EP4487961A1 - Centrifuge, rotor for a centrifuge and drive head for a centrifuge - Google Patents

Abstract

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

Description

The invention relates to a centrifuge, in particular a laboratory centrifuge. Centrifuges of the type in question are used, for example, in biotechnology, the pharmaceutical industry, medical technology and environmental analysis. A centrifuge of this type is used to centrifuge a product, in particular a container or vessel with a sample or substance arranged therein, or a large number of such products, at speeds that can be more than 3,000 rpm, for example more than 15,000 rpm. As a result of the centrifugation, accelerations acting on the product are to be generated, which can be, for example, more than 15,000 x g (in particular more than 16,000 x g, more than 20,000 x g up to more than 60,000 x g). The 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 mixture of substances, the pressure and/or temperature conditions can also be controlled during centrifugation. To name just a few examples, a laboratory centrifuge can be used in connection with a polymerase chain reaction (PCR), a determination of the hematocrit, cytological examinations or the centrifugation of microtiters, blood bags, petroleum containers or 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 swing-out rotor.

Furthermore, the invention relates to a rotor for a centrifuge and a drive head for a centrifuge.

STATE OF THE ART

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 on the drive element and thus the rotor on the driven drive shaft of the motor. It is possible that the coupling device also serves to positively transfer the drive torque from the drive shaft to the rotor. It is also possible that the drive torque is transferred via a frictional connection of coupling surfaces, whereby the contact force of the coupling surfaces can be dependent on the rotor's own weight 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 that arise at high speeds, the large centrifugal forces, gyroscopic effects in the event of a visible impact on the laboratory centrifuge and the like.

When the laboratory centrifuge is used as intended in a laboratory, the rotor must be repeatedly assembled and disassembled in order to be able to successively examine a large number of vessels with substances to be centrifuged using the same rotor or different rotors. It has been found that the use of manually operated coupling devices can be disadvantageous in view of the manual operation effort and the associated time required, but also in terms of operational safety. For this reason, centrifugal force-operated coupling devices are used in which the output element of the rotor is simply placed on the drive element of the laboratory centrifuge driven by the motor. While initially only a frictional connection between the drive element and output element due to the rotor's own weight ensures the coupling between the drive element and output element, the coupling force of the centrifugal force-operated coupling device increases as the speed of the rotor increases due to centrifugal force. The higher the speed, the greater the clutch force generated by the centrifugal force. It is also possible that a manually operated clutch device is used in addition to such a centrifugal force-operated clutch device.

There are known embodiments in which an eccentric mass body, which is subjected to the centrifugal force and causes the coupling force, is mounted on the rotor. The The eccentric mass body then locks with a locking groove of a drive shaft. The problem here is that the centrifugal force acts radially outwards, while a locking radially inwards with the locking groove of the drive shaft is required. 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 is located radially outside of the pivot axis, so that pivoting due to the centrifugal force results in the radially inner lever part of the locking lever being acted upon radially inwards. Coupling devices in which a pivotable locking lever is held on the rotor are known, for example, from the publications US 2013/0237399 A1 , US 2013/0203581 A1 , WO 2012/059151 A1 , US 2014/0329658 A1 and WO 2011/001729 A1 known.

Also according to EP 3 012 027 B1 Eccentric mass bodies are held on the rotor. In this case, however, these are designed as rolling or sliding bodies. A centrifugal force acting on the eccentric mass bodies is diverted via a guide track with additional transmission bodies, so that a radially inward-oriented coupling force can be generated for locking with a drive shaft.

EP 2 321 058 B1 proposes another design of a coupling device in which locking levers are mounted on a drive head so as to be pivotable about a pivot axis that is oriented parallel to a rotational axis of the drive shaft. If the locking levers are subjected to a radially outwardly oriented coupling force as a result of the centrifugal force, they pivot outwards. The locking levers come into contact with corresponding ramp surfaces of a sleeve of the rotor with ramp surfaces. The ramp surfaces are inclined at an angle of 75° to 90° to the rotational axis of the drive shaft. The locking levers generate an axial force on the ramp surfaces, with which the sleeve of the rotor is clamped between the ramp surfaces of the locking levers and a truncated cone surface of the drive head with an oppositely oriented opening angle. In this way, the rotor is axially fixed on the drive head. The drive head is screwed to one end face 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 are accommodated in corresponding holes in the rotor, whereby a positive transmission of the drive torque between the drive head and the rotor can take place.

Out of US 6,063,018 A A laboratory centrifuge is known in which a drive element with a truncated cone-shaped drive surface is driven by a motor. The rotor has a corresponding truncated cone-shaped inner friction surface, with which the rotor is pressed onto the truncated cone-shaped friction surface of the drive element due to its own weight. When the drive movement of the drive element begins, the friction force between the friction surfaces leads to the transmission of the rotary movement to the rotor. In a transverse plane of the drive element, two clutch levers are distributed around the circumference and opposite one another and are mounted so that they can pivot outwards due to the centrifugal force. Coupling surfaces of the clutch levers that are inclined relative to the transverse direction of the drive element are pressed onto corresponding coupling surfaces of the rotor due to the centrifugal force. In this way, on the one hand, a positive axial securing of the rotor on the drive element is brought about. Due to the inclination of the clutch surfaces, the centrifugal force leads to a speed-dependent axial force component, which increases the contact pressure of the frustoconical friction surfaces against each other as the speed increases. After the rotor is placed on the drive element, springs press the clutch levers radially outwards, which locks the rotor even without rotation. To unlock the rotor, a button must be manually operated, which causes the clutch levers to move radially inwards, thereby unlocking the clutch device.

Further state of the art is particularly evident from DE 102012011 531 A1 , JP 2008-126130 A , DE 10 2021 121 259 A1 and JP S56164040 U known.

TASK OF THE INVENTION

• der Sicherheit der Kupplungseinrichtung im Betrieb der Zentrifuge und/oder
• einer einfachen, aber dennoch zuverlässigen Bedienung und/oder
• der Komplexität erforderlichen Bauelemente und/oder
• der Kosten und/oder
• der Robustheit und/oder
• einer Bedienbarkeit ohne manuelle Betätigungselemente

verbessert ist. Des Weiteren liegt der Erfindung die Aufgabe zugrunde, einen entsprechend verbesserten Rotor für eine Zentrifuge sowie einen entsprechend verbesserten Antriebskopf für eine Zentrifuge vorzuschlagen.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
• a simple, yet reliable operation and/or
• the complexity required components and/or
• the costs and/or
• the robustness and/or
• operability without manual controls

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

The object of the invention is achieved according to the invention with the features of the independent patent claims. Further preferred embodiments according to the invention can be found in the dependent patent claims.

DESCRIPTION OF THE INVENTION

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-operated 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, whereby the coupling effect can be brought about. 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.

According to the invention, it is proposed that the eccentric mass body is not mounted so as to be pivotable about a pivot axis, but is guided along a guide track on the drive element. In this case, the guide track can provide guidance along a curved degree of freedom, with at least one component of the guide track being oriented in the radial direction. The eccentric mass body can thus be moved along the guide track by means of the centrifugal force. The eccentric mass body preferably has a translational degree of freedom relative to the drive element, which is oriented in the radial direction. or can be oriented at a fixed acute angle to the radial direction.

The design according to the invention is based in particular on the knowledge 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 the utilization of the mass, since locking lever parts arranged on both sides of a pivot axis generate opposing pivoting moments, so that only a difference in the pivoting moments 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 production, requires additional components such as rolling elements or sliding sleeves and lower manufacturing tolerances in the area of the bearing surfaces and is susceptible to wear. In contrast, within the scope of the invention, in extreme cases a block-like eccentric mass body can be used which is guided exclusively via flat sliding contacts with a guide track. Such an eccentric mass body can be manufactured simply and inexpensively and is subject to little wear even during continuous operation at high speeds. The contact surface of the eccentric mass body with a guide track allows the surface pressures to be kept low, thus specifying and reducing the mechanical stresses in the design. In comparison to the locking lever mentioned above, the entire mass of the eccentric mass body can also be used to generate the centrifugal force and thus the coupling force.

It is possible that the eccentric mass body ensures a positive locking or locking after the movement behind the rotor recess as a result of the centrifugal force. For 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 referred to as the common "ramp surface"). The ramp surfaces are inclined in a semi-longitudinal section with respect to the axis of rotation of the rotor at a ramp surface angle with respect to the axis of rotation of the rotor that is less than 45° (in particular less than 30° or less than 25° or less than 20°). This embodiment of the invention is based on the knowledge that for centrifuges known from the prior art, the release of the locking lever after the centrifuge has finished operating requires separate measures such as pressing a release button or locking levers must be actuated by a spring that returns the locking lever to the Starting position in which 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 caused 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 alone causes a return movement to the starting position, which corresponds to the released coupling device. The ramp surface angle is preferably selected such that no self-locking occurs in the area of contact of the ramp surfaces.

Within the scope of the invention, the drive element can be designed in any way. It is certainly possible for the drive element to be formed directly from the drive shaft of the drive motor. For a particular proposal of the invention, the drive element is a (single or multi-part) drive head that is held in a rotationally fixed manner on the drive shaft of the drive motor. It is possible, for example, for the drive head to be connected to the drive shaft via a shaft-hub connection known per se that transmits a drive torque, whereby securing can be achieved via a fastening screw screwed to the front of the drive shaft.

Within the scope of the invention, there are many different ways of holding and guiding the eccentric mass body on the drive element, as long as it is guided along a straight or curved guide path. A particularly simple way of guiding the eccentric mass body can be to ensure that the guide is ensured by means of an engagement of a guide projection (in particular a bolt or pin) in a groove or an elongated hole. For example, the eccentric mass body can have the groove or the elongated hole, while the drive element then has the guide projection, bolt or pin (although an inverted arrangement of the elongated hole or groove on the one hand and the guide projection on the other is also possible).

Within the scope of the invention, any number of eccentric mass bodies can be used, whereby the eccentric mass bodies can have the same or different geometries and can be arranged at the same or different radii. Preferably, several eccentric mass bodies are arranged and guided evenly in the circumferential direction on the drive element. A particularly compact but efficient design of the centrifuge is achieved when exactly three eccentric mass bodies are guided on the drive element, evenly distributed over the circumference. The three eccentric mass bodies ensure stable support between the rotor and the drive element in the required directions. On the other hand, the three eccentric mass bodies distributed in the circumferential direction can have a relatively large mass, which can bring about a high securing effect.

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, with the frictional connection preferably being brought about 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. For one proposal of the invention, however, the drive element also 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 transmission of the drive torque. There are many possibilities for the design of the positive locking element and the counter-positive locking element, whereby the possibilities known from the prior art can also be used within the scope of the invention. The positive locking element and the counter-positive locking element preferably 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 wave contour. The form-locking element and the counter-form-locking element preferably 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 angle of rotation position around the axis of rotation.

It may be desirable for the eccentric mass body to be secured in the starting position, which corresponds to the released coupling device. Such a securing in the starting position can be advantageous in order to avoid the eccentric mass body leaving the starting position for a removed rotor, which can then make it impossible or difficult to attach a new rotor. Any locking device or a spring (cf. the prior art mentioned at the beginning) can be used to secure the eccentric mass body in the starting position, to name just a few non-limiting examples. For a proposal of the According to the invention, the eccentric mass body is secured in a starting position by a magnet. For example, the drive element and the eccentric mass body can 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 help ensure that the eccentric mass body returns to the starting position after centrifugation has ended. The magnet and the securing effect brought about by the magnet are designed in such a way 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.

For 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 in the opposite direction to the eccentric mass body ramp surface and the rotor ramp surface, which means that the rotor with the rotor conical surface and rotor ramp surface is "caught" 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.

Alternatively, it is possible for the drive element cone surface and the eccentric mass body ramp surface to be "caught" between the rotor cone surface and the rotor ramp surface. For this design, the centrifugal force and the coupling force caused by this generate a contact force on the said cone surfaces and ramp surfaces, so that the rotor is axially clamped to the drive element.

While another arrangement is also possible, the invention proposes for a further proposal that the drive element cone surface and the rotor cone surface are arranged on the side facing away from the drive (i.e. for a vertical arrangement of the rotor axis with the drive below, above) of the eccentric mass body ramp surface and the rotor ramp surface. This enables a particularly compact, reliable and Durable design of the shaft-hub connection formed for holding the rotor and for the coupling device.

There are also a variety of options 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 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. This design preferably shifts the form-locking element and the counter-form-locking element away from the end region of the drive element arranged on the inside of 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, more material being available in the area of the drive element for the design and support of the form-locking element.

The rotor can form the functional surfaces explained for interaction with the drive element in any way, whereby the rotor can have 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. It is optionally possible for the insert sleeve to then also form the rotor cone surface.

There are also many different options for the design of the drive element, in particular the drive head, whereby the drive element is preferably made up of several parts. According to one proposal of the invention, the drive element has a base body. This base body preferably then forms the drive element conical surface. The drive element also 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. The eccentric mass body is then also guided along the guide track in the eccentric mass body receiving space. This guidance preferably takes place through 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 that is oriented parallel to the axis of rotation of the rotor. It is also possible for the base body and/or the cover body to have radially oriented ribs, via which the eccentric mass body can be guided (possibly in addition to the guide projection, the groove or the elongated hole), 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.

There are many different options for the shape of 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. It is possible, for example, that the centers of the inner surface and the outer surface of the circular ring segment are arranged offset from one another in the radial direction. For example, it is possible that the centers are arranged offset from one another by the displacement path of the eccentric mass body, which can result in a particularly compact embodiment.

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.

In addition to the connection and securing measures explained for fastening the rotor to the drive head, any other connection and/or securing measures can be used. For one proposal of the invention, the eccentric mass body has a locking element which interacts with a groove or undercut of the rotor. By means of the interaction, in particular an engagement of the locking element in the groove or behind the undercut, a positive locking can be ensured. Unlocking can take place, for example, when the vehicle is at a standstill as a result of the magnetic force of the magnets, by means of a manually operated unlocking mechanism or by means of a spring.

• Um lediglich einige Beispiele zu nennen, kann der Rotor einen Rotorrücksprung aufweisen, hinter den der Exzentermassekörper infolge der Zentrifugalkraft bewegt werden kann.
• Der Rotorrücksprung kann eine Rotor-Rampenfläche aufweisen, die in einem Halblängsschnitt unter einem Rampenflächenwinkel gegenüber einer Drehachse des Rotors geneigt ist, der kleiner ist als 45° (insbesondere kleiner ist 30° oder kleiner ist 25° oder kleiner ist als 20°).
• Der Rotor kann ein Gegen-Formschlusselement aufweisen, welches mit dem Formschlusselement des Antriebselements zur formschlüssigen Übertragung des Antriebsmomentes in Wechselwirkung tritt.
• Der Rotor kann eine Rotor-Konusfläche aufweisen, wobei die Rotor-Konusfläche entgegengesetzt zu der Rotor-Rampenfläche geneigt sein kann.
• Möglich ist, dass die Rotor-Rampenfläche weiter außenliegend, also in Richtung des Antriebs vorgeordnet, angeordnet sein kann als die Rotor-Konusfläche.
• Das Gegen-Formschlusselement des Rotors kann zwischen der Rotor-Konusfläche und der Rotor-Rampenfläche angeordnet sein.
• Der Rotor kann eine Einsatzhülse aufweisen, die die Rotor-Rampenfläche und/oder das Gegen-Formschlusselement und/oder die Rotor-Konusfläche ausbildet.

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 the centrifugal force.
• The rotor recess may have a rotor ramp surface which, in a semi-longitudinal section, is inclined at a ramp surface angle relative to a rotation axis of the rotor which is less than 45° (in particular less than 30° or 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 may have a rotor cone surface, wherein the rotor cone surface may be inclined opposite to the rotor ramp surface.
• It is possible that the rotor ramp surface can be arranged further outwards, i.e. further forward in the direction of the drive, than the rotor cone surface.
• The counter-form-locking element of the rotor can be arranged between the rotor cone surface and the rotor ramp surface.
• The rotor may have an insert sleeve which forms the rotor ramp surface and/or the counter-form-locking element and/or the rotor cone surface.

A further solution to the problem underlying the invention is represented by a drive head which is intended for a centrifuge as previously explained and is designed accordingly. The drive head has a centrifugal force-operated coupling device which has an eccentric mass body which is 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.

Advantageous developments of the invention emerge from the patent claims, the description and the drawings.

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

The following applies to the disclosure content - not the scope of protection - of the original application documents and the patent: Further features can be found in the drawings - in particular the geometries shown 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 of features of different patent claims is also possible in deviation from the selected references of the patent claims and is hereby suggested. This also applies to features that are shown in separate drawings or are mentioned in their description. These features can also be combined with features of different patent claims. Likewise, features listed in the patent claims can be omitted for further embodiments of the invention, but this does not apply to the independent patent claims of the granted patent.

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 number mentioned is present, without the need for an explicit use of the adverb "at least". For example, if an eccentric mass body or magnet is mentioned, 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 mentioned in the patent claims can be supplemented by further features or can be the only features that the subject matter of the respective patent claim has.

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 only the purpose of making the patent claims easier to understand.

BRIEF DESCRIPTION OF THE CHARACTERS

Fig. 1

zeigt ein als Antriebskopf ausgebildetes Antriebselement einer Laborzentrifuge in einer räumlichen Explosionsdarstellung.

Fig. 2

zeigt einen Rotor mit darin angeordnetem Antriebskopf gemäß Fig. 1 in einem räumlichen Halblängsschnitt, wobei die Kupplungseinrichtung gelöst ist.

Fig. 3

zeigt einen Längsschnitt durch den Rotor mit Antriebskopf gemäß Fig. 2.

Fig. 4

zeigt einen Längsschnitt durch den Antriebskopf gemäß Fig. 1, wobei die Kupplungseinrichtung in der gelösten Ausgangsstellung ist.

Fig. 5

zeigt den Antriebskopf gemäß Fig. 1 und 4 in der gelösten Ausgangsstellung in einer räumlichen Ansicht.

Fig. 6 bis 9

zeigen den Fig. 2 bis 5 entsprechende Darstellungen, wobei sich hier allerdings die die Kupplungseinrichtung in der gekuppelten Stellung befindet.

Fig. 10

zeigt eine weitere Ausführungsform eines Antriebkopfes mit dessen Annäherung an einen Rotor in einem Längsschnitt.

Fig. 11

zeigt den Rotor und den Antriebskopf gemäß Fig. 10 in einem räumlichen Halblängsschnitt.

Fig. 12 und 13

zeigen Ansichten gemäß Fig. 10 und 11, wobei hier aber die Kupplungseinrichtung die gelöste Ausgangsstellung verlassen hat und eine gekuppelte Stellung eingenommen hat.

Fig. 14

zeigt eine weitere Ausführungsform eines Antriebskopfes im Kupplungsbereich mit einem Rotor in einem Detail eines Halblängsschnitts.

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 a 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 starting position.

Fig. 5

shows 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 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.

Fig. 12 and 13

show views according to Fig. 10 and 11 , whereby 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

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.

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

The base body 4 forms a drive element conical surface 5 in the lower end area, which widens out from a cylindrical guide surface 6. Without this necessarily being 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.

The cover body 3 has a circular disk 10 which is placed on the star body 7 from above and is secured to the star body 7 by means of screws 11a, 11b, 11c. The screws 11a, 11b, 11c are screwed through holes 12a, 12b, 12c of the circular disk 10 to threaded holes 13a, 13b, 13c in the area of the ribs 8a, 8b, 8c. Three eccentric mass body receiving spaces 14a, 14b, 14c are formed between the cover body 3 and the base body, which are open radially outwards, are delimited radially inwards by the star sleeve 9 and are delimited in the circumferential direction by the ribs 8a, 8b, 8c.

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

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.

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.

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 cylinder segment. 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 sides of the circular ring segments 19 are oriented parallel to one another with a surface normal that is oriented parallel to the axis of rotation 39. The outer 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 an axis of rotation 39 with a ramp surface angle 22 that is preferably 15° +/- 5°.

Two guide projections 24, 25 each extend into the eccentric mass body receiving spaces 14, which for the embodiment shown are designed as guide bolts 26, 27 oriented parallel to the rotation axis 39. The guide bolts 26, 27 enter into radially oriented grooves or elongated holes on the underside of the eccentric mass body 18, the longitudinal axis of which is preferably oriented radially to the rotation axis 39. The engagement of the guide bolts 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 takes place in the radial direction to the rotation axis 39.

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.

If the cover body 3 is mounted with the base body 4, the eccentric mass bodies 18 are caught 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 axis of rotation 39, whereby the guide bolts 26, 27 cannot emerge from the grooves or elongated holes. The maximum movement path of the eccentric mass bodies 18 radially outwards is predetermined by the length of the grooves or elongated holes.

• eine kegelstumpfförmige Rotor-Konusfläche 31,
• eine zylindrische Führungsfläche 32,
• eine mit dem Rampenflächenwinkel 22 gegenüber der Drehachse 39 geneigte RotorRücksprung-Rampenfläche 33, die vorzugsweise im Bereich eines Rotorrücksprungs 40 des Rotors 23, der bspw. eine Hinterschneidung bilden kann, ausgebildet wird,
• einen zylindrischen Zwischenabschnitt 34, im Bereich dessen der Abdeckkörper 3 angeordnet ist und
• einen Abschnitt mit verringertem Durchmesser, in dem die Ausnehmung 30 das Gegen-Formschlusselement 35 ausbildet.

Fig. 2 shows a spatial 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 connected to one another:

• a truncated cone-shaped rotor cone surface 31,
• a cylindrical guide surface 32,
• a rotor recess ramp surface 33 inclined at the ramp surface angle 22 relative to the axis of rotation 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.

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 precise and form-fitting manner for the transmission of a drive torque in the counter-form-locking element 35.

Fig. 2 It 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.

In Fig. 2 the eccentric mass bodies 18 are in their starting position. In this starting position, the magnet 36 of the eccentric mass body 18 is arranged with the opposite pole adjacent to and aligned with the pole of the magnet 28, so that the starting position is secured via the magnetic force between the magnets 28, 36.

If the drive motor is activated, 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 body 18 with the eccentric mass body ramp surfaces 21 come into contact with the rotor ramp surfaces 33. The centrifugal forces acting in the contact surface thus generated are converted, as a result of the ramp surface angle 22, into an axial force which presses the base body 29 of the rotor 23 with the rotor cone surface 31 against the drive element cone surface 5.

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.

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 starting position. Fig. 6 to 9 an operating state of the coupling device 37 in which the eccentric mass bodies 18 are in the coupled position or securing position. If, after centrifugation has ended, it is desired to remove the rotor 23 from the drive head 2, the eccentric mass bodies 18 may well still be in the securing 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 as a result of 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.

In the Fig. 1 to 9 In the embodiment shown, guidance can be ensured by precisely fitting cylindrical contact surfaces between the guide surfaces 6, 32. It is also possible that in these areas there is no guidance via contact surfaces, but rather there is a play. 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.

For the Fig. 1 to 9 In the embodiment shown, 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 cone surface 5 and the rotor cone 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 13 another 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, in this case the drive element conical surface 5 and the rotor conical surface 21 being arranged furthest inside the rotor 23. This embodiment enables, for example, the form-locking element 15 and the counter-form-locking element 35 to have a larger diameter, so that an improved transmission of the drive torque is ensured. 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 take place in a material area 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, it is possible that this design enables more material to be made available in the area of the elements mentioned, which can result in improved strength.

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. In contrast, according to the embodiment in Fig. 10 to 13 these functional surfaces are at least partially formed by an insert sleeve 38, which can be inserted into the base body 29 and screwed to it. For the embodiment shown, the insert sleeve 38 forms both the rotor ramp surface 33 and the counter-form-locking element 35, while the rotor cone surface 31 is formed by the base body 29.

Preferably, the eccentric mass body ramp surfaces 21 are rounded in the region of the axial edges.

The coupling device 37 can be released in particular without tools by applying removal forces to the rotor 23. It is possible that after operation of the When the rotor 23 comes to a standstill in the centrifuge, the magnets 28, 36 automatically move the eccentric mass bodies 18 back 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.

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 made of aluminum or stainless steel.

• Möglich ist, dass die Führungsbahn 41 durch die Führung der Führungsvorsprünge 24, 25 in den Nuten oder Langlöchern der Exzentermassekörper 18 erfolgt. Vorzugsweise wird auf diese Weise eine Führung der Exzentermassekörper 18 in radialer Richtung gewährleistet und ein radial außenliegender oder radial innenliegender Anschlag für die Bewegung der Exzentermasse Körper 18 bereitgestellt.
• Möglich ist, dass die Führungsbahn 41 durch die Führung der Exzentermassekörper 18 zwischen der Unterseite des Abdeckkörpers 3 und der Oberseite des Grundkörpers 4 bereitgestellt wird. Diese Führung gewährleistet insbesondere, dass kein Verkanten der Exzentermassekörper 18 erfolgen kann und/oder keine Bewegung der Exzentermassekörper 18 in axialer Richtung erfolgen kann.
• Möglich ist des Weiteren, dass die Führungsbahn 41 gewährleistet wird von Kontaktflächen zwischen den Stirnseiten der Exzentermassekörper 18 in Umfangsrichtung und den Seitenflächen der Rippen 8 (für das dargestellte Ausführungsbeispiel ist dies nicht der Fall).

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 path 41 is provided by guiding the guide projections 24, 25 in the grooves or slots of the eccentric mass body 18. Preferably, in this way, guidance of the eccentric mass body 18 in the radial direction is ensured and a radially outer or radially inner stop is provided for the movement of the eccentric mass body 18.
• It is possible that the guide track 41 is provided by guiding the eccentric mass body 18 between the underside of the cover body 3 and the top of the base body 4. This guidance ensures in particular that the eccentric mass body 18 cannot become jammed and/or that the eccentric mass body 18 cannot move in the axial direction.
• 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 embodiment shown).

Deviating from the embodiments shown, 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.

Fig. 14 shows an embodiment in which a connection between the drive head 2 and the rotor 23 is not exclusively made and secured by the fact that the rotor 23 is clamped with the rotor cone surface 31 and the rotor ramp surface 33 between the eccentric mass body ramp surface 21 and the output element cone surface 5. Rather, an additional connection and securing is made 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 embodiment shown, the locking element 45 is directly connected 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, whereby a locked operating state is achieved. In the locked operating state, the locking element 45 and the groove or undercut 44 form a positive connection which blocks removal of the rotor 23 from the drive head 2 in a removal direction which corresponds to the direction of the axis of rotation 39.

The contact surfaces 46, 47 of the eccentric mass body 18 and the groove or undercut 44 can have any shape. For example, the contact surfaces 46, 47 can be designed as circular ring segment surfaces whose surface normal corresponds to the axis of rotation 39, or the contact surfaces 46, 47 can form any cone angle to the axis of rotation 39. Fig. 14 shows 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.

Unlocking can occur when, with the braking of the rotor 23, the force of the magnets 28, 36 on the eccentric mass bodies 18 becomes greater than the friction force component acting radially outward 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.

For the embodiment shown, 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 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.

REFERENCE SYMBOL LIST

1

drive element

2

drive head

3

cover body

4

base body

5

drive element conical surface

6

guide surface

7

stellar bodies

8

rib

9

star sleeve

10

circular disk

11

screws

12

drilling

13

threaded holes

14

eccentric mass body receiving space

15

form-fitting element

16

lateral surface

17

recess

18

eccentric mass body

19

circular ring segment

20

lateral surface

21

eccentric mass body ramp surface

22

ramp surface angle

23

rotor

24

lead

25

lead

26

guide pin

27

guide pin

28

magnet

29

base body

30

recess

31

rotor cone surface

32

guide surface

33

rotor ramp surface

34

intermediate section

35

counter-form-locking element

36

magnet

37

coupling device

38

insert sleeve

39

axis of rotation

40

rotor recess

41

guideway

42

guide surface

43

guide surface

44

groove, undercut

45

locking element

46

contact surface

47

contact surface

48

Nose

49

deepening

Claims (15)

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. Centrifuge according to claim 1, characterized in that the 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 rotation axis (39) of the rotor (23) which is less than 45°, in particular less than 30° or less than 25° or less than 20°. 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. 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). 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) distributed over the circumference. Centrifuge according to one of the preceding claims, characterized in that the 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. Centrifuge according to one of the preceding claims, characterized in that the eccentric mass body (18) is secured in an initial position via a magnet (28, 36). 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 cone surface (5) and the rotor cone surface (31) are inclined opposite to the eccentric mass body ramp surface (21) and the rotor ramp surface (33), wherein preferably the drive element cone surface (5) and the rotor cone 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). 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) 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) are arranged. 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 cone surface (31). Centrifuge according to one of the preceding claims, characterized in that the 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. Centrifuge according to one of the preceding claims, characterized in that the eccentric mass body (18) is designed as a circular ring segment (19). 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). 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 rotation axis (39) of the rotor (23) which is less than 45°, in particular less than 30° or less than 25° or less than 20°. 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.

Images