CA1117367A

CA1117367A - Dual action solenoid pump

Info

Publication number: CA1117367A
Application number: CA000315079A
Authority: CA
Inventors: Francis W. Child
Original assignee: Child Laboratories Inc
Current assignee: Child Laboratories Inc
Priority date: 1978-03-20
Filing date: 1978-10-31
Publication date: 1982-02-02
Also published as: US4221548A

Abstract

ABSTRACT OF THE DISCLOSURE:
A pump for moving a fluid, as blood, having a body and end members forming a cylindrical chamber. A free floating piston located in the chamber is moved along the length of the chamber with a solenoid to pump blood into and out of opposite ends of the chamber. The end members containing inlet and outlet valves and sleeves are adapted to attach to veins or tubes to carry the blood to and from the pump.
When electrical power is applied to the solenoid, a magnetic force operates o move the piston in the chamber, thereby pumping blood into and out of the chamber through the valves in the opposite end members.

Description

J~ $

SUMMAR~r OF INVFNTION:
.. . . .
The invention is directed to a pump for moving a fluid, as blood. The pump is a double-acting pumping apparatus that has a body having a cylindrical chamber. A piston moves in the chamber to move the fluid into and out of the opposite ends of the chamber. A solenoid surrounding the body is operable to drive the piston between the opposite ends of the chamber. End members mounted on opposite ends of the body have inlet and outlet passages for carrying the fluid into and out of the opposite ends of the chamber. One-way valves located in the passages control the flow of -fluid into and out of the opposite ends of the chamber. When elec-tric power is applied to the solenoid, magnetic force func-tions to reciprocate the piston in the chamber to ef~ect pump-ing of the fluid.
The pump is operable to move blood in a manner that simulates the pumping action of a natural heart. The , ...
blood containing chamber is divided by the movable piston so that the pump simulates two chambers of the heart.
, . ..
`~ 20 The piston is enclosed within the blood chamber so that it does not allow any contamination of the blood, nor the leak- ~-` age of the blood from the chamber. The controls for the ; solenoid are operable to automatically control the magnetic force applied to the piston and thereby control the pumping rate and pressure of the blood in the chamber.
, , IN THE DRAWINGS:
Figure 1 is a plan view of the pump of the invention;
Figure 2 is an end elevational view of the left end of Figure l;
Figure 3 is an enlarged sectional view taken along the line 3-3 of Figure 2;

, . ~

Figure 4 is a sectional view taken along the line 4-4 of F:igure 3;
Figure 5 is a plan view of a modification of the pump of the invention;
Figure 6 is an end elevational view of the left end of Figure 5;
Figure 7 is an enlarged sectional view taken along the line 7-7 of Figure 6; and Figure 8 is a sectional view taken along the line 8-8 of Figure 7.
DESCRIPTION OF PREFERRED EMBODIMENTS:
Referring to the drawings, there is shown in Figure 1 the fluid pump of the invention indicated generally at 10. Pump 10 is a dual or double-acting pump operable to move fluid in two pulses per cycle of movement of the pump piston. The pump ;
;....... . is operable to move fluids, as water, oil, and biological fluids, such as blood. The pump hereinafter described will be described as a blood pump.
Pump 10 has a cylindrical body 11 surrounding a cylindri-cal chamber 12. A free floating valving member or disc piston13 is located in chamber 12. Piston 13 is movable in response `~- to electro-magnetic force to pump blood into and out of the ., ;
opposite ends of chamber 12.
A first end assembly indicated generally at 14 is mounted on the left end of body 11. End assembly 14 has one-way inlet . ~ . .
~ and outlet valves for controlling the flow of blood into and: ,:
out of the left section 12A of chamber 12. The opposite end of body 11 carries the second end assembly indicated generally .
~ at 16. End assembly 16 also has one-way inlet and outlet ; `~ 30 valves for controlling the flow of blood into and out of the ` right section 12B of chamber 12. A solenoid having a coil or ~3~

' . ~,', '.., ' .

: ~,.:

~inding 21 located around wall 17 extends from flange 18 to end flange 19. The number of turns oE the coil is selected to provide for the optimum flux densities and pumping pres-sures in the chambcr 12. Walls 16 and 17 and casing 22 are made of materials that are biologically inert and compatible with the body tissues, including the blood. ~all 17 and cas-ing 22 can be coated with a layer of Pyrolite ~registered trade mark) carbon as disclosed in U.S. Patent 3,835,475.
Piston 13, as shown in Figures 3 and 4, is a generally flat disc-like member having a circular substrate or core 23 of graphite, plastic or other lightweight material. A
ring 24 of magnetic material, such as iron, or a cobalt iron alloy, is imbedded in the outer peripheral portion of core 23.
Core 23 is covered with an outer skin or coating 26 of hard, wear-resistant and biologically inert material, such as Pyrolite ; carbon. The material can be a silicon alloy Pyrolite carbon, as disclosed in U.S. Patents Nos. 3,54~,711 and 3,835,475.
As shown in Figure 3, piston 13 has flat outside surfaces 13A and 13B extended generaIly transverse to the longitudinal axis of the chamber 12. The surfaces 13A and 13B join with a cylindrical outer peripheral surface 13C.
Wall 17 has a plurality of longitudinal lands or ribs 20. Ribs 20 are circumferentially spaced from each other and extend the entire length of wall 17~ The opposite ends of ribs 20 are enlarged and form stop members 20A and 20s that are engaged by piston 13 to limit the opposite longi-; tudinal movements of piston 13. Ribs 20 locate the outer cylindrical surface 13C of piston 13 a short distance inwardly from the wall 17. This provides separate arcuate spaces or passages 27 between chamber sections 12A and 12B. Passages 27 allow a slight flow or leakage of blood past piston 13 to - 4 ~

keep the blood moving in annular space 27 and chamber sections 12A and 12B, thereby avoiding clotting and damage to the blood tissue.
As shown in Figures 3 and 4, four separate arcuate passages 27 are spaced circumferentially around the piston 13. This insures that there is a slight flow of blood past the entire , outer peripheral surface 13C of the piston. The piston 13 can rotate about its longitudinal axis as it reciprocates between stop members 20A and 20B.
End assembly 14 has a circular end member 28 attached to flange 18 and casing 22. The outer peripheral edge of member 28 has an outwardly open annular groove 29 receiving an in-wardly turned lip 31 integral with the outer end of flange 18.
Lip 31 holds the member 28 in fixed assembled relation with flange 18. Casing 22 has an inwardly turned end 32 that is curved down over the portion of end member 28.
A pair of outwardly directed tubular extensions or nipples ;
33 and 34 are adjoined to the center portion of end member 28.
Nipple 33 has an inlet passage 36 leading to the chamber section lZA. A one-way valve unit 37 is located in passage 36. Valve unit 37 has pivot members 38 and 39. A pivoting ~ :
~: disc or v~lving element 41 is operatively carried by pivot members 38 and 39. Disc 41 functions to permit the flow of blood into chamber 12A and restricts the flow of blood out of chamber 12A. Pivot members 38 and 39 and disc 41 can be constructed in accordance with the heart valve disclosed in U. S. Patent No. 3,835,475. Other types of one-way valves, as ball valves and double leaflet valves, can be used to control the flow of blood through nipple passage 36.
Nipple 34 has an outlet passage 42 in communication with the chamber section 12A. A one-way valve unit 43 is located , . ~

: . . ' . :

.

in passage 42 to control the flow of blood out through passage 42. Valve unit 43 has pivot members 44 and 45 carrying a pivoted disc or valving member 46. Disc 46 is operatively associated with pivot members 44 and 45 in a manner to permit the flow of blood out of the chamber section 12A through pass-age 42 and restrict reverse flow from passage 42 back into chamber section 12A. Valving unit 43 can be constructed in accordance with the heart valve disclosed in U. S. Patent No.
3,834,475. Other types of one-way valves can be used with nipple 34 to control the outlet flow of blood from the chamber section 12A. Other examples of suitable one-way valves are shown in U. S. Patents Nos. 3,130,419; 3,4169159; 3,476,143;
; 3,632,212 and 3,824,729.
End assembly 16 has a circular end member 48 provided with an outwardly open annular groove 49. An inwardly turned lip integral with the flange 19 is turned over into the groove 49 to secure the end member to flange 19. Casing 22 has an ; end that is turned down over the end member 28, thereby attaching the casing to the end member. Other types of structures can be used to connect the wall 17 and casing 22 to the end members 14 and 16, respectively.
End member 48 has a pair of tubular extensions or nipples 53 and 54 adapted to be connected to veins or tubing with suit-able attaching structures, such as sutures. Nipple 53 has an inlet passage 56. A one-way inlet valve unit 57 is located in passage 56. Valve unit 57 is operable so as to allow blood to flow into the chamber section 12B and restrict the reverse or outflow of blood from the chamber section 12B. Nipple 54 has an outlet passage 58 in communication with the chamber section 12B. A one-way outlet valve unit 59 is located in the inlet end of passage 58. Valve unit 59 allows the flow of :. I , . -,:

blood out of chamber section 12B and restricts the reverse or inflow of blood from passage 58 to chamber 12B. Valve units 57 and 59 follow the construction of the valve units 37 and 43.
A control circuit 61 is connected to the solenoid coil 21 with suitable leads 62. A power source 63 is coupled to control unit 61. The power source 63 can be rechargeable batteries or an outside power sourceO Control 61 is operable to reverse the -flow of electric current through the solenoid coil 21 and thereby establishes sequential reverse flux fields or magnetic force which acts on iron ring 24 to move the piston 13 in opposite directions, as indicated by the arrow 64. Con-trol 61 can be responsive to variations of both the inlet and outlet blood pressures to operate solenoid 21 in a manner which maintains the blood pressure within a normal natural range.
In use, the flux field established by solenoid coil 21 sequentially moves piston 13 from one end of chamber 12 to the opposite end of chamber 12. When piston 13 moves to the right, as shown in Figure 3, the blood will flow through inlet pass-age 36 into the chamber section 12A. Valve unit 43 will be closed, thereby restricting the flow of blood from passage 42 into chamber 12A. Movement of the piston 13 to the right also causes the blood in the chamber section 12B to flow through the ~;
outlet valve 59 into the outlet passage 58. Valve unit 57 is closed, thereby restricting the flow of blood into passage 56. `
The blood is pumped out of chamber section 12B and is drawn ; into chamber section 12A. When the piston 13 reaches stops 20A, the electric power to the solenoid coil 21 is reversed.
This applies a reverse flux force on iron ring 24 moving the i piston to the left into engagement with stops 20B. The blood in chamber section 12A will flow out through valve unit 43 and passage 42. Valve unit 37 is closed, thereby restricting the flow of blood through passage 36. Valve unit 57 will openallowing the blood to flow to passage 56 into chamber section 12B. Valve unit 59 closes to restrict the reverse flow of blood through passage 58 into chamber section 12B. The con-trol 61 regulates the timing or se~uence cycle of the piston 13 so that the blood is pumped according to the normal heart functions of a natural heart. ~-Referring to Figure 5, there is shown a modification of the fluid pump, such as a blood pump, indicated generally at 100. Pump 100 has an elongated cylindrical body 111 surround-ing a cylindrical pumping chamber 112. Pumping chamber 112 is divided into ~wo separate chambers 112A and 112B with a re-ciprocating valving member or piston indicated generally at 113. Piston 113 is a cylindrical disc-like member that is slid-ably located in chamber 112 for reciprocating movement to oppo-site ends of chamber 112. End assemblies 114 and 116 are attached to opposite ends of the body 111 to complete the pump.
Body 111 has a cylindrical sleeve 117 surrounding chamber 112. A plurality of inwardly projected annular ribs or lands .' . .
118 are circumferentially spaced around sleeve 117. Ribs 118 ~ -; *erminate at their opposite ends in end stop members or pro- ~ ;
jections ll9 and 121. End stop members 119 and 121 cooperate `
with piston 113 to fix the end or terminal locations of piston 113 at the opposite ends of chamber 112. Piston 113 divides the chamber 112 into a first or left chamber 112A and a second or right chamber 112B.
Referring to Figure 7, piston 113 has a core 122 carrying a ferromagnetic metal ring 123. Ring 123 is a cylindrical member and can be made of iron, cobalt-iron alloy, and like 30 materials. A skin or outer layer 124 surrounds core 122 and ~ ,o /;~ ~
ring 123. Skin 124 can be a ~ carbon material. Other .
. ~ .

3~ ~

types of skin or coating materials can be applied to the core and ring. Piston 113 has a genera]ly cylindrical outer surface or wall 126 that engages the outer edges of ribs 118. Surface 126 is spaced from the inside surface of annular sleeve 117 by a plurality of spaces or arcuate passages 127 which allow the blood to flow around piston 113 as it moves in chamber 112. Piston 113 reciprocates between the opposite ends of chamber 112 and rotates about its longitudinal axis, thereby providing the piston with a minimum of wear as it slides on ;
the outer edges of ribs 118. A limited amount of blood moving through spaces 127 between adjacent ribs 118 washes the outer surface of the piston 113 and wall 117 and also provides lubri-cation for piston 113.
End assembly 114 has a circular plate or housing 128 located in engagement with the left end of annular sleeve 117. ~lousing 128 has a central opening 129 in communication with chamber 112A. An inlet nipple 131 projects outwardly Erom plate 128 and has an inlet passage 133. A second or outlet nipple 132 projects out~ardly from plate 128 and has an outlet passage 134. Passages 133 and 134 are in communi-cation with the opening or vestibule chamber 129.
A one-way valve unit indicated generally at 136 is located in passage 133. Valve unit 136 allows the -Elow of blood into opening 129 and chamber 112A. When valve unit 136 is in its closed position, it restricts the reverse flow of blood through passage 133. Valve unit 136 comprises a circular disc 137 located in passage 133. Two pairs of pivots or pivot members 138 and 139 pivotally mount the disc on the nipple 131 for movement about offset from the center of the disc allowing the disc to pivot between its open and closed ; position, as shown in solid and broken lines.

A second one-way valve unit 137 is interposed in the passage 134 to control the flow of fluid out of the chamber 112A. When valve unit 141 is in the closed position, it :
restricts the reverse flow or inlet flow of fluid through passage 134 into the chamber 112A. Valve unit 141 comprises a circular disc 142 that is pivotally mounted on two pairs `~
of pivot members 143 and 144. The pivot members 143 and 144 - `~
are operative to control the off center pivotal movement of the disc 142 between its open and closed positions while it :
10 retains the disc in its operative relationship with the inside ~;
walls of the nipple 132.
An end assembly 116 is identical with end assembly 114. -::.
Assembly 116 has a plate or housing 146 surrounding an opening ~:
or vestibule chamber 147. Opening 147 is in communication with the right end o chamber 112B. Housing 114 includes an inlet nipple 148 and an outlet nipple 149. Inlet nipple 148 has an inlet passage lSl accommodating a one-way valve unit indicated generally at 153. Outlet nipple 149 has an : .
outlet passage 153 accommodating a one-way valve unit indicated generally at 158. Inlet and outlet passages 151 and 152 are in communication with the vestibule chamber 129.
One-way valve unit 153 includes a pivoting disc 154 that is mounted for off-center pivotal movement on pairs of pivot members 156 and 157. Valve unit 153 functions to allow the blood to flow into passage 151 into the opening 147 and chamber 112B and restrict reverse flow of blood through passage 151.
One-way valve unit 158 has a disc 159 that is pivoted : .
off center on a pair of pivot members 161 and 162. Valve unit 158 allows blood to flow out of chamber 112B and restricts the reverse flow or inflow o blood into the chamber 112B.

. "

.,. - . . . , ;~ . . .
.'. ' ' ' ... . ... .,,. , - ~ , , : : ., :

Other types o-f one-way valves, as ball valves and double leaf-let valves, can be used to control the flow of blood through passages 133, 134, 151 and 152. Examples of suitable one-way valves are shown in U. S. Patent No. 3,835,475.
A first winding or solenoid coil 163 is wound around the left half of sleeve 117. A second winding or solenoid coil 164 is wound around the right half of sleeve 117. An annular ring 166 is interposed between the adjacent ends of the sole-noids 163 and 164. A pair of cover sleeves 167 and 168 surround the solenoids 163 and 164, respectively. Ring 166 has a pair of grooves 169 that accommodate the ends of the sleeves 167 and 168. Similar grooves are on the inside sur- ~-faces of plates 128 and 146, respectively, to accommodate the opposite or outer ends of the sleeves 167 and 168.
Referring to Figure 5, an electrical control 174 is used ~ -to selectively energize solenoid coils 163 and 164. Control 174 is coupled to a power source 176, such as a battery or an outside source of power. Conductor lines 177 connect control 174 to solenoid 163. Conductor lines 178 connect the control 174 with solenoid 164. The control 174 is operable to control the cycling freque~cy of the solenoids 163 and 164 and the amount of current supplied to the solenoids.
In use, the solenoids 163 and 164, when energized, establish sequential reverse magnetic forces that reciprocate piston 113 in chamber 112. The energization of solenoid 163 will move the piston 113 to the left, thereby forcing the blood in chamber 112A through the outlet opening 134. One-way valve 136 will remain closed, whereby the blood opens the one-way valve 141.
When the solenoid 164 is energized, piston 113 moves to the right, thereby moving the blood in chamber 112~ out through the passage 152. One-way valve 158 will open. The ' ' ' '- ~

. , inlet one-way valve 153 will close. During the movement of piston 113 to the right, blood will flow through passage 133 as the one-way valve 136 is open into chamber 112. The piston 113, being enlarged on the left side, fills in part of the chamber 112A so that a smaller quantity of blood is pumped from chamber 112A than is pumped from the larger chamber 112B. Piston 113 can be symmetrically balanced, such as the piston 113 shown in Figure 3. This will provide for an equal amount of pumping of blood from each of the -chambers on the opposite sides of piston 113.
While there have been shown and described the preferred embodiments of the invention, it is understood that changes ~`
in the structure, size, valves, pistons, solenoids, and con-trols for the solenoids can be made by those skilled in the art without departing from the invention. The invention is defined in the following claims.

........ ~ "

2~

' ', '' ::

,~
~, . ':;

~.

; . , ., . , , " .. , , "
,:. ,, . -~
~ , ,- ;:
;, . .. ., . ;: .. . ::: : : -: , . - . . . .

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A pump for moving a fluid comprising:
a body having first and second ends and a chamber open to said ends, a first end member mounted on the first end of the body, a second end member mounted on the second end of the body, each of said end members having fluid inlet and fluid outlet passages, one-way inlet valve means in the inlet pass-ages to control the flow of fluid into the opposite ends of the chamber, one-way outlet valve means in the outlet passages to control the flow of fluid out of the opposite ends of the chamber, a piston located in the chamber, said piston being free to move in said chamber between the first and second end members, said piston including magnetic material, rib means cooperating with said body and piston to space the piston from said body to allow a limited amount of fluid to flow around the piston when the piston reciprocates in the chamber, sole-noid means for establishing sequential reverse magnetic force, and control means connected to the solenoid means to provide electric energy to energize the solenoid means whereby the sequential reverse magnetic force of the solenoid means act-ing on the magnetic material reciprocates the piston in the chamber, thereby moving fluid into and out of the opposite ends of the chamber through the inlet and outlet passages.

2. The pump of Claim 1 wherein: the body has an inside wall surrounding the chamber, said rib means compris-ing a plurality of longitudinal inwardly directed ribs on said wall engageable with the piston to space the piston from the wall.

3. The pump of Claim 2 wherein: the piston has a cylindrical outer surface located in a contiguous relationship with the ribs.

4. The pump of Claim 2 including: stop members on opposite ends of the ribs to limit the reciprocating move-ment of the piston in the chamber.

5. The pump of Claim 1 wherein: the rib means comprise a plurality of longitudinal ribs on the body projected into the chamber and engageable with the piston located in the chamber.

6. The pump of Claim 5 including: stop members asso-ciated with opposite ends of the ribs to limit the recipro-cating movement of the piston in the chamber.

7. The pump of Claim 1 wherein: the piston has a core, a ring of magnetic material associated with the outer portion of the core, and an outer skin covering the core and ring.

8. The pump of Claim 7 wherein: the outer skin is a Pyrolite carbon material.

9. The pump of Claim 1 wherein: the solenoid means extends the full length of the body, and a casing covers the solenoid means.

10. The pump of Claim 1 wherein: each end member has a chamber in communication with the body chamber.

11. The pump of Claim 1 wherein: each one-way inlet valve means and each one-way outlet valve means has a movable valving member.

12. The pump of Claim 11 wherein: the movable valving member is a pivoting disc.

13. The pump of Claim 1 wherein: each end member has a pair of tubular extensions having inlet and outlet passages leading to the chamber.

14. The pump of Claim 1 wherein: the solenoid means includes a pair of solenoids surrounding the body.

15. The pump of Claim 14 wherein: the pair of sole-noids includes a first solenoid surrounding one end of the body and a second solenoid surrounding the opposite end of the body.

16. The pump of Claim 1 wherein: the piston has a ring of magnetic material located adjacent one side of the piston.

17. A pump for moving a fluid comprising:
means having a chamber and inlet and outlet pass-ages in communication with opposite ends of the chamber, one-way inlet valve means operable to allow fliud to flow through the inlet passage into the opposite ends of the chamber and restrict flow of fluid out of the chamber, one-way outlet valve means operable to allow fluid to flow through inlet outlet passage out of the chamber and restrict flow of fluid into the chamber, a movable valving means located in the chamber, said valving means having magnetic material, rib means cooperating with said means having a chamber and movable valving means to space the valving means from said means having a chamber to allow a limited amount of fluid to flow around the valving means when the valving means moves in said chamber, solenoid means associated with means having a chamber for establishing sequential reverse magnetic force, and con-trol means connected to the solenoid means operable to pro-vide electric energy to energize the solenoid means whereby the sequential reverse magnetic force acting on the magnetic material of the valving means moves the valving means in a manner to move fluid into and out of the opposite ends of the chamber.

18. The pump of Claim 17 wherein: the means having a chamber includes a body having a cylindrical chamber.

19. The pump of Claim 17 wherein: the means having a chamber and an inlet and outlet passage including a body having a cylindrical chamber, first end means mounted on one end of the body, and second end means mounted on the opposite end of the body, each of said end means having an inlet pass-age and an outlet passage in communication with the associ-ated end of the chamber.

20. The pump of Claim 17 wherein: each one-way inlet valve means and each one-way outlet valve means has a movable valving member.

21. The pump of Claim 20 wherein: the movable valving member is a pivoting disc.

22. The pump of Claim 17 wherein: the movable valving means has a core, a ring of magnetic materials associated with the core, and an outer skin covering the core and ring.

23. The pump of Claim 22 wherein: the outer skin is a wear-resistant biologically inert material.

24. The pump of Claim 17 wherein: the movable valving means is a piston having a disc shape.

25. The pump of Claim 17 wherein: the means having a chamber includes an inside wall surrounding the chamber, said rib means comprising a plurality of longitudinally ex-tended ribs, said ribs extended into the chamber and engage-able with the valving means to space the valving means from said wall whereby a limited amount of fluid flows around the valving means when the valving means moves in the chamber.

26. The pump of Claim 25 including: stop members on opposite ends of the ribs to limit the reciprocating move-ment of the valving means in the chamber.

27. The pump of Claim 17 wherein: the solenoid means extends substantially the full length of the means having a chamber and include a casing for covering the solenoid means.

28. The pump of Claim 17 wherein: the solenoid means include a pair of solenoids surrounding the means having a chamber.

29. The pump of Claim 28 wherein: said pair of solenoids includes a first solenoid surrounding one end section of the means having a chamber and a second solenoid surrounding the opposite end section of the means having a chamber.

30. The pump of Claim 17 wherein: the valving means is a piston having a ring of magnetic material located adjacent one side of the piston.

31. A pump for moving fluid comprising: a body having a first end and a second end and a chamber opened to said ends, a first end member mounted on the first end of the body, a second end member mounted on the second end of the body, each of said end members having fluid inlet and fluid outlet pass-ages, one-way inlet valve means in the inlet passage to con-trol the flow of fluid into the opposite ends of the chamber, one-way outlet valve means in the outlet passages to control the flow of fluid out of the opposite ends of the chamber, a piston located in the chamber, said piston having a core, a ring of magnetic material associated with the outer portion of the core, and an outer skin covering the core and the ring, said piston being free to move in said chamber between the first and second end members, said piston including magnetic material, rib means cooperating with said body and piston to space the piston from said body to allow a limited amount of fluid to flow around the piston when the piston reciprocates in the chamber, solenoid means for establishing sequential reverse magnetic force, and control means connected to the solenoid means to provide electric energy to energize the solenoid means whereby the sequential reverse magnetic force of the solenoid means acting on the magnetic material reciprocates the pis-ton in the chamber thereby moving fluid into and out of the opposite ends of the chamber through the inlet and outlet pass-ages.

32. The pump of Claim 31 wherein: the outer skin is a Pyrolite carbon material.

33. The pump of Claim 31 wherein: the rib means comprise a plurality of longitudinal ribs projected into the chamber, said ribs being engageable with the outer skin of the piston.

34. The pump of Claim 33 including: stop members on oppo-site ends of the ribs to limit reciprocating movement of the piston in the chamber.

35. The pump of Claim 31 wherein: the ring of magnetic material is located adjacent one side of the piston.

36. The pump of Claim 31 wherein: each one-way inlet valve means and each one-way outlet valve means has a pivot-ing disc valving member.

37. The pump of Claim 31 wherein: the solenoid means in-cludes a pair of solenoids surrounding the body.

38. A pump for moving a fluid comprising: a body having first and second ends and a chamber open to said ends, said body having an inside wall surrounding the chamber, a first end member mounted on the first end of the body, a second end member mounted on the second end of the body, each of said end members having fluid inlet and fluid outlet passages, one-way inlet valve means in the inlet passages to control the flow of fluid into the opposite ends of the chamber, one-way outlet valve means in the outlet passages to control the flow of fluid out of the opposite ends of the chamber, a piston located in the chamber, said piston having a ring of magnetic material located adjacent one side of the piston, said piston being free to move in said chamber between the first and second end members, rib means on said inside wall spacing the piston from said inside wall whereby a limited amount of fluid flows around the piston when the piston moves in the chamber, solenoid means for establishing sequential reverse magnetic force, and control means connected to the solenoid means to provide electric energy to energize the solenoid means whereby the sequential reverse magnetic force of the solenoid means acting on the magnetic material reciprocates the piston in the chamber, thereby moving fluid into and out of the opposite ends of the chamber through the inlet and outlet passages.

39. The pump of Claim 38 including: an outer skin cover-ing the ring of magnetic material.

40. The pump of Claim 39 wherein: the outer skin is a Pyrolite carbon material.

41. The pump of Claim 38 including: ribs on said inside wall, and stop members on opposite ends of the ribs to limit reciprocating movement of the piston in the chamber.

42. The pump of Claim 38 wherein: the solenoid means in-cludes a pair of solenoids surrounding the body.

43. A pump for moving a fluid comprising: means having a chamber and inlet and outlet passages in communication with opposite ends of the chamber, said means including an inside wall surrounding the chamber, said wall having a plurality of longitudinally extended ribs, said ribs extended into the cham-ber, one-way inlet valve means operable to allow fluid to flow through the inlet passage into the opposite ends of the chamber and restrict the flow of fluid out of the chamber, one-way out-let valve means operable to allow fluid to flow through the outlet passage out of the chamber and restrict the flow of fluid into the chamber, a movable piston means located in the chamber, said piston means being engageable with the ribs to space the piston means from the wall whereby a limited amount of fluid flows around the piston means when the piston means moves in the chamber, said piston means having magnetic material, solenoid means associated with said means having a chamber for establishing sequential reverse magnetic force, and control means connected to the solenoid means operable to provide electric energy to energize the solenoid means whereby the sequential reverse magnetic force acting on the magnetic material of the piston means moves the piston means in a manner to move the fluid into and out of the opposite ends of the chamber.

44. The pump of Claim 43 wherein: the means having a chamber and an inlet and outlet passage including a body hav-ing a cylindrical chamber, first end means mounted on one end of the body, and second end means mounted on the opposite end of the body, each of said end means having an inlet passage and an outlet passage in communication with the associated end of the chamber.

45. The pump o-f Claim 43 wherein: each one-way inlet valve means and each one-way outlet valve means has a movable valving member.

46. The pump of Claim 45 wherein: the movable valving member is a pivoting disc.

47. The pump of Claim 45 wherein: the movable piston means has a core, a ring of magnetic material associated with the core, and an outer skin covering the core and ring.

48. The pump of Claim 47 wherein: the outer skin is a wear-resistant biologically inert material.

49. The pump of Claim 43 including: stop members on oppo-site ends of the ribs to limit the reciprocating movement of the valving means in the chamber.

50. The pump of Claim 43 wherein: the solenoid means in-clude a pair of solenoids surrounding the means having a cham-ber.

51. The pump of Claim 50 wherein: said pair of solenoids includes a first solenoid surrounding one end section of the means having a chamber and a second solenoid surrounding the opposite end section of the means having a chamber.

52. The pump of Claim 43 wherein: the magnetic material is a ring of magnetic material located adjacent one side of the piston means.

53. A method of pumping blood with the use of a body hav-ing a chamber and piston means located in said chamber compris-ing: separating the chamber into a first section and a second section with the piston means movably disposed in said chamber, reciprocating the piston means in said chamber with sequential reverse magnetic force to move blood into and out o-f said first and second sections of said chamber, allowing a limited amount of blood to flow around the piston means during move-ment thereof in said chamber, controlling the flow of blood into and out of the first section of the chamber in response to movement of the piston means in said chamber, and controlling the flow of blood into and out of the second section of the chamber in response to movement of the piston means in said chamber.

54. The method of Claim 53 wherein: the chamber has a longitudinal axis, and said piston means is reciprocated along said longitudinal axis, said flow of a limited amount of blood being a generally annular flow of blood around said piston means between said first and second sections of said chamber.

55. The method of Claim 54 including: allowing the piston means to rotate about said longitudinal axis simultaneously with the reciprocation of the piston means along said longi-tudinal axis.

56. The method of Claim 53 wherein: the piston means is moved in said chamber in one direction in response to a first magnetic force and moved in said chamber in the direction opposite the one direction in response to a second magnetic force.

57. The method of Claim 53 wherein: the piston means is reciprocated in said chamber with separate magnetic forces acting in opposite directions.

58. The method of Claim 53 wherein: said limited amount of blood flow moves through spaces provided by ribs separating a cylindrical wall of the body surrounding the chamber and the piston means.

59. The method of Claim 58 wherein: said piston means has a surface having a substantially constant radius of curvature engageable with said ribs to provide spaces between said sur-face and cylindrical wall for accommodating said limited flow of blood around the piston means.

60. The method of Claim 53 wherein: said body has a generally cylindrical wall surrounding said chamber, and said piston means has an outer peripheral surface located adjacent said cylindrical wall, said limited flow of blood past the piston means occurring around the piston means between the surface and the cylindrical wall whereby the blood moving past said piston means washes said surface and cylindrical wall.

61. The method of Claim 60 wherein: said cylindrical wall is separated from said outer peripheral surface with a plural-ity of ribs which provide arcuate spaces between said cylindri-cal wall and said outer peripheral surface, said limited flow of blood moving through said arcuate spaces.

62. The method of Claim 61 including: allowing the piston means to rotate about the longitudinal axis of the chamber as the piston means reciprocates in said chamber.

63. The method of Claim 53 wherein: the flow of blood into and out of the first chamber is controlled with first one-way inlet and outlet valves, and the flow of blood into and out of the second chamber is controlled with second one-way inlet and outlet valves.

64. An apparatus for pumping blood comprising: rigid means having a cylindrical wall surrounding a chamber, said means having an inlet port and an outlet port at each end thereof, check valve means associated with said inlet and out-let ports for controlling the flow of blood through said ports, and electric coils associated with said rigid means for creat-ing a magnetic field when current flows through said coils, piston means located within said chamber, said piston means being movable therein, said piston means having characteris-tics such that the piston means is attracted by the magnetic field resulting from the current flowing through the electric coils whereby the magnetic field moves the piston means in the chamber, said piston means having an outside diameter be-ing significantly less than the inside diameter of the cylin-drical chamber so as to foster at least some reverse flow of blood around said piston means during movement of the piston means in said chamber to promote the washing of the cylindri-cal wall and the piston means, and electrical means for pass-ing current alternately through said electric coils so as to cause the piston means to reciprocate between the ends of the chamber.

65. The apparatus of Claim 64 wherein: the electric coils are positioned circumferentially around the cylindrical wall.

66. The apparatus of Claim 64 including: rib means on said cylindrical wall engageable with said piston means to space said piston means from said wall.

67. The apparatus of Claim 66 wherein: said rib means comprise a plurality of ribs,each rib having a length extended longitudinally of said chamber.

68. The apparatus of Claim 64 wherein: said electric coils comprise a pair of coils positioned around separate por-tions of said cylindrical wall.

69. The apparatus of Claim 64 including: means located within said chamber and being adapted to engage said piston means to hold said piston means away from the wall of the chamber as the piston means reciprocates in said chamber.

70. The apparatus of Claim 69 wherein: said means mounted within said chamber comprise a plurality of longitudinal ribs fixed to the cylindrical wall.

71. The apparatus of Claim 64 wherein: said piston means has an outer surface having a substantially constant radius of curvature engageable with said rib to provide spaces be-tween said surface and said cylindrical wall for accommodating said limited flow of blood around the piston means.

72. An apparatus for pumping blood comprising: a body having an inside wall surrounding a chamber for accommodating blood, means having inlet and outlet passages in communication with opposite ends of the chamber, a plurality of longitudinally extended ribs on said wall, said ribs extended into the cham-ber, one-way inlet valve means operable to allow blood to flow through the inlet passages into the opposite ends of the chamber and restrict the flow of blood out of the opposite ends of the chamber, one-way outlet valve means operable to allow blood to flow through the outlet passages out of the opposite ends of the chamber and restrict the flow of blood into the opposite ends of the chamber, movable piston means located in the chamber, said piston means being engageable with the ribs to space the piston means from the wall whereby a limited amount of blood flows around the piston means when the piston means moves in the chamber, solenoid means associ-ated with said body for establishing sequential reverse magnetic force, and control means connected to the solenoid means oper-able to provide electric energy to energize the solenoid means whereby the sequential reverse magnetic force acting on the piston means moves the piston means in a manner to move blood into and out of the opposite ends of said chamber.

73. The apparatus of Claim 72 including: stop members on opposite ends of the ribs to limit the reciprocating move-ment of the piston means in the chamber.

74. The apparatus of Claim 72 wherein: the solenoid means includes a pair of solenoids surrounding the body.

75. The apparatus of Claim 74 wherein: said pair of solenoids includes a first solenoid surrounding one end sec-tion of the body and a second solenoid surrounding the opposite end section of the body.

76. The apparatus of Claim 72 wherein: said means having said inlet and outlet passages comprise first end means mounted on one end of the body and second end means mounted on the opposite end of the body, each of said end means having an inlet passage and an outlet passage in communication with an associated end of the chamber.

77. The apparatus of Claim 72 wherein: each one-way inlet valve means and each one-way outlet valve means has a movable valving member.

78. The apparatus of Claim 72 wherein: said piston means has an outer surface having a substantially constant radius of curvature engageable with said rib to provide spaces be-tween said surface and said cylindrical wall for accommodating said limited flow of blood around the piston means.