Imperforate bowl: centrifugal separators – Including vibration damping means
Reexamination Certificate
1998-06-10
2001-05-01
Cooley, Charles E. (Department: 1723)
Imperforate bowl: centrifugal separators
Including vibration damping means
C384S535000
Reexamination Certificate
active
06224533
ABSTRACT:
THE BACKGROUND OF THE INVENTION AND PRIOR ART
The present invention refers to a support device for a centrifugal separator having a centrifuge rotor, which is provided in a frame member to be rotatable about an axis of rotation by means of a bearing member, said support device comprising a support element provided between the bearing member and the frame member and arranged to absorb relative movements between the centrifuge rotor and the frame member, said support element comprising an inner mounting portion, which is arranged to be essentially immovable in relation to the bearing member, and an outer mounting portion, which is arranged to be essentially immovable in relation to the frame member.
The present invention will be described in connection with a so called upper bearing support of a centrifugal separator. However, it is to be noted that the invention is applicable also to other bearing supports of centrifugal separators. Such conventional bearing supports are essentially of two types, namely bearing supports in which springs apply a force to friction buffers and bearing supports in which a dampening rubber element is included.
These known bearing supports comprise many details making them complicated and expensive. The dampening properties of the friction buffers and of the rubber elements are difficult to calculate. On the friction surfaces being dampened through friction, coatings (coke) are formed, which change the dampening properties and result in a great risk of jamming. The dampening properties of the rubber material are difficult to predict and change over the time. In the friction buffers, wear particles are formed, which reduce the working life of the bearing support. The heat transfer is poor in these known bearing supports, since rubber has a low heat conducting capability and the friction surfaces of the friction buffers deteriorates the heat transfer.
WO 89/10794 discloses an example of such a known bearing support for a centrifugal separator having a centrifuge rotor which is rotatable in a frame member by means of a bearing member. The bearing support comprises a number of support elements which extend radially outwardly from the bearing member and which each encloses a spring member of a helical spring type. These support elements are arranged to permit relative radial movements between the centrifuge rotor and the frame member by being moveable in a hole of the frame member. The friction, which exists between the contact surfaces of the support element and adjacent elements, results in a dampening of the radial movement and a heat development, which is of course not desirable. U.S. Pat. No. 2,487,343 discloses such a similar bearing support which in addition comprises a number of spring members extending axially and thus being arranged to permit axial relative movements between the centrifuge rotor and the frame member. DE-C-558 937 and GB-C-9002 disclose further examples of known bearing supports having helical springs extending in a radial direction. These known bearing supports have a highly complicated construction with a great number of components included, which of course makes the manufacture and the mounting of the bearing supports labor intensive and expensive, and in addition makes it difficult to transfer heat away from the bearing member.
GB-A-1 397 172 discloses a support device of the type initially defined for a centrifugal separator with a centrifuge rotor which is provided in a frame member to be rotatable about a rotational axis by means of a bearing member. The support element of this known support device comprises a first group of at least three elastic components which are arranged to oscillate merely in radial direction with respect to the rotational axis, a second group of at least three elastic components which are arranged to oscillate merely in an axial direction, and a rigid member connecting the elastic components of the first and second groups. Certainly, the known support element may be manufactured as an integrated unit but it has a highly complicated shape since it requires different components for different functions. Furthermore, the axial extension of the known support element is relatively long.
SE-C-54 165 discloses another type of support element for a centrifugal separator, which is provided between a frame member and a bearing bushing for a rotating shaft. The support element is designed as a plane or corrugated membrane and arranged to permit an oscillating movement of the bearing bushing and the shaft, at the same time as a radial relative movement between the frame member and the bearing bushing is excluded.
SUMMARY OF THE INVENTION
The object of the present invention is to provided a constructively simple support device arranged to permit axial, radial and oscillating movements of a centrifuge rotor in a centrifugal separator. Furthermore, it is aimed at an effective heat transfer of the support device.
This object is obtained by the support device initially defined and characterized in that
the support element comprises at least three flexible connecting portions which each extends between the inner mounting portion and the outer mounting portion,
each connecting portion is arranged to permit radial and axial movements between the centrifuge rotor and the frame member, and
the inner mounting portion, the connecting portions and the outer mounting portion of the support element form an integrated unit manufactured in one single piece of material.
Due to the features that each connecting portion permits axial as well as radial relative movements between the inner and outer mounting portions of the support element, i.e. between the frame member and the centrifuge rotor, and that each connecting portion proper comprises both these functions, a significantly simplified design of the support device is obtained in comparison with previously known techniques, such as the one disclosed in for instance GB-A-1 397 172 mentioned above. Furthermore, such an integrated unit enables a simple structure of the support device from a constructive and a manufacturing point of view. In addition, the support element may be arranged to permit relative oscillating movements between the centrifuge rotor and the frame member. In such a manner, a fully flexible support device is obtained for a centrifuge rotor which thus is permitted to oscillate or pivot, and to move axially and radially in its support in the frame member of the centrifugal separator.
According to a further embodiment of the invention, said integrated unit is cut from said single piece of material. Such a cutting may be performed by any suitable known working method, for instance plasma cutting, water cutting or laser cutting. In relation to other cutting methods, such working methods result in a high surface finish, which is important in order to avoid fractures in the material. A piece of material may comprise a metal sheet material, which may be essentially planar or curved in such a manner that it forms for instance a S- or C-like shape, seen in an axial section through the support element. By such a support element of metal, which extends in one piece between the bearing member and the frame member, an effective heat conducting capability may be obtained for removing the heat formed in the bearing member.
According to a further embodiment of the invention, each of the inner and outer mounting portions has an annular shape, each connecting portion extending from the inner mounting portion to the outer mounting portion along a non-linear path. By such a non-linear extension elastic, resilient properties of the connecting portions are obtained. Such an elastic connecting element permits the bearing to follow the oscillating or pivoting movements of the centrifuge rotor against a centering spring force, which may be calculated in an easy manner. By varying the non-linear extension one may obtain desired resilient and dampening properties in different directions.
According to a further embodiment of the invention, each connecting portion has such a length that t
Bengtsson Leif
Grandin Staffan
Hjelm Jonas
Klintenstedt Kjell
Larsen Torbjörn
Alfa Laval AB
Cooley Charles E.
Fish & Richardson P.C.
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