US 4,360,323 A · Proportioning pumping system for dialysis machines

Abstract

A compact and highly reliable proportioning pumping system for supplying a precise and controllable mixture of concentrate and water in a kidney dialysis machine comprises a central body and a pair of oppositely mounted pivotable linkages coupled to the body. A first pivotable linkage is coupled by connecting rods to a water metering piston and a concentrate metering piston respectively, a variable stroke ratio being provided by a signal actuated drive coupled to the linkage mechanism and controlling the relative position of the end of one of the connecting rods. The change of position is advantageously effected so as to maintain a precise proportionality between the flows delivered by each of the pistons throughout their variable stroke lengths. The range of proportioning adjustments can be mechanically limited and alarm conditions can readily be detected. Precise delivery of surge-free flows of liquid for subsequent mixing is enhanced by controlling flow through each piston with a fast-acting metering valve system. A bistable switching valve responsive to the limit positions of the first linkage mechanism controls an actuator piston to operate a second pivotable linkage mechanism to which the metering valves are coupled. The second linkage switches rapidly between two alternate valve positions, so that there is a minimum dead zone and both water and concentrate flows are precisely controlled.

Claims13

Dependent claims

A positive displacement system for delivery of two liquids at controlled rates using at least one pressurized liquid comprising:

first and second reciprocating piston means including first pivotally mounted linkage means coupled to reciprocate said piston means in synchronism, each for pumping a different liquid;
metering valve means including conduit means for controlling liquid flow directions through said piston means in response to the position of said metering valve means;
and control means including reciprocable actuator piston means, and switching valve means, and second pivotally mounted linkage means coupling said actuator piston means to reciprocate the metering valve means, said switching valve means being coupled to said first and second piston means and responsive to the position of said first and second piston means, said switching valve means being coupled to shift between limit positions synchronously with direction changes of said first and second piston means and controlling liquid flow to said actuator piston to shift said piston between limit positions synchronously with selected positions of said first and second piston means and reciprocate more rapidly than said first and second piston means.

A proportioning pump system for providing controlled flows of water and concentrate for a dialysis machine, comprising:

reciprocable actuator means operative in response to water pressure and including a shiftable valve member, said actuator means shifting rapidly between limit positions under control of the position of the shiftable valve member;
water metering piston means reciprocable at a relatively slower rate than said actuator means in response to the direction of flow therethrough of pressurized water;
concentrate metering piston means;
first pivotally mounted linkage means coupling said water metering piston means and said concentrate metering piston means to reciprocate said piston means with a selected stroke length ratio between them;
and coupled to shift said shiftable valve member in timed relation to reciprocation of said piston means;
second pivotally mounted linkage means coupled to said reciprocable actuator means;
metering valve means coupled to said second pivotally mounted linkage means and responsive to the position of said actuator means and coupled to control the direction of water and concentrate flow through the respective piston means;
and
means coupled to at least one of said piston means at the coupling to said first linkage means for varying the stroke length ratio between said piston means.

6 more elements

A proportioning pumping system for a dialysate delivery system supplying water and concentrate in adjustable proportions within a predetermined range of proportions comprising:

a pivotable linkage mechanism;
a water metering piston movable along a first axis and coupled to a source of water and including connecting rod means coupled to a first region of said linkage mechanism;
a concentrate metering piston movable along a line parallel to the first axis and coupled to a source of concentrate and including connecting rod means coupled to said first linkage mechanism at a second region thereof;
means coupled to said linkage mechanism and at least one of said connecting rod means for adjusting the piston stroke ratio of the two pistons;
means coupled to the water and concentrate metering pistons for mixing metered flows from the two pistons;
means coupled to receive the mixed flows for indicating the concentrate proportion in the mixture;
and
means coupled to the means for indicating and responsive to the indication of concentrate proportion and coupled to said means for adjusting for altering the stroke ratios to tend to maintain a constant concentrate proportion.

5 more elements

Dependencies are inferred from the claim text.

Proportioning pumping system for dialysis machines

Life of this patent

Proportioning pumping system for dialysis machines

Life of this patent

Abstract

Claims13