Centrifuge

Abstract

The invention relates to a centrifuge (10), in particular a laboratory centrifuge, having a) a rotor (32) for receiving containers having material for centrifuging, b) a drive shaft (42), on which the rotor (32) is mounted, c) a motor (18), which drives the rotor (32) via the drive shaft (42), d) a bearing unit (44) having bearings (20, 22, 24; 46, 48, 50, 52, 54, 56; 64, 66, 68), which each have damping elements (20a, 22a, 24a; 46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) comprising a spring axis (20e, 22e, 24e; 46e, 48e, 50e; 52e, 54e, 56e; 64e, 66e, 68e), and e) a carrier element (16) for fixing the motor (18) via the bearing unit (44) in the centrifuge (10). The invention is characterized in that at least one damping element is formed completely from metal and as a metal cushion (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) comprising a wire knit having elastic properties.

Claims

1-23. (canceled)

24. Centrifuge (10), in particular a laboratory centrifuge, comprising: a) a rotor (32) for receiving containers with material to be centrifuged, b) a drive shaft (42) on which the rotor (32) is mounted, c) a motor (18) which drives the rotor (32) via the drive shaft (42), d) a bearing unit (44) having bearings (46, 48, 50, 52, 54, 56; 64, 66, 68) which each have damping elements (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) comprising a spring axis (46e, 48e, 50e; 52e, 54e, 56e; 64e, 66e, 68e), e) a carrier element (16) for fixing the motor (18) via the bearing unit (44) in the centrifuge (10), and, at least one damping element is formed completely from metal and as a metal cushion (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) comprising a wire knit having elastic properties.

25. Centrifuge according to claim 24, characterized in that the metal cushion (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) is cylindrical in shape.

26. Centrifuge according to claim 24, characterized in that two metal cushions (46a, 48a, 50a; 46g, 48g, 50g; 52a, 54a, 56a; 52g, 54g, 56g; 64a, 66a, 68a; 64g, 66g, 68g) together form a damping element, wherein the first metal cushion (46a, 48a, 50a, 52a, 54a, 56a; 64a, 66a, 68a) counteracts a deflection of the rotor (32) in a first direction and the second metal cushion (46g, 48g, 50g; 52g, 54g, 56g; 64g, 66g, 68g) counteracts a deflection of the rotor (32) in a second, in particular opposite, direction.

27. Centrifuge according to claim 26, characterized in that 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), wherein on one side of the bearing plate (44a, 44b, 44c; 44d, 44e, 44f; 44g, 44h, 44i; 44j, 44k, 44l) the first metal cushion (46a, 48a, 50a; 52a, 54a, 56a; 64a, 66a, 68a) is arranged and on the second side of the bearing plate (44a, 44b, 44c) the second metal cushion (46g, 48g, 50g; 52g, 54g, 56g; 64g, 66g, 68g) is arranged.

28. Centrifuge of claim 27, characterized in that a guide pin (46b, 48b, 50b; 52b, 54b, 56b; 64b, 66b, 68b) extends through the first metal cushion (46a, 48a, 50a; 52a, 54a, 56a; 64a, 66a, 68a) which rests directly or indirectly against the bearing plate (44a, 44b, 44c; 44d, 44e, 44f; 44g, 44h, 44i; 44j, 44k, 44l), the bearing plate (44a, 44b, 44c; 44d, 44e, 44f; 44g, 44h, 44i; 44j, 44k, 44l) and the second metal cushion (46g, 48g, 50g; 52g, 54g, 56g; 64g, 66g, 68g) which rests directly or indirectly against the bearing plate (44a, 44b, 44c; 44d, 44e, 44f; 44g, 44h, 44i; 44j, 44k, 44l) and the carrier element (16), wherein the guide pin (46b, 48b, 50b; 52b, 54b, 56b; 64b, 66b, 68b) is fixedly connected to the carrier element (16) on one side and has a head on the other side which bears indirectly or directly against the first metal cushion (46a, 48a, 50a; 52a, 54a, 56a; 64a, 66a, 68a), wherein 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 pin (46b, 48b, 50b; 52b, 54b, 56b; 64b, 66b, 68b).

29. Centrifuge according to claim 24, characterized in that the damping elements (20a, 22a, 24a; 46a, 48a, 50a; 52a, 54a, 56a; 64a, 66a, 68a) of different bearings (20, 22, 24; 46, 48, 50; 52, 54, 56; 64, 66, 68) are designed differently, in particular the damping elements (46a, 48a, 50a; 52a, 54a, 56a; 64a, 66a, 68a) of a first bearing (46, 48, 50; 52, 54, 56; 64, 66, 68) are optimized with respect to damping, and the damping elements (20, 22, 24) of a second bearing (20, 22, 24) are optimized with respect to absorbing the weight force.

30. Centrifuge according to claim 29, 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.

31. Centrifuge according to claim 24, characterized in that adjacent damping elements (20a, 20b, 20c; 46a, 48a, 50a; 52a, 54a, 56a; 64, 66, 68) are equally spaced from one another in the circumferential direction relative to the drive axis (42).

32. Centrifuge according to claim 24, characterized in that at least one spring axis (52e, 54e, 56e) of a damping element is aligned perpendicular to the drive shaft (42).

33. Centrifuge according to claim 24, characterized in that at least one spring axis (20e, 20e, 20e; 46e, 48e, 50e; 64e, 66e, 68e) of a damping element (20a, 22a, 24a; 46a, 48a, 50a; 64a, 66a, 68a) is aligned in parallel to the drive shaft (42).

34. Centrifuge according to claim 32, characterized in that multiple bearings (20, 22, 24; 52, 54, 56) with damping elements (20a, 22a, 24a; 52a, 54a, 56a) are provided, wherein the spring axes (52e, 54e, 56e) of half of the damping elements (52a, 54a, 56a) are aligned perpendicular to the drive shaft (42), and the spring axes (20e, 22e, 24e) of the other half of the damping elements (20a, 22a, 24a) are aligned in parallel to the drive shaft (42).

35. Centrifuge according to claim 32, characterized in that alternatingly the spring axes (52e, 54e, 56e) of the damping elements (52a, 54a, 56a) are aligned perpendicular to the drive shaft (42) and the spring axes (20e, 22e, 24e) of the damping elements (20a, 22a, 24a) are aligned in parallel to the drive shaft (42).

36. Centrifuge according to claim 24, characterized in that the damping elements (46a, 48a, 50a; 52a, 54a, 56a; 62, 64, 66) permit a maximum deflection in the region of the rotor (32) of less than 2 mm, in particular of less than 1.5 mm.

37. Centrifuge according to claim 24, characterized in that the damping elements (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) permit a maximum deflection in the region of the damping element (20a, 22a, 24a) of less than 1 mm, in particular of less than 0.9 mm.

38. Centrifuge according to claim 24, characterized in that three damping elements (20a, 22a, 24a; 46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) are provided, the spring axis (20e, 22e, 24e; 46e, 48e, 50e; 52e, 54e, 56e; 64e, 66e, 68e) of each of which is aligned identically.

39. Centrifuge according to claim 24, characterized in that a washer (20d, 22d, 24d; 46d, 48d, 50d; 52d, 54d, 56d, 64d, 66d, 68d), in particular a metal washer, delimits the 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) on one side.

40. Centrifuge according to claim 39, 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).

41. Centrifuge according to claim 24, characterized in that the metal cushion (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) is formed by a steel wire that contains chromium-nickel.

42. Centrifuge according to claim 41, characterized in that the steel wire is from 0.05 mm up to and including 0.5 mm in diameter.

43. Centrifuge according to claim 24, characterized in that the outer diameter of the metal cushion (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) is from 12 mm up to and including 50 mm.

44. Centrifuge according to claim 24, 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 inner diameter of between 4 mm and 12 mm.

45. Centrifuge according to claim 24, characterized in that the damping coefficient k of the metal cushion (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) is between 500 and 8,000 Ns/m for an excitation frequency of 1 Hz; between 300 and 5,000 Ns/m for an excitation frequency of 10 Hz; between 200 and 2,500 Ns/m for an excitation frequency of 20 Hz; between 80 and 1,200 Ns/m for an excitation frequency of 50 Hz; between 40 and 500 Ns/m for an excitation frequency of 100 Hz.

46. Centrifuge according to claim 24, characterized in that the stiffness (c) of the metal cushion (46a, 48a, 50a; 52a, 54a, 56a, 64a, 66a, 68a) is in a range of between 3 N/mm and 300 N/mm.

Description

[0048] Throughout the description, the claims and the drawings, those terms and associated reference signs are used as are stated in the list of reference signs below. In the drawings,

[0049] FIG. 1a is a cutaway perspective view of the centrifuge with motor, rotor, safety vessel and prior art damping elements made of rubber;

[0050] FIG. 1b is a perspective partial view of FIG. 1a showing the motor mounted in the centrifuge housing with bearing plates and damping elements;

[0051] FIG. 1c is a longitudinal sectional view of FIG. 1a;

[0052] FIG. 1d is a partial cross-sectional view Z of FIG. 1c;

[0053] FIG. 1e is a cross-sectional view of FIG. 1a;

[0054] FIG. 1f is a sectional view from above, taken along line C-C of FIG. 1e;

[0055] FIG. 2a is a cutaway perspective view of the centrifuge with motor, rotor, safety vessel and damping elements according to a first embodiment of the invention;

[0056] FIG. 2b is a perspective partial view of FIG. 2a of the motor mounted in the centrifuge housing with bearing plates and damping elements according to a first embodiment of the invention;

[0057] FIG. 2c is a longitudinal sectional view of FIG. 2a;

[0058] FIG. 2d is a partial cross-sectional view Z of FIG. 2c;

[0059] FIG. 2e is a cross-sectional view of FIG. 2a;

[0060] FIG. 2f is a sectional view from above, taken along line C-C of FIG. 2e;

[0061] FIG. 3a is a cutaway perspective view of the centrifuge according to a second embodiment of the invention with the motor, rotor, safety vessel and damping elements of FIG. 2 in combination with the prior art damping elements of FIG. 1;

[0062] FIG. 3b is a perspective partial view of FIG. 3a of the motor mounted in the centrifuge housing with bearing plates and damping elements;

[0063] FIG. 3c is a longitudinal sectional view of FIG. 3a;

[0064] FIG. 3d is a partial cross-sectional view Z of FIG. 3c;

[0065] FIG. 3e is a cross-sectional view of FIG. 3a;

[0066] FIG. 3f is a sectional view from above, taken along line C-C of FIG. 3e;

[0067] FIG. 4a is a cutaway perspective view of the centrifuge according to a third embodiment of the invention with the motor, rotor, safety vessel and prior art damping elements of FIG. 1 and a further embodiment;

[0068] FIG. 4b is a perspective partial view of FIG. 4a of the motor mounted in the centrifuge housing with bearing plates and damping elements;

[0069] FIG. 4c is a longitudinal sectional view of FIG. 4a;

[0070] FIG. 4d is a partial cross-sectional view Z of FIG. 4c;

[0071] FIG. 4e is a cross-sectional view of FIG. 4a;

[0072] FIG. 4f is a sectional view from above, taken along line C-C of FIG. 4e;

[0073] FIG. 5a is a cutaway perspective view of the centrifuge according to a fourth embodiment of the invention with the motor, rotor, safety vessel and damping elements according to a further embodiment;

[0074] FIG. 5b is a perspective partial view of FIG. 5a of the motor mounted in the centrifuge housing with bearing plates and damping elements;

[0075] FIG. 5c is a longitudinal sectional view of FIG. 5a;

[0076] FIG. 5d is a partial cross-sectional view Z of FIG. 5c;

[0077] FIG. 5e is a cross-sectional view of FIG. 5a;

[0078] FIG. 5f is a sectional view from above, taken along line C-C of FIG. 5e;

[0079] FIG. 6 shows diagrams illustrating the deflection of the motor shaft at the top (in the area of the rotor) and at the bottom (in the area of the bearing, i.e. the damping elements); and

[0080] FIG. 7 shows diagrams illustrating the deflection of the axis of rotation with natural rubber elements and with metal cushions.

[0081] FIGS. 1 to 5 are different views of five different embodiments of a laboratory centrifuge 10, with FIG. 1 showing the prior art, and FIGS. 2 to 5 showing four different embodiments according to the invention. For better visibility of the essential elements of the invention, not all the components of the laboratory centrifuge 10 are shown in the drawings. Only those components of the individual embodiments that are necessary for understanding the invention are shown in the respective Figures.

[0082] FIGS. 1a to 1f show a first embodiment of a prior art laboratory centrifuge 10.

[0083] In an interior 14 of a centrifuge housing 12, a motor 18 is arranged on a base plate 16 via three supports 20, 22, and 24. The base plate 16 has four integral feet 26 on the underside of the base plate 16, which feet 26 are provided in the corner regions of the base plate 16. Via its feet 26, the laboratory centrifuge 10 stands on a lab bench, for example.

[0084] The centrifuge housing 12 closes off the interior 14 at the top and has a recess 30 concentric with a motor axis 28, through which a rotor 32 can be loaded.

[0085] A centrifuge lid 34 engages in the recess 30 in certain areas, thereby closing off the interior 14. Ambient air flows into the interior 14 via a concentrically arranged ventilation opening 36 and another laterally arranged ventilation opening 38 during operation of the laboratory centrifuge 10. For this purpose, the centrifuge lid 34 has a double-shell design, which creates a flow channel 34a between the lateral ventilation opening 38 and the concentric ventilation opening 36. The centrifuge lid 34 is pivotably mounted on the centrifuge housing 12 in a conventional manner.

[0086] Adjacent to the concentric recess 30 of the centrifuge housing 12 is a safety vessel 40, which is firmly connected to the centrifuge housing 12. A drive shaft 42 engages through the safety vessel 40 through a corresponding bore made in the bottom of the safety vessel. The rotor 32 is arranged in a rotationally fixed manner on the drive shaft 42 connected to the motor 18. The rotor 32 is driven in a known manner by the motor 18 via the drive shaft 42.

[0087] The motor 18 is firmly mounted and arranged in a bearing unit 44. The bearing unit 44 is connected to the base plate 16 via the supports 20, 22, 24. For this purpose, the bearing unit 44 has a plate-shaped projection 44a, 44b, 44c each. More specifically, plate-shaped projection 44a is associated with support 20, plate-shaped projection 44b is associated with support 22, and plate-shaped projection 44c is associated with support 24. The supports 20, 22, 24 act to position the bearing unit 44 at a predetermined distance from the base plate 16.

[0088] The support 20 has a damping element in the form of a rubber cushion 20a, which rests against the base plate 16. The rubber cushion 20a is formed as a cylinder. A threaded bolt 20b is attached to each end face of the rubber cushion 20a and is fastened to the base plate 16. The underside of the plate-shaped projection 44a rests against the upper side of the rubber cushion 20a. A nut 20c, which is screwed onto the bolt 20b and presses against the upper side of the plate-shaped projection 44a, retains the bearing unit 44 in place on the rubber cushion 20a of the support 20. A washer 20d is interposed between the nut 20c and the top of the plate-shaped projection 44a.

[0089] Supports 22 and 24 are of the same structure.

[0090] Support 22 has a damping element in the form of a rubber cushion 22a which rests against the base plate 16. The rubber cushion 22a is formed as a cylinder. A threaded bolt 22b is attached to the end faces of the rubber cushion 22a and is fastened to the base plate 16. The underside of the plate-shaped projection 44b rests against the upper side of the rubber cushion 22a. A nut 22c, which is screwed onto the bolt 22b and presses against the upper side of the plate-shaped projection 44b, retains the bearing unit 44 in place on the rubber cushion 22a of the support 22. A washer 22d is interposed between the nut 22c and the top of the plate-shaped projection 44b.

[0091] Support 24 has a damping element in the form of a rubber cushion 24a which rests against the base plate 16. The rubber cushion 24a is formed as a cylinder. A threaded bolt 24b is attached to the end faces of the rubber cushion 24a and is fastened to the base plate 16. The underside of the plate-shaped projection 44c rests against the upper side of the rubber cushion 24a. A nut 24c, which is screwed onto the bolt 24b and presses against the upper side of the plate-shaped projection 44c, retains the bearing unit 44 in place on the rubber cushion 24a of the support 24. A washer is interposed between the nut 24c and the top of the plate-shaped projection 44b.

[0092] The rubber cushions 20a, 22a, 24a each have a spring axis 20e, 22e, 24e that is identical to the axis of the associated screw 20b, 22b, 24b and is aligned in parallel to the motor axis 28.

[0093] The motor 18, with the drive shaft 42 and the rotor 32, is thus completely disposed within the bearing unit 44 and is supported by the latter. These parts are connected to the centrifuge housing 12 via the supports 20, 22, 24. The rubber cushions 20a, 22a, 24a support the bearing unit 44 in the centrifuge housing and prevent noise generation. Damping properties, however, are insufficient.

[0094] Illustrated in FIGS. 2a to 2f is a first embodiment of a laboratory centrifuge 10 according to the invention. In the following, the same reference signs will be used to denote the same parts. Moreover, only the differences with respect to the prior art embodiment will be addressed.

[0095] With reference to the embodiment of FIG. 1, different supports 46, 48, 50 are provided in this case. The plate-like projections 44a, 44b, 44c rest against a first metal cushion 46a, 48a, 50a each. These first metal cushions 46a, 48a, 50a are preloaded by the weight of the mass of the motor 18 and rotor 32. Moreover, the first metal cushions 46a, 48a, 50a are slightly shorter than the rubber cushions 20a, 22a, 24a of FIG. 1 and rest on a bearing shoulder 46f, 48f, 50f. The bearing shoulder 46f, 48f, 50f is respectively bolted to the base plate 16. From the bearing shoulder 46f, 48f, 50f, the bolt 46b, 48b, 50b extends upward, passes through the plate-shaped projection 44a, 44b, 44c, a second metal cushion 46g, 48g, 50g that is of identical design as the first metal cushion 46a, 48a, 50a, and the washer 46d, 48d, 50d. The nut 46c, 48c, 50c is screwed onto the bolt 46b, 48b, 50b and presses on the washer and the second metal cushion 46g, 48g, 50g. Furthermore, a second washer 46h, 48h, 50h is interposed between the second metal cushion 46g, 48g, 50g and the bearing shoulder 46f, 48f, 50f.

[0096] In this way, the first metal cushion 46a, 48a, 50a thus counteracts a downward movement and the second metal cushion 46g, 48g, 50g counteracts an upward movement. They are each only subjected to compressive loads, thus allowing the optimum damping properties of the metal cushions to take effect.

[0097] Illustrated in FIGS. 3a to 3f is a second embodiment of a laboratory centrifuge 10 according to the invention. In the following, the same reference signs will be used to denote the same parts. Moreover, only the differences with respect to the centrifuge of FIG. 1 and the first embodiment will be addressed here.

[0098] This embodiment has a total of six supports, namely three supports 20, 22, 24 according to FIG. 1 and three supports 46, 48, 50 according to the first embodiment of the invention. As a result, the bearing unit 44 has six plate-like projections 44d, 44e, 44f, 44g, 44h, 44i. More specifically, projection 44d is associated with support 20, projection 44e is associated with support 22, projection 44f is associated with support 24, projection 44g is associated with support 46, projection 44h is associated with support 48 and projection 44i is associated with support 50. The supports 20, 22, 24, 46, 48, 50 mounted on the base plate 16 equally spaced from one another and concentrically to the motor axis 28. More specifically, in a counterclockwise sense, support 46 is arranged next to support 20, support 22 is arranged next to support 46, support 48 is arranged next to support 22, support 24 is arranged next to support 48, support 50 is arranged next to support 24, and support 20 is arranged next to support 50. As a result, the type of supports 20, 22, 24 of FIG. 1 are alternatingly arranged with the type of supports 46, 48, 50 of the first embodiment of the invention. This has the advantage that the required damping of the bearing unit 44 of the centrifuge 10 is achieved essentially through the supports 46, 48, 50, and the bearings 20, 22, 24 thereby absorb the load of the motor with the rotor, so that the lower and upper metal cushions are subjected to equal loads. This allows the use of metal cushions that are optimized for damping. The load of the motor with the rotor need not be considered in the design of the metal cushions.

[0099] Illustrated in FIGS. 4a to 4f is a third embodiment of a laboratory centrifuge 10 according to the invention. In the following, the same reference signs will be used to denote the same parts. Moreover, only the differences with respect to the first or second embodiment according to the invention and the centrifuge 10 of FIG. 1 will be addressed here.

[0100] This embodiment, same as the second embodiment, has a total of six supports, namely three supports 20, 22, 24 according to FIG. 1 and three supports 52, 54, 56 with horizontal damping. The bearing unit 44 has three plate-shaped projections 44d, 44f, 44h for the supports 20, 22, 24. More specifically, plate-shaped projection 44d is associated with support 20, plate-shaped projection 44f is associated with support 22, and plate-shaped projection 44h is associated with support 24.

[0101] Between these three projections 44d, 44f, 44h of the bearing unit 44, bearing brackets 44j, 44k, 44l are provided. A bearing bracket 44j, 44k, 44l initially extends horizontally away from the bearing unit 44 and then vertically upward in parallel to the motor axis 28. At a radial distance relative to the motor axis 28, a support plate 58, 60, 62 extending upward from the base plate 16 in parallel to the motor axis 28 is provided for each of the bearing brackets 44j, 44k, 44l.

[0102] Starting from the support plate 58, 60, 62, a second washer 52h, 54h, 56h, a second hollow cylindrical metal cushion 52g, 54g, 56g, the bearing bracket 44j, 44k, 44l, a first metal cushion 52a, 54a, 56a, a first washer 52d, 54d, 56d, a nut 52c, 54c, 56c are arranged in the support 52, 54, 56. A bolt 52b, 54b, 56b is fastened to the support plate 58, 60, 62 and extends through the second washer 52h, 54h, 56h, the second hollow cylindrical metal cushion 52g, 54g, 56g, the bearing bracket 44j, 44k, 44l, the first metal cushion 52a, 54a, 56a, and the first washer 52d, 54d, 56d. The nut 52c, 54c, 56c is threaded onto the bolt 52b, 54b, 56b and presses against the first washer 52d, 54d, 56d and the first metal cushion 52a, 54a, 56a.

[0103] The supports 20, 22, 24, 52, 54, 56 are arranged at equal distances from one another on the base plate 16 concentrically to the motor axis 28, wherein, in a counterclockwise sense, support 52 is next to support 20, support 22 is next to support 52, support 54 is next to support 22, support 24 is next to support 54, support 56 is next to support 24, and support 20 is next to support 56. Thus, the first type of supports 20, 22, 24 of the first embodiment are alternatingly arranged with the third type of supports 52, 54, 56.

[0104] The supports 52, 54, 56 have spring axes 52e, 54e, 56e. The spring axes 52e, 54e, 56e of the supports 52, 54, 56 are aligned perpendicular to the motor axis 28. The supports therefore counteract possible deflections of the motor 18 and the rotor 32.

[0105] Also in this embodiment, damping is essentially achieved by the supports 52, 54 and 56. The metal cushions are again only subjected to compressive loads, so that the metal cushions can develop their optimum damping properties. The rubber cushions 20a, 22a, 24a absorb the load of the motor with the rotor. This allows the use of metal cushions that are optimized for damping.

[0106] Illustrated in FIGS. 5a to 5f is a fourth embodiment of a laboratory centrifuge 10 according to the invention. In the following, the same reference signs will be used to denote the same parts. Moreover, only the differences with respect to the first, second or third embodiments according to the invention will be addressed here.

[0107] The bearing unit 44 is formed in the same manner as the first embodiment. However, a different design of support has been used in this case. Three supports 64, 66, 68 are provided which are associated with the plate-shaped projections 44a, 44b, 44c, respectively. Radially spaced from the plate-shaped projection 44a, 44b, 44c is a mounting bracket 70, 72, 74. Each mounting bracket 70, 72, 74 extends vertically upward from the base plate 16 and is then angled horizontally toward the motor axis 28. The bearing unit 44 is supported via the mounting brackets 70, 72, 74. Starting from the support plate 58, 60, 62, a second washer 64h, 66h, 68h, a second metal cushion 64g, 66g, 68g, the bearing bracket 70 72, 74, a first metal cushion 64a, 66a, 68a, a first washer 64d, 66d, 68d and a nut 64c, 66c, 68c are provided.

[0108] A bolt 64b, 66b, 68b is fastened to the plate-shaped projection 44a, 44b, 44c, and extends through the second washer 64h, 66h, 68h, the second hollow cylindrical metal cushion 64g, 66g, 68g, the mounting bracket 70, 72, 74, the first metal cushion 64a, 66a, 68a, and the first washer 64d, 66d, 68d. The nut 64c, 66c, 68c is threaded onto the bolt 64b, 66b, 68b and presses against the first washer 64d, 66d, 68d and the first metal cushion 64a, 66a, 68a.

[0109] The supports 64, 66, 68 are each provided with a spring axis 64e, 66e, 68e, which is aligned in parallel to the motor axis 28. However, the bearing unit does not rest on the supports 20, 24, 26 according to the first embodiment, but is supported by the supports 64, 66, 68 via the mounting bracket 70, 72, 74. In this case, the first retaining cushion 64a, 66a, 68a is located above the mounting bracket 70, 72, 74, and the second retaining cushion 64g, 66g, 68g is arranged between the plate-shaped projection 44a, 44b, 44c of the bearing unit 44 and the mounting bracket 70, 72, 74.

[0110] In this embodiment, the bearing unit 44 is suspended and is damped by the metal cushions 64a, 66a, 68a in one direction and the metal cushions 64g, 66g, 68g in the other direction.

[0111] The metal cushions used in the described embodiments of the invention are cylindrical in shape and have an outer diameter ranging from 12 mm up to and including 50 mm. The inner diameter is in a range of between 4 mm and 12 mm. The washers completely cover the face of the metal cushion. The bolt passes through the metal cushion in such a way that the cushion remains free to move relative to the bolt.

[0112] The various embodiments can be used to optimize various applications of the centrifuge 10. The metal cushions cause a maximum deflection at the level of the rotor of less than 2 mm, in particular less than 1.5 mm. At the level of the metal cushions, the maximum deflection is less than 1 mm, preferably less than 0.9 mm.

[0113] The metal cushion may be formed by a steel wire that contains chromium-nickel, which makes it a stainless steel wire. The diameter of the steel wire is in a range from 0.05 mm up to and including 0.5 mm.

[0114] The damping coefficient k of the metal cushions used in each embodiment is in the following ranges for a given excitation frequency: [0115] for an excitation frequency of 1 Hz, the damping coefficient k is between 500 and 8,000 Ns/m; [0116] for an excitation frequency of 10 Hz, the damping coefficient k is between 300 and 5,000 Ns/m; [0117] for an excitation frequency of 20 Hz, the damping coefficient k is between 200 and 2,500 Ns/m; [0118] for an excitation frequency of 50 Hz, the damping coefficient k is between 80 and 1,200 Ns/m; [0119] for an excitation frequency of 100 Hz, the damping coefficient k is between 40 and 500 Ns/m;

[0120] The use of the metal cushions described above instead of, or in addition to, the rubber elements commonly used to date creates a high degree of imbalance tolerance in a small installation space.

[0121] This becomes apparent from the following comparison between a metal cushion of the type described above and a conventionally used rubber element:

[0122] In the rubber elements used, the damping coefficient decreases, starting from a very low value, as the excitation frequency increases. From a frequency of approx. 30 Hz, there is practically no damping left, see FIG. 6, i.e. diagrams depicting the deflection of the motor shaft at the top (in the area of the rotor) and at the bottom (in the area of the bearing, i.e. the damping elements).

[0123] The frequency spectrum is traversed as a function of time. The rotor is accelerated from standstill to rated speed, see FIG. 7.

[0124] As can be seen from FIG. 7, use of the metal cushions according to the invention allows deflection to be reduced from approx. 6 mm to approx. 1 mm. Conversely, in the same centrifuge, with unchanged dimensions (distance from rotor to centrifuge vessel), the permissible imbalance can be significantly increased.

LIST OF REFERENCE SIGNS

[0125] 10 laboratory centrifuge

[0126] 12 centrifuge housing

[0127] 14 interior of centrifuge housing 12

[0128] 16 base plate

[0129] 18 motor

[0130] 20 support—left—first type

[0131] 20a metal cushion

[0132] 20b bolt

[0133] 20c nut

[0134] 20d washer

[0135] 20e spring axis

[0136] 22 support—front—first type

[0137] 22a metal cushion

[0138] 22b bolt

[0139] 22c nut

[0140] 22d washer

[0141] 22e spring axis

[0142] 24 support—right—first type

[0143] 24a metal cushion

[0144] 24b bolt

[0145] 24c nut

[0146] 24d washer

[0147] 24e spring axis

[0148] 26 foot of base plate 16

[0149] 28 motor axis/rotor axis

[0150] 30 recess in centrifuge housing 12

[0151] 32 rotor

[0152] 34 centrifuge lid

[0153] 34a flow channel

[0154] 36 ventilation opening—concentric

[0155] 38 ventilation opening—lateral

[0156] 40 safety vessel

[0157] 42 drive shaft

[0158] 44 bearing unit for motor 18

[0159] 44a plate-shaped projection—associated with support 20 and 46 respectively

[0160] 44b plate-shaped projection—associated with support 22 and 48 respectively

[0161] 44c plate-shaped projection—associated with support 24 and 50 respectively

[0162] 44d plate-shaped projection—associated with support 20

[0163] 44e plate-shaped projection—associated with support 46

[0164] 44f plate-shaped projection—associated with support 22

[0165] 44g plate-shaped projection—associated with support 48

[0166] 44h plate-shaped projection—associated with support 24

[0167] 44i plate-shaped projection—associated with support 50

[0168] 44j bearing bracket—associated with support 52

[0169] 44k bearing bracket—associated with support 54

[0170] 44l bearing bracket—associated with support 56

[0171] 46 support—left—second type

[0172] 46a first metal cushion

[0173] 46b bolt

[0174] 46c nut

[0175] 46d first washer

[0176] 46e spring axis

[0177] 46f bearing shoulder

[0178] 46g second metal cushion

[0179] 46h second washer

[0180] 48 support—center—second type

[0181] 48a first metal cushion

[0182] 48b bolt

[0183] 48c nut

[0184] 48d first washer

[0185] 48e spring axis

[0186] 48f bearing shoulder

[0187] 48g second metal cushion

[0188] 48h second washer

[0189] 50 support—right—second type

[0190] 50a first metal cushion

[0191] 50b bolt

[0192] 50c nut

[0193] 50d first washer

[0194] 50e spring axis

[0195] 50f bearing shoulder

[0196] 50g second metal cushion

[0197] 50h second washer

[0198] 52 support—left—third type

[0199] 52a first metal cushion

[0200] 52b bolt

[0201] 52c nut

[0202] 52d first washer

[0203] 52e spring axis

[0204] 52g second metal cushion

[0205] 52h second washer

[0206] 54 support—center—third type

[0207] 54a first metal cushion

[0208] 54b bolt

[0209] 54c nut

[0210] 54d first washer

[0211] 54e spring axis

[0212] 54g second metal cushion

[0213] 54h second washer

[0214] 56 support—right—third type

[0215] 56a first metal cushion

[0216] 56b bolt

[0217] 56c nut

[0218] 56d first washer

[0219] 56e spring axis

[0220] 56g second metal cushion

[0221] 56h second washer

[0222] 58 support plate of support 52

[0223] 60 support plate of support 54

[0224] 62 support plate of support 56

[0225] 64 support

[0226] 64a first metal cushion

[0227] 64b bolt

[0228] 64c nut

[0229] 64d first washer

[0230] 64e spring axis

[0231] 64g second metal cushion

[0232] 64h second washer

[0233] 66 support

[0234] 66a first metal cushion

[0235] 66b bolt

[0236] 66c nut

[0237] 66d first washer

[0238] 66e spring axis

[0239] 66g second metal cushion

[0240] 66h second washer

[0241] 68 support

[0242] 68a first metal cushion

[0243] 68b bolt

[0244] 68c nut

[0245] 68d first washer

[0246] 68e spring axis

[0247] 68g second metal cushion

[0248] 68h second washer

[0249] 70 mounting bracket

[0250] 72 mounting bracket

[0251] 74 mounting bracket