US 3791770 A
An electromagnetic pump or motor device includes a cylinder having a bore selectively sealed at its ends by removable valve plate assemblies communicating with a fluid system, a piston assembly movable in the bore of the cylinder, and spaced solenoid coils removably accurately positioned about the cylinder by a central radially outwardly projecting annular rib having two stop faces against which the inner ends of the coil housings abut, said solenoid coils being alternately energized to produce respective magnetic fields alternately for attracting the piston assembly to reciprocate the same in the bore. The piston assembly includes two spaced cylindrical pistons joined by a non-magnetic connecting pin or coupling, the piston assembly being of sufficient length to position a part of one piston radially inside the non-energized coil at the end of the piston assembly stroke, whereby such one piston is in a strong magnetic field for the return stroke of the cycle.
Claims available in
Description (OCR text may contain errors)
United States Patent 91 Farkos Feb. 12, 1974 Inventor: Robert A. Farkos, 63 York Rd., Hudson, Ohio 44236 Filed: May 24, 1973 Appl. No.: 363,332
U.S. Cl. 417/418 1  Int. Cl. F04b 17/04  Field of Search 417/50, 417, 418; 310/24  References Cited UNITED STATES PATENTS 2,515,110 7/1950 Bornstein 417/418 2,690,128 9/1954 Basilewsky... 417/418 2,988,264 6/1961 Reutter 417/418 3,103,603 9/1963 Reutter 417/418 3,134,938 5/1964 Morgan 417/418 3,282,219 11/1966 Blackwell et a1. 417/418 3,286,911 11/1966 Clarke 417/418 3,459,132 8/1969 Meyer 417/417 3,740,171 6/1973 Farkos 417/418 Primary Examiner-C. .l. l-lusar Attorney, Agent, or Firm-Donnelly, Maky, Renner & Otto [5 7] ABSTRACT An electromagnetic pump or motor device includes a cylinder having a bore selectively sealed at its ends by removable valve plate assemblies communicating with a fluid system, a piston assembly movable in the bore of the cylinder, and spaced solenoid coils removably accurately positioned about the cylinder by a central radially outwardly projecting annular rib having two stop faces against which the inner ends of the coil housings abut, said solenoid coils being alternately en- 9 Claims, 2 Drawing FEES ELECTROMAGNETIC PUMP OR MOTOR DEVICE WITH AXIALLY SPACED PISTON MEMBERS The present invention relates as indicated to an electromagnetic pump or motor device and more particularly to an electromagnetic pump having axially spaced solenoid coils about a cylinder operative to reciprocate a piston assembly having axially spaced piston members. Such electromagnetic pump is, in some respects, similar to the pump or motor device disclosed in my copending application Ser. No. 170,448, filed Aug. 10, 1971, now US. Pat. No. 3,740,171.
Pumping or compressing of the fluid by reciprocation of a plunger within a cylinder bore having either closed or selectively closed ends is well known in the art. One of the conventional means of affecting the plunger reciprocation is the helical winding of two distinct solenoid coils about the cylindrical member, with the inner ends of the two coils being slightly longitudinally spaced apart. Reference may be made to the Heftye U. S. Pat. No. 581,204; Winsor U. S. Pat. No. 1,840,994; Cobe U. S. Pat. No. 1,974,262; and Marini, U. S. Pat. No. 3,196,797 for disclosures of electromagnetic piston pumps having axially spaced solenoid coils.
This type of pump can be adapted to given functional requirements by varying the dependent design parameters of piston stroke length, reciprocation rate, and pumping force. If such a pump has a relatively small piston compared to the axial size of the cylinder and coils, the lines of magnetic force for the remote coil must travel increased distances to pull the plunger therewithin. Accordingly, any increase in the stroke for such a piston results in a decrease in both effective magnetic force and plunger reciprocation rate. If, however, the piston is relatively long and extends to a position radially within each of the coils, the increased weight of the piston and the residual magnetic force field present result in reducing piston reciprocation rate while also reducing braking efficiency at the end of the stroke.
Accordingly, it is the principal object of the present invention to provide a positive displacement electromagnetic piston pump, or motor device, having axially spaced solenoid coils which increases pumping force and displacement capabilities over that available in a conventional motor and pump tandem of substantially equal size and stroke length. This object is accomplished by providing a piston assembly having two axially spaced piston members joined together by a nonmagnetic spacer or coupling, such piston assembly being of sufficient axial extent to maintain at least a portion of both pistons radially inside the solenoid coils irrespective of the axial position of the piston assembly within the cylinder bore.
Another important object of the present invention is to provide a fluid control system in association with the electromagnetic piston assembly pump that is responsive to reciprocal movement of the piston assembly simultaneously to draw and pump such fluid during both forward and return movements of the piston assembly.
It is another object of the present invention to provide an electromagnetic pumping or compressing device that may be readily dismantled for maintenance or replacement of any of the parts. Such object is accomplished by the provision of removable but nevertheless accurately positioned solenoid coils and removable valve plate assemblies operative selectively to close off the ends of the cylinder bore.
Other objects and advantages of the present invention will become apparent as the following description proceeds.
To the accomplishment of the foregoing and related ends the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but one of the various ways in which the principles of the invention may be employed.
In said annexed drawing:-
FIG. 1 is an elevation partially broken away and in section showing the piston assembly of the invention in its centered position; and
FIG. 2 is an elevation similar to FIG. 1 showing the piston assembly at the end of its right-hand stroke.
Referring now in more detail to the drawings and initially to FIG. 1, the electromagnetic pump or motor device of the present invention includes a cylinder indicated generally at l, the piston assembly indicated generally at 2, and two solenoid coils indicated at 3 and 4. The cylinder has an .open ended bore 5 and is made from a non-magnetic material, such as nylon, ceramic, or Teflon, that is compatible with the fluid being pumped. Cylinder 1 has a central, radially outwardly extending annular projection or rib 7 which forms two annular stop faces 8 and 9.
Two conventional solenoid coils 3 and 4 are wound within annular housings 11 and 12, respectively, with the inner diameter of such coils being substantially equal to the outer diameter of cylinder 1. The coils are accurately but removably positioned in the axially spaced relationship shown by sliding the same axially inwardly until flange 14 on housing 11 or flange 15 on housing 12 abut stop faces 8 or 9, respectively. The coil housings are made of laminated magnetic material which lamination operates to conduct magnetic lines of flux toward cylinder 1 while breaking up any eddy currents. The housings with included coils may be held in assembled or operative condition by any type of nonmagnetic end stops l8 removably positioned against the axially outer walls of the same, whereby upon radial wqthdrawal of such shoulders coils 3 and 4 may be readily removed from the cylinder for maintenance or replacement. A conventional electric circuit (not shown) is provided alternately to energize coils 3 and 4 to produce separate magentic fields.
The respective magnetic fields are operative alternately to attract piston assembly 2 resulting in reciprocatory axial movement of the same in bore 5. The piston assembly includes two spaced apart cylindrical piston members 19 and 20 joined together in axially spaced relationship by a connecting pin 21. The pistons 19 and 20 are of slightly smaller diameter than bore 5 and are sealed to the inside surface of cylinder 1 for sliding movement by piston rings 22 preferably made from a Teflon compound or the like. The cylindrical pistons are made of a magnetic material having a coating thereon compatible with the fluid being pumped and may be hollow to reduce the weight of the assembly.
The connecting pin 21 is made from a non-magnetic material such as nylon, ceramic or a Teflon compound. The length of the connecting pin and thus the spacing between piston members 19 and 20 may be varied in accordance with the piston stroke desired and the spacing of the coils. In other words, with a predetermined spacing of the coilsand a desired piston stroke, the length of the connecting pin needed may readily be determined. Such pin or coupling must be of sufficient length, however, to result in piston assembly 2 being of sufficient axial extent to position a portion of piston members 19 and 20 radially inside coils 3 and 4, re spectively, irrespective of the position of such piston assembly in bore 5.
The ends of cylinder 1 and consequently bore are closed off and selectively sealed by valve plate assemblies indicated generally at 25. Such assemblies 25 are made from non-magnetic materials and may be pressfitted into the cylinder or attached by conventional fastening means. The fastening means for the valve plate assemblies may be of a permanent or temporary nature, the latter type of fastener permitting removal of the valve plate assemblies for maintenance purposes. At the ends of bore 5, two fluid chambers of variable volume 26 and 27 are formed by pistons 19 and 20, respectively, cylinder 1, and valve plate assemblies 25.
Referring in detail to the valve plate assembly at the right end of the pumping device as viewed in FIG. 1, valve plate 29 has a peripheral inner shoulder 30 which receives the end of cylinder 1 properly to seat such valve plate with respect to the cylinder. Two diametrically offset bores or passages 31 and 32 extend axially through valve .plate 29 to communicate at their inner ends with fluid chamber 27. Check valves 33 and 34 are connected to plate 29 by suitable fastening means and cover the inside and outside ends of bores 31 and 32, respectively. Such check valves normally block fluid flow through such passages and are effectively oppositely biased since valve 33 when open permits fluid flow into chamber 27 while valve 34 when open permits fluid flow from chamber 27. A T-shape adaptor member 36 is connected to the outside surface of plate 29 andis formed with an inlet passage 37 and an outlet passage 38, such passages being in fluid communication with bores 31 and 32, respectively.
The left-hand valve plate assembly is substantially identical to and a mirror image of the right-hand valve plate assembly just described and includes plate 40 with offset axial bores 41 and 42 extending therethrough. Such bores are normally closed by oppositely biased check valves 43 and 44, respectively. Adaptor member 46 defines inlet and outlet passages 47 and 48 which are selectively in fluid communication with bores 41 and 42, respectively.
It will be appreciated that conduits or tubing in the fluid flow system may be attached to the ends of adaptor members to complete thesealed and closed pumpingor compressing device. In atypical refrigeration application of the device, conduits attached to inlet passages 37 and 47 emanate from the evaporator, while conduits connected to outlet passages 38 and 48 lead to the condenser.
A cycle in the operation of the electromagnetic pumping device of the present invention can best be described in context with FIG. 2. The energization of coil 4 creates a magnetic field causing piston to become magnetized and the action of the field in the solenoid on the poles created on piston 20 results in the entire piston assembly moving rapidly to the right in the bore to a position in which piston 20 is within coil 4 at the center of the field of force. The centering of the piston 20 within the field acts as a magnetic damper or brake on the entire piston assembly, with plate 29 being slightly set back from the end of the stroke to preclude contact between the piston and valve plate assembly.
The forward stroke of the piston effected by energization of coil 4 compresses the fluid contained within chamber 27 and pushes the fluid thus compressed through check valve 34 into the fluid flow system as indicated by arrows A. The increased pressure of such fluid is greater than the inlet fluid pressure in passage 37, whereby check valve 33 remains in the normally seated position shown. At the same time, the volume of chamber 26 is proportionately increased by the piston assembly movement to develop a low or negative sealed pressure zone in such chamber. This low pressure is less than the pressure in the fluid flow system whereby check valve 43 is opened to allow entry of fluid through inlet bore 41 as indicated by arrows B, and check valve 44 is seated to preclude delivery of such fluid through passage 42. At the completion of the forward stroke, a portion of piston 19 remains radially inside coil 3 and therefore within a potentially strong magnetic force field.
Thus when coil 4 is deenergized and coil 3 substantially simultaneously energized by the electrical circuit, the magnetic force field of coil 3 will quickly pull magnetized piston 19 and thus piston assembly 2 to the left until the centering effect of piston 19 and coil 3 stops such plunger to complete the piston assembly cycle. Thus the reciprocal movement of the piston assembly is quickly and smoothly effected without complicated electrical systems, springs, end stops or mechanical linkages. The return stroke of the piston assembly cycle has the opposite effect onthe valves shown, specifically, check valves 33 and 44 will open, while check valves 34 and 43 will close. Such disposition of the valves enables the device to draw fluid into chamber 27 through inlet port 33 and to deliver compressed fluid from chamber 26 to outlet passage 44.
The present invention thus permits rapid cyclical movement of the piston assembly since the piston members are always positioned in astrong force field. Moreover, the spacing of the coils and piston members and the non-magnetic cylinder eliminate any sticking or hesitancy in initiating reverse movement which might be caused by residual magnetic force fields.
The present electromagnetic device may be used in any type of environment requiring reciprocal movement of a piston assembly and is, of course, not limited to the specific embodiment shown. For example, a piston rod or saw blade could be connected to the plunger to extend axially beyond the cylinder member.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. An electromagnetic pump or motor device compirising a housing having a bore therein, spaced solenoid coils about said housing adapted alternately to be energized, piston means movable in the bore, said piston means including two piston members axially separated by a non-magnetic spacer member of sufficient extent to position at least a portion of both pistons radially inside the solenoid coils irrespective of the axial position of the piston means within the bore, whereby, when said coils are alternately energized to produce respective magnetic fields, said piston means is alternately magnetically attracted to reciprocate within said bore.
2. The pump set forth in claim 1 wherein the coils are removable from said housing but are accurately held in predetermined axially spaced positions during operation.
3. The pump set forth in claim 2 wherein the housing has an intermediate, radially outwardly projecting rib to form stop faces against which the axially inner ends of the two coils abut accurately to position the same.
4. The pump set forth in claim 1 wherein the housing and coils are generally cylindrically formed with the inside diameter of the coils being approximately equal to the outside diameter of the housing, whereby the coils may be slid onto and off of said housing.
5. The pump set forth in claim 4 further including means to position and hold the coils in axially spaced relationship during operation.
6. The pump set forth in claim 5 wherein the means to position and hold includes an intermediate outwardly projecting rib on said housing forming axially spaced stop faces against which the inner ends of said coils abut accurately to position the same.
7. The pump set forth in claim 6 wherein the means to position and hold includes removable stops against the outer ends of the coils to maintain accurate positioning of such coils during operation.
8. The pump set forth in claim 1 further including end plates associated with said housing to close off the ends of said bore, said end plates selectively communicating with a fluid intake and delivery system.
9. The pump set forth in claim 8 wherein each of the end plates is removable from the bore and includes two oppositely biased check valves, one of such valves communicates with the fluid intake line of the system while the other valve communicates with the fluid delivery line of the system. 1k t