Diaphragm assembly for a pulsating fluid pump - Patents.com

Abstract

A diaphragm assembly for a pulsatile fluid pump includes an edge-mounted flexible diaphragm, the diaphragm configured for cyclical operation between a diastolic mode and a systolic mode. The diaphragm assembly further includes a systolic distribution brace having an inner wall configured to cup a portion of an outer surface of the diaphragm, and a diastolic plate embedded within the diaphragm and mechanically coupled to a portion of the inner surface of the diaphragm. During the systolic mode, a force is applied across a maximum radial extent of the systolic distribution brace around a periphery of the systolic distribution brace to impart tension within the diaphragm. During the diastolic mode, a force is applied across a maximum radial extent of the diastolic plate to impart tension within the diaphragm around a periphery of the diastolic plate.

Description

[Technical field]

[0001] (Related Applications) This application is one of four applications filed on the same day and having Attorney Docket Nos. 4747 / 1001, 4747 / 1002, 4747 / 1003, and 4747 / 1004, each of which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a pulsating fluid pump, and more particularly to a pulsating fluid pump suitable for pumping blood. [Background technology]

[0003] A pulsatile fluid pump is taught in U.S. Patent No. 7,850,593 ("our prior patent") to Douglas Vincent and Matthew Murphy, co-inventors of the present invention. Our prior patent discloses a pump actuated by a linear motor configured to cause reciprocating motion of a flexible membrane, which in turn serves as the walls of a fluid housing coupled to twin spherical valves in such a manner as to implement a pulsatile fluid flow. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 7,850,593 Summary of the Invention [Means for solving the problem]

[0005] According to one embodiment of the present invention, a diaphragm assembly for a pulsatile fluid pump includes an edge-mounted flexible diaphragm having an inner surface for contacting a fluid to be pumped and an outer surface exposed to ambient air, the diaphragm configured for cyclical operation between a diastolic mode and a systolic mode. The diaphragm assembly further includes a systolic distribution brace having an inner wall configured to cup a portion of the outer surface of the diaphragm, the inner wall having a maximum radial extent, and a diastolic plate embedded within the diaphragm, the diastolic plate having a maximum radial extent, and mechanically coupled to a portion of the inner surface of the diaphragm. The maximum radial extent of the systolic distribution brace at its periphery is greater than the maximum radial extent of the diastolic plate. Further, the systolic distribution brace, diastolic plate, and diaphragm are mechanically coupled to one another such that (i) during the systolic mode, the diaphragm protrudes above the periphery of the systolic distribution brace and a force is applied across the maximum radial extent of the systolic distribution brace to impart tension in the diaphragm around the periphery of the systolic distribution brace, and (ii) during the diastolic mode, a force is applied across the maximum radial extent of the diastolic plate to impart tension in the diaphragm around the periphery of the diastolic plate, the different radial extents of the systolic distribution brace and diastolic plate result in different distributions of force on the diaphragm over the course of the two modes to distribute stresses and reduce strain on the diaphragm over the course of the pumping cycle.

[0006] Alternatively or additionally, the diaphragm has a reinforcing layer disposed between the systolic dispersion brace and the diastolic plate.

[0007] Also alternatively or additionally, the systolic distribution brace has a rounded outer edge and the diaphragm is configured to roll beyond a maximum radial extent of the systolic distribution brace and beyond the rounded outer edge.

[0008] Further alternatively or additionally, an inner wall of the systolic distribution brace, which is configured to cup a portion of the outer surface of the diaphragm, is disposed at an obtuse angle.

[0009] Also alternatively or additionally, the diastolic plate has a bevel.Alternatively or additionally, the diastolic plate has a bevel at an angle that generally corresponds to the obtuse angle of the inner wall of the systolic dispersion brace. [Brief description of the drawings]

[0010] The foregoing features of the embodiments will be more readily understood by reference to the following detailed description, taken in conjunction with the accompanying drawings, in which:

[0011] [Figure 1] FIG. 1 is a vertical cross-section of an integrated pump assembly 200, showing a diaphragm assembly 201 mounted to a pump valving assembly 101 in a diastolic mode in which the chamber 102 is filling.

[0012] [Diagram 2] FIG. 2 is a vertical cross-section of the integrated pump assembly 200, showing the diaphragm assembly 201 mounted to the pump valving assembly 101 in the systolic mode with the chamber 102 evacuated.

[0013] [Diagram 3] FIG. 3 is an exploded side perspective view of integrated pump assembly 200 showing pump valving assembly 101, diaphragm assembly 201, and peripheral flange 221a.

[0014] [Figure 4] FIG. 4 is a vertical cross section of the diaphragm 202. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS Definitions. As used within this description and the accompanying claims, the following terms shall have the meanings indicated, unless the context otherwise requires. A "set" includes at least one member. The "diastolic mode" is a phase of operation of a pulsatile pump according to an embodiment of the present invention during which the diaphragm 202 of the pump valve adjustment assembly 101 is pulled away from the chamber 102 to create negative pressure in the third tapered tube 126 but not in the chamber 102, the inlet spherical check valve assembly 110, and the fourth tapered tube 122. "Systolic mode" is a phase of operation of a pulsatile pump, according to an embodiment of the present invention, during which the diaphragm 202 is urged toward the chamber 102 to generate positive pressure in the second tapered tube 116 but not in the chamber 102, the outlet spherical check valve assembly 120, and the first tapered tube 112.

[0016] 1 is a vertical cross-section of an integrated pump assembly 200, showing the diaphragm assembly 201 mounted to the pump valving assembly 101 in a diastolic mode in which the chamber 102 is filled. Among other things, the pump valving assembly 101 includes an inlet spherical check valve assembly 110 and an outlet spherical check valve assembly 120. The integrated pump assembly 200 includes a pump housing 221 that includes a constriction 221b through which a coupler 214 reciprocates as the diaphragm 202 reciprocates. The constriction 221b is configured to maintain the axial integrity of the coupler 214, and is also configured (via physical features such as flattened sides) to maintain the rotational integrity of the coupler 214. The pump valving assembly 101 is discussed in further detail in the related application referenced above, having Attorney Docket No. 4747 / 1001. When the diaphragm 202 is pulled downward (in a direction away from the chamber 102) to cause filling of the chamber 102, this creates a negative pressure that draws fluid into the chamber 102 through the inlet port 111. Similarly, when the diaphragm 202 is pushed upward, in a direction into the chamber 102, this creates a positive pressure that causes fluid to flow out of the chamber 102 through the outlet port 121. (In these figures, like numbered items correspond to similar components across the different figures.)

[0017] Diaphragm 202 with edge mount 202a (consisting of inner surface 202b, stiffening layer 202c, and outer surface 202d) is part of diaphragm assembly 201, which includes, among other things, diastolic plate 203, mounting shaft 212, systolic dispersion brace 211, and retention ring 213. Diastolic plate 203 is embedded within diaphragm 202, over stiffening layer 202c, and is mechanically coupled to inner surface 202b of diaphragm 202 and mounting shaft 212. When the diaphragm assembly 201 is pulled downward to fill the chamber 102, the force is transferred through the coupler 214 via the coupler slots 214a to the attachment shaft 212 to the diastolic plate 203, which in turn exerts a force on the reinforcing layer 202c and minimizes stress on the elastomeric inner surface 202b and the elastomeric outer surface 202d of the diaphragm 202. The attachment shaft 212 is also coupled to the systolic distribution brace 211 through the retaining ring 213. The outer diameter of the diastolic plate 203 is smaller than the inner diameter of the rounded outer edge 211a of the systolic distribution brace 211. The construction of the diaphragm assembly 201 is therefore not symmetrical with respect to pulling and pushing. During pulling, stress is placed on a more concentrated portion of the diaphragm 202 (defined in large part by the diameter of the diastolic plate 203) through the mounting axis 212 and the diastolic plate 203 than during pushing, which occurs over a larger area through the mounting axis 212 and the systolic distribution brace 211, which has a larger diameter than the diastolic plate 203 and is configured to cup the diaphragm 202.

[0018] Throughout its expected service life, the diaphragm 202 must withstand millions of strokes. With each stroke, the diaphragm 202 is subjected to physical movement and oscillation between positive and negative pressures in the chamber 102. To increase the average service life, an ideal diaphragm 202 should be as thin as possible, since a thin material minimizes bending stresses during flexure. The thin elastomeric material used for the inner surface 202b and outer surface 202d of the diaphragm 202 has excellent flexibility, but low tensile strength. This low tensile strength causes the elastomeric material to overstrain and ultimately fail during the oscillating positive and negative pressures experienced during operation. The reinforcing layer 202c provides the tensile strength required to withstand these pressure fluctuations while maintaining the flexibility of the elastomeric layers 203 and 202d.

[0019] 2 is a vertical cross-section of integrated pump assembly 200, showing diaphragm assembly 201 mounted to pump valving assembly 101 in systolic mode with chamber 102 evacuated. A systolic dispersion brace 211 is mounted beneath diaphragm 202 and is mechanically coupled to diastolic plate 203 through mounting shaft 212. When the diaphragm assembly 201 is pushed upward to empty the chamber 102, force is transmitted through the coupler 214, via the coupler slots 214a, directly to both the retention ring 213 (and onto the systolic distribution brace 211) and the systolic distribution brace 211, which causes the systolic distribution brace 211 to cup the diaphragm 202 (including the reinforcing layer 202c) and exert a force thereon which, as it wraps around the rounded outer edge 211a of the systolic distribution brace 211, distributes the stress over a varying area of ​​the diaphragm 202, reducing strain on the diaphragm 202 over the course of a pumping cycle, thereby increasing its service life.

[0020] 3 is an exploded perspective side view of integrated pump assembly 200, showing pump valving assembly 101, chamber 102, inlet port 111, first tapered tube 112, second tapered tube 116, outlet port 121, fourth tapered tube 121, outlet rib 125, third tapered tube 126, diaphragm assembly 201, diaphragm 202 with edge mount 202a (comprising inner surface 202b, reinforcing layer 202c, and outer surface 202d), pump housing 221 (with peripheral flange 221a, constriction 221b), and compliant member 221c. Items 101-126 are discussed in further detail in the related application referenced above, having Attorney Docket No. 4747 / 1001.

[0021] FIG. 4 is a vertical cross-section of diaphragm 202 (consisting of edge mounting portion 202a, inner surface 202b, reinforcing layer 202c, and outer surface 202d), also showing diastolic plate 203 and attachment axis 212.

[0022] The structure of the pulsatile pump, according to various embodiments of the present invention, can usefully reflect the attributes of the human heart. The human heart is preload sensitive, in that it cannot "pull" blood into the left ventricle, but can only allow available blood to flow naturally into the ventricle. The human heart is also afterload sensitive, in that it responds to compliance and resistance in the downstream vasculature and does not exert excessive forces on the blood that could damage the vasculature. Finally, the left ventricle cannot deliver blood that is not in the ventricle when it contracts, and the bolus of blood it can deliver is limited.

[0023] The pump valving assembly 101 has similar inherent safety attributes, being preload and afterload sensitive, which means it is limited both in the volume of blood it can deliver and the force with which it can deliver that bolus of blood. When filled, the pump valving assembly 101 allows gravity filling from an intravenous reservoir and exerts minimal negative pressure. When a chamber in the pump valving assembly 101 is emptied, the linear motor that powers the pump valving assembly is limited by design. As a result, the pump valving assembly cannot exert undue pressure on the downstream tubing or vasculature, and instead delivers less than the volume of blood in the pump chamber 102, thereby delivering only as much as the vasculature can accommodate.

[0024] The pump valving assembly 101 resembles the left ventricle of the human heart, the inlet spherical check valve assembly 110 used in various embodiments herein resembles the mitral valve, and the outlet spherical check valve assembly 120 used in various embodiments herein resembles the aortic valve. As in the human heart, the inlet 110 and outlet 120 spherical check valve assemblies are passive and require a slight reversal of flow to close. This slight reversal of flow mimics the slight reversal that occurs when the aortic valve of the human heart closes.

[0025] The embodiments of the invention described above are intended to be merely exemplary, and numerous variations and modifications will be apparent to those skilled in the art. All such variations and modifications are intended to be within the scope of the present invention, as defined in any appended claims.

Claims

1. 1. A diaphragm assembly for a pulsating fluid pump, comprising: an edge-mounted flexible diaphragm having an inner surface for contacting a fluid to be pumped and an outer surface exposed to ambient air, said diaphragm being configured for cyclical operation between a diastolic mode and a systolic mode; a systolic distribution brace having an inner wall having a maximum radial extent and configured to cup a portion of an outer surface of the diaphragm; a diastolic plate embedded within the diaphragm, having a maximum radial extent, and mechanically coupled to a portion of an inner surface of the diaphragm; Equipped with a maximum radial extent of the systolic distribution brace at its periphery is greater than a maximum radial extent of the diastolic plate, and the systolic distribution brace, the diastolic plate, and the diaphragm are mechanically coupled to one another, such that (i) during the systolic mode, the diaphragm protrudes above a periphery of the systolic distribution brace and a force is applied across a maximum radial extent of the systolic distribution brace to impart tension in the diaphragm around a periphery of the systolic distribution brace; (ii) during the diastolic mode, a force is applied across a maximum radial extent of the diastolic plate to impart tension within the diaphragm about the periphery of the diastolic plate, the different radial extents of the systolic distribution brace and the diastolic plate resulting in a different distribution of force on the diaphragm over the course of the two modes to distribute stress on the diaphragm and reduce strain on the diaphragm over the course of a pumping cycle. Diaphragm assembly.

2. The diaphragm assembly of claim 1 , wherein the diaphragm includes a reinforcing layer disposed between the systolic distribution brace and the diastolic plate.

3. 2. The diaphragm assembly of claim 1, wherein the systolic distribution brace has a rounded outer edge, and the diaphragm is configured to roll beyond a maximum radial extent of the systolic distribution brace and beyond the rounded outer edge.

4. The diaphragm assembly of claim 1 , wherein an inner wall of the systolic distribution brace configured to cup a portion of an outer surface of the diaphragm is disposed at an obtuse angle.

5. The diaphragm assembly of claim 1 , wherein the diastole plate has a bevel.

6. The diaphragm assembly of claim 1 , wherein the diastolic plate has a bevel at an angle that generally corresponds to an obtuse angle of an inner wall of the systolic distribution brace.

Images