Patent GB-190406042-A (GB)
Title: Improvements in Electric Arc Lamps
Inventor: LEVIS HOWARD COPPUCK
Filed: 1904-03-11
Granted: 1905-02-16
Abstract: 6042. Levis, H. C., [General Electric Co.]. March 11. Arc lamps.-Relates to lamps having a non-consuming positive electrode and a negative electrode of a material, such as magnetite or titanium carbide, which gives a flaming arc. The electrodes are brought together, when the current is switched on, by means of an intermittently-excited electromagnet, the armature of which actuates a ratchet-wheel by means of a pawl. When current flows through the electrodes, this electromagnet is cut out of circuit, and the ratchet-wheel freed, so that the lower electrode descends a predetermined distance and strikes the arc. The frame comprises a hood 1 carrying binding-screws 3, 3' and supporting means for the lamp, a tubular piece 4 fastened by screws to the hood, a plate 5, rods 6, a plate 7, and screws 9 supporting an annular disc 8, to which is attached a cylinder 8<1>. The electrode 13 of copper or other good conducting material is attached to a plate 10 of similar material, which is supported by the screws 9 and insulated therefrom by means of tubular spacing-members 11. Surrounding the electrode 13 is an insulating-layer 14 of mica or the like, and outside this a sleeve 15 of porcelain. The cylinder 8<1>, sleeve 15, and electrode 13 are of equal length, but the layer 14 is somewhat shorter, in order to leave a space round the end of the electrode. The holder 17 of the lower electrode 16 is attached to a crosshead 18 carried by rods 19, which are united at their upper ends by a crosshead 18', and slide in insulating-busbes 20 through the plates 8, 10, 7. To the crosshead 18<1> is fixed a rack bar 21. A shaft 22, mounted in bearings 23 on the bars 6, carries a pinion 24, gearing with the rack 21, and a ratchet-wheel 25. The electromagnet 26 is supported by a piece 27 of magnetic material attached to the plate 7, preferably by means of screws 29 which take into the cores 28 of the magnet. The armature 30 of the magnet 26 is pivoted to a yoke 32 attached to the plate 7, and a spring 33 tends to withdraw it from the magnet against a stop 34, which may be formed by a reduced extension of one of the cores 28, bent at its end. Pivoted to the armature 30 is a spring pawl 35, and also an arm 36, having an offset portion 37 at its end, and adapted, when depressed, to move the pawl 35 out of its normal engagement with the ratchet-wheel 25. A second spring pawl 38 normally prevents rotation of the ratchet-wheel in the direction contrary to the arrow in Fig. 2. When the electromagnet 26 attracts its armature 30, a rod 42 carried by the latter moves an insulated spring arm 39 away from a contact piece 40 carried by another insulated arm 41, thereby breaking the circuit through the magnet 26. A shunt circuit containing a resistance coil 74 supported by brackets 73 from the hood 1 is provided. The oscillatory motion of the armature 30 causes the ratchet-wheel 25 to be rotated and the lower electrode raised. Connected in series with the electrodes is an electromagnet 43, the armature 44 of which is pivoted to a post 45 and connected by a spring 46 to an adjustable bolt 47. When the electromagnet 43 is excited, the end of the armature 44 depresses a spring arm 52 away from a contact-piece 53 carried by an arm 49, thus breaking the shunt circuits through the resistance 74 and electromagnet 26. At the same time, collars 55, 55<1> on a rod 54, hinged to the armature and guided by the plate 5, through a hole in which it passes, strike the pawl 38 and the end 37 of the arm 36, thereby freeing the ratchet-wheel from both pawls and allowing the rack bar 21 and lower electrode 16 to fall by their own weight. The arms 52, 49 are fixed to a block 50, carried by a bar 51 clamped to two of the rods 6, and the arm 49 is provided with a stop 48, which limits the upward movement of the armature 44. A post 56 stands up from the plate 7, and is embraced by a clutch, consisting of a sliding sleeve (not shown), to which is pivoted a lever, having its shorter arm bevelled and formed with a sharp edge. The weight of the longer arm of the lever causes this edge to grip the post 56. The longer arm has an aperlure through which passes a rod, attached to the cross-piece 18<1>, and provided with two collars, one on each side of the lever. When the electrode 16 is raised, the lower collar lifts the lever and sleeve, but the electrode can only fall until the upper collar meets the lever and presses it into engagement with the post 56 at its bevelled end. The clutch can be lowered when required by a block which can be slid down over the post 56 by means of a rod and operating-button, and is normally retained in the position shown by a spring clip. If it is desired that the electrode 16 should be fed without the arc being broken, a device such as a shunt electromagnet may be provided, which shortcircuits the electromagnet 43 when the potential difference between the electrodes becomes too high. The current is conveyed to the positive electrode by means of a bushing (not shown) which makes sliding contact with the rack bar 21. The casing consists of a cylinder 66 attached to the plates 5, 7, and a concentric cylinder 67, provided with a flange secured to the plate 8. Lugs 70 on the plate 8 are provided with screws 70<1> by which the globe 71 is secured, apertures 72 being left for ventilation. The cylinders 66, 67 are secured together by means of tubular pieces 69. The hood 1 is extended outwards to prevent the access of dust into the space between the cylinders.