JP7383658B2 - Fuse for high pressure blower - Google Patents

Description

This specification discloses a technology related to a fuse for a high-pressure blower.

In order to prevent excessive current from flowing into high voltage equipment such as transformers, high voltage fuses are placed between power distribution lines and high voltage equipment. Patent Document 1 discloses a high-voltage fuser (including an upper electrode connected to a power distribution line, a lower electrode connected to wiring on a high-voltage equipment side, and a high-voltage fuser disposed between the upper electrode and the lower electrode). A cylindrical cutout) is disclosed. The fuse for a high-voltage blower disclosed in Patent Document 1 has a head fitting connected to an upper electrode, a lower connecting line connected to a lower electrode, and a fusible wire connected between the head fitting and the lower connecting line. It includes a connecting wire and a cylindrical arc-extinguishing tube surrounding the fusible connecting wire. The fusible connection wire consists of a support plug (sealing member) on the head metal side, a support plug (sealing member) on the lower connection line (connection member that connects the lower connection wire to the fusible connection wire), and an arc extinguishing tube. Located in a closed space surrounded by The arc extinguishing tube generates arc extinguishing gas in a sealed space to extinguish the arc when the fusible connection wire melts and an arc is generated. In Patent Document 1, the arc extinguishing tube is fixed to the head metal fitting by adhesive.

JP2020-61334A

As described above, the arc generated by the melting of the fusible connection wire is extinguished by the arc extinguishing gas generated in the sealed space. At this time, if the pressure of the arc extinguishing gas in the closed space is insufficient, it becomes difficult to extinguish the arc. On the other hand, if the pressure of the arc extinguishing gas in a closed space is too high, the arc can be extinguished, but the arc extinguishing tube may be damaged due to the pressure of the arc extinguishing gas, and in some cases, the arc extinguishing tube may be There is also a risk of damaging the fuse tube. If the arc extinguishing tube is configured so that when the pressure of the arc extinguishing gas in the enclosed space reaches a predetermined value, the volume in the enclosed space increases and the arc extinguishing tube comes off from the head fitting, damage to the arc extinguishing tube can be prevented. can. However, in the high-pressure fuse of Patent Document 1, since the arc-extinguishing tube is fixed to the head fitting by adhesive, it is difficult to set and control the pressure at which the arc-extinguishing tube comes off from the head fitting. SUMMARY OF THE INVENTION It is an object of the present specification to provide a novel high pressure fuse that can set and control the pressure at which the arc extinguishing tube is disengaged from the head fitting.

The fuse for a high-voltage blower disclosed herein is arranged between an upper electrode and a lower electrode in a high-pressure blower having an upper electrode connected to a power distribution line and a lower electrode connected to wiring on a high-voltage equipment side. Ru. This high-voltage blower fuse consists of a head metal fitting connected to the upper electrode, a lower connection line connected to the lower electrode, a fusible connection line connected between the head metal fitting and the lower connection line, and a fusible A cylindrical arc-extinguishing tube surrounding the connection wire is provided. The head metal fitting has a head portion and a columnar portion. The head portion is located outside the arc extinguishing tube. The columnar portion extends from the head portion into the arc extinguishing tube. In this fuse for a high-pressure blower, an internal pressure adjusting member is fixed to a columnar portion within the arc-extinguishing tube. Further, in this fuse for a high-pressure fuse, the arc extinguishing tube is fixed to the head fitting by the internal pressure adjusting member.

A cross-sectional view of a high-pressure fuser is shown. A half-sectional view of the fuse of the first embodiment is shown. A cross-sectional view of the main structure of the fuse is shown. A cross-sectional view of the head fitting and arc extinguishing tube is shown. An enlarged sectional view of the fixed portion of the head fitting and the arc extinguishing tube is shown. The top view of the internal pressure adjustment member used for fixing a head fitting and an arc extinguishing tube is shown. A sectional view of both the arc extinguishing tube and the head metal fitting is shown. An enlarged cross-sectional view of both fixed parts in a state where the arc extinguishing tube is removed from the head fitting is shown. A sectional view of the head metal fitting and the arc extinguishing tube of the fuse of the second embodiment is shown. A sectional view of the head metal fitting and the arc extinguishing tube of the fuse of the third embodiment is shown.

(High pressure fuser)
A high-voltage fuser is connected between a power distribution line and a high-voltage device such as a transformer via an external electric wire. A high-voltage fuser consists of a cylindrical body insulator made of porcelain, an upper electrode connected to the distribution line, a lower electrode connected to the wiring on the high-voltage equipment side, and a high-voltage fuser placed between the upper electrode and the lower electrode. Equipped with a fuse for the blower. The upper electrode, lower electrode, and high-voltage blower fuse are arranged within the main body insulator. If an excessive current (a current higher than the specified value) flows through the high-voltage fuse (fuse for high-voltage fuse), the element (fusible connection wire) of the fuse for the high-voltage fuse will melt, causing the power distribution line between the distribution line and the high-voltage equipment to melt. is blocked. Note that when the element of the high-pressure blower fuse blows out, the power distribution line and the device can be reconnected by replacing the high-pressure blower fuse.

(Fuse for high pressure blower)
A fuse for a high-pressure blower includes a head fitting, a lower connecting wire, a fusible connecting wire, and an arc extinguishing tube. A metal upper contact is fixed to the upper part of the fuse cylinder, and a metal lower contact is attached to the lower part of the fuse cylinder. The fuse cylinder is formed of a cylindrical insulating material. Therefore, the upper contact and the lower contact are insulated by the fuse tube. The head fitting, the lower connecting wire, the fusible connecting wire, and the arc extinguishing tube are arranged within the fuse tube. The head fitting is connected to the upper electrode via the upper contact. The lower connection line is connected to the lower electrode via the lower contact. The fusible connection line is surrounded by the arc-extinguishing tube and is connected to the head fitting and the lower connection line between the two. The head fitting and the lower connecting wire (upper contact and lower contact) are not directly electrically connected, but are electrically connected through a fusible connecting wire. The fusible connecting wire is made of a low melting point metal. As the material for the fusible connection wire, tin alone or an alloy mainly composed of tin (nickel-tin alloy, tin-silver alloy, copper-tin alloy, tin-silver-copper alloy, etc.) can be used. Note that the fusible connection wire is preferably formed of a metal that does not contain lead.

The head fitting has a head portion having an outer size larger than the inner diameter of the arc extinguishing tube, and a columnar portion extending from the head portion into the arc extinguishing tube and having an outer diameter smaller than or equal to the inner diameter of the arc extinguishing tube. The columnar portion is inserted into the arc extinguishing tube and loosely fits into the arc extinguishing tube. That is, the arc-extinguishing tube is inserted through the columnar part. When the columnar portion is inserted into the arc-extinguishing tube, the head portion is located outside the arc-extinguishing tube and the columnar portion extends inside the arc-extinguishing tube. In the head fitting, the head part and the columnar part may be integrated (one piece that cannot be separated), or the head part and the columnar part may be fixed to each other as separate parts. Note that the head portion may have a size that cannot be inserted into the arc extinguishing tube, and its shape is not particularly limited, and may be circular, polygonal, etc., for example.

The arc extinguishing tube can be formed by winding kraft paper or the like. By adjusting the number of turns of the kraft paper, the inner diameter and outer diameter of the arc extinguishing tube can be adjusted. The arc extinguishing tube has a small diameter portion having an inner diameter smaller than other portions, and a large diameter portion having an inner diameter larger than the small diameter portion. The small diameter portion is provided at the head portion side end portion. The columnar part of the head fitting passes through the small diameter part and extends to the large diameter part. In addition, in the boundary part of a small diameter part and a large diameter part of an arc extinguishing tube, a notch part may be provided in the inner peripheral surface of a small diameter part. That is, a notch that substantially increases the inner diameter of the small diameter portion may be provided at the end of the small diameter portion on the large diameter portion side. The notch may have a tapered shape in which the notch amount continuously increases (inner diameter substantially increases) toward the large diameter portion, or may have a stepped shape in which the notch amount increases discontinuously (steps). ). Note that the arc extinguishing tube (small diameter portion and large diameter portion) may be formed in one piece. Alternatively, the small diameter portion may be a cylindrical body separate from the arc extinguishing tube (large diameter portion) on the inner peripheral surface of an arc extinguishing tube with a uniform inner diameter (that is, an arc extinguishing tube with a large diameter portion from one end to the other end). It may be formed by fixing. By forming the arc extinguishing tube using cylinders of different diameters, the inner diameter within the arc extinguishing tube can be easily changed (forming a small diameter portion and a large diameter portion).

The arc extinguishing tube is positioned (attached) to the head fitting using the small diameter portion. Specifically, within the arc extinguishing tube, a ring-shaped internal pressure adjusting member is fixed to the columnar part of the head fitting. The internal pressure adjusting member may be ring-shaped and have an outer size larger than the inner diameter of the small diameter portion and smaller than the inner diameter of the large diameter portion. The internal pressure adjusting member is press-fitted and fixed to the columnar portion in a state in which the columnar portion of the head fitting is inserted into the arc extinguishing tube (a state in which the columnar portion passes through the small diameter portion). When the internal pressure adjusting member is fixed to the columnar portion, the small diameter portion is arranged between the head portion of the head fitting and the internal pressure adjusting member. By fixing the internal pressure adjusting member to the columnar part, movement of the arc extinguishing tube in the axial direction is restricted by the head part and the internal pressure adjusting member, and the arc extinguishing tube is positioned with respect to the head fitting. That is, the arc extinguishing tube is attached to the head metal fitting without being fixed to the head metal fitting by adhesive. The inner peripheral portion of the internal pressure adjusting member may be in contact with the entire circumference of the columnar portion, or may be in contact with a portion of the columnar portion in the circumferential direction (for example, intermittently in the circumferential direction).

When the internal pressure adjusting member is press-fitted and fixed to the columnar portion, the inner circumferential portion of the internal pressure adjusting member is deformed, and the internal pressure adjusting member is fixed to the columnar portion with the inner circumferential portion bent in a direction away from the head portion. If the inner circumference of the internal pressure adjustment member is bent away from the head and fixed to the columnar part, the internal pressure will not be adjusted under normal conditions (no overcurrent flowing through the high-pressure blower fuse). Even if the small diameter portion of the arc extinguishing tube contacts the member (even if the arc extinguishing tube attempts to move away from the head portion of the head fitting), the position of the internal pressure adjusting member relative to the columnar portion does not change. That is, the arc extinguishing tube will not come off from the head fitting. The internal pressure adjusting member may be made of metal. The inner circumference of the metal internal pressure adjusting member is easily deformed (plastically deformed) when it is press-fitted into the columnar part, and the inner circumference can be easily bent away from the head. An example of a metal internal pressure adjusting member is a metal washer.

Although details will be described later, in the fuse for a high-pressure blower disclosed in this specification, when an overcurrent is applied to the fuse for a high-pressure blower, the arc extinguishing tube moves downward relative to the head fitting. There is. When the arc extinguishing tube moves downward (actually, the arc extinguishing tube moves away from the head), the inner peripheral portion of the internal pressure adjustment member changes from being bent away from the head to bending away from the head. It changes to a state where it is bent in the direction towards the part. In particular, if the interior of the internal pressure adjustment member is a metal washer, the direction of bending of the inner peripheral portion is likely to be changed (plastically deformed) from a direction away from the head section to a direction toward the head section. By adjusting the contact area between the inner circumferential portion of the pressure adjusting member and the columnar portion and/or the thickness of the inner pressure adjusting member, it is possible to adjust the force at which the direction of bending of the inner circumferential portion begins to change. The inner peripheral portion of the internal pressure adjustment member may be provided with a protrusion that protrudes toward the center in the radial direction. In this case, the plurality of protrusions may be provided at equal intervals in the circumferential direction. By adjusting the number of protrusions and the gap between the protrusions, it is possible to adjust the force at which the direction of bending of the inner peripheral portion begins to change.

As mentioned above, the fusible connecting line is connected between the head fitting and the lower connecting line. That is, the fusible connection line is fixed to both the head fitting and the lower connection line. Specifically, one end of the fusible connection wire is directly fixed to the head metal fitting, and the other end of the fusible connection wire is fixed to the lower connection line via a fastening metal fitting. In addition, in the fuse for a high-pressure blower, a tensile wire is fixed to the head metal fitting and the fastening metal fitting in addition to the fusible connecting wire. The tensile wire functions as a resistor. As the material for the tensile wire, stainless steel, elemental silver, elemental copper, copper alloys mainly composed of copper (copper-nickel alloys, copper-nickel-chromium alloys), etc. can be used. In the fuse for a high-pressure fuse, the columnar part of the head fitting is provided with an upper sealing member that closes the gap between the columnar part and the arc-extinguishing tube, and a lower sealing member that closes the gap between the fastening fitting and the arc-extinguishing tube. As a result, the fusible connection wire is placed in a sealed space surrounded by the upper sealing member, the lower sealing member, and the arc-extinguishing tube (large diameter portion).

In the fuse for a high-voltage blower, when an overcurrent (a current higher than a specified value) flows through the fusible connecting wire, the fusible connecting wire melts and the tensile wire is cut. When the fusible connection wire is fused, arc-extinguishing gas is generated from the inner surface of the arc-extinguishing tube due to the heat generated during the fusion. The arc-extinguishing gas generated from the arc-extinguishing tube fills the sealed space, increases the pressure within the sealed space, and extinguishes the arc generated during the melting. When the fusible connection wire is fused, the lower sealing member moves downward due to the increased pressure in the sealed space, and protrudes from the lower end of the fuse cylinder together with the lower connection wire.

When the pressure within the sealed space rises excessively, the volume within the sealed space rapidly increases, causing the lower sealing member to move downward and also applying a downward force to the arc extinguishing tube. In the fuse for a high-pressure fuse disclosed herein, when the pressure in the sealed space rises above a specified value, the arc extinguishing tube moves slightly downward with respect to the head fitting, and the small diameter part of the arc extinguishing tube Move the adjustment member downward. As a result, a force that causes the arc extinguishing tube to move the internal pressure adjusting member downward is applied to the outer circumferential portion of the internal pressure adjusting member, and the inner circumferential portion of the internal pressure adjusting member is bent toward the head portion of the head fitting. When the inner peripheral part of the internal pressure adjustment member bends toward the head, the arc extinguishing tube will bend against the head fitting even if the force is relatively weak (the pressure in the sealed space is lower than the specified value). Can be moved downwards. By easily moving the arc extinguishing tube downward with respect to the head fitting, the volume within the sealed space increases at an early stage, and the pressure within the sealed space is reduced. That is, the internal pressure of the closed space is adjusted by the internal pressure adjusting member. Note that if the arc extinguishing tube further moves downward with respect to the head fitting due to the pressure within the sealed space, the arc extinguishing tube will come off from the head fitting and the pressure within the sealed space will become equal to the pressure outside the sealed space. That is, the sealed space is no longer in a sealed state, and the pressure within the sealed space is reduced to the same level as the pressure within the fuse cylinder. As a result, there is no possibility that the fuse cylinder will be damaged. The force (pressure) that causes the inner circumferential surface of the internal pressure adjusting member to change from being bent downward (away from the head) to being bent upward (towards the head) was determined by experiment. This can be determined in advance.

As described above, the end portion of the small diameter portion of the arc extinguishing tube on the large diameter portion side may be provided with a notch portion that substantially increases the inner diameter of the small diameter portion. If the small diameter portion is provided with a notch, when the inner peripheral portion of the internal pressure adjusting member is bent upward, the bent portion can be located within the notch. That is, the bent portion of the internal pressure adjusting member can be prevented from coming into contact with the arc extinguishing tube (small diameter portion). By preventing contact between the bent portion and the arc extinguishing tube, it is possible to suppress the change in direction of the bent portion from being inhibited by the arc extinguishing tube. When the pressure in the sealed space exceeds a predetermined value, the direction of the bent part changes reliably, the volume in the closed space increases, and the pressure in the closed space can be reliably reduced, which in turn leads to The arc tube can be securely removed from the head fitting.

(High pressure fuser)
Referring to FIG. 1, the high pressure fuser 100 will be described. The high voltage fuser 100 is provided on a power distribution line and is used to protect high voltage equipment such as a transformer. The high-pressure fuser 100 includes a main body insulator 8 made of porcelain, an upper electrode 56 connected to the power distribution line side, an arc extinguishing rod 54 arranged inside the upper electrode 56, and a lower electrode 46 connected to the equipment side. and a fuse 12 connecting the upper electrode 56 and the lower electrode 46. The main body insulator 8 has a cylindrical shape, and a plurality of insulating folds 14 are provided on the outer peripheral surface. A cylindrical first chamber 4 and a cylindrical second chamber 20 having a larger diameter than the first chamber 4 are formed within the main insulator 8 . A cylindrical arc extinguishing tube 6 is arranged within the first chamber 4. The fuse 12 is arranged inside the arc extinguishing cylinder 6. The high-pressure fuser 100 is installed so that the first chamber 4 is on the upper side and the second chamber 20 is on the lower side in the direction of gravity. The upper electrode 56 is arranged in the first chamber 4 and the lower electrode 46 is arranged in the second chamber 20.

A conical upper mold cone 2 is fixed to the upper part of the main body insulator 8 with an adhesive. The lead wire of the upper mold cone 2 is connected to a power distribution line. A conical lower mold cone 28 is fixed to the lower side wall 24 of the main insulator 8 with adhesive. The lead wire of the lower mold cone 28 is connected to equipment such as a transformer.

The fuse 12 extends from the first chamber 4 to the second chamber 20 and connects the upper electrode 56 and the lower electrode 46. The fuse 12 includes an insulating fuse tube 50, an upper contact 52 provided at the top of the fuse tube 50, a lower contact 48 provided at the bottom of the fuse tube 50, and a lower contact 48 than the lower contact 48. It includes a display tube 58 provided below. Upper contact 52 is connected to upper electrode 56 and lower contact 48 is connected to lower electrode 46. A buffer member 18 is arranged between the lower contactor 48 and the upper surface of the second chamber. The display tube 58 is fixed to the fuse tube 50. On the other hand, the lower contactor 48 is vertically movable with respect to the fuse tube 50 and the display tube 58. The display tube 58 constitutes the lower end of the fuse 12.

Although details will be described later, a head metal fitting 70, a fusible connecting wire 80, and a lower connecting wire 90 are accommodated in the fuse tube 50. The lower connection wire 90 is taken out from the lower end of the display tube 58 to the outside of the fuse tube 50, is folded back upward at the lower end of the display tube 58, and is tightened and fixed to the tightening screw 60 attached to the lower contactor 48. ing. Note that a spring 44 is disposed in a compressed state between the lower contactor 48 and the display cylinder 58. Therefore, a tensile force is applied to the lower connection line 90. In other words, by tightening and fixing the lower connecting wire 90 to the tightening screw 60, the spring 44 is compressed.

An opening 38 is provided at the lower end of the main insulator 8 (lower end of the second chamber 20). The opening 38 is closed by the lid member 34. The lid member 34 is fixed to the inner wall 30 of the second chamber 20 with an adhesive 36. The lid member 34 has a cylindrical shape with a bottom, and includes a shaft portion 34a, a flange portion 34b provided on the outer peripheral surface of the shaft portion 34a, and an opening/closing portion (bottom portion) provided on the inner peripheral surface of the shaft portion 34a. It is equipped with 32. The collar portion 34b is provided at a vertically intermediate portion of the shaft portion 34a, protrudes radially outward, and goes around the outer periphery of the shaft portion 34a. The opening/closing part 32 is provided below the collar part 34b and above the lower end of the shaft part 34a. Therefore, the lower end of the shaft portion 34a forms a protrusion 34c that protrudes downward with respect to the opening/closing portion 32. The opening/closing part 32 is protected by the protrusion 34c. Note that the lid member 34 (including the opening/closing part 32) is made of an elastic material such as flame-retardant rubber or soft synthetic resin.

The opening/closing portion 32 is provided with radial notches 32a. Therefore, the fuse 12 and the like can easily pass through the opening/closing section 32. That is, when the fuse 12 etc. pass through the opening/closing part 32, the opening/closing part 32 is deformed and the opening/closing part 32 opens, and after the fuse 12 etc. passes, it returns to its original shape and the opening/closing part 32 closes. As described above, since the opening/closing part 32 (lid member 34) is formed of an elastic material, it is easily deformed (elastically deformed) by providing the cut 32a, and the lid member 34 can be opened and closed.

In the high-voltage fuser 100, when a current exceeding a specified value flows through the fuse 12, the fusible connection wire 80 within the fuse 12 is blown. As a result, the spring 44 expands, and the fuse 12 (components other than the lower contact 48), including the fuse tube 50, moves downward while the lower contact 48 remains connected to the lower electrode 46. After the fuse tube 50 (fuse 12) moves downward due to the elastic force of the spring 44 and gravity, the stepped portion 50a formed on the fuse tube 50 contacts the spring 45 disposed on the upper contact 52 side of the lower contact 48. (See Figure 2). The downward movement of the fuse tube 50 is damped, and the movement of the fuse tube 50 is stopped. When the fuse 12 moves downward, the display cylinder 58 is exposed to the lower part of the high-pressure fuser 100 from the lid member 34 (opening/closing part 32). That is, by checking whether or not the display tube 58 is exposed at the bottom of the high-pressure fuser 100, it is possible to determine whether or not the fusible connection wire 80 is blown (or whether or not it is necessary to replace the fuse 12). . Note that even if the fusible connection wire 80 is fused, the lower contactor 48 continues to be connected (fixed) to the lower electrode 46. Therefore, the fuse 12 (display cylinder 58) is prevented from falling from the high-pressure fuser 100.

(Fuse: 1st example)
The fuse 12 will be explained with reference to FIGS. 2 to 6. As shown in FIG. 2, an upper contact 52 is fixed to the upper part of the fuse cylinder 50. The upper contact 52 is screwed into the fuse tube 50. An uneven surface 52a is formed on a part of the surface of the upper contactor 52. By providing the uneven surface 52a, when the upper contact 52 is screwed into the fuse cylinder 50, slipping of the upper contact 52 can be suppressed, and the upper contact 52 is securely fixed to the fuse cylinder 50. can do. The lower portion of the fuse tube 50 extends into the lower contact 48 . An arc extinguishing tube 85 is disposed within the fuse cylinder 50. At the upper end of the arc-extinguishing tube 85, a head portion 70a of the head fitting 70 is provided outside the arc-extinguishing tube 85. The head portion 70a is in contact with the upper contactor 52. That is, the head metal fitting 70 is connected to the upper electrode 56 via the upper contact 52 (see also FIG. 1).

A lower connection line 90 appears from the lower end of the arc extinguishing tube 85 to the outside of the arc extinguishing tube 85 and from the lower end of the display tube 58 to the outside of the fuse 12 . A connecting terminal 90a is fixed to the end of the lower connecting wire 90, and the connecting terminal 90a is fixed to the tightening screw 60 (lower contact 48). That is, the lower connection line 90 is connected to the lower electrode 46 via the lower contact 48 (see also FIG. 1).

FIG. 3 shows the internal structure of the arc extinguishing tube 85. As shown in FIG. 3, the head metal fitting 70 includes a head portion 70a and a columnar portion 70b. The head portion 70a is provided at one end (upper end) of the columnar portion 70b. In other words, the columnar portion 70b extends in one direction from the head portion 70a. The head portion 70a is disc-shaped and has an outer diameter larger than the outer diameter of the arc-extinguishing tube 85. Since the outer diameter of the head portion 70 a is larger than the inner diameter of the arc extinguishing tube 85 , the head portion 70 a is located outside the arc extinguishing tube 85 on the upper side of the arc extinguishing tube 85 . The columnar portion 70b extends downward into the arc extinguishing tube 85 from the head portion 70a. An upper sealing member 74 is adhesively fixed to the lower end of the columnar portion 70b. In addition, the upper sealing member 74 and the columnar part 70b may be fixed by fitting the upper sealing member 74 into the columnar part 70b so as to cover the lower end of the columnar part 70b. The upper sealing member 74 has a disc shape, and its outer peripheral surface is in contact with the inner peripheral surface of the arc extinguishing tube 85 . The upper sealing member 74 closes the gap between the columnar part 70b and the arc extinguishing tube 85.

A fusible connecting wire 80 and a tensile wire 82 are fixed to the lower portion of the columnar portion 70b. Therefore, the sides of the fusible connection wire 80 and the tensile wire 82 are surrounded by the arc-extinguishing tube 85. Further, the fusible connecting wire 80 and the tensile wire 82 are also fixed to a fastening fitting 92. In other words, one end of the fusible connecting wire 80 and the tensile wire 82 is fixed to the columnar part 70b (head fitting 70), and the other end is fixed to the fastening fitting 92. A lower connection line 90 having a connection terminal 90a is further fixed to the fastening fitting 92. The fusible connection wire 80 and the tensile wire 82 are connected to both the columnar part 70b (head metal fitting 70) and the lower connection line 90 via a fastening metal fitting 92.

A lower sealing member 94 is adhesively fixed to the upper end of the fastening fitting 92 . The lower sealing member 94 has a disc shape, and its outer peripheral surface is in contact with the inner peripheral surface of the arc extinguishing tube 85 . The lower sealing member 94 closes the gap between the fastening fitting 92 and the arc extinguishing tube 85. In the vertical direction, the lower sealing member 94 is provided at a position apart from the upper sealing member 74. Therefore, the fusible connection wire 80 and the tensile wire 82 are present in a sealed space 84 surrounded by the upper sealing member 74, the lower sealing member 94, and the arc-extinguishing tube 85.

Note that a spring washer 72 is attached to the upper end (outer periphery of the upper end portion) of the arc extinguishing tube 85. The spring washer 72 is an example of a metal washer (internal pressure adjustment member). The spring washer 72 is fitted into a recess (not shown) provided on the outer peripheral surface of the upper end portion of the arc extinguishing tube 85 and is positioned relative to the arc extinguishing tube 85. The spring washer 72 is in contact with the lower surface of the head portion 70a of the head fitting 70. Therefore, as shown in FIG. 2, when the arc extinguishing tube 85 is attached to the fuse tube 50, the spring washer 72 presses the head portion 70a against the upper contact 52, ensuring that the head portion 70a and the upper contact 52 are electrically connected. The upper electrode 56 and the lower electrode 46 are reliably electrically connected (see also FIG. 1).

FIG. 4 shows an enlarged view of the upper end portion of the arc extinguishing tube 85. As shown in FIG. 4, the arc extinguishing tube 85 includes a small diameter portion 85a and a large diameter portion 85b. The small diameter portion 85a is provided at the end (upper end portion) on the head portion 70a side. From one end to the other end of the arc extinguishing tube 85, the small diameter portion 85a has an inner diameter smaller than the other portions (see also FIG. 3). In the arc extinguishing tube 85, all portions other than the small diameter portion 85a are formed to have the same inner diameter (inner diameter is larger than the small diameter portion 85a). That is, in the arc extinguishing tube 85, all portions other than the small diameter portion 85a are large diameter portions 85b. Further, the columnar portion 70b of the head fitting 70 is inserted through the upper end of the small diameter portion 85a of the arc extinguishing tube 85, and the washer 76 is press-fitted and fixed to the columnar portion 70b at the step at the boundary between the small diameter portion 85a and the large diameter portion 85b. has been done. Note that since the columnar portion 70b is inserted into the small diameter portion 85a and the washer 76 is fixed to the columnar portion 70b, the arc-extinguishing tube 85 is rotatable with respect to the head fitting 70. Note that the outer circumferential surface of the columnar portion 70b and the inner circumferential surface of the small diameter portion 85a may be fixed by adhesive or the like. The washer 76 is ring-shaped and has a circular outer periphery. The outer diameter of the washer 76 is larger than the inner diameter of the small diameter portion 85a and smaller than the inner diameter of the large diameter portion 85b. Therefore, the surface of washer 76 (upper surface) faces the surface of small diameter portion 85a (lower surface).

As described above, on the upper side of the arc extinguishing tube 85, the head portion 70a is located outside the arc extinguishing tube 85 (outside the small diameter portion 85a). Further, the upper surface of the washer 76 faces the lower surface of the small diameter portion 85a. More specifically, the upper surface of the washer 76 is in contact with the lower surface of the small diameter portion 85a. Therefore, the small diameter portion 85a is arranged between the head portion 70a and the washer 76 in the vertical direction. The arc extinguishing tube 85 is positioned (fixed) on the head fitting 70 by disposing the small diameter portion 85a between the head portion 70a and the washer 76.

FIG. 5 shows an enlarged view of the boundary between the small diameter portion 85a and the large diameter portion 85b. As shown in FIG. 5, at the boundary between the small diameter portion 85a and the large diameter portion 85b, a notch 85c is formed at a corner of the small diameter portion 85a (the corner between the inner peripheral surface and the lower surface). The notch portion 85c goes around the small diameter portion 85a in the circumferential direction, and the amount of the cutout continuously increases toward the large diameter portion 85b side (lower side). In other words, a tapered notch 85c is provided at the lower end of the small diameter portion 85a so as to go around in the circumferential direction. Note that the notch portion 85c is formed in a size that prevents the inner peripheral portion 76a from coming into contact with the notch portion 85c even if the inner peripheral portion 76a of the washer 76, which will be described later, is bent upward.

The washer 76 has an inner peripheral portion 76a bent downward (in a direction away from the head portion 70a). As described above, the washer 76 is press-fitted into the columnar portion 70b. Specifically, the washer 76 is press-fitted from the lower end of the columnar portion 70b upward (toward the head portion 70a side). Therefore, the inner peripheral portion 76a of the washer 76 is bent downward due to friction with the columnar portion 70b. Since the inner peripheral portion 76a is bent downward, the small diameter portion 85a can be reliably supported, and the position of the arc extinguishing tube 85 relative to the head fitting 70 can be prevented from changing. That is, the arc extinguishing tube 85 is firmly fixed to the head fitting 70.

As shown in FIG. 6, the inner peripheral portion 76a of the washer 76 is provided with a plurality of protrusions 78 that protrude toward the center 76c. The respective protrusions 78 are provided at equal intervals in the circumferential direction of the washer 76. When the washer 76 is press-fitted into the columnar part 70b, all the protrusions 78 are bent downward.

The advantages of the fuse 12 will be explained with reference to FIGS. 7 and 8. As described above, when a current exceeding a specified value flows through the fuse 12, the fusible connection wire 80 is blown out. When the fusible connection wire 80 is fused, arc-extinguishing gas is generated from the inner surface of the arc-extinguishing tube 85, filling the sealed space 84 with the arc-extinguishing gas, and extinguishing the arc generated during the fusion. When the sealed space 84 is filled with arc-extinguishing gas, the pressure inside the sealed space 84 increases. As described above, since the inner peripheral portion 76a of the washer 76 is bent downward, the head fitting 70 and the arc extinguishing tube 85 are firmly fixed. Therefore, even if the pressure within the sealed space 84 increases, the position of the arc extinguishing tube 85 relative to the head fitting 70 does not change until the pressure reaches a predetermined level. Since the volume within the sealed space 84 does not change, the pressure within the sealed space 84 is likely to rise, and the arc generated during the melting can be reliably extinguished.

When the pressure within the sealed space 84 rises excessively (above a predetermined pressure), the volume within the sealed space 84 increases, and the arc extinguishing tube 85 moves downward with respect to the head fitting 70 (FIG. 7). When the arc extinguishing tube 85 moves downward, the lower surface of the small diameter portion 85a is in contact with the washer 76, so the washer 76 is moved downward. At this time, a force that moves the arc extinguishing tube 85 downward is applied to the outer circumferential portion of the washer 76, and the outer circumferential portion of the washer 76 is pushed down. As a result, the inner circumferential portion 76a of the washer 76 changes from a downwardly bent state (FIG. 5) to an upwardly bent state (FIG. 8). When the inner peripheral portion 76a of the washer 76 is bent upward, the washer 76 can be moved downward even under relatively weak pressure (less than a predetermined pressure). That is, when the pressure in the sealed space 84 rises to a predetermined pressure or higher and the inner circumferential portion 76a of the washer 76 is bent upward, the arc extinguishing tube 85 becomes easier to move downward. By moving the arc extinguishing tube 85 downward under this relatively weak pressure, the volume within the sealed space 84 increases at an early stage, and the pressure within the sealed space 84 can be reduced. Note that if the arc extinguishing tube 85 is further moved downward relative to the head fitting 70 due to the pressure in the sealed space 84, the arc extinguishing tube 85 will come off from the head fitting 70, and the pressure in the sealed space 84 will be reduced to the closed space. 84 outside (outside the arc extinguishing tube 85). That is, the sealed space 84 is no longer in a sealed state, and the pressure within the sealed space 84 decreases to the same level as the pressure within the fuse cylinder 50 (see also FIG. 2). The pressure in the sealed space 84 is suppressed from further rising beyond the predetermined pressure, and there is no fear that the fuse cylinder 50 will be damaged.

The fuse 12 utilizes the phenomenon in which the direction of bending of the inner circumferential portion 76a of the washer 76 changes, and when an overcurrent flows through the fuse 12, the arc extinguishing tube 85 tends to move downward. The volume can be increased quickly and the pressure within the closed space 84 can be reduced. Note that since the notch 85c is formed in the small diameter portion 85a, the inner peripheral portion 76a of the washer 76 is not in contact with the small diameter portion 85a. By providing the notch 85c in the small diameter portion 85a, it is possible to prevent the inner circumferential portion 76a from bending upward.

(Second example)
The fuse 112 will be explained with reference to FIG. The fuse 112 is a modification of the fuse 12, and the structure of the arc extinguishing tube 185 is different from the structure of the arc extinguishing tube 85 used in the fuse 12. Regarding the fuse 112, the same parts as the fuse 12 are given the same reference numbers as those given to the fuse 12, and a description thereof will be omitted.

The arc extinguishing tube 185 includes a small diameter portion 185a and a large diameter portion 185b. The small diameter portion 185a is provided at the end on the head portion 70a side. The small diameter portion 185a is formed by inserting and fixing a metal cylinder 186 into the end (upper end) of the large diameter portion 185b. That is, the arc extinguishing tube 185 includes a first cylindrical body (large diameter portion 185b) having a constant inner diameter from one end to the other end, and a first cylindrical body having a shorter axial length than the first cylindrical body and a smaller diameter than the first cylindrical body. It is formed by two cylindrical bodies (cylindrical body 186). Specifically, the columnar part 70b of the head fitting 70 is inserted through the upper end of the cylinder 186, and the washer 76 is press-fitted into the columnar part 70b. Further, the columnar part 70b of the head fitting 70 and the cylinder 186 are inserted through the upper end of the large diameter part 185b of the arc extinguishing tube 185, and the outer peripheral surface of the cylinder 186 and the inner peripheral surface on the upper end side of the large diameter part 185b are bonded. Fixed. In the fuse 112 as well, the columnar portion 70b is inserted into the cylindrical body 186 and the washer 76 is fixed to the columnar portion 70b, so the arc extinguishing tube 185 is rotatable with respect to the head fitting 70. Note that the outer circumferential surface of the columnar portion 70b and the inner circumferential surface of the cylindrical body 186 may be fixed by adhesive or the like.

(Third example)
The fuse 212 will be explained with reference to FIG. The fuse 212 is a modification of the fuses 12 and 112, and the shape of the arc extinguishing tube 285 is different from the shape of the arc extinguishing tubes 85 and 185 used in the fuses 12 and 112. Regarding the fuse 212, the same parts as the fuses 12, 112 are given the same reference numbers as those given to the fuses 12, 112, and the description thereof will be omitted.

The arc extinguishing tube 285 includes a small diameter portion 285a and a large diameter portion 285b. The small diameter portion 285a is provided at the end on the head portion 70a side. The small diameter portion 285a is formed by inserting and fixing a metal cylinder 186 into the end (upper end) of the large diameter portion 285b. In other words, the arc extinguishing tube 285 is composed of a first cylinder (large diameter portion 285b) and a second cylinder (cylindrical body 186) having a shorter axial length than the first cylinder and a smaller diameter than the first cylinder. It is formed. Further, a tapered inclined portion 285c is provided on the inner surface of the upper side (head portion 70a side) of the large diameter portion 285b so as to go around in the circumferential direction. The length of the inclined portion 285c is adjusted to be 1/2 to 2/3 of the length of the cylindrical body 186. Further, the inner diameter (maximum diameter) of the inclined portion 285c is 1.1 to 1.2 times the inner diameter of the large diameter portion 285b of the portion where the inclined portion 285c is not provided. It is formed so as to increase toward the portion 70a. As a result, a tapered inclined portion 285c is provided on the inner circumferential surface of the large diameter portion 285b in a part (head portion 70a side) where the outer circumferential surface of the cylinder 186 and the inner surface of the large diameter portion 285b face each other. ing.

In the arc extinguishing tube 285, the columnar part 70b of the head fitting 70 is inserted through the upper end of the cylinder 186, and the washer 76 is press-fitted and fixed to the columnar part 70b. Further, the columnar part 70b of the head fitting 70 and the cylinder 186 are inserted through the upper end of the large diameter part 285b of the arc extinguishing tube 285, and the outer peripheral surface of the cylinder 186 and the inner peripheral surface of the large diameter part 285b (the inner peripheral surface of the inclined part 285c) are inserted. (including the peripheral surface) are fixed with adhesive. Note that the inclined portion 285c prevents the adhesive from being scraped off when the lower end of the cylinder 186 is inserted through the upper end of the large diameter portion 285b, and contributes to strengthening the adhesive force between the cylinder 186 and the large diameter portion 285b. ing.

Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The techniques described in the claims include various modifications and changes to the specific examples illustrated above. Further, the technical elements described in this specification or the drawings exhibit technical usefulness singly or in various combinations, and are not limited to the combinations described in the claims as filed. Furthermore, the techniques illustrated in this specification or the drawings can achieve multiple objectives simultaneously, and achieving one of the objectives has technical utility in itself.

12: Fuse (fuse for high pressure blower)
46: Lower electrode 56: Upper electrode 70: Head metal fitting 70a: Head portion 70b: Columnar portion 76: Internal pressure adjustment member 80: Fusible connection wire 85: Arc extinguishing tube 85a: Small diameter portion 85b: Large diameter portion 92: Lower connection Line 100: High pressure fuser

Claims (6)

A high-pressure fuse disposed between the upper electrode and the lower electrode in a high-pressure fuse having an upper electrode connected to a power distribution line and a lower electrode connected to wiring on a high-voltage equipment side,
Fuses for high pressure blowers are
a head metal fitting connected to the upper electrode and having a head part and a columnar part;
a lower connection line connected to the lower electrode;
a fusible connection line connected between the head fitting and the bottom connection line;
A cylindrical arc-extinguishing tube surrounding the fusible connection wire,
The head part is located outside the arc extinguishing tube,
The columnar part extends from the head part into the arc extinguishing tube,
The arc extinguishing tube has a small diameter part that passes through the columnar part and is located at the head side end of the columnar part, and a large diameter part whose inner diameter is larger than the small diameter part,
a ring-shaped internal pressure adjusting member is fixed to the columnar part within the large diameter part with an inner peripheral part of the internal pressure adjusting member bent in a direction away from the head part;
A fuse for high-pressure fuses in which the arc-extinguishing tube is fixed to the head fitting by an internal pressure adjustment member. 2. The high-pressure fuse for a high-pressure fuse according to claim 1 , wherein a notch is provided on the inner circumferential surface of the small-diameter portion at a boundary between the small-diameter portion and the large-diameter portion of the arc extinguishing tube. The fuse for a high-pressure blower according to claim 1 or 2 , wherein the inner peripheral portion of the internal pressure adjusting member is fixed in a bent state away from the head portion. The fuse for a high-pressure blower according to any one of claims 1 to 3, wherein the internal pressure adjusting member is made of metal. The fuse for a high-pressure fuse according to claim 1 , wherein the small diameter portion is formed by fixing a cylindrical body separate from the large diameter portion to the inner circumferential surface of the large diameter portion. 6. The high-pressure fuse for a high-pressure fuse according to claim 5 , wherein an inclined portion is provided on the inner circumferential surface of the large diameter portion at a portion where the outer circumferential surface of the cylinder body and the inner circumferential surface of the large diameter portion face each other.

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