EP3135381B1 - Centrifuge - Google Patents

Description

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

In centrifuges, especially laboratory centrifuges, sample material that is sensitive to temperature is often centrifuged. Usually, for example, when centrifuging biological material, a certain temperature, for example 37 ° C., must not be exceeded, since otherwise the properties of the material change.

During operation of the centrifuge, heat is generated due to the friction between the rotor and the air present in the interior of the centrifuge. The heat can be dissipated by indirect cooling. If sample temperatures below the ambient temperature are to be realized, the installation of a refrigeration system is required and the heat is removed from the outside of the safety boiler by a refrigerant. When sample temperatures above ambient, such as 37 ° C, are permitted, ambient air is typically passed through the centrifuge to dissipate heat. These fans are located inside a housing of the centrifuge and directed to heat transfer surfaces such as the outside of the safety boiler. However, this type of cooling requires high air flows to carry away the amounts of heat, which is technically complex and causes high noise emissions. Therefore, indirect cooling is mainly suitable for low power centrifuges.

For larger centrifuges without built-in refrigeration system is usually cooled directly. For example, the JP 2008284517 A or the JP 2008-307219 A a centrifuge in which air is sucked from the environment via a recess in a centrifuge lid. An arranged in a safety boiler rotor acts during operation of the centrifuge similar to a fan, in the region of the axis of rotation of the rotor creates a negative pressure, air above the rotor is aspirated and displaced by inflowing air, flows in the interior of the centrifuge on the safety boiler and on a arranged below the safety boiler drive motor and leaves the interior through an outlet opening on a rear side of the centrifuge.

This solution is inexpensive and easy. However, the noise emissions are considerable, as the air in the housing flows in undefined paths, forming air separation edges and the air following the lowest resistance leaves the housing on the shortest path. The sound generated inside the centrifuge during operation penetrates unhindered to the outside . arises at the air separation edges. Furthermore, the air is not necessarily evenly distributed in the interior of the centrifuge, in particular not specifically on the safety boiler. Therefore, a uniform heat extraction at the safety boiler and the drive motor is not guaranteed.

From the DE 103 55 179 A1 and the one DE 103 16 897 A1 Air-cooled centrifuges are also known in which air is sucked into the space via the cover and blown out into a channel which is located in the centrifuge housing. The channel is designed so that it leads vertically downwards on the outside of the boiler.

From the CN 202 191 968 U a generic centrifuge is known, which has baffles to guide the air flow around the safety boiler around.

Disadvantage of these solutions, however, is that the air flows only over a minimal area of the outside of the safety boiler and thus virtually no heat transfer can take place and it comes to air deflections of at least 90 ° in the safety boiler, which lead to noise emissions.

The object of the invention is, while avoiding the disadvantages mentioned, to develop a centrifuge such that both within the housing a uniform heat dissipation takes place on the safety boiler and the drive motor, as well as the noise emissions lowered and a simple assembly possible.

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

The dependent claims form advantageous developments of the invention.

The invention is based on the finding that by a noise-encapsulating parts encapsulating molding, which carries and fixes the safety boiler, a defined flow control of the cooling medium specifically calms the flow and can be targeted to the heat-conducting areas, so that by the additional use of the outer surface of the safety boiler as a heat-transferring surface, the air flow can be reduced while maintaining the cooling effect, and thus the noise emissions of the centrifuge are significantly reduced.

According to the invention, a channel is provided for the gaseous cooling medium, which runs at least in some areas helically around the safety boiler and at least forms a flow guide, which limits the channel in the radial direction and in the axial direction partially, so that at least in the area of the safety boiler a directed Flow around the safety boiler arises around. The cooling medium is continuously transferred from a turbulent flow in the region of the suction flow in a laminar flow, which has a significant reduction in noise emissions result. In addition, the course of the flow of the cooling medium can thereby be controlled so that a larger area of the outer wall of the safety boiler is overflowed, as is the case with a non-directional flow. This causes a more efficient cooling of the centrifuge. This makes the centrifuge more suitable for use in smaller rooms or in the immediate vicinity of the operator. In this case, the flow guide is formed at least by a molded part, which is designed in particular as a housing insert. This allows for flexible insertion and replacement of the flow guide and thus facilitates assembly. The safety boiler is mounted in the molded part or the molded parts by a clamp connection. This can be dispensed at least partially with other storage and fastening elements for the safety boiler. Preferably, the molded part and thus the housing insert holds the safety boiler or hold the molded parts and thus the housing inserts the safety boiler. This saves costs for production and maintenance of the centrifuge. The clamping of the elastic molded parts between the housing and the safety boiler prevents these components from being excited to vibrate, in particular when operating with imbalance, and thus emit noises. In addition, the molded part can be easily introduced into the housing, in particular a part of the molded part is clamped on the safety boiler, whereby it seals the channel laterally and prevents flow short circuit.

In addition to the already described effect of reducing the flow noise by reducing the flow velocity also allows, at least partially, embracing the noise-emitting components such as motor and rotor with the molding a noise encapsulation. In particular, in the embodiment in which the flow guide is helically guided around the safety boiler, the molded part acts as a muffler. From the inside of the centrifuge outgoing or caused by the flow of coolant in the channel sound waves and sound waves, which are reflected on the outside of the safety vessel in the channel, are directly absorbed in the channel up, down and out in the molding.

It is advantageous if the channel extends to just below the safety boiler. At low heights, the flow guide is designed to be more continuous in the area of the safety boiler. In particular, this has a constant slope.

Preferably, the suction opening is arranged in the centrifuge lid, and the cooling medium enters the interior axially. Thus, the intake and the supply of ambient air can be structurally very easily integrated into the centrifuge, whereby costs are saved.

In one embodiment, it has proven to be advantageous to arrange an intake opening below the rotor. This opens up further creative possibilities, in particular with regard to the supply of ambient air.

It is expedient that the flow guide is formed as a separate component from the housing. This allows the use of various low-cost materials for the production of the flow guide and adapted to the particular requirements installation in the centrifuge. This saves costs and increases the efficiency of the cooling of the safety boiler.

In order to simplify the repair or maintenance and, if necessary, to allow replacement of a differently shaped flow guide, it is advantageous if the flow guide is detachably connected to the housing.

It is advantageous if the flow guide is U-shaped, semicircular or V-shaped in cross-section. This minimizes drag in the duct and calms the coolant faster. The noise emissions can thereby be further reduced.

The heat extraction is particularly efficient when the flow guide is applied to the boiler. The flow guide has the effect of additional cooling elements, if they are conductive Material is formed. The flow guide thereby increases the heat transfer surface even further.

In an advantageous embodiment, the flow guide, in particular as part of a housing insert, tight against the safety boiler. The cooling medium then flows in the limited channel from all sides, whereby the boundary is formed by the safety boiler and the flow guide. The flow of the cooling medium can be controlled even more precisely, and the cooling medium flows directly over the safety boiler to be cooled, which is usually made of metal and thus has a good thermal conductivity. In addition, with appropriate design of the flow guide considerable ease of assembly, especially if the flow guide is part of a housing insert. At least in the region of the safety boiler, the flow guide forms a channel which runs helically, ie at an angle of inclination and at a constant distance from the rotor axis, at least in regions from top to bottom in the housing. Thus, the cooling medium can flow past the outer wall of the safety boiler almost over the entire surface. The efficiency of the cooling is thereby further increased.

In particular, the flow guide, at least in the area around the safety boiler, has a helically running design, which can be one or more continuous. The inclination is constant or increases. Thus, the flow of the coolant is calmed over a large distance. The noise emissions of the centrifuge are further reduced.

According to a further aspect of the invention, the inclination, the surface shape of the flow guide and the cross section of the channel are formed so that a laminar flow of the cooling medium in the channel is established. In particular, while the path of the cooling medium is extended and thus increases the frictional resistance, so that the speed of the cooling medium is reduced. Consequently, the noise emissions are reduced.

In a preferred embodiment, the flow guide forms an enlarging channel cross section at least in the area of the safety boiler. This also serves to reduce noise emissions, as the channel cross-section continuously increases in the direction of the outlet opening, resulting in a reduction of the flow velocity. This has a positive effect on the ease of use of the centrifuge.

It is advantageous if the molded part is made of foam, such as PUR, EPP, EPE or EPS. Foam moldings can be produced in exactly the desired shape, have sound-absorbing properties and are elastic and relatively inexpensive.

Preferably, the cross-section of the outlet opening is at least 150% of the smallest cross-sectional area of the channel. In practice, it has been shown that this reduces flow velocity in the region of the outlet opening and thus noise emissions are reduced.

In an advantageous development of the invention, the outlet opening is arranged axially above the lowest flow course of the cooling medium. For this purpose, the flow guide is guided upward from the lowest flow path to the outlet opening, so that the cooling medium again flows in the largely axial direction. This prevents that the noise generated by the engine can pass unhindered to the outside. This further reduces the noise emissions of the centrifuge.

It is also very favorable if the outlet opening is arranged above a drive motor for the drive shaft of the rotor. As a result, the above-described sound-insulating effect also relates to the drive motor. This allows a particularly efficient reduction of noise emissions.

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 seitliche Schnittansicht einer erfindungsgemäßen Zentrifuge;

Fig. 2

eine Schnittansicht der in Fig. 1 dargestellten Zentrifuge von vorne;

Fig. 3

eine perspektivische seitliche Teilschnittansicht der in den vorangehenden Figuren dargestellten Zentrifuge;

Fig. 4

eine Perspektivansicht eines Formteils in geteilter Ausführung, und

Fig. 5

die in Fig. 2 gezeigte Schnittansicht der Zentrifuge von vorne mit einer schematischen Darstellung der Luftströmung innerhalb der Zentrifuge.

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 sectional view of a centrifuge according to the invention;

Fig. 2

a sectional view of in Fig. 1 illustrated centrifuge from the front;

Fig. 3

a perspective partial side sectional view of the centrifuge shown in the preceding figures;

Fig. 4

a perspective view of a molded part in split execution, and

Fig. 5

in the Fig. 2 shown sectional view of the centrifuge from the front with a schematic representation of the air flow within the centrifuge.

Fig. 1 shows a centrifuge 10 according to the invention in a lateral sectional view, with a front side VS of the centrifuge 10 as seen from the viewer to the left side and a back side RS to the right side. The Figures 2 and 3 show the centrifuge 10 from different perspectives.

The centrifuge 10 is provided with a housing 12. The housing 12, on whose upper side a cover 16 is provided, delimits an inner space 24 of the centrifuge 10. In the inner space 24, a drive motor 36 is arranged, which via a drive shaft 37 a mounted on the drive shaft 37, rotatably connected thereto and above the Drive motor 36 mounted rotor 32 drives. The rotor 32 is surrounded by a rotationally symmetrical safety boiler 26 in order to minimize the risk of damage to the centrifuge 10 and contamination of the interior 24 and the environment in the event of a crash or a vessel breakage.

The safety boiler 26 is mounted on a motor housing 36 a surrounding the drive motor 36. Rotor 32, safety boiler 26, drive shaft 37 and drive motor 36 are arranged concentrically to a rotor axis R.

Between safety boiler 26 and motor housing 36a, a bellows 34 is provided for decoupling vibrations occurring during operation. In addition, the bellows 34 serves to seal a recess 27 provided in the safety boiler 26, through which the drive shaft 37 engages from below into the safety boiler 26.

In the interior 24 of the centrifuge 10, a molded part 38 is provided, which rests on all sides at least partially on the housing 12. In the area of the safety boiler 26, the inner diameter of the molded part 38 is substantially dimensioned such that the molded part 38 bears against the boiler wall, but a channel 41 extending helically around the safety boiler 26 relative to the rotor axis R is introduced, which extends from the guide 40 of FIG Shaped part 38 is partially limited. Viewed in cross section, the guide 40 is U-shaped. The channel 41 thus becomes radial outwardly and axially bounded by the guide 40 of the molding 38 and radially inwardly from the vessel wall 28. The molding 38 extends from the bottom of the upper Wandungsbreichs 12 a of the housing 12, on which the lid 16 is disposed in the closed state, to Bottom 12b of the housing. The molded part 38 surrounds the safety boiler 26 completely and is usually constructed of two parts, which are simply plugged into the housing 12 and enter into a clamping connection with the safety boiler 26. The safety boiler 26 is held only by the molded part 38. As a result, the channel 41 is laterally sealed to the safety vessel 26.

The integrated into the molding 38 guide 40 and thus the channel 41 rotates around the safety boiler 26. Below the safety boiler 26, the radial cross section gradually decreases until the guide 40 finally merges into a uniform cylindrical inner contour 39 of the molding 38. The diameter of the inner contour 39 corresponds approximately to the diameter of the safety vessel 26, wherein the molded part 38 is spaced from the motor housing 36 a and the safety vessel 26.

In the inner contour 39, an opening 42 pointing to the rear side RS of the centrifuge is introduced, to which an outlet channel 44 adjoins. The outlet channel 44 extends from the opening 42, initially in a first portion 44a orthogonal to the rotor axis R back to the back RS and is then guided adjacent to a rear wall 12a in a second portion 44b up to the level of the bellows 34 parallel to the rotor axis R. There, the outlet channel 44 opens into an outlet opening 44, which is introduced into the rear wall 12 a.

The lid 16 of the centrifuge 10 has an outwardly curved top wall 16a, a bottom wall 16b and four side walls 16c. In the side facing the rear side RS of the centrifuge 10 side wall 16c, a suction port 18 is introduced. In the bottom wall 16b an intake opening 20 is arranged so that it is concentric with the rotor axis R in the closed state of the lid 16. An intake passage 19 is inserted in the lid 16 connecting the suction port 18 and the suction port 20.

In the cover 16 associated upper side 12b of the housing 12 is concentric with the rotor axis R, an opening 14 is provided whose diameter is larger than the diameter of the rotor 32 so that the rotor 32 can be easily loaded and unloaded and also change and maintenance of the rotor 32 are easy to perform.

In the bottom wall 16b of the lid 16, a guide portion 22 is provided around the suction port 20, which engages in the opening 14 of the housing 12 when the lid 16 is closed. On the side facing the intake channel 19, the guide region 22 terminates flush with the bottom wall 16b, while on the side facing the rotor 32, starting from the rotor axis R, it extends radially obliquely downward. On the side facing the rotor 32, the guide region 22 forms a control surface 22a.

Air entering the intake passage 19 through the intake port 18 flows through the intake port 20 into the inner space 24 of the centrifuge 10. While a portion of the inflowing air flows axially to the rotor 32 immediately below the intake port 20, another portion of the air flow passes along the Control surface 22 a to the boiler wall 28, so that the air distributed after entering relatively evenly in the safety boiler 26.

Comparable with a fan, the rotor 32 generates by its rotation during operation, a negative pressure in the region above the rotor 32, whereby more air from the intake passage 19 in the lid 16 is sucked. The displaced by the subsequent air from the area above the rotor 32 air is placed in a spiral movement and flows through a formed between the boiler wall 28 and the housing 12 associated edge 22 b of the control surface 22 a gap 30 in the guide 40 Turning the rotor 32 in a clockwise direction, the guide 40 describes a two-speed, left-handed helix with a constant pitch of 100 mm. Thus, the air is guided in a homogeneous channel without air separation edges, and the turbulent flow after entering the air into the centrifuge 10 is increasingly converted into a laminar flow.

Below the safety vessel 26, the air flows from the guide 40 into the region of the interior space 24 delimited by the cylindrical inner contour 39 of the molded part 38, in which the drive motor 36 is arranged. The air flows around the motor housing 36a before it passes through the previously described outlet channel 44 to the outlet opening 46, through which it leaves the centrifuge 10. Due to the helical guide 40, the circulation movement of the cooling air is maintained even in the region of the inner space 24 bounded by the cylindrical inner contour 39 of the molded part 38. As a result, the motor housing 36a flows around in a circumferential direction of the motor housing 36a and thereby improves the cooling effect.

It is also conceivable to dispense with the second section 44b of the outlet channel 44, to guide the first section 44a to the housing 12, and to provide the outlet opening 46 there and to remove the air there from the centrifuge 10. However, the formation of the second portion 44b and the relative to the first portion 44a upwardly offset arrangement of the outlet opening 46 improve the sound insulation, the sound waves of the engine and by the rotation of the rotor 32 in motion offset air in the centrifuge 10 through this training and Arrangement of the outlet channel 44 better absorbed by the molding 38 as in a rectilinear guide the outlet channel 44th

Im in the FIGS. 1 to 3 illustrated embodiment, it is assumed that a comparatively low cooling capacity is required, so that ambient air is used as the cooling medium. Depending on the field of application, this air could still be actively cooled before it enters the intake opening 18, or carbon dioxide or nitrogen, for example, could be selected as the cooling medium.

Fig. 4 shows a perspective view of a molded part 38 in a split design with two axially symmetrical halves, wherein the viewer from the rear half of the mold half 38a and the front half of the mold half 38b. The split design facilitates the introduction of the molding 38 in the housing 12 of the centrifuge 10 and thus the assembly. The molded part 38 thus forms a housing insert.

The molded part 38 is made of PUR because of the good sound-insulating properties. Other foams such as EPP, EPE and EPS are well suited.

Here, the helical arrangement of the guide 40 is clearly visible.

Fig. 5 shows the in Fig. 2 reproduced sectional view of the centrifuge 10 from the front with a schematic representation of the air flow within the centrifuge 10th

The air for cooling enters from the outside via the intake opening 18, which can not be seen from this perspective, into the intake duct 19 arranged in the cover 16. Via the intake opening 20, the air flows into the safety boiler 26 and is distributed in the area between the rotor 32 and the control surface 22a provided on the underside of the cover 16. The air flows around the rotor 32 in regions, taking heat, and then passes through the gap 30 in the guide 40th

In the helically around the safety vessel 26 arranged around guide 40, the air is calmed due to the uniform channel shape and the constant tilt angle and increased in a laminar flow. The air from the boiler wall 28 takes heat.

Depending on where in relation to the circumferential angle of the safety boiler 26, the air has flowed into the guide 40, it passes after about 0.5 to 2 orbits of the safety boiler 26 in guide 40 in the lying below the safety boiler 26 interior 24 of the centrifuge 10, where it flows around the motor housing 36a of the drive motor 36 and also removes heat.

The air finally passes into the first section 44a of the outlet channel 44, which as described above is orthogonal to the rotor axis R, and on to the second section 44b, which is not visible from this perspective, and which is arranged parallel to the rotor axis R. About the likewise in Fig. 5 unrecognizable outlet opening 46, the heat-transporting air is blown out of the centrifuge 10.

LIST OF REFERENCE NUMBERS

10

centrifuge

12

casing

12a

Rear panel

14

opening

16

cover

16a

top wall

16b

bottom wall

16c

sidewalls

18

suction

19

intake port

20

Intake vent

22

guide region

22a

control surface

22b

edge

24

inner space

26

safety tank

27

recess

28

boiler wall

30

gap

32

rotor

34

bellow

36

drive motor

36a

motor housing

37

drive shaft

38

molding

38a, b

Mold halves

40

guide

41

channel

42

recess

44

outlet channel

44a

first part

44b

second part

46

outlet opening

R

rotor axis

VS

front

RS

back

Claims (13)

1. Centrifuge (10) comprising a housing (12), a rotor (32), a safety vessel (26) in which the rotor (32) is mounted on a drive shaft (37) that extends through the safety vessel (26), and a centrifuge lid (16) which delimits an interior space (24) of the housing (12), wherein the safety vessel (26) is provided in the interior space (24), a gaseous cooling medium enters the interior (24) via an intake opening (20), flows through the interior (24) and in doing so, is guided laterally past the safety vessel (26) and at least past part of the drive motor via the rotor (32), and exits the interior (24) of the housing (12) laterally through an outlet opening (46), wherein a duct (41) is provided for the gaseous cooling medium, which duct extends at least in part spirally around the safety vessel (26) and forms at least one flow guide (40) that partially delimits the duct (41) in the radial direction and in the axial direction, with the result that a directed flow in a direction around the safety vessel (26) is obtained at least in the area of the safety vessel (26), characterized in that the flow guide (40) is formed by at least one molded part (38), the safety vessel (26) is supported in the molded part (38) by means of a clamping connection, and that the safety vessel (26) is essentially only held in place by the molded part(s) (38).
2. Centrifuge according to claim 1, characterized in that the duct (41) extends to below the safety vessel (26).
3. Centrifuge according to claim 1, characterized in that the flow guide (40) spirals around the safety vessel (26) several times, in particular with a constant pitch.
4. Centrifuge according to any one of the preceding claims, characterized in that the flow guide (40) is designed as a component that is separate from the housing (12).
5. Centrifuge according to any one of the preceding claims, characterized in that the flow guide (40) is detachably connected to the housing (12).
6. Centrifuge according to any one of the preceding claims, characterized in that the flow guide (40) is U-shaped, semicircular or V-shaped in cross-section.
7. Centrifuge according to any one of the preceding claims, characterized in that the flow guide (40) is mounted on the safety vessel (26), or in that the flow guide (40) rests against the safety vessel (26).
8. Centrifuge according to any one of the preceding claims, characterized in that at least in the area where it spirals around the safety vessel (26), the flow guide (40) has a constant or increasing pitch with regard to the flow path.
9. Centrifuge according to claim 8, characterized in that the pitch, the surface finish of the flow guide (40) and the cross-section of the duct (41) have been chosen so as to enable laminar flow of the gaseous cooling medium through the duct (41).
10. Centrifuge according to any one of the preceding claims, characterized in that at least in the area of the safety vessel (26), said flow guide (40) features an increasing duct cross-section.
11. Centrifuge according to any one of the preceding claims, characterized in that the molded part (38) is made of foam material such as PUR, EPP, EPE or EPS.
12. Centrifuge according to any one of the preceding claims, characterized in that the cross-section of the outlet opening (46) is at least 150% of the smallest cross-sectional area of the duct (41).
13. Centrifuge according to any one of the preceding claims, characterized in that viewed axially, the outlet opening (46) is arranged above the deepest flow path of the cooling medium, or in that the outlet opening (46) is arranged above a drive motor (36) for the drive shaft (37) of the rotor (32).

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