US2943182A

US2943182A - Fluid stabilized arc mechanism

Info

Publication number: US2943182A
Application number: US707885A
Authority: US
Inventors: John W Prout; Noel J Sheehan; Jr James W Reid
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1958-01-09
Filing date: 1958-01-09
Publication date: 1960-06-28
Anticipated expiration: 1977-06-28

Description

June 1960 J. w. PROUT ETAL FLUID STABILIZED ARC MECHANISM Fiied Jan. 9, 1958 2 Sheets-Sheet 1 //V VEN TOR John W. Proui James W. Reid Noel J. Sheeho by ad-mu June 1960 J. w. PROUT ETAL I 2,943,182

FLUID STABILIZED ARC MECHANISM Filed Jan. 9, 1958 I 2 Sheets-Sheet 2 46 36 48 t 50 g I 34 66 g 78 as Q //V VE/V T01? John W. Prqu't James W. Reid Noel J. Sheehon by 4& 6 M

United States Patent FLUID STABILIZED ARC MECHANISM John W. Prout, Bridgeport, and Noel J. Sheehan, Philadelphia, Pa., and James W. Reid, Jr., Collingswood, N.J., assignors to General Electric Company, a corporation of New York Filed Jan. 9, 1958, Ser. No. 707,885

3 Claims. (Cl. 219-121) The present invention relates to a fluid stabilized arc mechanism and more particularly to a fluid stabilized arc mechanism capable of operating for extended periods of use with structural versatility and reliability, and with an extended range of use previously unrealized in devices of this general type.

In general, fluid stabilized arc mechanisms which deliver large thermal energy in the form of a high temperature plasma have been classified as research or development equipment because of structural limitations which prohibited the utilization of such equipment or apparatus for more than a few operational cycles. Further, because of the high temperatures developed by such electric arc and plasma producing devices in the super heated plasma working fluid, the structural components of such devices quickly deteriorated so that use of the stabilized are as a practical tool in such production areas as in welding, metal cutting, or the like was not feasible. Consequently, before a fluid stabilized arc mechanism could be used as a production device, the versatility of the structure would have to be increased to allow for the following: selective control of the arc temperature; greatly increased operational life of the device; reduced maintenance and operating costs; provision for a more stable and uniform arc; and more selective control over the plasma working fluid output.

Briefly, in order to provide a high temperature plasma for use in research, welding, metal spraying, cutting, testing, and the like, with an electric arc and plasma producing device, an electric arc is condensed or constricted into a smaller circular cross section than would ordinarily exist in an open arc typev device. This construction creates a very high temperature and by making one of the electrodes hollow, a super heated plasma working fluid is ejected therethrough which may be used in any desirable and suitable manner. The mass flow through the electrode nozzle and the composition of the plasma can be selectively changed by using different media to constriet the arc.

The present invention comprises a fluid stabilized arc mechanism having electric arc and plasma producing means generating an ultra high tempefilture plasma utilizing a fluid chamber to maintain temperatures at a safe level with respect to the immediate mechanism structure. Further, a replaceable vortex orifice plate is provided to permit the selective utilization of various size vortices to predeterminedly control the temperature of the are; for example, the smaller the vortex the more condensed or hotter the arc.

Electrode rod holding means are provided which permit a quick change of electrodes to allow the use of a wider selection of rod diameters for more versatility in the type and characteristic of the plasma working fluid generated. Accordingly, the present fluid stabilized arc mechanism with increased versatility and extended range of applicable uses can now be used more like a pro 'ice duction tool than a piece of research or development equipment, as presently considered.

An object of the present invention is the provision of a fluid stabilized arc mechanism which provides a high temperature plasma over an extended period of time without deleterious effects on the structure of the mechanism.

Another object is to provide a fluid stabilized arc mechanism having greater cooling capabilities and versatility of design so as to permit more control over the high temperature plasma output while reducing maintenance and operational costs.

A further object of the invention is the provision of a fluid stabilized arc mechanism capable of delivering a high temperature plasma by utilizing a fluid cooling system and by permitting the replacement of the electrode rod and the vortex orifice plate to provide selective control of the arc to obtain a desirable range of operational temperatures to increase the versatility and adaptability of the mechanism.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures there of and wherein:

Figure 1 is a sectional view of a preferred embodiment of the invention;

Figure 2 is a sectional view of the working and drain chambers of the preferred embodiment of Figure 1; and

Figure 3 is a sectional view of the swirl or are chamber of Figure 2 showing a suitable construction of one of the swirl holes.

Referring now to the drawings, there is illustrated a preferred embodiment 10 comprising an electric arc and plasma generator 12 suitably secured to a face plate 14 forming part of a suitable support, such as a stand 16, or the like, adapted to maintain the generator in a predetermined attitude dependent on the particular application.

The electric arc and plasma generator 12 is provided with a generally cylindrically shaped housing 18 of such suitable insulating material as Lucite, or the like. A top plate 20 is provided at one end of the housing, formed with an axial aperture 22 threadedly and replaceably supporting a nozzle retainer 24. A nozzle electrode 26 is replaceably supported within the nozzle retainer, so that, if desirable or deemed necessary, the electrode may be replaced to change nozzle size or to substitute therein a new and unused electrode.

An end closure plate 28 is provided on the housing 18, at the opposite end from the top plate 20, and formed with a suitable circular flange to sit in a suitable aperture on the face plate 14. The end plate is formed with an axial aperture 30 and a number of peripherally spaced drain apertures 32 provided with valve means, not shown, to selectively prevent the flow of any fluid therethrough. The housing 18 is formed with a drain chamber 34 between the end plate 28 and a baflle plate 36, which, in turn, provides the housing with a working chamber 38 between the baffle plate and the top plate 20. The working chamber is further divided into a fluid by controlling the amount of fluid remaining therein. The size of the generated arc in the swirl chamber, be tween the nozzle electrode 26 and a coaxially provided electrode rod 50 is determined by the size of the vortex which is a function of fluid passing through the axial aperture 48 from the swirl chamber which, in turn, determines the axial column void of fluid and available for the arc path between the electrodes. The cylindrical separating member 44 is provided with a plurality of swirl holes 51, as seen in Figures 2 and 3, suitably formed therein such as by drilling, or the like, so that a fluid medium, such as water or a gas from the fluid chamber, may be tangentially introduced into the swirl chamber to generate the desired vortex pattern therein. If desired, the swirl holes 51 may be replaced by a swirl slot of a suitable axial length to supply the desired vortex pattern. It will be obvious, that the size of the vortex and the resultant arc path can be selected by simply replacing the vortex plate 46 with another having the axial aperture size necessary to obtain the desired arc size.

The top plate 20 is provided with a plurality of radially extending fluid inlets 52 equally spaced about the circumference thereof, which direct fluid to a circular recess '53, formed on the interior surface of the top plate 20. Fluid introduced into the recess 53 enters the water chamber 40, and, further, serves to cool a large area of the top plate 20. The fluid inlets are conventionally connected to a fluid source, such as a water source, not shown, supply ing water under pressure to the fluid chamber 40 to maintain it continuously full while in operation, so that the pressure built-up therein will be suflicient to force water through the swirl holes. It should be understood, of course, that a variety of fluid media may be used within the fluid chamber, which would primarily depend upon the particular type of plasma working fluid desired which is a function of the intended application.

To facilitate construction of the housing 18, with the intended changeability of the various components therein, it is constructed of a number of cylindrical members, as shown in Figures 1 and 2, which rigidly maintain the baffle plate 36 in a predetermined location therein. The various components of the housing are retained in a unitary structure by a plurality of elongated stud members 54, provided with coacting nut members 56, which uniformly bias the housing components together to maintain a rigid structure. Suflicient sealing means are provided within the housing, at all component joints to prevent any fluid leakage therefrom. Also, a number of suitable electrical connections 58 are provided on one or more of the stud members and maintained thereon by the nut members 56, as shown in Figure 1. An electrical ground connection 59 is also provided secured on one of the stud members 54 and maintained thereon by the coacting nut member.

A hollow tubular member 60, suitably supporting the electrode 50 thereon, is axially slidable within the aperture 30 to predeterminedly control the spacing between the electrodes in the swirl chamber. A plurality of seals, such as chevron seals 62, or the like, are provided between the tubular member and the housing end plate 28 to prevent any leakage of fluid from the drain chamber 34. The tubular member is axially aligned with the nozzle electrode 26 and coaxial with the axial aperture 48 on the vortex plate 46, and is provided with an axial aperture 64 removably supporting at one end thereof a collet member 66. The collet, 66, of conventional design, replaceably supports therein the electrode rod 50 to permit the removal or substitution thereof. If necessary to accommodate electrode rods of diiferent diameters, the collet can be replaced with others of suitable bore sizes to permit such substitution.

The collet 66 is connected by threaded engagement, or the like, to one end of rod member 68 coaxially mounted within the aperture 64 of the tubular member. The rod 68 is resiliently mounted, at the opposite end from the collet, to the tubular member by a spring 70 biased between a first washer member 72, abutting an interior circular flange formed on the interior wall of the member 60, and a second washer member 74 adjustably maintained on the rod by a threaded nut 76. In this manner, the rod is axially slidable within the tubular member, and, in turn, will axially actuate the collet 66 and permit removal of the electrode rod therefrom. Obviously, any other suitable collet removing means may be employed, however, the utilized axially slidable rod 68 is compact and mechanically simple to maintain and operate.

The tubular member 60 is provided with a drain conduit 78, concentric with the axial aperture 64 but radially spaced therefrom to permit drainage of the fluid from the drain chamber through an outlet to a suitable drainage means not shown. Auxiliary drain outlets 32 are provided in the end plate 28, however, these outlets are provided with suitable valve means, not shown, to shut off any drainage therethrough. For example, if the fluid chamber 40 is filled with a gaseous medium the generator 12 will be pressurized and the auxiliary drain outlets will be shut olf so that the drainage of fluid will be all through the aperture 78.

The end of the tubular member 60, opposite from the collet end, is provided with a suitable frame structure 82 integrally fixed thereon for connecting an actuating mechanism, such as a servo feed or manually operative system, thereto for predetermined axial actuation of the electrode rod 50 in response to the voltage supplied to the

electrodes

26 and 50. In this manner, if desirable the electrode 50 can be axially adjusted to maintain the voltage constant. The actuating mechanism such as a hydraulic servo feed system 84, is operatively mounted on the support stand 16 in a conventional manner. For purposes of illustration, the system 84 is mounted on a supporting plate 86, which is an integral part of the support stand and axially spaced from the face plate 14 by a plurality of connecting structural members 87. The hydraulic servo feed system is provided with an axially actuated piston member 88 connected to the frame structure 82 to axially move the tubular member 60 and the rod electrode 50, mounted thereon, to selectively control the spacing between the coacting electrodes. As shown in Figure 1, an electrical connection 90 to the electrode 50 is suitably attached to the frame structure 82, which is conductively associated with the electrode rod.

In the operation of the preferred embodiment 10, the fluid is introduced into the circular recess 53, provided on the interior side of the top plate 20 and, in turn, into the fluid chamber, 40. This chamber is maintained full throughout the operational period of the electric arc and plasma generator 12, and enough fluid pressure is maintained to force the fluid through the swirl holes 51 located in the cylindrical separating member 44. The swirl holes introduce fluid into the swirl chamber 42 tangentially to the inner surface of the cylindrical member 44 so that the spinning action of the water creates a vertex in the center thereof. The diameter of this vortex is determined by the size of the aperture 48 in the replaceable vortex plate 46. Generally, the vortex in the swirl chamber is about to A; of an inch larger than the diameter of the rod electrode 50. When the are between

electrodes

26 and 50 is struck, the fluid in the swirl chamber condenses or constricts the arc, and part of the fluid boils away and leaves as part of the plasma which is ejected through the nozzle 26.

It will be obvious that fluid circulating from. the working chamber into the swirl chamber and, finally, into the drain chamber will cool the generator 12. Also, the recess 53 in the top plate 20 will provide greater cooling therein and increase the operational life thereof. If deemed desirable, fluid can be recirculated and a recirculation cycle established which can be pressurized. Further, since the carbon rod electrode 50 is consumed as the arc burns, it is continuously fed into the swirl chamber by the hydraulic servo feed system 84, or manually if desired. Through suitable and conventional electrical means, not shown, the voltage between the nozzle electrode 26 and the rod electrode 50 is sensed to regulate the action of the hydraulic servo feed system to feed the rod electrode into the swirl chamber at a rate which maintains the voltage constant. The are is extinguished by withdrawing the rod 50 or by letting it burnout when the servo feed system is stopped.

Briefly, the generator 12 is protected from the extremely high temperatures generated by the arc to increase the operational longevity of the fluid stabilized arc mechanism herein disclosed. Further, by the provision of the replaceable vortex plate 46, the size of the vortex produced within the swirl chamber can be controlled to obtain the desired temperature range in the plasma ejected through the nozzle electrode. By using the collet 66, to retain the rod electrode 50, within the hollow tubular member 60, the electrode may be quickly removed simply by actuating the servo feed system to completely withdraw the tubular member 60 from the generator 12, through the aperture 30. Next, the rod member 68 is axially actuated in the direction of the generator 12 so as to push the collet 66 out of the tubular member to thereby release the rod electrode 50 therefrom. The rod 68 can be actuated by having it contact a stopping structure, such as the supporting plate 86, or any other rigid structure in the axial path of the rod 68 when actuated by the servo feed system. Obviously, another rod electrode can be inserted into the collet and the rod 68 released to be biased by the spring 70 so as to reset the collet back into the tubular member 60.

The present invention discloses an electric arc and plasma generator 12 securely fixed to a support stand 16 with the rod electrode 50 axially actuated therein by the hydraulic servo feed system 84 in response to the voltage between the electrodes to maintain the voltage therebetween constant and, in turn, maintain the temperature range of the plasma working fluid substantially constant. In the preferred embodiment 10, the replaceable nozzle electrode 26 is a positively energized anode of graphite, or the like, and the electrode rod 50 is a negatively energized cathode, if desired the polarity of the electrodes can be reversed. A source of electrical power is applied across the electrodes to strike an electric arc therebetween and, to prevent it from spreading, the arc is confined within a small enough volume, to greatly increase its current density and temperature over that normally obtainable. The are is confined by introducing a suitable fluid, such as air, water, oxygen, or the like, into the swirl chamber at a substantially high velocity through the tangentially arranged swirl nozzles 51 to circulate as a high speed vortex about the arc.

Accordingly, the present invention discloses a fluid stabilized arc mechanism as a practical tool having increased versatility, increased operational life, and a more stable arc by maintaining a constant voltage through the use of a servo feed system 84. Also, maintenance and operating costs greatly reduced to further enhance the practicability and usefulness of the present fluid stabilized arc mechanism.

It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purposes of the disclosure which do not constitute departures from the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

l. A fluid stabilized arc mechanism comprising means forming a fluid chamber, a hollow cylindrical member concentrically mounted within the means forming the fluid chamber, the interior of said cylindrical member forming a swirl chamber, means forming a drain chamber coaxial with said swirl and fluid chambers, a nozzle electrode mounted in the end of the means forming said fluid chamber, a rod electrode axially movable within said drain and swirl chambers, means operatively connected to the fluid chamber for introducing fluid under pressure into said fluid chamber, swirl openings formed in the wall of said hollow cylindrical member to cause fluid within the swirl chamber to form a vortex, means for connecting a source of electrical power between the rod and nozzle electrodes, and servo means for axially actuating the rod electrode in response to the voltage between the nozzle and rod electrodes.

2. A fluid stabilized arc mechanism having a swirl chamber, a fluid chamber concentrically mounted with respect to said swirl chamber, swirl holes tangentially formed on the wall of said swirl chamber to interconnect said fluid chamber therewith, a replaceable nozzle electrode at one end of said swirl chamber, a variable vortex orifice at the other end of said swirl chamber, a rod electrode slidable through said variable vortex orifice and predeterminedly spaced axially from said replaceable nozzle electrode, means for allowing fluid into said fluid chamber through said swirl holes under pressure to generate a vortex therein, wherein the vortex is a function of the diameter of the variable vortex orifice, automatic feed means coupled to said rod electrode for axial actuation in response to a voltage between the electrodes, and electrical power means coupled to said electrodes to generate a voltage therebetween.

3. A fluid stabilized arc mechanism comprising an electric are and plasma generator having a working chamber and a drain chamber, a baflie plate separating said working and drain chambers, a replaceable vortex plate operatively associated with said baflie plate and having an axial aperture therein, said working chamber having a fluid chamber and a swirl chamber coaxially mounted therein, a cylindrical member mounted within said working chamber and separating said fluid and swirl chambers, fluid inlet means operatively coupled to said fluid chamber to supply fluid under pressure thereto, a plurality of tangential swirl holes longitudinally located on said cylindrical member to pass fluid into said swirl chamber to generate a vortex therein as a function of the diameter of said axial aperture in said vortex plate, a replaceable nozzle electrode at one end of said swirl chamber, a rod electrode axially slidable through said axial aperture and axially spaced from said nozzle electrode in said swirl chamber, tubular means releasably supporting said rod electrode coaxially within said generator, and rod electrode releasing means operatively coupled to said tubular means to predeterminedly release said rod electrode therefrom, electrical power means coupled to said electrodes for generating an arc therebetween, and servo feed means operatively coupled to said tubular means for slidably actuating said rod electrode in response to the voltage across said axially spaced electrodes.

References Cited in the file of this patent UNITED STATES PATENTS 2,360,160 Pickhaver Oct. 10, 1944 2,768,279 Rava Oct. 23, 1956 2,770,708 Briggs Nov. 13, 1956 OTHER REFERENCES Zeitschrift fiir Physik, Bd. 138, 8-170-182-1954.