Low power electromagnetic pump

• US 4,636,150 A
• Filed: 06/05/1984
• Issued: 01/13/1987
• Est. Priority Date: 05/23/1983
• Status: Expired due to Term

• Current Assignee: Greatbatch Enterprises, Inc.
• Original Assignee: Greatbatch Enterprises, Inc.
• Inventors: Falk, Theodore J., Morris, Lawrence E.
• Primary Examiner(s): Croyle, Carlton R.
• Assistant Examiner(s): Stout, Donald E.
• Application Number:
  US06/617,486
• Time in Patent Office: 952 Days
• Field of Search: 417/417, 417/416, 417/505, 417/486, 417/487, 417/444, 417/445, 310/32, 310/30, 310/28, 310/89, 310/104, 128/DIG. 12, 604/123, 604/152
• US Class Current: 417/417
• CPC Class Codes: A61M 5/14216 Reciprocating piston type
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: F04B 17/042 the solenoid motor being separated from the fluid flow
• CPC Class Codes: F04B 3/00 Machines or pumps with pistons coacting within one cylinder, e.g. multi-stage
• CPC Class Codes: F04B 53/008 Spacing or clearance between cylinder and piston

Abstract

An electromagnetic pump comprising a housing having a fluid receiving chamber in communication with an inlet, a pair of fluid chambers connected by a fluid bypass passage to accommodate bubbles, one in communication with the fluid receiving chamber and the other in communication with an outlet, an electromagnet carried by the housing located external to the fluid chambers thereof, and a barrier in the form of a thin diaphragm of fluid impermeable material which hermetically isolates the electromagnet from the fluid chambers. An armature in the housing is movable within a body of magnetically permeable material which contains the bypass, has a pole portion located for magnetic attraction by the electromagnet, and has a piston portion, preferably of smaller cross-section than the pole portion, for forcing fluid from the fluid chambers and through the outlet. The armature is moved from a rest position through a forward pumping stroke when attracted by the electromagnet and is moved by a biasing spring in an opposite direction through a return stroke back to the rest position. A main valve is movably carried by the armature and located in the fluid receiving chamber for closing the pump inlet when the armature is in the rest position and allowing opening the inlet after the armature begins the forward pumping stroke. The structure and arrangement of the check valve minimizes the volume of the fluid receiving chamber to limit the maximum size of a bubble contained therein. A bypass passage containing a check valve which opens during the armature return stroke provides a path for bubbles around the piston to the fluid receiving chamber.

Claims

1. An electromagnetic pump comprising:

(a) an elongated housing having a longitudinal axis and 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 for movement along said housing longitudinal axis and 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;

(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 electromagnet means;

(f) said check valve means comprising a thin body movably carried by said armature and located in said interior fluid containing region in small clearance relation therewith and between said armature and said inlet, and a conical spring between said valve body and said armature thereby enabling said pump chamber to have dimensions which define a volume not greater than about one and one-half times the stroke volume of the pump which therefore limits the volume of a bubble in the fluid which can be contained in said pump chamber up to a volume of about one and one-half times the stroke volume the pump when said armature is in a rest position so as to enable said pump to operate with bubbles present in the fluid being pumped;

(g) said armature pole portion having a pole face located to define said gap with said electromagnet means; and

(h) said fluid-containing region of said housing and said electromagnet means being in axially spaced relation along said housing longitudinal axis and being separated by barrier means of fluid impervious material having opposite sides, said fluid containing region, inlet, outlet and armature all being located on one side of said barrier means and said electromagnet means being located on the opposite side of said barrier means.

2. A pump according to claim 1, wherein said check valve means is operatively coupled to said armature and located in said fluid receiving chamber for opening and closing said inlet, said check valve means having a structure, size and relatively close clearance with said chamber so as to determine the volume of said fluid-receiving chamber and thereby limit the size of a bubble which can be contained in said chamber.

3. A pump according to claim 2, wherein said armature has an end face disposed in a plane substantially perpendicular to the direction of movement of said armature and located in said fluid-receiving chamber and facing said inlet, and wherein said check valve means is movably carried by said armature on said end face and comprises:

(a) a valve body; and

(b) biasing means between said valve body and said armature end face for moving said body into a position closing said inlet.

4. A pump according to claim:

3, wherein said valve body is of elastomer material in the form of a disc having a planar surface thereof facing said inlet for closing the same, said disc having a diameter selected to provide a relatively close, movable and loose fit in said fluid receiving chamber and said disc being relatively thin.

5. A pump according to claim 3, wherein said biasing means comprises a conical spring having one end operatively contacting said valve body and having the opposite end contacting said armature end face.

6. A pump according to claim 1, wherein said armature piston portion is located between a plunger portion and said pump inlet and movable within said pump housing, there being a relatively small clearance between said armature piston portion and said housing, said armature piston portion including two axially adjacent sections of different cross-section, one of said sections being axially near said plunger portion and of smaller cross-section than the other of said sections, the clearance between said one section and said housing being slightly larger than the clearance between said other section and said housing thereby serving to prevent entry of bubbles into the clearance between said other section and said housing.

7. A pump according to claim 1, wherein said armature pole portion has a pole face of relatively large area disposed in a plane substantially perpendicular to the direction of movement of said armature.

19. A pump according to claim 1, wherein said path providing means comprises:

(a) passage means in said housing for placing said fluid pumping chamber and said fluid receiving chamber in fluid communication; and

(b) check valve means in said passage means movably closed during said forward pumping stroke of said armature and normally open during said return stroke of said armature.

20. A pump according to claim 19, wherein said passage means comprises a first passage leading from said fluid pumping chamber in a direction generally parallel to the direction of movement of said armature, a second passage leading from said first passage to said fluid receiving chamber, and means defining a valve seat at the junction between said first and second passages, and wherein said check valve means comprises a valve body positioned for movement in said first passage and having a surface adapted to contact said valve seat and biasing means operatively contacting said valve body and a surface of said first passage, said biasing means normally urging said valve body into contact with said valve seat to block fluid communication between said first and second passages and operable to allow movement of said valve body away from said valve seat to place said first and second passages in fluid communication.

8. An electromagnetic pump comprising:

(a) an elongated housing having a longitudinal axis and having an interior fluid containing region including a fluid receiving chamber, a first fluid chamber in fluid communication therewith, a second fluid chamber in fluid communication with said first fluid chamber, an inlet in fluid communication with said receiving chamber and an outlet in fluid communication with said second fluid chamber;

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

(c) an armature positioned in said fluid containing region of said housing for movement along said housing longituginal axis and having a pole portion located for magnetic attraction by said electromgnet means and having a piston portion operatively associated with said fluid receiving and said first fluid chambers for forcing fluid from said fluid receiving chamber through said first and second chambers and out 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 chambers through said outlet and for movement in an opposite direction through a return stroke back to said rest position;

(d) means for 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 electromagnet means;

(e) check valve means operatively coupled to said armature and located in said fluid containing region of said housing for closing said inlet when said armature is in said rest position and for opening said inlet after said armature begins movement associated with said forward pumping stroke, said check valve means 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;

(f) said armature piston portion being located between a plunger portion and said pump inlet and movable within said pump housing, there being a relatively small clearance between said armature piston portion and said housing, said armature piston portion including two axially adjacent sections of different cross-section, one of said sections being axially near said plunger portion and of smaller cross-section than the other of said sections, the clearance between said one section and said housing being slightly larger than the clearance between said other section and said housing and thereby serving to prevent entry of bubbles into the clearance between said other section and said housing;

(g) said armature pole portion having a pole face located to define said gap with said electromagnet means; and

(h) said fluid-containing region of said housing and said electromagnet means being in axially spaced relation along said housing longitudinal axis and being separated by barrier means of fluid impervious material.

9. A pump according to claim 8, further including a body in said housing fluid containing region between said first and second fluid chamber, said body having a passage therethrough for receiving said armature pole portion in a movable, relatively close fitting relation and further including:

means for providing a bypass passage in said body in direct communication with said first and second fluid chambers to allow bubbles in the fluid to pass said body and said armature pole portion with little pressure drop.

10. A pump according to claim 9, wherein said armature piston portion is located between a plunger portion and said pump inlet, said piston portion having a cross-sectional size smaller than the cross-sectional size of said armature pole portion.

11. A pump according to claim 8, wherein said check valve means is located in said fluid receiving chamber for opening and closing said inlet, said check valve means having a structure, size and relatively close clearance with said chamber so as to determine the volume of said fluid-receiving chamber and thereby limit the maximum size of a bubble which can be contained in said chamber.

12. A pump according to claim 11, wherein said armature has an end face disposed in a plane substantially perpendicular to the direction of movement of said armature and located in said fluid-receiving chamber and facing said inlet, and wherein said check valve means is movably carried by said armature on said end face and comprises:

(a) a valve body; and

(b) biasing means between said valve body and said armature end face for moving said body into a position closing said inlet.

13. A pump according to claim 12, wherein said valve body is of elastomer material in the form of a relatively thin disc having a planar surface thereof facing said inlet for closing the same, said disc having a diameter selected to provide a relatively close, movable and loose fit in said fluid receiving chamber, and wherein said biasing means comprises a conical spring having one end operatively contacting said valve body and having the opposite end contacting said armature end face.

14. A pump according to claim 8, wherein said armature piston portion is 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, and further including;

means for providing a bypass path for bubbles in the fluid around said armature piston portion between said first fluid chamber and said fluid receiving chamber.

15. A pump according to claim 14, wherein said path providing means comprises:

(a) passage means in said housing for placing said first fluid chamber and said fluid receiving chamber in fluid communication; and

(b) check valve means in said passage means normally closed during said forward pumping stroke of said armature and normally open during said return stroke of said armature.

16. A pump according to claim 8, said barrier means having opposite sides, said fluid containing region, inlet, outlet and armature all being located on one side of said barrier means and said electromagnet means being located on the opposite side of said barrier means.

17. A pump according to claim 8, wherein said armature pole portion has a pole face of relatively large area disposed in a plane substantially perpendicular to the direction of movement of said armature.

18. 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 though 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 meand for moving said armature toward said electromagnet means to close said gap in response to electrical energization of said electromagnet means; and

(f) 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.