Low power electromagnetic pump

• US 4,568,250 A
• Filed: 05/23/1983
• Issued: 02/04/1986
• Est. Priority Date: 09/07/1982
• Status: Expired due to Term

• Current Assignee: GREATBATCH WNRWEPEIAWA, INX., 10,000 WHERLE DR., CLARENCE, NY 14031
• Original Assignee: Greatbatch Enterprises, Inc.
• Inventors: Falk, Theodore J., Morris, Lawrence E.
• Primary Examiner(s): Husar, Cornelius J.
• Assistant Examiner(s): Cuomo, Peter M.
• Application Number:
  US06/496,822
• Time in Patent Office: 988 Days
• Field of Search: 417/417, 417/416, 417/DIG. 1, 417/505, 417/486, 417/487, 417/444, 417/445, 417/244, 417/254, 417/257, 417/240, 417/241
• US Class Current: 417/254
• 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 serially-connected fluid pumping chambers, 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 heremetically isolates the electromagnet from the fluid chambers. An armature in the housing is movable within a body of magnetically permeable material, has a pole portion located for magnetic attraction by the electromagnet, and has first and second plunger portions in respective ones of the pumping chambers for forcing fluid out of the chambers and through the outlet. The armature is moved from a rest position through a forward pumping stroke when attracted by the electromagnet to force fluid from one pumping chamber to the other and then out of that chamber through the outlet, and the armature is moved by a biasing spring in an opposite direction through a return stroke back to the rest position. A pump check valve is within the pump and associated with the armature in the form of a valve member located in the fluid receiving chamber, movably carried by the armature, and positioned for closing the pump inlet when the armature is in the rest position and opening the inlet after the armature begins the forward pumping stroke. The arrangement is such that the volume of the fluid receiving chamber is minimized in the region between the check valve and the neighboring one of the armature plunger portions. Long term sealing against back flow is provided by a relatively stronger biasing spring, and short term sealing by a relatively weaker biasing spring.

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, a first fluid pumping chamber in fluid communication therewith, a second fluid pumping chamber in fluid communication with said first pumping chamber, an inlet fluid communication with said receiving chamber and an outlet in fluid communication with said second pumping 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 longitudinal axis and having a pole portion located for magnetic attraction by said electromagnet means and having a first plunger portion in said first pumping chamber for forcing fluid out of said first chamber into said second chamber and a second plunger portion in said second pumping chamber for forcing fluid out of said second 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 pumping 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 receiving chamber 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 second armature plunger portion having a pole face disposed in a plane substantially perpendicular to the direction of movement of said armature, said pole face being located to define said gap with said electromagnet means, said pole face being of relatively large area; and

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

2. A pump according to claim 1, wherein said check valve means is in relatively close-fitting relation to the portion of said housing defining said fluid receiving chamber, said check valve means is closely coupled to and located closely adjacent said armature, and the portion of said armature adjacent said check valve means is in relatively close-fitting relation to said housing thereby decreasing the volume of said interior fluid containing region between said armature and said check valve means.

3. A pump according to claim 2, wherein the cross-sectional dimension of said armature portion adjacent said check valve means and the cross-sectional size of the associated portion of said housing are so related to define a close tolerance space therebetween serving as a leakage path for fluid from said first pumping chamber to said receiving chamber during movement of said armature through said return stroke.

4. A pump according to claim 1, wherein said housing includes a cylindrical portion adjacent said inlet and having a first inner diameter section containing said check valve means in relatively close-fitting relation and a second, smaller inner diameter section containing said first plunger portion of said armature in relatively close-fitting relation, said check valve means being closely coupled to and located closely adjacent said armature, thereby decreasing the volume of said interior fluid containing region between said armature and said check valve means.

5. A pump according to claim 4, wherein the inner diameter of said second housing section and the outer diameter of said armature first plunger portion are so related to define a close tolerance space therebetween serving as a leakage path for fluid from said first pumping chamber to said receiving chamber during movement of said return stroke.

6. A pump according to claim 1, further including a body of magnetically permeable material in said housing fluid containing region between said first and second fluid pumping chambers, said body defining a portion of said magnetic circuit, said body having a passage therethrough for receiving said second armature plunger portion in a movable, relatively close-fitting relation whereby said armature moves in said body during said forward and return strokes and said magnetic circuit is through said body and said second armature plunger portion.

7. A pump according to claim 6, further including a protective coating on the outer surface of said second armature plunger portion which moves in said passage.

8. A pump according to claim 7, wherein said protective coating is of fluoropolymer material.

9. A pump according to claim 1, further including biasing means in said housing for urging said armature toward said rest position.

10. A pump according to claim 1, further including:

(a) first biasing means for urging said armature toward said rest position;

(b) second biasing means for urging said check valve means toward a position closing said inlet; and

(c) the force provided by said first biasing means being greater than the force provided by said second biasing means.

11. A pump according to claim 1, wherein said inlet is located at one end of said housing, and said check valve means is located at one end of said armature disposed toward said inlet.

12. A pump according to claim 11, wherein said inlet comprises a passage terminating in an annular valve seat facing said check valve means and wherein said check valve means has a surface moved into and out of contact with said valve seat for closing and opening said inlet.

13. A pump according to claim 1, further including

(a) first biasing means operatively associated with said armature for providing long term sealing of said pump inlet;

(b) second biasing means operatively associated with said check valve means for providing short term sealing of said pump inlet; and

(c) the force provided by said second biasing means being weaker than the force provided by said first biasing means;

(d) whereby sealing against back flow is provided when said pump is not in operation while pressure drop across said check valve means is relatively small during the pumping stroke.

14. A pump according to claim 1, wherein said barrier means is disposed in a plane substantially perpendicular to said housing longitudinal axis.

15. An electromagnetic pump comprising:

(a) a housing having an interior fluid containing region including a fluid receiving chamber, a first fluid pumping chamber in fluid communication therewith, a second fluid pumping chamber in fluid communication with said first pumping chamber, an inlet in fluid communication with said receiving chamber and an outlet in fluid communication with said second pumping 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 having a pole portion located for magnetic attraction by said electromagnet means and having a first plunger portion in said first pumping chamber for forcing fluid out of said first chamber into said second chamber and a second plunger portion in said second pumping chamber for forcing fluid out of said second 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 pumping 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 receiving chamber 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 check valve means being in relatively close-fitting relation to the portion of said housing defining said fluid receiving chamber, said check valve means being closely coupled to and located closely adjacent said armature, and the portion of said armature adjacent said check valve means being in relatively close-fitting relation to said housing thereby decreasing the volume of said interior fluid containing region between said armature and said check valve means;

(g) first biasing means operatively engaging said first plunger portion of said armature for urging said armature toward said rest position and providing long term sealing of said pump inlet;

(h) second biasing means operatively engaging said first plunger portion of said armature and said check valve means for urging said check valve means toward a position closing said inlet and providing short term sealing of said pump inlet;

(i) the force of said first biasing means being transferred to said check valve means when said armature is in said rest position; and

(j) the force provided by said second biasing means being weaker than the force provided by said first biasing means;

(k) whereby sealing against back flow is provided when said pump is not in operation while pressure drop across said check valve means is relatively small during the pumping stroke.

16. A pump according to claim 15, wherein the cross-sectional dimension of said armature portion adjacent said check valve means and the cross-sectional size of the associated portion of said housing are so related to define a close tolerance space therebetween serving as a leakage path for fluid from said first pumping chamber to said receiving chamber during movement of said armature through said return stroke.