EP3110557B1 - Centrifuge - Google Patents

Description

The invention relates to a centrifuge specified in the preamble of claim 1 species,

There are centrifuges in many forms known. Especially with laboratory centrifuges, efforts have always been made to propose devices which are as compact as possible, since the space available in laboratories is often limited. In addition, laboratory centrifuges are usually loaded and unloaded from above and therefore above the devices sufficient space must be available to open the lid.

At the same time it is necessary to pay attention to a good damping in the construction of a centrifuge in order to counteract inevitable occurring imbalances. In general, it is known, for example, to mount the motor for this purpose on damping elements whose spring axes are parallel to the longitudinal axis of the motor. However, the known arrangement and damping in practice has often proved inadequate. The damping elements in their previous arrangement can on the one hand absorb the resulting forces only poorly. On the other hand, the damping elements are loaded in a manner that shorten their life.

A generic centrifuge is from the DE 39 22 744 A1 known and has a rotor for receiving containers with centrifuging. Via a drive shaft, the rotor is driven, for which the drive shaft is connected to a motor. The motor with drive shaft and rotor are connected to a bearing unit which has a plurality of damping elements comprising a spring axis. The whole is connected to a support member for fixing the motor in the centrifuge. The spring axes of the damping elements can be employed at an acute angle σ to the axis of rotation Y of the motor. The damping elements are each connected via a strut with the bearing unit. The struts are employed and arranged so that they are concentrically aligned with the respective spring axis of the damping elements. The bearing unit comprises a support plate and cooperates with spring elements in addition to the damping elements.

From the GB 739 666 A and the US Pat. No. 1,848,641 A In each case, a centrifuge is known in which the motor is mounted on struts and damping elements in the housing.

The DE 195 16 904 A1 discloses a laboratory centrifuge with a vibration damping device,

The object of the present invention is to provide, while avoiding the disadvantages mentioned, a centrifuge, in particular a laboratory centrifuge, which is mounted so that the damping elements are optimally loaded and improved damping is achieved.

This object is achieved by the characterizing features of claim 1 in conjunction with its generic features.

The invention is based on the finding that in imbalance no tilting movement of the rotor takes place, but a wobbling motion. Up to now, an up and down movement has always been assumed due to the upward and downward movement of the rotor observed during operation. In fact, however, the forces do not act parallel to the axis of rotation. Rather, it concerns forces whose vectors are employed obliquely to the axis of rotation. By changing the position of the damping elements with respect to the support of the rotor or with respect to the motor can now achieve a more efficient damping and stabilize the centrifuge according to the invention.

According to the invention, the centrifuge has a rotor for receiving containers with Zentrifugiergut, a drive shaft on which the rotor is mounted, a motor which drives the rotor via the drive shaft, a bearing unit with a respective spring axis comprising damping elements and a support member for fixing the Engine over the storage unit in the centrifuge. The spring axes of the damping elements are employed at an acute angle σ to the axis of rotation of the motor. Since forces arising from the rotation of the rotor, especially in the occurrence of imbalance, resulting vibration, also act at an acute angle to the axis of rotation of the motor, this alignment of the damping elements has the advantage that the forces acting on the damping elements then mainly train and pressure forces are. Forces that place more strain on the damping elements and result in faster wear, such as shear forces, are minimized or eliminated by this arrangement. So can the life of the Damping elements are easily increased significantly and the damping can be significantly improved.

In this case, the bearing unit comprises a plurality of struts, preferably 3 to 21, which are connected to the damping elements and which are employed and arranged so that they are aligned concentrically with the respective spring axis. Due to the enlarged diameter at the bottom of the bearing unit a higher stability and thus an improved damping effect for the rotor are achieved.

In addition, the storage unit has a fixedly connected to the motor upper support plate and a firmly connected to the support member lower support plate. As a result, the bearing unit is stiffened and can better absorb and derive forces originating from the centrifuge.

Furthermore, the upper support plate and the struts are connected to each other via first spring elements. As a result, a part of the forces originating from the centrifuge is absorbed by the spring elements and, due to the uniform distribution of the spring elements over the circumference of the upper carrier plate, is delivered uniformly to the latter. This significantly improves the damping effect of the bearing unit.

It is favorable if the angle σ is in the range of 10 ° to 42 °, since experience shows that the forces originating from an imbalance and originating from the centrifuge act at an angle within this range with respect to the axis of rotation of the motor. Thus, a large part of these forces can be passed as tensile or compressive forces in the damping elements, and shear and bending forces are significantly reduced. This further reduces harmful loading of the damping elements and increases their life.

It is particularly advantageous if the angle σ is in the range of 15 ° to 25 °, since, as has been shown in numerous simulations, especially in laboratory centrifuges, the forces emanating from the centrifuge usually work in an angle lying within this range. This reduces the life of the damping elements detrimental shear and bending forces to a minimum,

In an advantageous embodiment, the damping elements between the struts and the lower support plate are arranged. Due to the increased spacing of the damping elements and the increased diameter change the leverage ratios in the bearing unit so that an improved damping effect is achieved.

In principle, all devices which damp vibrations, for example spring bearings, hydraulic bearings or magnetic bearings, can be used as damping elements. In particular, however, the use of rubber-metal elements has proven to be advantageous as a damper, since they are space-saving and inexpensive.

In an advantageous embodiment of the invention, the lower support plate and the damping elements are connected to each other via second spring elements. Again, a portion of the forces originating from the centrifuge is absorbed by the second spring elements, and due to the uniform distribution of the spring elements over the circumference of the lower carrier plate, the forces are delivered evenly to this. This improves the damping effect of the bearing element again.

In addition, if the mass element is connected by third spring elements with the struts, the mass element on the one hand stabilize the damping elements by its mass and on the other hand, similar to the upper and lower support plate, record horizontally extending forces and amplitude excursions and forward from strut to strut. As a result, the rigidity of the bearing element is further increased and the damping of the system is further improved.

It is advantageous if the mass element comprises two disk-shaped ground plates and an intermediate fixing plate. The disc-shaped design ensures optimal distribution of the mass and a small footprint. The structural separation between ground plates and fixing plate causes a simpler construction, since the struts need only be connected to the relatively thin fixing plate.

In a preferred embodiment of the invention, the first, second and / or third spring elements are formed as tabs which project from the associated plate, such as the upper support plate, the lower support plate and / or the fixing plate, and are elastically movable. Thereby, the connection between the plates and the struts or the damping elements is simplified. This facilitates in particular the assembly of the storage unit,

It is favorable if the tabs and the associated plates are made of metal. In the production, it is therefore possible to choose from a large number of metals and alloys and to respond well to the respective structural requirements of the centrifuge.

It is particularly advantageous if the upper support plate, the lower support plate and / or fixing plate are formed as an annular disc. Ring washers are easy to manufacture, and a uniform distribution of the struts or the damping elements over its circumference is easy to implement. This results in a good distribution of deflected over the tabs on the respective plates forces. The bearing element gains thereby stability and damping performance.

According to one aspect of the invention, at least one plate with its associated tabs is integrally formed by the upper support plate, the lower support plate and the fixing plate and in particular is formed of metal, preferably made of sheet steel. As a result, the production of the bearing element is easier and cheaper, since the number of its components is considerably lower. The tabs can be produced in a stamping and bending process with the carrier plate. Furthermore, results from the integral formation of plate and tabs improved stability of the bearing element.

To further increase the stability of the system, the motor may include mounting feet projecting from the motor housing, spaced equidistantly about the motor housing and through which the motor is fixedly connected to the bearing unit.

In a preferred embodiment of the invention, the motor is connected via the mounting feet with the upper support plate, wherein between the mounting feet tabs of the upper support plate are provided. Thus, a firm connection between the motor and bearing unit and a uniform distribution of the forces acting on the upper support plate are ensured in a compact design of the centrifuge.

Further advantages, features and possible applications of the present invention will become apparent from the following description in conjunction with the embodiments illustrated in the drawings.

Fig. 1

eine Seitenansicht der Zentrifuge ohne Gehäuse;

Fig. 2

eine perspektivische Ansicht der Zentrifuge mit Trägerelement, ohne Gehäuse;

Fig. 3

eine Seitenansicht der Lagereinheit;

Fig. 4

eine Draufsicht auf die Lagereinheit, und

Fig. 5

eine vertikale Schnittansicht der Zentrifuge ohne Rotor und Gehäuse.

In the description, the claims, and the drawing, the terms and associated reference numerals used in the list of reference numerals below are used. In the drawing:

Fig. 1

a side view of the centrifuge without housing;

Fig. 2

a perspective view of the centrifuge with carrier element, without housing;

Fig. 3

a side view of the storage unit;

Fig. 4

a plan view of the storage unit, and

Fig. 5

a vertical sectional view of the centrifuge without rotor and housing.

In Fig. 1 a laboratory centrifuge 10 is shown in side view. For better visibility of the invention essential elements is omitted in this and the other figures on the presentation of the centrifuge housing.

Along a longitudinal and rotational axis Y of a motor 18, which is at the same time the axis of rotation of the centrifuge 10, located at the upper end of a rotor 12 which receives container with centrifuging. The rotor 12 is supported on a motor shaft 14 which is driven by the underlying motor 18. The motor 18 is surrounded by a motor housing 24. The motor shaft 14 is via an upper bearing 16 and on the side facing the bearing a motor shaft 14 enclosing the lower bearing 22, see Fig. 5 , rotatably mounted in the motor housing 24. The motor shaft 14 is rotatably connected in a known manner with the rotor 12, for example via a Vielnutprofil not shown here.

On the side facing away from the rotor 12 side of the motor 18, the motor housing 24 is provided with equally spaced mounting feet 20, via which the motor 18 is fixedly connected to an upper support plate 32 of a bearing unit 30. The bearing unit 30 is used to support the motor 18 and the damping of forces resulting from the rotation of the rotor 12.

On the side facing away from the motor 18 side of the bearing unit 30 is a lower support plate 38. On the lower support plate 38 are provided as damping elements inclined rubber-metal elements 36, which in turn fixed at about the same angle struts 34 with the upper support plate 32 are connected. With respect to the longitudinal axis Y are as angles of incidence σ for the rubber-metal elements 36 and the associated struts 34 in principle angles between 10 ° and 42 ° advantageous because the forces based on imbalance, upon rotation of the rotor 12 in the region of this Angle act. For the present embodiment of the centrifuge 10, an angle of incidence σ of 21 ° has proven particularly suitable.

Furthermore, it is conceivable to carry out the bearing unit 30, for example, without the struts 34 and to connect the rubber-metal elements 36 directly to the upper support plate 32. However, it has been shown that a higher stability and thus an improved damping effect are achieved by the enlarged diameter at the bottom of the bearing unit 30. As damping elements incidentally come, for example, spring bearings, magnetic bearings or hydraulic bearings in question. However, a particularly favorable price / performance ratio have the rubber-metal elements 36 selected for this centrifuge 10.

Finally, between the upper support plate 32 and the lower support plate 38, a mass member 40 is provided, which is fixedly connected to the struts 34 and the rubber-metal elements 36. By the employment of the rubber-metal elements 36 and by the spacing of the rubber-metal elements 36 from the motor 18 by means of the struts 34, although a good damping effect is already achieved, so that the mass element 40 could also be dispensed with. By adding a mass element 40, however, the damping effect is further improved significantly.

The connections between the previously explained elements are described below with reference to Fig. 2 and Fig. 5 described.

Fig. 2 shows a perspective view of the centrifuge 10, which is arranged here on a support member 54. On the upper support plate 32, a first elastic tab 48 can be seen between each pair of mounting feet 20, each receiving the upper support plate 32 facing the end of a strut 34 and the respective strut 34 resiliently connects to the upper support plate 32. The first elastic tabs 48 may also be separate components that are welded to the upper support plate 32, for example. However, it increases the stability of the bearing unit 30 when the first elastic tabs 48, as in the illustrated embodiment, are formed integrally with the upper support plate 32 and the same material as the upper support plate 32, for example by a punching and bending process.

The lower boundary of the bearing element 30 is formed by a lower support plate 38, which is connected via second elastic tabs 50 with the rubber-metal elements 36. Between the lower support plate 38 and the upper support plate 32 is the mass element 40. The mass element 40 consists of three superimposed plates. In the middle of a fixing plate 44 is arranged, which is resiliently connected via third elastic tabs 52 with the rubber-metal elements 36 and with the struts 34. Above and below the fixing plate 44, a disk-shaped upper ground plate 42 and a disk-shaped lower ground plate 46 are arranged, both of which are fixedly connected to the fixing plate 44. The second elastic tabs 50 and the third elastic tabs 52 are formed in this embodiment, analogous to the first elastic tabs 48 integral with the respective associated lower support plate 38 and the fixing plate 44 and the same material as the respective associated plate.

The bearing unit is connected via the lower support plate 38 by screw 56 fixed to the support member 54. The support member 54 has at its four corners legs 58, with which the centrifuge 10 is on the ground.

Based on Fig. 3 in which the bearing unit 30 is shown in side view, now the damping effect of the bearing unit 30 will be explained. For better clarity, the mass element 40 is shown without the two ground plates 42 and 46.

As described above, forces from the rotating parts of the centrifuge 10, which arise, for example, from imbalances, act at an acute angle with respect to the axis of rotation Y. In simulations, it has been determined that this angle is in the range of 10 to 21 ° for the centrifuge according to the invention , In order to absorb the forces as efficiently as possible and to make the load on the damping elements as gentle as possible, the rubber-metal elements 36, which provide the main damping, are arranged at a corresponding angle of attack σ of 21 °. The rubber-metal elements 36 are connected via the second elastic tabs 50 fixed to the lower support member 38. In this case, the second elastic tabs 50 act as spring elements and increase the damping effect of the bearing unit 30.

In another embodiment of the centrifuge 10, the rubber-metal elements 36 may for example be attached directly to the upper support plate 32. However, in order to obtain an enlarged diameter at the bottom of the bearing unit and thereby achieve a higher stability and a still further improved damping effect, in the present embodiment, the rubber-metal elements 36 by the struts 34 from the upper support plate 32 spaced. In addition, to stabilize the bearing member 30 between the rubber-metal members 36 and the struts 34, the mass member 40 (in FIG Fig. 3 only shown by the fixing plate 44) is provided. The formed in the upper support plate 32 first elastic tabs 48 which connect the struts 34 fixed to the upper support plate 32, and formed in the fixing plate 44 third elastic tabs 52, the fixing plate 44 fixed to the struts 34 and the rubber-metal Connect elements 36, act as the second elastic tabs 50 as spring elements and increase the damping effect of the bearing unit 30 again. In particular, the forces to be absorbed are introduced, in particular via the third elastic tabs 52, between the struts 34 into a horizontal plane, into the mass element 40.

In Fig. 4 is a view from above of the bearing element 30 is shown. The not clearly recognizable from this perspective five struts 34 are bolted to the first elastic tabs 48 by hexagon screws 60. However, the number of struts 34 can be varied according to the respective requirements. Further, the upper support plate 32 has five holes 62 for screwing the mounting feet 20 of the motor 18 with the upper support plate 32. This will be in Fig. 5 explained.

Fig. 5 shows a schematic representation of a vertical section of the centrifuge 10. In contrast to Fig. 1 Here, the rotor 12 and two struts 34 are not shown for clarity. In this section, individual connections are illustrated.

The mounting feet 20 of the motor 18 are screwed by screw-nut connections 64 with the upper support plate 32. For this purpose, 20 holes 66 are provided in the mounting feet and holes 62 in the upper support plate 32, which are associated with each other.

The fixed connection between the upper support plate 32 and the struts 34 is achieved by the screwing of the hexagon screws 60 through mutually associated holes 70 in the first elastic tabs 48 and holes 72 in the upper support plate 32 facing ends of the struts 34.

The fixed connection between the fixing plate 44 and the struts 34 and the rubber-metal elements 36 is made by each one provided on the motor 18 side facing the rubber-metal elements 36 provided pin 74 through an associated bore 76 in the third elastic tab 52 passes and engages in an associated bore 78 in the strut 34. Due to the weight of the centrifuge 10 and the oblique position of the struts 34 and the rubber-metal elements 36, the positive connection between pin 74 and holes 76 and 78 is sufficiently stable.

The fixed connection between the rubber-metal elements 36 and the lower support plate 38 is achieved by screwing screws 80 through mutually associated bores 82 in the second elastic tabs 50 and bores 84 in the rubber-metal elements 36.

The fixed connection between the fixing plate 44, the upper ground plate 42 and the lower ground plate 46 is made by screw-nut connections 86, wherein in each case a screw a provided in the upper mass plate 42 bore 88, a provided in the fixing plate 44 bore 90 and provided in the lower ground plate 46 bore 92 passes through and is fixed with the associated nut.

LIST OF REFERENCE NUMBERS

10

centrifuge

12

rotor

14

motor shaft

16

warehouse

18

engine

20

mounting feet

22

lower camp

24

motor housing

30

storage unit

32

upper support plate

34

pursuit

36

Rubber-metal elements

36a

spring axis

38

lower carrier plate

40

mass element

42

upper ground plate

44

fixing

46

lower ground plate

48

first elastic tabs

50

second elastic tabs

52

third elastic tabs

54

support element

56

screw

58

mainstays

60

Hex bolts

62

drilling

64

Nut and bolt connections

66

drilling

70

drilling

72

drilling

74

spigot

76

drilling

78

drilling

80

screw

82

drilling

84

drilling

86

Nut and bolt connections

88

drilling

90

drilling

92

drilling

Claims (14)

1. Centrifuge (10), in particular a laboratory centrifuge, comprising

   a) a rotor (12) for receiving containers holding material to be centrifuged,

   b) a driveshaft (14) on which the rotor (12) is mounted,

   c) a motor (18) which drives the rotor (12) via the driveshaft (14),

   d) a bearing unit (30) with damping elements that each have a spring axis (36a), and

   e) a support element (54) for fixing the motor (18) in the centrifuge by means of the bearing unit (30),

   wherein the spring axes (36a) of the damping elements (36) are placed at an acute angle σ relative to the rotary axis Y of the motor (18), said bearing unit (30) comprises a plurality of struts (34), preferably 3 to 21, which are connected to the damping elements (36), wherein the struts are placed and arranged so as to be concentrically aligned with the respective spring axis, and wherein the bearing unit (30) has at least one support plate (32, 38) which cooperates with spring elements (48, 50), characterized in that an upper support plate (32), which is firmly connected to the motor (18), and a lower support plate (38), which is firmly connected to the support element (54), are provided, and that the upper support plate (32) and the struts (34) are connected to one another via first spring elements (48).
2. Centrifuge according to claim 1, characterized in that the angle σ is within a range of between 10° and 42°, preferably within a range of between 15° and 25°.
3. Centrifuge according to one of claims 1 or 2, characterized in that the damping elements (36) are arranged between the struts (34) and the lower support plate (38).
4. Centrifuge according to any one of the preceding claims, characterized in that the damping elements (36) are designed as spring bearings, hydraulic bearings, magnetic bearings or, in particular, as rubber-metal elements.
5. Centrifuge according to any one of the preceding claims, characterized in that the lower support plate (38) and the damping elements (36) are connected to one another via second spring elements (50).
6. Centrifuge according to any one of the preceding claims, characterized in that a mass element (40) is arranged between the upper support plate (32) and the damping elements (36) and is firmly connected to the struts (34).
7. Centrifuge according to claim 6, characterized in that the mass element (40) is connected to the struts (34) by means of third spring elements (52).
8. Centrifuge according to one of claims 6 or 7, characterized in that the mass element (40) comprises two disk-shaped mass plates (42, 46) and an intermediate fixation plate (44),
9. Centrifuge according to one of claims 7 or 8, characterized in that the first (48), second (50) and/or third spring elements (52) are formed as lugs that protrude from the associated plate, such as the upper support plate (32), the lower support plate (38) and/or the fixation plate (44), extend perpendicular to the spring axis (36) and are elastically movable.
10. Centrifuge according to claim 9, characterized in that said lugs (48, 50,52) and the associated plates (32, 38, 44) are made of metal.
11. Centrifuge according to any one of claims 8 to 10, characterized in that the upper support plate (32), the lower support plate (38) and/or the fixation plate (44) are designed as ring disks.
12. Centrifuge according to any one of claims 9 to 11, characterized in that at least one plate (32, 38, 44) of the upper support plate (32), the lower support plate (38) and the fixation plate (44) is integrally formed with its associated lugs (48, 50, 52), and is in particular made of metal, preferably sheet steel.
13. Centrifuge according to any one of the preceding claims, characterized in that the motor (18) includes mounting feet (20) that protrude from the motor housing (24), which feet are arranged evenly spaced from each other around the motor housing (24) and serve to firmly connect the motor (18) to the bearing unit (30).
14. Centrifuge according to claim 13 in combination with one or more of claims 9 to 12, characterized in that said motor (18) is connected to the upper support plate (32), with lugs (48) of the upper support plate (32) being provided between the mounting feet (20).

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