WO2011064639A1

WO2011064639A1 - Screw terminal and receptacle including same

Info

Publication number: WO2011064639A1
Application number: PCT/IB2010/002945
Authority: WO
Inventors: Kazuhiro Kato; Satoru Ueno; Maki Kondou; Toshiyuki Takii; Takashi Kawamoto
Original assignee: Panasonic Electric Works Co Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 2009-11-24
Filing date: 2010-11-17
Publication date: 2011-06-03
Anticipated expiration: 2012-05-24
Also published as: WO2011064639A9; TW201131914A; JP2011113680A; CN102668246A

Abstract

A screw terminal includes an electrical wire connecting portion to which an electrical wire is connected by a screw member, and a plug-pin receiver for gripping a plug pin of a plug. The electrical wire connecting portion and the plug-pin receiver are made from a single metal plate. The plug-pin receiver has a tubular shape extending along an insertion direction of the plug pin and the electrical wire connecting portion is formed as a frame body opened along the plug-pin insertion direction. A connecting portion connects the plug-pin receiver to the frame body. The plug- pin receiver has a substantially cylindrical shape, and the electrical wire is firmly pressed against an inner peripheral surface of the frame body by tightening the screw member into the frame body.

Description

SCREW TERMINAL AND RECEPTACLE INCLUDING SAME

Field of the Invention The present invention relates to a screw terminal for supplying electric power from an electrical wire to a plug in a state where round plug pins of the plug and the electrical wire are connected to the screw terminal, and a receptacle including the same.

Background of the Invention

As for a screw terminal, there has been known one including a plug-pin receiving member for receiving plug pins of a plug and a frame-shaped pillar member (electrical wire connection unit) into which an electrical wire is inserted. In such screw terminal, a screw member screwed into the pillar member is firmly tightened, and the electrical wire is firmly pressed against one end of the pillar member (see, e.g., Japanese Patent Application Publication No. 2000-243473) .

Specifically, as shown in Fig. 13A, a tapped hole 212 into which a screw member 220 is screwed is provided at a surrounding wall 211 of a pillar member 210. A holding part 231 of a plug-pin receiving member 230 is inserted into the surrounding wall 211 to face the tapped hole 212 in an up- down direction Z.

By firmly tightening the screw member 220 in a state where an electrical wire WR is inserted in the surrounding wall 211 to pass therethrough in a front-rear direction X, the electrical wire WR is held between an end portion 221 of the screw member 220 and the holding part 231.

However, the screw terminal 200 including the pillar member 210 and the plug-pin receiving member 230 is disadvantageous in that the pillar member 210 and the plug- pin receiving member 230 separately provided increase the number of components and also increases the number of assembly operations. To that end, it is considered to form the pillar member 210 and the plug-pin receiving member 230 as one unit. For example, as shown in Fig. 13B, when the pillar member 210 and the plug-pin receiving member 230 are formed as one unit, the screw terminal 200 has a complicated shape, Accordingly, a complicated bending process is required, which makes it difficult to manufacture the screw terminal 200. As a result, the costs for the screw terminal and the receptacle including the same are increased.

Summary of the Invention In view of the above, the present invention provides a screw terminal having a plug-pin receiving member (plug-pin receiver) and an electrical wire connection unit formed as one unit with ease and a receptacle including the same.

In accordance with an aspect of the present invention, there is provided a screw terminal including: an electrical wire connecting portion to which an electrical wire is connected by a screw member; and a plug-pin receiver for gripping a plug pin of a plug. The electrical wire connecting portion and the plug-pin receiver are made from a single metal plate. The plug-pin receiver has a tubular shape extending along an insertion direction of the plug pin, and the electrical wire connecting portion is formed as a frame body opened along the plug-pin insertion direction.

The screw terminal further includes a connecting portion for connecting the plug-pin receiver and the frame body, wherein the plug-pin receiver has a substantially cylindrical shape, and the electrical wire is firmly pressed against an inner peripheral surface of the frame body by tightening the screw member into the frame body.

With such configuration, the plug-pin receiver and the electrical wire connecting portion are made from a single metal plate and thus can be formed as one unit. Further, since the plug-pin receiver and the electrical wire connecting portion are formed simply by bending, even if the plug-pin receiver and the electrical wire connecting portion are formed as one unit, the manufacturing process thereof can be simplified.

The frame body may have a tapped hole into which the screw terminal is screwed, and the tapped hole is formed by burring.

With such configuration, the tapped hole is formed by burring, so that the number of components of the screw terminal can be reduced compared to a case where the tapped hole is formed separately from the frame body. In addition, the area of the inner surface of the tapped hole into which the screw member is screwed can be increased compared to a case where the tapped hole is formed in the frame body within a thickness thereof .

The frame body may have a portion where side end portions of the metal plate are overlapped, and a tapped hole into which the screw member is screwed is formed at the portion.

With such configuration, the tapped hole is formed at the portion of the frame body where the side end portions of the metal plate are overlapped. Therefore, even if the burring for forming the tapped hole is omitted, it is possible to ensure the area of the inner surface of the tapped hole into which the screw member is screwed.

The plug-pin receiver may have a plug-pin holding part which determine a minimum diameter of an inner diameter of the plug-pin receiver and a tip end part which extend from the plug-pin holding part along the plug-pin insertion direction, the tip end part having a gradually increased inner diameter.

With such configuration, the plug-pin receiver has the tip end part, so that it is possible to suppress arc generated between the plug pin and the plug-pin receiver from affecting other components of the receptacle compared to a case of the plug-pin receiver without the tip end part.

The tip end part of the plug-pin receiver may have a higher melting point than that of portions other than the tip end part.

The tip end part of the plug-pin receivers receives the arc, so that the tip end part is easily melted by the arc compared to the other parts. In the present invention, the tip end part of the plug-pin receiver has a higher melting point compared to the other parts and thus can be prevented from being melted by the arc.

The plug-pin receiver may have a plurality of gripping pieces formed by slits extending along the plug-pin insertion direction.

With such configuration, the plug-pin receiver is easily elastically deformed compared to the plug-pin receiver having no slits. Therefore, the elasticity of the plug-pin receiver can be ensured.

The single metal plate may include a substantially quadrangular portion forming the plug-pin receiver and another substantially rectangular portion forming the frame body, the plug-pin receiver and the frame body being formed by bending the corresponding substantially quadrangular portions, respectively.

The substantially quadrangular portion of the single metal plate which forms the plug-pin receiver may have a plurality of slits extending along the plug-pin insertion direction.

In accordance with another aspect of the present invention, there is provided a receptacle including the screw terminal described above.

With such configuration, the plug-pin receiver of the screw terminal is formed in the tubular shape and thus can be scaled down compared to the conventional plug-pin receiver. Hence, the receptacle can also be scaled down.

The receptacle may further include a peripheral wall insertion groove formed into a substantially quadrangular shape when viewed from the plug-pin insertion direction, a peripheral wall of the plug surrounding the plug pin being adapted to be inserted into the peripheral wall insertion groove; and a plug receiving part surrounded by the peripheral wall insertion groove and formed into a substantially quadrangular shape when viewed from the plug- pin insertion direction. The plug receiving part is provided with a plurality of plug-pin insertion holes disposed along a reference side that is one side of an outer periphery of the plug receiving part, each of the plug-pin insertion holes having a circular shape. The plug-pin insertion holes are disposed closer to the reference side than to an opposite side of the outer periphery of the plug receiving part in a direction perpendicular to the reference side .

With such configuration, the peripheral wall insertion groove has a substantially quadrangular shape, so that the insertion orientation of the peripheral wall of the plug is restricted compared to a case where the peripheral wall insertion groove has a round shape. Accordingly, an operator can easily recognize the plug insertion orientation, which is convenient in use. Further, the plug-pin insertion holes are arranged offset closer to the reference side than to the opposite side. Therefore, the reverse insertion of the plug into the receptacle can be prevented without forming a separate structure for preventing the reverse insertion at the peripheral wall insertion groove and the peripheral wall of the plug. Hence, the scaling up of the receptacle can be suppressed compared to a receptacle having a separate structure for preventing the reverse insertion.

In accordance with the present invention, it is possible to provide a screw terminal having a plug-pin receiver and an electrical wire connecting portion formed as one unit with ease and a receptacle including the screw terminal . Brief Description of the Drawings

The objects and features of the present invention will become apparent from the following description of embodiments, given in conjunction with the accompanying drawings, in which:

Figs. 1A to 1C show a receptacle in accordance with an embodiment of the present invention, wherein Fig. 1A is a perspective view showing a perspective structure of the receptacle, Fig. IB is a plan view showing a plan structure of the receptacle seen from the front, and Fig. 1C is a plan view showing a plan structure of the receptacle seen from the rear;

Fig. 2 is a perspective view showing an exploded perspective structure of the receptacle;

Figs. 3A to 3D show a screw terminal, wherein Fig. 3A is a perspective view showing an exploded perspective view of the screw terminal, Fig. 3B is a plan view showing a plan structure of the screw terminal seen from the rear, Fig. 3C is a plan view showing a plan structure of the screw terminal seen from the front, and Fig. 3D is a cross sectional view showing a cross sectional structure of the plug-pin receiver;

Figs. 4A to 4D are schematic perspective views showing processes of manufacturing a screw terminal by using a metal plate;

Fig. 5 is a cross sectional view showing a cross sectional structure of the receptacle;

Figs . 6A and 6B show a plug inserted into the receptacle, wherein Fig. 6A is a perspective view showing a perspective structure of the plug, and Fig. 6B is a plan view showing a front structure of the plug;

Figs. 7A and 7B show the receptacle and the plug, wherein Fig. 7A is a perspective view showing the insertion of the plug into the receptacle, and Fig. 7B is a plan view showing a plan structure of the receptacle and the positional relationship between plug-pin insertion holes and plug pins in case of reversely inserting the plug into the receptacle ;

Figs. 8A to 8C show a plug-pin receiving member and plug pins, wherein Fig. 8A is a cross sectional view showing a cross sectional structure in a state where the plug pins are inserted into the plug-pin receiver, Fig. 8B is a plan view showing a plan structure of the plug-pin receiver in a state where the plug pins are inserted into the plug-pin receiver, and Fig. 8C is a cross sectional view showing a cross sectional structure of the plug-pin receiver in a state where the plug pins are disconnected from the plug-pin receiver;

Figs. 9A and 9B are plan views showing a front structure of the receptacle installed on a wall surface;

Fig. 10 is a perspective view showing a perspective structure of a receptacle in accordance with another embodiment of the present invention;

Figs. 11A and 11B are perspective views showing an exploded perspective structure of a pillar member of the receptacle in accordance with another embodiment of the present invention;

Figs . 12A to 12D are plan views showing a plan structure of a receptacle as a comparative example; and Fig. 13 shows a conventional screw terminal, wherein Fig. 13A is a perspective view showing an exploded perspective structure of the screw terminal, and Fig. 13B is a perspective view showing another perspective structure of the screw terminal .

Detailed Description of the Embodiment

A receptacle in accordance with an embodiment of the present invention will be described in detail with reference to Figs. 1A to 9B, in which the receptacle is exemplified as- a wall-embedded DC receptacle.

A configuration of the receptacle 10 will be described with reference to Figs. 1A to 5. Hereafter, a long side direction of the receptacle 10 is defined as "a left-right direction Y" , and a short side direction thereof is defined as "an up-down direction Z." A direction perpendicular to both the left-right direction Y and the up-down direction Z is defined as "a front-rear direction X." In this embodiment, the front-rear direction X corresponds to the plug-pin insertion direction in which plug pins 44 (see Fig.

6) are inserted into the receptacle 10.

As shown in Fig. 1A, a body 11 and a cover 12, which are made of a synthetic resin by injection molding, are fixed with each other by a pair of metal assembly frames 13 to thereby form a body of the receptacle 10 with a substantially rectangular parallelepiped shape.

The receptacle 10 is designed to have a size conforming to Japanese Industrial Standards (see JIS C 8303) . Namely, the receptacle 10 is formed to have a size of one module dimensions (hereinafter, referred to as "a single module dimensions"), in which three receptacles with the single module dimensions can be accommodated in a mounting frame of a large rectangular string wiring accessory (see JIS C 8375) . Further, a front surface 12a of the cover 12 is formed to have a width HI in the left-right direction Y approximately the same as a width of the mounting frame with a rectangular shape in the left-right direction Y.

As shown in Fig. IB, the front surface 12a of the cover 12 includes: a peripheral wall insertion groove 14 recessed backwardly from the front surface 12a; and a plug receiving part 15 surrounded by the peripheral wall insertion groove 14. The peripheral wall insertion groove

14 is formed to have a substantially quadrangular shape whose two lower corners are cut away viewed from its front side. A front surface 15e of the plug receiving part is formed flush with the front surface 12a of the cover 12.

The peripheral wall insertion groove 14 includes: a pair of first insertion grooves 14a extending along the up- down direction Z; a pair of second insertion grooves 14b extending along the left-right direction Y; and a pair of inclination grooves 14c connecting the respective first insertion grooves 14a to the lower second insertion groove 14b located. The inclination grooves 14c are provided below the center line LI of the plug receiving part 15 in the up- down direction Z (at the middle of the plug receiving part

15 in the up-down direction Z) . Further, at a center portion of the lower second insertion groove 14b in the left-right direction Y, there is provided an extension groove 14d extending upwardly from the lower second insertion groove 14b.

The plug receiving part 15 has first sides 15a corresponding to the first insertion grooves 14a; second sides 15b corresponding to the second insertion grooves 14b; inclination sides 15c corresponding to the inclination grooves 14c ; and a recessed side 15d corresponding to the extension groove 14d. Each of the inclination side 15c is formed to extend in parallel to an opposite side 14e facing to the inclination side 15c, which constitutes a part of the inclination groove 14c.

Above the center position LI of the plug receiving part 15, a pair of plug-pin insertion holes 16 with a circular shape viewed from its front side is provided, which are extended through the plug receiving part in the front- rear direction X. Namely, supposed that the upper second side 15b is defined as a reference side KL, the plug-pin insertion holes 16 are disposed closer to the reference side KL than the lower second side 15b.

Meanwhile, the peripheral wall insertion groove 14 is formed to have different shapes depending on a type of a power supply circuit (not shown) serving as a power supply source. The power supply circuit is interposed between a DC power supplying section and the receptacle 10, and, for example, installed in a power distribution panel (not shown) The above power supply circuit has at least two kinds of circuits such as an ELV circuit (Extra-Low Voltage circuit) and a SELV circuit (Safety Extra-Low Voltage circuit) . The ELV and the SELV circuit are specified as IEC60950-1 and IEC60335-1 by IEC standards, respectively.

Electrical appliances, such as information equipment and lighting apparatuses, have different internal insulation structures depending on the ELV or the SELV circuit. In other words, an electrical appliance based on the ELV circuit requires a strict insulation structure, that is, adopts a double insulation structure or a reinforced insulation structure. On the other hand, an electrical appliance based on the SELV circuit may not adopt the double insulation structure or the reinforced insulation structure, thereby requiring more simplified insulation structures as compared with the electrical appliance according to the ELV circuit .

In the case where the electrical appliance based on the ELV circuit is connected to the receptacle 10 for the SELV circuit, there is no problem because the electrical appliance has the strict insulation structure. On the other hand, in the case where the electrical appliance based on the SELV circuit is connected to the receptacle for the ELV circuit, there is a problem such that the electrical appliance may be destroyed when a hazardous voltage is applied thereto because the electrical appliance has the simplified insulation structure. Accordingly, the receptacles 10 and the plugs 30 (see Fig. 6) , for the ELV circuit and for the SELV circuit, need to be distinguished from each other. Particularly, it is required to prevent the electrical appliance based on the SELV circuit from being connected to the receptacle for the ELV circuit by mistake .

Accordingly, in the present embodiment, as the cover 12 for the SELV circuit, the extension groove 14d is provided in the peripheral wall insertion groove 14. On the other hand, as a cover for the ELV circuit, the extension groove 14d is not provided in a peripheral wall insertion groove. Further, a plug 40 of the electrical appliance for the SELV circuit has a rib 45a in its peripheral wall 45. On the other hand, a plug of the electrical appliance for the ELV circuit has no rib 45a described above. Accordingly, the plug for the ELV circuit can be inserted into the peripheral wall insertion groove 14 for the SELV circuit, whereas the plug for the SELV circuit can not be inserted into the peripheral wall insertion groove for the ELV circuit. Accordingly, it can be prevented that the electrical appliance based on the SELV circuit is connected to the receptacle for the ELV circuit by mistake.

As shown in Fig. 1C, two electrical wire insertion holes lib through which an electrical wire (not shown) inserted are formed through a bottom wall 11a of the body 11 in the up-down direction Z. Moreover, a portion of the bottom wall 11a where the electrical wire insertion holes lib are formed protrudes rearward from the bottom wall 11a.

As shown in Fig. 2, two screw terminals 17 are accommodated in the inner space defined by the body 11 and the cover 12. Specifically, the body 11 has two terminal seat portions 11c adjacent to each other in the left-right direction Y. The terminal seat portions 11c penetrate a sidewall lid of the body 11 in the up-down direction Z and are opened at the front side. The screw terminals 17 are received in the terminal seat portions 11c.

The structure and the manufacturing process of the screw terminal 17 will be described with reference to Figs. 3A to 4D. In Figs. 3B and 3C, a screw member 22 is omitted. As shown in Fig. 3A, the screw terminal 17 includes a pillar member (electrical wire connection unit) 20 for connecting an electrical wire, a plug-pin receiver 21 for gripping the plug pin 34 of the plug 30, and the screw member 22 screwed into the pillar member 20. A single connecting portion 28 for connecting the pillar member 20 and the plug-pin receiver 21 is provided between the pillar member 20 and the plug-pin receiver 21. The screw terminal 17 of the present embodiment is formed by pressing a single copper plate having a thickness which ensures the elasticity of the plug-pin receiver 21.

The plug-pin receiver 21 has a substantially cylindrical part 21a extending from the front end portion of the connecting portion 28 in the front-rear direction X. The cylindrical part 21a is provided with three slits 23 extending in the front-rear direction X, so that the cylindrical part 21a is configured to have four gripping pieces 24. Specifically, when viewed from the front, the cylindrical part 21a has a substantially circular shape formed by combining the four arch-shaped gripping pieces 24

(see Fig. 3C) .

As shown in Fig. 3B, the pillar member 20 is formed by a surrounding wall having a rectangular shape whose long side is extended in the left-right direction Y when viewed from the rear. A screw fixing portion 25 into which the screw member 22 is screwed is formed at an upper wall 20a of the pillar member 20 by burring. The screw fixing portion 25 has a substantially cylindrical shape extending downward from the upper wall 20a. Further, a female thread is formed at the screw fixing portion 25 by screw processing. As shown in Fig. 3C, the plug-pin receiver 21 and the pillar member 20 are overlapped with each other in the up- down direction Z. In other words, the plug-pin receiver 21 is received in the pillar member 20 in the up-down direction Z. Accordingly, the screw terminal 17 can be scaled down compared to a case where the plug-pin receiver and the pillar member are offset when viewed in the up-down direction Z.

As shown in Fig. 3D, the front side of the plug-pin receiver 21 is provided with a plug-pin holding part 24a adapted to make contact with and hold the plug pin 34 (see Fig. 6) and an arc receiving part 24b extending forwardly from the plug-pin holding parts 24a. The plug-pin holding part 24a determines a minimum diameter Dmin of an inner diameter D of the plug-pin receiver 21. The arc receiving part 24b has an inclined surface 24c with a larger inner diameter as it goes forward. When the plug pin 34 is inserted into the plug-pin receiver 24, the plug pin 34 is guided to the plug-pin holding part 24a by the inclined surface 24c. Accordingly, the plug pin 34 can be easily inserted into the plug-pin receiver 21. Besides, due to the contact between the inclined surface 24c and the plug pin 34, the gripping pieces 24 can be easily elastically deformed away from each other.

Here, the arc receiving part 24b is formed to have a higher melting point than that of the other parts of the plug-pin holding part 24a. Specifically, the arc receiving parts 24b are plated with nickel tungsten.

Fig. 4A shows a sheet of metal plate M. The sheet is punched to form a developed shape of the pillar member 20, the plug-pin receiver 21 and the connecting portion 28 (see Fig. 4B) . Further, the pillar member 20 is provided with the screw fixing portion 25, and the plug-pin receiver 21 is provided with the slits 23 and the gripping pieces 24. As shown in Fig. 4C, each of the gripping pieces 24 is bent into an arch shape by bending work, and opposite side ends

26 of the plug-pin receiver 21 (cylindrical part 21a) are bent into a circle shape around the connecting portion 28 as indicated by arrows Rl . As a result, the plug-pin receiver 21 is made into a substantially cylindrical shape as shown in Fig. 4D. In the same manner, opposite side end portions

27 of the pillar member 20 are bent by bending work around the connecting portion 28 as indicated by arrows Rl . As a consequence, a frame body having a shape of a rectangular surrounding wall is formed. Here, the opposite side ends 26 of the plug-pin receiver 21 are separated from each other by a gap. Furthermore, the opposite side end portions 27 of the pillar member 20 are separated from each other by a gap while facing each other.

Position of the screw terminal 17 in the receptacle 10 will be described with reference to Fig. 5.

The pillar member 20 is received in the body 11 and is positioned below the cover 12. In other words, the pillar member 20 is located below the peripheral wall insertion groove 14.

Further, the plug-pin receiver 21 has a portion protruding frontward beyond the body 11 to be received in the cover 12. The plug-pin receiver 21 is received within an area surrounded by the peripheral wall insertion groove 14 (namely, the area corresponding to the plug receiving part 15 in the up-down direction Z and the left-right direction Y) and is partially overlapped with the peripheral wall insertion groove 14 in the front-rear direction X.

Hereinafter, connection and disconnection of the electrical wire to and from the receptacle 10 will be described .

When the electrical wire is connected to the receptacle 10, the electrical wire is inserted into the electrical wire insertion hole lib of the body 11 and then into the pillar member 20. In such state, the screw member 22 is firmly tightened, so that the electrical wire is clamped between a lower end surface 22a of the screw member 22 and an inner peripheral surface 20c of a lower wall 20b (see Figs. 3A and 3B) . As a consequence, the electrical wire is connected to the screw terminal 17, and the connection of the receptacle 10 and the electrical wire is completed. On the other hand, when the electrical wire is disconnected from the receptacle 10, the force to clamp the electrical wire is reduced by loosening the screw member 22. Then, the electrical wire is pulled out rearward and disconnected from the receptacle 10.

Hereinafter, with reference to Figs. 6A to 7B, a configuration of the plug 30 will be described, and connection and disconnection structures of the plug 30 to and from the receptacle 10 will be described with reference to Figs. 8A to 8C.

As shown in Fig. 6A, the plug 30 includes a cable 32, and a plug main body 31 connected to the cable 32. The plug main body 31 includes a surface 33 adapted to be opposite to the plug receiving part 15 (see Figs. 7A and 7B) in the front-rear direction X; two round plug pins 34 extending backwardly from the surface 33; and a peripheral wall 35 surrounding the plug pins 34 from outside. The peripheral wall 35 has the same shape as the peripheral wall insertion groove 14 (see Figs. 7A and 7B) . Further, rear ends of the plug pins 34 are located slightly forward of a rear end surface of the peripheral wall 35.

As shown in Fig. 6B, the plug pins 34 are positioned above a center line L2 in the up-down direction Z of the peripheral wall 35. Moreover, the plug pins 34 are arranged along the left-right direction Y. The plug pins 34 include a positive plug pin (e.g., left-hand side in Fig. 6B) and a negative plug pin (e.g., right-hand side in Fig. 6B) .

As shown in Fig. 7A, at the time when the plug 30 is inserted into the receptacle 10, the peripheral wall 35 is inserted into the peripheral wall insertion groove 14. Then, the plug pins 34 are inserted into the plug-pin insertion holes 16. The plug-pin insertion holes 16 include a positive plug-pin insertion hole for inserting the positive plug pin 34 and a negative plug-pin insertion hole for inserting the negative plug pin 34.

As shown in Fig. 7B, when the plug 30 would be reversely inserted into the receptacle 10, the plug pins 34 are positioned below the center line LI of the plug receiving part 15.

Accordingly, the plug pins 34 are brought into contact with the front surface 15e of the plug receiving part 15, thereby preventing the insertion of the plug 30 into the receptacle 10.

The expression "reverse insertion" indicates a state where the positive plug pin is inserted into the negative plug-pin insertion hole and the negative plug pin is inserted into the positive plug-pin insertion hole. When the plug is reversely inserted, an inappropriate voltage is applied to the plug pins 34, which may result in damage of an electric appliance connected to the plug pins 34.

Even if the reverse insertion of the plug pins 34 into the plug-pin insertion holes 16 is attempted, the reverse insertion can be reliably prevented because the plug-pin insertion holes 16 and the plug pins 34 are separated from each other in the up-down direction Z.

As shown in Fig. 8A, when the plug pin 34 is inserted into the plug-pin receiver 21, the plug-pin receivers 21 are elastically deformed away from each other as indicated by arrows Yl as a tip end part 34a of the plug pin 34 is moved from the arc receiving parts 24 to the plug-pin holding part 24a. Specifically, the gripping pieces 24 opposed to each other through the plug pins 34 in a diametric direction are elastically deformed away from each other as shown in Fig. 8A. Then, the plug pins 34 are held by a recovery force of the plug-pin receiver 21 (the recovery force of each gripping piece 24) . Moreover, the plug pins 34 are held by being in line contact with the four gripping pieces along the circumferential direction thereof .

On the other hand, as shown in Fig. 8C, when the plug

30 is disconnected from the receptacle 10, the gripping pieces 24 of the plug-pin receiver 21 are deformed to come closer to each other by their recovery forces as indicated by arrow Y2 as the tip end part 34a of the plug pin 34 is moved from the plug-pin holding part 24a to the arc receiving part 24b.

Further, when the plug pin 34 are pulled out from the plug-pin receivers 21, the plug-pin receivers 21 return to its initial state before the insertion of the plug pin 34.

When the plug pins 34 are moved from the plug-pin holding part 24a to the arc receiving parts 24b, arc may- occur between the plug pins 34 and the plug-pin receivers 21 The arc is received by the arc receiving parts 24b.

The variation in the arrangement of the receptacle 10 will be described with reference to Figs. 9A and 9B.

As shown in Fig. 9A, one receptacle 10 is installed at a mounting frame, and a decorative plate 40 is installed to the mounting frame from its front side. The decorative plate 40 has an opening hole 41 with the single module dimensions formed to expose the front surface 12a of the cover 12.

As shown in Fig. 9B, since the receptacle 10 is designed to have the single module dimensions, another receptacle 10 or other wiring accessories, which have the single module dimensions or double module dimensions standardized by Japanese Industrial Standards (e.g., an outlet 43 for coaxial cables and a modular jack 44 for telephone lines), can be installed at the mounting frame. In other words, the receptacle 10 and the above wiring accessories can be attached to the common mounting frame. Note that the decorative plate 40 is provided with the opening hole 42 having three-piece module dimensions. Besides, note that the above wiring accessories are not limited to the outlet 43 and the modular jack 44, other wiring accessories such as an AC receptacle and a modular jack for LAN cables may be employed.

In accordance with the screw terminal 17 and the receptacle 10 including the screw terminal 17 of the present embodiment, the following effects can be obtained.

(1) In accordance with the present embodiment, the pillar members 20 and the plug-pin receivers 21 are made from a single metal plate M. Therefore, the number of components of the terminal can be reduced compared to when the terminal and the plug-pin receivers are formed as separate members.

(2) In accordance with the present embodiment, the plug-pin receivers 21 are formed in a substantially cylindrical shape. Hence, the plug-pin receivers 21 can be scaled down in the up-down direction Z compared to the conventional plug-pin receiving member 230 shown in Fig. 13B. As a result, the receptacle 10 can be scaled down in the up- down direction Z .

Further, when the plug-pin receiving members 230 of Fig. 13B are scaled down in the up-down direction Z in order to scale down the receptacle in the up-down direction Z, the area of the holding surface 231 of the plug-pin receiving member 230 is reduced. Hence, the electrical resistance of the holding surface 231 is increased, and the amount of heat generated by electrical connection of the plug pin and the holding surface 231 is increased. Since, however, the plug- pin receiver 21 has a substantially cylindrical shape in the present embodiment, the reduction in the area for holding the plug pin 34 can be suppressed. Accordingly, the increase in the electrical resistance can be suppressed compared to the case of scaling down the conventional plug- pin receiving member 230 of Fig. 13B.

In the conventional plug-pin receiving member 230, the plug pin is held at two contact points and thus cannot be stably supported. To that end, in the present embodiment, the plug-pin receiver 21 is formed in a substantially cylindrical shape, so that the plug pin 34 can contact with the plug-pin receivers 21 along the circumferential direction thereof. Accordingly, the plug pin 34 can be stably held by the plug-pin receiver 21.

Especially, in the present embodiment, the receptacle

10 has the single module dimension, and the peripheral wall insertion groove 14 is formed at the cover 12. Therefore, a pair of plug-pin receivers 21 needs to be accommodated in an area surrounded by the peripheral wall insertion groove 14. However, the conventional plug-pin receiving member 230 has a large size in the up-down direction Z and thus cannot be accommodated in the area surrounded by the peripheral wall insertion groove 14. In the present embodiment, the plug- pin receiver 21 has a substantially cylindrical shape and is scaled down in the up-down direction Z, so that it is easy to accommodate the plug-pin receivers 21 in the area surrounded by the peripheral wall insertion groove 14. Besides, the pillar members 20 are arranged at positions lower than the peripheral wall insertion groove 14. Hence, even if the pillar members 20 are provided outside the peripheral wall insertion groove 14, the scaling up of the receptacle 10 can be suppressed.

Further, the plug-pin insertion holes 16 are positioned above the center line LI of the plug receiving part 15. In case of using the conventional plug-pin receiving member 230 shown in Fig. 13B, the plug-pin receiving member 230 needs to be accommodated in the area surrounded by the peripheral wall insertion groove, so that only the upper end portions of the plug-pin receiving member 230 are overlapped with the plug-pin insertion holes in the front-rear direction X. Accordingly, the plug pins are held only by the upper end portions of the plug-pin receiving member 230, which makes it difficult to stably support the plug pins 230 by the conventional plug-pin receiving member 230. On the other hand, in the present embodiment, the plug-pin receivers 21 having a substantially cylindrical shape extending in the front-rear direction X are formed at positions corresponding to the positions of the plug-pin insertion holes 16 and, hence, the plug pins 34 can be stably held.

(3) In accordance with the present embodiment, the screw fixing portion 25 is formed at the pillar member 20 by burring. As a consequence, the screw member 22 can be screwed into the pillar member 20.

In a general screw terminal having a pillar member, it is known that the pillar member and the plug-pin receiver are made from separate metal plates. This is because the pillar member requires a thick thickness to form a through hole at the pillar member and a female thread at the inner peripheral surface of the through hole. On the other hand, the plug-pin receiver requires an extremely thin thickness to ensure elasticity. For such reasons, the pillar member and the plug-pin receiver are separately provided. However, the pillar member and the plug-pin receiver provided as separate members result in the increase in the number of the components.

In this regard, in the present embodiment, the pillar member 20 and the plug-pin receiver 21 are made from a single metal plate M and, also, the screw fixing portion 25 is formed at the pillar member 20 by burring. Hence, even if the pillar member is made from a metal plate M having a thickness which ensures the elasticity of the plug-pin receiver 21, the screw member 22 can be screwed thereinto. To be specific, the screw fixing portion 25 is formed as a substantially cylindrical tapped hole, so that it is possible to ensure the area where the female thread is formed. Accordingly, the screw member 22 can be screwed into the screw fixing portion 25.

(4) In accordance with the present embodiment, the plug-pin receiver 21 is formed by bending. Thus, the elasticity of the plug-pin receivers 21 can be ensured compared to that formed by cutting. Moreover, the plug-pin receiver 21 can be easily formed compared to that formed by drawing .

(5) In accordance with the present embodiment, the plug-pin receiver 21 is provided with the slits 23. Therefore, the elasticity of the plug-pin receivers 21 is improved compared to that having no slits. Resultantly, the plug pins 34 can be stably held by the plug-pin receiver 21.

In addition, the contact area is increased compared to the conventional plug-pin receiving member 230 shown in Fig. 13B. Hence, the electrical connection of the plug-pin receivers 21 and the plug pins 34 can be ensured.

(6) In accordance with the present embodiment, the plug-pin receiver 21 has the arc receiving part 24b. Therefore, it is possible to reduce the effects of the arc on other components of the receptacle 10 such as the cover 12 and the like compared to the case of using the plug-pin receiver having no arc receiving part 24b.

Especially, in the present embodiment, the receptacle

10 is a DC receptacle, so that the arc is generated for a longer period of time compared to an AC receptacle and affects the plug-pin receiver 21, the cover 12 and the like. Since, however, the arc is received by the arc receiving part 24b, the effects of the arc on the other components can be reduced, which is preferable for a DC receptacle.

(7) In accordance with the present embodiment, the arc receiving part 24b has a higher melting point compared to the other parts of the plug-pin receiver 21. Hence, it is possible to prevent the arc receiving part 24b from being melted by the arc.

(8) In accordance with the present embodiment, the peripheral wall insertion groove 14 has a substantially quadrangular shape whose two lower corners are cut away. Therefore, the insertion orientation of the peripheral wall

35 into the plug 30 is restricted compared to the case of using the receptacle standardized by IEC standard which has the round peripheral wall insertion groove 111 shown in Figs 12A and 12B. Accordingly, an operator can easily recognize the insertion orientation of the plug 30 into the receptacle 10, which is convenient in use. Resultantly, the operator can easily insert the plug 30 into the receptacle 10 while avoiding the reverse insertion.

Further, the plug-pin insertion holes 16 are positioned above the center line LI in the outer periphery of the plug receiving part 15. Therefore, the reverse insertion of the plug 30 into the receptacle 10 can be prevented without providing a separate structure for preventing the reverse insertion to the peripheral wall insertion groove 14 and the peripheral wall 35. Accordingly, the scaling up of the receptacle 10 can be suppressed compared to the receptacle having the separate structure for preventing the reverse insertion.

Meanwhile, if the peripheral wall insertion groove 111 has an annular shape as shown in Fig. 12B, the following problem will be caused. That is, when the plug-pin insertion holes 112 are disposed on the upper half side in the circle, the distance between the plug-pin insertion holes 112 is reduced to decrease their dielectric strength. Further, when the peripheral wall insertion groove 111 of the receptacle 100 has a quadrangular shape and the plug-pin insertion holes 112 has a rectangular shape whose long side extends in the up-down direction Z as shown in Fig. 12C, it is necessary to scale up the receptacle 100 as shown in Fig. 12D in order to locate the plug-pin insertion holes 112 on the upper half side in the quadrangle.

In this regard, in the present embodiment, the plug- pin insertion holes 16 are formed in a circular shape while the peripheral wall insertion groove 14 is formed to have a quadrangular shape. Therefore, even if the plug-pin insertion holes 16 are positioned above the center line LI, the distance between the plug-pin insertion holes 16 is not reduced. Accordingly, the dielectric strength is improved compared to the receptacle 100 shown in Fig. 12B, and the scaling up of the receptacle 10 is not required unlike the receptacle 100 of Fig. 12B. Resultantly, the receptacle 10 can have the module dimension.

(9) In accordance with the present embodiment, the cylindrical part 21a and the pillar member 20 are bent with respect to the connecting portion 28 in the same directions indicated by arrows Rl and R2 (see Fig. 4C) . Hence, the cylindrical part 21a, the pillar member 20 and the connecting portion 28 can be easily formed compared to the case of bending the cylindrical part and the pillar member in, e.g., opposite directions. As a result, the screw terminal 17 can be easily manufactured.

(10) In accordance with the present embodiment, the ends 26 of the cylindrical part 21a are separated from each other. Thus, the elasticity of two gripping pieces 24 having the ends 26 separated from each other can be improved compared to the case where the ends 26 are connected to each other. As a consequence, the elasticity of the plug-pin receiver 21 can be ensured.

(11) In accordance with the present embodiment, the plug-pin receiver 21 is provided forwardly of the pillar member 20 and is provided at the same position as the pillar member 20 in the up-down direction Z and the left-right direction Y. Hence, the screw terminal 17 can be scaled down in the up-down direction Z compared to the conventional screw terminal 200 shown in Fig. 13B.

(12) In accordance with the present embodiment, the screw terminal 17 has one connecting portion 28 for connecting the plug-pin receiver 21 and the pillar member 20. Therefore, the bending of the plug-pin receiver 21, the pillar member 20 and the connecting portion 28 can be easily performed compared to the screw terminal having a plurality of connecting portions 28.

(13) In accordance with the present embodiment, the receptacle 10 has a size of the single module dimensions based on Japanese Industrial Standards, in which three receptacles with the single module dimensions can be accommodated in a mounting frame of a large rectangular string wiring accessory. Therefore, the receptacle 10 can be attached to a mounting frame of the other wiring accessories standardized by the same standards. Accordingly, there is no necessary to manufacture a dedicated mounting frame for the receptacle 10 independently, and the mounting frame can be used commonly. Consequently, the receptacle 10 can be attached to the mounting frame together with the other wiring accessories having the single module dimensions or the two-piece module dimensions, thereby improving its operability .

(14) In accordance with the present embodiment, the front surface 12a of the cover 12 and the front surface 15e of the plug receiving unit 15 are formed flush with each other in the front-rear direction X, and the plug pins 34 are configured to be located slightly forward of the rear end portion of the peripheral wall 35. With such configuration, when the plug 30 is reversely inserted into the receptacle 10, the plug pins 34 come into contact with the plug receiving part 15 before the peripheral wall 35 is excessively inserted into the peripheral wall insertion groove 14. Thus, an operator can easily recognize the reverse insertion, and the state in which the plug 30 is reversely inserted in the receptacle 10 cannot be maintained. Hence, the reverse insertion state cannot be maintained. (Other embodiments)

The receptacle 10 of the present invention is not limited to the above embodiment and can be modified as will be described below. Moreover, following modifications may be applied to the aforementioned embodiment, and the combination of the different modifications may also be possible .

In the above-described embodiment, a DC receptacle is employed as the receptacle 10. However, an AC receptacle to which an AC receptacle is supplied may be employed as the receptacle 10.

Although the plug-pin insertion holes 16 are positioned above the center line LI in the above-described embodiment, the plug-pin insertion holes 16 may be positioned at the same level as the center line LI or below the center line LI.

In the above-described embodiment, two inclined grooves 14c and one extension groove 14d are provided at the peripheral wall insertion groove 14. However, the shape of the peripheral wall insertion groove 14 is not limited to the above. For example, as shown in Fig. 10, the peripheral wall insertion groove 14 may have a substantially quadrangular shape in which the inclined grooves 14c and the extension groove 14d are omitted. In other words, the peripheral wall insertion groove 14 may have a quadrangular shape viewed from the front. In that case, the plug receiving part 15 is also formed in a substantially quadrangular shape viewed from the front. With such configuration, the aforementioned effect (8) can also be achieved .

Further, depending on the shape of the peripheral wall insertion groove 14, a type of supply voltage suitable for the receptacle 10 can be changed. Specifically, the shape of the peripheral wall insertion groove 14 shown in Fig. 10 may be suitable for the receptacle 10 of a supply voltage 24V, whereas the shape of the peripheral wall insertion groove 14 with a quadrangular shape whose both lower corners are cut away to provide the inclined grooves 14c may be suitable for the receptacle 10 of a supply voltage 48V. Further, the peripheral wall insertion groove 14 may have a quadrangular shape whose one lower corner is cut away to provide the inclined grooves 14c. This may be suitable for a receptacle of a supply voltage 12V or 6V, for example.

The peripheral wall insertion groove 14 and the plug receiving part 15 are not necessarily formed in a substantially quadrangular shape, and may be formed in a round shape. With such configuration, the aforementioned effect (1) can also be obtained.

Although the peripheral wall insertion groove 14 is provided at the cover 12 of the receptacle 10 in the above- described embodiment, the peripheral wall insertion groove 14 may be omitted. Hence, the peripheral wall 35 of the plug 30 which is inserted into the receptacle 10 is also omitted.

In the above-described embodiment, only the power plug-pin insertion holes 16 are formed in the plug receiving part 15. However, as shown in Fig. 10, a ground pin insertion hole 16a may also be formed in addition to the power plug-pin insertion holes 16. In that case, the ground pin insertion hole 16a is positioned below the center line LI and at the center in the left-right direction Y. In such configuration, there are provided three screw terminals 17 corresponding to the two plug-pin insertion holes 16 and the single ground insertion hole 16a, respectively.

In the above-described embodiment, the arc receiving part 24b is plated with nickel tungsten to have a higher melting point compared to the other parts of the plug-pin receiver 21. However, the configuration in which the arc receiving parts 24b have a higher melting point is not limited thereto. For example, by using clad material which is a metal plate of composite material, the arc receiving part 24b may be formed of a material having a higher melting point compared to the other parts. Specifically, for example, the arc receiving part 24b are made of tungsten and the other parts are made of copper.

Although the arc receiving part 24b is provided at the front side of the plug-pin holding part 24a in the above embodiment, the arc receiving part 24b may be omitted. For example, the front end portion of the plug-pin receiver 21 may have a higher melting point compared to the other portions .

In the above-described embodiment, the peripheral wall insertion groove 14 has a substantially rectangular shape whose long side extending in the left-right direction Y and short side extending in the up-down direction Z. However, the shape of the peripheral wall insertion groove 14 is not limited thereto.

The peripheral wall insertion groove 14 may be formed in a square shape having the same length in the left-right direction Y and the up-down direction Z.

Although the opposite side end portions 27 of the pillar member 20 are separated from each other in the above- described embodiment, the shape of the pillar member 20 is not limited thereto. As shown in Fig. 11A, the portion of the surrounding wall (lower wall 20b) , which is opposite to the screw member 22 in the up-down direction Z, may be formed by overlapping the side end portions 27 of the pillar member 20 with each other in the up-down direction Z. Accordingly, the lower wall 20b can be prevented from being deformed by the screw member 22 pressing the electrical wire against the lower wall 20b. Further, as shown in Fig. 11B, the screw fixing portion 25 may be formed after the opposite side end portions 27 of the pillar member 20 are overlapped with each other. In other words, the screw fixing portion 25 is provided at the portion of the pillar member 20 where side end portions of the metal plate M are overlapped. Accordingly, the burring work for forming the screw fixing portion 25 can be omitted.

In the above-described embodiment, the plug-pin insertion holes 16 have a round shape. However, the shape of the plug-pin insertion holes 16 is not limited thereto. For example, the plug-pin insertion holes 16 may be formed in a rectangular shape whose long side extends in the up- down direction Z and short side extends in the left-right direction Y. With such configuration, the aforementioned effect (1) can also be achieved.

In the above-described embodiment, the plug-pin receiver 21 has the cylindrical part 21a. However, the the plug-pin receiver 21 may have other tubular shapes than the cylindrical shape. For example, the plug-pin receiver may have a substantially square column shape viewed from the front. With such configuration, the aforementioned effect (2) can also be obtained.

While the invention has been shown and described with respect to the embodiments, it will be understood by those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.

Claims

What is claimed is:

1. A screw terminal comprising:

an electrical wire connecting portion to which an electrical wire is connected by a screw member; and

a plug-pin receiver for gripping a plug pin of a plug, wherein the electrical wire connecting portion and the plug-pin receiver are made from a single metal plate; the plug-pin receiver has a tubular shape extending along an insertion direction of the plug pin; and the electrical wire connecting portion is formed as a frame body opened along the plug-pin insertion direction.

2. The screw terminal of claim 1, further comprising a connecting portion for connecting the plug-pin receiver and the frame body, wherein the plug-pin receiver has a substantially cylindrical shape extending along the plug-pin insertion direction, and the electrical wire is firmly pressed against an inner peripheral surface of the frame body by tightening the screw member into the frame body.

3. The screw terminal of claim 2, wherein the frame body has a tapped hole into which the screw terminal is screwed, and the tapped hole is formed by burring.

4. The screw terminal of claim 2, wherein the frame body has a portion where side end portions of the metal plate are overlapped, and a tapped hole into which the screw member is screwed is formed at the portion.

5. The screw terminal of any one of claims 2 to 4 , wherein the plug-pin receiver has a plug-pin holding part which determine a minimum diameter of an inner diameter of the plug-pin receiver and a tip end part which extend from the plug-pin holding part along the plug-pin insertion direction, the tip end part having a gradually increased inner diameter.

6. The screw terminal of any one of claims 2 to 4 , wherein the tip end part of the plug-pin receiver has a higher melting point than that of portions other than the tip end part.

7. The screw terminal of any one of claims 2 to 4, wherein the plug-pin receiver has a plurality of gripping pieces formed by slits extending along the plug-pin insertion direction.

8. The screw terminal of any one of claims 2 to 4, wherein the single metal plate includes a substantially quadrangular portion forming the plug-pin receiver and another substantially rectangular portion forming the frame body, the plug-pin receiver and the frame body being formed by bending the corresponding substantially quadrangular portions, respectively.

9. The screw terminal of claim 8, wherein the substantially quadrangular portion of the single metal plate which forms the plug-pin receiver has a plurality of slits extending along the plug-pin insertion direction.

10. A receptacle comprising the screw terminal described in any one of claims 2 to 4.

11. The receptacle of claim 10, further comprising:

a peripheral wall insertion groove formed into a substantially quadrangular shape when viewed from the plug- pin insertion direction, a peripheral wall of the plug surrounding the plug pin being adapted to be inserted into the peripheral wall insertion groove; and

a plug receiving part surrounded by the peripheral wall insertion groove and formed into a substantially quadrangular shape when viewed from the plug-pin insertion direction,

wherein the plug receiving part is provided with a plurality of plug-pin insertion holes disposed along a reference side that is one side of an outer periphery of the plug receiving part, each of the plug-pin insertion holes having a circular shape, and

wherein the plug-pin insertion holes are disposed closer to the reference side than to an opposite side of the outer periphery of the plug receiving part in a direction perpendicular to the reference side.