US3496874A - Diaphragm actuated pulse pump - Google Patents

Description

Feb. 24, 1%70 s. FINDLAY 3,496,874

I DIAPHRAGM ACTUATED PULSE mar I Filed April 16, 1968 2 Sheets-Sheet 1 INVE/V7'O2 Magma 1 W J abw 2 I 5y 47-70225?! F 24, 1970 J. S. FINDLAY DIAPHRAGM ACTUATED PULSE PUMP Filed April 16, 1968 United States Patent U.S. Cl. 10338 9 Claims ABSTRACT OF THE DISCLOSURE A pulse pump construction for blood and the like in which a piston and cylinder device operates through a flexible diaphragm to create pressure variations in a pumping chamber. The diaphragm is cup-shaped with its concave side facing the pump chamber to reduce pockets which might trap blood. Means are provided for varying the stroke of the piston from a maximum displacement to and including zero displacement while the effectiveness of the pumping action is maintained as the amplitude of the stroke is varied. Means are provided for adjusting the ratio of the stroke of the piston in one direction versus the stroke of the piston in the opposite direction to adjust the contraction-expansion ratio of the diaphragm. A housing for the pump has a removable base member with a portion of the pump chamber formed in the base member and with the diaphragm being held in position by the base member. An inlet and an outlet to and from the pump chamber are disposed in the removable base member, and the base member is symmetrical in design to permit mounting on the housing in opposite orientations to reverse the flow of blood through the pump chamber SUMMARY OF THE INVENTION This invention relates to a pulse pump for blood and is intended as a supplement to or a substitute for the heart in circulating blood. In order to fulfill this function, certain features are important as set forth below.

The principal object of this invention is to provide a new and improved pulse pump for circulating blood and the like.

The pulse pump of this invention includes a piston which reciprocates in a cylinder formed in a housing above a pump chamber. A cup-shaped diaphragm extends across the center of the chamber and is caused to flex upwardly and downwardly in accordance with movement of the piston. Check valves are positioned at an inlet and an outlet to the pump chamber to control in-flow and outflow of the blood. The piston is reciprocated by a motor driven crank, and the motor is of variable speed to vary the pumping rate. The piston is pivotally secured to the free end of the crank and the pivot point or fulcrum of the crank is adjustable so that the length of stroke of the piston may be varied.

An important feature of the pulse pump set forth in the preceding paragraph is that the fulcrum may be moved all the way to the end of the crank so that a condition of zero piston displacement is achieved to permit transferring the pumping operation from one pump to another.

Another feature of this invention is that the ratio of the stroke of the piston in one direction versus the stroke of the piston in the opposite direction is adjustable to adjust the contraction-expansion ratio of the diaphragm which simulates the systolic and diastolic cycle of a heart.

A further feature of this invention is that the center of the piston stroke moves toward the diaphragm as the amplitude of the stroke is increased.

3,496,874 Patented Feb. 24, 1970 Still another feature of this invention is that each of the check valves which control the in-flow and the outflow of the blood at the pump chamber is comprised of a conical, three leaved flexible member, the walls of the leaves being tapered from the base toward the apex of the cone so that the valve opens and closes easily without damage to the blood even with small flow rates.

Yet a further feature of this invention is that the diaphragm is cup-shaped with the concave surface of the diaphragm facing toward the pump chamber to reduce pockets which might trap blood and where the blood might clot.

Further features, objects, and advantages of the invention will be set forth in the following detailed description taken in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIGURE 1 is a side elevational view of a pulse pump embodying the invention, with the housing for the pump chamber in section;

FIG. 2 is a cut-away section taken generally along the line 22 of FIG. 1;

FIG. 3 is a partial elevational view of the concentric drive means of FIG. 1, with the pivot for the crank arm adjusted to shorten the piston stroke;

FIG. 4 is a view similar to that of FIG. 3, with the drive means adjusted to zero piston displacement;

FIG. 5 is a section taken generally along the line 55 of FIG. 4;

FIG. 6 is a section taken generally along the line 6-6 of FIG. 3; and

FIG. 7 is an elevational View showing a modified form of means for adjusting the piston stroke.

DETAILED DESCRIPTION OF THE INVENTION Referrng to the drawings, the device of this invention is shown as comprising a pulse pump which is intended as a substitute for a heart in circulating blood. The device includes a framework generally designated 10 on which the pump chamber, drive means and control elements of this invention are mounted. The framework 10 includes upper support braces 11, lower support braces 12, and vertical supporting legs 13. The pulse pump is operated by a motor M which has a variable speed which may be controlled to vary the pumping rate.

A housing block 14 (FIG. 1), having a lower removable base portion 14A, is mounted by bolts 16 to the horizontal support brace 12. The housing block 14 and base portion 14A have facing recesses which combine to form a pumping chamber 18 which has inlet and outlet passages 20 and 22, respectively. Appropriate check valve assemblies, generally designated 24, are disposed in the inlet and outlet passages to control the inflow and out-flow of the blood. These check valves 24 are shown in detail in FIG 2 and will be described in greater detail hereinafter. At this point, it should be pointed out that the removable base portion 14A of the housing block 14 is symmetrical and secured to the housing block by a plurality of bolts 26 symmetrically arranged so that the base portion can be mounted on the housing in opposite orientations to reverse the flow of blood in relation to the portion of the pump chamber 18 formed by the upper housing block 14.

A piston 28 is reciprocated by the motor M in a cylinder 30 formed in the housing block 14 above the pump chamber 18. The housing block 14 has an annular extension 32 extending through an opening 34 in the horizontal support brace 12 to form an upward extension of the cylinder 30. The piston 28 is mounted on the lower end of a piston rod 36. A cup-shaped flexible diaphragm 38 of rubber or like material extends across the pump chamber 18 and creates pressure variations in the pump chamber in response to reciprocation of the piston 28 to draw the blood in through the inlet passage 20 and force the blood out through the outlet passage 22. The diaphragm has a peripheral lip 38A which is clamped between annular complementary recesses formed in the housing block 14 and base portion 14A. The concave surface of the diaphragm 38 faces the pump chamber to reduce pockets which might trap blood and where the blood might clot. The diaphragm 38 is easily removed for cleaning or replacement by simply removing the housing base portion 14A.

The check valve assemblies 24 which control the flow of blood through the pump chamber 18 are shown in detail in FIG. 2 and each assembly includes a soft flexible valve member 40 which is made of rubber or like material. The valve members 40 are conically shaped and are slit to provide a three-leaf configuration. The walls of the leaves are tapered from the base toward the apex of the cone so that the valve opens and closes easily, without damage to the blood, even with small flow rates. As with the diaphragm 38', these valve members are designed to minimize areas where blood flow can stagnate and clot. The valve members 40 include marginal lips 40A which are clamped in annular recesses in the housing base portion 14A by abutment members 42, each of which has an annular shoulder 42A engaging the lip 40A of the valve member 40. Each of the abutment members 42 has a nipple portion 42B for receiving appropriate tubing. The abutment members are held in place by sleeve members 44 "which engage the shoulders 42A and which are threaded into appropriate bores in the housing base portion 14A.

The piston 28 and piston rod 36 are reciprocated by the motor M through a crank or rocker arm 46 which is concentrically fixed pivotally to a disc-shaped rotating member 48 operated by the motor M. The upper end of the piston rod 36 is pivotally secured to the free end of the crank 46, as illustrated best in FIGS. 1 and 5. The crank 46 is pivoted on a pivot bracket 50 which forms a fulcrum for the crank.

The fulcrum 50 is movably adjustable in a direction normal to the piston rod 36 to vary the stroke of the piston 28 and thus the volume of blood pumped on each stroke of the piston. This is accomplished by providing grooves 52 extending longitudinally along the crank 46 and pins 54 which are fixed to the base of the pivot bracket 50 and which extend into the grooves 52 in a manner best illustrated in FIG. 5. A worm gear 56 (FIG. 6), which is rotated by a control knob 58 on the front of the frame 10, moves the pivot bracket 50 normal to the piston rod 32 to move the pins 54 in the grooves 52 longitudinally of the crank arm 46. The worm gear 56 is threaded into a shaft member 60 (FIGS. and 6) extending upwardly from the pivot bracket 50. As the control knob 58 is turned to rotate the worm gear 56, the shaft '60 and the pivot bracket 50 are moved linearly along the worm gear in a direction normal to the piston rod 36. The pivot bracket 50 moves in a bracket housing 62 and when the bracket is moved to a position corresponding to the desired piston displacement, a tightening knob '64 which is threaded on the upper end of shaft 60 may be utilized to hold the pivot bracket in place. It can be seen that as the pivot bracket 50, which forms the fulcrum for the crank 46, moves to the right as viewed in FIG. 1 to a position closer to the piston rod 36, the lever arm formed by the crank on the right of the pivot bracket 50 is shortened and consequently the stroke of the piston is shortened. This can be seen by comparing the position of the pivot bracket 50 shown in FIG. 1 with that shown in FIG. 3. In FIG. 3, the pivot bracket 50 is closer to the piston rod 36 and thus results in a shorter piston stroke.

Referring to FIG. 4, an important feature of the blood pump of this invention is that the fulcrum formed by the pivot bracket 50 may be moved all the way to a position where the pins '52 on the pivot bracket 50* are disposed in the slots 52 in vertical alignment with the piston rod 36 so that a condition of zero piston displacement is achieved while still maintaining the piston rod operatively connected to the motor M. The reduction of the piston stroke to zero permits the transfer of the pumping operation from one pump to another. It should also be pointed out that as the stroke of the piston increases, the center of the piston stroke moves toward the diaphragm reducing the volume of air between the diaphragm and the piston. There is suflicient leakage around the piston so that the volume of air between the piston and diaphragm adjusts automatically.

Another feature of the pulse pump of this invention is that means are provided for adjusting the ratio of the piston stroke in one direction versus the piston stroke in the opposite direction to thereby adjust the contractionexpansion ratio of the diaphragm 38- which corresponds to the systolic and diastolic cycle of a heart. This is accomplished by mounting the motor M on the horizontal supporting brace 10 by a plurality of bolts 70 (FIG. 1) which extend through longitudinal slots 72 in the brace 12. The position of the motor with respect to the pivot bracket 50 can be varied by loosening the bolts 70 and moving the motor along the brace 12. The left-hand end of the crank 46 has a slot 74 which receives a pin 76 to accommodate the movement of the motor. In order to comprehend how the movement of the motor adjusts the stroke ratio of the piston, it would be helpful to visualize imaginary lines drawn from the pivot point (of pivot bracket 50) tangentially to opposite sides of the rotating disc 48. It can be seen that the closer the motor M is to the pivot bracket 50 the shorter would be the are on the periphery of the disc between the points where these two imaginary lines would meet the disc. This are would correspond to one stroke of the piston while the are about the remainder of the disc would correspond to the opposite stroke of the piston. Vice versa, as the motor is moved to the left in FIG. 1 away from the pivot bracket 50 the ratio of the strokes of the piston would more closely approach a 5050 ratio.

Referring to FIG. 7, it can be seen that by inclining the worm gear 56 in the manner shown, the pivot bracket '50 is lowered toward the diaphragm as the length of the piston stroke is shortened. Thus, with this arrangement, the center of the piston stroke will move towards the diaphragm as the amplitude of the stroke is decreased. This is desirable so that the air space between the diaphragm and the piston does not damp the diaphragm action with extremely short piston strokes.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefromas some modifications will be obvious to those skilled in the art.

I claim:

1. A pulse pump, including a housing having a pump chamber and a cylinder therein, a flexible diaphragm between the chamber and one end of said cylinder, a piston mounted on a piston rod for reciprocating movement in opposite directions in said cylinder to expand and contract said diaphragm, drive means operatively connected to said piston rod for reciprocating the piston within the cylinder, the improvement comprising means for adjusting the stroke of said piston between a predetermined maximum displacement to and including zero displacement while maintaining the drive means operatively connected to the piston.

2. The pulse pump of claim 1 wherein said adjusting means effects a change in the center of the piston stroke as the displacement of the piston increases.

3. The pulse pump of claim 1 wherein said adjusting means changes the center of the piston stroke toward said one end of the cylinder as the displacement of the piston decreases to prevent the air in the space between,

the piston and the diaphragm from damping the diaphragm action for piston strokes of small amplitude.

4. The pulse pump of claim 1 wherein said drive means includes a rotating member, and including a concentric link means comprising a crank arm pivotally connected at one end to said rotating member and at the other end to said piston rod, a pivot bracket pivotally secured to said crank arm intermediate the ends of the crank arm so that rotation of said member oscillates the other end of the crank arm to reciprocate the piston in response to rotation of said member, and means for adjusting said pivot bracket along said crank arm to and including a point in alignment with the axis of said piston rod to effect zero piston displacement.

5. The pulse pump of claim 1 including means for adjusting the ratio of the stroke of said piston in one direction versus the stroke of the piston in the opposite direction to thereby adjust the contraction-expansion ratio of said diaphragm.

6. The pulse pump of claim 5 wherein said drive means includes a rotating member, and including a concentric link means comprising a crank arm pivotally connected at one end to said rotating member and at the other end to said piston rod, a pivot bracket secured to said crank arm intermediate the ends of the crank arm so that rotation of said member oscillates said other end of the crank arm, said one end of the crank arm having a slot for receiving a pin on said rotating member, and means for moving said rotating member toward and away from said pivot bracket.

7. In a pulse pump for blood and the like including a housing having a pump chamber with an inlet and an outlet for the passage of blood through the chamber and having a removable base member with a portion of said pump chamber formed therein, check valve means for directing the flow of blood through said inlet into said chamber and out of said chamber through said outlet, and means in communication with said pump chamber for creating pressure variations in the chamber to draw the blood in through said inlet and force the blood out through said outlet, the improvement in which said inlet and said outlet are disposed in said base member, said base member being symmetrical and mountable on said housing in opposite orientations to reverse the flow of liquid through said chamber.

8. A pulse pump comprising a housing having a pump chamber; a pair of passages extending through the wall of the housing for flow of liquid through the chamber, each of said passages having an inner portion of a first diameter adjacent said chamber and an outer portion of a larger diameter with a shoulder joining the two portions; 2. check valve in each of said passages to direct the flow of liquid into said chamber through one passage and out of said chamber through the other, the check valve having a flexible one-way valve portion, and an outwardly directed marginal lip extending circumferentially therearound, said marginal lip being engageable with the shoulder at the inner end of each passage for flow of liquid through said chamber in either direction; abutment means to clamp said check valves in each passage, and having a portion for connection to each of said passages; and means connected with said pump chamber for creating pressure variations in the chamber to draw liquid in through the selected input and force liquid out through the selected output.

9. A pulse pump construction, comprising a housing having a pump chamber, an inlet and an outlet for the passage of liquid through the chamber, check valve means associated with each of said inlet and said outlet to direct the flow of liquid through said inlet into said chamber and out of said chamber through said outlet, and means in communication with said pump chamber for creating pressure variations in the chamber to draw liquid in through the inlet and force liquid out through the outlet, in which said means for creating pressure variations includes a flexible diaphragm forming a sealed closure between said last named means and said pump chamber, said diaphragm being cup-shaped with its concave side facing the pump chamber to reduce pockets which might trap blood and where the blood might clot, the improvement in which the direction of flow of liquid through said chamber is parallel to a plane formed by the marginal edge of said cup-shaped diaphragm.

References Cited UNITED STATES PATENTS 2,548,807 4/1951 Morgan et al 103-38 X 2,764,097 9/ 1956 Browne.

2,960,936 11/1960 Dean et a1. 10338 3,127,846 4/1964 Kerns 103152 3,218,979 11/1965 Baldwin 103-38 X 3,327,322 6/1967 Norton 103-38 LEONARD H. GERIN, Primary Examiner US. Cl. X.R.

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