Pumps – Motor driven – Electric or magnetic motor
Patent
1981-05-15
1984-03-20
Look, Edward K.
Pumps
Motor driven
Electric or magnetic motor
3 17, 251 65, 417505, 604152, F04B 1704
Patent
active
044378157
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a pump and to an apparatus incorporating such a pump for infusing into a subject determined quantities of liquid medicine at pre-determined time intervals.
The invention has particular, but not exclusive, relevance to medical applications in which controlled doses of drugs must be administered over long periods of time. For instance, persons suffering from diabetes melitus require routine administration of insulin, which is normally given by self-injection. Not only does this raise problems of maintaining supplies of sterile needles and the like, but the use of injections tends to limit administration to once or twice daily, and the resulting concentration of insulin in the blood fluctuates widely.
In this and other applications, there is a need for a means of infusing drugs at a controlled rate so as to give relatively small amounts at relatively frequent intervals, say one to four times per hour. Such frequency would preclude conventional injection.
Objects of the invention is therefore to provide a pump suitable for use in such infusion, and an infusion apparatus incorporating the pump.
According to the first aspect of the present invention, I provide a pump comprising a casing defining an elongate chamber, inlet and outlet valves communicating with the chamber, a piston coaxially movable in the chamber, and an electromagnet controlling movement of the piston via an armature, the outlet valve also being controlled by the electromagnet via a valve armature;
characterised in that the inlet and outlet valves are balls made from a material having ferromagnetic properties and seats made of non-magnetic material and magnets tensioning the balls of said inlet and outlet valves against their seats when in a closed position, and in that power means for opening said balls from their seats, comprise for said inlet valve a force equivalent to a hydraulic force caused by coaxial movement of the piston in the chamber, said piston and said outlet valve being operated against the flow of liquid by the excitation of the single electromagnet, a piston lock magnet providing a biasing force on the piston thereby to inhibit unintentional movement of the piston, and said outlet valve remaining closed in response to adverse inlet or outlet pressure conditions to prevent inadvertent flow of liquid.
According to a second aspect of the present invention, I provide an apparatus for infusing into a subject determined quantities of liquid medicine at pre-determined time intervals, the apparatus comprising a pump in accordance with the preceding paragraph in combination with a reservoir, the pump further including at least one non-return valve for passing liquid pumped from the reservoir to a cannula for infusing the liquid into a subject, and the circuitry including timing means for actuating the piston at predetermined regular intervals.
Preferably, two electromagnet coils are wound around the casing of the pump.
Preferably also, the apparatus together with the cannula are implantable into the living tissue or cavities of the subject.
An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a lengthwise cross-section of a pump according to the present invention;
FIGS. 2 to 5 are respectively cross-sectional views of the pump along the lines II--II, III--III, IV--IV and V--V of FIG. 1, the views being to the same scale which is larger than that in FIG. 1; and
FIGS. 6A and 6B are respectively a plan view and an end view of an apparatus according to the present invention of a size implantable into the living tissue or cavities of a subject.
Referring to FIGS. 1 to 5 of the drawings, a pump comprises a cylindrical casing 10 whose interior defines an elongate chamber 11. A piston 12 is co-axially movable in said chamber 11. The piston 12 is an assembly comprising a tube 12A which has on its outside circumference two similar rings 14 integral therewith and spaced apart on and proud of its surface. Each ring 14 is adjacent t
REFERENCES:
patent: 2597952 (1952-05-01), Rosenlund
patent: 2925814 (1960-02-01), Vibber et al.
patent: 2962593 (1960-11-01), Thomas
patent: 3205787 (1965-09-01), Volkmann
patent: 3437044 (1969-04-01), Sanders et al.
patent: 3874822 (1975-04-01), Nakamura
patent: 4159026 (1979-06-01), Williamson
patent: 4274407 (1981-06-01), Scarlett
Baker Joseph J.
Ferguson Jr. Gerald J.
Look Edward K.
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