US2208407A - Fuse - Google Patents

Description

July 16, 1940. T. BIRKENMAIER FUSE Filed March 24, 1939 2 Sheets-Sheet l FIG. l.

July 15, 1940- T. BIRKENMAIER 2,208,407

FUSE

Filed March 24, 1939 2 Sheets-Sheet 2 19% Flc/5,6 Flos.

Patented July 16, 1940 PATENT OFFICE FUSE Theodore Birkenmaier, St. Louis, Mo., assigner to l W. N. Matthews Corporation, St. Louis, Mo., a

' corporation of Missouri Application March 24, 1939, Serial No. 263,857

4 Claims.

This invention relates to fuses, and with regard to certain more specific features, to closed type fuse switches.

This invention is an improvement upon the construction shown in my VUnited States Patent 2,176,045, dated October 17, 1939 for Fuse.

Among the several objects of the invention may be noted the provision of a closed type of fuse switch of the class shown in said application 10 in which a greater visible indication and electrical clearance is provided in its blown condition; and the provision of a switch of the class described in which a more complete enclosure is provided under unblown conditions. Other ob out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which is illustrated one of various possible embodiments of the invention,

Fig. 1 is a vertical section through the apparatus which is shown in closed, circuit-oonnectingposition;

Fig. 2 is a 'horizontal section taken on line 2--2 of Fig. 1;

Fig, 3 is a horizontal section takenl on line 3-3 of Fig.\1;'

Fig, 4 is a bottom plan view of Fig. 1;

Fig. 5 is a view similar to Fig. 1 showing an intermediate blown condition, certain parts being shown in elevation;

Fig. 6 is a view similar to Fig. 1 showing a final blown condition, more parts being shown in ele- 40 vation;

' Fig. 7 is a view similar to Fig. 6 but in which the fuse switch is shown partly open and about to be closed;

Fig. 8v is van oblique section taken on line 8 8 45 of Fig. 7; and,

Fig. 9 is a fragmentary vertical section taken on line 9 9 of Fig. 6. I

Similar reference characters indicate corresponding parts throughout the several views A50 of the drawings.

Referring now Imore particularly to Fig. 1, there is shown at numeral I a box made of insulating material such as porcelain, supported by means of bolts 3, and having therein conduct- 55 ing line terminals 5. The line terminals in- Cfr jects will be in part obvious and in part pointed will be exemplified in the structures hereinafterv (Cl. 20G-114) clude wire clamps 1 for respective line wires (not shown).

Associated with the upper line terminals 5 is a riveted U-shaped spring conducting member forming a knife type of contact 9. This contact 5 is of the variety in which the opposite holding faces of Athe spring members are substantially parallel. To the lower line terminal 5 is riveted a different type of spring conducting member II) (Fig. 10 9). This conducting member I0 is characterized by the fact that the spring arms are flared in a downward direction, and also outward. 'Ihe arms are of springlness similar to that of the spring arms forming the knife contacts 9. The box l has a large opening at the bottom, as indicated at II. The unrestricted character of the opening simplifies the manufacture of the box, besides having other advantages which will be particularized. The box also has a front opening I3 covered by a door I5 hinged on a pin I1. The door I5 is made of insulating material, such as Bakelite, for example. Unlike the door of said. application, the present door I5 is hinged at its upper end, the pin I1 being at the 25 upper portion of the box I. 'I'he hooked-shaped portion I9 on the door which makes a hinge element is open as shown at 2| so that the door may be removed from the box after it has been pulled to an open position. A ring 23 is provided for 30 manipulation.

The' door I5 has attached thereto, by means of screws 25, an upper, hollow, terminal-engaging element 21, made of conducting material, having flat sides 3l for engagement with the fiat 35 sides of the U-shaped spring conducting contact 9 of upper line terminal 5.

The spring pressure between the spring arms of contact 9 and the terminal-engaging element 21 is substantial, so that a good contactis obtained under operating conditions without undue temperature rise in the switch. Y The lower outer corners of the spring arms of contacts 9 are flared as shown at 30 to function as guides for the diagonal entrance of the upper 45 terminal-engaging element 21. It will be noted in this connection that element 21 swings around y the center of the pin I1 and therefore enters the. contact 9 diagonally from below. It is for this reason that the flare is angled. 50 'I'he hollow portion of the upper terminal-engaging element 21 is open at the top and bottom, and at the top is threaded to receive an enclosing cap 35. The cap also functions as a clamp for the upper headed end 31 of a fuse link 39. 55

The fuse link 39 has a fusible portion 4I adapted to melt upon overload and to open the circuit. Its lower end is composed of flexible conducting wire 43. 'A

The fuse link39 passes through a fixed, inner, insulating tube 45 which is rigidly supported at its upper end by threading to the upper terminal- `engaging element 21. 'Ihe lower end of the tube 45 is open, as indicated at 41.

.Slidably arranged on the insulating tube 45 is a second insulating tube lor sleeve 5I. The lower end of the sleeve 5I is provided with a relatively xed collar 51 which may or may notbe made of conducting material,.althou gh in the present embodiment it is so shown. This collar is formed on one side with a smooth, rounded, anti-friction saddle 59 which permits sliding thereov'er of the fuse link wire 43 and directs it into tube 4s.

The top of the collar 51 forms a seat for a flat bottom 2 which encloses the opening II (when the door I5 is closed). The bottom 2 is Y flexible part 43 of the fuse link.

The bottom 2 also forms a seat for a spring 6I. Above the spring 6I and slidably arranged upon the outside of the sleeve 5I -is a lower terminal-engaging element 63,"composed of conducting material. This element or contact 63 is attached by means of screws 6 to an insulating guide plate B. The screws Ii also extend into and slide in a slot 53 arranged in the tube 5I,

Vvsuch that there is a limited relative motion bewhich surrounds a stationary pin I4 on the door I5 (Fig. 8). By this means the relative motion ofthe plate 8 (and consequently also ofthe v,lower terminal-engaging element B3) and the door I5'is allowed to the substantial extent indicated by comparing Figs. 1`and v6.4 Since the 'Y plate 8 is atwise against the door I5,-it prevents rotary movement of the tube 5I on the tube 45. v

The lower Aterminal-engagingelement 63 is of special form tomate with the lower line terminal III, that is, the contact 63 flares downwardly primarily (Fig. 8). It also ares somewhat'in the direction of the door.

Aociated with the terminallengaging ele- Ament 63 is a clamp 68 threaded ,on a stud 66, by, means of which the lower end 43 ofthe fuse link 39 may be bound vto the-terminal-enjgaging element 63.

y Operation of the device is as follows, assuming anew fuse is required:

cap 35 is removed and the old upper fuse portion element removed. Such lower fuse element V43 as may beheld by the clamp nut 68 The newfusefis fed (flexible part 43 first) of the movable ring 51. It is threaded around the smooth saddle 59 and then turned upwardly through the slot 4. Its end is 4then fastened by means of the clamp 68. Before fastening is made, as much as possible of the fuse end 43 is drawn from the tube 45, thus tensioning the fuse 39. Tension may or may not be placed in the spring 6I at this time. In any event the slidable tube 5I (fastened to the collar 51) is pushed up as high as it will go on the fixed tube 45.

Next, the door I5, while open, has its hook I9 applied under the pin I1 (Fig. 7) and is then 'rotated down into closed position (Fig. 1). This causes the `upper fiat-faced terminal-engaging element 21 to be frictionally engaged by the flatfaced spring arms 9.

The lower terminal-engaging element 63 is at this time at such an elevation on door I5 that it is springingly engaged by the spring arms I0 of the lower line terminal. The reaction between the outwardly and downwardly flowing line arms I0 and the upwardly and inwardly tapered terminal-engaging element 63 causes the latter to be pressed downwardly against the spring 6I to. compressthe latter. This pushes down saddle 59v and places tension in the fuse link. It should be understood at this point that the bottom 2 moves with the collar 51 and is free of the plate 8, although slidable thereon. The elementv 63 and the plate 9 move down twice the distance that the fuse link 39, 43 allows collar 51 and tube 5I to move down.

At this time, the reaction between the terminal-engaging element 63 and the clip I0' causes a. satisfactory low-resistance surface contact which has the effect of preventing the building up of switch temperatures.

The surfaces between the terminal-engaging element 63 and clip I0 are so arranged that the component of force exerted downwardly is of a degree properly to tension the fuse link. 'I'he direction of this force for contact reaction is such that the door I5 is not forced 'open against the holding 'action of clip 9.

Upon overload, the vfusible fuse portion 4I melts or blows. This releases the saddle 59. and the spring 6I, having theretofore been under compression, forces the saddle down. This must be, because the terminal-engaging element 63 is held down by clip I0. The saddle 59 being part of the collar 51 draws down the attached outer tube 5I,-until the upper end of theslot 53 (in tube 5I) strikes the end of the upper one of the\screws 6 (Fig. 5). v

Ihis provides an impact or blow to the lower terminal-engaging element 63 to drive it away from engagement with the line terminal I0. It is to be understood, however, that even without this blow the spring squeezing action of the lower downwardly flared line terminal I0 would normally squeeze the terminal-engaging element 63 out and downso that the latter would be forced out of contact. It will be understood that at this time there may also be an expulsive action -through the tube 45 due to blowing of the fuse link, depending upon the degree of overload.

As indicated inl Fig. 6, theassembiy of tube` 5I., element E3, Vcollar 59, bottom 2, spring 6I and plate '8-slidcs downuntil the pin I4 on the door I5 is reached by the end of the slot I2. Support is then by the pin I4, the short telescoped relationship between tubes 45 and 5I at T functioning to steady the assembly. At this time, Vthe lower portion ofthe fuse link 43. hangs downwardly. It 'is at this time'electrically dead,

since the terminal-engaging element 63 is separated from its line terminal l0.

Among the advantages of the invention are those specified in my said prior application, together with the following:

By eliminating the hinge at the bottom of the door and placing it at the top of the door, the bottom of the box is left entirely ,clear for clearing parts to drop. Thus it is practicable to employ an enclosing bottom which may drop away as described, without increasing the size of box I. Another feature is that more visibility is 0btained by dropping down more parts for a greater distance. More parts can be dropped away because there is no interference at the bottom opening of the box when the hinge is arranged at the top.

Also, better visibility is obtained to indicate blown conditions, and better electrical clearance is obtained. At the same time, the circuit opening parts are held captive.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown iii) in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

1. A fuse switch comprising a box, line terminals in the box, said box having an open front and an open bottom, a'door hinged near the upper end of said opening, a fuse supported on the door, terminal-engaging elements on 'the fuse engageable with the line terminals when the door is closed, one of said terminal-engaging elements being releasab'le from one of the line terminals when the fuse blows, means movably supporting said releasable disengaging element directed to direct the element out of said bottom opening of the box when' the fuse blws, andl means associated with the disengageable elementl to close the bottom of the box during engagement but to open said bottom upon disengagement.

2. A fuse switch comprising a box having a side opening and a bottom opening,.upper and lower line terminals in the box, a door for the box hinged near the top of said side opening,

a fuse carried by the door having an upper xed terminal-engaging element for iixed engagement with the upper line terminal, a lower terminalengaging element movable on the door, a. fuse link rjoining said engaging elements and adapted when unseparated to hold the lower engaging element in position for engagement with the lower line terminal upon closure of the door, said movable engaging element upon blowing of the fuse being adapted to move away from the lower line terminal and out oi the bottom of the box.

3. A fuse switch comprising a box having a side opening and a bottom opening, upper and lower line terminals in the box, a door vfor the box hinged near the top of saidy side opening, a fuse carried by the door having an upper ilxed terminal-engaging element for fixed engagement with the upper line terminal, a lower terminalengaging element movable on the door, a fuse link joining said engaging elements and adapted when unseparated to hold the lower engaging element in position for engagement with the lower line terminal upon closure of the door, said movable engaging element upon blowing of the fuse being adapted to move away from the lower line terminal and out of the bottom of the box, and a bottom carried with said movable engaging element adapted to close the bottom opening when the movable engaging element is engaged and vice versa.

4. A fuse switch comprising a box having a side vopening and a bottom opening, line terminals in the box, a door for the box hinged near the top of said side opening, a fuse carried by the door having an upper xed terminal-engaging element for engagement with the upper line terminal in the box, a lower terminal-engaging element movable with respect to the door, a fuse link joining said engaging elements and adapted when unblown to hold the lower engaging element for engagement upon closure of the door, said movable engaging element upon separation of the fuse link beingl adapted to move away from the lower line terminal and out of the opening at the bottom of the box, a bottom for the box carried by said movable engaging element and adapte ed to be positioned to close said bottom opening 'when the movable engaging element is engaged and to move away from said opening upon disengagement of the movable engaging element.

l THEODORE BIRKENMAIER.

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