US1978866A - Fluid pump and drive means therefor - Google Patents

Description

Oct. 30, 1934. w O 1,978,866

FLUID PUMP AND DRIVE MEANS THEREFOR Filed Feb. 6, 1933 4 Sheets-Sheet l INVENTOR v Wilhelm mu iy Oct. 30, 1934. w KQN|G 1,978,866

FLUID PUMP AND DRIVE MEANS THEREFOR Filed Feb. 6, 1933 4'Sheets-Sheet 2 Y .5 fe, I O O J 3 l7 n O O 0 INVENTOR Wilhelm 71132127 BY SW7? 2* aria 57 ATTORNEY Oct. 30, 1934. w. KONIG FLUID PUMP AND DRIVE MEANS THEREFOR 4 Sheets-Sheet 3 Filed Feb. 6, 1933 I A R N A INVENTOR Wilhelm Iffim I 00 J m fl W 7 ll 7 9 8 a Z 4 m 5 5 .J 5 5 w 0 .0 5 5 M: 6 :u 2 J 8 .2

Oct. 30, 1934. KQNIG 1,978,866

FLUID PUMP AND DRIVE MEANS THEREFOR Filed Feb. 6, 1933 4 Sheets-Sheet 4 INVENTOR 14 zlizelm 71*0/22 A ORNEY "Patented Oct. 30, 1934 UNITED-STATES PATENT OFFICE FLUID rum AND DRIVE MEANS rnnnnron Wilhelm iiinig, Frankfort-on-tlie-Main, Germany, assignor to Alfred Teves Maschinen- & Armaturenfabrik G. m. b. H., Frankfort-onthe-Main, Germany Application February 6, 1933, Serial No. 655,327

In Germany March a, 1931 p 20 Claims. (CL 23055) This invention relates to fluid pumps and compressors and to driving means therefor. More particularly it concerns itself with an improved compressor adapted to be directly actuated electro-magnetically by a rectilinearly reciprocable armature forming part of an improved magnetic motor. The invention further contemplates theprovision, in combination with such a compressor, of a magnetic motor incorporating an armature whose natural period of oscillation is normally in resonance with the pulsating or alternating current by which the motor is energized, whereby the inertia of the moving a ts is utilized to assist in driving the piston of the compressor, and the power applied is expended only in overcoming friction and air resistance once the-compressor is in motion.

An important object of the invention is also the provision of means for damping or con- 20 trollingly restricting the amplitude of the oscillations of the reciprocating parts when they approach dangerous proportions, and for automatically proportioning such damping to the extent to which the amplitude of the oscillations exceeds a desired maximum, thus preventing injury of the reciprocating parts. a

.A further object is the provision of means for temporarily relieving the load on the compressor if it should become so great as to limit the travel of the reciprocating parts beyond a desirable Another object is the provision of means for constantly providing and automatically regulating an imposed. controlling back pressure adapted to restrict the travel of the piston and the other reciprocating parts sufficiently to prevent the building up of oscillations of dangerously high amplitude, and in which such back pressure is varied in proportion to the extent to which the travel of the reciprocating parts exceeds the desired maximum. 1,

Still another object is the provision of improved mounting means for supporting such a magnetically reciprocable compressor in a manresonance with the actuating current, of means for limiting the oscillating travel of the reciprocating parts against undesirably great amplitude without imposing additional back pressure upon the compressor except during those periods when such restriction is needed, and without varying the electrical efficiency ofthe magnetic driving means.

Still another object is the provision in such a compressor and motor unit of slightly modified form, of means for preventing oscillations of undesirably great amplitude and controlling the travel of the parts by automatic proportional variation of the electric current made effective to energize the electro-magnetic driving means Other objects and advantages will be apparent from the following description, wherein reference is made to the accompanying drawings illustrating preferred embodiments of my invention, and wherein similar reference numerals designate similar parts throughout the several views.

In the drawings:

Figure 1 is a diagrammatic view schematically illustrating a compressor and motor system in-. corporating the principles of this invention;

Figure 2 is a horizontal section, partly in plan, of a practical form of compressor and driving unit constructed in accordance with the invention;

Figure 3 is a vertical sectional view thereof taken substantially on the line 33 of Figure 2 and looking in the direction of the arrows;

Figure 4 is a fragmentary sectional view similar to oscillate toward and from the magnet, and

by their characteristics invest the armature with a natural period-of oscillation. The piston of a compressor K is shown connected to the armature. The springs F can so be sized that the natural period of oscillation of the armature is equal to the number of cycles of the current. In order to obtain the exact energization, one can either use an interrupter cutting one half wave of the current so that the back stroke of the armature is not braked,-or he armature itself might comnet lose its eflic'iency in course of time.

prise a permanent magnet which in the course of one cycle is once attracted and once repelled. However, both constructions are not very advantageous for the contacts would wear and the mag- In the present invention these disadvantages are eliminated by the arrangement of springs imposing on amplitude is obtained, or by changing the spring resistance.

Balancing to resonance can also be effected with the aid of the compressor piston. The manner in which this takes place is explained in detail'as follows: If a tightly sealing piston is forced into a completely closed cylinder which is filled with gas, the entrapped gas is compressed and exerts a force outwardly which increases with the distance that the piston is removed from its initialposition. If the piston is then released, it is returned to its initial position under the influence of the enclosed compressed gas. It acts therefore just like any other spring. The force which is exerted on the piston at any particular position thereof may easily be regulated to a desired magnitude by varying the pressure at the beginning of the inward movement of the piston or by varying the length of the cylinder or, more accurately, the distance of the initial position of the piston from the cylinder bottom. If, for example, the pressure in the cylinder is high at the beginning of the inward movement of the piston, then the pressure will rapidly increase upon further movement of the piston, and the force which is exerted outwardly is correspondingly increased. The same is true if the piston is close to the cylinder bottom at the beginning of its movement. In this case, too, the pressure will increase rapidly upon a slight inward movement and the piston will exert a large force outwardly. It is thus clear that a piston disposed in a gas filled cylinder acts likea spring, the strength of resilience of which can be accurately adjusted by suitably selecting the distance of .the piston from the cylinder bottom and by suitably selecting the pressure. A piston of this character may also be conveniently used to regulate the sprin iness needed for resonance. It has been found hat it is not necessary to supplement the steel springs of the present compressor with a special resilient piston, since the compressor piston itself involves a resilience, the temper of which depends directly upon the pressure. The springy action of the compressor piston arises in the following manner: With usual piston compressors, it is endeavored to have the piston move as closely to the cylinder cover as possible in order to expel the compressed gases as completely as possible. Inthe present compressor, the end positionof the piston is so adjusted that the piston does not move.

quite up to the cylinder cover so that, after completion of the expelling stroke a certain quantity of gas remains in the clearance space of the cylinder, which upon expansion forces the piston outwardly. The compressor piston thus acts as a spring and may therefore be used in es-. tablishing resonance. For this purpose, springs 1 of Fig. 1 of the oscillating system are selected so that they do not of themselves establish resonance, and the compressor when operating under no load is out of tune to such extent that an excessive amplitude-of vibration cannot occur. The clearance space of the piston is so designed that, when the operating pressure is reached and with it a complete damping of the oscillating system, the supplementary piston spring action due to the pressure now present, supplements the action of the steel springs to such extent that resonance is now completely established. By properly dimensioning the compressor cylinder relative'to the oscillating mass, it is possible to obtain a supplementary spring action adapted to harmonize or synchronize the system in a very simple manner.

The succeeding figures of drawings illustrate structures constituting practical working embodiments of the invention. In these references character 1 designates a box-like housing, preferably of metal and completely enclosed, (when the cover 2 is in place) save for the inlet 3 and outlet 4. The tightly fitting cover plate 2 is shown held in place by screws 5, and between it and the casing may be arranged a sealing gasket 6. One end of the housing carries a projecting boss portion 7 in which is formed a cylinder 8, within which is reciprocable a piston 9 adapted to be driven by an armature 10, to which it is articulated by means of a connecting rod 11. The connecting rod is preferably aflixed to both the piston and arma-- ture by means of ball and socket or other universal joints, as 12-12, which prevent imposition of lateral stresses upon piston and cylinder walls in event of any irregularities of movement of the armature. The armature is rigidly secured to the core portion 13, and the latter may be of the well known laminated and preferably soft iron, built up construction shown, although this is of course entirely optional. Preferably however the core portion 13 constitutes but a part of, preferably substantially half, the core of the solenoid 15 within which it slidably fits, the other half 14 of the core being of similar construction but fixed with respect to the winding and the housing 1. The abutting ends of the core sections 13-14 are arranged as close together as the reciprocation of the former will safely permit. Both the solenoid and the fixed core section are shown secured in position in the housing by means of a bracket 16, bolted to the floor of the housing as by screws 17 and arranged to support one end of each of the springs 18, which controllingly restrict movement of the armature and give it a natural period of oscillation, in the manner previously described. At its other end each spring is secured to and supports one end of the armature 10. In the constructions shown the springs 18 are axially outtumed and threaded at their ends, which are passed through suitable apertures (undesignated) in the bracket 16 and ar mature, and carry nuts 40 on both sides of each of the latter, by adjustment of which nuts the positioning of the armature, piston and movable core may be regulated. The springs are so tuned, and the masses of the reciprocatingparts so proportioned thereto that the natural frequency of the oscillating system comprising the springs, ar-

mature. piston and connecting parts is in tune with the frequency of the current by which the solenoid is to be energized. The solenoid may be electrically connected to binding post terminals 19, which as shown in Figure 2 project through the casing, but. are insulated therefrom as by bushings 20'.

a supporting plate 25 for the outlet valves.

The compressor inlet 3 may open directly into the casing 1, as shown, and valve ports 21 may be formed in the head of the piston which are normally closed on the compression stroke by a pair of flap valves formed of a single metallic strip, as 22, which may be of spring metal and secured to the piston by means of a screw-23. Between the head 24 and cylinder 8 is arranged The latter may be constructed similarly to the valves in the piston, and comprise ports 26 extending through the plate and normally closed during the reverse stroke of the piston by flap valves formed of a spring metal strip 27 centrally secured to the plate as by screw 28 and projecting over both of the ports 26.

From the head 24 an outlet passage 29 runs, through the casing, to an annular chamber 30 formed, as best shown in Figure 2, as an annular groove in one face of the casing body. This chamber is completed and normally closed by a diaphragm 31 held in place by the securing flange 32 of a supplementary cylindrical housing 33 for the compression spring 34, which urges the diaphragm against the edges of the groove 30 to yieldably close the annular chamber, and also closes the open end portion 35" of the passage 35 which forms a continuation of the outlet passage 29 and opensin the same face of the casing as does the annular groove 30, and inside the area bounded by the same, although it will be seen that communication between .the sections 29-35 of the outlet passage'is normally sealed by the diaphragm 31, save when .the compressor is generating sufficient pressure to unseat it. The spring '34 and diaphragm thus serveto prevent compressed fluid from flowing beyond the chamber 30 until a predetermined pressure has been attained, and so insure apredetermined minimum back pressure. The capacity of the outlet passage 29 and chamber 30 is so small that sufficient back pressure is built up to prevent the piston from striking the valve plate, and the building up of oscillations of dangerous amplitude, before the valve plate 25 as well as the diameter thereof are such, relative to the normal pressure, that the piston spring action which appears with increasing pressure brings about synchronization to resonance in the manner hereinbefore described. The machine will then assume the appearance shown in Fig. 3.

Preferably the casing is mounted in such manner that it is free to move laterally and oppositely under the successive reactive impulses im-. posed upon it each time the armature is driven in either direction by the springs and solenoid. It is shown mounted on springs 41, the main purpose of which is to permit free lateral movement of the housing, although they of course also prevent undue transference of vibrations to.

the base or other support on which the device is mounted, after the fashion of the cushioning devices commonly used under compressors. In place of such-springs, any other mounting permitting the casing free lateral movement might be used, as tracks upon which the casing might roll or slide, or rollers or wheels alone. It has been found that provision of this means whereby free reactive travel of the casing is possible produces very eflicient operation of the machine and full utilization of the forces generated.

In Figure 4 is shown a somewhat modified construction in which the electro-magnetic motor and compressor may be generally of like'construction however to those just described, like parts being designated by similar reference characters one hundred integers higher. In place of a pair of valves in the valve .plate 125, a single centrally located valve port 126 may be employed,

'normally closed during the down stroke of the piston by the spring leaf flap valve 127. Two valve ports 121 are provided in the piston in like manner tothe ports 21 in the first described embodiment, but the head of the screw 123 by which the valve member 122 is secured to the piston is of such size and so positioned as to slide within the port 126 as the piston approaches the end of its compression stroke, thereby closing or partially closing the space between the piston head and valve plate and trapping a quantity of the fluid being pumped therein to serve as a cushion.

' The outlet passage 129 extends from the head 124 to an annular chamber 130, similarly arranged to the chamber 30 previously described,

the outlet continuation 135 is normally yieldably closed by a diaphragm 131, pressed by the spring 134 against the wall separating the annular chamber 130 and the portion of the continuation 135, which opens in the same wall of theca'sing 101 as does the annular chamber 130, and inside the latter in like manner.

The spring 134 is relatively much weaker than analogous spring 34'of the previously described embodiment, however, and does not hold the diaphragm in outlet-closing position with force enough to create sufficient back pressure to prevent the building up of oscillations of unduly great amplitude by the reciprocating parts. The

spring housing 133 is hermetically sealed, as by means of the cap 136, and provided with an inlet passage 45 connected to the outlet 129 of the and communication between such chamber and pump. This passage is normally closed by a valve 46, which is held closed by the outlet pressure augmented by a spring 47. Valve 46 is adapted to be intermittently lifted by an adjustable stop 48 carried by the armature when and only when the latter moves farther in its oscillating travel than the-desired maximum amplitude. When this occurs the stop 48 contacts the valve stem 46', which extends into the inlet chamber of the housing to a point in proper proximity to the stop, (as shown in Figure 4). The stem 46 preferably fits tightly in the guide 49 to prevent leakage from the outlet to the inlet therealong. It will be seen that when the valve 46 is so intermittently opened by unduly extensive oscillations of the armature, fluid from the outlet under pressure is admitted to the chamber 133 behind the diaphragm 131 to augment the spring 134 and so force the diaphragm more tightly against its seat and close the outlet more firmly, thus building up greater back pressure in the chamber 130 and connected outlet, which such back pressure not only tends to dampen .the oscillations of the reciprocating parts, but acts as additional resilient resistance, thus de-tuning the system so that they die away in amplitude until stop 48 no longer lifts the valve 46, after which the pressure in chamber 133 is gradually relieved by escape of fluid therefrom through the connected bleeder passage 50 and bleeder valve 51 to the inlet or spring chamber of the housing. The

communication furnished through the bleeder valve and passage is of course insufiicien't, however, to prevent the building up of the augmenting pressure in the spring chamber when the valve 46 is being 0 ened in the manner described. It will be seen that by virtue of this arrangement, when the pump is operating under a properly proportioned load and the valve 46 remains closed, the back pressure in addition to that caused by the normal working of the compressor generated by the spring 134 is but slight, while 'if the work demanded by the compressor falls the choke, the winding of which is arranged in series with the solenoid 215 of the magnetic motor, as shown. A passage 229 connected to the outlet 235 of the pump extends to a chamber 230, one wall of which is formed by a flexible diaphragm 231 held in place by the bracket 232 which supports the choke coil. The diaphragm is connected to the movable core section 56, as by the link 57, and these parts are so arranged that when the diaphragm is relaxed the core is completely within the choke, and so the reactance of the latter is at its maximum; the eflect of course being to cut down the efficiency of the solenoid 215 to that extent. running, however, the pressure in chamber 230 is raised by reason of its connection with the pump outlet 235, and this pressure is sufficient under normal pump operation to move the diaphragm and so the core 56 suificiently so that the latter is out of the choke far enough to prevent its interfering materially with the current to the.

solenoid. The by-pass connection between the outlet-connected chamber 230 and the main inlet chamber of the casing 201 in which the armature is housed, is provided by .a passage 58 connecting these chambers but normally closed by a valve 246 yieldably held seated by the pressure in chamber 230 augmented by the force of spring 247. The valve stem 246 projects into the inlet chamber to a point adjacent the stop 248, which is so adjusted as to contact the same only when the armature stroke exceeds the desired maximum, at which time it intermittently lifts the valve 246, relieving the pressure in the chamber 230 and so allowing the diaphragm to relax and draw the core into the choke, cutting down the efliciency of the solenoid 215 and so reducing the power of the magnetic motor and the amplitude of the oscillations of the reciprocating parts. A metering valve as 59 in the passage 229 prevents the inflow of fluid to chamber 230 faster than the valve 246 can relieve the pressure when the latter is actuated by excessive oscillating travel of the armature.

It will be observed that in the embodiments When the compressor is' shown in Figures 2, 3' and 4, the efiiciency of the compressor is somewhat reduced (although but slightly in the embodiment shown in Figure 4) by the back pressure created by the diaphragm (31 131) in the outlet; and that in the embodiment shown in Figure 5 the electrical efllciency of the magnetic motor is likewise at times limited to prevent unduly extensive travel of the reciprocating parts. In Figure 6, however, is shown an embodiment in which neitherthe mechanical eificiency of the compressor nor the electrical eificiency of the magnetic motor are at any time interfered with, although effective means is provided for preventing oscillations of unduly great amplitude. This arrangement is such that upon the oscillations of the reciprocating parts exceeding the desired maximum, the oscillating system is thrown slightly out of resonance, and is held in that condition while the oscillations die to safe proportions, after which the resonant condition is restored and the operation may resume in the normal manner.

The entire unit is of course preferably so designed that the parts may oscillate in resonance when the compressor is under normal load. To throw the system out of resonance when the oscillations of the armature 310 reach undesirable proportions, a pair of springs 60 are provided, each attached at one end to the armature 310, as by screws 61, and at the other to a piston rod 62. Each piston rodcarries a piston 63 reciprocable' in an auxiliary cylinder 64 formed in the side of the casing 301 substantially in axial alignment with the central positioning of the spring 60.

Leather gaskets, as 65, 66, seal the chamber 67 beneath the piston, and to this chamber leads a passage 68 connected through a valve 346 to a source of fluid supply under pressure (not shown) which may comprise the outlet 335 of the pump, although no connection thereto is shown. The valvestem 346' extends into the inlet chamber of the casing to a point in such proximity to the armature-carried stop 348 that the latter intermittently lifts the valve whenever the travel of the armature becomes unduly extensive, thus admitting fluid under pressure to the chamber 6'7 to move the piston outwardly, stressing the spring 60- and so detuning the oscillating system as to throw it out of resonance. Preferably two such spring and piston assemblies are used, as shown, (although but one is broken away to. sectionally illustrate it in detail).

tem have died down to safe proportions as a result of the detuning of the oscillating system, the fluid admitted to the chamer 67 during actuation of the valve 346 may bleed through the valve and along the piston rod back to the inlet chamber,

and so permit the piston to move inwardly and the springs 60 to relax, when resonant oscillation can be reestablished.

14 While it will be apparent that the illustrated 5 embodiments of my invention herein disclosed are well calculated to adequately fulfill the objects and advantages primarily set forth, it is to be understood that the invention is susceptible to 5 variation, modification and change within the. spirit and scope of the subjoined claims.

What I claim is:

1. In combination with a source of pulsating electric current of substantially fixed frequency, a solenoid energizable by the same, an armature actuatable by the solenoid, a pump having a piston connected to the armature, means yieldably restraining the armature from movement and imparting a fixed natural period of oscillation thereto which. is substantially in tune with energization of the solenoid, and means preventing the oscillations of the armature from reaching an amplitude at which the armature might strike against any other part.

i 2, In combination with asourceof pulsating current of predetermined frequency, a solenoid energizable thereby, an oscillatable armature actuatable by the solenoid, a pump including a piston connected to the armature for simultaneous reciprocationv-c,resilient means imposing upon the armature a period of oscillation in tune with energization of the solenoid, and means for artificially increasing the back pressure of the pump to prevent reciprocable parts from oscillating at undesirably high amplitudes.

3. In combination with a source of pulsating current of predetermined frequency, a solenoid energizable thereby, an oscillatable armature actuatable by the solenoid, a pump including a piston connected to the armature for simultaneous reciprocation, and resilient means so yieldably restraining movement of the armature as to impose thereupon and uponthe piston a natural period of oscillation double the number of cycles of energizing current.

4. In combination with a source of electric current of predetermined frequency, an electromagnetic winding adapted to be energized thereby, an armature reciprocable by such electromagnet, a pump having an outlet and including a piston connected to the armature for simultaneous reciprocation, resilient means imposing upon the armature a period of oscillation in tune with energization of the solenoid, means for increasing the back pressure of the pump to prevent oscillav .tions of undesirably high amplitudes, including a pressure member yieldably obstructing the outlet, and means for increasing the tension with which such obstruction is maintained, comprising means for connecting the output of the pump to a chamber behind the pressure member, and means for opening said connecting means when oscillations of the reciprocating parts exceed a desired maximum.

5. In combination with a source of electric current of predetermined frequency, a solenoid winding emergizable thereby, ,an armature reciprocable by the solenoid, a pump having an outlet and a piston connected to the armature for simultaneous reciprocation, resilient means imposing upon the armature a period of oscillation in'tune with energization of the solenoid, means for increasing the back pressure of the pump to prevent oscillations of undesired amplitudes, including a spring-pressed member obstructing the outlet.

, 6. In combination with a source of electric current of predetermined frequency, a solenoid winding energizable thereby, an armature reciprocable by the solenoid, a pump having-an outlet and a piston connected to the armature for simultaneous reciprocation, resilient means im posing upon the armature a period ofoscillation for increasing the back pressure of the pump to prevent oscillations of undesired amplitudes, including a member adapted to obstruct the 'pump outlet and movable to offer more or less obstruction, pressure operable means for urging said member toward a position of greater obstruction, and means responsive to oscillations of the reciprocating parts of greater than a predetermined amplitude for rendering said fluid pressure means operative.

7. In combination with a source of electric current of predetermined frequency, a solenoid winding energizable thereby, an armature reciprocable by the solenoid, a pump having an outlet and a piston connected to the armature for simultaneous reciprocation, resilient means imposing upon the armature a period of oscillation in tune with energization of the solenoid,

means for increasing the back pressure 'of the pump to prevent oscillations of undesired amplitudes, including a member adapted to restrict the pump, outlet and movable toward and from reciprocable by the solenoid, a pumphaving an outlet and a piston connected to the armature for simultaneous reciprocation, resilient means impressing upon the armature a period of oscillation in tune with the energization of the solenoid, variable means for controllingly reducing the effective current by which the solenoid is energized, and means responsive to oscillations of the reciprocating parts of undesired amplitudes for actuating said current controlling means. a

9. In combination with a source of electric current of. predetermined frequency, a solenoid winding energizable thereby, an armature reciprocable by the solenoid, a pump having an outlet and a piston connected to the armature for simultaneous reciprocation, resilient means imposing upon the armature a period of oscillation in tune with energization of the solenoid, and

means for preventing oscillations of the reciproa cating parts of greater than a predetermined amplitude, comprising controllably variable means for impairing the current to the solenoid, pressure-responsive controlling means therefor connected to the pump outlet and normally held thereby in a position in which the former interferes to a minimum with the current to the solenoid, means operable in response to a predetermined degree of movement of a reciprocating part for relieving the pressure affecting said actuating means to resultantly vary the current energizing the solenoid to reduce the output thereof and so the severity of actuation of the armature.

10. In combination with a source'of pulsating electric current of predetermined frequency, a solenoid adapted to be energized thereby, an armature reciprocable by the solenoid, a pump having a piston connected to the solenoid for simultaneous reciprocation therewith, resilient means impressing uponv the reciprocating parts a period of oscillation in tune with energization of the solenoid, and means responsive to the amplitude of the reciprocations of the armature for varying said resilient means to detune the system to limit the amplitude of the oscillations.

11. In combination with a source of pulsating electric current of predetermined frequency, a solenoid energizable thereby, an armature actuatable by thesolenoid, a pump including a piston reciprocable by the armature, resilient means imposing upon the armature a natural frequency of oscillation in tune with energization to cooperate therewith and movable axially of the solenoid, means connecting the armature and said last named core section, resilient means connected with the armature providing a natural periodic oscillation frequency, and supplemental resilient means comprising a fluid compression chamber for opposing excessive oscillation amplitude.

13.'In an electromagnetic motor, a source of energy comprising an alternating electric current, electromagnetic driving means comprising a solenoid energized by said current, a core section fixed relatively to the solenoid and occupying only a part of the space therewithin, a reciprocable armature including a complementary core section forming'with the first mentioned section 'a substantially complete core but movable relatively to the solenoid and first section in resonance with said current.

14. In combination with a source of pulsating electric current of predetermined frequency, an

electromagnetic motor energizable thereby and including a reciprocable armature, a cylinder, a piston drivable by the motor, resilient means restraining movement of and imposing upon the armature a natural periodof oscillation approximately in tune with the impulses imparted to it, and means for controllingly imposing a back pressure upon the piston to vary the restraining forces acting thereupon and upon the armature and thereby tune the oscillating system 15. In combination in an electromagnetically driven reciprocating compressor, an electromagnet energized by periodically varying current, an armature actuated by said electromagnet, a. compressor comprising a cylinder and a piston, said piston being connected to said armature and actuated thereby, said piston and armature constituting together a reciprocating unit having said piston being connected to said armature and actuated thereby, said piston and armature con-' stituting together a reciprocating unit having resilient means impressing thereon an oscillatory frequency corresponding to the periodic variations of the current, said cylinder having a fiuid' outlet opening into a discharge conduit, means I excessive amplitude.

17. In combination in an electromagnetically driven reciprocating compressor, an electromagnet energized by periodically varying current, an armature actuated by said electromagnet, a compressor comprising a cylinder and a piston, said piston being connected to said armature and actuated thereby, said piston and armature constituting together a reciprocating unit having resilient means impressing thereon an oscillatory frequency corresponding to the periodic variations of the current, said resilient means comprising steel springs which impose on the system a natural period of oscillation which is so different from the energizing frequency that the amplitude remains less than a certain amount as long as the compressor has no back-pressure to overcome,' a resilient device comprising the piston and cylinder, and means for varying the resilience of said device, whereby the reciprocating unit is synchronized .to resonance with the periodically varying current.

18. In combination in an electromagnetically driven reciprocating compressor, an electromagnet energized by periodically varying current, an armature actuated by said electromagnet, a compressor comprising a cylinder and a piston, said piston being connected to said armature and actuated thereby, said piston and armature constituting together a reciprocating unit having resilient means impressing thereon an oscillatory frequency corresponding to the periodic variations of the current, said resilient means comprising steel springs, which impose on the system a natural period of oscillation which is so different from the energizing frequency that the amplitude remains less than a certain amount as long as the compressor has no back-pressure to overcome, a control cylinder, a cushion produced ,by gases enclosed in saidcontrol cylinder, said cylinder permitting thecushioning effect of the gases contained therein which, with complete counterpressure, is of such magnitude tha synchronization to resonance results.

' 19. Compressor drive comprising means forming an alternating magnetic field; an oscillating system under the influence of said field and having an oscillatory frequency in time with the field, a compressor, and a driving connection between said system and said compressor, said connection comprising a thrust rod and means providing for slight pivotal movement thereof.

20. In combination a compressor comprising a cylinder and a piston reciprocable in said cylinder, means for operating said compressor resonantly, a :base, and means supporting said compressor on said-base, said supporting means assuring maintenance of resonant operation of the compressor.

WILEELM KONIG.

' (Seal) 7 CERTIFICATE or CORRECTION.

Patent No. 1,978,866. October 30, 1934. 'WILHELM Kt'iNtG.

It is hereby certified that error appears in the printedspecification of the above numbered patent. requiring correction as follows: Page 6, line 40, claim 13, after the word ."current" and before the period insert the comma and words ,and a fluid compression device connected to the reciprocabie armature; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and-sealed this 12th day of February, A. D. 1935.

Leslie Frazer

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