Liquid purification or separation – Casing divided by membrane into sections having inlet – Each section having inlet
Reexamination Certificate
2000-05-16
2002-07-30
Kim, John (Department: 1723)
Liquid purification or separation
Casing divided by membrane into sections having inlet
Each section having inlet
C210S321800, C210S321880, C210S321890, C210S450000, C210S455000, C210S500230
Reexamination Certificate
active
06426002
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a filter device having two flow spaces, of which a first space, preferably a permeate space, is formed by the tubular or capillary tube passages of a hollow-fiber bundle poured at its ends into a molding compound, and a second space, preferably a filtrate space, is formed by a housing enclosing the fiber bundle, the first space being sealed off by caps, placed on the molding compounds, with sealing devices running over the peripheral areas of said molding compounds, and the molding compounds being braced against the housing.
BACKGROUND OF THE INVENTION
The German laid open print 26 46 358 discloses a filter device in which the hollow-fiber bundle encloses a central conduit in a ring-like manner, and the ends of the ring-shaped hollow-fiber bundle are sealed off by a molding compound both with respect to the central conduit and with respect to the housing casing concentrically enclosing it.
Another known filter device likewise comprises a tubular housing which encloses the hollow-fiber bundle, the ends of the hollow-fiber bundle being joined to the ends of the tubular housing by a molding compound. In this filter device, the housing is provided in each case with radial connection pieces, adjacent to the molding compounds, which form the inlets and outlets to the second flow space. The capillary tubes of the hollow-fiber bundle enclosed by the molding compounds are cut at their end faces to open them. Caps provided with connection pieces which form the inlets and outlets of the first flow space are then placed sealingly on the ends of the tubular casing.
These known filter devices are used, for example, as capillary dialyzers, the flow spaces formed by the capillary-tube passages forming the blood chamber, and the housing enclosing the hollow-fiber bundle forming the dialysate chamber in which the dialysate flows around the hollow fibers.
The problem existing in the known filter devices is that the molding compound, usually made of PU [polyurethane fiber], which hardens in a disk shape and forms a sealing between the two flow spaces, shrinks when hardening, so that stresses develop in the disk-shaped sealings formed by the molding compounds which can lead to cracks and even detachments of the molding compounds from the housing casing enclosing them. As a result, the two flow spaces are no longer completely sealed off from one another, and the adhesion of the sealing compounds to the housing enclosing the fiber bundle, said adhesion producing the seal, is no longer reliably assured.
In a filter device of the type indicated at the outset disclosed by EP 0 305 687 B1, the disk-shaped molding compounds are enclosed by interposed rings to which the molding compounds do not adhere, so that they can shrink free of stress. This stress-free shrinking prevents cracks in the disk-shaped molding compounds, and makes it possible to dispense with a direct sealing between the peripheral edge of the sealing compounds and the housing enclosing them. To nevertheless maintain a sealing between the two flow spaces, the first space is sealed off by caps placed on the molding compound, and specifically by sealing devices which run over the edge area of the molding compound and against which the caps are pressed.
In this known filter device, the problem now exists of producing a connection to the second space formed by the housing enclosing the fiber bundle. This connection is produced in the known filter device, in that the diameter of the tubular housing is widened at its end areas more or less in the manner of a sleeve, these widened areas being provided with radial connection pieces. These connection pieces open through into the second space formed by the housing, the widened sections of the housing being sealed off from the first space because the caps are sealingly joined to the widened sections, so that a sealing is produced to the outside by the cap edge, and a sealing is produced with respect to the first space by the circumferential sealing ring. This type of arrangement of the connection pieces at the second space formed by the housing is relatively costly. Furthermore, dead spaces which are poorly rinsed develop above or below the connection pieces, at which gas bubbles can collect. This can have a disadvantageous effect during disinfecting or sterilization, as well as generally when handling.
OBJECTS AND SUMMARY OF THE INVENTION
Therefore, the object of the invention is to produce a filter device of the type specified at the outset in which, on one hand, it is reliably assured that the two flow spaces are sealed off from one another by the hardened molding compounds, and on the other hand, a simple arrangement of the connection pieces for the second flow space is produced and poorly rinsed dead spaces are moreover avoided.
This objective is achieved according to the invention, given a filter device having two flow spaces, the first space formed by tubular or capillary tube passages of a hollow-fiber bundle, said fiber bundle being poured at its ends into a molding compound, and a second space formed by the housing surrounding the fiber bundle. The invention further entails the first space being sealed off by caps, placed on the molding compounds, with sealing devices being placed over the peripheral areas of the molding compounds, and the molding compounds being braced against the housing. The molding compounds are hardened in molds enclosing them at their end faces and peripheral sides to form disks. Caps are provided for the ends of the first space that seal to the molding compound and have a connection piece providing inflow/outflow access to the first space. A second set of caps, overlapping the first caps, is provided, said caps having a connection piece providing inflow/outflow access to the second space. The edges of the second caps being joined to the housing in a fluid tight manner, so that between the first and second set of caps, interspaces are formed, said interspaces being connected to the second space. In the filter device according to the invention, the molding compounds are hardened in molds enclosing them on the face and at their sides, so that the molding compounds are able to shrink free of stress. As in the known filter device, the sealing between the disk-shaped molding compounds thus formed and the first caps is effected by inserted sealing means. However, to produce a simple access to the second flow space, the corresponding connection pieces are no longer arranged on the housing itself, but on the second cap overlapping the first cap. This simplifies the filter device.
The inner edges of the second caps overlapping the molding compounds advantageously extend beyond the molding compounds to the inside, so that a flow space is produced between the circumferential wall of the second caps and the molding compounds or the fiber bundles enclosed by them.
According to a preferred specific embodiment, the pipe-section-shaped housing, into which the hollow-fiber bundle is drawn, is provided at the ends of its casing with tooth-like or scalloped projections formed by axial notches or indentations running out freely, the outer areas of the projections being integrated into the molding compounds, so that the free inner areas of the notches or indentations form flow passages for the fluid. Since the housing, which is pipe-section-shaped or preferably provided with a circular cross-section, is made of a material having elastic properties such as PC (polycarbonate), wreath-shaped edges made of flexible tongues are formed by the notches or indentations, said edges being at least partially enclosed by the molding compound. When the molding compound then hardens to form the disks, they can s rink essentially free of stress, because the flexible tongues offer no significant resistance to this shrinking. According to this refinement of the present invention, the disks formed by the molding compounds are firmly joined to the ends of the tubular housing, so that the two flow chambers can then be reliably separated from one anot
Hahmann Uwe
Heilmann Klaus
Schönhofen Michael
Wiesen Gerhard
Fresenius Medical Care Deutschland GmbH
Kenyon & Kenyon
Kim John
LandOfFree
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