Centrifuge

Abstract

The invention relates to a centrifuge (1) having a rotor (2) which is mounted in a centrifuge housing so as to be rotatable about an axis of rotation, wherein the rotor (2) has receptacles for sample containers, a motor having a motor shaft, an axial guide between the rotor (2) and the motor shaft, a first surface associated with the rotor (2), and a second surface associated with the motor shaft, and pressing means, characterised in that magnet elements (8, 9, 9') are provided as pressing means between the rotor and the motor shaft, the magnetic field of which magnet elements creates an attractive force between the surfaces, and wherein the torque transmission is formed by a friction coupling between the rotor (2) and motor shaft, wherein a friction coupling is formed by the first and the second surface and wherein the pressing means, in the coupled state of the friction coupling, exerts a closing force on the friction coupling and / or torque transmission is ensured by the magnetic field of the magnet elements (8, 9, 9').

Description

[0001] centrifuge

[0002] Description

[0003] The present invention relates to a centrifuge comprising a rotor rotatably mounted in a centrifuge housing about an axis of rotation, a motor, an axial guide, a friction clutch and pressure means.

[0004] Centrifuges are used to separate the components of samples contained in sample containers by rotating a rotor at high speed. It is essential to be able to couple the rotor and motor shaft of the centrifuge with the most precise centering possible in a simple manner. Currently, at least the initial axial forces required for torque transmission are applied by a manually operated spring-loaded locking mechanism. This results in wear on the moving mechanical parts and a risk of operator error leading to insufficient locking. Centrifuges known from the prior art feature locking mechanisms that are generally cumbersome to operate, resulting in time-consuming locking and unlocking processes, and often cannot be released with one hand.

[0005] Solutions are known in the art in which the conical surfaces of centrifuges are axially pre-tensioned against each other by spring elements, so that the required drive torques can be transmitted via the conical surfaces pressed together under the spring force. It is also known to increase the contact forces by means of centrifugal weights, so that a higher drive torque can be transmitted at high speeds. DE 10 2012 011 531 B4 discloses a centrifuge that has a locking mechanism for closing the centrifuge. The locking mechanism serves both to securely connect several individual parts of a centrifuge set and to transmit torque from a drive shaft to a rotor.

[0006] The object of the present invention is therefore to provide a centrifuge in which the coupling of the rotor to the motor shaft can be simplified, but still be carried out in a completely reliable manner.

[0007] This problem is solved by the subject matter of the independent patent claim. Advantageous embodiments and further developments are the subject of the dependent claims, the accompanying description, and the figures.

[0008] According to the invention, a centrifuge is provided which has a rotor rotatably mounted about an axis in a centrifuge housing. This rotor has receptacles suitable for receiving and holding sample containers during centrifugation. The centrifuge also includes a motor with a motor shaft for driving the rotor. An axial guide is arranged between the rotor and the motor shaft. Furthermore, a first surface associated with the rotor and a second surface associated with the motor shaft are provided, as well as pressure elements. Magnetic elements are provided as pressure elements between the rotor and the motor shaft, the magnetic field of which generates an attractive force between the surfaces.The magnetic elements can be either magnets or magnetizable elements, so it is also conceivable that not several magnets are combined as pressure means, but rather, for example, a single magnet with a magnetizable element such as an iron plate, which advantageously increases the range of applications. Torque transmission at the centrifuge is achieved either via a friction clutch formed between the rotor and the motor shaft. The friction clutch is formed by the first surface, associated with the rotor, and the second surface, associated with the motor shaft. The second surface, associated with the motor shaft, preferably comes into contact with the first surface by being arranged to engage it over a surface area. In the engaged state of the friction clutch, the pressure means exert a closing force on the friction clutch.Additionally, a further axially detachable positive locking connection (in the circumferential direction) can be provided to ensure torque transmission.

[0009] Instead of a friction clutch, only an axial stop can be provided. The axial guide and radial stop can then be combined into a conical guide.

[0010] Alternatively or additionally, the transmission of torque can be ensured by the magnetic field of the magnetic elements. The attractive force of the magnets in the axial direction is preferably dimensioned so that its magnitude is greater than any potential lift forces of the rotor (minus the force of gravity) that may arise from aerodynamic lift due to the rotor shape. The use of a friction clutch can be advantageous because it allows for the limitation of momentary torque peaks, whereas a magnetic clutch is low-wear. A combination of both can combine their advantages and increase functionality. The pressure means can provide a locking mechanism between the two surfaces, thus ensuring the proper operation of the centrifuge without the risk of an unintended separation of the two surfaces leading to an opening during operation.This attractive force is preferably reversible, so that a deliberate separation of the two surfaces from each other is easier to carry out, for example to open the centrifuge and to remove or introduce samples.

[0011] The motor shaft preferably includes a drive head that is inserted into a hub of the rotor. The hub is then designed to transmit the motor's driving force to the rotor via a drive shaft connected to the drive head. The hub and rotor can be designed as separate, connectable components or as a single piece.

[0012] By providing a preferred magnet pairing to generate axial forces acting on the first surface associated with the rotor and a second surface associated with the motor shaft, coupling in the centrifuge can be achieved simply by inserting the rotor. The frictional torques required at least for the starting torque on the first and second surfaces are provided by the magnetic forces of the magnet elements. These magnetic forces replace the tension forces previously applied by spring elements and are supported by the rotor's own weight. This design is particularly simple and user-friendly, as locking elements are unnecessary, at least when inserting the rotor. The absence of locking elements reduces the number of parts, thereby minimizing wear. The magnet elements can be positioned at any location that allows for the generation of axial forces.

[0013] According to one embodiment, the first and second surfaces are designed as conical surfaces. This is advantageous for ensuring optimal centrifugal function through consistent guidance within the drive unit. This design allows the torque to be transmitted via the contact force on the conically shaped area. Furthermore, it is necessary to easily couple the rotor and motor shaft with perfect centering, for which conical surfaces are ideally suited because they are self-centering as soon as they are placed against each other. This design is also particularly suitable for ensuring smooth rotation of the centrifuge. However, other shapes are also conceivable.

[0014] According to another embodiment, a movable release element is provided for mechanical unlocking, which facilitates separating the rotor and the motor shaft. The release element can, for example, be designed to be pressed against the motor shaft to push it out of the rotor hub. This makes removing the rotor easier because less force is required. Thus, unlocking and opening the centrifuge can be easily done with one hand by actuating the release element and then pulling the rotor off the centrifuge.

[0015] According to a further embodiment, a movable release element is provided for unlocking, which is suitable for weakening the magnetic field of the magnetic elements. Preferably, the magnetic element provided on the rotor has a recess, and the release element has a oppositely polarized magnetic element that can be moved into this recess. As soon as the oppositely polarized magnetic element of the release element is in the recess, it weakens the magnetic field of the magnetic element, thus facilitating removal. This advantageously prevents vibrations of the sample that could otherwise cause separated components to mix again within the sample container.

[0016] According to another embodiment, a spring is provided to pre-tension the release element. The spring force can be used to move the release element into a desired position and return it to that position repeatedly. This facilitates unlocking by utilizing the restoring force from the spring to perform the unlocking action and separate the parts. As a result, less force is required to remove the rotor because the spring force provides assistance. This is advantageous for enabling one-handed unlocking.

[0017] According to another embodiment, the spring is arranged on the release element or between the motor shaft and the release element. If the spring is arranged on the release element, it can be designed to pull the release element away from the motor shaft or rotor. For example, if the release element includes a polarized magnet element that can be inserted into the recess of the rotor's magnet element, the spring should be dimensioned so that its spring force is sufficiently high to remove the polarized magnet element from the recess. Because of its polarity being reversed compared to the rotor's magnet element, the rotor remains stable precisely in the center. If the spring is arranged between the motor shaft and the release element, it is conceivable, for example, that it could be located on or even in the head region, i.e., a drive head of the motor shaft.Then it is effective in pushing the release element away from the rotor and the motor shaft. If the release element also includes a magnetic element with opposite polarity to weaken the magnetic field of the magnetic element associated with the rotor, then, due to this arrangement, the spring does not have to press against both the spring and the magnetic repulsion when inserting the release element, but only against the magnetic repulsion.

[0018] According to another embodiment, the release element is designed as an axially movable push pin. Such a push pin has the advantage that it can be easily operated with one hand and requires very little installation space. The push pin can also be easily connected to a spring, for example, by simply sliding the spring onto it.

[0019] According to another embodiment, a stop ensures a distance between the magnetic elements when locked. For the centrifuge's long-term durability, the long service life of all individual parts is crucial. A stop prevents the magnetic elements from coming into direct contact. Such contact could damage them and impair their function, which is why it must be avoided at all costs.

[0020] According to another embodiment, the magnet pair is positioned above the conical surfaces in the head region of the motor shaft and a corresponding area of ​​the rotor. This allows for a space-saving and centrally located arrangement. The release mechanism can thus be positioned precisely in the center of the centrifuge, which is particularly advantageous when it is to be opened with one hand.

[0021] According to another embodiment, the magnet pair is positioned below the cone surfaces. For example, magnet pairs can be arranged on opposite sides outside the cone surfaces. This allows the distance between the magnet pairs to be as large as possible, thereby increasing the holding force. Furthermore, this allows for the transmission of more torque. It would also be conceivable to provide a ring-shaped magnet pair circumferentially below the cone to further increase the holding force.

[0022] According to another embodiment, additional elements are provided to increase the closing force. For example, centrifugal force elements can be used at higher rotational speeds, or an increased weight force can be applied. This can have a beneficial effect on the locking mechanism of the centrifuge and increase operational reliability.

[0023] Further features, details and advantages of the invention will become apparent from the wording of the claims as well as from the following description of exemplary embodiments based on the drawing.

[0024] They show:

[0025] Figure 1: An exemplary embodiment depicting a centrifuge in schematic representation;

[0026] Figure 2: Another embodiment showing a centrifuge;

[0027] Figure 3a: Another embodiment depicting a centrifuge in schematic representation in the locked state;

[0028] Figure 3b: the arrangement according to Figure 3a in the unlocked state;

[0029] Figure 4a: Another embodiment depicting a centrifuge in schematic representation in the locked state; and

[0030] Figure 4b: the arrangement according to Figure 4a in the unlocked state.

[0031] Figure 1 shows a schematic representation of an embodiment of a centrifuge 1. The centrifuge has a cylindrical shape suitable for radial and axial guidance, and optionally a conical shape extending from it. This design enables torque transmission through the contact force on the conically shaped section. However, it would also be conceivable to provide an axial stop between the rotor 11 and the motor shaft in another embodiment. A magnetic element 8 in the form of a magnet is provided in an end face 14 of a drive head 3. A magnetic element 9 in the form of a magnet is arranged in a hub 2 of a rotor 11. The axial attraction of the magnetic elements 8, 9 is preferably dimensioned such that its magnitude is greater than any potential lift forces of the rotor (minus the force of gravity). Lift forces arise from the aerodynamic lift caused by the rotor shape.The drive head 3 comprises a first conical surface 7, while the hub 2 of the rotor has a second conical surface 6. The magnetic element 9 and the magnetic element 8 are arranged parallel to each other. It is also conceivable to provide a magnetizable plate as the magnetic element 8 instead of a magnet, or to provide a magnetizable plate instead of the magnet in the form of the magnetic element 9, as long as one of the two remains a magnetic element 8, 9. The magnetic element 8 and the magnetic element 9 do not touch each other. This prevents them from colliding when the rotor 11 is placed on the drive head, which could lead to breakage of the magnetic elements 8, 9. In this embodiment, a push pin 4 is provided to simplify removal. The push pin 4 can be guided through a recess 12 in the magnetic element 9 and is movable against the drive head 3 for removal.The pressure pin 4 has a spring 5 on the side facing away from the drive head 3, which allows the pressure pin 3 to return to its original position.

[0032] To detach the rotor 11 from the centrifuge 1, it can be pulled until the magnetic force of the magnetic elements 8, 9 is overcome. The locking mechanism can be released more easily by simultaneously pulling on the rotor 11 and pressing the push pin 4. This pushes the drive head 3 out of the hub 2 of the rotor 11 with the help of the push pin 4, which presses against its end face 14. Less force is then required to pull on the rotor 11, making its removal easier. This allows the centrifuge 1 to be opened with one hand, without having to overcome any complex locking mechanisms beforehand.

[0033] Figure 2 shows a further embodiment of a centrifuge 1 in schematic form. Magnetic elements 9 are arranged on the outer surface of the hub 2 of the rotor 11, the surface facing away from the drive head 3. Opposite these, magnetic elements 8 are positioned in the drive head. The magnetic elements 8 and 9 are also arranged outside the conical surfaces 6 and 7. The resulting comparatively larger area over which the magnetic force is distributed allows for the generation of greater holding force and the transmission of more torque when required. To release the locking mechanism, the rotor 11 can be pulled and removed from the centrifuge 1.

[0034] It is also conceivable to provide the locking mechanism by means of a oppositely polarized magnetic element 9', as shown in Figures 3a, b and 4a, b. Figures 3a and 4a each show the centrifuge 1 in the locked state, while Figures 3b and 4b show the unlocked state. The magnetic element 9 is arranged inside the hub of the rotor 11. Opposite the rotor, the drive head 3 includes a magnetic element 8 on its end face 14, in this embodiment designed as a magnetizable plate. The magnetic element 9 has a recess 12 through which the oppositely polarized magnetic element 9', attached to the push pin 4, can be guided. The push pin includes a retaining element 10. The magnetic element 9' is arranged on the side of the retaining element 10 facing the drive head 3.In Figures 3a and 3b, the spring 5 is arranged on the side of the retaining element 10 opposite the magnetic element 9', and a restoring force can be generated with it. To release the rotor 11, the pressure pin 4 can be pressed against the spring 5 and pushed towards the drive head 3. As soon as the magnetic element 9' is pushed into the recess 12, it weakens the magnetic field of the magnetic element 9, thereby reducing the adhesion of the magnetic element 8, which is designed as a magnetizable plate, and facilitating the removal of the rotor 11. A repulsive-adherent-sliding effect may occur during unlocking, but it can be overcome with minimal force. Additionally, some residual removal pressure may need to be overcome, but this is also negligible, so that unlocking can still be performed with just one hand.

[0035] Figures 4a and 4b show an embodiment in which the spring 5 is located on the end face 14 of the drive head 3. The spring can be located on or within the drive head 3 and only needs to be effective during the last few millimeters of the push pin 4's movement to push it back out of the recess 12. This arrangement eliminates the need to push against spring force and magnetic repulsion at the start of the push. Consequently, less force is required for unlocking. The push pin 4 would then only be pushed out of the drive head 3 when the rotor 11 is next placed on it. Therefore, its further protrusion from the retaining element 10 compared to the unlocked state could serve as an indicator of secure locking.

[0036] Reference symbol list

[0037] 1 centrifuge

[0038] 2 Hub 3 Drive head

[0039] 4 pressure pen

[0040] 5 springs

[0041] 6 First cone surface

[0042] 7 Second cone surface 8 Magnetic element

[0043] 9, 9' magnetic elements

[0044] 10 retaining elements

[0045] 11 Rotor

[0046] 12 Recess 14 Front side

Claims

Patent claims 1. Centrifuge (1) having • a rotor (2) which is rotatably mounted in a centrifuge housing about an axis of rotation, wherein the rotor (2) has receptacles for sample containers, • a motor with a motor shaft; • an axial guide between rotor (2) and motor shaft; • a first surface associated with the rotor (2) and a second surface associated with the motor shaft; and • Pressure means; characterized in that magnetic elements (8, 9, 9') are provided as pressure means between the rotor and the motor shaft, the magnetic field of which creates an attractive force between the surfaces and wherein the torque transmission is achieved by • a friction clutch is formed between rotor (2) and motor shaft, wherein a friction clutch is formed by the first and the second surface and wherein the pressure means exert a closing force on the friction clutch in the coupled state of the friction clutch; • and / or is ensured by the magnetic field of the magnetic elements (8, 9, 9').

2. Centrifuge (1) according to claim 1 , characterized in that the first surface and the second surface are designed as conical surfaces (6,7).

3. Centrifuge (1) according to claim 1 or 2, characterized in that a movable unlocking element is provided for mechanical unlocking, which facilitates the separation of the rotor (2) and the motor shaft from each other.

4. Centrifuge (1) according to claim 1 or 2, characterized in that a movable unlocking element is provided for unlocking, which is suitable for weakening a magnetic field of the magnetic elements (8).

5. Centrifuge (1) according to one of claims 3 or 4, characterized in that a spring (5) is provided for pre-tensioning the unlocking element.

6. Centrifuge (1) according to claim 5, characterized in that the spring (5) is arranged on the unlocking element or between the motor shaft and the unlocking element.

7. Centrifuge (1) according to one of claims 3 to 6, characterized in that the unlocking element is designed as an axially movable pressure pin (4).

8. Centrifuge (1) according to one of claims 1 to 7, characterized in that a stop is provided which ensures a distance between the magnetic elements in the locked state.

9. Centrifuge (1) according to claim 2 and preferably one of claims 3 to 8, characterized in that the position of the magnet pairing of the magnet elements (8,9) is provided above the conical surfaces (6,7) in the head region of the motor shaft and a corresponding region of the rotor (2).

10. Centrifuge (1) according to claim 2 and preferably one of claims 3 to 8, characterized in that the position of the magnet pairing of the magnet elements is provided below the cone surfaces (6,7).

11. Centrifuge (1) according to one of claims 1 to 10, characterized in that additional elements are provided to increase the closing force.

Images