US3479471A

US3479471A - Electric plasma moving current collector

Info

Publication number: US3479471A
Application number: US679685A
Authority: US
Inventors: Russell R Smith; George Sonnemann
Original assignee: United Aircraft Corp
Current assignee: Raytheon Technologies Corp
Priority date: 1967-11-01
Filing date: 1967-11-01
Publication date: 1969-11-18
Anticipated expiration: 1986-11-18
Also published as: JPS4914562B1

Description

R. SMITH ET AL 3,479,471

ELECTRIC PLASMA MOVING CURRENT COLLECTOR 3 Sheets-Sheet 1 Nov. 18, 1969 Filed Nov. 1, 1967 lsavsoRi CTRL POWER 52 SOURCE KKJ KKJ) FIG. 3

INVENTORS RUSSELL R. SMITH GEORGE SONNEMANN ATTORNEY Nov. 18, 1969 3,479,471

ELECTRIC PLASMA MOVING CURRENT COLLECTOR Filed Nov. 1, 1967 3 Sheets-Sheet 2 NOV. 18, 1969 R R SMlTH EI'AL 3,479,471

ELECTRIC PLASMA MOVING CURRENT COLLECTOR Filed Nov. 1, 1967 3 Sheets-Sheet 5 M V Z8 N sgw sgws 1| VIIIIIIIIIIIIIIIIIIIIA FIG. /4 FIG. /2

United States US. Cl. 19145 8 Claims ABSTRACT OF THE DISCLOSURE Physical contact between the catenary wire and the shoe for conducting electricity to a moving vehicle is replaced by a conducting plasma across an intentionally maintained gap. The vehicle-mounted electrode may com prise an oscillating or endlessly cycling belt or track or a rotary disc having an axis perpendicular to the catenary wire. To rapidly displace, wobble or oscillate the point on the wire at which the plasma impinges so as to prevent erosion while the vehicle is stationary, surface projections or raised patterns are provided on the vehiclemounted electrode so as to attract the plasma to different points; alternatively, magnetic fields may be used to force the plasma to oscillate rapidly between different positions on the catenary wire. A high frequency coil in combination with low ionization electrodes may provide a starting avalanche for initiating 'D.C. operation, as well as reinitiating successive cycles of AC. operaton. Isotopes may be used to enhance the conductivity of the plasma.

BACKGROUND OF THE INVENTION Field of invention This invention relates to a contactless electric conducting plasma connection for current collection between a stationary transmission line or conductor and a moving vehicle, and more particularly to means for implementing the same.

Description of the prior art 'Electrical connections between a stationary wire and a moving vehicle known in the prior art are limited in operating range by several major problems. These are all basically mechanical sliding contact types. In order to maintain reasonable losses at the point of contact, mechanical systems require a large normal force between the shoe of the vehicle and the catenary wire. This large normal force produces an abnormally high amount of friction, which results in excessive wear and heating of the shoe. Even at moderate vehicle speeds, mechanical imperfections in the system result in bounce and intermittent mechanical separation producing uncontrolled erosive arcing which causes severe degradation in the mechanical components of the system, leading to high replacement costs, and in some cases catastrophic failure while in operation. An additional problem relates to the normal force required to maintain a shoe in contact with the catenary wire. This creates mechanical oscillations along the length of the wire behind the point of contact, which add further difiiculty in maintaining a good sliding contact between the shoe and the transmission line. Furthermore, the speed at which a shoe can silde along a transmission line is definitely limited, and, therefore, can impose a maximum operating speed on a moving vehicle. The maximum speed may relate to the speed at which the mechanics of the system can function, or may result from limitations in power which can be transferred by Patented Nov. 18, 1969 "ice SUMMARY OF INVENTION The object of the present invention is to provide means for utilizing an electrical plasma to conduct current between a catenary wire and a moving vehicle, or between any other relatively moving parts or objects.

According to the present invention, plasma flow in the cold cathode field emission .mode is enhanced and thermionic erosive arcing is reduced to a minimum in electrodes upon which a high current carrying plasma impinges are overcome by provision of surface area moving transversely of the wire on the 'vehicle mounted electrode. In accordance further with the present invention, problems relating to the impingement of plasma on a catenary wire while the vehicle is at rest are overcome by relative elec= trode surface displacements and by magnetic means to alter the point of plasma impingement on the wire and on the shoe electrode. In accordance still further with the present invention, the initiation and conductivity of the plasma is enhancedby use of radioisotope materials embedded in the electrode. Still another aspect of the invention provides for the starting or restarting of an electrical discharge by means of a high voltage coil in combination with a high potential gradient electrode for an easy discharge.

The foregoing and other objects, features and advantages of the present invention will become more apparent in the light of the following detailed description of pre= ferred embodiments thereof as illustrated in the accom panying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a semipictorial diagram of a moving vehicle system incorporating-1a power source applied to the vehicle through a catenary wire and a pantograph-mounted electrode by means of'plasma.

FIG. 2 is a simplified front elevation of a moving belt electrode for use in the embodiment of FIG. 1.

FIG. 3 is a plan view of the embodiment of FIG. 2.

FIG. 4 is a side elevation view of an alternative electrode for use in the system of FIG. 1. 1

FIG. 5 is a plan view of the embodiment of FIG. 4.

FIG. 6 is a plan view of a modification of the embodiment of FIG. 3.

FIG. 7 is a side elevation view of a modification of the embodiment of FIG. 4.

FIG. 8 is a plan view of the embodiment of FIG. 7. FIG. 9 is a front elevation, partially sectioned view of another embodiment of an electrode for the system of FIG. 1.

FIG. -10 is a side elevation view of of FIG. 9. 6

FIG. 11 is a side elevation view of still another embodiment of an electrode for use in the system of FIG. 1. FIG. 12 is a front elevation view of the embodiment of FIG. 11. a

FIG. 13 is a sectional view of isotope-embedded mate= rial in accordance with the present invention.

FIG. 14 is a section view of an isotope-coated material in accordance with the present invention.

the embodiment 3 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, a moving vehicle, such as a train 20, may include a pantograph 22 which supports an electrode 24. The electrode 24 carries electrical current delivered by a catenary wire 26 through a plasma 28 (orelectrical breakdown or avalanche). The catenary 'wire or transmission line 26 may be supported by a messenger wire 30 as is known in the art. In order to drive the vehicle, a remote external stationary power source 32 is normally connected between the catenary wire 26 and a return conductor such as grounded rails 34. The pantograph 22 may include a servo-positioning system 36 for coarse height adjustments, such as the variation between the height of the wire 26 when under a low bridge, or in a tunnel compared with normal height when outside of a tunnel.

The present invention relates to improvements in the electrode 24 and in the use of a plasma 28 operating in a non-destructive cold cathode emission mode rather than the more common erosive hot thermionic emission mode.

In FIGS. 2 and 3 there is shown a rear and top view, respectively, of one embodiment of the present invention in which the electrode 24 comprises an electrically conducting belt or web 36 disposed for longitudinal belt motion (lateral with respect to length of catenary wire 26) on a pair of driving wheels or drums 38, each of which includes a slip ring 40- to which electrical contact may be The belt 36 may be driven in an oscillatory fashion, or in a continuous, unilateral fashion by means of a motor 44, a drive chain or belt (or oscillating type linkage) 46, and

suitable sprockets or

pulleys

48, 50. The drive wheels or drums (or linkage) 38 may be suitably journalled for rotation, here illustrated merely as shafts 52 for simplicity. Current in the catenary wire 26 is passed through the plasma 28 onto an ever changing portion of the belt 36, and transferred through the belt 36 to the drive mechanism therefor, whence the brushes 42 may collect current from slip rings 40 or other suitable surfaces and pass the current down the p'antograph to the train 20. Inorder to carry current from the electrode 24 (FIG. 1) to the train 20, each of the joints of the pantograph may be bypassed with a heavy conducting wire or flexible cable jumper, whereby current. flows through the bypass wires and through the pantograph structure to the train 20. Or, if desired, one or more separate current conducting cables may be provided from the electrode 24 to proper power circuits in the train 20.

The belt or web36 may be suitably supported by a bed or plate 54, which in turn may be disposed in any well known fashion to 'the top of the pantograph 22. In the embodiment of FIGS. 2 and 3, the folded length of the '30 made by brush assemblies 42, or other sliding contacts' 60 which prevents plasma from impinging upon the central areas of the disc 56,.thereby insuring that the plasma will impinge on the surface of thedisc 56 which is near the periphery thereof, thereby to continuously present fresh cool surfaces at point of arc impingement on disc and to provide maximum cooling of the metal upon which the plasma impinges. The shaft 58 may be suitably driven by a motor 62 at any appropriate sufficiently rapid speed. A slip ring 64 or other suitable surface may be provided in combination with brushes 66 or other suitable current collector so as to conduct the current either through the pantograph 22 or directly to the train 20 via a suitable current carrying cable. The electrode assembly of FIGS. 4 and 5 may be suitably disposed on the pantograph 22 in a y well known fashion.

It may be noticed that in the embodiments of FIGS. 2 and 3 and of FIGS. 4 and 5, the metal or conducting surface of the electrode 24 moves transversely of the catenary wire 26. In order to prevent overheating and depletion of the catenary wire 26 when the vehicle is at rest or moving very slowly under power, the embodiments of FIGS. 2 and 3 may be modified as shown in FIG. 6, and the embodiment of FIGS. 4 and 5 may be modified as shown in FIGS. 7 and 8.

In FIG. 6, the belt or web 36 is provided with a raised conductive portion 68 which is therefore closer to the catenary wire 26 than the remainder of the belt or web 36, and therefore the plasma will impinge on this portion of the belt. This in turn will cause the point of plasma impingement on the catenary wire 26 to vary between a point indicated in FIG. 6 by reference 70 and a point indicated by reference 72. Thus the raised portion 68 causes the impingement'of the plasma on the wire 26 to oscillate rapidly back and forth rather than stand inone place, when the vehicle is at rest.

,Similarly, the embodiment of FIGS. 7 and 8 includes scalloping whichprovides low portions 74, at the periphery interspersed with high portions 76 at the periphery.

belt 36 may be chosen to suit the particular system being distance between the wire 26 and the electrode 24 to a' control 27 for the servo 36. The sens0r'25 may comprise a plurality of high intensity lights 29 directed toward a plurality of photocells 31, as seen in FIG. 2 (eliminated from FIG. 3 for simplicity). The sensor elements 29, 31 are mounted forwardly of the electrode 24 on suitable extensions of the supporting frame therefor.

In the embodiment of FIGS. 4 and 5, a disc 56 rotates on a shaft 58 which is perpendicular to the catenary wire 26. The disc 56 is fitted with a disc of dielectric material An alternative construction may use simply the variable position raised portions 68 of FIG. 6, suitably adapted near the periphery of the disc 56' in FIGS. 7 and 8 The varying surface of the disc 56 will cause the plasma 28 i to oscillate between the positions shown on FIG. 7, the plasma impinging (as shown in full line) at the periphery of the disc 56 when a high point 76 passes beneath the catenary 26, and impinging adjacent to the dielectric disc 60 as shown dotted at 28 when a low point 74 passes beneath the catenary.

A different method for insuring that the plasma impinges on different portions of the catenary 26 when the vehicle is moving slowly or at rest is illustrated in FIGS. 9 and 10. Therein, a. plurality of

magnets

80, 82, 84 are each provided with coils 86, suitably wound and energized in accordance with the teachings of the prior art (not shown) so as to provide alternate magnetic poles as illustratedin FIG. 9. With the magnet 82 centered beneath the catenary 26'as shown in FIG. 9, the plasma will be forced forwardly as indicated at 28' in FIG. 10. However, if the train moves to the right or left (as seen in FIG. 9), so as to fall between magnet coil 80 and magnet coil 82 or between magnet coil 82, and magnet coil 84, then the direction of flux through which the plasma passes will reverse and the plasma will be pushed backwardly as shown at 28 in FIG. 10. In operation, however, energization of the magnets is preferably made alternating, so that as the vehicle is at rest, and therefore there is a static positioning between the' catenary 26 and the magnets 80-84, the magnetic field which is estab- 'wir e 26. The assembly illustrated in FIGS. 9 and 10 need lnot include any form of moving electrode, such as that illustrated in the embodiments of FIGS. 2 and 3,

since the magnetic field moves the plasma with respect to the electrode.

The embodiments of FIGS. 6-10 thereby provide for movement of the plasma along the catenary even while the vehicle is at rest.

In FIGS. 11 and 12 is shown an additional embodiment of the present invention, which is illustrated as including the embodiment of FIGS 2 and 3 with an additional apparatus for the initiation of an avalanche .or discharge between the catenary 26 and the electrode belt or web 36. Therein, ail RF coil (such as a Tesla coil) or highvoltage A.C. coil 85 is connected to a sefies of high circuit impedaiice low current electrodes or discharge device 87, which may be insulated from the support 54 by insulating spacers 88 in any well-known fashion. The purpose of the. coil 85 and the discharge devices 87 is to establish an initial breakdown or plasn'ja discharge such as at 28}, which will ionize the atmosphere and thereby provide for a breakdown at a lower"voltage, and which also insures more rapid high-current conduction through the plasma. The embodiment of 11 and 12 is not only useful for initiating current conduction in a D.C. embodiment, but for achieving a full duty cycle in an alternating; current embodiment. If an} alternating current poweif source 32 (FIG. 1) is utilii ed, then the high-voltage coil 85 should be energized with substantially a 90 ,phase lead or lag from the rnain power source, whereby maximum breakdown to the auxiliary electrodes 87 is provided at the start of each half cycle, with the same polarity as the current forthe ensuing half cycle. A plurality of secondary electrodes 87 are provided transversely of the catenary 26 so that if the vehicle establishes a transverse position other than completely centered beneath the catenary 26, one of the secondary electrodes 87 will be sufficientlymlose to the ultimate path of the plasma between the catenary 26 and the conductii g web 36 so as to initiate a discharge therebetween.

According ito a further aspect of the present invention, the work function of discharges for high current conducting plasma between a catenary and a moving vehicle may be lowered through the utilization of radioisotopes. Radiosotopes may be embedded in a regular conducting metal as illustrated in FIG. 13. On theother hand, radioisotope. material may be plated or painted onto conductingmefal as illustrated in FIG. 14. The radioisotope utilized must be chosen with public safety in mind, so that resulting radiation will not be harmful. Thus, if strontium 90 is chosen, very good electrical discharge will result between the catenary 26 and any of the electrode embodiments disclosed herein; however, unless suitable shielding is provided, damage to living tissue in the immediate area may result. On the other hand, an isotope such as cerium may be utilized which provides basically short range alpha particles requiring less shielding and isolation. The safer isotopes will, however, result in a lesser effect upon the discharge, and therefore the choice of the isotope together with the amount of shielding (not shown) is left to the skill of the art to suit the design parameters of any given utilization of the present invention.

The teachings herein are also applicable to third-rail type electric vehicles.

Although the invention has been shown and described with respect to preferred embodiments thereof, it should be understood by those skilled in the art that the foregoing and other changes and omissions in the form and detail thereof may be made therein without departing from the spirit and scope of the invention.

Having thus described typical embodiments of the invention, that which we claim as new and desire to secure by Letters Patent of the United States is:

1. In a. vehicle having a. pantograph or the like mount ing an electrode adapted for conduction of electrical currents to or from a catenary wire, the combination comprising:

an electrode includin a conducting surface having a dimension extending transversely with respect to the catenary wire;

positioning means-including means for sensing the relative positions of said surface and the catenary wire and means responsive thereto, for positioning said surface in proximity with the wire but separated therefrom by alfgap suitable for plasma conduction therebetween;

and means for providing motion of said surface transversely of the wire. 2. The electrode according .to claim 1 wherein said surface comprises a moving belt.

3. The electrode according to claim 1 wherein said surface comprises: f

an electrically conductive disc disposed for rotation about an axis perpendicular g to said catenary wire;

and a disc of dielectric material having a diameter less than the diameter of said conductive disc interposed between the catenary wire and said conductive disc, whereby plasma. is forced tciward the periphery of said electrically conductive disc.

4. The electrode according to claim 1 including surface discontinuities on said conducting surface disposed so that said discontinuities provide 2.? sequence of raised surface portions to said catenary which traverses said cate- 30 nary wire as a result of motion-of said conducting surface, whereby the point of impingement of plasma on said catenary wire varies with the position of said raised surface.

5. The electrode according to claim 1 further including a field producing coil and a secondary electrode, said secondary electrode located between said conducting surface and said catenary, said coil, supplying a field pro ducing potential to said secondary electrode relative to said catenary wire, whereby electrical breakdown be tween said catenary ,wire and said conducting surface is initiated by a breakdown from ;said secondary electrode.

6. The electrode'according to claim 1 wherein said surface has a radioisotope material embedded therein.

7. An electrode adapted for mounting on a pantograph or the like ofjia moving'vehicle for the conduction of electrical currents' transmitted thereto across an intentionally maintained igap through the medium of plasma impinging thereon m a catenary wire; comprising:

an electrical condiigiting surfacb having a configuration extending transyersely of said catenary wire;

an electroma'gnet disposed beneath said conducting surface with the poles thereof located on transversely opposite sides of said catenary, whereby the magnetic field from said electromagnet forces the current conducting plasrria between said catenary wire and said conductive surface to various points along said catenary and said surface as a result of the direction and intensity of magnetic flux applied by said electromagnet.

8. The electrode according to claim 7 wherein said surface has a radioisotope material embedded therein.

ARTHUR L. LA POINT, Primary Examiner G. LIBMAN, Assistant Examiner US. Cl. X.R.