US2194535A - Electric translating device - Google Patents

Description

March 26, 1940. Fv Jl VON DELDEN 2,194,535

ELECTRIC TRANSLATING DEVICE Filed April l5, 1937 7 Sheets-Shee(l 1 55- l Ilm' NIW -|l|"| II 'I |l l ,54 ,Il 67 :I I II 52 'l y l 69 m f INVENTOR ATTORNEYS March 26, 1940. F. J. VON DELDEN 2,194,535

ELECTRIC TRANSLATING DEVICE Filed April l5, 1937 7 Sheets-Sheet 2 BY m MVQMHQW ATTORNEYS March 26, 1940. F. J. voN DELDEN ELECTRIC TRANSLATING DEVICE Filed April 15, 1957 7 Sheets-Sheet 3 f f f f l f f f/ f/ /f/ ATTO RNEYS March 26, 1940.

F. J. VON DELDEN ELECTRIC TRANSLATING DEVICE Filed April l5, 1937 7 Sheets-Sheet 4v s, IIOVDLTSr /dl L [JO /60 n m Q //V INVENTOR /CZo/rf/Vz JVM/ 05mm BY www; www# QW ATTORNEYS March 26, 1940. F, VQN DELDEN 2,194,535

ELECTRIC TRANSLATING DEVICE Filed April 15, 1937 '7 Sheets-Sheet 5 ATTORNEYS March 26, 1940.` F. J. VON DELDEN 2,194,535

ELECTRIC TRANSLATING DEVICE Filed April l5, 1957 7 Sheets-Sheet 6 l i 220 l BY y mmwxm' ATTORNEYS F. J. lVON DELDEN ELECTRIC TRANSLATIG DEVICE Filgad April l5, 1937 7 sheets-'sheet "7 ,L E j 6/ INVENTOR ATTORNEYS Patented Mar. 26, 1940 UNITEI)- STATES PATENT FFiCE ELECTRIC TRANSLATING DEVICE Application April 15, 1937, serial No. 131,023

12 Claims.

This invention relates to electric translating apparatus and especially to such apparatus in which electrical pulsations /are translated into reciprocating motion.

One of the objects of the invention is to provide an apparatus for translating electrical pulsations into mechanical movement with a high degree of eiiiciency.

`Another object of the invention is to provide l a highly efiicient reciprocating motor with few moving parts.

Another object of the invention is to provide van eiiicient reciprocating motor in which the length of stroke may be adjusted with load coni dtiOnS.

Another object of the invention is to provide a reciprocating motor in which the noise level is maintained at a minimum.

Another object of the invention is to provide a reciprocating compressor with novel lubricating and cooling means.

Still another object of the invention is to provide an electric refrigerator in which the compressor for the refrigerant is operated by a re- 5 ciprocating electric motor.

Still another object of the invention is to provide a reciprocating electric motor which will operate on alternating current.

Other objects and objects relating to the method of constructing and assembling the various parts will be apparent as the description of the invention proceeds.

'I'he invention is illustrated in the accompanying drawings, in which:

5 Fig. 1 is a plan view, partly in section, of one form of motor for translating electrical pulsations into reciprocating motion, together with a circuit diagram of the connections;

Fig. 2 is a similar plan view, partly in section,

V9 of a motor adapted to operate on raw alternating current; f

Fig. 3 is a side elevational view, partly in section, of a iiuid compressor embodying the invention; Y

l5 Fig. 3a is an enlarged elevational View of one of the electrical connectors used with the device of Fig. 3; I

Figs. 3b and 3c are plan and sectional elevational views respectively of' one form of piston valve;

Fig. 3d is a plan view o i a modified form of piston valve;

Fig. 3e is a. fragmentary sectional view of a portion of the piston skirt; A

(Cl. 23o-55) Fig. 3f is a fragmentary sectional end view of a modied form of piston assembly;

Fig. 4 is a sectional side elevational view of a refrigerator with the compressor unit of Fig. 3;

Fig. 5 is a diagram showing the electrical and 5 gas connections for the compressor of Figs. 3 and 4;

Fig. 5a is a portion of the diagram of Fig. 5 showing a modication thereof;

Fig. 6 is a diagram showing a modiiied elec- 10 trical circuit;

Fig. 'l is a side elevational view, partly in section, of a double-acting compressorrusing the principle of the invention;

Fig. 8 is a sectional end view of the compres- 15 sor unit of Fig. 7, taken on the line 8 8 of that gure; y,

Fig. 9 is a circuit diagram showing an alternative connection for the moving coil of Figs.

'7 and 8; 20

Fig. 10 is a sectional side elevational view of a diaphragm type of compressor embodying the invention;

Fig. 11 is a sectional plan View o! the compressor of Fig. 10, taken on the line II-II of that figure;

Fig. 12 is an elevational view, partly in section, of a bellows type compressor embodying the invention; and

Fig.- 13 is a sectional, elevational view of still another modified form of dynamic motor.

In Fig. 1 a simple arrangement is shown for utilizing the invention and in which electrical pulsations or alternations are translated into reciprocating motion. In order to accomplish this result I provide an annular magnetic field between a cylindrical core I0, which acts as one pole of the magnet, and a plate II having a hole I2 therein to receive the end of the core, which acts as the other pole. A coil I3 of wire may surt round the enlarged end I0a of the core I0 and the magnetic circuit may be completed by a U-shaped member vI4 of magnetic material, to the central portion ofwhich the enlarged end of the core I0 may be secured by any desired means, as by the shank I5 fitting tightly into a hole I6. The plate I l may then be fastened to the ends ci the U-shaped member I4 in a suitable manner, as by means of screws I1.

I prefer to have the end of the core iii extend 5g) outwardly slightly beyond the plate Il and to provide a groove IIa around the surface thereof at a point about even with the inner edge ci the hole I2. This groove may have a width about equal to one quarter of the thickness of the plate i and may have about an equal depth. The coil I3 may be securely held in place by the plate II, a suitable insulating packing ring I3a being positioned between the plate and coil. The shoulder Ib on the enlarged portion Illa may be preferably chamfered, as indicated, so as not to cut into the coil I3.

A closely wound coil I8 of wire may be mounted for reciprocation in the annular field by means of a cylindrical support I9 which may be made of aluminum, if desired, or some other non-magnetic material, such as stiff paper, and upon which the coil may be cemented or otherwise attached. The support member I9 may have an end wall 20 which may be rigidly attached to a shaft 2I mounted for reciprocation in a bearing 22. The opposite end. of the shaft 2I may be provided witha bifurcated connection 23 to which may be attached any mechanism to be driven by the reciprocating motor, as, for instance, pumps, riveters, or the like, or the reciprocations may be translated, into rotary motion in a manner which will be clearly understood.

When the coil I3 is energized by direct current an intense magnetic field is set up in the air space between the plate II and the magnetic core III. When an alternating current is passed through the coil I8 a magnetic field is set up around the coil which is at right angles to the direct current eld and causes the coil to move in one direction for one-half of the alternating current cycle and in the other direction for the other half. Thus the coil is caused to reciprocate in the field and carries with it the supporting member I9 and the shaft 2I, and thus reciprocates any mechanism connected to it.

In order to permit this apparatus to operate on alternating currentpower mains I may provide a transformer 32 having a primary winding 33 and three secondary windings 34, 35 and 36. A rectifier tube 3l may have its lamentary cathode 38 energized by means of the winding 34, while the two anodes 39 and 40 may be connected to the ends of the coil 35. The center tap of the coil 35 may be connected to one side of the coilv I3, while the other side of the coil may be connected to the filamentary cathode 38. A pair of filter condensers 4I and 42 may be connected across the leads to the coil I3 to filter out pulsations produced by rectication, as will be understood by those skilled in the art. With this arrangement the coil I3 is provided with direct current when the transformer 32 is energized.

In order to provide the coil I8 with alternating current I connect it to the secondary winding 36, preferably using a potentiometer 43 yto 4control the amount of current flowing in the coil I8. With the potentiometer connected as shown, across the secondary 36, with the coil I8 connected between the arm 43a of the potentiometer and one side thereof, it is possible to adjust the voltage on the coil I8 from zero to the maximum voltage produced by the secondary 36. 'I'his adjustment of voltage of the coil I8 provides a means to control the force whichis acting on the coil I8, and thus a means to adjust the power of the motor.'

Under some conditions it may be desirable to dispense with the rectifier tube and transformer 32, described in connection with the last figure, and operate the field coil on alternating current; An arrangement for doing this is shown in Fig. 2. The same principleof the reciprocating coil is .used in this gure in which a Ulshaped magnetic member 50 may be provided with a coillil surroundingthe central pole piece 52, the latter being attached to the housing 50 at the center, similarly to that described in connection with Fig. 1, the

plate 53 having a hole 54 in the center thereof to receive the end of the pole piece 52. The ends of the plate pole piece 53 may be attached to the ends of the member 58 by means of suitable screws 55.

Also, similarly to the construction of Fig. 1 the coil 56 may be supported in the air gap between the pole piece 52 and the plate 53 by means of a cylinder- 51, of aluminum or other light weight non-magnetic material, which may be secured to the shaft 58 supported for reciprocation in the bearing 59. This shaft may terminate in a bifurcated member 60 which may be attached to the mechanism to be driven. A compression spring 6'I may be mounted around the shaft 58, between the bearing 59 and the cylinder 51, so that the shaft and .cylinder may be urged by the action of the spring towards the right with the coil at its farthermost position in the magnetic field.

The coil 5I is intended to be energized directly by alternating current received from the volt power mains. In order to energize the coil 56,

however, I may provide another coil 68 wound on means of a potentiometer 69, which maybe used to control the voltage of the coil and therefore to adjust the power of the motor.

The alternating current in the coil 5I causes the field to alternate. At the same time, the current in the coil 56 is alternating; hence the force tending to move the coil `56 is always acting in the same direction. Connections to the coil 56 are made so that the proper phase relation is obtained between the current in the two coils which will cause the coil 56 to move in an outwardly direction or towards the left, as shown in Fig. 2, for each half of the alternating current cycle. As the coil moves against the action of the spring 61, the spring will return the coil to its innermost position again when the force causingit to move approaches zero or at each half of the alternating current cycle.

It will be seen from the above arrangement that the device of Fig. 2 may be operated directly onalternating current Without the use of any rectifier or filter circuit. The pole pieces may be made laminated, if desired, to reduce heating effects.

An important use for the reciprocating motor itself may be to operate a reciprocating device, such as a compressor, which might be used in an electrical refrigerating apparatus. Such a compressor may consist merely of a reciprocating piston attached to the coil and Vmay thus eliminate all rotating parts.

In Fig. 3 I have shown such a compressor adapted to be used in an electric refrigerator. In this figure a magnetic U-shaped member 15 has a core member 16 atached to it, as by means of the shank 'I1 on the lower end ofthe core which may be threaded into a hole 'I8 in the member 'l5 to form a rigid connection. A coil 80 may surround the core I6 to energize it, and a plate 8| may be provided with a hole 82 to fit over the upper endv of the core 16 and leave an Aair. space between it and the core. The plate 8l may rest upon the top ofctle two legs of the member 'Il and may be secured by means of screws, or in any other desired manner, such as by welding.

The core member I6 may extend slightly above the plate SI and may have an enlarged lower portion 03 around which the coil 80 may be wound. Also I prefer to provide a groove 10a around the core member about even with the lower edge of the plate 0I and lhaving a width and depth about equal to one quarter of the thickness of the plate. This `groove appears to aid in concentrating the magnetic flux in the annular space between the plate and the end oi the core 10.

The coil tt may be rigidly held in place by the plate Si with a gasket 80abetween the plate and the coil which makes a substantialy liquid tight seal between. the coii and plate for a purpose to be hereinafter described.

The cylinder c4 for the compressor may be mounted upon. the top of the plate 8i by means of four legs Et, which may extend outwardly and downwardly from the sides thereof, and have feet tt which may be secured to the plate 0I by means of suitable screws El. A valve disc 88 may rest on top of the cylinder, a suitable gasket being provided in between the cylinder anddsc, and this disc may carry a pair of thin spring steel valves tt adapted to overlap each other on top of the disc and to cover a hole 90 in the disc. The valves may be held in position by means of the screws 9i.

On top of the disc tti I provide a dish-shaped head i2 which may be made slightly larger indiameter than the disc S8 with a dange to lt over the disc, a suitable gasket being used in between A, pipe connection Q3 may be formed integral with the head communicating with the under side thereof to forni the outlet for the compressor.

The head 92 may be secured in place by means of a yolre 941 which may be anchored to the cylinder by rods 95, the rods having threaded lower ends which engage tapped holes in the upper part o the legs, as shown, and threaded upper ends which may be provided with securing nuts 95o. A set screw 9d at the center of the yoke may engage a recess 91 on the top of the head, and by tightening the set screw the head 92 and valve disc 08 will be forced securely against the top ci' the cylinder. If desired, a second set screw 98 may be used to lock the rst one.

The piston t9 may comprise a hollow casting, preferably of aluminum, which may have a cylindricai portion I0@ at its upper end adapted to have a sliding iit in the cylinder 84. The lower end of the portion E00 may have a plurality ci large ports Ilii which may form the inlet ports for the compressor.

A thin steel disc valve IUE (Figs. 3b and 3c) may be secured on the top of the piston by means of a central boit E03 and may cover the openings |04 in the top thereof. In order to insure the operation of this valve I preferably undercut the head oi the boit I03 as at Hita which causes the periphery of the disc to rise slightly away from p the top surface of the piston and reduces the tension of the edge of the disc thereagainst. For use with a less dense gas I may prefer to use the valve illustrated in Fig. 3d where a thin steel cross itu` is used in place of the disc, the ends of the. cross covering the holes in the top of the piston.

Below the ports IIEI the piston may be some what larger in diameter and may be provided with a skirt i046 which may extend into the annular space between the pole piece 'I0 and the plate 8 I and have a reduced section |05 to receive the wires of the coil E00.

I may compensate for the weight of the piston and the pressure of the gas above it by means ci a coil spring 99a inside the piston and secured to the top of the piston by the valve bolt |03 and to the pole piece it by a suitable screw I00a.

When the winding 80 is energized by direct current, producing an. intense field across the air space between the plate 8l and the core mem-1 ber 10, and alternating current is run through the coil |00, movement of the coil will result, thereby reciprocating the piston in the cylinder.

Fluid is introduced into the compression space of the cylinder through the openings IOI in the piston and the-spring valve E02 in the top thereof. Fluid leaves the cylinder through the ap valves 89 in the disc 80 and the outlet connection 93 in 'the head 92.

In order to make the electrical connections for the moving coil I may use a pair of resilient connectors |01 extending between vthe skirt |04 of the piston and insulating blocks |08 mounted on the outermost edge of the plate 8i. Each of the connectors |01 (Fig. 3a) may comprise one or more corrugated ribbons, preferably one, |09, of phosphor bronze and, if additional suport is required, one or more others, I i0, of steel, laid one upon the other with the outer ends secured to the insulating block IGS by means of a screw I I I, the screw also holding a lug SI2 to which the connection may be made. The inner end of the connecn tor I0l may be bent upwardly and secured to the piston skirt 04?) by a rivet or bolt lili (Fig. 3e) and insulated therefrom by suitable insulating washers H5. The corrugations on these connec- 'the wires may be cemented, the wire for the lowermost end of the coll thus passing under the turns thereof. A

Inasmuch as the connector applies a slight sidewise force against the pliston when the piston reciprocates, I preer to use two connectors, one opposite the other, so that these effects will be balanced out. However, under certain conditions, I may dispense with one connector entirely and ground one end of the coil directly to the piston so that one side of the transformer seeondary supplying current to the coil may be attached to any portion of the motor or container, whilel the other' side of the coil will be fed through the resilient connector.

I may desire to operate the compressor with its driving mechanism as shown inside of a drum or container H0 which also may act as a reser. voir for lubricating oil and the refrigerating fluid. This container H6 may comprise a lower compartment H'E in which the magnetic member 'I5 may resiliently rest upon coil springs I I3 pro= vided for that purpose. In order to support the springs I may prefer to mount the whole dynamic motor upon a plate I It which may be screwed or otherwise attached to the magnetic member 'I5 and which may be provided with lugs I 20 around Sii which the springs l may fit. Corresponding lugs |2 I, spotwelded or otherwise attached inside the compartment l1 to the bottom thereof, may receive the lower ends of the springs. An upper compartment |22 may be sealed to the lower compartment by means of flanges |23 and |24, respectively, formed on the upper and lower compartments and held together by means of screws |25, a suitable gasket |26 being used to make a gas-tight connection and stiiening rings |2'| and |28 being used, if desired, above and below the flanges.

In order to provide lubrication for the moving piston I prefer 'to substantially fill the lower compartment with some lubricating oil |29, such as Russian mineral oil, so that the eld coil 80 and moving coil |06 operate in the oil as well as the lower skirt |0411 of the piston. Reciprocation of the piston will cause oil to splash up and lubricate the upper portions thereof. rPhe rapid movement of the coil |06 in the circulating oil prevents the coil from overheating and permits the use of a much larger current in the coil than would be possible otherwise with the same size wire. This aids in maintaining a high degree of eiiciency, as the more current that can be passed through thecoil the greater will be the power generated.

The upper compartment |22 of the container I6 may be provided with an inlet connection |30 by means of which the refrigerant may enter it, and an outlet connection |3| may be provided in the lower compartment ||1 and may be connected to the cylinder outlet connection 93 by means of a length of tubing |32 andsuitable t tings. The tubing may pass once or twice around the whole motor assembly to give it resiliency to permit movement of the motor within the con'- tainer.

Vapor then flows into the container I6 through the inlet connection |30 and fills the space above non-magnetic material, such as brass,

the oil |29. It is therefore free to pass into the piston 99 and up through the valve |02 into the compression space of the cylinder as the piston makes its downward stroke. Movement of the piston in an upwardly direction compresses the vapor inside of the cylinder into lgas and forces the compressed gas through the valve disc 88 and the outlet connection 93 in the cylinder and through the pipe |32 and the container outlet connection |3|.

Electrical connections may be made to the dynamic motor through the lower wall of the container by means of terminals which may be secured in the wall of the lower compartment |I1. Thus a pair of terminals |35 and |36 which are suitably insulated from the walls of the container and which form a gas-tight `lead-'in through the wall thereof may be used to connect the Ilield winding 80, while a pair of similar ter- I minals |3`| and |38 may be used for completing the circuit to the resilient connectors |01 for the moving coil. If one end of the moving coil is connected directly to the piston, only one of the terminals |31 and |38 need be used, the other connection being made to any metal part of the container.

I have found it desirable'to eliminate all stray magnetic fields so as to concentrate the magnetic flux as much as possible in the annular space between the central pole and the topplate. Therefore I prefer to make the cylinder 84, the valve disc 88 the head 92, and the yoke 94, as well'as the upper part of the container ||6 of I have found that this not only improves the emciency of the whole apparatus but also prevents certain diiiiculties from arising, as, for instance, magnetic sticking of the exhaust valve if the cylinder is made of iron or steel.

In order to have a compressor of high efciency it is important to have the compression'space in the cylinder as small as possible at the end of the compression stroke. Hence the various parts should be so designed that the upper end of the piston closely approaches the 'valve disc 08 at the upper end of its stroke when operated at maximum power. The strength of the spring 99a is also important in bringing about this condition without knocking of the piston at either end of the stroke.

Inasmuch as the oil in the annular space between the core and the plate is trapped therein' by the gasket 80a it has a cushioning effect on the piston which prevents the lower edge of the piston from striking the shoulder of the core on its downward stroke, especially under changing load conditions.

Fig. 3f shows a modified form of the construction wherein further use is made of the oil cushion. Here the core 11a is made similar to the core 1B of Fig. 3 with a groove Hb to receive and trap the oil. However the plate 8|a may be provided with ducts 8|b and 8|c extending through the plate from edge to edge, parallel to and near the under surface thereof. These ducts open into the hole 82a about even with the groove 11b to transmit oil to and from the groove. When the piston skirt |04c moves in the annular space between the plate and core, oil is caused to circulate back and forth through these ducts giving a continuous movement to all the oil in the container I6 which insures cooling of the motor.

If desired, I may provide a hole B2b in the top of the plate communicating with the duct 8|c in which may be screwed a pipe 82c which may extend upwardly and be bent at the upper end towards the center of the upper container |22.,

'I'his pipe may have a nozzle 82d at the upper end so that oil forced through it will be directed against the top of the container |22. A plug 83a having a small hole therethrough may be threaded into the outer end of the duct 8|c soV that most of the oil forced through the duct will pass up through the pipe 82e although some will pass through the plug.

With this arrangement oil is not `only continually circulated about in the lower container but is also sprayed against the inside wall of the upper container 22 so that vibration of this upper container, which would normally be in contact only with the vapor of the refrigerant,

` is dampened and the noise level of the whole apparatus is thus reduced.

Oil is forced in and out of the duct 8| b at the vsame time the oil is sprayed from the pipe 82e,

but if desired a valve 83h maybe placed in the l outer end of the duct 8|b to make this duct always act as the inlet.

In Fig. 3f a modified form of thepiston is also shown. The wall |001) between the small end |00d and the skirt |04c may have an angle of about 45 and the upper edges of the core lla may be chamfered to conform to this angle. The top of the core may be provided with a recess 0 |a to receive oil, and a plurality of holes |00c may be provided around the top of the vpiston skirt to let oil out when the piston comes down. I have found that although the oil level is about as in' dicated by the dot and dash line |29 of Fig. 3, the oil inside the piston rises considerably above the top ofthe core. The action of the oil coming through the holes |c dampens the lower end of the piston stroke and reduces the tendency of the piston to strike the core. With this arrangement the coil spring within the piston may in some cases be eliminated.

The modified parts shown in Fig. 3f may be substituted for the corresponding parts of Fig. 3 for use as a compressor in an electric refrigerator.

In Figs. 4 and 5 the compressor of Fig. 3 is shown mounted in a refrigerator |39 having a compartment |40 in the base to house the mechanism and a cold compartment |4| in which the freezing coils |42 may be suspended. A pipe |43 may extend upwardly at the rear of the cabinet to deliver the condensed and liquefied gas from the bottom of the liquid receiving tank i44 to the expansion valve |42a at the inlet to the freezing coils |42. The top of the receiving tank 44 may be connected by means of a pipe |45 to the bottom of a condenser |46 which may be connected to the outlet connection |3| of the compressor unit. A pipe |41 may connect the inlet |30 of the compressor unit with the outlet of the freezing coils |42 and may be located at the rear of the cabinet. Similarly to the circuit diagram of Fig. 1, I preferably provide for the refrigerator a transformer |48 which may have a primary coil |49 connected to the power mains through a thermostatic switch |50 which turns on and off the apparatus as the temperature fluctuates. Any suitable thermostatic switch may be used for controlling this operation, as, for instance, the temperature-operated device I which may be connected by suitable levers |52 and rapid action lever |53 to device is well understood.

O'ne secondary |55 of the transformer may be used to energize the iilamentary cathode |56 of the rectifier tube |51, the anodes |58 of which may be connected to opposite ends of the high voltage coil |59 of the transformer. The midtap of the secondary |59 may be connected to one side of the field coil 80, while the other side may be connected to the cathode |56 of the rectifier. A pair of condensers |60 and |6| may be used to filter out the pulsations in the D. C. supply from the rectifier. Another winding |62 on the transformer |48 may be used to supply the current for the moving coil |06, this winding being preferably connected across the end terminus of a potentiometer |63, while the moving coil |06 may be connected between one end terminal of the potentiometer and the moving arm |64. The circuit arrangement is exactly the same as described in connection with Fig. 1 with the addition of the thermostatic valve to turn on and off the operating current.

The transformer |48, rectifier tube |51 and condensers I 60and |6| may be positioned in close proximity within the mechanism compartment |40 of the refrigerator, and may be positioned within any suitable enclosure, as, for instance, the

vmetal can |65. The controlling potentiometer may be conveniently located at the top of the cabinet, as s hown, the wires for connecting it to the transformer |48 and moving coil |06 being led down to the container |65 in any convenient manner.

The potentiometer used in the circuit of Fig. 5 may be omitted if desired, as shown in Fig. 5a, by

taking taps |62a oif of the secondary |62 with a suitable switch |63a to select any desired tap.

,The advantage of eliminating the expensive potentiometer will be evident. The switch |63a may be substituted for the potentiometer |63 shown at the top of the cabinet in Fig. 4.

The circuit arrangement described above will cause the compressor to operate at a rate of sixty strokes per second when sixty cycle current is used. By a simple circuit arrangement I may double the rate of operation and a circuit diagram for such an arrangement is shown in Fig. 6. Here a transformer' |66 is shown having secondaries |61 and |68 connected to the rectifier tube |69 in the Same manner as shown in Fig. 5. A secondary may be used to energize the moving coil through a potentiometer |1| when a double throw switch |12 is in its uppermost position. When in such position the potentiometer |1| receives sixty cycle alternating current exactly the same as in the preceding figures.

When the switch is in its lowermost position, however, the potentiometer is connected across the rectier tube |69 through a high resistance |13 of approximately ten thousand ohms and a condenser |14, so that the potentiometer receives two direct current impulses for each cycle. The low potential side of the resistance |13 may be connected to ground through another high resistance |15, also in the order o f ten thousand ohms. The low side of the rectifier may be connected through a low resistance |16 of about 300 ohms to ground.

In this arrangement I have shown an amplifier tube |11 interposed between the potentiometer |1| and the moving coil of the motor, (not shown in this figure) and this tube may be of the 6L6 type having a filament |18 which may be energized by a separate winding |19 on the transformer |66. 'I'he cathode |80 of the tube may be grounded, while the anode |8| may be connected through the primary of a transformer |82 to the high side of the rectifier |69 through the dynamic motor field coil which is indicated at |83 and which may have a resistance of about 1000 ohms and a current carrying capacity of about 150 milliamperes. The secondary of the transformer |82 may be directly connected to the moving coil. The screen grid |84 of the tube |11 may be connected to the high side of the primary of the transformer 82, and a suitable condenser |85 may connect this point to ground. The control grid |86 of the tube |11 may be connected to the arm of the potentiometer |1|.

With the arrangement just described the field for the magnet is energized by the plate and screen grid current of the amplifying tube |11 which is used to amplify the variations of potential across the potentiometer |1| before they are introduced to the moving coil. While one amplifier tube is shown, others may be used in cascade under certain conditions, and such amplifier tubes may also be used with the circuits of Figs. 1 and 5.Y

In using a refrigerator embodying the invention it is possible to vary the length of the stroke by adjusting the potentiometer in the moving coil circuit, as the less voltage delivered to the moving coil the smaller the force acting on it. Hence, while the frequency or reciprocation of the piston remains the same the amount of fluid which it handles may be increased or decreased, and therefore the freezing speed of the refrigerator may be changed. While I have found the circuit of Fig. 5 to be suicient to adjust the freezing speed to a greater degree than mechanical refrigerators now in use, I have found that the speed may be greatly augmented by the circuit of cylinder 84, already described, may be horizontally mounted on a steel plate |92 with their open ends facing each other. The cylinder |90 may be supported on a pair of legs I 93 while the cylinder |9| may be supported on a pair of legs |94, these legs having feet |95 and |98, respectively, secured to the plate by suitable screws or bolts |91 and The outer ends of the cylinders |90 and |9| may be provided with valve discs |90a and |9|a, respectively, which may be exactly similar to the valve disc 88 of Fig. 3, and cylinder heads 200a and 20|a may be suitably secured to the cylinders by means of a plurality of bolts 202a and 203a spaced around the 'cylinders and engaging lugs formed on the cylinders and heads for that purpose. L

The outlet connections 204a and 205a of the cylinders |90 and 19| respectively may be joined together by a T fitting 20611 so that a common outlet is provided for both cylinders.

. A piston |99 may have a cylindrical portion 200 at one end, adapted to have a sliding iit in the cylinder |90, and a cylindrical portion 20|, at the other end, adapted to have a sliding fit within the cylinder |9|. Each end of the piston is closed except for openings 202 and 203 which may be covered respectively by valves 204 and 205. The valve construction may be similar to that already described in connection with the-single acting -device.

The central portion 206 of the piston |99 may be larger in diameter than the diameter of the ends thereof, and portions of the walls may be cut out as at 201 and 208 to form the intake ports for the piston. A coil 209 may be wound around the central portion 208 and constitutes the moving coil to reciprocate the piston.

One pole for the .magnetic eld for the coil 209 may comprise an internal core member 2| 0 which is large enough in diameter so that.the central portion 206 of the piston has a sliding t thereon, and which may be provided with two extensions 2| and 2| 2 for supporting it in position. These ends may extend axially from the midpoint of the piston to a point falling within the cutout portions 201 and 208 of the piston, -so that supporting posts 2|3 and 2|4 may be provided for the core which may be threaded into tapped holes in the core ends. 'I'he lower ends of the posts 2|3 and 2|4 may have threaded shanks which pass through holes in the plate |92 and may be secured on the lower side thereof by means of the nuts 2|5 and 2|6. The core member2|0 forms one pole of the magnetic field andthe supports 2|3 andf2|4 as ,well asthe'plate |92 form a portion of the mag'n'etlc path.

'I'he other pole of the magnet may comprise a rectangular plate 2|1 provided with a-hole 2|8 in which the coil 209 may loosely fit. .This plate .'may be, supported upon a single post 2| 9 which may be suitably secured to the plate |92`\and which may be'provided with a surrounding coil 220 to energize the magnetic field. 'I'he post 2|9 supports the plate 2|'1. in spaced relation to the core 2|0 and surrounding coil support 206.

I have found it expedient in assembling the double acting pump, as just described, to make the piston |99 in two parts which may be threaded together somewhere in the central portion 206, as indicated at 22|. The core 2| 0 may then be inserted in one-half of the piston before the other half is attached thereto.

The electrical connections may be made by resilient connectors 222 and 223 (Fig. 8), which may be exactly similar to those already described, and connected in the same manner. The coil 209A may, in some instances, be wound in two sections, each lwound in the same direction forming one coil which may be connected as already shown in Fig. 5. However, I may prefer to connect this coil in a slightly different manner. Fig. 9 shows the coil with the extreme ends connected to a potentiometer 224 which is in turn connected across a coil 225 forming the current supply secondary. The central arm 226 of the potentiometer may be connected to the midpoint 221 of the coil. By adjusting the arm on the potentiometer an adjustment of the position of the coil in the magnetic field may be obtained, and therefore an adjustment of the position of the piston. The

length of the stroke may also be controlled in this manner.

The double acting compressor just described may be substituted for the single acting pump of Fig. 3 by connecting the outlet T fitting 206a to the resilient outlet pipe |32 and by connecting the leads of the field coil 220 to the terminals |35 and |36 and the connectors 222 and 223 to the terminals |31 and |38. Then when direct current is passed through the coil 220 the plate 2|1 becomes one pole of the magnetic eld, while the core 2|0 becomes the other pole, and an intense field is produced in the annular space surrounding the coil 209. Alternating current in the coil 209 will cause `the piston to move back and forth in the two cylinders, and, as the outlets of both cylinders are connected together, a compression pulse is produced in the compression line for movement of the piston in each direction, making one hundred and twenty pulses per second for sixty cycle alternating current.

While the invention may be preferably used in connection with a piston type compressor, I may also use it with a diaphragm compressor, as shown in Fig. 10. In this arrangement the dynamic motor 228k may be exactly the same as that described' in connection with Figs. l, 2 or 3, the moving coil being mounted on a reciprocating member 229. A rod 230 may be rigidly attached to the member 229 and may have its other end connected to the center of a diaphragm 23| which is supported on a suitable bracket 232 `provided for that purpose and attached to the top plate of the motor. A compression head 233 may be mounted on top of the diaphragm leaving a small compression space 234 above the diaphragm and having inlet and outlet connections 235 and 236 with suitable inlet and exhaust valves 231 and 238 respectively for controlling the movement of the fluid. As the diaphragm springs up and down alternate compression and suction will cause `fluid to flow in the direction of the arrows, as will be clearly understood.

In Fig. 12 I have shown the invention incorporating a bellows type of pump. Here the motor 239 may be exactly the same as shown in connection with Fig. 10, andthe pump head 240 may reciprocating power member 242-and open at its upper end where it may be secured to the head member 240 which may be supported from the top plate of the motor by means of the frame or bracket 243. 1

I prefer to construct the bellows in such a manner that it will provide a minimum of compression space. To this end a plurality of discs may be arranged in pairs with the discs of each pair, as for instance, 242a and 243a, secured together at their outer edges by folding the edges over and welding. The lower disc 243e of one pair and the upper disc 244e of an adjacent pair may be Welded at their centers to a Washer 245e. to make a gas tight joint. The other pairs of discs may be connected similarly. All of the discs, except the bottom one, may have a small hole 246er at the center so that when the bellows is collapsed the only space left is the space in the holes.

Reciprocation of the member 242 will cause the bellows to expand and contract, producing the pumping action in the compression head 26@ i and causing liquid or gas to ilow therethrough.

While in most of the gures I have shown dynamic motors in which the field is energized by direct current and the moving coil by alternating or pulsating current, I wish to make it clear that this arrangement may be reversed, the field being supplied with alternating or pulsating current and the moving coil with direct current. In this case, however, it is preferable to laminate the magnetic circuit so as to reduce eddy currents and prevent Aoverheating of the magnet.

I also provide a meansto adjust the stroke of the reciprocating part by the use of the potentiometer (Figs. i, 5 and 6) or the tapped transformer secondary (Fig. 5a.) in the moving coil circuit. I may accomplish this same result, however, if desired, by controlling the amount of current in the eld coil while maintaining constant the current in the moving coil, or I may adjust the value of both simultaneously.

In some cases I may dispense with the eld winding and use a field produced yby a permanent magnet. Fig. 13 illustrates one form of a permanent magnet motor. The U-shaped member 26|, center core 262 and top plate 263 are preferably made of some metal or alloy, such as an alloy of steel and cobalt, which may be highly magnetized and is capable of holding its magnetism for a long period of time. A similar annular space is provided between the core 262 and the plate 263, as has been illustrated in connection with the motors alreadyV described, and a moving coil 264 wound on a thin cylinder 26d is mounted for reciprocation in this space. The cylinder 265 may be attached to the piston of a compressor or to any other mechanism to be driven, and the electrical connections to the coil 264 may be made in the manner described in connection with the other figures. This type of motor may be substituted, ii desired, for any of those illustrated.

It may be more convenient to provide an annular conguration for the magnetic eld and therefore for the moving coil. The invention c'omprehende, however, the use of any desired configuration for the eld and coil, which may be made for instance, oval, square, triangular,

octagonal, etc. to suit any particular construction of parts.

It will be evident from the description of the various gures that I have provided a dynamic motor which may be used to translate electrical impulses into mechanical reciprocating or rotary motion and which may be particularly adapted for use with compressors or other reciprocating devices. I have found the motor to be excellent in operating the compressor of an electric refrigerator Where it has many advantages. Among these may be listed the fact that the whole apparatus may be hermetically sealed with the piston as the only moving part, and the stroke of the piston may be readily adjusted by adjusting the current flowing through the moving coil. This adjustment of the piston stroke permits the output of the compressor to be varied without changing the frequency of reciprocation, and hence freezing time in an electric refrigerator may be increased or decreased at will.

Many other variations of the invention may be used without departing from the spirit thereof,

and I do not, therefore, desire to limit the invention other than by the appended claims.

What I claim is:

1. A fluid compressor unit comprising an electro magnet having pole pieces cooperating tc form a tubular air gap therebetween, an elongated conductor wound in a tubular form to fit in said air gap, rnean'svto mount said conductor for reciprocation in said air gap, means to energize said electro magnet with direct current, means to pass an alternating current through said conductor, a compressor having a stationary member and a movable member, and means to operatively connect said conductor to said movable member. g

2` A compressor comprising an electro magnet having pole pieces arranged to form a tubular air gap therebetween, a conductor wound in a tubular form to fit into said air gap, means to mount said conductor for reciprocation in said air gap, a cylinder, and a piston mounted for reciprocation in said cylinder and rigidly attached to said conductor.

3. A compressor unit comprising an electro magnet having pole pieces arranged to form a tubular air gap therebetween, an elongated conductor wound in a tubular form so as to Iit into said air gap, means to energize said electro magnet with direct current, means to pass alternating current through said conductor, a cylinder 'supported in spaced relation from said electro magnet, 'and a piston mounted in said cylinder and rigidly attached to said conductor.

4. A compressor comprising an electro magnet having pole pieces arranged to form a tubular air gap therebetween, an elongated conductor wound in a tubular form so as to t into said air gap, a double ended piston rigidly attached to said conductor, and a pair of cylinders, one cooperating with each end of said piston.

5. A uid compressor unit comprising an elec.- tromagnet having pole pieces arranged to form a tubular air gap therebetween, an elongated conductor wound in a tubular form so as to t into said air gap, a pumping device comprising a stationary part and a moving part, means to rigidly attach said stationary part to said electromagnet, means to rigidly attach said moving part to said conductor, a transformer having a primary adapted to be connected to a source of alternating current, a secondary on said transformer, means to connect said secondary to said movable conductor, a second higher voltage secondary for said transformer, means to rectify the current produced'by said second secondary,

and means to energize said electromagnet' with said rectified current.

6.v A compressor having a stationary part and a linearly moving part, an electromagnet rigidly secured to said stationary part and having pole pieces arranged to form a tubular air gap therebetween, said tubular air gap being on the axis of movement of said moving part, an elongated conductor Wound in a tubular form so as to fit into said air gap, means to rigidly secure said conductor to said moving part so that reciprocation of said conductor will cause reciprocation of said moving part, means to energize said electromagnet, and means to pass current through said conductor, said means comprising at least one resilient electrical connector rigidly supported at one end on said electromagnet and at the other .end on said movable conductor.

7. A compressor unit comprising a cylinder, having an open end, an electromagnet rigidly attached to said cylinder and having pole pieces arranged to form a tubular air gap therebetween, the axis of which coincides with the axis of said cylinder, and said air gap being positioned in front of the open end of said cylinder, a conductor wound in a tubular form so as to t into said air gap, a piston mounted for reciprocation in the open4 end of said cylinder and rigidly attached to said conductor, so that said piston forms the support for said conductor in said air gap, means to energize said electromagnet, and means to energize said conductor, one of said means sup` plying pulsating current.

8. A compressor unit comprising an electromagnet having pole pieces arranged to form a tubular air gap, a cylinder mounted in spaced relation to said electromagnet and having an open end facing said electromagnet, the axis of said cylinder coinciding with the axis of said air gap, a piston mounted for reciprocation in the open end of said.cylinder, a skirt on the outer end of said piston having a tubular form adapted to t into said air gap, a coil of wire wound around said skirt, means to energize said electromagnet, and means to energize said coil, one of said means supplying pulsating current.

9. A` compressor for an electric refrigerator comprising a member having a compression chamber therein, a movable member associated with said compression chamber to alter the space therein when said movable member is moved, a conductor Wound in a tubular form and operatively connected to said movable member, means to create an intense tubular magnetic field so shaped that said tubular conductor will t therein,. means to position said magnetic eld so as to include said tubular conductor therein, means to energize said tubular conductor, and means to vary the energization thereof.

10. A compressor for an electric refrigerator comprising a cylinder, a piston mounted for reciprocation Within said cylinder, an electromagf, net having pole pieces arranged to form a tubular air gap therebetween, a tubular member attached to said piston and adapted to reciprocate freely in said air gap, a conductor Wound upon said tubular member, means to energize said electromagnet, meansv to energize said conductor, one of said means supplying alternating current, and means to vary the current passed through said conductor.

11. An electro dynamic compressor comprising a member having a compression chamber therein, a diaphragm closing said chamber, van electromagnet having pole pieces arranged to form a tubular air gap therebetween, an elongated conductor wound in a tubular form so as to t into said tubular air gap, said conductor being rigidly attached to said diaphragm, means to energize said electromagnet, and means to energize said conductor, one of said means supplying pulsating current.

12. A compressor comprising a member having a compression chamber therein, a bellows attached to said member and cooperating with said compression chamber so as to vary the iiuid pressure therein as said bellows is expanded and contracted, an electromagnet having pole pieces arranged to form a tubular air space therebetween, an elongated conductor wound in a tubular form to ilt into said tubular air space, means to operatively connect said conductor with said bellows, means to energize said electromagnet, and means to energize said conductor, one of said means supplying pulsating current.

FLORENZ J. voN DELDEN.

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