centrifuge

Abstract

Sufficient attenuation should be achieved over as wide a frequency range as possible. The present invention relates to a centrifuge comprising: a) a rotor (32) for receiving a container having material for the centrifuge; b) a drive shaft (42) on which the rotor (32) is mounted; c) a motor (18) for driving the rotor (32) via the drive shaft (42); and d) a damping element (20a, 22a) including a spring shaft (20e, 22e, 24e; 46e, 48e, 50e; 52e, 54e, 56e; 64e, 66e, 68e). The present invention relates to a centrifuge (10), in particular a laboratory centrifuge, comprising: e) a bearing unit (44) including bearings (20, 22, 24, 46, 48, 50, 52, 54, 56; 64, 66, 68) with bearings (20, 22, 24a; 46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a); and f) a carrier element (16) for fixing a motor (18) via the bearing unit (44) within the centrifuge (10). The present invention is characterized in that at least one damping element is a metal cushion (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) made entirely of metal and including a wire knit having elastic properties.

Description

Technical Field

[0001] The present invention relates to a centrifuge in the form specified in the first part of claim 1, particularly a laboratory centrifuge.

Background Art

[0002] Centrifuges of various designs are known per se. Particularly in the case of laboratory centrifuges, since the space in the laboratory is limited, efforts have been continuously made to propose as compact a device as possible. In addition, since laboratory centrifuges usually have a lot of stacking from above, it is necessary to have sufficient clearance above for opening the lid.

[0003] At the same time, in the design of a centrifuge, it is necessary to consider good damping in order to cancel out the unbalance that inevitably occurs in the centrifuge during operation. For this reason, for example, it is generally known to support a motor equipped with a rotor with a damping element whose spring axis is parallel to the longitudinal axis of the motor. Usually, the damping element is basically made of natural / synthetic rubber. Such a damping element made of natural / synthetic rubber is available at a reasonable price as catalog parts with a wide variety of designs and materials. Their properties are clearly defined and documented, and damping elements of such a design can be used in a wide range of applications. For this reason, these damping elements have been used in the new design or redesign of centrifuges. This type of damping element is also perfectly suitable for applications that prevent a large unbalance from occurring during operation.

[0004] This type of centrifuge design is also used in fully automated systems. For example, the use of a dual rotor requires high unbalance resistance for the centrifuge. For example, when the centrifuge is operated in a state where an odd number of samples are loaded into the rotor, a bucket with a sufficient amount of samples in one rotor and a bucket with no samples in the other rotor.

[0005] However, centrifuges are being used for increasingly complex operations. Known rubber damping elements have proven to be insufficient in terms of damping characteristics and damping range, so the imbalance generated during the centrifugation operation is becoming an ever greater problem for such complex tasks and processes. The damping elements of previous designs are unable to sufficiently absorb the forces generated and are having an adverse effect on the processes being carried out. On the other hand, these damping elements are being stressed in such a way as to shorten their lifespan and that of the centrifuge.

[0006] Therefore, attempts have been made to solve this problem by changing the arrangement of the spring axes of the damping elements with respect to the rotor and the motor. Furthermore, connecting a plurality of different types of damping elements in series has also been done.

[0007] A centrifuge is known, for example, from DE 39 22 744 A1, which comprises a rotor for receiving a container containing the material to be centrifuged. The rotor is driven via a drive shaft, for which purpose the drive shaft is connected to a motor. The motor with the drive shaft and the rotor is connected to a bearing unit having a plurality of damping elements including spring axes. The whole is connected, together with the parts supported by the motor, to a support element for fixing the motor in a predetermined position of the centrifuge. The spring axes of the damping elements may be set at an acute angle δ with respect to the rotation axis Y of the motor. The damping elements are each connected to the bearing unit via a support column. The support columns are set and arranged to be concentric with the respective spring axes of each damping element. The bearing unit includes a support plate. The damping elements are formed in the form of two equalization chambers by a coil spring and another damping element, between which damping fluid flows through a throttle channel according to the direction of the load.

[0008] In WO 2015 / 128296 A1, it is known to set the spring axes of the damping elements obliquely and to use a metal plate spring (referred to in this document as a lug) as a further damping element in combination with a rubber buffer.

[0009] GB 739 666 A discloses a centrifuge in which a rubber cushion is provided as a damping element and an arm that damps via frictional resistance is provided as a further damping element.

[0010] US 1 848 641 A discloses a centrifuge in which a motor is supported within a housing by means of a strut and a spring-shaped damping element.

[0011] DE 195 16 904 A1 discloses a laboratory centrifuge equipped with a rubber vibration damping device.

[0012] Known means of damping a motor with a rotor supported thereon are not very effective, especially in the frequency band from 15 to 50 Hz. However, the aim is both the acceptable unbalance of the centrifuge and the damping over the entire frequency range occurring during operation of the centrifuge, thereby increasing the utilization options of the centrifuge and still guaranteeing the safe operation of the centrifuge. In this case, there must be no breakout of the rotor, especially in the particularly important resonance range. The runout (or displacement) of the rotor must be made as small as possible. The overall size must not increase due to additional means for improving damping.

[0013] At the same time, the vibration transmission from the rotating mass, i.e., an unbalanced rotor during operation that may only be partially loaded, to the support plate with the centrifuge housing connected to the support plate must be kept as low as possible. Otherwise, unacceptable noise will occur. This vibration, for example, causes the centrifuge to start moving on an experimental bench. SUMMARY OF THE INVENTION

[0014] It is an object of the present invention to further improve a centrifuge of the type defined in the preamble of claim 1 such that sufficient damping is achieved over as wide a frequency range as possible while avoiding the above-mentioned drawbacks.

[0015] This object is achieved by the combination of the features of claim 1 and the features of its preamble.

[0016] The dependent claims relate to further advantageous embodiments of the invention.

[0017] The present invention is based on the insight that metal cushions known for applications that withstand harsh use or harsh environmental conditions have significantly better damping characteristics over a wider frequency range than the damping elements previously known for use in centrifuges, and thus can be used as damping elements.

[0018] According to the present invention, at least one damping element is a metal cushion comprising a woven wire mesh having elastic properties, and is entirely formed of metal. However, the individual parameters of the metal cushion for a centrifuge first need to be determined in a complex manner. Diagrams showing the frequency-dependent values for the damping of the metal cushion cannot be obtained from the manufacturer of such metal cushions. Therefore, complex calculations and measurements are required to be able to design a metal cushion for a relatively lightweight centrifuge, especially a laboratory centrifuge. Therefore, all measurements, calculations and simulations for designing the metal cushion of a centrifuge have to be carried out step by step for each individual type of centrifuge. When this is done and the parameters are optimized for the centrifuge, excellent results are obtained in terms of damping characteristics over a wide frequency range.

[0019] In certain mounting situations, it is advantageous for the metal cushion to be cylindrical. This allows the metal cushion to be designed in a space-saving manner taking into account the cross-sectional area of the existing coupling element and / or the surface required for force absorption.

[0020] To accommodate different loads on the rotor, two metal cushions cooperate to form a damping element, with the first metal cushion canceling out the first direction of rotor vibration and the second cushion canceling out the second, particularly opposite, direction of vibration. Since the metal cushions may be damaged or destroyed by tensile loads, they are designed to only receive compressive loads.

[0021] In an advantageous embodiment of the invention, the bearing unit includes at least one bearing having a bearing plate. The first metal cushion is arranged on one side of the bearing plate, and the second metal cushion is arranged on the second side of the bearing plate.

[0022] The guide pin may pass through the first metal cushion placed directly or indirectly on the bearing plate and the second metal cushion placed directly or indirectly on the bearing plate and the support element. One side of the guide pin is firmly connected to the support element. A head is provided on the other side of the guide pin, which is directly or indirectly adjacent to the first metal cushion. The first metal cushion, the bearing plate, and the second metal cushion are freely movable with respect to the guide pin. This ensures damping in opposite directions, which is necessary to dampen possible movements in these directions during operation, while only compressive loads are applied to each metal cushion.

[0023] Also, the damping elements of different bearings may have different designs. In particular, the damping element of the first bearing is optimized for damping, and the damping element of the second bearing is optimized for absorbing the weight force. For example, one damping element of the first bearing may include at least one metal cushion, and the other damping element of the second bearing may include at least natural / synthetic rubber.

[0024] This has the advantage that the bearing with the metal cushion can be essentially optimally designed for the damping required for the bearing unit of the centrifuge, and the bearing using natural rubber / synthetic rubber absorbs the load of the motor together with the rotor. This means, for example, that the lower and upper metal cushions are evenly loaded. This enables the use of metal cushions optimized for damping. In the design of the metal cushion, it is not necessary to consider the load of the motor together with the rotor. Basically, this means that it is not necessary to withstand the load of the motor and the rotor, and thus no preload is applied, so that smaller and softer metal cushions can be used.

[0025] Preferably, the spacing between the damping elements and / or the bearings adjacent to each other in the circumferential direction with respect to the drive shaft is the same.

[0026] Depending on the application, it may be advantageous for at least one spring axis of the damping element to be arranged perpendicular to the drive shaft.

[0027] Furthermore, or alternatively, at least one spring axis of the damping element may be arranged parallel to the drive shaft.

[0028] In one embodiment of the present invention, a plurality of bearings with damping elements are provided. Half of the spring axes of the damping elements are arranged perpendicular to the drive shaft, and the other half of the spring axes of the damping elements are arranged parallel to the drive shaft.

[0029] In this case, the spring axes of the damping elements may be alternately arranged perpendicular and parallel to the drive shaft.

[0030] Preferably, the damping element allows a maximum runout (or maximum displacement) of less than 2 mm, particularly less than 1.5 mm, in the region of the rotor, and / or allows a maximum runout of less than 1 mm, particularly less than 0.9 mm, in the region of the damping element.

[0031] For example, three damping elements may be provided, and the respective spring axes may be arranged in the same way.

[0032] In one embodiment of the present invention, a washer, particularly a metal washer, is used to delimit a damping element on one side in the direction of the spring axis. The washer ensures that the generated force is applied or transmitted across the entire cross-section of the damping element.

[0033] The washer may completely cover the damping element in the direction of the spring axis.

[0034] To prevent corrosion, the metal cushion is formed of a steel wire containing chromium and nickel. For this reason, the steel wire is a stainless steel wire.

[0035] Preferably, the diameter of the steel wire is from 0.05 mm to 0.5 mm. This range has been shown to provide optimal elastic deformation for the intended application.

[0036] For example, the outer diameter of the metal cushion may be from 12 mm to 50 mm.

[0037] In particular, the metal cushion may be designed as a hollow cylinder with a diameter of from 4 mm to 12 mm.

[0038] To optimize the requirements of an operating centrifuge as much as possible, the damping coefficient k of the metal cushion at a given excitation frequency is in the following range: - When the excitation frequency is 1 Hz, the damping coefficient k is 500 to 8,000 Ns / m; - When the excitation frequency is 10 Hz, the damping coefficient k is 300 to 5,000 Ns / m; - When the excitation frequency is 20 Hz, the damping coefficient k is 200 to 2,500 Ns / m; - When the excitation frequency is 50 Hz, the damping coefficient k is 80 to 1,200 Ns / m; - When the excitation frequency is 100 Hz, the damping coefficient k is 40 to 500 Ns / m.

[0039] In one embodiment of the present invention, the stiffness (c) of the metal cushion is in the range of 3 to 300 N / mm.

[0040] The advantages of using a metal cushion in a centrifuge are, in addition to the above damping characteristics, resistance to aging deterioration. There is no hardening or creep of the material. By using stainless steel, corrosion resistance against solvents, acids, oils, greases, liquids and dusts is achieved. Furthermore, such a metal cushion has high resistance to aging deterioration. The metal cushion has high unbalance resistance and requires almost no installation space, so it can be arranged relatively close to the motor and the rotor in the housing of the centrifuge. Also, by installing it under pressure, the reliability of operation is enhanced. While conventional rubber elements were cracked under tensile load, the metal cushion prevents tearing. Furthermore, the parameters of the metal cushion remain almost the same over the service life. Also, the parameters of the metal cushion do not change even when subjected to temperature fluctuations. Therefore, it can be used without problems in a heated engine compartment without affecting the operation of the centrifuge.

Brief Description of the Drawings

[0041] Further advantages, features and possible uses of the present invention will become apparent from the following description with reference to the embodiments shown in the drawings.

[0042] Throughout the specification, the claims and the drawings, these terms and related reference signs are used as described in the following list of reference signs.

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DETAILED DESCRIPTION OF THE INVENTION

[0043] Figures 1 to 5 are different views of five different embodiments of the laboratory centrifuge 10. Figure 1 shows the prior art, and Figures 2 to 5 show four different embodiments according to the present invention. In order to better visualize the essential elements of the present invention, not all components of the laboratory centrifuge 10 are shown in the drawings. Only those components necessary for understanding the present invention among the components of each individual embodiment are shown in the respective figures.

[0044] Figures 1a to 1f show a first embodiment of a prior art laboratory centrifuge 10.

[0045] Inside the housing 12 of the centrifuge, the motor 18 is arranged on the base plate 16 via three supports 20, 22 and 24. The base plate 16 has four integral feet 26 on the lower side thereof, and these feet 26 are provided in the corner regions of the base plate 16. The laboratory centrifuge 10 stands, for example, on a laboratory bench via its feet 26.

[0046] The housing 12 of the centrifuge closes the interior 14 at the top and has a recess 30 concentric with the motor shaft 28 through which the rotor 32 can be loaded.

[0047] The lid 34 of the centrifuge engages in the recess 30 in a specific area, thereby closing the interior 14. Ambient air flows into the interior 14 during operation of the laboratory centrifuge 10 via concentric ventilation holes 36 and another laterally arranged ventilation hole 38. For this purpose, the lid 34 of the centrifuge has a double-shell design and forms a flow path 34a between the concentric ventilation holes 36 and the laterally arranged ventilation holes 38. The lid 34 of the centrifuge is rotatably attached to the housing 12 of the centrifuge in a conventional manner.

[0048] Adjacent to the concentric recess 30 of the centrifuge housing 12 is a safety container 40, which is firmly connected to the centrifuge housing 12. The drive shaft 42 engages with the safety container 40 through a corresponding hole made in the bottom of the safety container. The rotor 32 is rotatably fixed and arranged on the drive shaft 42 connected to the motor 18. The rotor 32 is driven by the motor 18 in a known manner via the drive shaft 42.

[0049] The motor 18 is firmly attached to and disposed in the bearing unit 44. The bearing unit 44 is connected to the base plate 16 via the supports 20, 22, 24. For this reason, the bearing unit 44 has plate-like protrusions 44a, 44b, 44c respectively. More specifically, the plate-like protrusion 44a is associated with the support 20, the plate-like protrusion 44b is associated with the support 22, and the plate-like protrusion 44c is associated with the support 24. The supports 20, 22, 24 act to position the bearing unit 44 at a predetermined distance from the base plate 16.

[0050] The support 20 has a damping element in the form of a rubber cushion 20a and is supported by the base plate 16. The rubber cushion 20a is formed in a cylindrical shape. Threaded bolts 20b are attached to each end face of the rubber cushion 20a and fixed to the base plate 16. The lower surface of the plate-like protrusion 44a is supported by the upper surface of the rubber cushion 20a. A nut 20c screwed onto the bolt 20b and pressing against the upper surface of the plate-like protrusion 44a holds the bearing unit 44 at a predetermined position of the rubber cushion 20a of the support 20. A washer 20d is interposed between the nut 20c and the upper surface of the plate-like protrusion 44a. The supports 22 and 24 have the same structure.

[0051] The support 22 has a damping element in the form of a rubber cushion 22a and is supported by the base plate 16. The rubber cushion 22a is formed in a cylindrical shape. Threaded bolts 22b are attached to the end face of the rubber cushion 22a and fixed to the base plate 16. The lower surface of the plate-like protrusion 44b is supported by the upper surface of the rubber cushion 22a. A nut 22c screwed onto the bolt 22b and pressing against the upper surface of the plate-like protrusion 44b holds the bearing unit 44 at a predetermined position of the rubber cushion 22a of the support 22. A washer 22d is interposed between the nut 22c and the upper surface of the plate-like protrusion 44b.

[0052] The support 24 has a damping element in the form of a rubber cushion 24a and is supported on the base plate 16. The rubber cushion 24a is formed in a cylindrical shape. A threaded bolt 24b is attached to the end face of the rubber cushion 24a and is fixed to the base plate 16. The lower surface of the plate-shaped projection 44c is supported on the upper surface of the rubber cushion 24a. A nut 24c that is screwed onto the bolt 24b and presses against the upper surface of the plate-shaped projection 44c holds the bearing unit 44 at a predetermined position of the rubber cushion 24a of the support 24. A washer is interposed between the nut 24c and the upper surface of the plate-shaped projection 44b.

[0053] The rubber cushions 20a, 22a, and 24a each have a spring axis 20e, 22e, and 24e that is the same as the axis of the associated screws 20b, 22b, and 24b, and are aligned parallel to the motor shaft 28.

[0054] The motor 18 together with the drive shaft 42 and the rotor 32 is thus completely arranged within the bearing unit 44 and is supported thereby. These components are connected to the housing 12 of the centrifuge via the supports 20, 22, 24. The rubber cushions 20a, 22a, and 24a support the bearing unit 44 within the housing of the centrifuge and prevent the generation of noise. However, the damping characteristics are insufficient.

[0055] Figures 2a to 2f show a first embodiment of the laboratory centrifuge 10 according to the present invention. Hereinafter, the same reference numerals will be used to denote the same components. Furthermore, only the differences from the embodiments of the prior art will be described.

[0056] Referring to the embodiment of FIG. 1, in this case, different supports 46, 48, 50 are provided. The plate-like protrusions 44a, 44b, 44c are respectively supported by the first metal cushions 46a, 48a, 50a. These first metal cushions 46a, 48a, 50a are preloaded by the weights of the motor 18 and the rotor 32. Further, the first metal cushions 46a, 48a, 50a are slightly shorter than the rubber cushions 20a, 22a, 24a in FIG. 1 and are placed on the bearing shoulders 46f, 48f, 50f. The bearing shoulders 46f, 48f, 50f are respectively fixed to the base plate 16 by bolts. From the bearing shoulders 46f, 48f, 50f, the bolts 46b, 48b, 50b extend upward and pass through the plate-like protrusions 44a, 44b, 44c, the second metal cushions 46g, 48g, 50g having the same design as the first metal cushions 46a, 48a, 50a, and the washers 46d, 48d, 50d. The nuts 46c, 48c, 50c are screwed onto the bolts 46b, 48b, 50b and press the washers and the second metal cushions 46g, 48g, 50g. Further, second washers 46h, 48h, 50h are interposed between the second metal cushions 46g, 48g, 50g and the bearing shoulders 46f, 48f, 50f.

[0057] Thus, the first metal cushions 46a, 48a, 50a cancel (or counteract; or weaken) the downward movement, and the second metal cushions 46g, 48g, 50g cancel (or counteract; or weaken) the upward movement. Since they each receive only a compressive load, the optimal damping characteristics of the metal cushions can be exhibited.

[0058] Figures 3a to 3f show a second embodiment of the laboratory centrifuge 10 according to the present invention. Hereinafter, the same reference numerals will be used to denote the same components. Further, here, only the differences from the centrifuge of FIG. 1 and the first embodiment will be described.

[0059] This embodiment has a total of six supports, namely the three supports 20, 22, 24 according to FIG. 1 and the three supports 46, 48, 50 according to the first embodiment of the present invention. As a result, the bearing unit 44 has six plate-like protrusions 44d, 44e, 44f, 44g, 44h, 44i. More specifically, the protrusion 44d is associated with the support 20, the protrusion 44e is associated with the support 22, the protrusion 44f is associated with the support 24, the protrusion 44g is associated with the support 46, the protrusion 44h is associated with the support 48, and the protrusion 44i is associated with the support 50. The supports 20, 22, 24, 46, 48, 50 attached to the base plate 16 are arranged at equal intervals from each other and concentrically with the motor shaft 28. More specifically, in the counterclockwise direction, the support 46 is next to the support 20, the support 22 is next to the support 46, the support 48 is next to the support 22, the support 24 is next to the support 48, the support 50 is next to the support 24, and the support 20 is next to the support 50. As a result, the types of the supports 20, 22, 24 in FIG. 1 and the types of the supports 46, 48, 50 in the first embodiment of the present invention are arranged alternately. This has the advantage that the required damping of the bearing unit 44 of the centrifuge 10 is essentially achieved through the supports 46, 48, 50, the load of the motor combined with the rotor is absorbed by the bearings 20, 22, 24, and the lower and upper metal cushions are subjected to equal loads. Thereby, a metal cushion optimized for damping can be used. In the design of the metal cushion, it is not necessary to consider the load of the motor combined with the rotor.

[0060] Figures 4a to 4f show a third embodiment of the laboratory centrifuge 10 according to the present invention. Hereinafter, the same reference numerals are used to denote the same components. Further, only the differences from the first or second embodiment according to the present invention and the centrifuge 10 in FIG. 1 will be described here.

[0061] This embodiment, like the second embodiment, has a total of six supports, namely the three supports 20, 22, 24 shown in FIG. 1 and the three supports 52, 54, 56 having horizontal damping. The bearing unit 44 has three plate-like protrusions 44d, 44f, 44h for the supports 20, 22, 24. More specifically, the plate-like protrusion 44d is associated with the support 20, the plate-like protrusion 44f is associated with the support 22, and the plate-like protrusion 44h is associated with the support 24.

[0062] Between these three protrusions 44d, 44f, 44h of the bearing unit 44, bearing brackets 44j, 44k, 44l are provided. The bearing brackets 44j, 44k, 44l initially extend horizontally away from the bearing unit 44 and then extend vertically upward parallel to the motor shaft 28. Support plates 58, 60, 62 extending upward parallel to the motor shaft 28 from the base plate 16 are provided for each of the bearing brackets 44j, 44k, 44l at a radial distance from the motor shaft 28.

[0063] Starting from the support plates 58, 60, 62, second washers 52h, 54h, 56h, hollow cylindrical second metal cushions 52g, 54g, 56g, bearing brackets 44j, 44k, 44l, first metal cushions 52a, 54a, 56a, first washers 52d, 54d, 56d, and nuts 52c, 54c, 56c are arranged on the supports 52, 54, 56. Bolts 52b, 54b, 56b are fastened to the support plates 58, 60, 62 and extend through the second washers 52h, 54h, 56h, the hollow cylindrical second metal cushions 52g, 54g, 56g, the bearing brackets 44j, 44k, 44l, the first metal cushions 52a, 54a, 56a, and the first washers 52d, 54d, 56d. The nuts 52c, 54c, 56c are screwed onto the bolts 52b, 54b, 56b and press against the first washers 52d, 54d, 56d and the first metal cushions 52a, 54a, 56a.

[0064] The supports 20, 22, 24, 52, 54, 56 are arranged at equal intervals from each other on the base plate 16 concentrically with the motor shaft 28. In the counterclockwise direction, the support 52 is next to the support 20, the support 22 is next to the support 52, the support 54 is next to the support 22, the support 24 is next to the support 54, the support 56 is next to the support 24, and the support 20 is next to the support 56. Thus, the first type of supports 20, 22, 24 and the third type of supports 52, 54, 56 of the first embodiment are arranged alternately.

[0065] The supports 52, 54, 56 have spring shafts 52e, 54e, 56e. The spring shafts 52e, 54e, 56e of the supports 52, 54, 56 are aligned perpendicular to the motor shaft 28. Therefore, the supports cancel out the possible vibration of the motor 18 and the rotor 32.

[0066] Also, in this embodiment, damping is essentially achieved by the supports 52, 54 and 56. Since the metal cushion only receives the compressive load, its optimal damping characteristics can be exhibited. The rubber cushions 20a, 22a, 24a absorb the load of the motor together with the rotor. Thereby, a metal cushion optimized for damping can be used.

[0067] Figures 5a to 5f show a fourth embodiment of the laboratory centrifuge 10 according to the present invention. Hereinafter, the same reference numerals will be used to denote the same components. Further, here, only the differences from the first, second or third embodiment according to the present invention will be described.

[0068] The bearing unit 44 is formed in the same manner as in the first embodiment. However, in this embodiment, supports with different designs are used. Three supports 64, 66, and 68 are provided, each associated with the plate-like protrusions 44a, 44b, and 44c respectively. Mounting brackets 70, 72, and 74 are provided at a radial interval from the plate-like protrusions 44a, 44b, and 44c. Each mounting bracket 70, 72, and 74 extends vertically upward from the base plate 16 and then bends horizontally toward the motor shaft 28. The bearing unit 44 is supported via the mounting brackets 70, 72, and 74. Starting from the support plates 58, 60, and 62, second washers 64h, 66h, 68h, second metal cushions 64g, 66g, 68g, bearing brackets 70, 72, 74, first metal cushions 64a, 66a, 68a, first washers 64d, 66d, 68d, and nuts 64c, 66c, 68c are provided.

[0069] Bolts 64b, 66b, 68b are fastened to the plate-like protrusions 44a, 44b, 44c and extend through the second washers 64h, 66h, 68h, the hollow cylindrical second metal cushions 64g, 66g, 68g, the mounting brackets 70, 72, 74, the first metal cushions 64a, 66a, 68a, and the first washers 64d, 66d, 68d. Nuts 64c, 66c, 68c are screwed onto the bolts 64b, 66b, 68b and press the first washers 64d, 66d, 68d and the first metal cushions 64a, 66a, 68a.

[0070] The supports 64, 66, 68 are each provided with spring shafts 64e, 66e, 68e arranged parallel to the motor shaft 28. The bearing unit is not placed on the supports 20, 24, 26 as in the first embodiment, but is supported by the supports 64, 66, 68 via the mounting brackets 70, 72, 74. In this embodiment, the first holding cushions 64a, 66a, 68a are arranged above the mounting brackets 70, 72, 74, and the second holding cushions 64g, 66g, 68g are arranged between the plate-like protrusions 44a, 44b, 44c of the bearing unit 44 and the mounting brackets 70, 72, 74.

[0071] In this embodiment, the bearing unit 44 is suspended, and the bearing unit 44 is damped by the metal cushions 64a, 66a, 68a in one direction and by the metal cushions 64g, 66g, 68g in the other direction.

[0072] The metal cushions used in the embodiments of the present invention are cylindrical, and the outer diameter is in the range of 12 mm to 50 mm. The inner diameter is in the range between 4 mm and 12 mm. The washer completely covers the surface of the metal cushion. The bolt passes through the metal cushion so that the cushion can move freely with respect to the bolt.

[0073] The various embodiments may be used to optimize the various uses of the centrifuge 10. The metal cushion causes a maximum runout of less than 2 mm, especially less than 1.5 mm, at the level of the rotor. At the level of the metal cushion, the maximum runout is less than 1 mm, preferably less than 0.9 mm.

[0074] The metal cushion may be formed of a steel wire containing chromium and nickel, which is a stainless steel wire. The diameter of the steel wire is in the range of 0.05 mm to 0.5 mm.

[0075] The damping coefficient k of the metal cushion used in each embodiment is in the following range for a given excitation frequency: - When the excitation frequency is 1 Hz, the damping coefficient k is 500 - 8,000 Ns / m; - When the excitation frequency is 10 Hz, the damping coefficient k is 300 - 5,000 Ns / m; - When the excitation frequency is 20 Hz, the damping coefficient k is 200 - 2,500 Ns / m; - When the excitation frequency is 50 Hz, the damping coefficient k is 80 - 1,200 Ns / m; - When the excitation frequency is 100 Hz, the damping coefficient k is 40 - 500 Ns / m By using the aforementioned metal cushion instead of or in addition to the rubber elements that have been generally used so far, high unbalance resistance can be achieved in a small installation space.

[0076] This is evident from the following comparison between the metal cushion of the aforementioned type and the rubber elements conventionally used: In the rubber elements used, as the excitation frequency increases, the damping coefficient decreases from a very low value. From a frequency of about 30 Hz, the damping substantially disappears. Refer to FIG. 6. FIG. 6 is a diagram showing the runout of the motor shaft in the upper part (region of the rotor) and the lower part (bearing, i.e., region of the damping element).

[0077] The frequency spectrum is traversed as a function of time. The rotor is accelerated from a stationary state to the rated speed. Refer to FIG. 7.

[0078] As can be seen from FIG. 7, when using the metal cushion according to the present invention, the runout can be reduced from about 6 mm to about 1 mm. Conversely, in the same centrifuge, when the dimension (distance from the rotor to the centrifuge container) remains unchanged, the allowable unbalance can be significantly increased.

Explanation of Reference Numerals

[0079] 10 Laboratory centrifuge 12 Centrifuge housing 14 Inside the centrifuge housing 12 16 Base plate 18 Motor 20 Support - left - first type 20a Metal cushion 20b Bolt 20c Nut 20d Washer 20e Spring shaft 22 Support - front - first type 22a Metal cushion 22b Bolt 22c Nut 22d Washer 22e Spring shaft 24 Support - right - first type 24a Metal cushion 24b Bolt 24c Nut 24d Washer 24e Spring shaft 26 Legs of the base plate 16 28 Motor shaft / Rotor shaft 30 Recess of the housing 12 of the centrifuge 32 Rotor 34 Lid of the centrifuge 34a Flow path 36 Vent hole - Concentric 38 Vent hole - Side 40 Safety container 42 Drive shaft 44 Bearing unit for the motor 18 44a Plate - like protrusions related to the supports 20 and 46 respectively 44b Plate - like protrusions related to the supports 22 and 48 respectively 44c Plate - like protrusions related to the supports 24 and 50 respectively 44d Plate - like protrusion related to the support 20 44e Plate - like protrusion related to the support 46 44f Plate - like protrusion related to the support 22 44g Plate - like protrusion related to the support 48 44h Plate - like protrusion related to the support 24 44i Plate - like protrusion related to the support 50 44j Bearing bracket related to the support 52 44k Bearing bracket related to the support 54 441 Bearing bracket related to the support 56 46 Support - Left - Second type 46a First metal cushion 46b Bolt 46c Nut 46d First washer 46e Spring shaft 46f Bearing shoulder 46g Second metal cushion 46h Second washer 48 Support - Center - Second type 48a First metal cushion 48b Bolt 48c Nut 48d First washer 48e Spring shaft 48f Bearing shoulder 48g Second metal cushion 48h Second washer 50 Support - right - second type 50a First metal cushion 50b Bolt 50c Nut 50d First washer 50e Spring shaft 50f Bearing shoulder 50g Second metal cushion 50h Second washer 52 Support - left - third type 52a First metal cushion 52b Bolt 52c Nut 52d First washer 52e Spring shaft 52g Second metal cushion 52h Second washer 54 Support - center - third type 54a First metal cushion 54b Bolt 54c Nut 54d First washer 54e Spring shaft 54g Second metal cushion 54h Second washer 56 Support - right - third type 56a First metal cushion 56b Bolt 56c Nut 56d First washer 56e Spring shaft 56g Second metal cushion 56h Second washer 58 Support plate for support 52 60 Support plate for support 54 Support plate of the support 56 Support 64 First metal cushion 64a Bolt 64b Nut 64c First washer 64d Spring shaft 64e Second metal cushion 64g Second washer 64h Support 66 First metal cushion 66a Bolt 66b Nut 66c First washer 66d Spring shaft 66e Second metal cushion 66g Second washer 66h Support 68 First metal cushion 68a Bolt 68b Nut 68c First washer 68d Spring shaft 68e Second metal cushion 68g Second washer 68h Mounting bracket 70 Mounting bracket 72 Mounting bracket 74

Claims

1. a) a rotor (32) for receiving a container with the material to be centrifuged; b) a drive shaft (42) having a rotor (32) attached thereto; c) a motor (18) that drives the rotor (32) via a drive shaft (42); d) a bearing unit (44) comprising bearings (46, 48, 50, 52, 54, 56; 64, 66, 68) each having a damping element (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) including a spring shaft (46e, 48e, 50e; 52e, 54e, 56e; 64e, 66e, 68e); and e) a centrifuge (10), in particular a laboratory centrifuge, comprising a carrier element (16) for fixing a motor (18) in the centrifuge (10) via a bearing unit (44), at least one damping element is formed as a metal cushion (46a, 48a, 50a; 46g, 48g, 50g; 52a, 54a, 56a; 52g, 54g, 56g; 64a, 66a, 68a; 64g, 66g, 68g) made entirely of metal and including a wire knit having elastic properties; two metal cushions (46a, 48a, 50a; 46g, 48g, 50g; 52a, 54a, 56a; 52g, 54g, 56g; 64a, 66a, 68a; 64g, 66g, 68g) cooperate to form a damping element, the first metal cushion (46a, 48a, 50a, 52a, 54a, 56a; 64a, 66a, 68a) counteracting the run-out of the rotor (32) in a first direction, and the second metal cushion (46g, 48g, 50g; 52g, 54g, 56g; 64g, 66g, 68g) counteracting the run-out of the rotor (32) in a second direction; The bearing unit (44) comprises at least one bearing (46, 48, 50) with a bearing plate (44a, 44b, 44c; 44d, 44e, 44f; 44g, 44h, 44i; 44j, 44k, 44l), in which a first metal cushion (46a, 48a, 50a; 52a, 54a, 56a; 64a, 66a, 68a) is arranged on a first side of the bearing plate (44a, 44b, 44c; 44d, 44e, 44f; 44g, 44h, 44i, 44j, 44k, 44l) and a second metal cushion (46g, 48g, 50g; 52g, 54g, 56g; 64g, 66g, 68g) is arranged on a second side of the bearing plate (44a, 44b, 44c), The guide pins (46b, 48b, 50b; 52b, 54b, 56b; 64b, 66b, 68b) are connected to first metal cushions (46a, 48a, 50a; 52a, 54a, 56a; 64a, 66a, 68b) that are directly or indirectly placed on the bearing plates (44a, 44b, 44c; 44d, 44e, 44f; 44g, 44h, 44i; 44j, 44k, 44l). 8a), as well as through the bearing plates (44a, 44b, 44c; 44d, 44e, 44f; 44g, 44h, 44i; 44j, 44k, 44l) and second metal cushions (46g, 48g, 50g; 52g, 54g, 56g; 64g, 66g, 68g) mounted directly or indirectly on the carrier element (16), and through the guide pins (46b, 48b, 50b; 52b, 54b, 56b; 64b, 66b, 68b) has a head portion which is fixedly connected to the carrier element (16) on one side and which bears indirectly or directly against the first metal cushion (46a, 48a, 50a; 52a, 54a, 56a; 64a, 66a, 68a) on the other side, and the first metal cushion (46a, 48a, 50a; 52a , 54a, 56a; 64a, 66a, 68a), the bearing plate (44a, 44b, 44c) and the second metal cushion (46g, 48g, 50g; 52g, 54g, 56g; 64g, 66g, 68g) are freely movable relative to the guide pins (46b, 48b, 50b; 52b, 54b, 56b; 64b, 66b, 68b).

2. In the centrifuge according to claim 1, The second direction corresponds to a direction of deflection of the rotor (32) opposite to the first direction.

3. The centrifuge according to claim 1 or 2, A centrifuge, characterized in that the metal cushions (46a, 48a, 50a; 46g, 48g, 50g; 52a, 54a, 56a; 52g, 54g, 56g; 64a, 66a, 68a; 64g, 66g, 68g) are cylindrical.

4. A centrifuge according to any one of claims 1 to 3, 1. A centrifuge, characterized in that the damping elements (20a, 22a, 24a; 46a, 48a, 50a; 52a, 54a, 56a; 64a, 66a, 68a) of the different bearings (20, 22, 24; 46, 48, 50; 52, 54, 56; 64, 66, 68) are different in design, in particular the damping elements (46a, 48a, 50a; 52a, 54a, 56a; 64a, 66a, 68a) of the first bearing (46, 48, 50; 52, 54, 56; 64, 66, 68) are optimized in terms of damping and the damping elements (20, 22, 24) of the second bearing (20, 22, 24) are optimized in terms of absorbing gravitational forces.

5. 5. The centrifuge according to claim 4, A centrifuge, characterized in that one damping element comprises at least one metal cushion (46a, 48a, 50a; 52a, 54a, 56a; 64, 66, 68) and the other damping element (20a, 20b, 20c) comprises at least natural rubber.

6. A centrifuge according to any one of claims 1 to 5, A centrifuge characterized in that adjacent damping elements (20a, 20b, 20c; 46a, 48a, 50a; 52a, 54a, 56a; 64, 66, 68) are arranged at equal intervals from each other in a circumferential direction about a drive shaft (42).

7. A centrifuge according to any one of claims 1 to 6, A centrifuge, characterized in that at least one spring axis (52e, 54e, 56e) of the damping element is arranged perpendicular to the drive shaft (42).

8. A centrifuge according to any one of claims 1 to 7, A centrifuge, characterized in that at least one spring axis (20e, 20e, 20e; 46e, 48e, 50e; 64e, 66e, 68e) of the damping element (20a, 22a, 24a; 46a, 48a, 50a; 64a, 66a, 68a) is arranged parallel to the drive shaft (42).

9. 9. The centrifuge according to claim 7 or 8, A centrifuge comprising a plurality of bearings (20, 22, 24; 52, 54, 56) with damping elements (20a, 22a, 24a; 52a, 54a, 56a), the spring axes (52e, 54e, 56e) of half of the damping elements (52a, 54a, 56a) being arranged perpendicular to the drive shaft (42) and the spring axes (20e, 22e, 24e) of the other half of the damping elements (20a, 22a, 24a) being arranged parallel to the drive shaft (42).

10. 10. The centrifuge according to claim 7, A centrifuge characterized in that the spring axes (52e, 54e, 56e) of the damping elements (52a, 54a, 56a) are alternately arranged perpendicular to the drive shaft (42) and the spring axes (20e, 22e, 24e) of the damping elements (20a, 22a, 24a) are alternately arranged parallel to the drive shaft (42).

11. A centrifuge according to any one of claims 1 to 10, A centrifuge, characterized in that the damping elements (46a, 48a, 50a; 52a, 54a, 56a; 62, 64, 66) allow a maximum run-out of less than 2 mm, in particular less than 1.5 mm, in the area of ​​the rotor (32).

12. A centrifuge according to any one of claims 1 to 11, A centrifuge, characterized in that the damping elements (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) allow a maximum run-out of less than 1 mm, in particular less than 0.9 mm, in the area of ​​the damping elements (20a, 22a, 24a).

13. The centrifuge according to claim 1, A centrifuge comprising three damping elements (20a, 22a, 24a; 46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a), each having a spring axis (20e, 22e, 24e; 46e, 48e, 50e; 52e, 54e, 56e; 64e, 66e, 68e) arranged in the same direction.

14. The centrifuge according to any one of claims 1 to 13, A centrifuge, characterized in that a washer (20d, 22d, 24d; 46d, 48d, 50d; 52d, 54d, 56d, 64d, 66d, 68d), in particular a metal washer, delimits a damping element (20a, 22a, 24a; 46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) on one side in the direction of the spring axis (20e, 22e, 24e; 46e, 48e, 50e; 52e, 54e, 56e, 64e, 66e, 68e).

15. 15. The centrifuge of claim 14, A centrifuge, characterized in that the washer (20d, 22d, 24d; 46d, 48d, 50d; 52d, 54d, 56d, 64d, 66d, 68d) covers the entire damping element (20a, 22a, 24a; 46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) in the direction of the spring axis (20e, 22e, 24e; 46e, 48e, 50e; 52e, 54e, 56e, 64e, 66e, 68e).

16. The centrifuge according to claim 1, A centrifuge, characterized in that the metal cushions (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) are made of steel wire containing chromium and nickel.

17. 17. The centrifuge of claim 16, A centrifuge characterized in that the diameter of the steel wire is 0.05 mm to 0.5 mm.

18. The centrifuge according to claim 1, A centrifuge, characterized in that the outer diameter of the metal cushions (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) is between 12 mm and 50 mm.

19. The centrifuge according to claim 1, A centrifuge, characterized in that the metal cushion (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) is designed as a hollow cylinder, in particular with an inside diameter between 4 mm and 12 mm.

20. The centrifuge according to claim 1, The damping coefficient k of the metal cushions (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) is - 500 to 8,000 Ns / m when the excitation frequency is 1 Hz; - 300 to 5,000 Ns / m when the excitation frequency is 10 Hz; - 200 to 2,500 Ns / m when the excitation frequency is 20 Hz; - 80 to 1,200 Ns / m at an excitation frequency of 50 Hz; - 40 to 500 Ns / m at an excitation frequency of 100 Hz A centrifuge comprising:

21. The centrifuge according to claim 1, A centrifuge, characterized in that the stiffness (c) of the metal cushions (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) is between 3 N / mm and 300 N / mm.

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