Patent Grant
8002690
This invention relates to a rotor for a centrifuge, wherein said rotor is rotatably driven about a rotation axis and consists of two parts, i.e. a central bearing part and a waste collecting part which is provided with a waste collecting area, the waste collecting part is separable from the bearing part for waste disposal or cleaning, the bearing part and the waste collecting part are provided with torque transmitting means which interact with each other in a form-fitting and/or adherence manner and are connectable by axially positioning the waste collecting part on the bearing part and disconnectable by axially removing the waste collecting part from the bearing part. The invention moreover relates to a centrifuge.
Centrifuges have been used for decades for a variety of applications and are thus known from practice in many different designs. A rotor with the above specified features is described in the Assignee's older, not prior published German utility model application no. 20 2004 004 215.0. In the rotor described therein, the bearing part comprises one recoil nozzle or a plurality of recoil nozzles for driving the rotor by means of lubricating oil exiting via the nozzle or the nozzles so that the bearing part here forms a drive part of the rotor.
With all centrifuges known and used so far, an inside diameter of the rotor is generally centered on an outside diameter of the axis or an outside diameter of a component located between axis and rotor, such as rotor bearing or drive part. To be able to assemble and disassemble a two-part rotor consisting of a bearing part and a waste collecting part, an assembly clearance between the parts of the rotor is required as a rule; at maximum, slight pressing is permissible so that the rotor can still be assembled and disassembled. To save weight and manufacturing costs, it is increasingly aimed at building the rotor as light-weight as possible, for example by using plastic instead of metal. During operation of the centrifuge, a waste collecting part of plastic is subject in particular to the risk of deformation under the effect of centrifugal forces and/or heat. In the rotors known so far, this results in the inside diameter of the waste collecting part becoming larger. Thus, in centrifuge operation, an increasing clearance results in the area of the connection between waste collecting part and bearing part, resulting in an increasing imbalance and thus performance losses of the centrifuge, a reduced bearing life, and in offending noises.
Accordingly, it is the objective of this invention to provide a rotor and a centrifuge of the type indicated in the beginning which avoid the disadvantages indicated and, in particular, the occurrence of imbalances in operation, thus ensuring high performance with a good endurance limit and a low operating noise level.
In accordance with the invention, this objective is solved by a rotor of the type indicated in the beginning which is characterized in that the circumferences of the bearing part and the waste collecting part are connectable in a form-fitting manner and arranged in such a way that the waste collecting part circumference is placed or rests on the corresponding circumference of the bearing part already at the initial state of the waste collecting part or as a result of the radial expansion thereof produced by a centrifugal force and/or by heating.
In the rotor according to the invention, it is achieved that the bearing part which can be unproblematically designed to be dimensionally stable will ensure exact centering and thus balanced true running of the waste collecting part which is a hollow body and made of plastic and thus is more instable per se. The centrifugal force resulting with the rotation of the rotor during the operation of the centrifuge even ensures that the circumference of the waste collecting part rests on the corresponding circumference of the bearing part which is stable in form and position so that, through the rotation of the rotor, the waste collecting part inevitably assumes an exactly dynamically balanced form and maintains it during the rotation of the rotor. The waste collecting part of plastic can thus be produced relatively easily and with relatively minor material thicknesses without the risk of performance-reducing imbalances which is advantageous not only for the manufacture but also for the operation of the centrifuge. The waste collecting part circumference's resting on the circumference of the bearing part under the effect of the centrifugal force during the operation of the centrifuge moreover advantageously reduces, through the flow of force generated thereby, the micro-movements between the bearing part and the waste collecting part. This counteracts any material removal and wear in this area through the effect of e.g. vibration accelerations introduced from the outside.
A first embodiment furthermore provides that the form-fitting circumference is formed by annular areas. This will particularly effectively ensure an exactly round form of the waste collecting part upon the rotation of the rotor.
It is furthermore proposed that the bearing part is made of metal or plastic and comprises axially on top and/or axially on the bottom one annular area (each) concentric to the rotation axis, that the waste collecting part is made of plastic and comprises axially on top and/or axially on the bottom one annular area, and that—in a combined condition of bearing part and waste collecting part—the annular area of the bearing part encompasses (in each case) the annular area of the waste collecting part radially outside.
Another embodiment provides according to the invention that the annular area of the bearing part is designed, seen in its circumferential direction, extending continuously or as a sequence of two or more annular sections. The annular area fulfills its function of centering the waste collecting part in each of the two above-mentioned embodiments. Depending on the way of manufacturing the bearing part, one or the other embodiment may be more advantageous in terms of manufacturing.
Analogously, the annular area of the waste collecting part, seen in its circumferential direction, can be designed extending continuously or as a sequence of two or more annular sections.
It is provided in one embodiment of the rotor that the/each annular area of the waste collecting part comprises, upon the standstill of the rotor, an initial dimension d of its outer diameter which is smaller than the inner diameter D or equal to the inner diameter D of the annular area of the bearing part, and that upon the rotation of the rotor during operation of the centrifuge the/each annular area of the waste collecting part in its outer diameter is expandable by the effect of the centrifugal force on the diameter D. In this embodiment, it is particularly simple to assemble and disassemble the rotor since, first of all, there is an assembly clearance according to the dimensional difference between the inner diameter D and the initial dimension d of the outer diameter or at least no excess of the outer diameter d relative to the inner diameter D. During the centrifuge operation, the rotation of the rotor and the centrifugal force thus generated will inevitably take care that the outer diameter of the waste collecting part increases from its initial dimension d to the inner diameter D of the annular area of the bearing part whereby it is then ensured that the two annular areas of waste collecting part and bearing part circumferentially rest on each other. Mutual resting provides for a dynamically balanced form of the waste collecting part and for good true running without imbalances. During the standstill of the rotor, the outer diameter of the annular area of the waste collecting part can be reduced again to its initial dimension d, thereby then also enabling easy disassembly of the waste collecting part from the bearing part.
As an alternative to the above described embodiment, it is possible that the/each annular area of the waste collecting part comprises, upon the standstill of the rotor, an initial dimension d of its outer diameter which is larger than the inner diameter D of the annular area of the bearing part, and that after axial positioning of the waste collecting part on the bearing part their annular areas are in connection with each other under pretension. The diameter difference d-D is here, of course, limited to such values in which it is still possible to connect and separate the bearing part and the waste collecting part without any problem.
It is furthermore provided that the bearing part on top has a tubular, upwardly open end section as the annular area and that the waste collecting part on top has a central, axially inwardly extending collar engaging in the end section as the annular area. In this embodiment, the collar projects into the tubular end section; thus, the two interacting annular areas in the upper part of the rotor are very simple, yet effective in design so that the manufacture of the rotor does not entail any major additional manufacturing and machining expenditure for the realization of the annular areas.
To secure the waste collecting part on the bearing part during centrifuge operation and to prevent these two parts from making any undesirable relative movement, it is furthermore provided that the end section forming the annular area and the collar forming the annular area are equipped with interacting latching means forming a disengageable latching connection for the removal of the waste collecting part. The latching connection is preferably manually disengageable to be able to do so without any operating tools during maintenance for the purpose of simple handling and fast removal and installation of the waste collecting part.
In another embodiment of the above mentioned latching connection, the collar forming the annular area preferably comprises two operating arms protruding upwardly over the waste collecting part for manual disengagement of the latching connection. These operating arms enable a simple separation of the waste collecting part from the bearing part without auxiliary tools which is advantageous for fast, time-saving maintenance of the centrifuge.
A modified embodiment provides that the bearing part on top comprises an annular, downwardly open crest as an annular area and that the waste collecting part on top comprises a central, axially outwardly extending collar engaging into the crest as an annular area. In this embodiment, the crest can advantageously be used to simultaneously secure the rotor on the axis against undesirable axial movements.
The form-fitting circumferences provided on the bearing part and on the waste collecting part can be formed, instead of by annular areas, alternatively by axial projections on the one hand and corresponding recesses on the other hand. In this case, the projections and recesses may be provided concentrically or even eccentrically to the rotation axis of the rotor since this is without importance here for the function of the circumference. The axial projections may be allocated to the bearing part or to the waste collecting part; it is also possible to allocate the axial projections partly to the bearing part and partly to the waste collecting part. The corresponding openings are then provided in the correspondingly other part each. Thus, this embodiment has a particular freedom of design with regard to the position of the projections and recesses which may be advantageous for some rotor models.
A shape which is technically simple to manufacture and thus economical will result when the axial projections are formed by pins and the corresponding recesses by borings.
It is furthermore preferably provided that the form-fitting circumference, seen in radial direction, is arranged in the inner half, preferably in the inner third, of the radius of bearing part and waste collecting part. Due to this radially relatively far inwardly provided arrangement of the form-fitting circumferences, they are much less stressed by centrifugal forces during the rotation of the rotor which here permits relatively small material thicknesses and thus saves weight.
Another embodiment of the rotor according to the invention provides that the waste collecting part comprises driving means for driving the rotor.
A further development in this respect proposes that the bearing part comprises a central tubular body with two radially outwardly extending openings and that the waste collecting part comprises two sealing oil channels connected with the openings and each leading to a recoil nozzle. In this embodiment of the rotor, the recoil nozzles are part of the waste collecting part so that new recoil nozzles are also installed in the rotor upon any replacement of the waste collecting part within the scope of maintenance of the centrifuge—which is advantageous for reliable functioning.
It is alternatively proposed that the bearing part comprises driving means for driving the rotor. In this embodiment, the bearing part is thus simultaneously the driving part of the rotor.
A preferred further development in this respect provides that the bearing part comprises one central tubular body forming a lubricating oil channel and two nozzle arms extending radially outwardly from the tubular body with one oil channel each leading to respectively one recoil nozzle, and that the form-fitting circumference of the bearing part is formed or provided at least partly on the nozzle arms. In this embodiment of the rotor, the waste collecting part which is replaced during maintenance of the centrifuge can be manufactured in a particularly simple manner and thus also particularly economically because it does not comprise any driving means. The bearing part here simultaneously forming the drive part can be designed as a high-quality lifetime component and can remain permanently in the centrifuge. At the same time, the form-fitting circumference of the bearing part can here be integrated in a favorable manner in terms of space as well as production engineering.
Another embodiment provides that the form-fitting circumference of the bearing part additionally rests on carrying arms extending radially outwardly from the tubular body. These carrying arms are provided in particular between the nozzle arms to achieve—in the circumferential direction of the bearing part, at uniform spaces and in several places—a fixation of the form-fitting circumference, e.g. the annular area on the bearing part side, and to thus ensure its exact shape and position even over long operating periods of the rotor.
It is furthermore provided that the waste collecting part is designed on the bottom as one piece with a central collar extending axially outwardly as an annular area. This collar provided on the bottom of the waste collecting part can also be simply manufactured so that no appreciable additional manufacturing expenditure is here incurred either. Furthermore, this axially outwardly extending collar in the lower part of the waste collecting part is connectable and disconnectable with an associated annular area of the bearing part by means of a simple axial movement of the waste collecting part relative to the bearing part.
To be able to manufacture the waste collecting part as inexpensively as possible in large quantities, the invention furthermore proposes that the waste collecting part is comprised of two one-piece injection molded parts each which are tightly connected with each other in a plane perpendicular to the rotation axis of the rotor.
It is preferably furthermore provided that the two injection molded parts of the waste collecting part are welded with each other. This welding is particularly favorable if the plastic which the two injection molded parts of the waste collecting part are made of is a thermoplastic. For example, the plastic polyamide (PA) is suitable for it.
Another measure for realizing an inexpensive production is that the tubular body with the nozzle arms and the annular carrying arms is preferably a one-piece die cast part or injection molded part. A light metal in particular, such as aluminum or magnesium, is to be advantageously used as the material. Alternatively, the material to be used for it can also be correspondingly strong and durable plastics, e.g. polyphenylene sulfides (PPS) or thermosetting plastics.
The subject matter of this invention is furthermore a centrifuge which is characterized by comprising a rotor according to any one of the preceding claims. Such a centrifuge is particularly economical, reliable and quiet in operation.
These advantages come to bear particularly well when the centrifuge is a centrifuge for cleaning the lubricating oil of an internal combustion engine, e.g. of a motor vehicle.
Exemplary embodiments of the centrifuge according to the invention are explained in the following with reference to a drawing. In the Figures:
The centrifuge 1 according to
On the axis 5, a rotor 2 is rotatably provided on bearings by the intermediate layer of one upper and lower friction bearing each 51, 52.
The rotor 2 comprises a central bearing part 3 and a disengageable waste collecting part 4 connected with the bearing part 3. With opened cover 14, the waste collecting part 4 can be removed upwardly in axial direction from the bearing part 3 and replaced by a new waste collecting part 4. Full waste collecting parts 4 can thus be regularly and easily replaced.
The bearing part 3 is a lifetime component of the centrifuge 1 and remains permanently on the axis 5. The bearing part is here of metal for stability reasons.
The waste collecting part 4 is here of plastic especially for weight reasons and for realizing low manufacturing costs, as well as for the purpose of simple disposal. Furthermore, the waste collecting part 4 here comprises a top part 41 and a bottom part 42 which are tightly welded to each other along a weld seam 40 running in circumferential direction. In the exemplary embodiment according to
The bearing part 3 is comprised of a tubular body 30 to an axially major part. At its axially upper end, the tubular body 30 of bearing part 3 forms an upper annular area 35, into which an upper annular area 45 of the waste collecting part 4 engages. The annular area 45 of the waste collecting part 4 is here formed by an axially downwardly extending collar whose outer diameter is equivalent to or slightly smaller than the inner diameter of the annular area 35 of the bearing part 3.
By means known per se but not separately shown in the drawing, the rotor 2 is secured on axis 5 against any undue displacement in axial direction towards the top.
At its bottom end area, the bearing part 3 is designed with a bottom annular area 36 into which a second, axially downwardly extending annular area 46 of the waste collecting part 4 engages radially inside. Upon rotation of the rotor 2 in the operation of the centrifuge 1, the upper annular area 45 and the lower annular area 46 of the waste collecting part 4 rest in radial positioning on the upper annular area 35 and the lower annular area 36 of the bearing part 3 as a result of the centrifugal force. Since this bearing part 3 is made of a dimensionally stable metal, an exactly centered alignment of the waste collecting part 4 relative to the bearing part 3 thus results and thus also relative to the rotation axis 20 of the rotor 2 which results in good true running of the rotor even if its waste collecting part 4 consists of a less dimensionally stable material, especially plastic.
A minimum pressure valve 7 known per se is provided with the centrifuge 1 according to
When the lubricating oil pressure is sufficiently high and the minimum pressure valve 7 is opened, the lubricating oil flows through the inlet 18 into a central channel 53 which penetrates the axis 5 in its longitudinal direction. The lubricating oil flow is then divided into two partial lubricating oil flows. A first partial flow flows through at least one first radial channel 54.1 from the area directly above the minimum pressure valve 7 in radial direction towards the outside and further through two radial openings 32 through the bearing part 3 radially from the inside to the outside to finally reach two oil channels 33 which are congruently aligned with the radial openings 32 and lead to the recoil nozzles 34.
A second partial lubricating oil flow flows through the central channel 53 in the axis 5 further to the top and, close to the upper end of the axis 5, it passes into a ring channel 30′ through a second radial channel 54.2. This ring channel 30′ is limited radially inside by the outer circumference of the axis 5 and radially outside by the inner circumference of the tubular body 30 of the bearing part 3. Directly underneath the upper friction bearing 52, at least one oil inlet 44 which extends in radial direction and is here designed as a boring will pass from the annular gap 30′ into the interior of the waste collecting part 4. The lubricating oil to be cleaned then flows through the waste collecting part 4 from top to bottom seen in axial direction; in the bottom part 42 of the waste collecting part 4, an oil drain 47 is provided radially inside which is not completely visible here through which the cleaned lubricating oil passes into a pressureless oil drain area 13 of the housing 10.
As known per se, the upper friction bearing 52 is supplied with lubricating oil through at least one channel which is not separately shown here.
To prevent any reciprocal interference between the oil jets exiting from the recoil nozzles 34 and the partial oil flow exiting from the outlet 47, either deflecting ribs 17 are provided on the top side of the housing part 10′ as shown in the right half of
The lower part of
The lower annular area 36 of the bearing part 3 is held on the two nozzle arms 31 as well as the two carrying arms 36 provided between the nozzle arms 31. The annular area 36 here has the shape of a circular ring disk with a circumferential inner circumference surface radially extending inwardly.
The upper part of
In assembled condition, the annular area 46—which is here formed of a total of four sections 46′ following each other at a small distance—rests on the inner circumference surface of the annular area 36 of the bearing part 6 and is precisely centered in its position by it. This centering is even improved upon rotation of the rotor 2 during operation of the centrifuge 1 because the resulting centrifugal forces ensure an exact placement of the outer circumference surface of the annular area 46 of the waste collecting part 4 on the inner circumference surface of the annular area 36 of the bearing part 3.
Finally,
In an enlarged detail,
A small part of the bottom part 32 of the waste collecting part 4 is visible radially outside of the tubular body 30. On the bottom right in
Here again, the bearing part 3 has a central tubular body 30 whose upper end is designed as the upper annular area 35 and the lower annular area 36 is provided at its lower end area.
Here again, the waste collecting part 4 is comprised of two parts, i.e. the pot-shaped top part 41 and the bottom part 42 which are connected with each other along the weld seam 40. As the upper annular area 45 of the waste collecting part 4, an axially inwardly projecting collar is integrally molded in the center of the top part 41, the collar engaging radially inside in the upper annular area 35 of the bearing part 3. In this area, a rolling bearing is furthermore provided as the upper bearing 52 on the inside of the tubular body 30 in this embodiment of the rotor 2. The oil inlet 44 is provided directly underneath the bearing 52 and is used for the introduction of the lubricating oil to be cleaned into the interior of the waste collecting part 4.
An axially downwardly projecting collar is integrally molded in one-piece on the bottom part 42 of the waste collecting part 4 as the lower annular area 46. In assembled condition as shown in
In an enlarged view,
Radially outside of the bearing part 3, the lower part of the waste collecting part 4 is located which is provided radially inside with the axially downwardly projecting lower annular area 46 as a one-piece collar integrally molded to the bottom part 42. Here again, it is clearly shown that, in the assembled condition of the rotor 2, the outer circumference of the lower annular area 46 of the waste collecting part 4 rests on the inner circumference of the dimensionally stable lower annular area 36 of the bearing part 3 by means of which the waste collecting part 4 is centered relative to the bearing part 3 and relative to the rotation axis 20.
The annular area 36 here has an inner diameter D which is adapted to the outer diameter d of the annular area 46. In its basic condition, upon standstill of the rotor 2, the outer diameter d of the annular area 46 can also have a dimension which is smaller by an assembly clearance than the inner diameter D; the centrifugal force upon rotation of the rotor 2 then provides for an expansion of the outer diameter d to the inner diameter D.
In an enlarged view,
The upper annular area 45 of the top part 41 of the waste collecting part 4 interacts with the annular area 35, and here again, the outer circumference of the annular area 45 rests on the inner circumference of the annular area 35. In terms of its accuracy, the resting effect is even positively influenced upon rotation of the rotor 2 (cf.
The upper bearing 52 is provided in the form of a rolling bearing underneath the two annular areas 35 and 45. Inlet 44 is located under the rolling bearing 52, and the lubricating oil to be cleaned passes through it into the interior of the waste collecting part 4. Radially extending deflecting walls 48 regularly spaced from each other in circumferential direction are provided in the interior of the waste collecting part 4, the walls ending radially inside spaced apart from the tubular body 30 of the bearing part 3.
Finally, latching means 39, 49 are also visible at the very top in the center of
Finally,
In the upper right-hand area of
The upper end of the tubular body 30 is designed with the upper annular area 35 into which engages the upper annular area 45 of the waste collecting part 4. The latching means already mentioned before are here concretely formed by a latching groove 39 integrally molded in the inner circumference of the annular area 35 and by a latching bead 49 matching the latching groove 39 on the outer circumference of the annular area 45 of the waste collecting part 4.
The two operating arms 49′ project upwardly through the top part 41 of the waste collecting part 4. When they are pressed by an operating person in radial direction inwardly onto each other, the latching bead 49 extends from the associated latching groove 39, and the waste collecting part 4 can be smoothly removed in axial direction upwardly from the bearing part 3 to replace a spent waste collecting part 4 filled with waste particles by a fresh waste collecting part 4 within the scope of maintenance of the centrifuge.
Furthermore, with the bearing part 3 shown in
Here again, the centrifuge 1 comprises a housing 10 which is closed on the upper side with a screw cover 14. In this respect, the screw cover 14 has an external thread 16 which fits into an internal thread of the housing 10 here not shown.
The rotor 2 is rotatable on bearings on the axis 5 in the interior of the housing 10, here essentially within the cover 14. With a bottom threaded end 50, the axis 5 is screwed into an axis reception 12 which is centrally provided in a housing part 10′. With its upper end 50′, the axis 5 engages centrically into a matching cavity on the inside of the cover 14.
By means of two bearings 51 and 52, the bearing and drive part 3 is provided on the axis 5 and here comprises a tubular body 30 from whose bottom end two nozzle arms 31 extend diametrically opposed to each other radially outwardly. One oil channel 33 runs through each nozzle arm 31, the channel ending at the radially exterior end of each nozzle arm 31 in one recoil nozzle 34 each.
In this exemplary embodiment as well, the waste collecting part 4 is combined of two parts, of a top part 41 and of a bottom part 42 which are tightly connected with each other along a weld seam 40. As indicated in the left half of
In its central upper area, the top part 41 has an axially upwardly extending collar which forms an annular area 45. This annular area 45 of the waste collecting part 4 is enclosed radially outside by an annular area 35 of the bearing and drive part 3. The annular area 35 is here designed as a separate crest in annular form which is provided on the upper end of the axis 50′ with the intermediate layer of an upper rolling bearing 52. The annular area 45 of the inherently less stable, plastic waste collecting part 4 is centered by the dimensionally stable annular area 35, and this centering will even be improved during a rotation of the rotor 2 due to the resulting centrifugal forces acting upon the annular area 45.
During operation of the centrifuge 1 according to
A second partial lubricating oil flow flows upwardly through the ring channel 30′ and reaches the interior of the waste collecting part 4 close to its upper end—via a throttle point 37 and through at least one inlet 44. This second partial lubricating oil flow essentially flows through the waste collecting part 4 from top to bottom and then exits from the waste collecting part 4 through an outlet 47 located on the bottom and radially inside. The waste particles supplied to the lubricating oil collect in the waste collecting part 4 radially outside due to the resulting centrifugal forces and are thus separated from the lubricating oil.
The lubricating oil exiting from the waste collecting part 4 through the outlet 47 and the lubricating oil exiting from the nozzles 34 combine below the rotor 2 in a pressureless area 13 of the centrifuge 1 and drain off from there, for example into the oil sump of an associated internal combustion engine.
When the cover 14 is unscrewed, the upper end of the axis 50 can be removed upwardly in axial direction together with the rolling bearing 52 provided on the top and the crest seated outside on the bearing 52 and forming the annular area 35. Simultaneously therewith or thereafter, the waste collecting part 4 can also be separated by the upwardly axial removal from the bearing and drive part 3, and it can be replaced by a fresh waste collecting part 4. The centrifuge 1 is ready to operate again after positioning the upper end of the axis 50′ with the bearing 52 and the annular area 35 and after screwing on the cover 14.
The lower part of
Supplementary to the embodiment according to
At the same time, the annular areas 35 and 45 here also serve to center the waste collecting part 4 upon rotation of the rotor during the operation of the centrifuge.
In the above described exemplary embodiments of the rotor 2, the form-fitting interacting circumference is used for centering the waste collecting part 4 and is formed by annular areas on the bearing part 3 and the waste collecting part 4. In the following described examples, the form-fitting circumference on bearing part 3 and waste collecting part 4 is formed by axial projections on the one hand and correspondingly arranged openings on the other hand, with different embodiments and arrangements being possible.
With the example shown in
In a view diagonally from below,
In the same manner of presentation as in
With the embodiments according to the
With the bearing part 3 visible in
In all exemplary embodiments according to the
As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2006/003962 | 4/28/2006 | WO | 00 | 11/2/2007 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2006/117141 | 11/9/2006 | WO | A |
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| 20090272680 A1 | Nov 2009 | US |
