Centrifuge, rotor for a centrifuge and drive head for a centrifuge

Abstract

The invention relates to a rotor (23) connected to a drive element (1) via a coupling device (37) actuated by centrifugal force. The coupling device (37) has an eccentric mass body (18) which is movably guided on the drive element (1). Furthermore, the coupling device (37) has a rotor recess (40) behind which the eccentric mass body (18) can be moved by the centrifugal force. According to the invention, the eccentric mass body (18) is guided along a guide track (41) on the drive element (1). Preferably, the eccentric mass body (18) has an eccentric mass ramp surface (21), and the rotor recess (40) has a rotor ramp surface (33). The ramp surfaces (21, 33) are inclined at a ramp angle relative to an axis of rotation (39) of the rotor (23) that is less than 45°.

Description

[0001] The invention relates to a centrifuge, in particular a laboratory centrifuge. Centrifuges of the present type are used, for example, in biotechnology, the pharmaceutical industry, medical technology, and environmental analysis. Such a centrifuge centrifuges a product, in particular a container or vessel with a sample or substance arranged therein, or a plurality of such products, at speeds that may exceed 3,000 rpm, for example, more than 15,000 rpm. As a result of centrifugation, accelerations acting on the product are to be generated, which may, for example, exceed 15,000 xg (in particular, more than 16,000 xg, more than 20,000 xg, up to more than 60,000 xg). Centrifugation is intended to break down a mixture of substances formed by the sample or substance into components of different densities.Depending on the chemical and / or physical properties of the substance mixture, targeted control of the pressure and / or temperature conditions can also be carried out during centrifugation. To name just a few examples, a laboratory centrifuge can be used in connection with a polymerase chain reaction (PCR), hematocrit determination, cytological examinations, or the centrifugation of microtiters, blood bags, petroleum containers, blood vessels, etc. In the centrifuge, at least one product is arranged in a rotor or the at least one product is held on a rotor. The rotor can be designed, for example, as a so-called fixed-angle rotor or a swing-out rotor.

[0002] Furthermore, the invention relates to a rotor for a centrifuge and a drive head for a centrifuge. STATE OF THE ART

[0003] In order to set the rotor with the products into the rotation required for centrifugation, an output element of the rotor is coupled via a coupling device to a drive element of the laboratory centrifuge, which is usually formed by a drive shaft and driven by a motor. The coupling device serves to axially secure the output element to the drive element and thus the rotor to the driven drive shaft of the motor. It is possible that the coupling device also serves to positively transmit the drive torque from the drive shaft to the rotor. It is also possible for the drive torque to be transmitted via a frictional connection of coupling surfaces, whereby the contact force of the coupling surfaces can depend on the dead weight of the rotor and a force component of a coupling force.High demands must be placed on the operational reliability of the coupling device, particularly due to the aerodynamic effects resulting from high speeds, the large centrifugal forces, gyroscopic effects in the event of a visible impact on the laboratory centrifuge and the like.

[0004] During proper laboratory operation of a laboratory centrifuge, repeated assembly and disassembly of the rotor is necessary in order to successively examine a large number of vessels containing substances to be centrifuged using the same rotor or different rotors. It has been found that the use of manually operated clutches can be disadvantageous due to the manual effort and the associated time required, as well as in terms of operational reliability. For this reason, centrifugal force-operated clutches are used, in which the output element of the rotor is simply placed on the motor-driven drive element of the laboratory centrifuge.While initially only a frictional connection between the drive element and the output element due to the rotor's own weight ensures the coupling between the drive element and the output element, as the rotor speed increases, the coupling force of the centrifugally actuated clutch device increases due to centrifugal force. The higher the speed, the greater the clutch force generated by the centrifugal force. It is also possible to use a manually actuated clutch device in addition to such a centrifugally actuated clutch device.

[0005] Design variants are known in which an eccentric mass body, which is subjected to centrifugal force and creates the coupling force, is mounted on the rotor. The eccentric mass body then creates a locking connection with a locking groove of a drive shaft. The problem here is that the centrifugal force acts radially outwards, whereas locking requires radially inwards with the locking groove of the drive shaft. For this reason, locking levers are used that can be pivoted about a pivot axis oriented tangentially to the circumferential direction. The center of gravity of the locking lever lies radially outwards from the pivot axis, so that pivoting due to the centrifugal force results in the radially inner lever part of the locking lever being subjected to radial inwards.Coupling devices in which a pivotable locking lever is held on the rotor are known, for example, from the documents US 2013 / 0237399 A1, US 2013 / 0203581 A1, WO 2012 / 059151 A1, US 2014 / 0329658 A1 and WO 2011 / 001729 A1.

[0006] According to EP 3 012 027 B1, eccentric masses are also mounted on the rotor. In this case, however, they are designed as rolling or sliding bodies. A centrifugal force acting on the eccentric masses is deflected via a guideway with additional transmission bodies, so that a radially inwardly directed coupling force can be generated for locking with a drive shaft.

[0007] EP 2 321 058 B1 proposes another embodiment of a coupling device in which locking levers are mounted on a drive head so as to be pivotable about a pivot axis oriented parallel to a rotational axis of the drive shaft. If the locking levers are subjected to a radially outwardly oriented coupling force due to centrifugal force, they pivot outward. The locking levers come into contact with corresponding ramp surfaces of a sleeve of the rotor via ramp surfaces. The ramp surfaces are inclined at an angle of 75° to 90° relative to the rotational axis of the drive shaft. At the ramp surfaces, the locking levers generate an axial force with which the sleeve of the rotor is clamped between the ramp surfaces of the locking levers and a truncated conical surface of the drive head having an oppositely oriented opening angle. In this way, the rotor is axially fixed on the drive head.The drive head is bolted to one end of the drive shaft. The pivot pins, via which the locking levers are pivotably mounted on the drive head, protrude from the drive head and fit into corresponding holes in the rotor, allowing a positive transmission of the drive torque between the drive head and the rotor.

[0008] US Pat. No. 6,063,018 A discloses a laboratory centrifuge in which a drive element with a frustoconical drive surface is driven by a motor. The rotor has a corresponding frustoconical internal friction surface, with which the rotor is pressed against the frustoconical friction surface of the drive element due to its own weight. When the drive element begins to move, the frictional force between the friction surfaces transfers the rotary motion to the rotor. Distributed around the circumference and opposite one another in a transverse plane of the drive element, two clutch levers are mounted so that they can pivot outward due to centrifugal force. Clutch surfaces of the clutch levers, inclined relative to the transverse direction of the drive element, are pressed against corresponding clutch surfaces of the rotor due to centrifugal force.In this way, a positive axial locking of the rotor on the drive element is achieved. Due to the inclination of the clutch surfaces, the centrifugal force leads to a speed-dependent axial force component, which increasingly increases the contact pressure of the frustoconical friction surfaces against each other with increasing speed. After the rotor is placed on the drive element, springs press the clutch levers radially outward, locking the rotor even without rotation. Unlocking the rotor requires manual operation of a button, which causes the clutch levers to move radially inward, thus unlocking the clutch mechanism.

[0009] Further prior art is known in particular from DE 102012011 531 A1, JP 2008-126130 A, DE 10 2021 121 259 A1 and JP S56164040 U. OBJECT OF THE INVENTION

[0010] The invention is based on the object of proposing a centrifuge with an alternative centrifugal force-operated coupling device for a rotationally fixed and axially secured coupling of a rotor with a drive element of a drive unit, which is particularly suitable with regard to the safety of the coupling device during operation of the centrifuge and / or simple, yet reliable operation and / or the complexity of the required components and / or the costs and / or the robustness and / or operability without manual operating elements is improved. Furthermore, the invention is based on the object of proposing a correspondingly improved rotor for a centrifuge and a correspondingly improved drive head for a centrifuge. SOLUTION

[0011] The object of the invention is achieved according to the invention with the features of the independent patent claims. Further preferred embodiments of the invention can be found in the dependent patent claims. DESCRIPTION OF THE INVENTION

[0012] The invention proposes a centrifuge, in particular a laboratory centrifuge, in which a rotor, in particular a fixed-angle rotor, is connected to a drive element via a centrifugal force-actuated coupling device. In the coupling device according to the invention, the eccentric mass body is not movably guided on the rotor. Rather, the eccentric mass body of the coupling device is movably guided on the drive element. The rotor preferably has a rotor recess. As a result of the centrifugal force, the eccentric mass body can be moved behind the rotor recess, thereby bringing about the coupling effect. Alternatively or cumulatively, it is possible for the eccentric mass body (in particular to bring about the coupling effect and / or an axial contact force) to be moved by the centrifugal force against a ramp surface, in particular a rotor recess ramp surface or rotor ramp surface.

[0013] According to the invention, the eccentric mass body is not pivotably mounted about a pivot axis, but is guided along a guideway on the drive element. The guideway can provide guidance along a curved degree of freedom, with at least one component of the guideway being oriented in the radial direction. The eccentric mass body can thus be moved along the guideway by means of centrifugal force. The eccentric mass body preferably has a translational degree of freedom relative to the drive element, which can be oriented in the radial direction or at a fixed acute angle to the radial direction.

[0014] The inventive design is based in particular on the realization that locking levers mounted on the drive element, as known from the prior art, require a large installation space and are not optimal in terms of mass utilization, since locking lever parts arranged on either side of a pivot axis generate opposing pivoting moments, so that only a difference in the pivoting moments can be utilized for the locking effect. In addition, the rotatable mounting of a locking lever requires a bearing by means of a plain or roller bearing, which can place stringent manufacturing demands, requires additional components such as rolling elements or sliding sleeves, and tighter manufacturing tolerances in the bearing surfaces, and is susceptible to wear.However, in the context of the invention, in extreme cases, a block-like eccentric mass body can be used, which is guided exclusively by flat sliding contacts with a guideway. Such an eccentric mass body can be manufactured simply and cost-effectively and is subject to low wear even during continuous operation at high speeds. The contact surface of the eccentric mass body with a guideway allows surface pressures to be kept low, thus design-specifically predetermining and reducing mechanical stresses. Furthermore, compared to the aforementioned locking lever, the entire mass of the eccentric mass body can be used to generate the centrifugal force and thus the coupling force.

[0015] It is possible that the eccentric mass body, after moving behind the rotor recess, ensures a positive locking or securing action due to centrifugal force. According to one proposal of the invention, the eccentric mass body has an eccentric mass body ramp surface, while the rotor or a rotor recess has a rotor ramp surface (hereinafter also collectively referred to as "ramp surface"). In a semi-longitudinal section, the ramp surfaces are inclined with respect to the rotor's rotational axis at a ramp surface angle of less than 45° (in particular, less than 30°, less than 25°, or less than 20°).This embodiment of the invention is based on the finding that, for centrifuges known from the prior art, releasing the locking lever after the centrifuge has finished operating requires separate measures such as pressing a release button, or the locking lever must be actuated by a spring. When the centrifuging effect ceases, the locking lever returns to its initial position, in which position the rotor can be removed from the drive element. However, if the small ramp surface angle previously proposed according to the invention is selected, a return movement of the eccentric mass body can be induced solely by applying removal forces to the rotor.The reason for this is that the removal force acting on the ramp surface is converted via the ramp surface angle into a restoring force acting on the eccentric mass body, which supports or even solely causes a return movement to the initial position corresponding to the released coupling device. Preferably, the ramp surface angle is selected such that no self-locking occurs in the area of ​​contact between the ramp surfaces.

[0016] Within the scope of the invention, the drive element can be designed in any desired manner. It is entirely possible for the drive element to be formed directly from the drive shaft of the drive motor. In a particular proposal of the invention, the drive element is a (single- or multi-part) drive head that is non-rotatably mounted on the drive shaft of the drive motor. For example, it is possible for the drive head to be connected to the drive shaft via a known shaft-hub connection that transmits drive torque. Securing can be achieved via a fastening screw screwed to the end face of the drive shaft.

[0017] Within the scope of the invention, there are numerous possibilities for holding and guiding the eccentric mass body on the drive element, as long as guidance occurs along a straight or curved guide path. A particularly simple guidance of the eccentric mass body can consist of ensuring guidance by means of an engagement of a guide projection (in particular a bolt or pin) in a groove or elongated hole. For example, the eccentric mass body can have the groove or elongated hole, while the drive element then has the guide projection, bolt, or pin (although a reversed arrangement of the elongated hole or groove on the one hand and the guide projection on the other is also possible).

[0018] Any number of eccentric masses can be used within the scope of the invention, whereby the eccentric masses can have identical or different geometries and can be arranged at identical or different radii. Preferably, several eccentric masses are arranged and guided evenly in the circumferential direction on the drive element. A particularly compact but efficient design of the centrifuge results if exactly three eccentric masses are guided on the drive element, evenly distributed over the circumference. The three eccentric masses ensure stable support between the rotor and the drive element in the required directions. Alternatively, the three eccentric masses distributed in the circumferential direction can have a relatively large mass, which can bring about a high securing effect.

[0019] Within the scope of the invention, it is entirely possible for the drive torque to be transmitted between the drive element and the rotor via a frictional connection, wherein the frictional connection is preferably created in the region of adjacent transverse surfaces, ramp surfaces, or conical surfaces. The contact force causing the friction can be caused by the weight of the rotor and / or at least one component of the centrifugal force or coupling force. However, according to one proposal of the invention, the drive element additionally has a positive-locking element. The positive-locking element of the drive element then interacts with a counter-positive-locking element of the rotor for the positive-locking transmission of the drive torque.There are many different options for designing the form-locking element and the counter-form-locking element, and those known from the prior art can also be used within the scope of the invention. Preferably, the form-locking element and the counter-form-locking element have a non-circular cross-section that transmits the drive torque. For example, the form-locking element and the counter-form-locking element can be designed as a type of toothing with any tooth geometry or as a round cross-section with a superimposed shaft contour. Preferably, the form-locking element and the counter-form-locking element form insertion aids or bevels that enable the rotor to be attached to the drive element not only when the rotor is approached to the drive element in the exact angular position around the rotation axis.

[0020] It may well be desirable for the eccentric mass to be secured in the starting position, which corresponds to the released coupling device. Securing the eccentric mass in this way in the starting position can be advantageous in order to prevent the eccentric mass from undesirably leaving the starting position for a removed rotor, which could then make it impossible or difficult to attach a new rotor. Any desired locking devices or a spring (cf. the prior art mentioned at the beginning) can be used to secure the eccentric mass in the starting position, to name just a few examples which do not limit the invention. In one proposal of the invention, the eccentric mass is secured in a starting position by means of a magnet. For example,the drive element and the eccentric mass body have (permanent) magnets whose mutually attractive poles are aligned and arranged closely next to each other in the starting position, while their distance increases when leaving the starting position. In addition to the securing effect in the starting position, a magnet can also contribute to the eccentric mass body returning to the starting position after centrifugation has ended. The design of the magnet and the securing effect brought about by the magnet is such that the securing is automatically released when the drive element with the eccentric mass body is rotated at a threshold speed up to which the securing effect is desired. In this case, the speed causes a centrifugal force acting on the eccentric mass body, which can overcome the magnetic securing force.

[0021] According to a further proposal of the invention, the drive element has a drive element conical surface. The rotor has a rotor conical surface. The drive element conical surface and the rotor conical surface are inclined opposite to the eccentric mass body ramp surface and the rotor ramp surface, resulting in the rotor with the rotor conical surface and rotor ramp surface being "trapped" between the drive element conical surface and the eccentric mass body ramp surface. The opposite angles of the drive element conical surface and the rotor conical surface, on the one hand, and the eccentric mass body ramp surface and the rotor ramp surface, on the other hand, can be the same or different.

[0022] Alternatively, it is possible for the drive element conical surface and the eccentric mass body ramp surface to be "trapped" between the rotor conical surface and the rotor ramp surface. In this configuration, the centrifugal force and the resulting coupling force generate a contact force against the aforementioned conical surfaces and ramp surfaces, resulting in axial clamping of the rotor against the drive element.

[0023] While a different arrangement is certainly possible, the invention proposes, as a further proposal, that the drive element conical surface and the rotor conical surface be arranged on the side facing away from the drive (i.e., for a vertical arrangement of the rotor axis with the drive located below, above the eccentric mass body ramp surface and the rotor ramp surface). This enables a particularly compact, reliable, and durable design of the resulting shaft-hub connection for holding the rotor and for the coupling device.

[0024] There are also numerous possibilities within the scope of the invention for the arrangement of the form-locking element and the counter-form-locking element in the axial direction and relative to the conical surfaces and ramp surfaces. For one proposal of the invention, the form-locking element and the counter-form-locking element are arranged between, on the one hand, the drive element conical surface and the rotor conical surface, and, on the other hand, the eccentric mass body ramp surface and the rotor ramp surface. This configuration preferably displaces the form-locking element and the counter-form-locking element away from the end region of the drive element arranged inside the rotor, which can result in a particularly rigid and reliable transmission of the drive torque between the form-locking element and the counter-form-locking element being possible and, under certain circumstances, also more material being available in the region of the drive element for the design and support of the form-locking element.

[0025] The rotor can form the described functional surfaces for interaction with the drive element in any desired manner, whereby the rotor can comprise any number of components for this purpose. According to one proposal of the invention, the rotor has a (single-part or multi-part) insert sleeve. The drive element can then enter this insert sleeve and bring about at least some of the required interactions and provide the functional surfaces. For this purpose, the insert sleeve can form the rotor ramp surface and / or the counter-form-locking element. Optionally, it is then also possible for the insert sleeve to form the rotor conical surface.

[0026] There are also many possibilities for the design of the drive element, in particular the drive head, whereby the drive element is preferably designed in several parts. In one proposal of the invention, the drive element has a base body. This base body preferably then forms the drive element conical surface. Furthermore, the drive element has a cover body which is connected to the base body. An eccentric mass body receiving space is then formed between the base body and the cover body. The eccentric mass body can then be movably arranged in the eccentric mass body receiving space. In the eccentric mass body receiving space, the eccentric mass body is then also guided along the guide track. This guidance is preferably provided by a contact surface of the eccentric mass body with the base body and / or the cover body.Such a contact surface can have a surface normal oriented parallel to the rotor's rotational axis. Furthermore, it is possible for the base body and / or the cover body to have radially oriented ribs, via which (possibly in addition to the guide projection, groove, or slot) the eccentric mass body can be guided. In this case, for example, a surface normal of a contact surface of the eccentric mass body with such a rib can be oriented tangentially to the circumferential direction.

[0027] There are many possible designs for the (single- or multi-part) eccentric mass body. For one proposal of the invention, the eccentric mass body is designed (at least roughly) as a (single- or multi-part) circular ring segment. A radially outer end face of the circular ring segment can then form the eccentric mass body ramp surface. For example, it is possible for the centers of the inner and outer surfaces of the circular ring segment to be offset from one another in the radial direction. For example, it is possible for the centers to be offset from one another by the displacement path of the eccentric mass body, which can result in a particularly compact design.

[0028] If several eccentric mass bodies designed as circular ring segments are used, which have the same shape and the same radii, the sum of the extensions of the circular ring segments is preferably greater than 300°, greater than 320° or greater than 330°, which can ensure a very compact design despite the high mass of the eccentric mass bodies.

[0029] In addition to the explained connection and securing measures for attaching the rotor to the drive head, any desired further connection and / or securing measures can be used. According to one proposal of the invention, the eccentric mass body has a locking element that interacts with a groove or undercut of the rotor. This interaction, in particular an engagement of the locking element in the groove or behind the undercut, ensures positive locking. Unlocking can occur, for example, at standstill due to the magnetic force of the magnets, by means of a manually operated unlocking mechanism, or via a spring.

[0030] A further solution to the problem underlying the invention is a rotor which is intended for a centrifuge as previously explained and is designed accordingly. To name just a few examples, the rotor can have a rotor recess behind which the eccentric mass body can be moved as a result of centrifugal force. The rotor recess can have a rotor ramp surface which, in a semi-longitudinal section, is inclined at a ramp surface angle to a rotational axis of the rotor that is less than 45° (in particular less than 30°, less than 25°, or less than 20°). The rotor can have a counter positive locking element which interacts with the positive locking element of the drive element for the positive transmission of the drive torque. The rotor can have a rotor conical surface, whereby the rotor conical surface can be inclined opposite to the rotor ramp surface. It is possible for the rotor ramp surface to be arranged further outwards, i.e. upstream in the direction of the drive, than the rotor conical surface.The counter-form-locking element of the rotor can be arranged between the rotor conical surface and the rotor ramp surface. The rotor can have an insert sleeve that forms the rotor ramp surface and / or the counter-form-locking element and / or the rotor conical surface.

[0031] A further solution to the problem underlying the invention is provided by a drive head intended for a centrifuge as previously explained and designed accordingly. The drive head has a centrifugal force-actuated coupling device comprising an eccentric mass body movably guided on the drive head. The eccentric mass body is guided along a guide track on the drive head, preferably with a translational degree of freedom.

[0032] Advantageous further developments of the invention emerge from the patent claims, the description and the drawings.

[0033] The advantages of features and combinations of several features mentioned in the description are merely exemplary and can be effective alternatively or cumulatively, without the advantages necessarily having to be achieved by embodiments according to the invention.

[0034] With regard to the disclosure content – ​​not the scope of protection – of the original application documents and the patent, the following applies: Further features can be found in the drawings – in particular the illustrated geometries and the relative dimensions of several components to one another, as well as their relative arrangement and operative connection. The combination of features of different embodiments of the invention or features of different patent claims is also possible, deviating from the chosen references of the patent claims, and is hereby encouraged. This also applies to features that are illustrated in separate drawings or mentioned in their description. These features can also be combined with features of different patent claims.Likewise, features listed in the patent claims may be omitted for further embodiments of the invention, but this does not apply to the independent patent claims of the granted patent.

[0035] The number of features mentioned in the patent claims and the description is to be understood as meaning that exactly this number or a greater number than the stated number is present, without the need for the explicit use of the adverb "at least." Thus, for example, if reference is made to an eccentric mass or magnet, this is to be understood as meaning that exactly one eccentric mass or magnet, two eccentric masses or magnets, or more eccentric masses or magnets are present. The features mentioned in the patent claims may be supplemented by further features or may be the only features present in the subject matter of the respective patent claim.

[0036] The reference signs contained in the patent claims do not represent a limitation of the scope of the subject-matter protected by the patent claims. They serve solely to make the patent claims easier to understand. BRIEF DESCRIPTION OF THE CHARACTERS

[0037] In the following, the invention is further explained and described with reference to preferred embodiments shown in the figures. Fig. 1 shows a drive element of a laboratory centrifuge designed as a drive head in a spatial exploded view. Fig. 2 shows a rotor with drive head arranged therein according to Fig. 1 in a spatial semi-longitudinal section, with the coupling device released. Fig. 3 shows a longitudinal section through the rotor with drive head according to Fig. 2 . Fig. 4 shows a longitudinal section through the drive head according to Fig. 1 , wherein the coupling device is in the released initial position. Fig. 5shows the drive head according to Fig. 1 and 4 in the released starting position in a spatial view. Fig. 6 to 9 show the Fig. 2 to 5 corresponding representations, although here the coupling device is in the coupled position. Fig. 10 shows a further embodiment of a drive head with its approach to a rotor in a longitudinal section. Fig. 11 shows the rotor and the drive head according to Fig. 10 in a spatial semi-longitudinal section. Figs. 12 and 13 show views according to Fig. 10 and 11 , but here the coupling device has left the released initial position and has assumed a coupled position. Fig. 14 shows a further embodiment of a drive head in the coupling area with a rotor in a detail of a semi-longitudinal section. FIGURE DESCRIPTION

[0038] In the following description of the figures, some components or features are identified by the same reference numbers, whereby these can then be distinguished from one another by the additional letters a, b,... In this case, reference can also be made to the component or feature without the additional letter, which can then refer to one component or feature, several components or features, or all components or features.

[0039] Fig. 1 shows a drive element 1, which is designed as a drive head 2. The drive head 2 can be non-rotatably attached to a drive shaft of a centrifuge drive motor (not shown here). The drive head 2 has a cover body 3 and a base body 4.

[0040] The base body 4 forms a drive element conical surface 5 in the lower end region, which widens from a cylindrical guide surface 6. Although this is not necessarily the case, the base body 4 integrally forms a star body 7. The star body 7 has radially oriented ribs 8 that extend from a star sleeve 9.

[0041] The cover body 3 has a circular disk 10, which is placed on top of the star body 7 and secured to the star body 7 by means of screws 11a, 11b, 11c. The screws 11a, 11b, 11c are screwed through bores 12a, 12b, 12c of the circular disk 10 to threaded bores 13a, 13b, 13c in the area of ​​the ribs 8a, 8b, 8c. Between the cover body 3 and the base body, three eccentric mass body receiving spaces 14a, 14b, 14c are formed, which are open radially outward, delimited radially inward by the star sleeve 9, and delimited in the circumferential direction by the ribs 8a, 8b, 8c.

[0042] The cover body 3 has a form-locking element 15 on the outer side.

[0043] According to Fig. 1 the form-locking element 15 has a lateral surface 16 with a star-shaped cross-section or a toothing of any shape, a polygon or similar.

[0044] The drive head 2 has a recess 17 extending in the direction of a rotation axis 39. In Fig. 2 It can be seen that this recess 17 has a truncated conical surface in the lower end area, which continues into a cylindrical bore. The recess 17 serves to attach the drive head 2 to a drive shaft of the laboratory centrifuge, which is not described in detail here.

[0045] An eccentric mass body 18a, 18b, 18c is arranged in each of the eccentric mass body receiving spaces 14a, 14b, 14c. The eccentric mass bodies 18 are each designed as circular ring segments 19a, 19b, 19c. The radially inner end face of the circular ring segments 19 is preferably designed in the shape of a cylindrical segment. The end faces of the circular ring segments 19 in the circumferential direction are oriented radially to the rotation axis 39. The lower and upper sides of the circular ring segments 19 are oriented parallel to one another with a surface normal that is oriented parallel to the rotation axis 39. The outer circumferential surface 20 of the circular ring segments 19 is designed in the shape of a truncated cone segment and forms an eccentric mass body ramp surface 21 that is inclined relative to a rotation axis 39 with a ramp surface angle 22 that is preferably 15° + / - 5°.

[0046] Two guide projections 24, 25 each extend into the eccentric mass body receiving spaces 14. In the illustrated embodiment, these guide projections are designed as guide pins 26, 27 oriented parallel to the rotation axis 39. The guide pins 26, 27 enter radially oriented grooves or elongated holes on the underside of the eccentric mass body 18, whose longitudinal axis is preferably oriented radially to the rotation axis 39. The engagement of the guide pins 26, 27 in the grooves or elongated holes ensures that the eccentric mass body 18 is guided in such a way that the movement of the eccentric mass body occurs in the radial direction relative to the rotation axis 39.

[0047] Furthermore, in the area of ​​the eccentric mass body receiving spaces 14, a magnet 28 designed as a permanent magnet is arranged, the radially outer pole of which is preferably arranged flush with the sliding surface between the eccentric mass body 18 and the drive head 2.

[0048] When the cover body 3 is mounted with the base body 4, the eccentric mass bodies 18 are trapped in the eccentric mass body receiving spaces 14 between the cover body 3 and the contact surface on the base body 4 in the direction of the rotation axis 39, preventing the guide pins 26, 27 from escaping from the grooves or elongated holes. The maximum radial outward movement path of the eccentric mass bodies 18 is determined by the length of the grooves or elongated holes.

[0049] Fig. 2 shows a partial spatial section of a rotor 23 with a drive head 2 mounted therein. A base body 29 of the rotor 23 has a continuous recess 30 oriented coaxially to the rotational axis 39. The recess 30 has the following sections in the direction of the rotational axis 39, which are directly connected to one another: a frustoconical rotor cone surface 31, a cylindrical guide surface 32, a rotor recess ramp surface 33 inclined with the ramp surface angle 22 relative to the rotation axis 39, which is preferably formed in the region of a rotor recess 40 of the rotor 23, which can form an undercut, for example, a cylindrical intermediate section 34, in the region of which the cover body 3 is arranged and a section with a reduced diameter, in which the recess 30 forms the counter-form-locking element 35.

[0050] The counter-form-locking element 35 has an inner surface whose cross-section corresponds to the cross-section of the outer surface 16 of the form-locking element 15, so that the form-locking element 15 can be arranged in a precisely fitting and form-fitting manner for transmitting a drive torque in the counter-form-locking element 35.

[0051] Fig. 2It can be seen that on the side facing the magnet 28, a magnet 36 designed as a permanent magnet is arranged in a bore of the eccentric mass body 18.

[0052] In Fig. 2 The eccentric mass bodies 18 are in their initial position. In this initial position, the magnet 36 of the eccentric mass bodies 18 is arranged with the opposite pole adjacent to and aligned with the pole of the magnet 28, so that the initial position is secured by the magnetic force between the magnets 28, 36.

[0053] When the drive motor is actuated, the drive movement is transmitted to the drive head 2 via the shaft-hub connection between the drive shaft and the drive head 2, which in turn is transmitted to the rotor 23 via the positive locking between the positive locking element 15 and the counter-positive locking element 35. If the centrifugal force acting on the eccentric mass bodies 18 overcomes the magnetic securing force, the eccentric mass bodies 18 slide radially outwards in the eccentric mass body receiving spaces 14 until the eccentric mass bodies 18 come into contact with the rotor ramp surfaces 33 with the eccentric mass body ramp surfaces 21. The centrifugal forces acting in the contact surface thus generated are converted into an axial force due to the ramp surface angle 22, which presses the base body 29 of the rotor 23 with the rotor conical surface 31 against the drive element conical surface 5.

[0054] The interaction of the eccentric mass bodies 18 with the eccentric mass body ramp surfaces 21 with the rotor ramp surfaces 33 of the base body 29 of the rotor forms a coupling device 37, via which a reliable connection between the rotor 23 and the drive head is ensured as long as a sufficient centrifugal force is generated on the eccentric mass bodies 18 as a result of the rotation.

[0055] Fig. 3 , 4 and 5 show the drive head 2 in a state of the coupling device 37 in which the eccentric mass bodies 18 are in the initial position. Fig. 6 to 9an operating state of the coupling device 37 in which the eccentric mass bodies 18 are in the coupled position or secured position. If, after centrifugation has ended, removal of the rotor 23 from the drive head 2 is desired, the eccentric mass bodies 18 may well still be in the secured position. However, if removal forces oriented parallel to the axis of rotation 39 are then applied to the rotor 23, these removal forces generate a force component oriented radially inward on the eccentric mass body ramp surfaces 21 due to the ramp surface angle 22, whereby the eccentric mass bodies 18 can slide radially inward until they release the removal of the rotor 23 and the starting position of the eccentric mass bodies 18 can be secured by the interaction between the magnets 28, 36.

[0056] In the Fig. 1 to 9In the illustrated embodiment, guidance can be ensured by precisely fitting cylindrical contact surfaces between the guide surfaces 6, 32. It is also possible that in these areas, no guidance is provided via contact surfaces, but rather a certain amount of play is present. In this case, guidance can be provided by means of guide surfaces 42, 43, which are formed by the outer surface of the circular disk 10 and an inner surface of the rotor 23.

[0057] For the Fig. 1 to 9 In the illustrated embodiment, for a rotor 23 mounted on the drive head 2, the form-locking element 15 and the counter-form-locking element 35, the eccentric mass body ramp surface 21 and the rotor ramp surface 33 and the drive element conical surface 5 and the rotor conical surface 31 are arranged in this axial order, with the form-locking element 15 being arranged furthest in the rotor 23. In Fig. 10 to 13Another embodiment is shown in which the drive element conical surface 5 and the rotor conical surface 31, the form-locking element 15 and the counter-form-locking element 35, and the eccentric mass body ramp surface 21 and the rotor ramp surface 33 are arranged in this axial order, wherein in this case the drive element conical surface 5 and the rotor conical surface 21 are arranged furthest inside the rotor 23. This embodiment allows, for example, the form-locking element 15 and the counter-form-locking element 35 to have a larger diameter, thus ensuring improved transmission of the drive torque.Furthermore, in this way, the arrangement of the form-locking element 15 and the counter-form-locking element 35 and / or the eccentric mass body ramp surface 21 and the rotor ramp surface 33 can also be achieved in a material region of the rotor 23 that has a smaller axial distance from the drive, for rigid support and a reduced lever arm of any forces. Alternatively or cumulatively, this configuration may allow for more material to be made available in the area of ​​these elements, which may result in improved strength.

[0058] For the Fig. 1 to 9 In the embodiment shown, the functional surfaces with which the rotor 23 interacts with the drive head 2 were formed integrally from the base body 29. However, according to the embodiment in Fig. 10 to 13These functional surfaces are at least partially formed by an insert sleeve 38, which can be inserted into the base body 29 and screwed thereto. For the illustrated embodiment, the insert sleeve 38 forms both the rotor ramp surface 33 and the counter-form-locking element 35, while the rotor conical surface 31 is formed by the base body 29.

[0059] Preferably, the eccentric mass body ramp surfaces 21 are rounded in the area of ​​the axial edges.

[0060] The coupling device 37 can be released, in particular without tools, by applying removal forces to the rotor 23. It is possible that, after the centrifuge has been operated and the rotor 23 has come to a standstill, the magnets 28, 36 automatically return the eccentric mass bodies 18 to the unlocked starting position. However, it is also possible that, alternatively or cumulatively, the removal forces manually applied by the user to the rotor 23 are converted via the angle of inclination of the eccentric mass body ramp surfaces 21 into a force that moves the eccentric mass bodies 18 back to the unlocked starting position.

[0061] Preferably, the eccentric mass bodies 18 are made of stainless steel, whereby it is possible that the base body 29 of the rotor 23 and / or the insert sleeve 38 is then made of aluminum or stainless steel.

[0062] According to the invention, the eccentric mass bodies 18 are guided by a guide track 41. The guide track 41 can be provided alternatively or cumulatively as follows: It is possible for the guide track 41 to be provided by guiding the guide projections 24, 25 in the grooves or elongated holes of the eccentric mass body 18. In this way, guidance of the eccentric mass body 18 in the radial direction is preferably ensured and a radially outer or radially inner stop is provided for the movement of the eccentric mass body 18. It is possible for the guide track 41 to be provided by guiding the eccentric mass body 18 between the underside of the cover body 3 and the top side of the base body 4. This guidance ensures, in particular, that no tilting of the eccentric mass body 18 can occur and / or no movement of the eccentric mass body 18 can occur in the axial direction.It is also possible that the guideway 41 is ensured by contact surfaces between the end faces of the eccentric mass bodies 18 in the circumferential direction and the side surfaces of the ribs 8 (this is not the case for the illustrated embodiment).

[0063] Deviating from the illustrated embodiments, the counter-form-locking element 35 can also be arranged axially on the outside of the rotor 23, whereby the form-locking element 15 is then arranged in the lower end region of the base body 4.

[0064] Fig. 14shows an embodiment in which a connection between the drive head 2 and the rotor 23 is not exclusively established and secured by the fact that the rotor 23 is clamped with the rotor conical surface 31 and the rotor ramp surface 33 between the eccentric mass body ramp surface 21 and the output element conical surface 5. Rather, an additional connection and securing is achieved here by the fact that the base body 29 of the rotor 23 has a groove or undercut 44. In this case, the eccentric mass body 18 has an outwardly oriented locking element 45. For the illustrated embodiment, the locking element 45 is directly adjacent to the eccentric mass body ramp surface 21, wherein the locking element 45 is arranged in the end region of the eccentric mass body ramp surface 21 that has the smaller distance from the axis of rotation 39.If the eccentric mass bodies 18 are moved radially outward as a result of centrifugation, the locking element 45 enters the groove or undercut 44, thus achieving a locked operating state. In the locked operating state, the locking element 45 and the groove or undercut 44 form a positive connection that blocks removal of the rotor 23 from the drive head 2 in a removal direction corresponding to the direction of the rotation axis 39.

[0065] The contact surfaces 46, 47 of the eccentric mass body 18 and the groove or undercut 44 can be of any shape. For example, the contact surfaces 46, 47 can be designed as circular ring segment surfaces whose surface normal corresponds to the rotation axis 39, or the contact surfaces 46, 47 can form any cone angle to the rotation axis 39. Fig. 14shows an embodiment in which the contact surface 47 of the groove or undercut 44 has a nose 48 which engages in a recess 49 of the contact surface 46.

[0066] Unlocking can occur when, with the deceleration of the rotor 23, the force of the magnets 28, 36 on the eccentric mass bodies 18 becomes greater than the radially outward friction force component acting in the contact surfaces and the remaining centrifugal force acting on the eccentric mass bodies 18. Alternatively or cumulatively, unlocking can occur, for example, via a spring or a manually operated unlocking device.

[0067] For the illustrated embodiment, the eccentric mass bodies 18 each form both the eccentric mass body ramp surfaces 21 and the locking elements 45. However, it is also possible for the first eccentric mass bodies to form the eccentric mass body ramp surfaces 21, while the locking elements 45 are formed by the second eccentric mass bodies. LIST OF REFERENCE SYMBOLS

[0068] 1 Drive element 2 Drive head 3 Cover body 4 Base body 5 Drive element conical surface 6 Guide surface 7 Star body 8 Rib 9 Star sleeve 10 Circular disc 11 Screws 12 Bore 13 Threaded holes 14 Eccentric mass body receiving space 15 Positive locking element 16 Shell surface 17 Recess 18 Eccentric mass body 19 Circular ring segment 20 Shell surface 21 Eccentric mass body ramp surface 22 Ramp surface angle 23 Rotor 24 Guide projection 25 Guide projection 26 Guide pin 27 Guide pin 28 Magnet 29 Base body 30 Recess 31 Rotor conical surface 32 Guide surface 33 Rotor ramp surface 34 Intermediate section 35 Counter positive locking element 36 Magnet 37Coupling device 38Insert sleeve 39Rotation axis 40Rotor recess 41Guideway 42Guide surface 43Guide surface 44Groove, undercut 45Locking element 46Contact surface 47Contact surface 48Nose 49Recess

Claims

1. Centrifuge with a rotor (23) which is connected to a drive element (1) via a centrifugal force-operated coupling device (37), wherein the coupling device (37) has an eccentric mass body (18) movably guided on the drive element (1), wherein the eccentric mass body (18) can preferably be moved by the centrifugal force behind a rotor recess (40) and / or against a rotor ramp surface (33), characterized in that the eccentric mass body (18) is guided along a guide track (41) on the drive element (1), preferably with a translational degree of freedom.

2. Centrifuge according to claim 1, characterized in thatthe eccentric mass body (18) has an eccentric mass body ramp surface (21) and the rotor (23) has a rotor ramp surface (33) which, in a semi-longitudinal section, is inclined at a ramp surface angle (22) relative to a rotational axis (39) of the rotor (23) which is less than 45°, in particular less than 30° or less than 25° or less than 20°.

3. Centrifuge according to claim 1 or 2, characterized in that the drive element (1) is a drive head (2) which can be connected in a rotationally fixed manner to a drive shaft.

4. Centrifuge according to one of the preceding claims, characterized in that the eccentric mass body (18) is guided into a groove or an elongated hole via an engagement of a guide projection (24, 25).

5. Centrifuge according to one of the preceding claims, characterized in that three eccentric mass bodies (18a, 18b, 18c) distributed over the circumference are guided on the drive element (1).

6. Centrifuge according to one of the preceding claims, characterized in thatthe drive element (1) has a form-locking element (15) which interacts with a counter-form-locking element (35) of the rotor (23) for the form-locking transmission of the drive torque.

7. Centrifuge according to one of the preceding claims, characterized in that the eccentric mass body (18) is secured in an initial position by a magnet (28, 36).

8. Centrifuge according to one of the preceding claims, characterized in that a) the drive element (1) has a drive element conical surface (5) and b) the rotor (23) has a rotor conical surface (31), wherein the drive element conical surface (5) and the rotor conical surface (31) are inclined opposite to the eccentric mass body ramp surface (21) and the rotor ramp surface (33), wherein preferably the drive element conical surface (5) and the rotor conical surface (31) are arranged on the side facing away from the drive from the eccentric mass body ramp surface (21) and the rotor ramp surface (33).

9. Centrifuge according to claim 8 in direct or indirect reference to claim 6, characterized in that the form-locking element (15) and the counter-form-locking element (35) are arranged between a) the drive element conical surface (5) and the rotor conical surface (31) and b) the eccentric mass body ramp surface (21) and the rotor ramp surface (33).

10. Centrifuge according to one of the preceding claims, characterized in that the rotor (23) has an insert sleeve (38) which forms the rotor ramp surface (33) and / or the counter-form-locking element (35) and / or the rotor conical surface (31).

11. Centrifuge according to one of the preceding claims, characterized in thatthe drive element (1) a) has a base body (4) which preferably forms the drive element conical surface (5), and b) has a cover body (3) connected to the base body (4), wherein an eccentric mass body receiving space (14) is formed between the base body (4) and the cover body (3), in which the eccentric mass body (18) is arranged and guided.

12. Centrifuge according to one of the preceding claims, characterized in that the eccentric mass body (18) is designed as a circular ring segment (19).

13. Centrifuge according to one of the preceding claims, characterized in that the or an eccentric mass body (18) has a locking element (45) which interacts with a groove or undercut (44) of the rotor (23).

14. Rotor (23) for a centrifuge according to one of claims 1 to 13, wherein preferably the rotor (23) has a rotor ramp surface (33) which is inclined in a semi-longitudinal section with a ramp surface angle (22) relative to a rotational axis (39) of the rotor (23) which is less than 45°, in particular less than 30° or less than 25° or less than 20°.

15. Drive head (2) for a centrifuge according to one of the preceding claims with a centrifugal force-operated coupling device (37), wherein the coupling device (37) has an eccentric mass body (18) movably guided on the drive head (2), characterized in that the eccentric mass body (18) is guided along a guide track (41) on the drive head (1), preferably with a translational degree of freedom.

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