US1506748A - Electromagnetic fuse - Google Patents

Description

Sept. 2, 1924. 1,506,748

J. w. HAYwooD ELECTROMGNETIC FUSE mwl 2 4o zo IN V EN TOR,

J ATTORNEY )1 Sept. 2 1924.

J, w. HAYWOOD ELECTROMAGNETIC FUSE Filed July 1. 1920 2 Shouts-Sheet P INVENTOR ATTQRAIEY4 @o 7. av 2 1.. 2 2 llllllln 5l 1.

Patented Sept. 2, i924.

UNITED STATES htli PATENT OFFICE.

JOHN V. I'TAYWOOD, 0F NEW YORK, N. Y., ASSGNOR, BY MESNE ASSGNMENTS, ISO

HORNE ELECTRIC 8c MANUFACTURNG COMPANY,

JERSEY.

Application filed July l,

To @ZZ 107mm t may concern.'

Be it known that I, JOHN W. HAYwooD, a citizen of the United States, and resident of the borough and county of Bronx, in the city and State of N ew York, have invented a new and useful Electromagnetic Fuse, of which the following is a specification.

The object of the invention is to provide a serviceable device performing the functions of a fuse and interchangeable therewith in the regular fuse-clips and fuseboxes, but which is not destroyed in operation and is instantly restorable to normal condition. The device comprises an electromagnetic circuit-breaker with magnetic blowout, constituted within the approximate lateral and longitudinal limits of a fuse of like capacity, upon a narrow base having terminals adapted to lit between the fuse-clipsln the accompanying drawings forming a part hereof:

F 1 is a side elevation of the device in the open condition;

2 is a vertical longitudinal section showing the closed condition;

Fig. 3 is a sectional plan on the line 3-3 of Fig. 2; f

Fig. l is a. vertical transverse section on the line M4 of Fig. 1;

Fig. 5 is a rear end elevation;

Fig. G is a fragmentary section in the vertical longitudinal plane, illustrating a modification in the closed condition; and

Fig. 7 is a similar view with parts mainly in elevation, showing the open condition.

The device has a narrow base 1 of insulation, approximating in length and width the dimensions of a. fuse body. The base is hollow and open at the top, and a deep chamber is completed by a hollow cover 2, which is preferably closed at the rear end and open at the front. Conducting menr bers 3, 3a are embedded in or otherwise se cured to the ends of the base and are constructed to afford terminals t, 4a adapted to be slipped into ordinary fuse-clips. ln the illust-rated construction the terminals are of the well-known blade form.

An arm 5 is disposed in generally longitudinal relation over the base, this arm being electrically connected with the rear fuseclip terminal e' and cooperating with a stationary contact 6 connected with the front terminal ll and mounted to swing in the A CORPORATION OF NFFN ELECTROMAGNETIC FUSE.

1920. Serial No. 393,387.

vertical longitudinal plane of the base. The body of the arm is preferably rigid and pivoted toward its rear end upon a transverse pin 60, the rear portion 7 of the arm being bifurcated to embrace the standard et' a bracket 8, by which said pin is carried. A spring 9 connected to a tail extension 10 of the arm and anchored to a fixed frame 11 constantly urges the arm to assume the open position of Fig. 1.

The frame 11 is of magnet-ic material and forms part of the electromagnet 12, by which the arm is caused automatically to open when the current in the protected circuit exceeds a predetermined value, such movements being produced by the spring 9 upon the displacement of a latch 13, 'by which the breaker arm is normally restrained. As illustrated, the frame 11 coniprises a vertical bar, embedded or otherwisev secured at the rear end of the magnet chamber lil of the base and rising therefrom within the enclosure of the cover, together with two horizontal longitudinal cores 15, which are united at their rear ends to the bar and extend forwardly one above 'the other. The bar 11 of the magnet frame is bent forward at the top to provide a longN tudinal top extension 16, by which the pi\'- oted bracket S is supported, being secured thereto by screws 17, 18. A forward support for the cores l5 and the top extension 15 is constituted by a vertical bar 19 of nonmagnetic material, the lower end 2O of which is angled and planted in the base while its upper end 21 is reversely angled and united to the top extension by the screw 18. Two holes in the forward support 19, one above the other, receive reduced end extensions 22 on the cores. The energizing coils 23 are formed and slipped on to the cores prior to the application of the piece 19. Said coils are included in the circuit between the terminals et, 4t, being preferably connected on the one handwith the terminal piece 3, as indicated at 2a', and on the other hand with the pivot bracket 8, by means of a. clip secured by the screw 17 and holding the end of the wire of the upper coil.

he pivot bracket 8 is made of conducting non-magnetic material like that of the arm 5 and the pivot pin 60.

The polar extremities of the cores 15 are in attracting relation to the vlatch 13, which is of magnetic material and constitutes a` the member 19.

pivoted armature for the magnet. The latch, thus positioned, cooperates with a portion of the breaker arm 5 intermedia-te its hinge or mounting and its forward or contact portion. In the illustrated construction it consists of a bar united at its lower end to a transverse pivot pin 26 in the forward part of the chamber 14 of the base and extending therefrom substantially vertically through the bifurcated portion 7 of the breaker arm and a slot 27 in the top of the cover. At its upper projecting end it is provided with an insulated resetting handle 28. The pivot 26 is journaled in the arms of a yoke bracket 29 fixed to the base by a screw 30 securing it to the foot 2O of An opening 31 is formed in the upper part of the latch, with its upper edge 32 "beveled toward the front, to presenta holding edge or catch portion for cooperation with a screw 33 which passes rearwardly through a screw-threaded opening in an offset 34 of the arm 5. The rear extremity 35 of said screw is reduced. and unthreaded, so as to form a lateral cylindrical catch surface and a rearwardly facing 'alibrating shoulder 36. In the closed condition the side of said reduced portionr bears against the holding edge of the latch 13, so that the breaker arm is positively held against the pull of the spring 9. rl`he shoulder 36 bears against the front face of the latch, and consequently by turning` the screw in one direction or the other the air gap between the armature and magnet can be varied. The latch is urged in the holding direction away from the magnet by a spring 37, one end of which is held in a transverse hole in the pivot 26 while the opposite end is bent to bear upon the upper end of a screw 38, constituting another calibrating means occupying a screw-threaded opening in the bottom of the base.

The stationary main contact 6 at the forward end of the base is advantageously formed as a shelf integral with the terminal piece 3 and projecting at an inclination inward and upward therefrom within the cover 2 and over a forward blow-out chant ber 39 in the base, the said chamber being separated from the magnet chamber' by a vertical transverse wall of insulation 40 rising behind the contact 6 to within a short distance of the normal or closed position of the breaker arm.

The breaker arm 5, from its elevated pivot. inclines forward and downward in the closed position to bear at its contact portion upon the stationary contact 6, and when the latch is retracted flies up to or slightly beyond the horizontal, as limited by the top of the cover 2. The space below the rear part of the arm is utilized for the laterally-compact upwardlyprojecting electromagnet 12, A blow-out coil 41, consisting of numerous turns of tine wire, is housed within the chamber 39, beneath the contact 6. The core 42 of this coil is disposed transversely, being supported in openings in the side walls of the base, outside of which said ends are neath the cover of an ordinary fuse-box.

In the preferred construction of the con tact portion of the device, the movable main break contact is formed by the forward part of the arm 5, the under side of which bears tlat upon the upper face of the inclined stationary contact 6 when the arm is closed. A. goed contact is insured by providing one of the members-in this instance the armwith a soft conducting facing 44 of woven wire or the like, which is brought up over the sides of the arm and secured at the ltop beneath la block 45 fastened to the arm by screws 46, 47. Carbon secondary break contacts 48, 4S) are also provided, and in the illustrated construction are disposed in advance of the main break contacts. rlhe lower contact 48 is carried by a depressed portion 5t) of thev shelf 6, which forms the lower main break contact, and is insulated from this contact and electrically connected with one end of the blow-out coil 41. For this purpose the supporting part 50 is formed with an opening through it, in which is held an insulating bushing 51, whereon the contact 48 rests. An axial conducting screw 52 secures the contact 48 to the bushing, and is connected at its lower end to the terminal 53 of the blow-out coil, the other terminal 54 of said coil being electrically connected to the terminal piece PN. The upper carbon contact 49 is fastened by a screw 55 to the end of a leaf spring 5G, which projects forward from the breaker arm, to which it is secured by the screw 47. A The relations are such that when the breaker arm is closed the spring 56 is flexed away from the top of the breaker arm and under tension, so that, when the arm starts to open, the carbon contacts 48, 49 remain in contact for a brief period after the main contacts have separated. The blow-out coil, it will be observed, is in shunt to the primary break and in series with the secondary break, so that it is short-circuited, or shunted out of circuit, when the arm is closed and momentarily carries the full current when the arm starts to open. By energizing the magnetic blow-out for only a brief period it is possible to use a very small coil composed of line wire, obtaining an efficient blow-out occupying little space in the electromagnetic fuse. Such a coil can be conveniently disposed in the preferred and advantageous manner illustrated,

whereas a coil in circuit all the time would have to be of coarse wire and of relatively large size. Other forms and arrangements involving a normally cle-energized blow-out may be substituted.

The operation will be readily understood. Current may be regarded as passing from the rear terminal a to the coils 23 of the electromagnet, thence to the mounting 8, to and through the breaker arm, to the stationary contact 6, and thence to the terminal da. Unless the current increases to the value at which the device is designed to act, the pull of the magnet is insuiiicient to retract the latch 18 and the breaker-arm is held closed. If such value is exceeded, however, the latch is displaced, and the arm flies open under the action of its spring, the magnetic blowout then acting to suppress the arc which would otherwise occur.

Figs. 6 and 7 illustrate an alternate form. The device as a whole may be and preferably is constructed and arranged as in the other views, but the primary and secondary break contacts are differently disposed. The forward contact portion of the breaker-arm a does not bear directly upon the main stationary contact 6a, but upon an interposed movable contact member 65, which normally rests upon the top of the contact 6a. The interposed contact 65 is the equivalent of two contacts in one, a primary break occurring between it and the Contact 6' and thereafter a secondary break between it and the breaker-arm when the latter is opened. In the particular form illustrated the member comprises a plate, from the bottom of which there projects a stem 66 passing through an opening in the contact 6a. Said stem is insulated from the contact 6a by a bushing 67, wherein the stem is guided, and a spring 68 in the chamber of said bushing constantly urges the member to leave the contact 6a. A stop 69 on the lower part of the stem limits the member 65 to a restricted movement. The magnetic blow-out coil ll is connected at one end with the stem 66 of the member 65 and at the other end with the terminal member of the fuse, or, which amounts to `the same thing, with the stationary contact 6a. In this case the current normally passes from the breaker-arm 5L through the intermediate member 65 to the stationary contact 6a, and the blow-out coil is shunted out of circuit as in the other form. When the arm starts to swing away from the base in the opening movement, the member 65 urged by the spring 66 leaves the contact 6a, thereby opening the circuit at this point, and follows in contact with the breaker-arm for a short distance. During this briefI period the current is caused to flow through the blow-out coil, and the blowout magnet is thereby energized. The member 65 soon reaches the limit of its movement, while the breaker-arm continues to fly upward, and a secondary gap of comparatively wide extent is opened between it and the member 65, the arc which would occur at this region being suppressed by the blowout.

lVhile the preferred embodiment has been described in detail, it will be understood that numerous changes may be made in respect to form, proportions, arrangements and reversals without departing from the invention. Terms of orientation are, of course, relative, as the device may be installed in any position.

Wlhat I claim as new is:

l. In an electromagnetic fuse, a contact plate, an extension therefrom, an arm adapted to Contact with said extension and forming the main circuit, a magnetic coil arranged adjacent said plate and having one vof its ends electrically connected therewith, an insulating bushing extending through said extension and a pin extending through said bushing and in electrical contact with the other end of said coil to form a secondary or blow-out circuit, adjacent to said main circuit.

2. In an electromagnetic fuse, a contact plate, an extension therefrom, an arm adapted to contact with said extension and forining the main circuit, a magnetic coil arranged adjacent said plate and having one of its ends electrically connected therewith, an insulating` bushing extending through said extension and a block upon said bushing, a plate under said bushing, to which said coil is connected, means extending through said bushing for connecting said block and said plate and a block flexibly supported upon said arm, adapted to contact with said first mentioned block.

3. An electromagnetic fuse, comprising a narrow movable base having terminals on the ends thereof adapted to lit between fuse-1 clips, a generally longitudinally breakerarm on said base, an armature latch pivoted on the base and extending upward therefrom to cooperate with an intermediate portion of the breaker-arm, an electromagnet comprising a limb secured to the base and having a forwardly overhanging extension, and a plurality of coil-bearing cores secured to said rear limb extending parallel there-- from 'one above the other into operative relation with the latch, a pivot mounting for the breaker-arm on said top extension, and a forward support for the cores and top extension.

a. An electromagnetic fuse, comprising a narrow movable base having terminals on tlie ends l'llereo'f adapted to lt between fase-clips, a generally longitudinal breaker- N arm on said base, electromagnetic means controlling the release of said arm a sta- 5 tionary Contact connected with one of the fuse-clip terminals and disposed over the forward part of the base to cooperate with the forward part o the breaker-arm, and a magnetic blow-out having a core and coil in a chamber beneath said contact and in rear of said terminal and magnetic side pieces arranged adjacent the ends of the core of said blow-ont coil and embracing the region of the break of tlie main contact.

JOHN W.- HAYVOOD.

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