US2115436A - Electric arc breaker - Google Patents

Description

. April 26, 1938. K. U'rsUNoMlYA ELECTRIC ARC BREAKER Filed Aug. 19, 1935 EES INVENTOR. Enzo UrsuNoM/yn 71j.. ATTOR EYS.

Patented Apr. 26, 193s` UNITED STATES PATENT OFFICE ELECTRIC ARC BREAKER Kenzo Utsunomiya, Shiba-ku, Tokyo, Japan Application August 19, 1935, Serial No. 36,785

1 Claim. (Cl. 200-131) The present invention relates to an electric fuse device, which consists in providing an elastic thin walled cylinder encircling a fusible member and v mounted in an outer insulating cylinder, whereby 5 the breaking of the arc formed by the fusing of the fusible member is accelerated by utilizing the interna] pressure produced upon the formation of an arc to .discharge the fusible member from the outer cylinder. The fusible member is suitably enclosed to prevent dust and moisture from entering the interior of the device so as to make it suitable for use for a high voltage circuit and increase the life of the device. The object of the invention is to control the scattering of the electric are and burnt metal powder produced when the fusible member is fused, and also to prevent the burning and destruction of the outer insulating cylinder.

The appended drawing shows as an example three embodiments of the electric fuse device according to this invention, wherein Figure 1 is a longitudinal elevation of the rst embodiment of the electric fuse device according to this invention;

Figure 2 is a view looking at the bottom of Fig. 1:

Figure 3 is a side view of the second embodiment, partly broken away; and

Figure 4, a side view of a high voltage electric fuse device which is the third embodiment, partly broken away.

'I'he embodiment of the invention illustrated in Figs. 1 and 2 of the accompanying drawing, comprises an outer insulating cylinder Imade of glass or other transparent insulating material having electric conducting terminal pieces 2 and 3 of tubular form fixed to both ends of the outer insulating cylinder by a binding material 4 or other suitable means. A fusible member Sis mounted sub- 40 stantially centrally in the outer insulating cylinder I by a plate 6 of electric conducting material connected to an end portion of the fusible member and engaged in the terminal piece 2 to fix said end portion of the fusible member in position on the interior of the terminal piece 2 with a nut 1 screw threaded in the piece 2 to retain the plate in position. The terminal piece 2 is closed tigl' .ly by the plate 6, nut 1 and a cap 8 which is provided vwhen necessary. A cap 9 is inserted in the open end of the terminal piece 3 and secured therein Around the fusible member 5 there is arranged one or more inner insulating cylinders H, II which are made by rolling or pasting together a resilient or elastic insulating material such as cellophane, uninflammablc Celluloid, or the 5 like, into cylindrical shape. To the plate 6 and cap 9 there are attached short metallic tubes I2 respectively, and in the interior or exterior of which there is engaged the inner insulating cylinder II to support the said cylinder' II' and 10 also receive pressure as described hereinafter.

, The inner insulating cylinder II is wound spirally with an electric conducting sheetI I3 such as a tin foil, or the like, and is connected to an electric conducting ring I4 by a conducting wire, so 15 that it may not only be expelled with'the cap 9 from the cylinder I, but also thc tin foil I3 may be of the same potential as the terminal piece 3, thus preventing the formation of corona. The elastic legs I0 are fixed to the cap 9 as'shown in Fig. 20 2 and to maintain the legs in engagement with the periphery of the terminal piece 3 there is provided a clamping ring I5, for example, a locking wire or tightening plate. Further, by inserting the periphery of the cap 9 in the peripheral 2.- groove I1 of the terminal piece 3 and packing this part with a sealing agent such as litharge or gum packing the electric fuse device may be given a watertight construction suitable for th outdoor use. 30

The following is an explanation of the operation of the electric fuse device of the present invention.

When the fusible member 5 starts fusing at a starting point which is a reduced portion I6, inf- 35 ternal pressure is produced in the inner insulating cylinder I I by the fusing of said fusible member. 'I'his pressure is received by the short metallic tube I2 due to the elasticity of the cylinder II'. above internal pressure directly to the cap 9 without allowing it to escape out of the inner insulating tube I I. This causes the cap 9 metallic tube I2, the remaining part of the fusible member 5 and the insulating tube II to be expelled to- 45 gether as a unit from the terminal piece 3, releasing the connection between the terminal piece 3 and resilient legs I0.

As in this invention there is provided the metallic tube I2 adapted for both supporting the 50 inner insulated cylinder II' and receiving pressure as described hereinbefore, it is possible to obtain such construction that the inner cylinder II' is easily supported concentrically with the fusible member 5 and the internal pressure iro- 55 That is to say, said tube I2 transmits the 40 duced in the inner cylinder II is made to act upon the cap ilv effectively. Thus, even in case of low or high voltage the expulsion due to the internal pressure is effected satisfactorily, so that the blowing of the fusible member is done quickly and accurately, especially when the device is used in connection with an electric current of a high voltage.

In the embodiments of the invention shown in Figs. 3 and 4, there is provided a transparent outer insulating cylinder I8 in which there is inserted one or more inner insulating cylinders 20 and 20 formed tubularly of a thin sheet such as a regenerated cellulose sheet (popularly known as cellophane), a fibreV coated with regenerated cellulose or a starchy sheet, for example, oblate. The inner insulating cylinder 20 is expanded by the internal pressure produced upon the formation of an arc in an arcing circuit provided in the inner cylinder and is shrunk axially by the high vacuum induced with the escape of the internal pressure, thereby pressing and dispersing the arc and thus increasing the current density of the unit arc and extinguishing it. To both ends of the outer insulating cylinder I8 there is engaged a metallic cap 22 which is united tightly to the outer cylinder I8 by a suitable binding agent, as indicated at 23. The said cap has va screw thread at its outer end portion and also has a central opening in said end. Also, there is screwed to the cap 22 a cap-shaped piece 24 which has an air outlet `25. A fusible member 2 I is mounted in the inner cylinder 20 in such a manner so that the fusible member does not contact with the cylinder. Both ends of this fusible member are bent to a Y orT-shape and the end portions of such Y-shaped portions are bent horizontally. Then, the bent horizontal end portions thus formed are inserted between the outer end of the cap 22 and cap-shaped piece 24. If the fusible member 2| or arcing circuit is disposed on the axial line of the insulating cylinder I8 and. is fused or broken, the temperature will bev raised'quickly owing to the formation of an arc 20 in an instant and presses the air or liquid bethe opening 25 immediately high vacuum is induced in the inner cylinder 20 by its reaction to shrink the cylinder 20 axially and rapidly as if it were to collapse the arc by tightening, and as the high temperature is lowered by having part of it absorbed by the inner wall of the inner cylinder, the effect of so-called surface deionization ls great. Thus, by applying pressure reactionally at the same time with the formation of an arc and absorbing its h eat energy the arc is quenched.

The burnt metallic powder produced upon the formation of an arc adheres to the inner Wall of the inner insulating cylinder, and not to the outer cylinder. Therefore, there is no apprehension of the insulation being reduced by the attachment of the metallic powder, and even when cutting off a high voltage current, the object of protecting the outer insulating cylinder by the above action is readily attained. Moreover, with a closed type of electric fuse device the desired action is found to be successful owing to the high vacuum created in the cylinder (at the time of fusing) without burning ven an inflammable object. If the inner cylinder 20 has a diameter the same or larger than the diameter of the air outlet 25 and is long enough to contact internally with the opening 25 or to reach the edge of the inner end of the cap 2 2, it can be expanded without interference by the internal pressure produced upon the formation of an arc shown`engaged in an enlarged intermediate portion of the outer insulating cylinder I8 to doubly protect said outer cylinder during the fusing of the fusible member.

Iclaim:

An electric fuse member comprising an outer cylinder of insulating material, tubular terminals of conducting material mounted on opposite ends of the cylinder, a fusible member disposed in said cylinder and electrically connected at its opposite ends with said terminal members, a flexible cylinder of insulating material disposed Within the outer cylinder and encircling said fusible member, said flexible cylinder being subject to expansion under pressure developed therein by the formation of an arc, and end-closing members carried by said terminals and adapted to permit escape of such pressure to cause the flexible cylinder to contract and thereby create a partial vacuum therein.

KENZO UTSUNOMIYA.

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