JPS634356Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a fuse that melts in oil and cuts out overcurrent.

[Prior art and its problems]

Conventionally, a general current limiting fuse containing an arc extinguishing agent sealed in a pressure-resistant container has been used as an oil-immersed fuse, but such fuses have the drawbacks of large external dimensions and high cost. Originally, if the capacitor melts in oil, the arc-extinguishing effect of the oil will work, so if this is used effectively, it should be possible to obtain better breakage and breakage characteristics than in air, but in the current range that slightly exceeds the rated current, The high energy of the arc generated when melting the fusible material decomposes the oil and generates conductive tar-like solid carbide, causing the inability to cut. This phenomenon often occurs particularly in high-pressure oil where oil flow is poor.

In order to eliminate such drawbacks and take advantage of the feature of arc extinguishing in oil, an oil-immersed fuse as shown in FIG. 1 is known. In FIG. 1, terminals 2 and 2' made of conductive metal fittings are attached to both ends of an insulating cylinder 1, and one end of the main fusible body 3 is fixed to one terminal 2'.
The other end is tensioned by a tension spring 4 made of a good conductor and fixed to the terminal 2'. The terminals 2 and 2' are provided with oil holes 5 to equalize the oil pressure inside and outside the insulating cylinder 1. This fusible body 3 is set to melt earlier than the tension spring 4 due to overcurrent.

This submerged fuse in oil is inserted into a warning circuit submerged in oil that is supposed to cut off overcurrent, and if an overcurrent exceeding the rating flows during energization, a part of the main fusible body 3 will melt and an arc will occur. do. Then, since the remaining part of the fuse is pulled away by the spring 4 in the direction of the arrow P, the arc becomes longer and the arc voltage gradually increases. Additionally, the surrounding oil vaporizes due to arc heat, rapidly cooling the arc and extinguishing it.

Such an oil-in-oil fuse has the drawback that, since tension is constantly applied to the main fusible body, the fusing characteristics of the main fusible body change over a long period of time, making it difficult to obtain high reliability. Furthermore, when applied to a fuse for large currents, it is difficult to energize the tension spring, and there are disadvantages in that it becomes complicated, such as providing a fusible member for a shunt.

[Purpose of invention]

The object of the present invention is to provide a high-flow rated submerged fuse that has stable shearing characteristics and a large shearing capacity in high-pressure oil.

[Key points of the idea]

In order to achieve this object, the present invention includes a main fusible body stretched between both terminals, a protruding piece attached to a holder and urged in the direction of the main fusible body by a spring, and a protruding piece and an auxiliary fusible body that is stretched between the terminals so as to prevent the pieces from flying out against the spring, and which melts later than the main fusible body, and the protruding pieces are caused by the melting of the auxiliary fusible body. Pressing and moving the main fusible body in a direction substantially perpendicular to the stretching direction thereof,
This is an oil-immersed fuse that extends the arc generated in the fused part of the main fusible body and uses the protruding piece to generate an oil flow in the fused part to quickly extinguish the arc.

[Example of idea]

Embodiments of the present invention will be described in detail below with reference to the drawings shown in FIGS. 2 and 3. In Fig. 2, terminals 2 and 2' made of conductive metal fittings with oil holes 5 provided at both ends of the insulating cylinder 1 are attached, as in the conventional case, and there is a narrow part 3a in the middle.
It is also the same as an ordinary fuse in that the main fusible body 3 provided with the fuse is stretched between the terminals 2 and 2'. However, in addition to this, when the main fusible body 3 is fused, the submerged oil fuse has a projecting piece 6 that presses and moves the main fusible body 3 in a direction approximately perpendicular to the direction in which it is stretched, as shown in FIG. 3A.
It is provided as shown in . In FIG. 3A, the projecting piece 6 is formed into a cylindrical shape with a bottom, and a compression spring 7 is disposed inside. This protruding piece 6
is a connecting piece 8 fixed to the inside of the terminals 2 and 2';
A mounting base 9 stretched between the connecting pieces 8,
It is restrained by a holder 11 consisting of a guide 10 fixed to a mounting base 9. To explain in more detail,
The projecting piece 6 is inserted into a guide 10 together with a compression spring 7, and is drawn to the mounting base 9 against the spring 6 by an auxiliary fusible body 12 that passes through a hole at the bottom of the projecting piece 6. Both ends of the auxiliary fusible body 12 are tightened by screws 13 that connect the connecting piece 8 and the mounting base 9 to establish an electrical connection and to prevent the protruding piece 6 from moving.

When this submerged fuse is inserted into a warning circuit submerged in oil that is supposed to cut off an overcurrent and a large current exceeding the rating flows while it is energized, the narrow part 3a of the main fusible body 3 will first fuse, causing an arc. Occur. Then, a part of the current in the main fusible body 3 is transferred to the auxiliary fusible body 12, so that the auxiliary fusible body 12 is also fused, and the protruding piece 6 is caused by the bias of the compression spring 7, which was restrained by the auxiliary fusible body 12. The main fusible body 3 that has protruded along the guide 10 and is fused at the narrow part as shown in FIG. 3B is pressed and moved in the direction of the insulating cylinder 1 as indicated by the Q arrow. Therefore, the interval between the fused portions of the main fusible body 3 becomes wider, the arc becomes longer, and the arc voltage becomes higher. Also, at this time, the protruding piece 6 and the main fusible body 3 push the surrounding oil in the direction of the arrow Q, creating an oil flow near the melting arc point, new oil flowing into the arcing point, and the arc being cooled. Arc quickly extinguishes. At this time, the carbide is also washed away, and the harm caused by the carbide is also removed.

[Effect of idea]

As described above, in the oil-immersed fuse according to the present invention, when the main fusible body is blown, the auxiliary fusible body that was suppressing the flying pieces also blows out, and the flying pieces fly out and destroy the main fusible body. Press and move it in a direction perpendicular to the direction in which it is stretched. As a result, the arc generated at the melting point of the main fusible material becomes longer, the arc voltage increases, and at the same time an oil flow is generated due to the movement of the flying pieces and the main fusible material, new oil comes into contact with the arc, cools the arc, and quickly Extinguish the arc. At this time, the carbide is washed away by the oil flow, so there is no accumulation of carbide. Therefore, this oil-immersed fuse is small and can provide excellent shearing characteristics.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of a conventional submerged fuse in oil, Fig. 2 is a sectional view showing an embodiment of an submerged fuse in oil according to the present invention, and Fig. 3A is a support for the projecting piece shown in Fig. 2. FIG. 3B is an enlarged cross-sectional view showing the structure, and FIG. 3B is a cross-sectional view showing the operation of the ejecting piece of FIG. 2, 2'... Terminal of fuse in oil, 3... Main fusible body, 6... Projection piece, 7... Compression spring, 11...
Holder for projecting pieces, 12...auxiliary fusible body.

Claims (1)

[Scope of utility model registration request] A main fusible body stretched between both terminals, a protruding piece attached to a holder and urged in the direction of the main fusible body by a spring, and a protruding piece of the protruding piece against the spring. an auxiliary fusible body stretched between the terminals so as to inhibit the main fusible body from fusing later than the main fusible body; A submerged oil fuse characterized by being pressed and moved in a right angle direction.