EP1329263A1 - Rotor with cavities for receiving a product for centrifuging and corresponding centrifuge - Google Patents

Abstract

The geometry of at least one seating (81) rotating about the axis of rotation in a first direction of rotation and angle 360 degrees/n is distinct from a second seating (101) which follows the first directly in the first direction of rotation. A rotor (1) is of the type designed to be driven in rotation around a central rotating axle (A) and has a number of seatings (81, 101) for a product to be centrifuged. The seatings are eccentric relative to the axis of rotation. The seatings are invariant by geometric rotation about the axis of rotation and by an angle greater than 360 degrees/n where n is an even number greater than or equal to 4 and the seatings are symmetrical in pairs about the axis of rotation. The seatings have an elongated shape along a longitudinal direction D and the second seating is the image of the first by a geometric transformation, comprising rotation through an angle alpha (not zero) in a plane orthogonal to the axis of rotation, and/or rotation through an angle beta (not zero) in a plane containing the axis of rotation and the longitudinal direction of the first seating and/or a translation through a distance d (not zero) in a plane orthogonal to the axis of rotation and/or a translation through a distance delta (not zero) in a plane containing the axis of rotation and the longitudinal direction of the first seating. An Independent claim is also included for a centrifuge comprising a vessel, a rotor as above designed to fit into the vessel and a device for driving the rotor in rotation.

Description

The present invention relates to a rotor of the type intended to be driven in rotation about a central axis of rotation and in which a number n of housings for receiving a product to be centrifuged are provided, the housings being eccentric relative to the rotation axis.

The invention applies, for example, to the centrifugation of products organic.

For centrifugation of such products, generally used tapered rotors in which the housings have been formed in the form of recesses. These housings have elongated shapes and are, for each rotor, regularly distributed around its axis of rotation. These housings are intended to receive, for example, tubes containing the products to be centrifuged and closed with caps.

A centrifuge using such a rotor generally comprises a tank, provided with refrigeration means and in which the rotor is mounted on a rotating drive head.

It has been found in ultracentrifuges, i.e. centrifuges driving the rotors at speeds of the order of 20,000 rpm, the appearance of noise pollution such as hissing.

An object of the invention is to solve this problem by limiting the noise pollution caused by rotating rotors of the type supra.

To this end, the subject of the invention is a rotor of the aforementioned type, characterized in that the geometric image of at least one first housing, by a geometric rotation around the axis of rotation in a first direction of rotation and angle 360 ° / n , is distinct from a second housing which directly follows the first housing in the first direction of rotation.

• les logements sont invariants par une rotation géométrique autour de l'axe de rotation et d'angle strictement supérieur à 360° / n,
• n est un nombre pair supérieur ou égal à 4 et les logements sont symétriques par paires par rapport à l'axe de rotation,
• les logements ont une forme sensiblement analogue allongée suivant une direction longitudinale respective et le deuxième logement est sensiblement l'image par une transformation géométrique de l'image géométrique du premier logement,
• la transformation géométrique comprend une rotation géométrique d'un angle non nul dans un plan orthogonal à l'axe de rotation,
• la transformation géométrique comprend une rotation géométrique d'un angle non nul dans un plan contenant l'axe de rotation et la direction longitudinale de l'image géométrique du premier logement,
• la transformation géométrique comprend une translation géométrique d'une distance non nulle dans un plan orthogonal à l'axe de rotation,
• la transformation géométrique comprend une translation géométrique d'une distance non nulle dans un plan contenant l'axe de rotation et la direction longitudinale de l'image géométrique du premier logement.

According to particular embodiments, the rotor may include one or more of the following characteristics, taken alone or in any technically possible combination:

• the housings are invariant by a geometric rotation around the axis of rotation and an angle strictly greater than 360 ° / n ,
• n is an even number greater than or equal to 4 and the housings are symmetrical in pairs with respect to the axis of rotation,
• the housings have a substantially similar shape elongated in a respective longitudinal direction and the second housing is substantially the image by a geometric transformation of the geometric image of the first housing,
• the geometric transformation comprises a geometric rotation of a nonzero angle in a plane orthogonal to the axis of rotation,
• the geometric transformation comprises a geometric rotation of a non-zero angle in a plane containing the axis of rotation and the longitudinal direction of the geometric image of the first housing,
• the geometric transformation comprises a geometric translation of a non-zero distance in a plane orthogonal to the axis of rotation,
• the geometric transformation comprises a geometric translation of a non-zero distance in a plane containing the axis of rotation and the longitudinal direction of the geometric image of the first housing.

The invention further relates to a centrifuge comprising a tank, a rotor intended to be placed in the tank, and means rotor rotation drive, characterized in that the rotor is a rotor as defined above.

• la figure 1 est une vue schématique latérale d'une centrifugeuse selon l'invention,
• la figure 2 est une vue schématique du dessus du rotor de la figure 1,
• les figures 3 et 4 sont des vues analogues à la figure 2 illustrant respectivement un deuxième et un troisième modes de réalisation du rotor,
• la figure 5 est une vue schématique, agrandie et en coupe du rotor de la figure 4, prise suivant la ligne brisée V-V,
• la figure 6 est une vue analogue à la figure 5 illustrant un quatrième mode de réalisation du rotor,
• la figure 7 est une vue analogue à la figure 2 illustrant un cinquième mode de réalisation du rotor, et
• la figure 8 est une vue analogue à la figure 5 illustrant un sixième mode de réalisation du rotor.

The invention will be better understood on reading the description which follows, given only by way of example, and made with reference to the appended drawings, in which:

• FIG. 1 is a schematic side view of a centrifuge according to the invention,
• FIG. 2 is a schematic view from above of the rotor of FIG. 1,
• FIGS. 3 and 4 are views similar to FIG. 2 respectively illustrating a second and a third embodiment of the rotor,
• FIG. 5 is a diagrammatic view, enlarged and in section of the rotor of FIG. 4, taken along the broken line VV,
• FIG. 6 is a view similar to FIG. 5 illustrating a fourth embodiment of the rotor,
• FIG. 7 is a view similar to FIG. 2 illustrating a fifth embodiment of the rotor, and
• Figure 8 is a view similar to Figure 5 illustrating a sixth embodiment of the rotor.

Figures 1 and 2 schematically illustrate a centrifuge 1 which comprises a tank 2, a rotor 3 disposed in the tank 2, and means 4 for rotating the rotor 3 around an axis of rotation A substantially vertical.

Conventionally, the tank 2 comprises a movable access door 6 and means for refrigerating its interior atmosphere, which means are not shown in the figures.

The rotor 3 is a generally frustoconical rotor with a central axis A. It is equipped with a removable closure cover 7. Cover 7 has not been shown in figure 2.

The rotor 3 is for example made of metal and four housings offset from the axis A are formed there, namely a first pair of housings 8 ₁ and 8 ₂ and a second pair of housings 10 ₁ and 10 ₂ . It will be noted that the housings 10 ₁ and 10 ₂ are not shown in FIG. 1.

The housings 8 ₁ and 8 ₂ of the first pair are symmetrical to each other with respect to the axis A. The housings 10 ₁ and 10 ₂ of the second pair are symmetrical to each other with respect to to axis A.

The housings 8 ₁ , 8 ₂ , 10 ₁ and 10 ₂ have a similar shape elongated along a respective longitudinal direction D.

As can be seen in FIG. 1 for the housings 8 ₁ and 8 ₂ , each direction D is inclined relative to the axis of rotation A and cuts it at a geometric point located above the rotor 3 and its cover 7 .

The housings 8 ₁ , 8 ₂ , 10 ₁ and 10 ₂ open into the upper surface 12 of the rotor to allow, when the cover 7 is removed, to introduce into the housings containers containing the product or products to be centrifuged, for example tubes closed by caps.

In FIG. 1, the distance separating the housings 8 ₁ , 8 ₂ , 10 ₁ and 10 ₂ from the external lateral surface 14 of the rotor 3 has been exaggerated to facilitate the representation.

As can be seen in FIG. 2, the distribution of the housings 8 ₁ , 8 ₂ , 10 ₁ and 10 ₂ around the axis of rotation A is irregular.

If such a distribution were regular, the rotor 3 would be invariant by a geometric rotation of axis A and angle equal to 90 ° (π / 2 rad). Thus, the geometric image I (in double-dashed dashed line) of the housing 8 ₁ by such a rotation in a first direction S ₁ would be confused with the housing 10 ₁ , housing which directly follows the housing 8 ₁ in this direction S ₁ .

In the rotor of FIGS. 1 and 2, the housing 10 ₁ is not confused with this image I but is, in top view, angularly offset from this image I by a non-zero angle α centered on the axis A and negative with respect to the direction S ₁ .

In other words, the housing 10 ₁ is the image, by a geometric rotation of axis A and of angle α, of the image I.

Thus, the longitudinal directions D of the housings 10 ₁ and of the image I form a top view of an angle α centered on the axis A and negative when considering the direction S ₁ .

The angle α is for example 4 ° and can be understood more generally between 2 ° and 10 °.

Note that in Figure 2, the amplitude of the angle α has been exaggerated to facilitate representation.

Likewise, the housing 10 ₂ is angularly offset, in plan view, from the image not shown of the housing 8 ₂ by the aforementioned rotation.

Thus, the housings 8 ₁ , 8 ₂ , 10 ₁ and 102 are invariant by a geometric rotation of axis A and of angle equal to 180 ° (π rad) but not by a rotation of axis A and of angle equal to 90 ° (π / 2 rad) as in the state of the art.

It was found, when one rotates the rotor 3 to relatively high speeds, typically greater than 10,000 rpm, than noise pollution such as whistling is greatly reduced, or even deleted.

It is currently estimated that the reason for this reduction or elimination of noise pollution may be as follows. When the rotor 3 is rotated, the zones Z (Figure 1) of the outer lateral surface 14 of the rotor 3 located radially opposite the housings 8 ₁ , 8 ₂ , 10 ₁ and 10 ₂ deform, under the effect of the centrifugal force, radially outward more strongly than the areas of the outer lateral surface 14 located between the housings. The reliefs thus created on the surface 14 are, like the housings 8 ₁ , 8 ₂ , 10 ₁ and 10 ₂ , invariant by a geometric rotation of axis A and of angle equal to 180 ° (π rad), and not by a geometric rotation of axis A and angle equal to 90 ° as in the state of the art. Thus, the frequencies and intensities of the acoustic waves created during the rotational drive of the rotor are modified and the noise pollution reduced, or even eliminated.

In addition, the imbalances caused by the irregularity of layout dwellings are relatively small and acceptable thanks to the fact that α is relatively small.

According to a variant of the embodiment of FIGS. 1 and 2, the angle α can be positive with respect to the direction S ₁ .

More generally, other arrangements of the housing 8 ₁ , 8 ₂ , 10 ₁ and 10 ₂ are conceivable.

Thus, in the embodiment of FIG. 3, the housing 10 ₁ is viewed from above laterally translated, with respect to the image I of the housing 8 ₁ , opposite the direction S ₁ of a distance d not nothing. Thus the longitudinal directions D of the housing 10 ₁ and of the image I of the housing 8 ₁ are substantially parallel and spaced laterally from one another.

The distance d is for example 2mm and can more generally be between 1 and 5mm.

Note that in Figure 3 the distance d has been exaggerated.

This distance being relatively small, the difference between the centrifugation forces to which the products received in the housings 8 ₁ , 8 ₂ , 10 ₁ and 10 ₂ will remain sufficiently small and acceptable for the homogeneity of the centrifugation treatment. Likewise, the imbalances caused by the irregularity of layout remain acceptable.

According to a variant not shown, the housing 10 ₁ can be, in top view, offset laterally from the image I of the housing 8 ₁ in the direction S ₁ .

More generally, the housing 10 ₁ can be, in top view, resulting from a geometric translation of the image I, the direction of this translation not necessarily being orthogonal to the direction D of the image I.

Even more generally, the housing 10 ₁ can be deduced from the image I of the housing 8 ₁ by a geometric transformation in a radial plane containing the axis of rotation A and the longitudinal direction D of the image I.

Thus, FIGS. 4 and 5 illustrate a third embodiment in which the longitudinal direction D of the housing 10 ₁ is angularly offset by a non-zero angle β relative to the longitudinal direction D of the image I in the above-mentioned plane P ( figure 4). This plane P also contains the direction D of the housing 10 ₁ and corresponds to the right half-plane of FIG. 5. Thus, the housing 10 ₁ is the image, by a geometric rotation of angle β in the plane P, of the image I.

Note that the angle β can be positive or negative. This angle β a by example a value of 4 ° and can be more generally between 2 ° and 10 °.

FIG. 6 illustrates another embodiment in which the housing 10 ₁ is obtained from image I by geometric translation of a substantially constant distance δ not zero in the radial plane P. Thus the directions D of the housing 10 ₁ and of image I are substantially parallel and spaced from each other. The aforementioned translation can be such that the housing 10 ₁ is closer or more distant from the outer lateral surface 14 than the image I.

It will be noted that in FIGS. 5 and 6 the angle β and the distance δ have been exaggerated.

It will also be noted that the angle β or the distance δ are sufficiently small so that on the one hand the homogeneity of the centrifugation treatment undergone by products received in the housings 8 ₁ , 8 ₂ , 10 ₁ and 10 ₂ is satisfactory and on the other hand the unbalances are reduced.

More generally, the above principles can be applied to rotors comprising any number of housings.

They can also be combined with each other for the same housing.

Thus, FIG. 7 illustrates yet another embodiment where the housing 10 ₁ is the image by a geometric transformation of the image I, this geometric transformation comprising a geometric rotation and a geometric translation in the plane of FIG. 7 which is orthogonal to the axis of rotation A.

More precisely, the rotation is a rotation of axis A and of angle α.

The translation is a translation in the plane of Figure 7 of a non-zero distance d in a direction which is not orthogonal to the direction D of image I.

The combination of rotation and translation within the geometric transformation allows the housing 10 ₁ to remain sufficiently close to image I to limit the differences between the centrifugation force undergone by a product contained in the housing 10 ₁ and the centrifugation force of a product received in the housing 8 ₁ .

Thus, the homogeneity of the centrifugation treatment undergone by products received in the housings 8 ₁ , 8 ₂ , 10 ₁ and 10 ₂ is increased. In addition, this combination makes it possible to reduce the imbalances as well as the difference in appearance between a rotor incorporating the principles of the invention and a conventional rotor.

Similarly, FIG. 8 illustrates another embodiment in which the housing 10 ₁ is obtained from image I by a geometric transformation comprising a geometric rotation and a geometric translation in the radial plane P which comprises the axis of rotation A and the longitudinal direction D of image I.

More precisely, the rotation is a non-zero angle β rotation and the translation a translation of a non-zero distance δ in one direction orthogonal to axis A.

Here again, the combination of a translation and a rotation makes it possible to increase the homogeneity of the centrifugation treatment undergone by products received in the housings 8 ₁ , 8 ₂ , 10 ₁ and 10 ₂ , to limit unbalances and to reduce aesthetic inconvenience.

More generally, the geometric transformation between the image I and the housing 10 ₁ may comprise a translation and / or a rotation in a plane orthogonal to the axis of rotation A, and a translation and / or a rotation in a radial plane containing axis A.

Also generally, the translations and rotations described previously can be applied, for example separately each to a respective pair of dwellings when the number of dwellings is even and strictly greater than 4.

Preferably, the housings are symmetrical in pairs with respect to the axis A. Thus, when the rotor 3 is provided with an even number n of housings, the rotor 3 will be invariant by a geometric rotation of axis A and of 180 ° angle which limits imbalances. More generally, an invariance by a geometric rotation of axis A and an angle strictly greater than 360 ° / n will make it possible to limit the imbalances.

To avoid the appearance of noise pollution, it will always exist at minus a first housing whose geometric image, by a rotation geometric around the axis of rotation A and angle 360 / n in one direction rotation, is distinct from a second housing of the rotor, this second housing directly following the first housing in the chosen direction of rotation.

Claims (6)

Rotor (3) of the type intended to be rotated about a central axis of rotation (A) and in which a number n of housings (8 ₁ , 8 ₂ , 10 ₁ , 10 ₂ ) for receiving a product to be centrifuged are provided, the housings being eccentric with respect to the axis of rotation, characterized in that the geometric image (I) of at least one first housing (8 ₁ ), by a geometric rotation about the axis of rotation (A) in a first direction of rotation (S ₁ ) and of angle 360 ° / n , is distinct from a second housing (10 ₁ ) which directly follows the first housing (8 ₁ ) in the first direction of rotation (S ₁ ), in that the housings (8 ₁ , 8 ₂ , 10 ₁ , 10 ₂ ) have a substantially similar shape elongated in a respective longitudinal direction (D) and in that the second housing (10 ₁ ) is substantially the image by a geometric transformation of the geometric image (I) of the first housing (8 ₁ ), and in that the geometric transformation comprises d a geometric rotation of a non-zero angle (α) in a plane orthogonal to the axis of rotation (A) (Figures 2 and 7) and / or a geometric translation of a non-zero distance ( d ) in a plane orthogonal to the axis of rotation (A) (Figures 3 and 7), the direction of this translation being inclined relative to the longitudinal direction (D) of the geometric image (I) of the first housing. Rotor according to claim 1, characterized in that the housings (8 ₁ , 8 ₂ , 10 ₁ , 10 ₂ ) are invariant by a geometric rotation around the axis of rotation and with an angle strictly greater than 360 ° / n . Rotor according to claim 2, characterized in that n is an even number greater than or equal to 4 and the housings (8 ₁ , 8 ₂ , 10 ₁ , 10 ₂ ) are symmetrical in pairs with respect to the axis of rotation (A ). Rotor according to one of the preceding claims, characterized in that the geometric transformation comprises a geometric rotation of a non-zero angle (β) in a plane containing the axis of rotation (A) and the longitudinal direction of the geometric image (I) of the first housing (8 ₁ ). Rotor according to one of the preceding claims, characterized in that the geometric transformation comprises a geometric translation of a non-zero distance (δ) in a plane containing the axis of rotation (A) and the longitudinal direction (D) of l geometric image (I) of the first housing (8 ₁ ). Centrifuge comprising a tank (2), a rotor (3) intended to be placed in the tank (2), and means (4) for rotating the rotor (3), characterized in that the rotor is a rotor according to one of the preceding claims.

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