US 3004189 A
Description (OCR text may contain errors)
ma.. s@ x Z am x 3A 54 5 d m Q i .M M 2 ^f... M 5 ww/ mi., .I1 mw Q/ luFmw S u H mms... u 7E 7 W r 4 7 A Mmmm @w VE@ /2 www 5 H GMM... w www n@ w um w H/ I 5 w n e 4 T... E W M w COMBINATION AUTbMTic-STARTING ELEC- 'rRrLcAEL PLASMA TORCH AND GAS sHUroFF yva v Gabriel M. Giannini, Newport Beach, Calif., assigner to Plasmadyne Corporation, Santa Ana, Calif., a corporation of California Filed Oct. 5, 1959, Ser. No. 844,243 12 Claims.v (Cl. 315,-111) This invention relates to a combination electrical plasma-jet torch and shutoff valve. v
An object of the present invention is to provide a remote-operated combination plasma vtorch and shutoi valve which may be employed to control the attitude of a satellite and which is characterized by high efficiency and extreme gas economy.
A further object is to provide satellite-propulsion appag ratus ofthe type in which a multiplicity of bursts of power are employed to maintain the vessel oriented in space, said apparatus being adapted to prevent or minimize loss of propellant at the beginning and end of each power burst and thereby maintain the increased etiiciency Vof the arc-jet propulsion system as compared to otherk propulsion systems.
A further object is to provide an electrical plasmaiet torch and duid shutoff valve wherein 'the arc is initiated automatically and simultaneously with crackingv of rthe valve, and is extinguished each time the valve is closed.
These and other objects and advantages of tion will be more fully set forth in the following specithe invenblock flow of gas through the nozzle as illustrated in FIG- The remainder of element 11 is illustrated as being cylindrical, the diameter of the cylinder being shown as greater than the largest diameter of nozzle wall por? URE l.
tion 1S. Element 11 may be formed entirely of a refractory metal such as tungsten, or may be provided with-a tungsten layer adjacent wall 22.
The means 12 for actuating element 11 between closed and open positions is illustrated to comprise a solenoid 23 which is fixedly mounted in a housing 24 in spaced co-l axlal relationship relative to nozzle electrode 10. A core Y or armature 26, formed of a magnetizable material such as soft iron, is movably mounted in the central opening in` solenoid 23. The core 26 is iixedly connected at its forward end to electrode and valve plug element 11, and extends loosely, at its central portion, through an opening 27 in the forward wall of housing 24. When the valve l plug 11 is seated on nozzle wall 18, as shown in FIGURE 1, the rear end of armature 26 is spaced forwardly from the rear wall of housing 24. It is therefore possible by energizingr the solenoid 23, to eiiect retraction ofthe core and' of element 11 to the positions shown in FIGURE 2, I the rear end ofthe core then seating on the rear housing"y wall which acts as a stop.
ln addition to thersolenoid 23 and core 26, the actuating means 12 comprises a helical compression spring 28 the forward end of which is seated against the shoulder formed at the rear surface of plug 11 radially outwardly iication and claims, considered in connectionwith the I attached drawing to which they relate.
y1n the drawing:
FIGURE l is a schematic longitudinal sectional view illustrating the combination plasma-jet torch and gasy shutoff valve in closed or inoperative condition;
FIGURE 2 is a view corresponding to FIGURE l but illustrating the apparatus in operative or open condition; and
FlGURE 3 is a fragmentary View of the forward end portion of the back electrode, taken from ystation 3 3 indicated in FIGURE 2. s
Referring to the drawing', the apparatus is schematically, represented as comprising a combination nozzle electrode and valve seat 10, a combination back electrode and valve plug 11, remote-operated means 12 to eiect actuation of element 11 between closed and open posil tions, means 13 toy conduct gas to the vicinity of nozzle electrode 10 for tlow therethrough in the form of highfrustoconical and forwardly divergent, and defines the dischargeportion of the nozzle. The rearwardly-divergent inner portion 18 of the wall of nozzle opening 16 is also frustoconical and forms both the inlet portion of the nozzle and the seat for valve plug 11. The element 1t! should be formed, at least adjacent nozzle opening 16, of a refractory metal such as tungsten. The remainder of the nozzle electrode may be formed of cooper or thel'like, and may incorporate a cooling chamber 19 through which water is circulated by means of conduits 21.
The combination backy electrode and valve plug 11 has a conical forward wall 22 the angle of which is the same as that of the nozzle wall portion 18, so that thewall 22 will seat in surface engagement with wall portion 18 to of the core. The rear end of spring 28 seats against a ring 29 which is ixedly secured to the forward surface v Ring 29 is of housing 24 around opening 27 therein. formed of copper or the like, and spring 28 isforrned of a spring metal having substantial conductance. f The actuating means for the combination electrode an valve plug 11 further comprises uid pressure present in an annular chamber 31 defined by a tubular insulating member 32. sealing relationship, coaxially between the peripheral portions of nozzle electrode 10 and housing 24.
The means 13 to introduce gas to the vicinity of nozzle opening 16 is illustrated to comprise a bore formed axially through the armature 26 and through the rear pertion of element 11. The forward end of the bore com-r municateswith a plurality of passages 33 which extend to plug wall 22 at about the mid-portion of nozzle wall portion 18 when the valve plug is in seated position as` shown in FIGURE l. It follows that when the plug 11 is maintained seated by the combined operation of spring 28 and the uid pressure in chamber 31, passages 33 are blocked. When the plug is shifted to its open or FIGURE 2 position, the rear end of the bore in core 26 registers with aconduit 34 leading to a suitable source 36 of gas or propellant under pressure. Thus, gas may dow from source36 through the bore in core 26 and plug 11 to the radial passages 33, from whence it flows outwardly through nozzle opening 16 vin. the form of the plasma jet indicated generally at 37.
form of the high-,velocity high-temperature plasma jet 37 because of the operation of current-supply means 14 to strike and maintain an arc, between surface 22 of electrode 11 and the wall of nozzle opening 16, at substantially all times when the valve isy open as shown in FIGURE 2. Current source 14 is illustrated as connected through a lead 38 to one terminal of solenoid 23, the other terminal of such solenoid being connected through a lead 39 to the current-conducting ring 29. Since ring 29 is in electrical contact with current-conducting spring 28,r and since spring 28 is in contact with back electrode 11, cur-` rent is delivered to such electrode and may flow to nozzle electrode 10 either in the form of an arc (when the valve Patented Oct. 1o, 1961 Insulator 32 is iixedly secured, in suitable a is open) or directly (when the valve is closed). Nozzle electrode is connected through a lead 41 to the remaining terminal of source 14, so that a series circuit is formed through solenoid 23 and the electrodes 10 and 11. A switch 43 is interposed in leadl 38 to permit remote control of the, torch apparatus.
Operation In the operation of the combination electrical plasmajet torch and gas shutoff valve, it will first be assumed that switch 43 is open. Solenoid 23 is thus in de-energized condition, so that the spring bias exerted by spring 2S and the duid pressure present in chamber 21 combine to maintain the valve plug 11 seated on surface 18 as shown in FIGURE l. No iiuid may escape from gas source 36 through conduit 34, opening 27, chamber 31 and nozzle opening 16 since such escape is blocked by the engagement of cooperating surfaces 18 and 22. Also, no iiuid may escape through conduit 34, bore 13, and passages 33 to nozzle opening 16 since the passages 33 are blocked by surface 13. l
Upon closing of switch 43, solenoid 23 is energized and is adapted to exert sufficient force on the magnetizable core 26 to shiftv surface 22 of the back electrode out of contact with surface 18 of the nozzle. Such cracking of the valve elects two functions simultaneously, namely permitting escape of gas through nozzle opening 16 and also drawing of an arc between back electrode 11 and the nozzle electrode in the vicinity of opening 16. Continued rearward movement of plug 11 causes such arc to grow progressively longer, and also creates a progressively greater cross-sectional area through which gas may escape out the nozzle opening, until the core 26 engages the housing wall as indicated in FIGURE 2. l
The above-described simultaneous cracking of the valve and drawing of the arc cause immediate formation of the plasma jet 37 which escapes at high velocity through the nozzle opening. The result is a substantial reaction forcewhich may be employed for propulsion of a satellite or the like. The quantity of escaping plasma is greater when the valve is fully open, as shown in FIGURE 2, but it is emphasized that plasma is formed substantially immediately upon cracking of the valve so that little or no gas escapes in the form of low-temperature gas as distinguished from high-temperature high-velocity plasma. It is to be understood that the electric arc greatly increases the velocity of the escaping gas, to result in a reaction force greater than would be exerted if no arc were present.
Upon re-opening of switch 43, solenoid 23 is immediately de-energized and the are is extinguished, so that the spring 23 and the force exerted by the flowing gas combine to effect seating of plug 11 on the valve seat portion on the nozzle, as shown in FIGURE 1. A small amount of gas may escape in the form of gas (as distinguished from plasma) during the short time interval required for the valve to return to seated position. Such escape of relatively cool gas, however, performs the function of effecting substantial immediate cooling of the opposed conical surfaces 18 and 22 to thereby minimize the possibility that sueh surfaces may stick and Vimpede subsequent re-.opening of the valve.
It is a feature of the invention that gas flows between the arcing portions of the nozzle and back electrode during all times when an arc is maintained therebetween, so that the arcing electrode portions are cooled by the gas to minimize deterioration thereof. It is therefore possible in many instances to eliminate the coolant `chamber 19.
It is pointed out that gas liowing against the forward end of passage 13 provides a force tending to effect ciosing of the valve plug against seat 18. Also, the gas pressure in chamber 31 acts against the shoulder formed on plug 11 adjacent spring 28, thereby tending to maintain the valve closed.
The described apparatus is readily operated by remote control, does not require special automatic starting means,
and effects wastage of little or no gas from source 36 even during intervals when the valve is opening or closing. It follows that the apparatus may be stopped and started frequently, as required to maintain the attitude of the satellite, without substantially reducing eiciency and wasting the gas in source 36.
Various embodiments of the present invention, in addition to what has been illustrated and described in detail, may be employed without departing from the scope of the accompanying claims.
I claim: Y
1. In an electrical plasma-jet torch, nozzle means through which gas may be discharged, electrode means to maintain an electric arc in the vicinity of said nozzle means to thereby heat the gas discharging through said nozzle means and result in formation of a high-temperature high-velocity plasma jet, and means to effect substantially simultaneous initiation of said electric arc and of gas iiow through said nozzle means.
2. In an electrical plasma-jet torch, nozzle means having a nozzle opening therein and having an electrode por-` tion adjacent said nozzle opening, back electrode means having an electrode portion normally in contact with said electrode portion of said nozzle means, means to effect tiow of current through said electrode portion of said nozzle means and back electrode means, means to effect movement of said back electrode means away from said nozzle means to thereby separate said electrode portions thereof and draw an arc between said electrode portions, and means to effect flow of gas adjacent said arc and out said nozzle opening in the form of high-velocity plasma, said last-named means including means responsive to said movement of said back electrode means to control said ow of gas.
3. In an electrical plasma-jet torch, nozzle means having a nozzle opening therein, electrodev means adapted to maintain an electric arc in the vicinity of said nozzle opening, and combination gas-control and arc-initiating means to effect relative movemet between said electrode means and thereby initiate an arc therebetween and also to effect flow of gas through said nozzle opening whereby said gas is heated by said arc and discharged in the form of hightemperature plasma.
4. An electrical plasma-jet torch, which comprises la first metal element including a combination nozzle electrode and valve seat, said valve seat being around the nozzle opening in said nozzle electrode, a second metal element including a combination back electrode and valve plug, said valve plug being adapted to seat on said valve seat and block flow of gas through said nozzle opening, means to impress a voltage on said first and second elements whereby current flows therebetween through the" engaged valve plug and valve seat, means to deliver gas under pressure-to the vicinity of said first and second elements, and actuation means to shift said second element away from said first element to thereby'permit liow of gas between said valve plug and valve seat and simultaneously draw an arc between said valve plug and valve ,set whereby said gas is converted into plasma and flows at high velocity through said nozzle opening.
5. An electrical plasma-jet torch, which comprises a iirst element including a combination nozzle electrode and valve seat, said valve seat being around the nozzle opening in said nozzle electrode, a second element including a combination back electrode and valve plug, said valve plug being adapted to seat o n said valve seat'and block flow of gas through said nozzle opening, means to impress a voltage across said rst and second elements whereb)I current flows therebetween through the engaged valve plug and valve seat, means to deliver gas under pressure to the vicinity of said iirst and second elements, and actuation means to shift said second element away from said iirst element to thereby permit liow `of gas between said valve plug and valve seat and simultaneously draw an arc therebetween, said last-named means comprising a magnetizable element associated with said second element and remote-controlled solenoid means to eiect shifting of said magnetizable element and thus of said second element.
6. The invention as claimed in claim 5, in which said means to impress a voltage across said lrstand second elements includes means to create a series electrical circuit through said solenoid whereby said solenoid is energized substantially simultaneously with impressing of said voltage and drawing of the are between said valve plug and seat,
7. The invention as claimed in claim 5, in which means are provided to maintain said second element seated on said rst element at substantially all times except during energization of said solenoid.
8. The invention as claimed in claim 7, in which said means includes means to employ the pressure of said gas to maintain said second element in seated position.
9. A combination automatic-starting electrical plasma torch and gas shutoff valve, which comprises a metal nozzle electrode having a nozzle opening therein, said nozzle electrode being shaped as a valve seat around said opening, a metal back electrode adapted to seat sealingly on said valve seat, passage means formed through said back electrode to deliver gas to the surface of said back electrode which seats on said valve seat whereby ow of gas through said passage means is blocked by said valve seat when said back electrode is seated thereon, means to deliver gas to said passage means, means to effect ow of current through saidr nozzle and back electrodes, and actuating means to shift said back electrode away `from said nozzle electrode to thereby permit ow of gas out said passage means and thence out said nozzle opening and simultaneously draw an arc between said nozzle and said back electrodes to eiect heating of said gas and formation of high-temperature high-velocity plasma.
10. The invention as claimed in claim 9, in which said last-named means comprises solenoid means'associated with said back electrode, and in which means responsive to the pressure of the gas delivered to said passage means is provided to aid in seating of said back electrode on said nozzle electrode upon release of said solenoid means.
:11. The invention as claimed in claim 9, in which current-conducting spring means are provided to maintain said back electrode in seated condition on said nozzle electrode, in which said actuating means includes solenoid means to etect shifting of said back electrode away from said nozzle electrode against the bias of said spring means, and in which said current-flow means includes means to complete a series circuit from said solenoid means through said spring means to said back electrode.
12. The invention as claimed in claim 9, in which means are provided to eiect ow of gas not only through said passage means but also externally around said back electrode. f f
References Cited in the tile of this patent UNITED STATES PATENTS