Terminal block

Abstract

Corona discharge may occur in the small gap between the tip of the screw and the bottom surface of the screw hole in the base body, potentially damaging the base body which is made of resin material. [Solution] The terminal block 1 comprises at least a base body 20 made of an insulating material, and a metal conductive support 30 attached to the end face 21 of the base body 20 to support and fix a pair of connection terminals 11A and 11B. The conductive support 30 comprises a plate portion 31 attached to the end face 21 along the end face 21 of the base body 20, a support column portion 32 erected from the plate portion 31 to support the connection terminals 11A and 11B, and a fastener 36 that fixes the connection terminals 11A and 11B to the support column portion 32 by screwing it into the support column portion 32 so as to sandwich the connection terminals 11A and 11B between itself and the plate portion 31.

Description

TECHNICAL FIELD

[0001] The present invention relates to a terminal block that electrically connects a pair of connection terminals. BACKGROUND ART

[0002] As this type of technology, for example, Patent Document 1 discloses a terminal block in which a pair of connection terminals are fixed to a block main body. The block main body is made of an insulating resin material, and screw holes are formed in the block main body. By screwing screws into the screw holes of the block main body, the connection terminals are sandwiched between the heads of the screws and the block main body, so that the connection terminals are fixed to the block main body. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0003] PATENT DOCUMENT 1 Japanese Patent No. 7607996 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] However, since there is generally a potential difference between the connection terminal and the block main body, the electric field tends to concentrate at the tip portion of the screw that is in contact with the connection terminal. As a result, if a slight gap exists between the tip portion of the screw and the bottom surface of the screw hole of the block main body, corona discharge may occur. This corona discharge may damage the block main body made of a resin material.

[0005] The present invention has been made in view of the above points, and an object of the present invention is to provide a terminal block capable of suppressing damage to the block main body for fixing connection terminals due to corona discharge. MEANS FOR SOLVING THE PROBLEMS

[0006] In view of the above problems, the terminal block according to the present invention is a terminal block for electrically connecting a pair of connection terminals, the terminal block comprising at least a base body made of an insulating resin material and a conductive support made of a metal material attached to the end face of the base body for supporting and fixing the pair of connection terminals. The conductive support comprises a plate portion attached to the end face of the base body along the end face, a support column portion erected from the plate portion and supporting the connection terminals, and a fastener that fixes the connection terminals to the support column portion by screwing it into the support column portion so as to sandwich the connection terminals between the plate portion and the fastener.

[0007] According to the present invention, the connection terminal can be supported on the support column portion erected from the plate portion, and the fixing device can be screwed onto the support column portion, thereby sandwiching the connection terminal between the plate portion and the fixing device. This allows the connection terminal to be fixed to the support column portion. Furthermore, since the plate portion is attached to the end face along the end face of the base body, and the support column portion of the conductive support is not erected directly from the base body, the occurrence of corona discharge between the conductive support and the base body can be suppressed, and damage to the resin base body due to corona discharge can be prevented.

[0008] In a more preferred embodiment, the plate portion has a through hole, and the support column portion has a fixing portion that is fixed to the plate portion by being press-fitted into the through hole, and a threaded portion that is continuous with the fixing portion and is screwed into the fastener.

[0009] In this embodiment, since the fixing portion of the support column is press-fitted into the plate portion, the support column can be stably erected on the plate portion. As a result, since no threaded portion is formed on the circumferential surface of the fixing portion of the support column, the phenomenon of excessive electric field concentration at the tip of the threaded portion can be avoided, and corona discharge from the fixing portion can be suppressed.

[0010] In a more preferred embodiment, the support column portion is continuous with the fixing portion and has a disc-shaped projection that protrudes from the surface of the plate portion that faces the end face of the base body, and a cylindrical recess is formed in the end face of the base body having a diameter larger than the diameter of the projection and a depth greater than the height of the projection, and the projection is housed in the recess in a state of non-contact with the wall surface of the recess.

[0011] In this embodiment, since the disc-shaped projection is housed in the recess without contacting the wall surface of the recess, the electric field from the connection terminal can be dispersed around the periphery of the end face of the projection. This prevents corona discharge between the conductive support and the base body.

[0012] In a more preferred embodiment, the plate portion has an insertion hole for inserting a resin screw, the end face of the base body has a screw hole for screwing the screw into, and the plate portion is fixed to the base body by screwing the screw into the screw hole with the screw inserted through it.

[0013] In this embodiment, the plate portion is fixed to the base body by inserting a screw made of resin material through it and screwing the screw into the screw hole, so that the electric field does not concentrate at the tip of the resin screw. This prevents corona discharge between the conductive support and the base body.

[0014] In a more preferred embodiment, the plate portion is made of copper or a copper alloy, and the support column portion is made of stainless steel.

[0015] According to this aspect, by forming the plate portion from copper or a copper alloy, the electrical conductivity between the connection terminals can be enhanced, and resistive heating of the plate portion can be suppressed. Furthermore, since the support pillar portion is made of stainless steel, the strength of the support pillar portion can be increased compared to a case where it is made of copper or a copper alloy. As a result, even if a fastener is screwed into the support pillar portion and over-tightened, plastic deformation and crushing of the threads of the support pillar portion can be avoided. Effects of the Invention

[0016] According to the present invention, damage to the base body that fixes the connection terminals due to corona discharge can be suppressed. Brief Description of the Drawings

[0017] [Figure 1] It is a schematic perspective view of the terminal block according to the present embodiment of the present invention. [Figure 2] It is an exploded perspective view of the terminal block shown in Figure 1. [Figure 3] (a) is a schematic perspective view of the conductive support, (b) is a schematic perspective view of (a) viewed from the back surface, and (c) is an exploded perspective view of the conductive support of (a). [Figure 4] (a) is a cross-sectional view of the terminal block viewed from the direction of the arrows along line A-A shown in Figure 1, and (b) is a cross-sectional view of the terminal block viewed from the direction of the arrows along line B-B shown in Figure 1. [Figure 5] It is an enlarged cross-sectional view of the main part of Figure 4(a). [Figure 6] It is an exploded perspective view of the terminal block according to a modified example. Modes for Carrying Out the Invention

[0018] Hereinafter, the terminal blocks 1 and 1A according to the present embodiment and its modified example will be described with reference to Figures 1 to 6.

[0019] As shown in Figure 1, the terminal block 1 is for electrically connecting a pair of connection terminals 11A and 11B. The connection terminal 11A (11B) is attached to the tip of a high-voltage cable 7A (7B) of more than ten kV. By bringing the connection terminals 11A and 11B into contact using the terminal block 1, or by making the connection terminals 11A and 11B indirectly conductive via the terminal block 1, the high-voltage cables 7A and 7B can be electrically connected to each other.

[0020] In the present embodiment, the connection terminal 11A (11B) is a round crimp terminal made of a metal material such as aluminum. The connection terminal 11A (11B) may be, for example, an open-end crimp terminal or a CB-type crimp terminal, and its shape is not particularly limited as long as the connection terminals 11A and 11B can be directly or indirectly connected using the terminal block 1.

[0021] The connection terminal 11A (11B) includes a wire fixing portion 12A (12B) fixed to the tip of the high-voltage cable 7A (7B), and a terminal connection portion 13A (13B) that electrically connects the connection terminal 11A (11B) to the counterpart connection terminal 11B (11A).

[0022] In the present embodiment, the wire fixing portion 12A (12B) has a block shape, but may have a cylindrical shape. In the present embodiment, the block-shaped wire fixing portion 12A (12B) is formed with an insertion hole into which the electric wire 71 of the high-voltage cable 7A (7B) is inserted. As shown in Figure 4(b), the wire fixing portion 12A (12B) fixes the electric wire 71 by crimping or the like in a state where the electric wire 71 exposed from the insulating coating 72 is accommodated at the tip portion of the high-voltage cable 7A (7B). The terminal connection portion 13A (13B) is formed continuously from the wire fixing portion 12A (12B).

[0023] The terminal connection portion 13A (13B) has an insertion portion 14A (14B) through which the support column portion 32, described later, is inserted. In this embodiment, since the connection terminal 11A (11B) is a round crimp terminal, the outer shape of the terminal connection portion 13A (13B) is roughly ring-shaped, and a circular insertion portion 14A (14B) is formed in the center. For example, if the connection terminal 11A (11B) is an open-ended crimp terminal, a U-shaped insertion portion is formed.

[0024] The terminal block 1 comprises a base body 20 and a conductive support 30. The base body 20 is erected, for example, inside a grounded enclosure (not shown). Inside the enclosure are devices (not shown) or circuit boards (not shown) connected to the high-voltage cables 7A and 7B, respectively. The base body 20 is columnar, and in this embodiment, the base body 20 is cylindrical.

[0025] The base body 20 is fixed to the housing with one end face 25 of the base body 20 in contact with the housing. A side surface 22 is formed between the one end face 25 and the other end face 21 of the base body 20. Since the side surface 22 is a circumferential surface without corners, corona discharge is unlikely to occur between the side surface 22 and high-voltage components (not shown) inside the housing.

[0026] As shown in Figure 2, the other end face 21 of the base body 20 is circular in shape. A cylindrical recess 24 is formed in the center of the end face 21 of the base body 20. Furthermore, a pair of screw holes 23, 23 for attaching the conductive support 30 are formed on the end face 21 of the base body 20, flanking the recess 24. The inner circumferential surface of the screw holes 23 has a female thread that screws onto the shaft portion 44 (male thread) of the screw 40.

[0027] The base body 20 is made of an insulating resin material. The resin material of the base body 20 is not particularly limited as long as it has insulating properties, but it is preferable that it has insulating properties, heat resistance, and voltage resistance.

[0028] In this embodiment, the conductive support 30 is attached to the end face 21 of the base body 20. The conductive support 30 supports and fixes a pair of connection terminals 11A and 11B. The conductive support 30 is made of a metal material. As shown in Figures 2 and 3(a) to (c), the conductive support 30 comprises a plate portion 31 attached to the end face 21 of the base body 20, and a support column portion 32 that rises from the plate portion 31 and supports the connection terminals 11A and 11B.

[0029] The plate portion 31 is disc-shaped, and a cylindrical through-hole 38 is formed in the center of the plate portion 31. On the surface 31a of the plate portion 31 on the side where the support column portion 32 is erected, a tapered surface 37 is formed along the opening edge of the through-hole 38.

[0030] The plate portion 31 has a pair of through holes 39, 39 through which screws 40 made of resin material are inserted. The pair of through holes 39, 39 are formed on either side of the through hole 38. When the plate portion 31 is placed on the end face of the base body 20, each of the through holes 39 is formed in a position continuous with the screw holes 23 on the end face 21 of the base body 20.

[0031] The screw 40 is made of an insulating resin material, and the resin material is not particularly limited as long as it is insulating; for example, a fluororesin can be used. The screw 40 has a head 43 into which the tip of a tool such as a screwdriver engages, and a shaft portion 44 extending from the head 43. A male thread is formed on the shaft portion 44. The plate portion 31 is fixed to the base body 20 by inserting the screws 40 through each insertion hole 39, screwing the shaft portion 44 of the screw 40 into the screw hole 23 of the base body 20, and tightening the screws 40.

[0032] As shown in Figure 3(c), the support column 32 is a cylindrical shaft that is fixed to the plate 31 by being press-fitted into the through hole 38. The support column 32 has a fixing portion 33 fixed to the plate 31 and a threaded portion 34 that is continuous with the fixing portion 33 and is screwed into the fastener 36. The threaded portion 34 is erected from the plate 31 on the surface 31a side of the plate 31, and male threads are formed on the circumferential surface of the threaded portion 34 for screwing into the fastener 36.

[0033] Furthermore, the area within the threaded portion 34 where the male thread is formed only needs to be within the range where the pair of connection terminals 11A and 11B can be crimped by tightening the fastener 36. Therefore, with the pair of connection terminals 11A and 11B attached, the area from the opposing surfaces of the insertion portions 14A and 14B of the pair of connection terminals 11A and 11B to the opposing surface of the tapered surface 37, which will be described later, may be a cylindrical surface without male threads.

[0034] The fixing portion 33 of the support column 32 is a cylindrical portion and is press-fitted into the through hole 38 of the plate portion 31. This allows the support column 32 to be stably erected on the plate portion 31. In this embodiment, since the support column 32 is fixed by press-fitting, no threaded portion is formed on the circumferential surface of the fixing portion 33 of the support column 32. Therefore, excessive concentration of the electric field on the surface of the fixing portion 33 can be avoided, and corona discharge from the fixing portion 33 can be suppressed.

[0035] The plate portion 31 and the support column portion 32 are made of a metal material and are not particularly limited as long as they are conductive, however, it is preferable that the plate portion 31 be made of copper or a copper alloy and the support column portion 32 be made of stainless steel.

[0036] By making the plate portion 31 out of copper or a copper alloy, the electrical conductivity between the connection terminals 11A and 11B can be improved, and the resistive heat generation of the plate portion 31 can be suppressed. Furthermore, by making the support column portion 32 out of stainless steel, the strength of the support column portion 32 can be increased compared to when it is made out of copper or a copper alloy. As a result, even if the fastener 36 is screwed into the support column portion 32 and overtightened, it is possible to avoid the screw threads of the threaded portion 34 of the support column portion 32 from plastically deforming and being crushed.

[0037] As shown in Figures 4(a) and (b), the support column portion 32 has a protruding portion 35 that is continuous with the fixing portion 33. The protruding portion 35 is a disc-shaped projection from the surface (back surface) 31b of the plate portion 31 that faces the end face 21 of the base body 20. With the conductive support 30 attached to the end face 21 of the base body 20 by a pair of screws 40, 40, the protruding portion 35 is housed in a cylindrical recess 24 formed in the end face 21 of the base body 20.

[0038] In this embodiment, with the conductive support 30 attached to the base body 20, the axis of the support column 32 coincides with the axis of the cylinder that forms the shape of the recess 24. As shown in Figure 5, the recess 24 has a diameter D2 that is larger than the diameter D1 of the projection 35, and a depth H2 that is larger than the height H1 of the projection 35. As a result, the projection 35 is housed in the recess 24 without contacting the wall surfaces 24a and 24b of the recess 24.

[0039] Furthermore, it is structurally difficult to make the surface (back surface) 31b of the plate portion 31 and the end surface 35a of the protruding portion 35 flush. Therefore, normally, the end surface 35a of the support column portion 32 will either protrude or be recessed compared to the surface (back surface) 31b of the plate portion 31.

[0040] As described above, the fixing portion 33 of the support column portion 32 is press-fitted into the through hole 38 of the plate portion 31. Therefore, in order to ensure mechanical strength, it is preferable that the end face 35a of the support column portion 32 protrudes more than the surface (back surface) 31b of the plate portion 31.

[0041] If the end face 35a of the support column 32 protrudes beyond the surface (back surface) 31b of the plate 31, the protruding portion is formed as a protrusion 35, and therefore a recess 24 needs to be provided. Here, if the end face 35a of the support column 32 protrudes beyond the surface (back surface) 31b of the plate 31, the electric field will concentrate at the corner of the protrusion 35. In this state, if the distance between the corner of the protrusion 35 and the base body 20 and the wall surfaces 24a and 24b of the recess 24 is short, corona discharge will occur. Therefore, in order to prevent corona discharge, it is preferable to increase the distance between the corner of the protrusion 35 of the support column 32 and the wall surfaces 24a and 24b of the base body 20 and the recess 24. The appropriate value of this distance will vary depending on the magnitude of the applied voltage, etc., so it is best to conduct experiments and design it according to the actual situation.

[0042] The conductive support 30 further comprises a fastener 36. The fastener 36 is a nut made of a metal material such as stainless steel or aluminum. As shown in Figures 4(a) and (b), the fastener 36 is screwed onto the support column 32, thereby fixing the connection terminals 11A and 11B to the support column 32, sandwiching them between the plate portion 31 and the fastener 36.

[0043] According to this embodiment, as shown in Figures 2 and 4(a), with a pair of screws 40, 40 inserted through the insertion holes 39, 39 of the plate portion 31, the shaft portion 44 of each screw 40 is screwed into the screw hole 23 of the base body 20 and tightened. This sandwiches the plate portion 31 between the head 43 of each screw 40 and the base body 20, fixing the plate portion 31 to the base body 20 and allowing the conductive support 30 to be attached to the base body 20.

[0044] In this embodiment, since the base body 20 and the screw 40 are made of resin material, the electric field does not concentrate at the tip of the male thread on the shaft portion 44 of the screw 40. This prevents corona discharge between the conductive support 30 and the base body 20 in the internal space of the screw hole 23.

[0045] In this mounting state, the insertion parts 14A and 14B of the connection terminals 11A and 11B are inserted in order into the support column 32 that is erected from the plate portion 31, thereby supporting the connection terminals 11A and 11B on the support column 32. In this supported state, the fastener 36 is screwed onto the support column 32 and the fastener 36 is tightened. As a result, the overlapping terminal connection parts 13A and 13B are sandwiched between the plate portion 31 and the fastener 36.

[0046] Therefore, the pair of connection terminals 11A and 11B (terminal connection parts 13A and 13B) can be crimped together and fixed to the support column 32. As a result, the high-voltage cables 7A and 7B are electrically connected to each other via the pair of connection terminals 11A and 11B.

[0047] In this embodiment, the support column portion 32 inserted into the insertion portions 14A and 14B of the terminal connection portions 13A and 13B is also made of metal, and the fixing device 36 and plate portion 31 that clamp the terminal connection portions 13A and 13B are also made of metal. As a result, the electrical conductivity between the connection terminals 11A and 11B is improved, and the electrical connection of the high-voltage cables 7A and 7B can be stably ensured.

[0048] Furthermore, as shown in Figures 4(b) and 5, the plate portion 31 is attached to the end face 21 of the base body 20 along the end face 21, eliminating the need to screw a threaded shaft or the like, corresponding to the support column portion 32, into the base body 20 and erect it directly from the base body 20. This suppresses the occurrence of corona discharge between the conductive support 30 and the base body 20, preventing damage to the base body 20, which is made of resin material, due to corona discharge.

[0049] Furthermore, in this embodiment, a tapered surface 37 is formed on the surface 31a of the plate portion 31 along the opening edge of the through hole 38. The reason for this is explained below. If the tapered surface 37 is not formed, as shown in Figure 3(c), when the support column portion 32 is press-fitted, the portion where the plate portion 31 and the support column portion 32 come into contact will bulge, and the surface 31a of the plate portion 31 will not make flush contact with the connection terminal 11B, potentially creating a minute gap between the connection terminal 11B and the plate portion 31. Because there is an air layer in the minute gap, an electric potential is generated, and it appears to have electrical resistance. Therefore, it may generate heat when current flows. In contrast, by forming the tapered surface 37 as in this embodiment, even when the support column portion 32 is press-fitted, deformation of the plate portion 31 prevents the surface 31a of the connection terminal 11B from making flush contact with the connection terminal 11B, thus preventing the formation of a minute gap between the connection terminal 11B and the plate portion 31. Therefore, it does not generate heat as it does when the tapered surface 37 is not formed.

[0050] Figure 6 is an exploded perspective view of a modified terminal block 1A. In the embodiments shown in Figures 1 to 5, one support column 32 is provided on the conductive support 30A, but for example, as shown in the modified example in Figure 6, a support column 32A (32B) may be provided on the conductive support 30A for each connection terminal 11A (11B). Each support column 32A (32B) is press-fitted into a through hole formed in the conductive support 30A and is provided with a threaded portion 34A (34B) that is screwed onto the fasteners 36A and 36B. In this modified example as well, tapered surfaces 37A and 37B are formed along the opening edge of the through hole, similar to the embodiment described above.

[0051] Similarly, each support column 32A (32B) has a protrusion (not shown) that extends from the surface (back surface) 31b of the plate portion 31, and each protrusion is housed in a recess 24A (24B) formed on the end face 21 of the base body 20. According to this modification, the connection terminals 11A and 11B can be electrically connected via the plate portion 31 of the conductive support 30A without overlapping them.

[0052] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various design modifications can be made without departing from the spirit of the invention as described in the claims.

[0053] In this embodiment and its modified form, the conductive supports 30 and 30A are fixed to the base body 20 by screws 40, thereby stably restraining the conductive supports 30 and 30A to the base body 20 regardless of the difference in thermal expansion between the conductive supports 30 and 30A and the base body 20. However, if the heat generated by these components is small, the conductive supports 30 and 30A may be attached to the base body 20 via an adhesive or the like.

[0054] Furthermore, although the base body 20 is cylindrical in this embodiment and its modified form, it is not limited to this. For example, steps with alternating small and large diameters may be provided on the cylindrical surface to increase the creepage distance between one end face 25 and the other end face 21 of the base body 20, thereby making it less likely for corona discharge to occur between the conductive support 30 and the housing. [Explanation of symbols]

[0055] 1, 1A: Terminal block, 11A, 11B: Connection terminal, 20: Base body, 21: End face, 23: Screw hole, 24: Recess, 24a, 24b: Wall surface, 30, 30A: Conductive support, 31: Plate part, 31: Plate part, 32, 32A, 32B: Support column part, 33: Fixing part, 34: Screw part, 35: Protrusion, 35a: End face, 35b: Periphery, 36, 36A, 36B: Fixing device, 37: Tapered surface, 38: Through hole, 39: Insertion hole, 40: Screw

Claims

1. A terminal block for electrically connecting a pair of connection terminals, The aforementioned terminal block is A base body made of an insulating resin material, A conductive support made of a metal material is attached to the end face of the base body and supports and fixes a pair of the connection terminals, It has at least the following features: The conductive support is Along the end face of the base body, a plate portion attached to the end face, A support column portion is erected from the plate portion and supports the connection terminal, A fixing device that secures the connection terminal to the support column by screwing it into the support column so as to sandwich the connection terminal between itself and the plate portion, A terminal block characterized by having the following features.

2. The plate portion has through holes formed in it. The support column portion is fixed to the plate portion by being press-fitted into the through hole, The terminal block according to claim 1, characterized in that it has a screw portion that is continuous with the fixing portion and is screwed into the fixing device.

3. The support column portion is continuous with the fixing portion and has a disc-shaped projection that protrudes from the surface of the plate portion that faces the end face of the base body. A cylindrical recess is formed on the end face of the base body, having a diameter larger than the diameter of the protrusion and a depth larger than the height of the protrusion. The terminal block according to claim 2, characterized in that the protruding portion is housed in the recess in a state of non-contact with the wall surface of the recess.

4. The plate portion has an insertion hole formed therein for inserting a screw made of resin material. The end face of the base body has a screw hole formed therein, into which the screw is screwed. The terminal block according to claim 1, characterized in that the plate portion is fixed to the base body by inserting the screw through it and then screwing the screw into the screw hole.

5. The aforementioned plate portion is made of copper or a copper alloy. The terminal block according to claim 2, characterized in that the support column portion is made of stainless steel.

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