Temperature-controlled centrifuge with protective gas release in case of rotor crash

Abstract

A centrifuge (10) and a method for preventing the ignition of combustible temperature control media in centrifuges (10) after a crash of the centrifuge rotor are presented. Ignition is prevented by the release of a protective gas in the event of a crash. More precisely, the released protective gas forms a flow that displaces the oxygen, distributes the escaping temperature control medium and fundamentally changes the momentary ratio of the concentration of oxygen to temperature control medium in such a manner that no ignition can take place either inside or outside the centrifuge (10). Thereby, combustible temperature control media can be used without safety concerns for controlling the temperature of centrifuges (10).

Claims

1. A centrifuge (10), comprising: a centrifuge container (16) in which a centrifuge rotor (20, 20′) can be accommodated; a motor (18) for driving the centrifuge rotor (20, 20′); temperature control means (24, 42, 44) for controlling the temperature of the centrifuge rotor (20, 20′); and a housing (12) in which the centrifuge container (16), the centrifuge rotor (20, 20′), the temperature control means (24, 42, 44) and the motor (18) are accommodated, wherein the temperature control means (24, 42, 44) comprise a combustible temperature control medium that is guided in a temperature control medium line (24), and wherein the centrifuge (10) comprises a protective gas and is adapted to release the protective gas in the event of a crash of the centrifuge rotor (20, 20′), and wherein the protective gas is guided in a protective gas line (26), which extends around the centrifuge container (16) with one or several windings (36), and wherein the protective gas line (26) and the temperature control medium line (24) are connected to one another at least in some areas.

2. The centrifuge (10) according to claim 1, wherein the protective gas is an inert gas.

3. The centrifuge (10) according to claim 1, wherein the protective gas is at least one gas selected from the group consisting of argon, helium, carbon dioxide, krypton, neon, nitrogen and xenon.

4. The centrifuge (10) according to claim 1, wherein the protective gas line (26) is connected to a protective gas source (34).

5. The centrifuge (10) according to claim 4, wherein the protective gas source (34) contains the protective gas under a pressure above atmospheric pressure.

6. The centrifuge (10) according to claim 4, further comprising a throttle element arranged between the protective gas line (26) and the protective gas source (34).

7. The centrifuge (10) according to claim 4, wherein at least two sections (28, 30) of the protective line (26) are connected in parallel with the protective gas source (34).

8. The centrifuge (10) according to claim 1, wherein the protective gas line (26) is arranged at least in areas (36) with respect to the centrifuge container (16) next to and/or below the temperature control medium line (50).

9. The centrifuge (10) according to claim 1, wherein the protective gas line (26) and the temperature control medium line (24) are soldered to one another at least over a quarter of their respective winding lengths.

10. The centrifuge (10) according to claim 1, wherein the protective gas line (26) has, at least in some areas, a smaller wall thickness than the temperature control medium line (24).

11. The centrifuge (10) according to claim 1, wherein the protective gas line (26) and/or the temperature control medium line (24) are arranged directly on the centrifuge container (16) or at least in some areas are at least a component of a wall of the centrifuge container (16).

12. The centrifuge according to claim 1, wherein a multi-channel system exists to an effect that there is at least one separate said winding for the protective gas and at least one separate winding for the combustible temperature control medium.

13. The centrifuge (10) according to claim 1, further comprising monitoring means (38) with regard to a condition of the protective gas which are adapted to limit a rotational speed of the centrifuge rotor (20, 20′) to a value that is not critical for a crash of the centrifuge rotor (20, 20′) if predetermined values far the condition of the protective gas are not reached.

14. The centrifuge (10) according to claim 13, wherein the monitoring means (38) measure a pressure and/or a quantity of protective gas.

15. The centrifuge (10) according to claim 1, further comprising a fan that, during operation of the centrifuge (10), continuously guides air from an interior of the housing into an environment of the centrifuge (10).

16. A method for preventing ignition of combustible tempering media in centrifuges (10) after a crash of a centrifuge rotor (20, 20′), wherein the centrifuge (10) comprises a centrifuge container (16), in which a centrifuge rotor (20, 20′) can be accommodated, a motor (18) for driving the centrifuge rotor (20, 20′), temperature control means (24, 42, 44) for controlling the temperature of the centrifuge rotor (20, 20′), a protective gas line (26) which extends around the centrifuge container (16) with one or several windings (36), and a housing (12) in which the centrifuge container (16), the centrifuge rotor (20, 20′), the temperature control means (24, 42, 44) and the motor (18) are accommodated, and wherein the temperature control means (24, 42, 44) comprises a combustible temperature control medium that is guided in a temperature control medium line (24), the method comprising: causing fragments of the centrifuge rotor to destroy the protective gas line (26) and thereby release a protective gas guided therein into the centrifuge in the event of a crash of the centrifuge rotor (20, 20′) before the fragments can destroy the temperature control medium line (24).

17. A centrifuge (10), comprising: a centrifuge container (16) in which a centrifuge rotor (20, 20′) can be accommodated; a motor (18) for driving the centrifuge rotor (20, 20′); temperature control means (24, 42, 44) for controlling the temperature of the centrifuge rotor (20, 20′); and a housing (12) in which the centrifuge container (16), the centrifuge rotor (20, 20′), the temperature control means (24, 42, 44) and the motor (18) are accommodated, wherein the temperature control means (24, 42, 44) comprise a combustible temperature control medium that is guided in a temperature control medium line (24), and wherein the centrifuge (10) comprises a protective gas and is adapted to release the protective gas in the event of a crash of the centrifuge rotor (20, 20′), and wherein the protective gas is guided in a protective gas line (26), which extends around the centrifuge container (16) with one or several windings (36), and wherein the protective gas line (26) is arranged such that, in case of a crash, fragments of the rotor break the protective gas line (26), thereby causing the release of the protective gas into the centrifuge, before the fragments can break the temperature control medium line (24).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a centrifuge in a perspective view.

(2) FIG. 2 shows the centrifuge according to FIG. 1 in a first partial sectional view from the right.

(3) FIG. 3 shows the centrifuge according to FIG. 1 in a second partial sectional view from the left.

(4) FIG. 4 is a detailed view of FIG. 2.

DETAILED DESCRIPTION

(5) In FIGS. 1 to 4, the centrifuge 10 is shown purely schematically in various views.

(6) As shown, centrifuge 10 is designed as a laboratory centrifuge with a housing 12 with a cover 14 and an operating front 15. In the centrifuge container 16 of the centrifuge 10, a centrifuge rotor 20 is arranged on a drive shaft (not shown) of a centrifuge motor 18, which is designed as a swing-out rotor with centrifuge beakers 22.

(7) FIG. 2 shows that the centrifuge container 16 is surrounded by windings of a temperature control medium line 24 and windings of a protective gas line 26. (In FIG. 2, the centrifuge rotor 20′ is shown as a fixed angle rotor, in order to show that the present invention is independent of the exact type of the centrifuge rotor 20, 20′.)

(8) The two ends 28, 30 of the protective gas line 26 are brought together and are thus connected in parallel with the supply line 32 of a protective gas container 34, which contains a large quantity (for example, 1000 g) of carbon dioxide as a protective gas under a pressure above atmospheric pressure, for example a liquefied gas.

(9) In order to keep the line length from the protective gas container 34 to all possible points of the protective gas line 26 short, it may alternatively be provided that the individual windings 36 are connected to each other by means of a cross connection (not shown).

(10) A pressure switch 38 is arranged on the protective gas container 34, which pressure switch is connected to the control system (not shown) of the centrifuge 10 via a plug 40.

(11) The temperature control medium line 24 is connected in the usual manner to a compressor 42 (behind the ventilation slots 43 of the housing 12) and to a filter dryer 44.

(12) FIG. 2 also shows that the centrifuge 10 has a protective cover 48 next to a base plate 46, which is provided to prevent, in case of a crash of the centrifuge rotor 20′, its parts from being able escape from the centrifuge 10. Such protective cover 48 is therefore dimensioned and designed in terms of material in such a manner that sufficient crash energy can be absorbed. There is thermal insulation 49 between the protective cover 48 and the centrifuge container 16.

(13) The windings of the temperature control medium line 24, especially the winding parts 50, 52, form the evaporator. Thereby, the winding part 50 is located on the winding 36 of the protective gas line 26, and the winding part 52 is located next to the winding 36 of the protective gas line 26.

(14) The jacket surfaces of the windings 36 of the protective gas line 26 are externally connected to the winding parts 50 of the temperature control medium line 24 arranged above them by a soldered connection 54 (see FIG. 4), and the protective gas line 26 and the windings 52 of the temperature control medium line 24 arranged next to the protective gas line 26 are selectively soldered (not shown) to the centrifuge container 16, whereby the temperature control medium line 24 has sufficient heat conduction in all areas of its windings 50, 52 towards the centrifuge container 16, and thus the sufficient active indirect temperature control of the centrifuge rotor 20′ and the samples accommodated therein (not shown) is ensured. In doing so, the strength of the soldered connection is such that the connection to the temperature control medium line 24 tears in the area of the winding parts 50 before the temperature control medium line 24 itself tears here.

(15) Tubes in the form of elongated hollow bodies made of any material, preferably copper or aluminum, the length of which is usually much greater than the diameter of their cross-section, are used as the temperature control medium line 24 and the protective gas line 26.

(16) Thereby, it could be provided that the protective gas line 26 and the temperature control medium line 24 have different diameters and/or different wall thicknesses. A smaller wall thickness ensures that the protective gas line 26 is more likely to tear than the temperature control medium line 24. A smaller diameter would allow the protective gas line 26 to be arranged in the free space between the centrifuge container 16 and the windings 50 of the temperature control medium line 24.

(17) Alternatively, the windings 36, 50 of the protective gas line 26 and the temperature control medium line 24 could also run parallel next to each other, for example as a multi-channel solution (not shown), such that the temperature control medium line 24 would be arranged directly on the centrifuge container 16.

(18) In addition, it could also be provided that the temperature control medium line 24 and/or the protective gas line 26 at least partially form the centrifuge container 16 (not shown), which could reduce the required installation space.

(19) During operation, this design of the centrifuge 10 effectively prevents the ignition of the combustible temperature control medium even in the event of a crash of the centrifuge rotor 20, since, in the event of such a crash, components of the centrifuge rotor 20 damage the protective gas line 26 after the centrifuge container 16 has broken through, causing the protective gas to escape.

(20) Since the protective gas is under a pressure above atmospheric pressure, it will flow into the entire interior of the centrifuge 10 and displace the oxygen in the air therein and also dilute the possibly escaping temperature control agent. Due to the generated flow out of the centrifuge 10, the emerging mixture is additionally swirled and further diluted in the ambient air. This prevents the formation of an ignitable mixture.

(21) To monitor this safety function, there is the pressure monitor 38, which continuously monitors the quantity and/or pressure of the protective gas in the protective gas container 34 during the operation of the centrifuge 10. If the pressure monitor 38 detects a condition of the protective gas that is below previously defined values adapted to the specific centrifuge 10, it intervenes in the control system (not shown) of the centrifuge 10 in such a manner that either the centrifuge 10 does not start the centrifuge rotor 20, 20′ at all and, if necessary, issues an error message, or that the centrifuge rotor 20, 20′ can only be operated up to an uncritical maximum speed at which a crash cannot release any energy that would damage the temperature control medium line 24. This maximum speed is determined beforehand in test series.

(22) A throttle element (not shown) between the protective gas container 34 and the protective gas line 26 is used to adjust the outflow time, such that the ambient air and thus the atmospheric oxygen is displaced for a longer period of time, and the escaping temperature control medium is mixed and scattered with the escaping protective gas.

(23) By providing a fan (not shown) that runs continuously during the operation of the centrifuge 10 in accordance with DIN EN 378, risks of the formation of an ignitable mixture from a leakage in the temperature control medium line 24 are additionally avoided within the housing 12.

(24) It is clear from the above description that the present invention provides a centrifuge 10 with which combustible temperature control media can also be used without safety concerns within the framework of a temperature control process.

(25) Unless otherwise indicated, all features of the present invention may be freely combined. Moreover, the features described in the description of figures can be freely combined with the other features as features of the invention, unless otherwise indicated. Thereby, substantive features of the centrifuge can also be used within the framework of a method reformulated as method features, and method features within the framework of the centrifuge can be reformulated as features of the centrifuge.

LIST OF REFERENCE SIGNS

(26) 10 Centrifuge in accordance with the invention, laboratory centrifuge 12 Housing 14 Cover 15 Operating front 16 Centrifuge container 18 Centrifuge motor 20 Centrifuge rotor, swing-out rotor 20′ Centrifuge rotor, fixed angle rotor 22 Centrifuge beaker 24 Temperature control medium line 26 Protective gas line 28, 30 Ends of the protective gas line 26 32 Supply line of the protective gas container 34 34 Protective gas container 36 Windings of the protective gas line 26 38 Pressure switch 40 Plug 42 Compressor 44 Filter dryer 46 Base plate 48 Protective cover 49 Thermal insulation 50 Windings of the temperature control medium line 24, which are located above windings 36 of the protective gas line 26 52 Windings 52 of the temperature control medium line 24 arranged next to the protective gas line 26 54 Soldered connection between the windings 36 of the protective gas line 26 and the windings 50 of the temperature control medium line 24