Pumps – Expansible chamber type – Elongated flexible chamber wall progressively deformed
Patent
1996-10-29
1998-04-21
Thorpe, Timothy
Pumps
Expansible chamber type
Elongated flexible chamber wall progressively deformed
4174772, 604153, F04B 4309
Patent
active
057411255
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a peristaltic pump system.
2. Description of Related Art
Peristaltic pumps are used, particularly but not exclusively, in the medical field to deliver medication in liquid form, e.g. for perfusions at a very regular flow rate.
In conventional manner, e.g. as described in French patent applications Nos. 2 383 333 or 2 644 212, these pumps comprise a motor assembly and a cassette. The cassette is essentially constituted by a tube in which the liquid to be pumped flows, said tube being deformable and pressed against a wall. Within a loop formed by the tube, there are to be found a plurality of wheels that are driven so that they revolve together, the wheels squeezing the tube locally. The wheels are driven by rotating the shaft of the motor assembly when the cassette is mounted thereon. Between points where it is squeezed, the tube defines liquid-filled chambers, and rotation of the wheels causes the chambers to move away from the tube inlet and towards the tube outlet. This causes liquid to be transferred from the tube inlet to its outlet at a flow rate that is very accurate and depends firstly on the volume of the tube between two squeeze points, and also, of course, on the speed with which the wheel assembly revolves.
It will be understood that between two medication-dispensing operations, the motor portion of the pump can be retained while the tube must naturally be changed, and in fact it is the entire cassette that needs to be changed. Unfortunately, the cassette contains not only the tube but also the drive wheels, and they need to be machined very accurately in order to achieve high pumping accuracy in practice. In other words, although the cost of the cassette is small compared with that of the motor assembly, it is nevertheless not negligible.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a peristaltic pump system in which the "cassette" that needs to be discarded after each use is simpler in structure and is therefore cheaper.
To achieve this object, the peristaltic pump system of the invention is characterized in that it comprises:
a first assembly comprising: projects; face that is symmetrical about said axis; and having an orifice suitable for allowing the free end of said shaft to pass therethrough; and said plate, said movable means comprising means for substantially preventing said wheels from moving in translation relative to said plate along their pivot axes, for holding the pivot axes of said wheels parallel to said axis of the shaft, for allowing each wheel to rotate, and for guiding the axes of said wheels in translation along radial directions; and
a second assembly, independent of the first and comprising: assembly, the tread walls of said wheels come into contact with said tubular duct towards the axis of rotation of the mounting means in such a manner that a portion of each wheel is disposed facing said orifice; and assembly, the free end of said shaft penetrates through said orifice so that the side wall of the shaft comes into contact with the tread walls of said wheels to spread said wheels apart in radial directions away from the axis of the shaft, thereby causing said tubular duct to be locally squeezed between said wheels and said wall of said second assembly.
It will be understood that the so-called "second" assembly constitutes the equivalent of a portion of a prior art cassette, and is referred to herein as an "insert". Its structure is very simple since it comprises no more than a wall portion, preferably provided with a cover, and associated with the portion of deformable hose that co-operates with the wheels. This structure is thus very simple and cheap. It will be understood that the set of wheels forms an integral portion of the first assembly, i.e. the motor unit, and this is naturally not changed between two uses of the peristaltic pump.
It will also be understood that because of the presence of the plate and the mounting means, it is possible to sele
REFERENCES:
patent: 3447478 (1969-06-01), Clemens
patent: 4178138 (1979-12-01), Iles
patent: 4548553 (1985-10-01), Ferster
patent: 4705464 (1987-11-01), Arimond
patent: 5044902 (1991-09-01), Malbec
patent: 5518378 (1996-05-01), Neftel et al.
Preliminary International Search Report Issued for PCT/FR95/00617.
Bouvier Bernard
Neftel Frederic
Debiotech S.A.
Korytnyk Peter G.
Thorpe Timothy
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