EP3171982B1 - Centrifuge - Google Patents

Description

The invention relates to a centrifuge according to the specified in the preamble of claim 1. Art.

During operation of a centrifuge, unwanted heat is produced, which is detrimental to the product to be centrifuged. In particular, it is problematic that the centrifuge rotor, caused by its rotation and the resulting air friction a large part of the heat, is usually arranged for safety reasons in a tightly closed by a lid safety boiler. As a result, the heat from it is difficult to escape. Often biological samples are required to maintain a temperature of 4 ° C during centrifugation. Active cooling is therefore essential especially for longer operating times, high speeds and sample temperatures below the ambient temperature.

From the prior art, a plurality of generic centrifuges is known in which a compression refrigeration unit is provided. A refrigerant flows in a refrigeration circuit, which is separated by a throttle and a compressor in a high pressure and a low pressure area. After heat has been removed from the refrigerant in the high-pressure zone in a condenser, it flows in the low-pressure region in, for example, spirally arranged lines around a safety boiler in which the rotor of the centrifuge is arranged, thereby removing heat from the safety boiler.

Although this type of cooling is proven and reliable, it also has disadvantages. In particular, high safety standards must be observed in centrifuges because of the high kinetic energy that occurs during operation. Although flammable refrigerants ensure high efficiency of the cooling system. Because of the risk of a rotor crash and a breach of the wall of the safety boiler, which can also lead to sparking, but their use is under As a rule, fluorine-containing refrigerants, so-called F-gases, are used instead since they are not flammable. However, these F-gases have a high global warming potential, and their use is therefore successively restricted or prohibited by the legislature.

The JP H07 144 155 A is concerned with providing a centrifugal separator equipped with a water cooler capable of accurately controlling the temperature by controlling the air temperature in the bowl of the centrifuge by controlling the operation of a pump. A water cooler 20 is connected to a connecting pipe. A cooled cooling liquid is sent to the centrifugal separator to cool the air in the bowl. When the air in the bowl is regulated to a set temperature, an air temperature control in the bowl opens the contact of a relay and stops the supply of cooling liquid. When the temperature of the air in the bowl is increased again by the frictional heat due to the rotation of a rotor 1, the contact of the relay is closed when the air temperature in the bowl is raised to the temperature set by the regulator becomes the pump motor operated and cooling liquid is supplied to cool the air in the bowl. So the rotor is kept at a suitable temperature.

The DE 10 2012 002 593 A1 relates to a centrifuge with a compressor cooling device and a method for controlling a compressor cooling device of the centrifuge. The centrifuge comprises a centrifuge vessel and a compressor cooler having a refrigeration cycle, an evaporator, a condenser and a compressor. In the refrigeration cycle of the compressor cooling device, a controllable throttle device for controlling the refrigerant flow is provided.
The object of the invention is to provide, while avoiding the disadvantages mentioned, a centrifuge whose cooling is safe and at the same time safe both in terms of safety and environmental aspects.

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 by dividing the cooling circuit into a safety-critical area and a separate safety-critical area this task can be solved in a simple manner, especially if in the two areas different heat transfer medium - refrigerant - is used.

According to the invention, the centrifuge comprises a centrifuge housing, a safety vessel arranged in the centrifuge housing, an interior bounded by the safety boiler, a rotor arranged in the interior, and a cooling system arranged in the centrifuge housing for cooling the interior space. The cooling system comprises a compressor, a condenser and an evaporator, which are interconnected via conduit means. The cooling system in this case has a primary circuit with primary line means and a secondary circuit with secondary line means, wherein the primary circuit, the compressor, the condenser and the evaporator, which is part of a heat exchanger, and wherein the secondary circuit flows through the heat exchanger and cools the safety boiler. In order to ensure a constant flow of the heat transfer medium and thus an efficient cooling of the safety boiler, a pump is provided in the secondary circuit. Thus, it is possible to use different heat transfer media in the two circuits depending on the safety requirements, resulting in further design options to take targeted safety measures for the corresponding cycle.

In the primary circuit thereby flows a conventional combustible refrigerant, which has a large specific evaporation enthalpy at a relatively low cost.

With regard to the risk of a rotor crash and a breakdown of the safety boiler, however, it is advantageous in the secondary circuit that a non-combustible, heat transfer medium is used. The use of cooling water with additives that lower the freezing point, such as salt or alcohol, is inexpensive and environmentally friendly.

According to one aspect of the invention, the primary circuit is arranged below the secondary circuit and the safety boiler. This considerably reduces the risk of damaging the primary circuit in the event of a rotor crash and a breakthrough in the safety boiler.

If, however, the primary circuit is arranged laterally offset from the secondary circuit in the centrifuge housing, a significantly more compact design of the centrifuge can be realized, in particular with regard to the vertical extent.

In an advantageous embodiment of the invention, the two circuits spatially separating the safety wall is provided between the primary circuit and the secondary circuit. Thus, the risk of damage to the primary circuit in the event of a rotor crash and a breakdown of the safety boiler is further reduced if the primary circuit is arranged laterally offset to the secondary circuit.

It is advantageous if the safety boiler is fixed in the centrifuge housing via a clamping connection which, in the case of a rotor crash, enables a relative movement of the safety vessel relative to the centrifuge housing. In the event of a crash, a movement, in particular a rotary movement, of the safety boiler is initiated by the rotor engaging in the safety boiler or by the rotor parts impacting the safety boiler and the resulting angular momentum, which is braked by the clamping connection. The energy of the crash acting on the centrifuge housing is significantly attenuated or destroyed, which improves the protection of the primary circuit from damage.

According to a further aspect of the invention, at least one additional mass element is arranged to stabilize the centrifuge housing. This stabilization also serves to protect the primary circuit from the effects of the angular momentum that occurs during a rotor crash.

The protection of the primary circuit may be further improved by making the primary conduit means of a more mechanically strong material than the secondary conduit means.

In an alternative embodiment, predetermined breaking points are provided on the secondary conduit means. Thus, in the case of a particularly large pulse, which was caused by a rotor crash and can not be compensated sufficiently by a relative movement of the safety boiler relative to the centrifuge housing, the mechanical connection between the secondary circuit and the primary circuit separated and thereby prevents the impulse on the secondary Conduit is passed into the area of the primary circuit and causes damage there.

Preferably, the safety boiler is surrounded by a separate, in particular cylindrical, and concentric to the safety boiler protective wall. This further reduces the risk of damage to the primary circuit or centrifuge housing in the event of a rotor crash.

It is also advantageous if the aforementioned predetermined breaking points are provided at the locations where the secondary conduit means engage through the cylindrical protective wall. In this arrangement, the secondary conduit means are easily sheared by the protective wall in a relative movement, in particular rotational movement, of the safety boiler relative to the centrifuge housing.

A predetermined breaking point may, as stated, be formed in the secondary conduit means, for example by weakening a portion of the conduit means. Alternatively to the formation of a predetermined breaking point in the conduit means, the predetermined breaking point may also be formed solely by the assignment of a shearing device to a region of the conduit means. The shearing device is activated during a relative movement, in particular during a rotational movement, of the safety vessel, by moving the conduit means towards the shearing device and / or towards the shearing means towards the conduit means. In this case, the shearing device cuts through the conduit means in the area assigned to it. This solution is associated with little effort and has the advantage, inter alia, that in the secondary circuit less expensive conduit can be used, since the incorporation of weakened areas in the power resources is eliminated. Also, the installation of the conduit is easier, since the position of the predetermined breaking point is determined by the arrangement of the shearing device and not by a particular region of the conduit means.

In a further preferred embodiment, insulating and / or insulating materials are provided in the primary circuit, in particular between the compressor, the condenser and the evaporator. Insulating materials provide more stability, especially when a large external impulse is applied to the primary circuit. In particular, it is prevented that the compressor, which is mounted on elastic damping elements, can be torn from its anchorage and rupture pipelines. As a further positive feature insulating materials increase the efficiency of the refrigeration components. For example, hard foam moldings are well suited to meet these two tasks and serve as insulation and insulating material. It is particularly advantageous if the molded parts have integrated channels, which are used on the one hand for cable laying and on the other hand to a defined air flow.

A positive side aspect of this invention is that the requirements for the conduit means provided in the secondary circuit are still significantly lower than the requirements for the conduit means provided in the low pressure area of a conventional cooling apparatus with a refrigeration cycle. For one thing, the operating pressure in the secondary circuit of a cooling device according to the invention is still significantly lower than in the low-pressure region of a conventional cooling device. On the other hand, due to the separation of the two circuits, damage to the conduit in the secondary circuit poses no safety risks. Consequently, instead of rigid, massive and expensive conduit means such as copper pipes, for example, flexible hoses can be used. This reduces the design effort and lowers the cost 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 schematische Perspektivansicht einer erfindungsgemäßen Zentrifuge;

Fig. 2

eine schematische graphische Darstellung der beiden Kühlkreisläufe;

Fig. 3

eine seitliche Schnittansicht des Primärkreislaufs einer erfindungsgemäßen Zentrifuge mit Dämm- und Isolationselementen, und

Fig. 4

eine schematische Perspektivansicht einer erfindungsgemäßen Zentrifuge mit einem unterhalb des Sekundärkreislaufs angeordneten Primärkreislauf.

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 schematic perspective view of a centrifuge according to the invention;

Fig. 2

a schematic diagram of the two cooling circuits;

Fig. 3

a sectional side view of the primary circuit of a centrifuge according to the invention with insulating and insulating elements, and

Fig. 4

a schematic perspective view of a centrifuge according to the invention with a arranged below the secondary circuit primary circuit.

In Fig. 1 a schematic perspective view of a centrifuge 10 according to the invention is shown. For clarity, the housing is not shown; the arrangement of the housing cover 13a and the side walls 13b can the Fig. 3 be removed. A safety vessel 14 of the centrifuge 10 is arranged on a bottom plate 12 together with a compression refrigeration unit 20. The compression refrigeration unit 20 essentially comprises a compressor 22, a condenser 24, a fan 25, a filter drier 28 and an evaporator 26, which is part of a heat exchanger 30 which are interconnected via primary conduits 29 and a primary circuit 52 (see FIG Fig. 2 ) form. In the primary pipes 29, a combustible refrigerant 54 flows.

The safety boiler 14 is surrounded by only partially visible from this figure secondary pipes 34, which essentially a secondary circuit 62 (see Fig. 2 ) form. In the secondary pipes 34, a non-combustible heat transfer medium 64 flows.

The construction of primary circuit 52 and secondary circuit 62 is in Fig. 2 again illustrated by a schematic representation.

Concentrically around the safety vessel 14 around a protective cylinder 18 is arranged, which is fixed in particular horizontally by four clamping elements 38 which are fixed at equal intervals to each other on the outer periphery of the protective cylinder 18 on the bottom plate 12. From this perspective, however, only one clamping element 38 can be seen. In the case of a rotor crash, the protective cylinder 18 prevents widespread propagation of flying rotor parts, which can penetrate the centrifuge wall and cause great damage. For additional protection of the primary circuit 52 from penetrating rotor parts in the event of a crash, possibly even the Protective cylinder 18 could penetrate, a safety wall 36 is disposed on the bottom plate 12 between the safety boiler 14 and the compression refrigeration unit 20.

The secondary circuit 62 flows through the heat exchanger 30. To this end, two recesses 34a and 34b are provided in the safety wall 36, which are each penetrated by pipelines 34 of the secondary circuit 62. The pipe 34 extends from the safety boiler 14 through the recess 34b to the heat exchanger 30 by 62 heat is withdrawn from the secondary circuit. Between heat exchanger 30 and recess 34a, through which the pipe 34 extends back to the safety boiler 14, a pump 32 for conveying the non-combustible heat transfer medium 64 is arranged.

In Fig. 2 the principle of the two-circuit cooling of a centrifuge 10 according to the invention is shown schematically. On the cold side 60 is the secondary circuit 62, in which a non-combustible heat transfer medium 64 circulates. The heat transfer medium 64 is guided in secondary pipes 34 to a safety boiler 14, whereby the safety boiler 14 heat is removed. Furthermore, the pump 32 is provided, which promotes the heat transfer medium 64.

On the hot side 50 is the primary circuit 52, in which a combustible refrigerant 54 flows, with the compression refrigeration unit 20, which includes the compressor 22, the condenser 24, the fan 25, the throttle 28 and the evaporator 26, which via primary pipelines 29th connected to each other.

The evaporator 26 is part of a heat exchanger 30, which is also traversed by the pipes 34 of the secondary circuit 62. Thus, the primary circuit 52 and the secondary circuit 62 are thermally coupled via the heat exchanger 30. The heat extracted from the safety boiler 14 is transferred from the non-combustible heat transfer medium 64 from the secondary circuit 62 in the heat exchanger 30 to the combustible refrigerant 54 in the primary circuit 52. The transferred heat is released from the combustible refrigerant 54 via the condenser 24 to the ambient air 56. The heat release is improved by the use of the fan 25. Compression refrigeration units are known in principle, so that further explanations are unnecessary.

In Fig. 3 is a side partially sectioned view of the in Fig. 1 shown primary circuit 52 of the centrifuge 10 from the perspective of the secondary circuit 62 shown. As already in Fig. 1 The compressor 22, the condenser 24 with the associated fan 25, the filter drier 28 and the evaporator 26, not shown here, are connected to each other via primary pipelines 29. The primary circuit 52 is, as well as in Fig. 3 Secondary circuit 62, not shown, surrounded by a cuboid housing 13, which at the bottom of a bottom plate 12, at the top of a housing cover 13a and between the bottom plate 12 and the housing cover 13a side walls 13b, 13c. In the condenser 24 adjacent region of the side wall 13c ventilation slots 24a are provided.

In the space between the housing 13 and the elements of the primary circuit 52 with the largest spatial extent, ie in particular compressor 22, condenser 24, fan 25 and - not shown here - evaporator 26, is for the purpose of isolation and damping of vibrations a rigid foam molding 40 arranged. The shape of the hard foam molding 40 is the housing 13 and partially adapted to the profile of said elements of the primary circuit 52. In this case, the rigid foam molding 40 extends horizontally between the side walls 13b and 13c along the housing cover 13a and vertically partially along the side walls 13b and 13c and partially along the profile of said elements of the primary circuit 52. The vertical extension of the foam molding 40 is based on the structural conditions of Adjusted primary circuit and selected so that it is easy to bring and surrounds about the upper third of the compressor 22 and at the same time rests at least on the upper side of said elements of the primary circuit 52. The compressor 22, for example, surrounds the hard foam molding 40 approximately in the upper third of its vertical extent. Furthermore, 40 channels 42 are provided in the rigid foam molding, in which run primary pipes 29.

The centrifuge 10 stands on four feet 46 fastened on the underside of the bottom plate 12 on a substrate, two of which feet 46 are located below the primary circuit. To increase the stability, a rectangular mass element 44 is also approximately centrally mounted on the underside of the bottom plate 12.

In Fig. 4 an alternative embodiment of a centrifuge 10 according to the invention is shown, in which a secondary circuit 62 is arranged above a primary circuit 52. For clarity, no housing is shown here.

The primary circuit 52 is arranged on a rectangular bottom plate 70 with two end faces 72 and two longitudinal sides 74. Structure and function are identical to those in the FIGS. 1 to 3 described primary circuit 52 and therefore require no further explanation. At the edges of the bottom plate 70, a frame 76 is fastened by means of screws 88, which serves for the attachment of side walls of the not shown here housing and the other stable attachment of a false bottom 90 with two end faces 92 and two longitudinal sides 94, on which the secondary circuit 62 is arranged. The frame 76 comprises two rectangular frame parts 78, each having two end faces 80 and two longitudinal sides 82a and 82b, which are arranged between the two end faces 72 of the bottom plate 70 and the two end faces 92 of the intermediate bottom 90. The longitudinal sides 82a are fixedly connected by screws 88 to the bottom plate 70, and the longitudinal sides 82b are fixedly connected to the intermediate bottom 90 by means of screws 88. The frame 76 further includes two horizontally extending frame members 84 fixedly connected to the bottom plate 70 at each of its two longitudinal sides 74 by screws 88, and four vertical frame members 86. The vertically extending frame members 86 extend from the four corners of the bottom plate 70 to the four corners of the false bottom 90. To improve the stability, the frame members 86 have two perpendicular legs 87a and 87b, which are formed in one piece and of uniform material. The legs 87a are each arranged between the end face 72 of the bottom plate 70 and the end face 92 of the intermediate bottom 90, and the legs 87b are each arranged between the longitudinal side 74 of the bottom plate 70 and the longitudinal side 94 of the intermediate bottom 90. At the intermediate bottom 90 are - among other things for fastening of side walls of the not shown here - housing 92 horizontal frame members 96 and fixed on both sides 94 horizontal frame members 98 by means of screws 88.

The arranged on the intermediate bottom 90 secondary circuit 62 corresponds in its construction and its function substantially in the FIGS. 1 to 3 Therefore, further explanations are unnecessary. Only the guide of the secondary pipes 34 is changed due to the vertically superimposed arrangement of the primary circuit 52 and the secondary circuit 62 to each other accordingly. The safety vessel 14 and the surrounding protective cylinder 18 are mounted on a holding device 100 which is fixedly connected to the intermediate bottom 90 and to the horizontal frame members 98 and the horizontal frame members 96. For additional stabilization 90 carrier struts 102 are provided below the intermediate floor, which extend parallel to the end faces 92 and are fixedly connected to the intermediate bottom 90 and the horizontal frame members 98 by means of screws 88.

LIST OF REFERENCE NUMBERS

10

centrifuge

12

baseplate

13

casing

13a

housing cover

13b, 13c

side walls

14

safety tank

16

inner space

18

protective cylinder

20

Compression refrigeration unit

22

compressor

24

capacitor

25

fan

26

Evaporator

28

filter dryer

29

primary piping

30

heat exchangers

32

pump

34

secondary piping

34a

recess

34b

recess

36

safety wall

38

clamping elements

40

Foam molding

42

channels

44

mass element

50

warm side

52

Primary circuit

54

flammable refrigerant

56

Ambient air (UL)

60

cold side

62

Secondary circuit

64

non-combustible heat transfer medium

70

baseplate

72

front sides

74

long sides

76

frame

78

frame parts

80

front sides

82a, 82b

long sides

84

horizontally extending frame element

86

vertically extending frame element

88

screw

90

false floor

92

front sides

94

long sides

96

horizontal frame elements

98

horizontal frame elements

100

holder

102

support beams

Q ₁

Heat flow cold side

Q ₂

Heat flow warm side

Claims (10)

1. Centrifuge (10) having a centrifuge housing (13), a safety vessel (14) arranged in the centrifuge housing (13), an interior space (16) at least partially delimited by said safety vessel (14), a rotor arranged in the interior space (16), and a cooling system arranged in the centrifuge housing (13) for cooling the interior space (16), having a compressor (22), a condenser (24) and an evaporator (26), which are connected to one another via conduit means, characterized in that the cooling system has a primary circuit (52) with primary conduit means (29) and a secondary circuit (62) with secondary conduit means (34), wherein said primary circuit (52) comprises the compressor (22), the condenser (24) and the evaporator (26), which is part of a heat exchanger (30), wherein said secondary circuit (62) flows through the heat exchanger (30), cools the safety boiler (14) and includes a pump (32), and wherein a combustible refrigerant (54) flows in the primary circuit (52) and a non-combustible heat transfer medium (64) flows in the secondary circuit (62).
2. Centrifuge according to claim 1, characterized in that the primary circuit (52) is arranged below the secondary circuit (62) and the safety vessel (14).
3. Centrifuge according to claim 1 or claim 2, characterized in that within the centrifuge housing (13), the primary circuit (52) is arranged laterally offset with respect to the secondary circuit (62).
4. Centrifuge according to claim 3, characterized in that a safety wall (36) is provided between the primary circuit (52) and the safety vessel (14) for spatially separating them from one another.
5. Centrifuge according to any one of the preceding claims, characterized in that the safety vessel (14) is fixed in the centrifuge housing (13) via a clamping connection which, in the event of a crash, permits relative movement of the safety vessel (14) with respect to the centrifuge housing (13).
6. Centrifuge according to any one of the preceding claims, characterized in that at least one additional mass element (44) is arranged on the centrifuge housing (13) in order to stabilize the centrifuge housing (13).
7. Centrifuge according to any one of the preceding claims, characterized in that the primary conduit means (29) are made of a material that is mechanically stronger than the material of the secondary conduit means (34).
8. Centrifuge according to claim 7, characterized in that predetermined breaking points are provided on the secondary conduit means (34).
9. Centrifuge according to any one of the preceding claims, characterized in that the safety vessel (14) is surrounded by a protective wall (18) that is separate from the safety vessel (14).
10. Centrifuge according to any one of the preceding claims, characterized in that damping and/or insulating materials (40) are provided in the primary circuit (52), in particular between the compressor (22), the condenser (24) and the evaporator (26).

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