Low power electromagnetic pump

• US 6,193,477 B1
• Filed: 06/29/1999
• Issued: 02/27/2001
• Est. Priority Date: 03/11/1994
• Status: Expired due to Term

• Current Assignee: Medallion Therapeutics, Inc.
• Original Assignee: Wilson Greatbatch Technologies, Inc.
• Inventors: Gillies, Douglas K., Morris, Lawrence E., Frenz, Norbert W. Jr., Falk, Theodore J., Brown, W. Richard, Konopa, Raymond S.
• Primary Examiner(s): Walberg, Teresa
• Assistant Examiner(s): FASTOVSKY, LEONID M
• Application Number:
  US09/342,372
• Time in Patent Office: 609 Days
• Field of Search: 417/415, 417/416, 417/417
• US Class Current: 417/415
• CPC Class Codes: A61M 5/14216 Reciprocating piston type
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: F04B 11/0091 using a special shape of fluid pass, e.g. throttles, ducts
• CPC Class Codes: F04B 17/042 the solenoid motor being separated from the fluid flow
• CPC Class Codes: F04B 19/06 Pumps for delivery of both liquid and elastic fluids at the same time wet gas pumps F04B37/20
• CPC Class Codes: F04B 2205/063 in a reservoir linked to the pump outlet
• CPC Class Codes: F04B 2205/503 of gas in a liquid flow, e.g. gas bubbles
• CPC Class Codes: F04B 49/243 by keeping open the inlet valve
• CPC Class Codes: F04B 53/1032 Spring-actuated disc valves F04B53/1022, F04B53/103 take precedence
• CPC Class Codes: F05C 2201/046 Stainless steel or inox, e.g. 18-8

Abstract

All electromagnetic pump comprising a housing having fluid receiving and pumping chambers in communication with an inlet and outlet, respectively, an electromagnet carried by the housing external to the fluid chambers thereof, and an armature movable in the housing having a pole portion magnetically attracted by the electromagnet and a piston portion to force fluid out of the chambers and through the pump outlet. A path provides controlled bypass for bubbles in the fluid around the armature piston portion between the fluid pumping chamber and the fluid receiving chamber only during the return stroke of the armature.

Fluid inertial effect is reduced by an outlet orifice provided in the fluid path from the pump outlet and by a bypass orifice in the fluid bypass path, the outlet and bypass orifices being provided either individually or in combination depending upon the fluid flow characteristics of the system of which the pump is a part. An accumulator between the pump outlet and a catheter leading away from the pump alleviates inertial and viscous effects from the catheter. The armature pole portion has a fluid-contacting section of material which is compatible with and corrosion resistant to the fluid, and can be a body of magnetic material within a titanium enclosure or a body of chrome-molybdenum-iron alloy. The check valve and inlet are so arranged that the pump displacement can be reduced without reducing bubble pumping capability.

Claims

1. An electromagnetic pump comprising:

a) a housing having an interior fluid containing region including a fluid receiving chamber and a fluid pumping chamber in fluid communication therewith, an inlet in fluid communication with said receiving chamber and an outlet in fluid communication with said pumping chamber;

b) check valve means operatively associated with said fluid containing region for allowing fluid flow in a direction from said inlet through said outlet and blocking fluid flow in a direction from said outlet through said inlet;

c) electromagnet means carried by said housing and located external to said fluid containing region;

d) an armature positioned in said fluid containing region of said housing having a pole portion located for magnetic attraction by said electromagnet means and having a piston portion operatively associated with said fluid receiving and pumping chambers for forcing fluid from said receiving chamber through said outlet, said armature being movably supported in said housing for movement from a rest position through a forward pumping stroke when attracted by said electromagnet means to force fluid from said receiving chamber through said outlet and for movement in an opposite direction through a return stroke back to said rest position, said armature piston portion being located between a plunger portion and said pump inlet and movable within said housing, there being a relatively small clearance between said armature piston portion and said housing;

e) means defining a magnetic circuit including said electromagnet means and said armature and a gap between said pole portion of said armature and said electromagnet means for moving said armature toward said electromagnet means to close said gap in response to electrical energization of said electromagnetic means;

f) means extending from said outlet for providing a path for fluid flow from said pump; and

g) means in said fluid flow path for providing an orifice in the path of fluid flow from said outlet so as to reduce the effect of the momentum of the fluid stream through the pump on the volume of fluid delivered during each pump cycle.

2. A pump according to claim 1, wherein said means for providing a fluid flow path from said pump comprises relatively rigid tubing connected at one end to said pump outlet and wherein said orifice providing means is located adjacent the other end of said tubing.

3. A pump according to claim 2, wherein said orifice providing means is at a location which insures that fluid pressure within the pump remains positive during deceleration of said piston during the forward pumping stroke.

4. A pump according to claim 1, wherein the pulse volume of the pump is from about 0.4 μ

L to about 0.6 μ

L and the diameter of said orifice is about 0.0055 inch.

5. An electromagnetic pump comprising:

a) a housing having an interior fluid containing region including a fluid receiving chamber and a fluid pumping chamber in fluid communication therewith, an inlet in fluid communication with said receiving chamber and an outlet with said pumping chamber;

b) check valve means operatively associated with said fluid containing region for allowing fluid flow in a direction from said inlet through said outlet and blocking fluid flow in a direction from said outlet through said inlet;

c) electromagnet means carried by said housing and located external to said fluid containing region;

d) an armature positioned in said fluid containing region of said housing having a pole portion located for magnetic attraction by said electromagnet means and having a piston portion operatively associated with said fluid receiving and pumping chambers for forcing fluid from said receiving chamber through said outlet, said armature being movably supported in said housing for movement from a rest position through a forward pumping stroke when attracted by said electromagnet means to force fluid from said receiving chamber through said outlet and for movement in an opposite direction through a return stroke back to said rest position, said armature piston portion being located between a plunger portion and said pump inlet and movable within said housing, there being a relatively small clearance between said armature piston portion and said housing;

e) means defining a magnetic circuit including said electromagnet means and said armature and a gap between said pole portion of said armature and said electromagnet means for moving said armature toward said electromagnet means to close said gap in response to electrical energization of said electromagnetic means;

f) catheter means for providing a path for fluid flow away from said pump;

g) accumulator means connected in fluid communication with one end of said catheter means; and

h) means for placing said accumulator means in fluid communication with said outlet of said pump.

6. A pump according to claim 5, wherein said accumulator means has sufficient compliance to receive the entire volume of a single pump stroke with a pressure increase low enough so that operation of said pump is not disturbed.

7. A pump according to claim 5, wherein said accumulator means has compliance low enough so that moderate back pressure builds up within said accumulator means during a pump stroke.

8. A pump according to claim 5, wherein said catheter means is of a dimension such that the volume of a single pump stroke is completely discharged from said accumulator means between pump strokes.

9. A pump according to claim 5, wherein said accumulator means and said catheter means are dimensioned so as to be critically damped by viscous flow through said catheter means.

10. A pump according to claim 5, further including means for providing an outlet orifice between said pump outlet and said accumulator means.

11. A pump according to claim 5, further including:

a) controlled means for providing a bypass path for bubbles in the fluid around said armature piston portion between said fluid pumping chamber and said fluid receiving chamber only during said return stroke of said armature; and

b) means in said bypass path for providing an orifice for fluid flow in the bypass path so as to decelerate the flow of fluid through the pump and limit the inertial flow volume in the pump.