JPH0442808B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a bushing that is attached to an electrical device such as a transformer, and a terminal fitting that is attached to the head of the bushing, and an outlet led out from a coil of the electrical device. The present invention relates to an improved method for connecting lead wires to wires directly or via a tap board.

[Prior art]

Conventionally, for example, when connecting the lead wire led out from the primary side of the transformer coil and the terminal fitting fixed to the head of the bushing directly by the lead wire or via a tap board, the method shown in Fig. 1 was used. This is done as shown in . That is, in FIG. 1, a lead wire 1 made of a stranded wire, for example, a large number of small-diameter copper wires converged, is connected to an outlet wire led out from a coil (not shown), and a threaded portion 2a is attached to the top of the lead wire 1. It has a screw shaft 2 screwed into it, has an enlarged flange 3 in the central part from which the screw shaft 2 is protruded, and further has this enlarged flange 3.
A cylindrical connecting terminal 5 with a mounting hole bored on the lower side is inserted into the connecting terminal portion 5 of the integrally formed connecting fitting 4, and the outer periphery of the connecting terminal portion 5 is crushed with a crimping tool. The lead wire 1 and the connecting fitting 4 are crimped and connected, and then a packing or washer is fitted onto the screw shaft 2 of the connecting fitting 4 and placed on the enlarged flange 3. In this state, the connecting fitting 4 is connected. The screw shaft 2 is inserted into the center hole 7 from the bottom side of the bushing 6 and protrudes from the small diameter through hole 8 at the top of the bushing 6, and the screw shaft 2 protruding from the head of the bushing 6 is connected to the screw shaft 2 through the packing 10 to form a clamp-shaped screw shaft. The lead wire 1 was connected to the bushing 6 by screwing and attaching a terminal fitting 9 for connecting an external conductor to the upper end surface of the head of the bushing 6. However, in the lead wire connection method described above,
Screw the terminal fitting 9 onto the connecting fitting 4 and attach the bushing 6.
, screw the terminal fitting 9 onto the screw shaft 2 of the connecting fitting 4 protruding from the upper end surface of the bushing 6 until it can be tightened by hand, and then insert the fastening tool 11 such as a box into the center hole of the bushing 6. 7 and fitted into the enlarged flange 3 (nut) of the connecting fitting 4, and in this state, the connecting fitting 4 was rotated to screw the terminal fitting 9. In this case, the tightening fitting 11 As shown in FIG. 4, the nut-shaped enlarged flange 3 into which the
Since it is provided on the outside of the connection terminal portion 5 into which the lead wire 1 is inserted and connected, the center hole 7 of the bushing 6
The diameter of the bushing 6 becomes large, and the bushing 6 itself becomes large.

When connecting the lead wire 1 by inserting it into the connecting terminal portion 5, insert the core wire portion 1a of the lead wire 1, which is formed by rope-shaped plurality of small diameter copper wires, into the mounting hole of the connecting terminal portion 5. , as shown in FIG. 2, the connection was made by crushing the connection terminal portion 5, but in this method,
When crushing the connecting terminal part 5, for example, if the lower side of the connecting terminal part 5 is supported with a semicircular jig and the upper side is crushed with a protruding jig, the most force is applied to the connecting terminal part 5. That is, a part of the core wire portion 1a located in the direction of arrow P in FIG. 3 may be stretched and cut.
Furthermore, when the connecting terminal portion 5 is crushed from the upper direction, the end portion perpendicular to the crushing direction (the portion seen by the Y arrow in FIG. 2) escapes in the lateral direction and cannot be sufficiently crimped, forming the core wire portion 1a. It is easy to create gaps between the copper wires.
Moreover, if the crushing direction of the connecting terminal part 5 is not considered, the end Y perpendicular to the crushing direction of the connecting terminal part 5,
If Y exceeds the outer diameter dimension a of the nut part of the enlarged collar part 3 shown in FIG. The crushing work required great skill and was inefficient. Furthermore, in the above connection method, a part of the core wire portion 1a of the lead wire 1 may be cut or the crimping may be insufficient. It is difficult for each core wire portion 1a of the wire 1 to be brought into contact with each other at a uniform cross-sectional area, and as a result, the flow of current at the connection portion becomes uneven and there is a risk of local overheating.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks, quickly and reliably connects a lead wire to a connecting fitting for tightening and fixing a terminal fitting for connecting an external conductor to the head of a bushing, and also To provide a lead wire connection method for a bushing, which enables the bushing to be made smaller and lighter by smoothly tightening and fixing the connecting fitting and the terminal fitting using a connecting part without increasing the size of the bushing.

[Summary of the invention]

This invention involves inserting a core wire of a lead wire into a connecting terminal portion of a connecting fitting, and then compression molding the connecting terminal portion into a rectangular shape such as a hexagon to connect the lead wire and the connecting fitting. The fastener is fitted using the corner part of the connected terminal part, and the connecting fitting and the terminal fitting for connecting the external conductor can be tightened and fixed without increasing the size of the bushing. It is characterized by

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 5 to 12.

In FIG. 5, 21 is a bushing, which has a large diameter center hole 22 at the center of the interior, and a bushing 2 that is smaller in diameter than this center hole 22 and communicates with the center hole 22.
A through hole 23 is formed through the upper end surface of the head of the head. 24 is a connection fitting for connecting lead wires, and as shown in Figs. 5 and 9, there is a screw part 2 on the top.
5a is screwed to the tip, and an annular collar portion 25b having a slightly larger diameter than the screw shaft 25 is provided in the center,
Furthermore, the annular flange 25 is provided on the lower side of the annular flange 25b.
The diameter is slightly smaller than b and the lead wire 2 is installed inside.
It is integrally molded from a highly conductive material such as copper, with a connecting terminal portion 25c having a mounting hole 25d into which the core wire portion 26a of No. 6 can be inserted. When the lead wire 26 is inserted and connected to the connection fitting 24, the lead wire 26 is inserted into the mounting hole 25d provided in the connection terminal portion 25c of the connection fitting 24 shown in FIG.
10, between a pair of dies 27, 27a for compression-molding the connecting terminal portion 25c into a hexagonal longitudinal section, for example.
Insert as shown in FIG. Then, the upper die 27 is lowered toward the lower die 27a by the hydraulic drive source 28. Then, the connection terminal portion 25c of the connection fitting 24 is compression-molded from the circular state shown in FIG. 10 to a hexagonal longitudinal section as shown in FIG. 12. At this time, the connecting terminal portion 25c is pressed with a uniform force toward the center of the core wire portion 26a of the lead wire 26 by the side between each vertex of each die mold 27, 27a. The core wire portion 26a of the wire 26 is also pressed in the same direction. When the core wire portion 26a is pressed toward its center by the compression of the connecting terminal portion 25c, the core wire portion 26a resists the pressing force.
A reaction force is generated at the center of the core wire portion 26a (a force acting outward from the center of the core wire portion 26a), and the core wire portion 26a has a balance between the pressing force generated during compression molding of the connection terminal portion 25c and the reaction force opposing it. The core wire portion 26a of the lead wire 26 is pressed with a uniform force. Therefore, by compressing and molding the connection terminal portion 25c into a rectangular shape, there is no possibility that a part of the core wire portion 26a of the lead wire 26 will be stretched or crushed.
The individual copper wires constituting the core wire portion 26a of the lead wire 26 are pressed and held with a substantially uniform contact area, so that the connection terminal portion 25c of the connection fitting 24 can be connected smoothly and well.

As described above, connect the connecting fitting 24 and the lead wire 2.
6, insert the connecting fitting 24 into the center hole 22 from the bottom of the bushing 21 with the screw shaft 25 facing upward, and tighten the threaded portion 25a at the tip of the screw shaft 25.
A terminal fitting 30 is made to protrude from the through hole 23 in the upper part of the bushing 21 through the packing 29 and the flat washer 29a, and in this state tightens and fixes an external conductor (not shown) from the head of the bushing 21, and is screwed onto the bottom surface of the terminal fitting 30. The threaded portion 25 of the screw shaft 25 is inserted into the hole 30a.
Install a by screwing it together. When the terminal fitting 30 is screwed onto the screw shaft 25a of the connecting fitting 24, a fastener 31 is used to make the screwing firm. In this case, the connection terminal portion 25c of the connection fitting 24 is compression molded into a rectangular shape for connection with the lead wire 26, so the fastener 31 is connected to the lead wire 26 at the center thereof. 26 inserted into the center hole 22 from the bottom of the bushing 21,
Engage with the connection terminal portion 25c formed in a square shape on the lower side of the annular collar portion 25b as shown in FIGS. 6 and 8,
When the connecting fitting 24 is rotated by the fastener 31, the connecting fitting 24 is firmly tightened and fixed to the terminal fitting 30 with the annular collar portion 25b being received by the upper end inside the bushing 21 via the packing 29 etc. This completes the attachment of the terminal fitting 30 to the bushing 21.

〔Effect of the invention〕

As explained above, in this invention, the lead wire and the connecting fitting are connected by compression molding the connecting terminal part of the connecting fitting into a rectangular shape, and the top of the bushing is attached to the connecting fitting to which the lead wire is connected. The screwing with the terminal fitting to be fastened is performed by making use of the rectangular part molded on the connecting terminal part of the connecting fitting and using a fastener to firmly screw the connecting fitting to the terminal fitting. Therefore, the above-described connection method has the following effects.

(1) When connecting lead wires, the connection terminal part of the connecting fitting is compressed into a square shape without protruding outward from its outer circumference, so that it can be smoothly connected without stretching or crushing the core part of the lead wire. When the lead wire is connected, the core wire is bonded and fixed to the connecting fitting by contacting the multiple copper wires that make up the lead wire with a nearly uniform cross-sectional area. There is no possibility that the connection will locally overheat due to improper connection.

(2) In addition, the connection terminal part of the connection fitting can be connected to the lead wire without exceeding the outer circumference of the connection terminal part and without pressing the core part of the lead wire. When tightening and fixing the connecting fitting and the terminal fitting, the fastener can be easily engaged using the square portion of the connecting terminal portion.

(3) Furthermore, the connection terminal portion of the connection fitting that the fastener engages is provided with a diameter smaller than the diameter of the annular flange that prevents the connection fitting from coming off the bushing. Compared to the case where the fastener is engaged with a nut provided on the enlarged flange, the diameter of the bushing can be made smaller. It can be made smaller.

As described above, by adopting the lead wire connection method of the present invention, the connection work between the lead wire and the connecting fitting can be performed quickly and reliably without disturbing the connection part of the lead wire, and without requiring any special skill. In addition, the connecting terminal part of the connecting fitting is compressed into a rectangular shape when connected to the lead wire, and this part can be used as the engaging part with the fastener, so the diameter of the bushing can be reduced. The bushing can be made smaller. Furthermore, by making the bushing smaller, it becomes possible to reduce the size and weight of electrical equipment such as transformers that use the bushing, and it has many excellent effects such as being able to manufacture electrical equipment economically.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view of a bushing showing a conventional lead wire connection method, Figure 2 is a cross-sectional view taken along line A-A in Figure 1, and Figure 3 shows the state before connecting the connecting fitting to the lead wire. The cross-sectional view shown in FIG. 4 is a front view of the connecting fitting. FIG. 5 is a longitudinal cross-sectional view of a bushing with lead wires connected by the lead wire connecting method of the present invention, FIG. 6 is a cross-sectional view taken along line B-B in FIG. 8 is a front view of the connecting fitting used in the present invention, FIG. 9 is a perspective view, and FIGS. 10 to 12 are for sequentially explaining the compression molding process of the connecting terminal part of the connecting fitting. FIG. 21...Butting, 24...Connection fittings, 25
... Screw shaft, 25b ... Annular collar portion, 26 ... Lead wire, 26a ... Core wire portion, 27, 27a ... Dice type, 31 ... Fastener.

Claims (1)

[Claims] 1. A connecting fitting with a screw shaft at the top, an annular flange with a diameter larger than the screw shaft in the center, and a cylindrical connection terminal at the bottom of the annular flange is made of a highly conductive material such as copper. The core wire of the lead wire was inserted into the connection terminal part of the connection fitting, and the connection terminal part was compression molded into a square shape to connect the connection fitting and the lead wire, and the lead wire was connected. The connecting fitting is inserted into the center hole of the bushing so that the tip of the screw shaft protrudes from the upper end surface of the bushing, and the terminal fitting is screwed onto the screw shaft, and the connecting terminal portion of the connecting fitting is formed into a rectangular shape. A bushing lead wire connection method comprising engaging a fastener, rotating the connecting metal fitting with the fastener, and fastening the terminal metal fitting to the upper end of the bushing via a screw shaft.