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

TECHNICAL AREA OF INVENTION

[0001] The invention relates to a centrifuge, in particular a laboratory centrifuge. Centrifuges of the type presented here are used, for example, in biotechnology, the pharmaceutical industry, medical technology, and environmental analysis. Using such a centrifuge, a product, in particular a container or vessel with a sample or substance arranged therein, or a plurality of such products, is centrifuged at rotational speeds exceeding 3,000 rpm, e.g., exceeding 15,000 rpm. As a result of the centrifugation, accelerations acting on the product are generated, which can exceed, for example, 15,000 xg (in particular, more than 16,000 xg, more than 20,000 xg, up to more than 60,000 xg). The centrifugation is intended to separate 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 mixture, pressure and / or temperature can be precisely controlled during centrifugation. To name just a few examples, a laboratory centrifuge can be used in conjunction with polymerase chain reactions (PCR), hematocrit determination, cytological examinations, or the centrifugation of microtiters, blood bags, petroleum containers, or blood vessels, among other things. In the centrifuge, at least one product is arranged in a rotor or held against a rotor. The rotor can be, for example, a 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] To rotate the rotor containing the products as required for centrifugation, a rotor output element is coupled via a coupling device to a drive element of the laboratory centrifuge, which is typically 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. Alternatively, the drive torque may be transmitted via friction between coupling surfaces, whereby the contact force of the coupling surfaces may depend on the rotor's own weight and a force component of the coupling force.High demands must be placed on the operational reliability of the coupling device, especially due to aerodynamic effects resulting from high rotational speeds, large centrifugal forces, gyroscopic effects in the event of a visible impact on the laboratory centrifuge, and similar factors.

[0004] In the intended operation of a laboratory centrifuge, repeated assembly and disassembly of the rotor is necessary to successively analyze a large number of vessels containing substances to be centrifuged, either with the same rotor or with different rotors. It has been found that, given the manual effort and associated time required, as well as the operational safety implications, the use of manually operated coupling devices can be disadvantageous. For this reason, centrifugally actuated coupling devices are used, in which the rotor's output element is simply placed onto the drive element of the laboratory centrifuge, which is driven by the motor.Initially, the coupling between the drive and driven elements is achieved solely through friction due to the rotor's own weight. However, as the rotor's rotational speed increases, the coupling force of the centrifugally actuated clutch increases due to centrifugal force. The higher the rotational speed, the greater the coupling force generated by centrifugal force. It is also possible that a manually operated clutch is used in addition to such a centrifugally actuated clutch.

[0005] Known embodiments include an eccentric mass element, subjected to centrifugal force and generating the coupling force, mounted on the rotor. This eccentric mass element then engages a locking mechanism with a locking groove on a drive shaft. A problem here is that the centrifugal force acts radially outwards, while a locking action radially inwards with the locking groove of the drive shaft is required. For this reason, locking levers are used that can pivot about a pivot axis oriented tangentially to the circumferential direction. The center of gravity of the locking lever is located radially outside the pivot axis, so that pivoting due to the centrifugal force causes the radially inner lever portion of the locking lever to be subjected to radial inwards.Coupling devices in which a pivotable locking lever is held on the rotor are known, for example, from documents US2013 / 0237399 A1, US2013 / 0203581 A1, WO 2012 / 059151 A1, US 2014 / 0329658 A1 and WO 2011 / 001729 A1.

[0006] According to EP 3 012 027 B1, eccentric mass elements are also held on the rotor. In this case, however, they are designed as rolling or sliding elements. A centrifugal force acting on the eccentric mass elements is deflected via a guide track with further transmission elements, so that a radially inwardly oriented coupling force can be generated for locking with a drive shaft.

[0007] EP 2 321 058 B1 proposes an alternative design for a coupling device in which locking levers are pivotably mounted on a drive head about a pivot axis oriented parallel to a rotational axis of the drive shaft. When the locking levers are subjected to a radially outward-oriented coupling force due to centrifugal force, they pivot outwards. The locking levers contact corresponding ramp surfaces of a rotor sleeve via ramp surfaces. These ramp surfaces are inclined at an angle of 75° to 90° relative to the rotational axis of the drive shaft. The locking levers generate an axial force on these ramp surfaces, which clamps the rotor sleeve between the ramp surfaces of the locking levers and a truncated cone surface of the drive head that has an oppositely oriented opening angle. In this way, the rotor is axially fixed to the drive head.The drive head is bolted to one end face of the drive shaft. The pivot bolts, on which the locking levers are pivotally mounted on the drive head, protrude from the drive head and engage in corresponding bores in the rotor, thus enabling a positive-locking transmission of the drive torque between the drive head and the rotor.

[0008] From US patent 6,063,018 A, a laboratory centrifuge is known 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 by its own weight. When the drive element begins to move, the frictional force between the friction surfaces transmits the rotary motion to the rotor. In a transverse plane of the drive element, two clutch levers are mounted on the circumference, opposite each other, so that they can pivot outwards due to the 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 by the centrifugal force.In this way, a positive-locking axial connection of the rotor to the drive element is achieved. Due to the inclination of the coupling surfaces, the centrifugal force results in a speed-dependent axial force component, which increasingly increases the contact force of the frustoconical friction surfaces against each other with increasing speed. After the rotor is placed on the drive element, springs push the coupling levers radially outwards, thus locking the rotor even without rotation. To unlock the rotor, a button must be manually operated, which causes the coupling levers to move radially inwards, thereby unlocking the coupling mechanism.

[0009] From GB 2 502 894 A a centrifuge drive head is known which has two different coupling levers that can be pivoted outwards by a centrifugal force about a fixed pivot axis and which hold a rotor on the centrifuge drive head of a centrifuge in the axial direction.

[0010] Further state of the art is known in particular from DE 102012 011 531 A1, JP 2008-126130 A, DE 102021 121 259 A1, JP S56164040 U and US 2015 / 231648 A1. TASK OF INVENTION

[0011] The invention is based on the objective of proposing a centrifuge with an alternative centrifugally force-actuated coupling device for a rotationally fixed and axially secured coupling of a rotor with a drive element of a drive unit, which is particularly advantageous with regard to the safety of the coupling device during centrifuge operation and / or simple yet reliable operation and / or the complexity of the required components and / or the cost and / or the robustness and / or operability without manual actuators The invention is furthermore based on the objective of proposing a correspondingly improved rotor for a centrifuge and a correspondingly improved drive head for a centrifuge. SOLUTION

[0012] The object of the invention is achieved according to the invention by the features of the independent claims. Further preferred embodiments of the invention can be found in the dependent claims. DESCRIPTION OF THE INVENTION

[0013] 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 centrifugally force-actuated coupling device. In the coupling device according to the invention, the eccentric mass is not movably guided on the rotor. Rather, the eccentric mass of the coupling device is movably guided on the drive element. The rotor preferably has a rotor retraction. As a result of the centrifugal force, the eccentric mass can be moved behind the rotor retraction, thereby bringing about the coupling effect. Alternatively or cumulatively, it is possible that the eccentric mass (in particular to bring about the coupling effect and / or an axial contact force) can be moved by the centrifugal force against a ramp surface, in particular a rotor retraction ramp surface or rotor ramp surface.

[0014] According to the invention, it is proposed that the eccentric mass body is not pivotably mounted about a pivot axis, but rather guided along a guide track on the drive element. The guide track can define a path along a curved degree of freedom, with at least one component of the guide track being oriented radially. The eccentric mass body can thus be moved along the guide track by means of centrifugal force. Preferably, the eccentric mass body has a translational degree of freedom relative to the drive element, which can be oriented radially or at a fixed acute angle to the radial direction.

[0015] The design according to the invention is based in particular on the realization that, according to the prior art, locking levers mounted on the drive element require a large installation space and are not optimal with regard to mass utilization, since locking lever parts arranged on both sides of a pivot axis generate opposing pivoting torques, so that only a difference in the pivoting torques can be used for the locking effect. In addition, the rotatable mounting of a locking lever requires a bearing by means of a sliding or rolling bearing, which may place high demands on manufacturing, requires additional components such as rolling elements or sliding sleeves and tighter manufacturing tolerances in the area of ​​the bearing surfaces, and is susceptible to wear.In contrast, in the extreme case of the invention, a block-like eccentric mass element can be used, which is guided exclusively by planar sliding contacts with a guide track. Such an eccentric mass element can be manufactured simply and cost-effectively and is subject to low wear even under continuous operation at high speeds. The contact surface of the eccentric mass element with the guide track allows the surface pressures to be kept low, thus predetermining and reducing the mechanical stresses. Furthermore, in comparison to the aforementioned locking lever, the entire mass of the eccentric mass element can be used to generate the centrifugal force and thus the coupling force.

[0016] It is possible that, after moving behind the rotor retraction, the eccentric mass body provides a positive locking or securing action due to centrifugal force. In one embodiment of the invention, the eccentric mass body has an eccentric mass body ramp surface, while the rotor or a rotor retraction has a rotor ramp surface (hereinafter also referred to as the common "ramp surface"). In a semi-longitudinal section, the ramp surfaces are inclined relative to the rotor's axis of rotation at a ramp surface angle of less than 45° (in particular, less than 30°, 25°, or 20°).This embodiment of the invention is based on the understanding that, for centrifuges known from the prior art, releasing the locking lever after the centrifuge has finished requires separate measures, such as pressing a release button, or the locking lever must be actuated by a spring that, when the centrifugal force ceases, returns the locking lever to its initial position, allowing the rotor to be removed from the drive element. However, if the small ramp surface angle proposed by the invention is selected, a return movement of the eccentric mass body can be achieved simply 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 independently 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.

[0017] Within the scope of the invention, the drive element can be designed in any way desired. For example, it is entirely possible for the drive element to be formed directly from the drive shaft of the drive motor. In a particular embodiment of the invention, the drive element is a (one- or multi-part) drive head that is rotationally fixed to the drive shaft of the drive motor. It is possible, for instance, for the drive head to be connected to the drive shaft via a shaft-hub connection, known per se, which transmits a drive torque, and for securing it to the drive shaft by means of a fastening screw bolted to the end face of the drive shaft.

[0018] The invention offers various possibilities for holding and guiding the eccentric mass body on the drive element, as long as the guidance follows a straight or curved guide path. A particularly simple method of guiding the eccentric mass body involves the engagement of a guide projection (in particular a bolt or pin) in a groove or slot. For example, the eccentric mass body can have the groove or slot, while the drive element then has the guide projection, bolt, or pin (although a reversed arrangement of the slot or groove on the one hand and the guide projection on the other is also possible).

[0019] Within the scope of the invention, any number of eccentric mass elements can be used, wherein the eccentric mass elements can have the same or different geometries and can be arranged at the same or different radii. Preferably, several eccentric mass elements are arranged and guided uniformly around the circumference of the drive element. A particularly compact yet efficient design of the centrifuge is achieved when exactly three eccentric mass elements are guided around the circumference, evenly distributed. The three eccentric mass elements ensure stable support between the rotor and the drive element in the required directions. Furthermore, the three circumferentially distributed eccentric mass elements can have a relatively large mass, thus providing a high degree of stability.

[0020] Within the scope of the invention, it is entirely possible for the transmission of drive torque between the drive element and the rotor to occur via a frictional connection, with the frictional connection preferably being established in the area of ​​adjacent transverse surfaces, ramp surfaces, or conical surfaces. The contact force generating the friction can be caused by the weight of the rotor and / or at least a component of the centrifugal force or coupling force. However, in one embodiment of the invention, the drive element additionally features a positive locking element. This positive locking element of the drive element then interacts with a corresponding positive locking element of the rotor to transmit the drive torque positively.There are numerous possibilities for the design of the positive locking element and the counter-positive locking element, and possibilities known from the prior art can also be used within the scope of the invention. Preferably, the positive locking element and the counter-positive locking element have a non-circular cross-section that transmits the drive torque. For example, the positive locking element and the counter-positive locking element can be designed as a type of toothing with any tooth geometry or as a circular cross-section with a superimposed shaft contour. Preferably, the positive locking element and the counter-positive locking element form insertion aids or chamfers that allow the rotor to be mounted onto the drive element not only when the rotor is approached from the drive element in the exact angular position about the axis of rotation.

[0021] It may be desirable to secure the eccentric mass in its initial position, which corresponds to the released coupling device. Such securing in the initial position can be advantageous to prevent the eccentric mass from undesirably leaving its initial position for a removed rotor, which could then make attaching a new rotor impossible or difficult. Any detent device or a spring (see the prior art mentioned above) can be used to secure the eccentric mass in its initial position, to name just a few examples that do not limit the invention. In one proposal of the invention, the eccentric mass is secured in an initial position by a magnet. For example,The drive element and the eccentric mass body feature (permanent) magnets whose attracting poles are aligned and closely spaced in the initial position, while their distance increases as the drive element leaves the initial position. In addition to its locking effect in the initial position, a magnet can also help the eccentric mass body return to its initial position after centrifugation has ceased. The magnet and the locking effect it provides are designed so that the lock is automatically released if the drive element and eccentric mass body rotate at a speed threshold up to which the locking effect is desired. In this case, the rotational speed generates a centrifugal force acting on the eccentric mass body that can overcome the magnetic locking force.

[0022] In a further embodiment 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, with the result that the rotor, with its rotor conical surface and rotor ramp surface, is "trapped" between the drive element conical surface and the eccentric mass body ramp surface. The opposing angles between the drive element conical surface and the rotor conical surface, on the one hand, and between the eccentric mass body ramp surface and the rotor ramp surface, on the other hand, can be the same or different.

[0023] Alternatively, the drive element cone surface and the eccentric mass body ramp surface are "trapped" between the rotor cone surface and the rotor ramp surface. In this configuration, the centrifugal force and the resulting coupling force generate a contact force on the aforementioned cone and ramp surfaces, resulting in axial clamping of the rotor to the drive element.

[0024] While other arrangements are certainly possible, the invention proposes a further configuration in which the drive element cone surface and the rotor cone surface are arranged on the side facing away from the drive (i.e., above the eccentric mass body ramp surface and the rotor ramp surface for a vertical arrangement of the rotor axis with the drive located below). This enables a particularly compact, reliable, and durable design of the resulting shaft-hub connection for holding the rotor and for the coupling device.

[0025] The invention also offers numerous possibilities for arranging the positive locking element and the counter-positive locking element in the axial direction and relative to the cone surfaces and ramp surfaces. In one embodiment, the positive locking element and the counter-positive locking element are arranged between, on the one hand, the drive element cone surface and the rotor cone surface, and on the other hand, between the eccentric mass body ramp surface and the rotor ramp surface. This configuration preferably displaces the positive locking element and the counter-positive locking element away from the end region of the drive element located inside the rotor. This can result in a particularly rigid and reliable transmission of the drive torque between the positive locking element and the counter-positive locking element, and may also provide more material in the area of ​​the drive element for shaping and supporting the positive locking element.

[0026] The rotor can form the described functional surfaces for interaction with the drive element in any desired manner, and can have any number of components for this purpose. According to one aspect of the invention, the rotor has a (one- or multi-part) insert sleeve. The drive element can then enter this insert sleeve and bring about at least some of the necessary interactions and provide the functional surfaces. For this purpose, the insert sleeve can form the rotor ramp surface and / or the mating positive locking element. Optionally, the insert sleeve can also form the rotor cone surface.

[0027] There are also numerous possibilities for the design of the drive element, particularly the drive head, with the drive element preferably being designed in multiple parts. According to one embodiment of the invention, the drive element comprises a base body. Preferably, this base body forms the conical surface of the drive element. Furthermore, the drive element has a cover body that is connected to the base body. An eccentric mass receiving chamber is formed between the base body and the cover body. The eccentric mass can then be movably arranged within this receiving chamber. Within this receiving chamber, the eccentric mass is also guided along the guide track. This guidance is preferably achieved by a contact surface between the eccentric mass and the base body and / or the cover body.Such a contact surface can have a surface normal oriented parallel to the rotor's axis of rotation. Furthermore, it is possible that the base body and / or the cover body have radially oriented ribs by which (possibly in addition to the guide projection, groove, or slot) the eccentric mass body can be guided, in which 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.

[0028] There are numerous possibilities for the shape of the (one-piece or multi-piece) eccentric mass body. In one embodiment of the invention, the eccentric mass body is designed (at least to a rough approximation) as a (one-piece or multi-piece) circular ring segment. A radially outer end face of the circular ring segment can then form the ramp surface of the eccentric mass body. For example, the centers of the inner and outer surfaces of the circular ring segment can be arranged radially offset from each other. Thus, for instance, the centers can be offset from each other by the displacement path of the eccentric mass body, resulting in a particularly compact design.

[0029] 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 ensures a very compact design despite the high mass of the eccentric mass bodies.

[0030] In addition to the described connection and securing measures for attaching the rotor to the drive head, any other connection and / or securing measures can be used. According to one aspect of the invention, the eccentric mass body has a locking element that interacts with a groove or undercut in the rotor. This interaction, in particular the engagement of the locking element in the groove or behind the undercut, ensures a positive locking connection. Unlocking can occur, for example, when the rotor is at rest due to the magnetic force of the magnets, by means of a manually operated unlocking mechanism, or via a spring.

[0031] Another solution to the problem underlying the invention is a rotor designed for a centrifuge, as previously described, and configured accordingly. In this case, the rotor has a ramp surface inclined in a semi-longitudinal section at a ramp surface angle relative to the rotor's axis of rotation that is less than 45° (in particular, less than 30°, less than 25°, or less than 20°). To name just a few examples, the rotor can have a rotor recess behind which the eccentric mass body can be moved by centrifugal force. The rotor can have a counter-positive locking element that interacts with the positive locking element of the drive element for the positive-locking transmission of the drive torque. The rotor can have a rotor cone surface, which can be inclined opposite to the rotor ramp surface. It is possible that the rotor ramp surface can be located further outwards, i.e., in the direction of the drive, than the rotor cone surface. The rotor's counter-positive locking element can be located between the rotor cone surface and the rotor ramp surface. The rotor can have an insert sleeve that forms the rotor ramp surface and / or the counter-positive locking element and / or the rotor cone surface.

[0032] Another solution to the problem underlying the invention is a drive head designed and configured for a centrifuge as previously described. The drive head has a centrifugally actuated clutch device comprising an eccentric mass element movably guided on the drive head. The eccentric mass element is guided along a guide track on the drive head, preferably with one translational degree of freedom.

[0033] Advantageous further developments of the invention result from the patent claims, the description and the drawings.

[0034] The advantages of features and combinations of features mentioned in the description are merely exemplary and can have an effect alternatively or cumulatively, without the advantages necessarily having to be achieved by embodiments according to the invention.

[0035] Regarding the disclosure content—not the scope of protection—of the original application documents and the patent, the following applies: Further features can be derived from the drawings—in particular, the geometries depicted and the relative dimensions of several components to one another, as well as their relative arrangement and functional connection. The combination of features from different embodiments of the invention or from features of different claims is also possible, deviating from the chosen cross-references of the 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 from different 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.

[0036] The features mentioned in the claims and the description are to be understood, with regard to their number, as meaning that exactly that 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 body or magnet, this is to be understood as meaning that exactly one eccentric mass body or magnet, two eccentric mass bodies or magnets, or more eccentric mass bodies or magnets are present. The features listed in the claims may be supplemented by further features or may be the only features that the subject matter of the respective claim possesses.

[0037] The reference numerals contained in the patent claims do not constitute a limitation of the scope of the subject matter protected by the patent claims. They serve only the purpose of making the patent claims easier to understand. BRIEF DESCRIPTION OF THE FIGURES

[0038] The invention will now be further explained and described with reference to preferred embodiments shown in the figures. Fig. 1 shows a drive element designed as a drive head of a laboratory centrifuge in a spatial exploded view. Fig. 2 shows a rotor with a drive head arranged therein according to Fig. 1 in a spatial semi-longitudinal section, with the coupling device detached. 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 , with the coupling device in the released starting position. Fig. 5shows the drive head according to Fig. 1 and 4 in the released starting position in a spatial view. Figs. 6 to 9 show the Figs. 2 to 5 corresponding representations, although here the coupling device is in the coupled position. Fig. 10 shows another 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 starting position and assumed a coupled position. Fig. 14 shows another embodiment of a drive head in the coupling area with a rotor in a detail of a semi-longitudinal section. FIGURE DESCRIPTION

[0039] In the following figure descriptions, some components or features are identified with the same reference numbers, which can then be distinguished from one another by the supplementary letter a, b,... In this case, the component or feature can also be referred to without the additional letter, in which case one component or feature, several components or features, or all components or features can be addressed.

[0040] Fig. 1 Figure 1 shows a drive element 1, which is designed as a drive head 2. The drive head 2 can be fixed to a drive shaft of a drive motor of the centrifuge (not shown here) in a rotationally fixed manner. The drive head 2 has a cover body 3 and a base body 4.

[0041] The base body 4 forms a drive element conical surface 5 in its lower end region, which widens from a cylindrical guide surface 6. While not strictly necessary, the base body 4 also integrally forms a star body 7. The star body 7 has radially oriented ribs 8 extending from a star sleeve 9.

[0042] The cover body 3 has a circular disc 10, which is placed on top of the star body 7 and secured to the star body 7 by screws 11a, 11b, 11c. These screws 11a, 11b, 11c are threaded through bores 12a, 12b, 12c in the circular disc 10, which have 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 receiving spaces 14a, 14b, 14c are formed. These spaces are open radially outwards, bounded radially inwards by the star sleeve 9, and bounded circumferentially by the ribs 8a, 8b, 8c.

[0043] The cover body 3 has a positive locking element 15 on its outer side.

[0044] According to Fig. 1 The positive locking element 15 has a cylindrical surface 16 with a star-shaped cross-section or an arbitrarily shaped toothing, a polygon, or the like.

[0045] The drive head 2 has a recess 17 extending in the direction of a rotation axis 39. Fig. 2 It can be seen that this recess 17 has a frustoconical conical surface in its lower end region, which extends 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.

[0046] In each of the eccentric mass receiving spaces 14a, 14b, 14c, an eccentric mass body 18a, 18b, 18c is arranged. The eccentric mass bodies 18 are each designed as circular ring segments 19a, 19b, 19c. Preferably, the radially inner end face of the circular ring segments 19 is cylindrical segment-shaped. The end faces of the circular ring segments 19 in the circumferential direction are oriented radially to the axis of rotation 39. The lower and upper surfaces of the circular ring segments 19 are oriented parallel to each other with a surface normal that is oriented parallel to the axis of rotation 39. The outer lateral surface 20 of the circular ring segments 19 is frustoconical segment-shaped and forms an eccentric mass ramp surface 21, which is inclined relative to an axis of rotation 39 at a ramp surface angle 22 that is preferably 15° ± 5°.

[0047] Each of the eccentric mass body receiving spaces 14 has two guide projections 24, 25, which, in the illustrated embodiment, are designed as guide pins 26, 27 oriented parallel to the axis of rotation 39. The guide pins 26, 27 engage in radially oriented grooves or slots on the underside of the eccentric mass bodies 18, the longitudinal axis of which is preferably oriented radially to the axis of rotation 39. The engagement of the guide pins 26, 27 in the grooves or slots ensures that the eccentric mass body 18 is guided such that its movement occurs in a radial direction to the axis of rotation 39.

[0048] 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.

[0049] When the cover body 3 is mounted to the base body 4, the eccentric mass elements 18 are trapped in the eccentric mass element receiving spaces 14 between the cover body 3 and the contact surface on the base body 4 in the direction of the axis of rotation 39, thus preventing the guide pins 26, 27 from exiting the grooves or slots. The maximum radial outward movement of the eccentric mass elements 18 is determined by the length of the grooves or slots.

[0050] Fig. 2 Figure 1 shows a partial 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 axis of rotation 39. The recess 30 has the following sections in the direction of the axis of rotation 39, which are directly adjacent to one another: a frustoconical rotor cone surface 31, a cylindrical guide surface 32, a rotor step-back ramp surface 33 inclined with the ramp surface angle 22 relative to the axis of rotation 39, which is preferably formed in the area of ​​a rotor step-back 40 of the rotor 23, which can, for example, form an undercut, a cylindrical intermediate section 34 in the area 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.

[0051] The counter-form-locking element 35 has an inner surface whose cross-section corresponds to the cross-section of the lateral surface 16 of the form-locking element 15, so that the form-locking element 15 can be arranged precisely and positively in the counter-form-locking element 35 for the transmission of a drive torque.

[0052] 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.

[0053] 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 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 and 36.

[0054] When the drive motor is actuated, the drive motion is transmitted to the drive head 2 via the shaft-hub connection between the drive shaft and the drive head 2. This motion is then transmitted to the rotor 23 via the positive locking mechanism between the positive locking element 15 and the counter-positive locking element 35. If the centrifugal force acting on the eccentric mass elements 18 overcomes the magnetic locking force, the eccentric mass elements 18 slide radially outwards in the eccentric mass element receiving spaces 14 until the eccentric mass elements 18, with their ramp surfaces 21, come into contact with the rotor ramp surfaces 33. The centrifugal forces acting in the resulting contact surface are converted into an axial force due to the ramp surface angle 22. This axial force presses the base body 29 of the rotor 23, with its rotor cone surface 31, against the drive element cone surface 5.

[0055] 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.

[0056] Fig. 3 , 4 and 5 show the drive head 2 in a state of the coupling device 37 in which the eccentric mass elements 18 are in their initial position. In contrast, show Figs. 6 to 9An operating state of the coupling device 37 in which the eccentric mass elements 18 are in the coupled or locking position. If, after centrifugation has ended, removal of the rotor 23 from the drive head 2 is desired, the eccentric mass elements 18 may still be in the locking position. However, if removal forces oriented parallel to the axis of rotation 39 are then applied to the rotor 23, these removal forces, due to the ramp surface angle 22 at the eccentric mass element ramp surfaces 21, generate a force component that is oriented radially inwards, allowing the eccentric mass elements 18 to slide radially inwards until they release the rotor 23 and the initial position of the eccentric mass elements 18 can be secured by the interaction between the magnets 28, 36.

[0057] In the Figs. 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 no guidance is provided by contact surfaces in these areas, but rather that there is clearance. In this case, guidance can be achieved 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.

[0058] For the in Figs. 1 to 9 In the illustrated embodiment, for a rotor 23 mounted on the drive head 2, the positive locking element 15 and the counter-positive locking element 35, the eccentric mass body ramp surface 21 and the rotor ramp surface 33, and the drive element cone surface 5 and the rotor cone surface 31 are arranged in this axial order, with the positive locking element 15 being located furthest in the rotor 23. Figs. 10 to 13Another embodiment is shown in which the drive element cone surface 5 and the rotor cone surface 31, the positive locking element 15 and the counter-positive 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 cone surface 5 and the rotor cone surface 21 are arranged furthest inside the rotor 23. This embodiment allows, for example, the positive locking element 15 and the counter-positive locking element 35 to have a larger diameter, thus ensuring improved transmission of the drive torque.Furthermore, this design may also allow the arrangement of the positive locking element 15 and the counter-positive locking element 35 and / or the eccentric mass body ramp surface 21 and the rotor ramp surface 33 in a material area of ​​the rotor 23 that has a smaller axial distance from the drive, thus providing rigid support and reducing the lever arm of any forces. Alternatively or cumulatively, this design may allow more material to be made available in the area of ​​the aforementioned elements, potentially resulting in improved strength.

[0059] For the in Figs. 1 to 9 In the illustrated embodiment, the functional surfaces with which the rotor 23 interacts with the drive head 2 are formed integrally with the base body 29. In contrast, according to the embodiment in Figs. 10 to 13These functional surfaces are at least partially formed by an insert sleeve 38, which can be inserted into and screwed to the base body 29. In the illustrated embodiment, the insert sleeve 38 forms both the rotor ramp surface 33 and the counter-locking element 35, while the rotor cone surface 31 is formed by the base body 29.

[0060] Preferably, the eccentric mass body ramp surfaces 21 are rounded in the area of ​​the axial edges.

[0061] The coupling device 37 can be released, in particular without tools, by applying release forces to the rotor 23. It is possible that, after operation of the centrifuge and once the rotor 23 has come to a standstill, the magnets 28, 36 automatically move the eccentric mass elements 18 back to their unlocked initial position. Alternatively, or cumulatively, the release forces manually applied to the rotor 23 by the user are converted, via the inclination angle of the eccentric mass element ramp surfaces 21, into a force that moves the eccentric mass elements 18 back to their unlocked initial position.

[0062] 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 aluminium or stainless steel.

[0063] 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 that the guide track 41 is formed by the guiding projections 24, 25 in the grooves or slots of the eccentric mass bodies 18. Preferably, this ensures radial guidance of the eccentric mass bodies 18 and provides a radially external or radially internal stop for the movement of the eccentric mass bodies 18. It is also possible that the guide track 41 is formed by guiding the eccentric mass bodies 18 between the underside of the cover body 3 and the top side of the base body 4. This guidance ensures, in particular, that the eccentric mass bodies 18 cannot tilt and / or that they cannot move axially.It is also possible that the guide track 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).

[0064] In contrast to 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.

[0065] Fig. 14Figure 1 shows an embodiment in which the connection between the drive head 2 and the rotor 23 is not solely achieved and secured by clamping the rotor 23 with its rotor cone surface 31 and rotor ramp surface 33 between the eccentric mass body ramp surface 21 and the output element cone surface 5. Instead, an additional connection and securing is achieved 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. In the illustrated embodiment, the locking element 45 abuts directly onto the eccentric mass body ramp surface 21, with the locking element 45 being located in the end region of the eccentric mass body ramp surface 21 that has the shorter distance from the axis of rotation 39.When the eccentric mass bodies 18 are moved radially outwards 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 the removal of the rotor 23 from the drive head 2 in a removal direction corresponding to the direction of the axis of rotation 39.

[0066] 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 segment surfaces whose surface normal corresponds to the axis of rotation 39, or the contact surfaces 46, 47 can form any conical angle to the axis of rotation 39. Fig. 14Figure 1 shows an embodiment in which the contact surface 47 of the groove or undercut 44 has a nose 48 that engages in a recess 49 of the contact surface 46.

[0067] Unlocking can occur when, as the rotor 23 decelerates, the force exerted by the magnets 28, 36 on the eccentric mass bodies 18 becomes greater than the radially outward frictional force component acting in the contact surfaces and the remaining centrifugal force acting on the eccentric mass bodies 18. Alternatively or cumulatively, unlocking can be achieved, for example, via a spring or a manually operated unlocking device.

[0068] In 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 that first eccentric mass bodies form the eccentric mass body ramp surfaces 21, while the locking elements 45 are formed by the second eccentric mass body. REFERENCE MARK LIST

[0069] 1 Drive element 2 Drive head 3 Cover body 4 Base body 5 Drive element cone surface 6 Guide surface 7 Star body 8 Rib 9 Star sleeve 10 Circular disc 11 Screws 12 Bore 13 Threaded bores 14 Eccentric mass body receiving chamber 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 bolt 27 Guide bolt 28 Magnet 29 Base body 30 Recess 31 Rotor cone surface 32 Guide surface 33 Rotor ramp surface 34 Intermediate section 35 Counter-positive locking element 36 Magnet 37 Coupling device 38 Insert sleeve 39 Rotary axis 40 Rotor recess 41 Guide track 42 Guide surface 43 Guide surface 44 Groove, undercut 45 Locking element 46 Contact surface 47 Contact surface 48 Nose 49 Recess

Claims

1. Centrifuge comprising a rotor (23), which is connected to a drive element (1) via a centrifugal-force-actuated clutch device (37), wherein the clutch device (37) comprises an eccentric mass body (18) movably guided on the drive element (1), wherein the eccentric mass body (18) can preferably be moved by centrifugal force behind a rotor recess (40) and / or against a rotor ramp surface (33), characterized in that the eccentric mass body (18) is not mounted pivotably about a pivot axis, but is guided along a guide path (41) on the drive element (1), preferably with a translational degree of freedom.

2. Centrifuge according to claim 1, characterized in that the eccentric mass body (18) comprises an eccentric mass body ramp surface (21) and the rotor (23) comprises a rotor ramp surface (33), which, in a longitudinal half-section, are inclined at a ramp surface angle (22) relative to an axis of rotation (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) that 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 by an engagement of a guide projection (24, 25) into a groove or an elongated hole.

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

6. Centrifuge according to one of the preceding claims, characterized in that the drive element (1) comprises a positive-locking element (15), which interacts with a complementary positive-locking element (35) of the rotor (23) for the positive-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 means of a magnet (28, 36).

8. Centrifuge according to one of the preceding claims, characterized in that a) the drive element (1) comprises a drive element conical surface (5), and b) the rotor (23) comprises a rotor conical surface (31), wherein the drive element conical surface (5) and the rotor conical surface (31) are inclined in the opposite direction 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 opposite the drive relative to the eccentric mass body ramp surface (21) and the rotor ramp surface (33).

9. Centrifuge according to claim 8, directly or indirectly referring back to claim 6, characterized in that the positive-locking element (15) and the complementary positive-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) comprises an insert sleeve (38), which forms the rotor ramp surface (33) and / or the complementary positive-locking element (35) and / or the rotor conical surface (31).

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

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 a or the eccentric mass body (18) comprises 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 the rotor (23) comprises a rotor ramp surface (33), which, in a longitudinal half-section, is inclined at a ramp surface angle (22) relative to an axis of rotation (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 claims 3 to 13, comprising a centrifugal-force-actuated clutch device (37), wherein the clutch device (37) comprises 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 path (41) on the drive head (2), preferably with a translational degree of freedom.

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