Pumps – Expansible chamber type – Elongated flexible chamber wall progressively deformed
Reissue Patent
1994-09-28
2001-02-27
Freay, Charles G. (Department: 3746)
Pumps
Expansible chamber type
Elongated flexible chamber wall progressively deformed
C417S478000, C417S479000, C251S009000
Reissue Patent
active
RE037074
ABSTRACT:
This invention relates to pumping devices.
The invention seeks to provide improved such devices and in particular improved such devices for use in medical application such as the intravenous supply of fluids to a patient.
According to this invention, a pumping device comprises means for accommodating a length of tubing providing, in operation, passage for liquid through said device, means for deforming said tubing whereby to reduce its volume and, on either side of said deforming means, controllable valve means for restricting the flow of liquid through said tube.
According to a feature of the invention, a pumping device comprises means for accommodating a length of tubing providing, in operation, passage for liquid through said device, means for deforming said tubing whereby locally to reduce its volume, controllable valve means on either side of said deforming means for restricting the flow of liquid through said tubing and control means arranged to control the operation of said deforming means and said valve means whereby at times when said tubing is being deformed by said deforming means the valve means on the input side is in a condition of restricted flow whilst the valve means on the output side is in a condition of increased flow and at times when said volume is being restored the valve means on the output side is in a condition of restricted flow whilst the valve means on the input side is in a condition of increased flow, wherein liquid is displaced from the tubing as a function of the volume of the tubing reduced by the deforming means.
Normally the valve means on the input and the output sides are such that when fully operated, flow is stopped or permitted, as the case may be.
Normally the arrangement is such that deformation of said tubing by said deforming means is non-occlusive, that is to say that at the extreme of deformation the opposite internal surfaces of the tubing which approach each other do not make contact.
Preferably said deforming means is such that said tubing is first deformed in one direction and then in another which tends to restore the original cross-sectional shape of said tubing. In some examples of devices in accordance with the invention the deforming means is such that deformation in said other direction ceases as the original cross-sectional shape of the tubing is regained. In other examples the squeezing means is such that squeezing in said other direction continues beyond restoration of the original cross-sectional shape of said tubing to cause further local deformation of the cross-sectional shape of said tubing.
Preferably said deforming means comprises two members each having a series of transverse blades or ridges shaped to provide a valley through which said tubing may pass, one of said members being inverted relative to the other with its ridges interdigitated with the ridges of the other, said two members being arranged to move relative to one another in a direction transverse to the direction of passage of said tubing through said two valleys whereby to deform said tubing.
Preferably each ridge has a recess which is generally semi-circular to one side and of progressively decreasing depth to the other side until the full height of the ridge is reached.
Preferably all of the ridges of one member are substantially identical, with the generally semi-circular portions of their apertures to the same side.
Preferably again, viewed in the direction of passage of the tubing through the valley formed by the ridges, all of the ridges of one member appear superimposed.
With an arrangement as just described the generally semi-circular portions of the apertures in the ridges of one member are to one side and the generally semi-circular portions of the apertures in the ridges of the relatively inverted member are to the other side, as viewed in the direction of passage of said tubing through the valley.
Where, as will normally be the case, the length of tubing, when undeformed, is of substantially constant circular section through the pumping device, the curvature of the generally semi-circular portions of the apertures in the ridges of both members are normally such that in one position of relative movement of the two members, the generally semi-circular portions of the apertures in the ridges of the two members together form a passage of substantially circular cross-section of diameter closely similar to that of said tube.
Preferably said formed passage is of diameter slightly less than that of said tubing whereby gently to nip said tubing.
Preferably the ridges of each member bear on the surfaces between the ridges of the other member.
Preferably said two members are biassed one towards the other by resilient means, e.g. a spring.
In a preferred embodiment one of said two members is arranged to be stationary during operation whilst the other moves in the manner of a shuttle.
Where the pumping device comprises a housing with a closure, such as a door or lid, preferably the member which is arranged to be stationary during operation is carried by said closure whereby opening said closure releases said tubing from said deforming means. With such an arrangement, preferably the member which is arranged to be stationary during operation has limited freedom to move, independent of said closure, towards and away from said other member, biassing means, such as a spring, being provided between it and said closure tending to urge it towards said other member.
Preferably said member which is arranged to move in the manner of a shuttle is arranged to be driven via an eccentric by an electric motor which is controlled to move in operation in a series of discrete steps producing incremental steps of said member in a direction producing deformation of said tubing.
Preferably said last-mentioned member is arranged to be returned by said motor in the opposite direction in one relatively rapid movement.
Preferably each valve means comprises a guide member having a channel therethrough for said tubing and, within said channel, a rotary member having an off-centre projection extending generally parallel to the axis of rotation of said rotary member and having one face against which said tubing lies, the arrangement being such that said face defines, in part, said channel and partial rotation of said rotary member causes said tubing to be occluded by the resultant action of said face upon said tubing.
Preferably said face of said projection is partially recessed with a profiled surface adapted to bear on said tubing when said rotary member is partially rotated to a “start” position whilst the resulting overhang provides a closure (which may be partial) over the channel in said guide member capturing said tubing therein. Preferably stop means are provided for each rotary member whereby movement is limited in one direction of rotation to a position in which the face of its projection is so aligned with the tubing as to permit said tubing to be removed from said channel and in the other direction of rotation to a position beyond that at which said tubing is occluded. Preferably the control of said rotary members is such that in normal operation said last-mentioned position beyond that at which said tubing is occluded is not reached.
Preferably the stops in each case are provided by an arcuate slot or recess in the rotary member and co-axial with its axis of rotation, in co-operation with a fixed pin or other abutment.
Normally the two valve means are controlled to be operated without, or substantially without, overlap between the periods at which each is permitting liquid flow. In other words, movement of the rotary member of one valve means in a direction to reduce flow is arranged to be completed, or substantially completed, before movement of the rotary member of the other valve means in a direction to increase flow, and vice versa.
With an arrangement as just described, normally operator controllable means are provided for causing the rotary members of both valve means to rotate to a position in which the faces of said projections are so aligned with the tubi
Danby Hal C.
Faulkner Eric A.
Baxter Intl. Inc.
Freay Charles G.
Konalik Francis C.
Schaatsma Paul E.
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