Pumps – Condition responsive control of drive transmission or pump... – Adjustable cam or linkage
Reexamination Certificate
1999-08-09
2001-05-01
Thorpe, Timothy S. (Department: 3746)
Pumps
Condition responsive control of drive transmission or pump...
Adjustable cam or linkage
Reexamination Certificate
active
06224346
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to fluid pumps. More particularly, the invention concerns a fluid pump for precisely controlling the transfer of medicaments and other beneficial agents from a source of fluid to a patient.
2. Discussion of the Prior Art
A number of approaches have been suggested in the past for delivering fluid medicaments and other beneficial agents to a patient. The most common apparatus for this purpose is the so-called “gravity feed system”. This system involves the use of a flexible bag that is supported above the patient and contains the fluid to be delivered. The fluid is delivered to the patient by force of gravity via a flexible tube that extends between the bag and the patient. The rate of fluid flow to the patient from the bag is basically a function of the amount of restriction of the tube leading to the patient.
To more precisely and reliably control the rate of fluid flow to the patient, several types of devices have been proposed. These devices are generally either mechanical or electronic. Exemplary of one prior art mechanical type delivery device is that described in U. S. Pat. No. 3,464,359 issued to King et al. The King et al device comprises a fluid pump for moving fluid from one system to another under pressure and includes means to assert positive control over the flow rate and also to isolate the outlet of the pump from small quantities of air occurring therein. The device basically comprises a pump body having a central chamber provided with an inlet and an outlet port. Pistons are associated with each port and are movable within the central chamber between a port open and port closed positions. The pistons are constructed and arranged so as to move fluid from one system, through the inlet port of the pump, to the central pump chamber of the pump, toward the outlet port of the pump and then into the second system.
Another prior art mechanical pumping device is disclosed in U.S. Pat. No. 5,163,822 issued to Koelln. The Koelln device comprises a radial piston pump having a pump body with two pump chambers disposed in a straight line. Pistons reciprocate within the pump chambers and are coupled to an actuator that is rotatable about an axis which bisects the straight line and functions to reciprocate the pistons in opposite directions. Each pump chamber is connected to an intake fluid duct and a discharge fluid duct. The inlet ducts are connected to a common main intake duct and the discharge fluid ducts are connected to a common main discharge duct. The actuator controls the operating components of the apparatus and cooperates with the valves thereof, which function to open and close the valve ducts.
In addition to mechanical type pumping devices, a number of different types of micro processor controlled, electronic pumps have been proposed for the controlled delivery of various medicaments to a patient. Exemplary of one prior art pump of this type is that described in U. S. Pat. No. 5,069,668 issued to Boydman. The pump there described is of a character that is capable of receiving a wide variety of commands as by pushing buttons or other controls in conjunction with viewing a changing display of information that is presented on a screen and of carrying out the entered commands as by causing the pumping mechanism to dispense a series of carefully timed, precisely determined quantities of liquid medicine from a reservoir. As a general rule, electronic pumps tend to be complex and are usually quite expensive.
The thrust of the present invention is to provide an elegantly simple fluid pump suitable for the reliable transfer to a patient of liquids such as intravenous solutions and liquid medicaments at precisely controlled flow rates.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a simple, compact and highly efficient fluid pump for delivering a wide variety of fluids from a fluid source to a remote location as, for example, to a patient at precisely controlled flow rates.
Another object of the invention is to provide an apparatus of the aforementioned character, which is highly reliable in operation and one, which maintains an accurate and stable fluid flow from the source of the fluids to the patient.
Another object of the invention is to provide a pumping apparatus of the character described in the preceding paragraphs in which no valves are required to control fluid flow toward and away from the pumping apparatus.
Another object of the invention is to provide a fluid pump of the class described in which the volume of fluid transferred from the source of fluid to the patient can be varied and closely controlled to enable fluid delivery to the patient at very low flow rates.
Another object of the invention is to provide a fluid pump of the character described in the preceding paragraphs which is made up of relatively few component parts, is economical to manufacture, is easy to use and requires minimum maintenance.
By way of summary, one form of the apparatus of the invention for moving fluid from a first location to a second location comprises a housing containing a pump body having a central passageway with a fluid inlet and first and second fluid outlets in communication with the passageway. A shuttle having first and second fluid chambers is movable within the passageway of the body between first and second positions. First, second, third, and fourth generally annular shaped fluid passageways provided in the shuttle permit selective fluid communication between the first and second fluid chambers of the shuttle and the inlet and outlet ports of the pump body. First and second inlet passageways provided in the shuttle permits selective fluid communication between the inlet of the pump body and the first and second fluid chambers of the shuttle. A piston is reciprocally movable within the shuttle chambers by a uniquely configured operating means, such as a cam ring. The reciprocation piston functions, not only to control fluid flow through the shuttle, but also functions to move the shuttle between its first and second positions within the central passageway of the pump body. With the novel construction thus described, fluid is expelled from the first chamber of the shuttle as the piston moves from a first position toward a second position and, at the same time, fluid is aspirated from the fluid source into the second chamber of the shuttle. During pumping operations, fluid is expelled from the second chamber of the shuttle as the piston moves from the second position toward the first position and fluid is simultaneously aspirated from the fluid source into the first chamber of the shuttle. With this unique arrangement, each movement of the piston permits a precise, known volume of fluid to be expelled from one chamber of the shuttle and at the same time accomplishes the controlled aspiration into the other chamber of a fixed volume of fluid from the fluid source.
REFERENCES:
patent: 3464359 (1969-09-01), King et al.
patent: 5044900 (1991-09-01), Cavallaro
patent: 5069668 (1991-12-01), Boydman
patent: 5163822 (1992-11-01), Koelin
patent: 5277338 (1994-01-01), Divall
Brunton, Esq. James E.
Medimop Medical Projects Ltd.
Rodriguez William
Thorpe Timothy S.
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