure of a known centrifugal separator 101. DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0025] With reference to the drawings, exemplary embodiments will now be described. In the drawings, like elements are designated by like reference numerals and will not be described repeatedly. Furthermore, in the description, the vertical direction is the direction shown in the Fig. 1 is specified. First embodiment

[0026] The Fig. 1 is a vertical sectional view of a centrifugal separator 1 in an exemplary embodiment. The centrifugal separator 1 comprises a box-shaped housing body 23 made of sheet metal or plastic with a chamber 6 defining a rotor space 5 in the housing body 23, which is closed with a cover 7. The cover 7 can be folded up and down on a hinge 22 to open and close the chamber 6. A cover gasket 8 made of an elastic material such as rubber is attached to the peripheral edge of the opening at the upper end of the chamber 6. Due to the close contact between the cover 7 and the cover gasket 8, the rotor space 5 can be hermetically sealed. A cooling pipe 18 is wound around the chamber 6 and is connected to a compressor 17a and a condenser 17b. The chamber 6 is cooled by passing a coolant through the cooling pipe 18.A heat-insulating element 19 made of a foamed material or the like is mounted outside the cooling line 18. During centrifugation, the operation of the compressor 17a is controlled by a control device 20, maintaining the interior of the rotor chamber 5 at the desired temperature.

[0027] A circular opening is formed in the bottom of the chamber 6, into which a drive device 11 is inserted. At the opening, a raised portion 16 of cylindrical shape is formed, which projects substantially upright upwards from the bottom surface of the chamber 6. The raised portion 16 is a separate component, made of plastic, for example, and manufactured separately from the chamber 6. The raised portion 16 is fastened to the chamber 6 with screws or other connections. However, the raised portion 16 is not necessarily a separate component, but can also be formed integrally with the chamber 6 by pressing. A rubber seal 9 is attached to the circular peripheral edge of the upper part of the raised portion 16, which covers the upper part of the drive device 11. The rubber seal 9 is made of an elastic material, such as rubber.Since the opening at the upper end of the raised portion 16 is covered by the rubber seal 9, the rotor chamber 5 is hermetically sealed. A through-hole is formed at the central axis in the upper part of the rubber seal 9, through which the drive shaft extends upward from the drive device 11. The heat-insulating member 19 surrounding the chamber 6 is provided with an opening 19a in the center of its bottom, the diameter of which is larger than that of the opening in the chamber 6. The drive device 11 is inserted into the opening 19a.

[0028] In the rotor chamber 5, a rotor 2 for receiving samples to be separated is detachably attached to the drive shaft of the drive device 11. The rotor 2 is rotated at high speed by the drive device 11, which is controlled by the control device 20. The drive device 11 is held to the housing body 23 by a number of damping rubbers 12, which are attached to the housing body 23. A number of baskets 3 are pivotally attached to the rotor 2, into each of which a number of tubes 4 containing the samples can be inserted. Fig. Figure 1 depicts the state when the rotor 2 rotates at high speed. The centrifugal force of the rotation causes the baskets 3 to be deflected horizontally (with a pivot angle of approximately 90 degrees). When the speed of the rotor 2 decreases, the pivot angle of the baskets 3 decreases. When the rotor 2 is stationary, the pivot angle of the baskets 3 becomes zero degrees, and the tubes 4 are arranged vertically.

[0029] A control panel 21 is located on the upper part of the lid 7. It allows the user to enter conditions such as the speed of the rotor 2 and the separation time, and it also displays various information. The control panel 21 consists of a combination of a liquid crystal display with control buttons or a touch-sensitive liquid crystal display.

[0030] At a portion of the raised portion 16 of cylindrical shape at the bottom of the chamber 6, a drain hole 13 is formed, to which a drain pipe 14 is connected. Although the drain hole 13 is arranged at only one location on the outer peripheral surface of the raised portion 16 of the chamber 6, the condensate is effectively drained from the bottom of the chamber 6 through the drain hole 13 into the drain pipe 14. This is because the condensate is circumferentially carried and radially inwardly pushed by the air flow generated by the rotation of the rotor 2. The other end of the drain pipe 14 extends vertically downward in the housing body 23 and is connected to one end of a flexible drain pipe 15. The other end of the drain pipe 15 extends outward on the side or rear at the bottom of the housing body 23.In this way, the condensate water in the centrifugal separator 1 can be drained out of the chamber 6 to the outside.

[0031] The Fig. 2 is an enlarged sectional view of the vicinity of the rotor chamber 5. The rubber seal 9 has a downwardly extending attachment portion 9a that is fitted to the upper end of the opening of the raised portion 16. A through-hole 9d is formed at the center axis of the rubber seal 9, through which the upwardly extending drive shaft of the drive mechanism 11 passes. The through-hole 9d engages with an annular groove 11a provided on the outer periphery of the drive shaft, thereby providing a watertight passage to the drive mechanism 11. The rubber seal 9 is provided with a bellows of a predetermined height below the through-hole 9d. The upper surface 9b of the rubber seal 9 extends from the lower end of the bellows (the radially innermost portion 9c) to the outer peripheral side.The area from the radially innermost portion 9c to the attachment portion 9a located at the radially outermost position is formed in an annular shape as a substantially flat surface portion, and the area from the through-hole 9d to the radially innermost portion 9c serves as a connecting portion between the annular portion and the drive shaft of the drive device 11. In the present embodiment, a wavy portion is formed in the substantially flat annular surface portion, which will be described in more detail below.

[0032] The Fig. 3 is a top sectional view taken along the line AA in the Fig. 1. In the illustration, the rotor 2 rotates counterclockwise when viewed from above, as indicated by the arrow 30. When the rotor 2 rotates, swirling air currents are generated above and below the rotor 2 in the rotor chamber 5, as shown by the dot-dash arrow markings 28, 29 (see Fig. 2). In the vicinity of the rotor 2 and the baskets 3, these air streams flow radially from the inside to the outside due to the centrifugal force caused by the rotation of the rotor 2. These air streams then move along the outer peripheral wall of the chamber 6 along this peripheral wall (side surface) of the chamber 6 away from the rotor 2, i.e. upwards (dotted arrow marking 28 in the Fig. 1) or downwards (dotted arrow marking 29 in the Fig. 1) and flow through the areas outside the rotor 2 and the baskets 3 back to the center of rotation of the rotor 2. At the bottom of the chamber 6, the combination of the direction of rotation of the rotor 2 and the direction of the Fig. 1 are air currents that are directed spirally towards the rotation center 25, as indicated by the dot-dashed arrow markings 31. The rotation center 25 is the rotation center of the rotor 2 and the rotation axis of the drive device 11. The air currents flowing towards the rotation center of the rotor 2 do not flow radially from the outside to the inside in a direction perpendicular to the circumferential direction, but rather as a vortex due to the rotational force of the rotor 2, as indicated by the dot-dashed arrow markings 31. Condensate located at the bottom of the chamber 6 therefore also flows spirally radially inwards, as indicated by the dot-dashed arrow markings 32 in the Fig. 3. Even if it is in the Fig. 3 is not shown, the drain pipe 14 and the drain opening 13 are inclined in the direction in which this flow of condensate is received.

[0033] In the centrifugal separator 1 with this structure, the baskets 3 on the rotor 2 are held in a horizontal position by centrifugal force when the rotor 2 is rotated by the drive device 11 in the rotor chamber 5 of the chamber 6, so that the samples in the tubes 4 located in the baskets 3 are centrifuged. The interior of the rotor chamber 5 is cooled by the cooling device, and the sample is kept at a certain temperature by the rotor 2 rotating in the rotor chamber 5. To keep the sample at a low temperature of, for example, 4°C, it is necessary to cool the chamber 6 to almost 0°C. When the lid 7 is opened after centrifugation, air at room temperature enters the rotor chamber 5, and the water contained in the air condenses on the cooled interior of the chamber 6. As a result, condensate accumulates at the bottom of the chamber 6.

[0034] When the rotor 2 rotates again during the next centrifugation process and condensate is present at the bottom of the chamber 6, the condensate is pressed spirally towards the center of rotation, as shown in the top view by the dashed arrow markings 32, so that the condensate collects around the raised section 16 in a cylindrical shape at the bottom of the chamber 6. Since the air currents at the bottom of the chamber 6 move in the directions indicated by the dash-dotted arrow markings 31, the condensate collecting at the raised section 16 flows around the raised section 16 in the direction of rotation of the rotor 2 and, in a sense, clings to it. The condensate then flows through the drain opening 13 opening in the outer peripheral surface of the raised section 16 into the drain pipe 14 and is discharged to the outside via the drain line 15.

[0035] As indicated by the dotted arrow marking 29 in the Fig. 2, however, air currents arise around the cylindrical raised portion 16 at the bottom of the chamber 6, which air currents are directed upwards towards the upper part of the chamber 6. When the speed of the air flow is high or the amount of condensate is large, part of the condensate may be pushed over the upper edge of the raised portion 16 by the air flow and flow spirally along the upper surface 9b of the rubber seal 9 to the rotation center of the drive device 11. Since the condensate flows along the upper surface 9b of the rubber seal 9 to the rotation center of the drive device 11, there is a fear that the condensate may not reach the drain opening 13 as long as the rotor rotates.

[0036] Therefore, in the present embodiment, as in the Fig. 3, the rubber seal 9 covering the opening at the upper end of the raised portion 16 is provided with a wavy portion having a specific shape, for example, a protrusion 10 that deflects the condensate at the upper surface 9b. The protrusion 10 has a spiral shape extending from the radially innermost portion 9c of the upper surface 9b of the rubber seal 9 to its outer peripheral edge. When the condensate is forced by the airflow in a spiral manner along the upper surface 9b of the rubber seal 9 toward the rotation center of the drive device 11, as shown by the dashed arrow marks 33, 34, and 35, the condensate is stopped by the protrusion 10 before it reaches the radially innermost portion 9c.The condensate is prevented by the projection 10 from flowing toward the rotation center of the drive device 11, as indicated by the dashed arrow marks 33, 34, and 35, and instead flows along the projection 10 due to the airflow, which spirals toward the outer peripheral edge of the rubber seal 9. When the condensate reaches the outer peripheral edge of the rubber seal 9, it flows downward by gravity to the lower part of the raised portion 16. The condensate thus flows around the raised portion 16 again and enters the drain opening 13 and the drain pipe 14, from where it is discharged to the outside.

[0037] The Fig. 4 is a sectional view along the line BB in the Fig. 3. The condensate is prevented by the projection 10 from flowing toward the rotation center of the drive device 11, as indicated by the dashed arrow mark 33, and instead flows along the projection 10, which extends spirally toward the outer peripheral edge of the rubber seal 9, with only the air currents overcoming the projection 10, as indicated by the dot-dash arrow marks 31. The projection 10 preferably has a height such that the condensate is stopped therefrom at an angle that is almost vertical. If the projection 10 has only a small height, the condensate is more likely to overcome the projection 10. On the other hand, if the projection 10 is too high, a larger amount of air is stopped by the projection 10, and air loss increases. Experiments by the inventors have shown that it is sufficient if the height of the projection 10 is about 0.5 mm.In the lateral direction, the projection 10 is preferably of such a length that the projection 10, in a spiral shape, makes one or two turns on the rubber seal 9. Since the projection 10 has a spiral shape, the arrangement of the projection is not concentric with respect to the center of rotation in plan view. This allows the condensate to be effectively drained to the outer circumference. The projection 10, in a spiral shape, can also be of such a length that it does not make a full turn on the rubber seal 9. This also sufficiently achieves the advantages of the invention.

[0038] The cross-sectional shape of the projection 10 is not limited to the Fig. 4 is limited to the form shown, various modifications are possible. For example, as shown in the Fig. As shown in Figure 5, a projection 38 on the side along which the condensate flows may have a substantially vertical surface, and on the opposite side, the surface may be formed at an obtuse angle. In this case, the condensate is retained by the substantially vertical surface and does not overcome the projection 38, as in Figure 5. Fig. 5 by the dashed arrow mark 33, while the air flow passes smoothly over the projection 38 due to the obtuse angle of the surface on the opposite side, as shown in the Fig. 5 shows the dot-dash arrow mark 31. This does not increase air loss. However, if the protrusion 38 is too high, the protrusion 38 will retain more air, and the air loss will increase. The inventors' experiments have shown that if the amount of condensate that overcomes the raised portion 16 and reaches the top of the rubber seal 9 is not very large, the condensate will not overcome the protrusion 38 even if the protrusion 38 is low, and that it is sufficient if the height of the protrusion 38 is about 0.5 mm. However, the height of the protrusion 38 does not always have to be about 0.5 mm, but can be appropriately selected depending on the amount and direction of airflow generated in the rotor space and the shape of the protrusion 38.

[0039] As described, in the centrifugal separator 1 of this embodiment, it is possible to guide condensate that overcomes the raised portion 16 and condensate that forms on the upper surface of the rubber seal 9 covering the opening at the upper end of the raised portion 16 and flows along the upper surface 9b of the rubber seal 9 to the underside of the raised portion 16 by means of the projections 10 and 38, respectively. The condensate can thus flow out through the drain port 13 formed in the outer peripheral surface of the raised portion 16 and be discharged to the outside through the drain pipe 14 and the drain line 15. Thus, there is no longer a risk of the sample being mixed with condensate.

[0040] In the present embodiment, a member in the form of a wavy portion, such as the protrusion 10 or 38, is provided to deflect the condensate. However, the deflector is not limited to a protrusion, but may also be formed as a step or a separate member in the form of a profile attached to the top of the rubber seal 9. The wavy portion may also simply be formed as a groove. In the case of a groove, the depth of the groove and the angle of the groove in the circumferential direction are best adjusted so that the condensate flows with the airflow in the groove to the outer peripheral portion. Second embodiment

[0041] With reference to the Fig. 6, the shape of the upper surface of the rubber seal 39 in a second embodiment is described. In the second embodiment, two projections 40 are formed as the wavy portion on the upper surface 39b of the rubber seal 39, which covers the opening at the upper end of the raised portion 16. The projections 40 extend straight at a predetermined angle θ to the circumferential direction from the radially innermost portion 39c on the upper surface of the rubber seal 39 to its outer peripheral edge 39a. The predetermined angle θ is greater than 0 degrees and less than 90 degrees, and preferably lies in the range of 0 to 60 degrees. Due to the rotation of the rotor 2 and the centrifugal force, the air flows indicated by the dot-dash arrow marks 41 are generated, and the condensate accordingly flows spirally along the upper surface 39b of the rubber seal 39 toward the rotation center, as indicated by the dotted arrow marks 42.The condensate impinges on the protrusions 40 before reaching the radially innermost portion 39c and is influenced by the air currents to flow along the protrusions 40 to the outer peripheral side, as indicated by the dashed arrow marks 43. When the condensate reaches the outer peripheral edge of the rubber seal 39, it falls by gravity to the lower part of the raised portion 16. The condensate then flows around the raised portion 16 again and into the drain opening 13 and the drain pipe 14, and is discharged to the outside through the drain line 15.

[0042] Condensed water reaching the radially innermost portion 39c before hitting the projections 40 flows along the radially innermost portion 39c under the influence of the air flow flowing in the axial direction during rotation, as indicated by the dashed arrow mark 44, until it hits one of the projections 40 and mixes with the condensed water flowing toward the outer periphery, as indicated by the dashed arrow mark 43.

[0043] The rubber seal 39 is provided with two projections 40 in the second embodiment, but the invention is not limited to two projections; one projection 40 may be provided, or a plurality of projections 40 may be provided. The angle θ is approximately 45 degrees in the second embodiment, but this angle can also be appropriately adjusted depending on the direction and strength of the airflow generated by the rotation of the rotor 2 and the centrifugal force. In the present second embodiment, the projection 40 is formed in a straight line, but it may also be formed in the shape of a smooth curve or be provided so that the angle to the circumferential direction changes with the distance from the outer circumference. Third embodiment

[0044] With reference to the Fig.7, the shape of the upper surface of the rubber seal 49 in a third embodiment of the invention is described. In the third embodiment, two types of projections 50a, 50b are formed as the wavy portion on the upper surface 49b of the rubber seal 49, which covers the opening at the upper end of the raised portion 16. The projections 50a, 50b extend straight in the direction from the radially innermost portion 49c on the upper surface of the rubber seal 49 to the outer peripheral edge thereof in a direction perpendicular to the circumferential direction and are arranged rotationally symmetrically so that an overlap is present after every 180 degrees of rotation. In the present embodiment, the rotational symmetry is thus twice present.The rotation of the rotor 2 and the centrifugal force generate the air currents indicated by the dot-dash arrows 51, and the condensate flows accordingly along the upper surface 49b of the rubber seal 49 toward the center of rotation, as indicated by the dot-dash arrows 52. The condensate encounters the projections 50a, 50b before reaching the radially innermost portion 49c. The condensate is thus prevented from flowing toward the center of rotation by the projections 50a, 50b and is influenced by the air currents to flow along the projections 50a, 50b toward the outer peripheral edge of the rubber seal 49, as indicated by the dot-dash arrows 51. Once the condensate reaches the outer peripheral edge of the rubber seal 49, it falls by gravity to the lower part of the raised portion 16.The condensate water flows again around the raised section 16 and into the drain opening 13 and the drain pipe 14 and is discharged to the outside through the drain line 15.

[0045] The rubber seal 49 of the third embodiment has a shape such that the projections 50a contact the radially innermost portion 49c, but not the radially outermost portion 49a. On the other hand, the projections 50b do not contact the radially innermost portion 49c, but contact the radially outermost portion 49a. Because the two pairs of projections 50a, 50b have slightly different shapes, the rubber seal 49 is more flexible when fitted onto the raised portion 16, facilitating fitting. Since the elasticity of the rubber seal 49 can decrease, vibration resistance and durability are increased. Due to the simple structure and arrangement of the projections 50a, 50b, the rubber seal 49 of the third embodiment can be easily manufactured, thus improving the condensate drainage effect at a low production cost.

[0046] In the third embodiment, the rotational symmetry of the projections 50a, 50b is not necessarily twofold, but can also be n-fold (with n > 2). Also, the projections 50a, 50b can have the same shape, i.e., be designed to contact both the radially innermost portion 49c and the radially outermost portion 49a.

[0047] The invention has been described with reference to the above embodiments, but is not limited to these embodiments, but can be modified in various ways. For example, in the embodiments, a swing-type rotor 2 was described, but the invention can also be applied to angle rotors in which a tube holder has a fixed angle. As a member for covering the through hole in the chamber and the drive shaft, the rubber seal can also be made of a material other than rubber, possibly even of metal. The wavy portion on the top of the rubber seal can be replaced by a number of small protrusions in a semicircular shape.

Claims

[1] Centrifugal separator with a rotor (2) with a sample to be separated; a drive device (11) for rotating the rotor with a drive shaft; a chamber (6) for receiving the rotor with a through opening for the drive shaft; a sealing element (9) above the through-opening of the chamber, the sealing element having a through-opening (9d) for the drive shaft and a substantially flat annular region provided therearound; a cooling device (17a, 17b, 18) for cooling the chamber; a lid (7) for closing an opening of the chamber; a drain opening (13) for discharging liquid from the chamber to the outside; and with a wavy portion (10) on the surface of the annular region of the sealing element for deflecting the liquid flow on the annular region from the inside to the outside by means of the air flow generated in the chamber by the rotation of the rotor. [2] Centrifugal separator according to claim 1, wherein an upwardly projecting raised portion (16) is provided at the passage opening of the chamber, the sealing element (9) is attached to the raised section, the sealing element has a connecting portion (9c) connected to the drive device (11) arranged in the center thereof, an attachment portion (9a) attached to the circumference of the raised portion, and the annular region which is formed between the connecting portion and the attachment portion. [3] Centrifugal separator according to claim 2, wherein the discharge opening (13) is formed in the raised portion (16). [4] Centrifugal separator according to claim 1, wherein the wavy portion (10) extends from the radially innermost portion of the annular region to the outer peripheral side of the annular region. [5] Centrifugal separator according to claim 4, wherein the wavy portion (10) is formed continuously from the radially innermost portion to the outer peripheral portion. [6] Centrifugal separator according to claim 5, wherein the wavy portion (10) is rotationally symmetrical to the center of rotation of the sealing element (9). [7] Centrifugal separator according to claim 5, wherein the wavy portion (10) is formed spirally on the upper side (9b) of the sealing element (9). [8] Centrifugal separator according to claim 6 or 7, wherein the wavy portion (10) for stopping the flow of condensate water consists of a projection (38) and a step portion. [9] Centrifugal separator according to claim 6 or 7, wherein the wavy portion (10) for deflecting the condensate water consists of a groove. [10] Centrifugal separator according to claim 1, wherein the sealing element (9) is made of rubber and the underside of the sealing element is flat. [11] Centrifugal separator with a rotor (2) with a sample to be separated; a drive device (11) for rotating the rotor with a drive shaft; a chamber (6) for receiving the rotor with a through opening for the drive shaft; a sealing element (9) above the through-opening of the chamber, the sealing element having a through-opening (9d) for the drive shaft and a substantially flat annular region provided therearound; a drain opening (13) for discharging liquid from the chamber to the outside; and with a wavy portion (10) on the surface of the annular region of the sealing element for deflecting the liquid flow on the annular region from the inside to the outside by means of the air flow generated in the chamber by the rotation of the rotor.

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