Fluid handling – Systems – Multiple inlet with single outlet
Reexamination Certificate
2001-10-29
2004-06-22
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Systems
Multiple inlet with single outlet
C251S061200
Reexamination Certificate
active
06752172
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus for the supply and/or branching of a secondary flow into and/or out of a main flow of a medical fluid comprising a fluid guidance body in which at least one main passage open to one side and at least one secondary passage opening into the main passage are provided and comprising a covering film which is disposed above the open side of the main passage on the fluid guidance body, with the opening of the secondary passage into the main passage being closable by the covering film. The invention further relates to a valve actuator for such an apparatus having a main plunger surface to press on the covering film at the edges of the main passage and a secondary plunger surface to press the covering film onto the opening of the secondary passage.
BACKGROUND OF THE INVENTION
So-called disposable cassettes of the membrane type are known, for example from WO 97/09074, in which medical fluids such as dialysis fluid flows into passages open to one side. The passage walls and the surfaces disposed between the passages are formed by a cassette body made as a rule in injection moulding. The passages open to one side are sealed by a covering film which is placed on, for example by being welded on along the passage edges or by pressing on, optionally onto passage edges made in an elevated manner.
A machine into which such a disposable cassette is inserted as a rule includes the actuating system for measuring functions, pump functions and valve functions and areally clamps the cassette together with the covering film disposed thereon. The edge layer of the surface on the machine side which lies on the covering film consists as a rule of an elastomer.
In particular with disposable cassettes which are part of an extra-corporeal blood circulation for extra-corporeal blood treatment, the requirement exists in a technical process respect that alternatively fluids such as infusion solutions, medicines, heparin, substituate and the like should be dosed in or fluid samples taken out of the passages. Valve positions are required for this purpose in order to connect the main passage, through which the medical fluid flows, to a corresponding secondary passage. This secondary passage is regularly closed since the dosing in or sampling only take a short time.
Such devices are subject to a variety of demands which have not yet been satisfactorily solved by the prior art. Generally, the functions to be met should be achieved with a compact arrangement. When the secondary passage is transposed into the main passage, however, problems result with respect to a low turbulence and low resistance flow of the medical fluid in the main passage, in particular when this is blood. Furthermore, the covering film in known arrangements tends to fatigue as a result of the secondary passage being kept closed over a long time.
SUMMARY OF THE INVENTION
It is therefore the underlying object of the present invention to provide an improved apparatus of the kind first given and an improved valve actuator of the kind first given, to avoid the disadvantages of the prior art and to further develop these in an advantageous manner. The dosing in and the sampling should preferably be made possible in a securely closing and low wear manner with a simple, compact and low cost arrangement without lasting interference to the flow relationships of the medical fluid.
This object is solved in accordance with the invention by an apparatus for supplying and/or branching off of a secondary flow into and/or out of a main flow of a medical fluid, which includes a fluid guide body, in which at least one main passage open to the side and at least one secondary passage opening into the main passage are provided. A covering film is disposed on the fluid guide body above the open side of the main passage, and the orifice of the secondary passage into the main passage can be closed by the covering film. The secondary passage is formed such that the main passage is substantially free of wake space in the region of the orifice of the secondary passage. The said object is solved in accordance with the invention by a valve actuator for the apparatus which includes a main plunger surface to press the covering film onto the rims of the main passage and a secondary plunger surface to press the covering film onto the orifice of the secondary passage, and wherein the main plunger surface and the secondary plunger surface are in the same plane.
The secondary passage, its orifice and the main passage are therefore designed in a flow-favourable manner such that a main passage flow which is free of wake space arises in the region of the orifice of the secondary passage and does not characteristically differ from the flow in the valve-free sections of the main passage. These flow qualities substantially improve the haemocompatibility of the apparatus.
In order to also achieve a low vortex and low resistance flow of the medical liquid in the main passage in the region of the secondary passage feed, the outside of the wall of the secondary passage section located in the main passage advantageously has a rounded shape favourable for flow and free of corners or edges which cause wake spaces and vortexes. The outside of the secondary passage section located in the main passage can in particular have a streamlined form in accordance with the flow direction of the main flow in the main passage. “Streamlined form” is here understood to mean a shape with a favourable circulation with which separations and vortexes or turbulences are effectively reduced and, in the ideal case, fully prevented. Unlike an only circular cross-sectional shape, vortexes and bubbles are effectively prevented by the streamlined shape and a laminar circulation of the secondary passage disposed in the main passage achieved. The flow resistance can be kept small despite the fact that the secondary passage extends in the main passage. The outer contour of the secondary passage is in particular of streamlined shape such that an eddy-free and laminar circulation is ensured which does not characteristically differ from the flow in the valve-free main passage sections. These flow qualities contribute in particular to the haemocompatibility of the apparatus for the event that blood flows through the main passage.
The ratio of the section length to the section width of the streamlined shape can generally be selected differently and matched to the circumstances of the main passage flow. In accordance with a preferred embodiment, the extent of the outside contour of the secondary passage located in the main passage in the main flow direction is at least twice as large as the extent of the outside contour transverse to the main flow direction.
In a further development of the invention, the outside contour of the secondary passage has an acutely tapering separation edge at the leading side and the trailing side, at least at the trailing side. The outside contours of the secondary passage can have a curvature continuously. The separation edge itself can also be rounded. The leading edge can be designed much rounder than the trailing edge, as is known from hydrofoil sections or drop sections. A laminar circulation is maintained in this way and connected to the advantage that the rounded leading edge offers fewer possibilities for stringy or sticky fluid components of the main flow to stick at the leading edge. A symmetrical design of the leading edge and the trailing edge can be advantageous if the flow in the main passage should run through this in changing directions.
In accordance with a preferred embodiment of the invention, the fluid guide body is characterised in that the orifice of the secondary passage into the main passage is substantially disposed in the plane set by the adjacent rims of the main passage. The end of the secondary passage at the orifice side is vertically coincident with the passage rims in the main passage and is thus in the plane of the covering film when this is stretched from the passage rims over the main passage. The
Fresenius Medical Care Deutschland GmbH
Hepperle Stephen M.
Jacobson & Holman PLLC
LandOfFree
Disposable cassette having a sealing membrane and a valve... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Disposable cassette having a sealing membrane and a valve..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Disposable cassette having a sealing membrane and a valve... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3344807