Field of the Invention
The present invention relates to a plug receptacle to
which a plug is adapted to be connected, and including a
housing having an outlet unit for supplying DC power to the
plug and a cable connected to the housing.
Background of the Invention
Conventionally, there has been known a plug receptacle
having an outlet unit to which a plug of an electric device
such as a personal computer or a phone is detachably
connected to and serving to supply an operation power (AC
power) to the electric device through the plug, e.g., table
tap (see, e.g., Japanese Patent Application Publication No.
H07-211384 (JP07-211384A)).
In the meantime, most of electric devices make use of
direct current (DC) power as their drive power. For that
reason, the alternating current (AC) power supplied from an
AC outlet is converted to DC power by an AC-DC converter and
then fed to the electric devices. Power loss occurs when
the AC-DC converter converts the AC power to the DC power.
In%n effort to prevent such power loss, there is known a DC
outlet for supplying DC power to electric devices (see, e.g.,
Japanese Patent Application Publication No. H07-15835 (JP07-
15835A)). Use of the DC outlet makes it possible to omit an
AC-DC converter which would otherwise be provided between
the DC outlet and the electric devices. Two kinds pf plugs
usable with this DC outlet are known in the art, one of
which has a single plug pin as disclosed in JP07-1S835A and
the other of which has two plug pins complying with IEC
Standards.
In the plugs having two plug pins, the plug pins are
divided into a positive pin and a negative pin.
Correspondingly, the DC outlet is provided with a positive-
pin insertion hole into which the positive pin is inserted
and a negative-pin insertion hole into which the negative
pin is inserted. With the configuration of two plug pins
and two insertion holes, it is sometimes the case that the
positive pin is inserted into the negative-pin insertion
hole while the negative pin is inserted into the positive-
pin insertion hole (namely, reverse insertion occurs).
Taking this into account, the DC outlet is provided with a
structure for preventing the reverse insertion.
As compared with the AC outlet, it is likely in the DC
outlet that the arc generating between the DC outlet and the
plug becomes sustained if the plug is removed from the DC
outlet during power delivery. In order to make the arc
invisible from the outside of the plug, the plug is provided
with a surrounding wall for externally covering the plug
pins. As an example of the DC outlet having the surrounding
wall and the two plug pins, there is available a DC outlet
complying with IEC Standards.
Referring to Figs. 21A and 21B, description will be
made on a DC outlet and a plug complying with IEC Standards.
As shown in Fig. 21A, a plug 100 includes two positive
and negative plug pins 101 for electric connection with the
outlet unit of a DC outlet (hereinafter referred to as
"outlet unit 110") and a cylindrical surrounding wall 102
for externally covering the plug pins 101. A rib 103
protruding downwards is provided in the upper end portion of
the surrounding wall 102 along the vertical direction. The
plug pins 101 are arranged in the same position as the
center CR1 of the surrounding wall 102 in the vertical
direction and spaced apart from the center CR1 in the
horizontal direction.
As illustrated in Fig. 21B, the outlet unit 110
includes an insertion groove 111 into Which the surrounding
wall 102 is inserted and a plug-receiving portion 112
surrounded by the insertion groove 111. The insertion
groove 111 is formed into an annular shape in a plan view as
seen in the insertion direction of the plug 100. A keyway
113, into which the rib 103 is inserted, is provided in the
upper end portion of the insertion groove 111 along the
vertical direction. In the plug-receiving portion 112,
there are formed two pin insertion holes 114 into which the
plug pins 101 of the plug 100 are inserted. The pin
insertion holes 114 are arranged in the same position as the
center CR2 of the insertion groove 111 in the vertical
direction and spaced apart from the center CR2 in the
horizontal direction.
The plug 100 and the outlet unit 110 are connected to
each other by inserting the plug 100 into the outlet unit
110 in a state that the plug pins 101 are aligned with the
pin insertion holes 114, the surrounding wall 102 with the
insertion groove 111, and the rib 103 with the keyway 113.
In order to avoid reverse insertion of the plug 100
into the outlet unit 110, the plug 100 needs to be inserted
into the outlet unit 110 with the rib 103 of the plug 100
aligned with the keyway 113 of the outlet unit 110. In
other words, it is necessary for a user to align the rib 103
with the keyway 113 after the user visually confirms the
position of the rib 103 provided in the surrounding wall 102
of the plug 100. Thus, the task of inserting the plug 100
into the outlet unit 110 becomes cumbersome and onerous.
As another outlet structure for preventing reverse
insertion, it is thinkable to employ a configuration in
which, in place of omitting the rib 103, pin insertion holes
are provided in a position vertically off-centered from the
center of a plug-receiving portion as shown in Fig. 22A.
More specifically, as shown in Fig. 22A, an outlet unit 200
is provided with an insertion groove 201 having an annular
shape in a plan view as seen from the front side in the
front-back direction. Two pin insertion holes 203 are
provided at the upper side of the center CR3 of a circular
plug-receiving portion 202 surrounded by the insertion
groove 2 01.
However, the horizontal width of the plug-receiving
portion 202 grows smaller as the plug-receiving portion 202
extends upwards from the center CR3 in the vertical
direction. Thus, the distance DR1 joining the two pin
insertion holes 203 gets reduced. As a result, the distance
joining the plug pins (not shown) of the plug inserted into
the pin insertion holes 203 is reduced. This poses a
problem of reducing the dielectric strength of the plug pins.
As a solution to this problem, it is conceivable to
employ a configuration in which, as illustrated in Fig. 22B,
the size of the plug-receiving portion 112 is increased by
increasing the outer diameter DR2 of the insertion groove
201. This makes it possible to increase the distance DR5
between the two pin insertion holes 203 (so that DR5 becomes
greater than DR1).
In addition, the DC outlet may have a configuration in
which the pin insertion holes are in the form of rectangular
through-holes, into which the flat pins (not shown) of a
plug can be inserted, rather than circular through-holes.
More specifically, as shown in Fig. 23A, an outlet
unit 300 is provided with an insertion groove 301 having a
generally rectangular shape in a plan view as seen in the
front-back direction. Two pin insertion holes 303 are
provided at the upper side of the center GR 4 of a plug-
receiving portion 302 surrounded by the insertion groove 301
(wherein the center CR4 denotes the intersection point of
two diagonal lines joining four corners of the plug-
receiving portion 302) . The pin insertion holes 303 are
formed into a rectangular shape whose long side extends in
the vertical direction.
In case where the flat pins are formed to have the
same cross-sectional area as that of the plug pins, the
vertical dimension of the flat pins becomes greater than the
vertical dimension of the plug pins. Thus, the pin
insertion holes 303 are formed to extend long in the
vertical direction. More specifically, -the lower end
portions of the pin insertion holes 303 extend downwards
beyond the center CR4. Therefore, if the plug is reversely
inserted into the outlet unit 300, the flat pins partially
come xnto the pin insertion holes 303 and may possibly make
contact with the pin rest members (not shown) of the outlet
unit 300.
In view of this, it is conceivable to employ a
configuration in which, as shown in Fig. 23B, the size of
the plug-receiving portion 302 is increased by making the
outer dimensions DR3 and DR4 of the insertion groove 301
greater than those of the insertion groove 301 illustrated
in Fig. 23A. Thus, the entire portions of the pin insertion
holes 3 03 are positioned at the upper side of the center CR4
in the vertical direction, which makes it possible to
prevent reverse insertion. However, there is posed a
problem in that the increase in the size of the plug-
receiving portion 302 results in an increase in the size of
the outlet unit 300.
Summary of the Invention
In view of the above, the present invention provides a
DC outlet capable of preventing a plug from being reversely
inserted thereto without being scaled up and easily aligning
the plug therewith when the plug is connected thereto.
In accordance with an aspect of the present invention,
there is provided a plug receptacle comprising a housing
having at least one outlet unit to which a plug is adapted
to be connected to supply a DC power to the plug, the plug
including a plurality of plug pins having a circular bar
shape; and a substantially quadrangular-shaped surrounding
wall for surrounding the plug pins; and a cable, connected
to the housing, for supplying the DC power to the housing,
wherein: the outlet unit includes a plug-receiving portion
having a plurality of substantially circular pin-inserting
holes into which the plug pins of the plug are inserted, the
plug-receiving portion having a substantially quadrangular
shape viewed from a front side thereof; and an insertion
groove formed to surround a periphery of the plug-receiving
portion, the insertion groove being adapted to receive the
surrounding wall of the plug and having a substantially
quadrangular shape viewed from the front side; and the pin-
receiving holes are arranged along one side of the plug-
receiving portion serving as a reference side and offset
closer to the reference side than an opposite side to the
reference side.
A shape of at least one of the plug-receiving portion
and the insertion groove, viewed from the front thereof, may
be partially changed depending on the kinds of a supply
voltage or a supply current.
The shape of the insertion groove viewed from the
front may be changed such that an area of the plug-receiving
portion is decreased as compared with a case that the plug-
receiving portion has the substantially quadrangular shape
viewed from the front.
The shape of the insertion groove viewed from the
front may be changed differently depending on the kinds of
the supply voltage or the supply current by cutting at least
one side of the substantially quadrangular shape of the
plug-receiving portion depending on the kinds of the supply
voltage or the supply current, and forming the insertion
groove along an outer periphery of the plug-receiving
portion.
A portion of the insertion groove whose shape is
changed depending on the kinds of the supply voltage or the
supply current may be closer to the opposite side to the
reference side than the reference side.
The shape of the insertion groove viewed from the
front may be changed such that an area of the plug-receiving
portion is increased as compared with a case that the plug-
receiving portion has the substantially quadrangular shape
viewed from the front.
The shape of the insertion groove viewed from the
front may be changed by forming an extension groove
extending from the insertion groove. In this case, the
extension groove may be formed by extending a part of the
insertion groove into the plug-receiving portion, and the
extension groove may be provided closer to the opposite side
to the reference side of the plug-receiving portion than the
reference side.
Alternatively, the extension groove may be formed on
the front surface of the outlet main body' by outwardly
extending a part of the insertion groove.
A shape of at least one of the plug-receiving portion
and the insertion groove, viewed from the front thereof, may
be partially changed depending on the kinds of a power
supply circuit serving as a power supply source.
In this case, the shape of the insertion groove viewed
from the front may be partially changed only when the power
supply circuit is a safety extra low voltage (SELV) circuit.
The plug pins of the plug may include a ground pih, and the
pin-inserting holes of the plug-receiving portion may
include a ground pin inserting hole into which the ground
pin of the plug is inserted. In this case, the ground pin
inserting hole may be provided offset closer to the opposite
side to the reference side.
In accordance with embodiments of the present
invention, the outlet unit includes the plug-receiving
portion having the substantially quadrangular-shape viewed
from the front, the periphery of which is surrounded by the
insertion groove. In the plug-receiving portion, two pin-
inserting holes corresponding to the pin-receiving pieces
for supplying the DC power are arranged along one aide of
the plug-receiving portion serving as the reference side and
offset closer to the reference side of the plug-receiving
portion. Accordingly, it is possible to easily recognize an
orientation of the plug to be inserted into the outlet unit.
In addition, since the orientation of the plug to be
inserted into the outlet unit is restricted by the
substantially quadrangular-shaped surrounding wall of the
plug to be inserted into the insertion groove provided
around the substantially quadrangular-shaped plug-receiving
portion, it is possible to embody the DC outlet capable of
easily performing position alignment, preventing' the reverse
insertion, and being conveniently used. Further, the plug-
receiving portion has the substantially quadrangular-shape.
Accordingly, even when two pin-inserting holes are arranged
offset closer to the reference side, it is possible to
obtain a sufficient insulation distance without reducing the
distance between the pin-inserting holes, to thereby prevent
the DC outlet from being scaled up.
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:
Fig. 1 is a schematic view showing an information rack
employing a plug receptacle in accordance with a first
embodiment of the present invention;
Figs. 2A and 2B are a perspective view showing the
outer appearances of the plug receptacle or the lirst
embodiment and a front view of an outlet of the plug
receptacle, respectively;
Fig. 3A shows front, side and bottom views of the plug
receptacle and Fig. 3B is a plan view showing the internal
structure of the plug receptacle;
Fig. 4 is a perspective view showing a plug to be
connected to the plug receptacle;
Figs. 5A to 5D are a front view, a side view, a top
view and a partial cross sections view of the plug;
Figs. 6A and 6B are a perspective view showing a
connection relationship between Lhe plug receptacle and the
plug and a front view showing the state in which the plugs
are connected to the plug receptacle;
Figs. 7A to 7C are sectional view respectively showing
a state before the plug is connected to the plug receptacle,
a state of the plug being connected to the plug receptacle
and a state in which the plug is connected to the plug
receptacle;
Fig. 8A is a sectional view showing a state in which
the plug is connected to the plug receptacle. Figs. 8B and
8C are sectional views showing states the plug is being
disconnected from the plug receptacle while a lock portion
of the plug is pressed by the fingers, and Fig. 8D is a
sectional view showing a state in which the plug is
disconnected from the plug receptacle;
Fig. 9 is a front view of the plug receptacle which
explains a case that the plug is reversely inserted into the
plug receptacle;
Fig. 10 is a front view of an outlet unit of the plug
receptacle, which shows the change of the shape of the
outlet unit depending on the kinds of supply voltage;
Fig. 11 is a plan view of the plug receptacle in which
the outlet units of various shapes are arranged;
Fig. 12 is a schematic diagram showing a structure of
a DC power distribution system employing a plug receptacle
in accordance with a second embodiment of the present
invention;
Fig. 13 shows a perspective view of the plug
receptacle of the second embodiment;
Fig. 14 is a front view showing the shape of the
outlet unit of the plug receptacle depending on the kinds of
power supply circuit;
Fig. 15 is a plan view showing the plug' receptacle in
which the outlet units of various shapes are arranged;
Figs. i€A and 16B are front views showing
modifxcations of the shape of the outlet unit;
Fig. 17 is a plan view of the plug receptacle in which
the outlet units of various shapes are arranged;
Figs. 18A to 18C are front views showing the shapes of
the outlet unit of the plug receptacle depending on the
kinds of supply current;
Fig. 19 shows a front view of an outlet unit as a
comparative example;
Fig. 20A and 20B are front views showing outlet units
as another comparative example;
Figs. 21A and 21B are front views of a plug and an
outlet unit of a conventional plug receptacle, respectively;
Figs. 22A and 22B show front views of an outlet unit
of a plug receptacle as reference examples; and
Figs. 23A and 23B show front views of an outlet unit
of a plug receptacle as reference examples.
Detailed Description of the Embodiments
(First Embodiment)
There will be described a plug receptacle in
accordance with a first embodiment of the present invention
which is embodied as an outlet attached to an information
rack for accommodating a server device or the like with
reference to Figs. 1 to 11.
First of all, the relation between an information rack
JR and a plug receptacle 1 and a power supply structure of
the plug receptacle 1 will be described with reference to
Fig. l. In Figs. 3 to 11, a cable 1C of the plug receptacle
1 is omitted, and a plug 2 is omitted in Fig. 2.
As shown in Fig. 1, the information rack JR is formed
in a box shape by a frame body J1 forming an outer frame
thereof. The information rack JR includes an accommodating
section JS having an open front portion and serving as a
space for accommodating a server device (not shown).
Further, the information rack JR includes a partition member
J2 for partitioning the accommodating section JS into an
upper accommodating section JS1 and a lower accommodating
section JS2 in an up-down direction.
The frame body Jl has an outer frame body Jll forming
an outer part of the information rack JR and an inner frame
body J12 defining the accommodating section JS, the inner
frame body J12 being disposed inwardly of the outer frame
body Jll while being spaced from the outer frame body Jll at
a predetermined distance. A substantially flat plate-shaped
outlet attachment member J13 extending in the up-down
direction is provided between the outer frame body Jll and
the inner frame body J12.
The plug receptacle 1 of this embodiment is attached
to a lower portion of the outlet attachment member J13. To
be specific, the plug receptacle 1 is attached to the
information rack JR by inserting screws SCI into upper and
lower screw insertion through-holes ID and IE respectively
formed at an upper and a lower portion of the plug
receptacle 1 and then fixing the screws SCI to the outlet
attachment member J13.
AC power from an AC power supply AC as a commercial
power supply is converted into DC power by an AC/DC
converter BR1 of a power distributor BR; and the DC power
thus obtained is supplied to the plug receptacle 1. Further,
the power distributor BR and the plug receptacle 1 are
connected to each other by the cable 1C. Accordingly, the
DC power is supplied through the cable 1C to a power feeding
member IB (see Fig. 3B) provided inside the plug receptacle
l. Moreover, the DC power is supplied to a server device by
connecting a plug (not shown) of the server device to the
plug receptacle 1. The cable 1C has two electrode wires and
a single ground wire.
Hereinafter, the configuration of the plug receptacle
1 will be explained with reference to Figs'. 2 and 3.
As depicted in Fig. 2A, the plug receptacle 1
includes: a substantially rectangular parallelepiped-shaped
housing 1A forming an outer frame thereof; the power supply
member IB (see Fig. 3B) accommodated in the housing 1A; and
the cable 1C for supplying DC power to the power supply
member IB. In the following description,, a direction in
which the plug 2 is inserted into the plug receptacle 1 is
defined as a front-rear direction; a longitudinal direction
of the housing 1A is defined as an up-down direction; and a
width direction of the housing 1A is defined as a left-right
direction. Further, a side where the plug 2 is positioned
is defined as a front side, and a side where the plug
receptacle l is positioned is defined as- a rear side. The
up-down direction and the left-right direction are
perpendicular to each other.
The housing 1A includes: a substantially box-shaped
body 10 having an open front portion and formed by injection
molding using a resin material; and a substantially box-
shaped cover 20 having an open rear portion and formed by
injection molding using a resin material. Moreover, an
inner space defined by the body 10 and the cover 20
accommodates therein the power supply member IB adapted to
be connected to the plug 2 to supply DC power thereto.
The cover 20 has a. first cover 20A provided with six
outlet units 22 arranged along the up-down direction, and a
second cover 20B for covering a cable connection portion 11
(see Fig. 3B) from the front side, the cable connection
portion 11 being connected to the cable 1C. The DC power
plugs 2 are, e.g., detachably connected to the outlet units
22.
As illustrated in Fig. 2B, the outlet unit 22 has an
insertion groove 23 recessed rearward from a front surface
22a of the , outlet unit 22. The insertion groove 23 has a
shape in which lower right and left corners of a
substantially quadrangular shape viewed from the front side
are cut. To be specific, the lower right and left corners
of the insertion groove 23 are cut to have inclined sections
23a. A portion surrounded by the insertion groove 23 serves
as a plug-receiving portion 24 having a front surface 24a
positioned on the same plane as the front surface 22a in the
front-rear direction. An outer periphery'" of the plug-
receiving portion 24 has a shape in which lower right and
left corners of a substantially quadrangular shape viewed
from the front side are cut in accordance with the shape of
the insertion groove 23. Moreover, three pin insertion
holes 25 are formed at the plug-receiving portion 24. These
pin insertion holes 25 are circular through-holes as viewed
from the front.
The pin insertion holes 25 include two electrode-pin
insertion holes 25A and a single ground-pin insertion hole
25B. The electrode-pin insertion holes 25A are arranged
along a reference side 24b corresponding to one side
(extending in the left-right direction)... of the outer
periphery of the plug-receiving portion 24, i.e., the upper
side of the plug-receiving portion 24. The ground-pin
insertion hole 25B is disposed offset closer to a side
opposite to the reference side 24b than to the reference
side 24b, compared to those of the electrode-pin insertion
holes 2 5A. In other words, the position of the ground-pin
insertion hole 25B is lower than that of the electrode-pin
insertion holes 25A.
To be more specific, the electrode-pin insertion holes
25A are arranged offset closer to the reference side 24b
than to the side 24c of the plug-receiving portion 24. That
is, the electrode-pin insertion holes 25A are disposed above
the center C1 (i.e., an intersection point of diagonal lines
(dash-dotted lines) of the plug-receiving portion 24 in the
up-down direction. Further, the electrode-pin insertion
holes 2 5A are located at left and right sides of the center
Cl. Especially, lower ends 25a of the electrode-pin
insertion holes 25A which face the side 24c are positioned
closer to the reference side 24b than to the side 24c, i.e.,
above the central line L1 (dashed double-dotted line)
passing through the center Cl.
The ground-pin insertion hole 25B is offset downward
from the center Cl. Further, the ground-pin insertion hole
2 5B is located at the central position between the two
electrode-pin insertion holes 25A in the left-right
direction. In other words, the ground-pin insertion hole
2SB and the center Cl are positioned corresponding to each
other in the up-down direction. Especially, an upper end
25b of the ground-pin insertion hole 25B is positioned
closer to the side 24c than to the reference side 24b, i.e.,
below the central line L1.
The inclined sections 23a are provided only below the
straight line L1, so that it is possible to obtain a
sufficient distance between the inclined sections 23a and
the electrode-pin insertion holes 25A compared, to a case
that the inclined sections are provided above the central
line L1.
The upper part of the plug-receiving portion 24 has
substantially the same horizontal widtja HI (see Fig. 2B) .
Thus, even when the two electrode-pin insertion holes 25A
are offset upward from the center CI, scaling up of the
outlet unit 22 is not required. This can suppress scaling
up of an outlet unit 200 shown in Fig. 22B.
In addition, as illustrated in Fig. 23A, a single
ground-pin insertion hole 304 is formed at a lower portion
of a plug-receiving portion 302 of an outlet unit 300. The
ground-pin insertion hole 304 has a vertically elongated
rectangular shape and is located at the horizontal central
position between two electrode-pin insertion holes 303.
In order to obtain the ground-pin insertion hole 304
having the same area as that of the ground-pin insertion
hole 2 5B of this embodiment, an upper portion of the ground-
pin insertion hole 304 is extended upward from the center
CR4. Hence, the electrode-pin insertion holes 303 and the
ground-pin insertion hole 304 are partially positioned at
the same horizontal level. This decreases a minimum
horizontal distance DR6 between the ground-pin insertion
hole 304 and each of the electrode-pin insertion holes 303.
That is, electrode pins and a ground pin (all not shown) of
the plug are arranged adjacent to each other.
Hence, the plug-receiving portion 302 can be scaled up
by increasing outer diameters DR3 and DR4 of the insertion
groove 301, as shown in Fig. 23B. In this configuration,
the distance DR6 can increase compared to that in the outlet
unit 300 shown in Fig. 23A.
In the above configuration of Fig. 23B, the outlet
unit 300 is scaled up.
However, in this embodiment, the electrode-pin
insertion holes 25A are formed in a circular shape, so that
a vertical width thereof can decrease compared to that of
the electrode-pin insertion hole 303. Thus, the electrode-
pin insertion holes 25A can be formed above the center C1 of
the plug-receiving portion 24 without scaling up the outlet
unit 22.
Further, the ground-pin insertion hole 25B is formed
in a circular shape, so that a vertical width thereof can
decrease compared to that of the ground-pin insertion hole
3 04. For that reason, the ground-pin insertion hole 25B can
be formed below the center C1 of the plug-receiving portion
24 without scaling up of the outlet unit 22. Due to the
positional relation between the electrode-pin insertion
holes 2 5A and the ground-pin insertion hole 25B, the minimum
distance between each of the electrode-pin insertion holes
25A and the ground-pin insertion hole 25B can increase
compared to the distance DR6 (see Fig. 23A) between the
ground-pin insertion hole 304 and each of the electrode-pin
insertion holes 303. This allows the minimum distance
between each of the electrode pins 51A and the ground pin
51B (see Fig. 4) to increase compared to that in a plug
corresponding to the outlet unit 300.
As illustrated in Fig. 3A, the outlet unit 22 is
disposed such that the electrode-pin insertion holes 25A are
placed at an upper portion and the ground-pin insertion hole
25B is placed at a lower portion. Moreover, the electrode-
pin insertion holes 25A and the ground-pin insertion hole
2 5B of all the outlet units 22 are located at the same level
in the left-right direction.
Formed at the lower end portion of the housing 1A is a
cable insertion through-hole 1F which penetrates the housing
1A in the up-down direction and allows the cable 1C (see Fig.
1) to extend therethrough.
As can be seen from Fig. 3B, the power supply member
1B includes: a cable connection unit 11 connected to the
cable 1C; a pin-receiving piece connection portion 12
connected to the cable connection unit 11; and a pin-
receiving piece 13 connected to the pin-receiving piece
connection portion 12.
The cable connection unit 11 has a first connection
unit 11a connected to the cable 1C and a second connection
unit 11b having three wires for connecting the first
connection unit lla and the pin-receiving piece connection
portion 12. The first connection unit lla has two electrode
connection portions Hal and a ground connection portion
Ha2 provided between the two electrode "connection portions
Hal.
The pin-receiving piece connection portion 12 includes
three flat copper plates spaced from each other in the left-
right direction and extending in the up-down direction. The
lower end portion of the pin-receiving piece connection
portion 12 is connected to the second connection unit 11b.
The pin-receiving pieces 13 are arranged to correspond
to the electrode-pin insertion holes 25A and the ground-pin
insertion hole 25B of the outlet unit 22; and are connected
to the pin-receiving piece connection portion 12. To be
specific, six pin-receiving pieces 13 spaced from each other
at a predetermined gap in the up-down direction are
connected to the pin-receiving piece connection portion 12.
Hereinafter, the configuration of the plug 2 will be
described with reference to Figs. 4 and 5.
As shown in Fig. 4, the plug 2 includes a cable 2A and
a plug main body 2B connected to the cable 2A. The plug
main body 2B has a case formed by injection molding using a
resin material, a connection member (not shown) accommodated
in the case 50 and supplied with power through the cable 2A,
and plug pins 51 connected to the connection member.
The case 50 includes a first case 52, a second case 53
and a surrounding wall 54 arranged in that order from the
front side toward the rear side.
The first case 52 accommodates therein a part of the
cable 2A and the connection member. The cable 2A extends
frontward from a front end surface of the first case 52.
The second case 53 is fixed to the first case 52 by
screws SC2 and accommodates therein front portions of the
plug pins 51.
The surrounding wall 54 extends rearward from a rear
end surface of the second case 53. The "second case 53 and
the surrounding wall 54 are formed as a unit. The
surrounding wall 54 surrounds the plug pins 51 from the
outer side thereof. To be specific, the surrounding wall 54
has a shape in which lower right and left corners of a
substantially quadrangular shape viewed from the rear side
are cut. To be more specific, the lower right and left
corners of the surrounding wall 54 are cut to have inclined
sections 54a. Locking units 55 to be engaged with the
outlet unit 22 are provided at both side surfaces of the
second case 53.
Each of the locking units 55 includes a pressing
portion 55a, a connection portion 55b and an engagement
portion 55c arranged in that order from the front side
toward the rear side. The locking units 55 are connected to
the surrounding wall 54. In other words, the surrounding
wall 54 and the locking units 55 are formed in a single
member.
As shown in Fig. 5A, the plug pins 51 include: two
electrode pins 51A arranged along a side (extending in the
left-right direction) of a surface 50a of the second case 53
which faces the outlet unit 22 (see Fig. 2) of the plug
receptacle 1; and a single ground pin 51B positioned below
the electrode pins 51A. The electrode pins: 51A do not
protrude beyond the leading end of the surrounding wall 54..
The ground pin 51B protrudes slightly beyond the leading end
of the surrounding wall 54.
The electrode pins 51A are positioned above the center
C2 (i.e., an intersection point of diagonal lines (dashed
dotted lines) of the surrounding wall 54. ... Further, the
electrode pins 51A are formed at both sides of the center C2
in the left-right direction. Especially, lower ends 5la of
the electrode pins 51A are positioned above the central line
L2 (dashed double-dotted line) passing through the center CI.
The ground pin 5IB is provided below the center C2.
Further, the ground pin 51B is located at the central
position (in the left-right direction) between the two
electrode pins 51A (i.e., at the same level as the center C2
in the left-right direction). Especially, an upper end 51b
of the ground pin 51B is positioned below the central line
L2.
As shown in Fig. 5B, recesses 52a depressed frontward
are formed at rear end portions of both side surfaces of the
first case 52, and protrusion 53a to be engaged with the
recesses 52a are formed at front end portions of both side
surfaces of the second case 53. The locking units 55 and
the protrusions 53a are located at the same height level.
Cutoff portions 53b for accommodating the pressing
portions 55a and the connection portions 55b are provided at
both side surfaces of the second case 53. A vertical width
of the cutoff portions 53b is set to be greater than those
of the pressing portions 55a and the connection portions 55b.
Cutoff portions 54b for accommodating the engagement
portions 55c are provided at both side surfaces of the
surrounding wall 54. Further, locking unit connection
portions 54c to be connected to the engagement portions 55c
are disposed at rear end portions of both side surfaces of
the surrounding wall 54. •
A vertical width of the connection portions 55b is set
to be greater than that of the pressing portions 55a.
Moreover, a vertical width of the engagement portions 55c is
set to be greater than that of the connection portions 55b.
As can be seen from Fig. 5C, the pressing portions 55a
protrude from both side surfaces of the second case 53. To
be specific, each of the pressing portions- 55a has an
inclined outer surface which is gradually separated from the
corresponding side surface or the second case 53.
Each of the engagement portions 55c includes a first
inclined section SScl, a second inclined section S5c2 and a
third inclined section 5Sc3 arranged in that order from the
rear side toward the front side. The .first inclined
sections 55cl are connected to the locking unit connection
portions 54c. Further, the first inclined sections 55cl are
inclined toward the front side to be gradually separated
from both side surfaces of the surrounding wall 54.
The second inclined sections 55c2 are connected to
front end portions of the first inclined sections 55cl. In
addition, the second inclined sections 55c2 are inclined
toward the front side so as to be gradually widened outward.
An inclined angle a2 of the second inclined section 55c2 is
different from an inclined angle al of the first inclined
section 55cl. To be specific, the inclined angle a2 is set
to be greater than the inclined angle al.
The third inclined sections 5Sc3 are" connected to
front end portions of the second inclined s-ections 55c2 and
both sides of the connection portions 55b (see Fig. SB) .
Moreover, the third inclined sections 55e-3 are inclined
toward the front side so as to be gradually widened outward.
An inclined angle and then pulls the plug
forward (Pig. 8C) . Accordingly, the plug 2 is separated
from the plug receptacle l (Fig. 8D). The detailed
description thereof will be described hereinafter.
In order to separate the plug 2 from the plug
receptacle 1, an operator grips the pressing portions 55a of
the plug 2 as shown in Fig. 8A, and then presses the
pressing portions 55a inward as illustrated in Fig. 8B.
Accordingly, the pressing portions 55a and the connection
portions 55b are elastically deformed, and this allows
inward elastic deformation of the engagement portions 55c.
In that state, the surfaces 55c4 of the second inclined
sections 55c2 of the engagement portions 55c are positioned
inwardly of the facing surfaces of the insertion groove 23.
in other words, the surfaces 55c4 and the facing surfaces
are not overlapped with each other in the front-back
direction. Next, the operator pulls the plug 2. forward as
depicted in Fig. 8C, so that the engagement portions 55c are
separated fxoTn the surrounding wall holding portions 26.
Thereafter, as can be seen from Fig. 8D, the operator pulls
the plug 2 further forward so as to separate the surrounding
wall 54 and the plug pins 51 from the insertion groove 23
and the pin insertion holes 25.
Hereinafter, reverse insertion of the plug 2 into the
plug receptacle 1 will be described with reference to Fig. 9.
As illustrated in Fig. 9, when the plug 2 is reversely
inserted into the plug receptacle 1, the electrode pins 51A
of the plug 2 are located below the center'ci of the plug-
receiving portion 24 in the up-down direction, and the
ground pin 51B is placed above the center CI in the up-down
direction. Hence, the electrode pins 51A and the ground pin
51B contact with the front surface 24a of the plug-receiving
portion 24, and the plug 2 cannot be inserted into the plug
receptacle 1.
In that state, the electrode-pin insertion holes 25A
and the electrode pins 51A are misaligned with each other in
the up-down direction, and the ground-pin insertion hole 25B
and the ground pin 51B are misaligned with each other in the
up-down direction. Accordingly, the reverse insertion of
the plug pins 51 into the pin insertion holes 25 can be
reliably prevented.
Hereinafter, shapes of the outlet unit 22 depending on
the kinds of supply voltages will be described with
reference to Fig. 10.
There is a plurality of electric devices requiring
supply voltages, e.g., '6, 12, 24, 48 V, and the electric
devices are operated when being connected with the plug
receptacle 1. In this embodiment, the inse-rtion groove 23
and the plug-receiving portion 24 have a substantially
quadrangular shape viewed from the front side, and at least
one corner of the substantially quadrangular shape is cut
depending on the kinds of supply voltages, which allows the
outlet unit 22 to be identified. To be specific, at least
one corner of the insertion groove 23 is cut to have an
inclined section 23a depending on the supply voltages of 6V,
12V, 24V and 48V. Further, corners of the plug-receiving
portion 24 corresponding to the inclined sections 23a are
cut. ld have inclined sections.
The surrounding wall 54 of the plug- 2 has an inclined
section of inclined sections in accordance with1 the shape of
the insertion groove 23, which allows the plug 2 to be
identified depending on the kinds of supply voltages. The
plug 2 cannot be inserted into the plug receptacle 1 unless
the shape of the surrounding wall 54 of the plug 2 is
identical with that of the insertion groove 23 of the outlet
unit 22. Thus, the plug 2 and the plug receptacle 22 which
are used for different supply voltages cannot be connected
to each otner.
In the outlet unit 400 standardized by IEC standard,
four cutoff grooves 404 to 407 are formed depending on the
kinds of supply voltages, as illustrated in Fig. 19. To be
specific, the outlet unit 400 has an insertion groove 401
formed in a round ring shape viewed from the front side. A
plug-receiving portion 402 surrounded by the insertion
groove 401 has pin insertion holes 403 into which plug pins
(not shown) of the plug are inserted. The cutoff grooves
4 04 to 407 recessed inward from the insertion groove 4 01 are
formed at a lower portion of an outer periphery of the plug-
receiving portion 402. Moreover, a cutoff groove 408 for
preventing reverse insertion of the plug is formed at an
upper portion of the outer periphery of the plug-receiving
portion 402.
The cutoff grooves 404 to 407 respectively correspond
to the supply voltages of 6V, 12V, 24V and 48V, and are
spaced from the cutoff groove 408 at angles of 120°, 150°,
210° and 240° in the clockwise direction. Further, the plug
has an identifying rib corresponding to the cutoff groves
404 co 407. By inserting the identifying rib into the
corresponding one of the cutoff grooves 404 to 407, the plug
for the same supply voltage ae that of the outlet unit 400
can be inserted into the corresponding outlet unit 400.
Since, however, the cutoff grooves, 404 to 407 are
formed near the pin insertion holes 403, the strength of the
plug-receiving portion 402 decreases. Moreover, the
identifying rib is formed at the inner surface of the
surrounding wall, so that it is difficult for an operator to
check the position of the identifying rib from the front
side of the plug. Therefore, in order to insert the plug
into the outlet unit 400, the operator should check the
position of the identifying rib from the rear side of the
plug and align the identifying rib of the plug with the
corresponding one of the cutoff portions 404 to 407 of the
outlet unit 400. For that reason, the operation of
inserting the plug into the outlet unit 400 becomes
complicated.
In this embodiment, the inclined sections 23a are
provided at the lower corners of the insertion groove 23, so
that it is possible to obtain a sufficient distance between
the inclined sections 23a and the pin insertion holes 25
compared to the configuration of the outlet unit 400. This
can suppress decrea.se in strength of the. plug-receiving
portion 24 compared to the configuration of the outlet unit
400.
Besides, the shape of the surrounding wall 54 of the
plug 2 is changed depending on the kinds of -supply voltages,
so that the alignment position between the plug 2 and the
outlet unit 22 can be visually checked from the front side
of the plug 2. As a consequence, the plug 2 can be easily
inserted into the outlet unit 22.
As shown in Fig. 11, the outlet units 22 having the
various shapes in accordance with the kinds of supply
voltages are arranged on the plug receptacle 1. Accordingly,
the plug receptacle l can be used for various supply
voltages. The combination of the outlet units 22 may vary
without being limited to that shown in Fig. 11.
The plug receptacle 1 of this embodiment can provide
the following effects.
(l) in this embodiment, the insertion groove 23 of the
outlet unit 22 has a' substantially quadrangular shape, so
that the or-ientation of the plug 2 to be inserted into the
surrounding wall 54 is limited compared to the case that the
insertion grooves 111 and 201 have a round ring shape as
shown in Figs. 21B, 22A and 22B. This enables an operator
to easily recognize the insertion orientation of the plug 2
into the outlet unit 22, which is convenient in use.
Accordingly, the operator can easily insert the plug 2 into
the plug receptacle 1 while avoiding reverse insertion.
Moreover, the electrode-pin insertion holes- 25A are
provided above the center c1, and the ground-pin insertion
hole 25B is provided below the center C1. Thus, the reverse
insertion of the plug 2 into the plug receptacle 1 can be
prevented without forming a reverse insertion preventing
structure at the insertion groove 23 and the surrounding
wall 54. Accordingly, scaling up of the plug receptacle 1
can be suppressed compared to the case' that the plug
receptacle is provided with a reverse insertion preventing
structure.
In addition, the electrode-pin insertion holes 25A and
the ground-pin insertion hole 25B have a circular shape, so
that the minimum distance between the ground-pin insertion
hole 25B and each of the electrode-pin insertion holes 25A
can increase compared to the case that the electrode-pin
insertion holes 25A and the ground-pin insertion hole 25B
have a rectangular shape as shown in Figs. 23A and 23B.
Hence, insulation strength can be improved without scaling
up the outlet unit 22 compared to the case that the
electrode-pin insertion holes 2SA and the ground-pin
insertion hole 25B are formed in a rectangular shape.
Besides, since the ground-pin insertion hole 25B is
formed at the outlet unit 22, the plug receptacle 1 can
correspond to the plug 2 having the ground pin 5IB as well
as the plug 2 having no ground pin.
(2) In this embodiment, the ground-pin insertion hole
2 5B is located below the electrode-pin insertion holes 25A
in the up-down direction, so that the minimum distance
between the electrode-pin insertion holes 25A and the
ground-pin insertion hole 25B of the plug-receiving portion
2 4 can increase compared to the case that the electrode-pin
insertion holes and the ground-pin insertion hole are
located at the substantially same height level. Accordingly,
it is possible to increase an insulation distance between
the electrode-pin insertion holes 25A and the ground-pin
insertion hole 25B while suppressing scaling up of the plug
receptacle l, and also possible to suppress decrease in
strength of the plug-receiving portion 24.
(3) in this embodiment, the lower ends 25a of the
electrode-pin insertion holes 25A are located above the
center c1 in the up-down airection. Therefore, even if the
plug 2 is reversely inserted into the plug receptacle 1, the
electrode pins S1A are not inserted into the electrode-pin
insertion holes 25A. As a result, the reverse insertion can
be reliably prevented. Further, the minimum distance
between the electrode-pin insertion holes 25A and the
ground-pin insertion hole 25B can increase.
Furthermore, the ground-pin insertion hole 25B is
positioned corresponding to the center C1 in the up-down
direction, and the upper end 25b of the ground-pin insertion
hole 25B is located below the center C1 in the up-down
direction. Therefore, the minimum distance between the
electrode-pin insertion holes 25A and the ground-pin
insertion hole 25B can increase compared to a case that the
position of the ground-pin insertion hole is offset to the
right or Test side from the center C1 in the left-right
direction. Besides, the minimum distance between the
electrode-pin insertion holes 25A and the ground-pin
insertion hole 25B can increase compared to a case that the
upper end 25b of the ground-pin insertionvhole is positioned
above the center C1 in-the up-down direction.
(4) in tnis embodiment, the inclined sections 23a are
formed at corners of the insertion groove 23 and,
accordingly, the shape of the surrounding wall 54 is changed
in accordance with the shape of the insertion groove 23.
The shapes of the surrounding wall 54 and1 the insertion
groove 34 are changed depending on the kinds of supply
voltages, so that the insertion of the plug 2 into the plug
receptacle l which is used for a different supply voltage
can be prevented.
Moreover, the operator can visually recognize the
insertion orientation of the plug 2 into the plug receptacle
1 from the shape of the surrounding wall 54. Hence, the
operator can insert the plug 2 into the plug receptacle 1
while avoiding reverse insertion.
(5) In this embodiment, the inclined sections 23a are
formed at the lower portion of the insertion groove 23 (near
the side 24c of the plug-receiving portion 24) . Therefore,
a sufficient distance between the inclined sections 23a and
the pin insertion holes 25 can be obtained compared to a
case that che inclined sections are formed at the upper
portion of the insertion groove 23 (near the reference side
24b of the plug-receiving portion 24) . This can increase
strength of the plug-receiving portion 24 and suppress
breakage of the plug-receiving portion 24 which may be
caused by insertion and separation of the plug 2.
(6) In this embodiment, the portions of the plug-
receiving portion 24 corresponding to the inclined sections
23a of the insertion groove 23 are inclined.- Accordingly,
the width of the insertion groove 23 is not decreased.
if the portions of the plug-receiving portion 24 which
correspond to the inclined sections 23a of the insertion
groove 23 are not inclined, only the outer periphery of the
insertion groove 23 is inclined. Thus, .the width between
the outer periphery of the plug-receiving portion 24 and the
outer periphery of the insertion groove 23 is decreased at
the inclined sections 23a of the insertion groove 23.
However, in this embodiment, the plug-receiving portion 24
has the inclined sections corresponding to the inclined
sections 2 3a, so that the width of the insertion groove 23
is not decreased.
(7) in this embodiment, the inclined sections 23a of
the insertion groove 23 are formed in accordance with the
inclined shape of the plug-receiving portion 24. Therefore,
a structure for preventing insertion of the plug 2 into the
plug receptacle 1 for a different supply voltage can be
obtained simply by slantingly cutting the corner or corners
of the insertion groove 23 and the plug-receiving portion 24.
Hence, the plug receptacle 1 can be easily manufactured.
(8) in this embodiment, the front surface 22a of the
outlet unit 22 and the front surface 24a of the plug-
receiving portion 24 are located on the sama-'plane. Further,
the electrode pins 51A of the plug 2 is not extended beyond
the leading end of the surrounding wall 54 and the ground
pin 51B is extended, slightly beyond the leading end of the
surrounding wall 54. Due to this configuration, when the
plug 2 is reversely inserted into the outlet unit 22, the
ground pin 51B contact with the plug-receiving portion 24
before the surrounding wall 54 is inserted into the
insertion groove 23. Hence, an operator can recognize the
reverse insertion of the plug 2 into the outlet unit 22, and
the plug 2 is not connected to the outlet unit 22 in the
reverse insertion state. Accordingly, it is possible to
prevent the state in which the plug 2 is reversely inserted
into the outlet unit 22.
(9) "In this embodiment, the insertion groove 23 of the
outlet unit 22 is provided with the surrounding wall holding
portions 26 to be engaged with the engagement portions 55c
of the plug 2. For that reason, the surrounding wall 54 of
the plug 2 is supported by the insertion groove 23, and the
state in which the plug 2 is inserted into the plug
receptacle 1 can be maintained. As a consequence, the plug
2 can be prevented from being unintentionally •"separated from
the plug receptacle 1 by pulling the cable portion 2A.
(10) in this embodiment, the surrounding wall holding
portions 26 are disposed at both the left and the right
sides of the two electrode-pin insertion holes 2SA, so that
the surrounding wall 54 can be stably held by the insertion
groove 23 compared to a case that the engagement portion is
formed at one side of the electrode-pin insertion holes 25A.
As a result, the state in which the plug 2 is inserted into
the plug receptacle 1 can be stably maintained,,-
(11) In this embodiment, the second, inclined sections
55c2 of the engagement portions 55c of the plug 2 are
inclined so as to be gradually widened toward the front side.
Therefore, when the second inclined sections 55c2 contact
with the outer wall 23c of the insertion groove 23 by the
insertion of the plug 2 into the outlet unit 22, the second
inclined sections 55c2 are gradually elastically deformed
inwardly by reaction force of the contact between the second
inclined sections 55c2 and the outer wall 23c. As a result,
the engagement portions 55c can be engaged with the
surrounding wall holding portions 26 without an operator's
operation of gripping the locking units -55, which is
convenient in use.
(12) In this embodiment, the locking uri'its 55 and the
surrounding wall 54 are formed as a unit. Therefore, the
number of components constituting the plug 2 can be reduced
compared to a case that the locking units 55 and the
surrounding wall 54 are formed separately.
(13) in this embodiment, the outlet units 22 are
arranged in the up-down direction, and the electrode-pin
insertion holes 25A are arranged in the left'-right direction.
Further, the surrounding wall holding,. portions 26 are
arranged in the left-right direction, so that the locking
units 55 of the plug 2 are arranged in , the left-right
direction. Accordingly, when the plugs 2 are inserted into
the outlet units 22 adjacent to each other in the up-down
direction, the locking units 55 of the plugs 2 can be
prevented from being adjacent to each other. This can
suppress scaling up of the plug receptacle 1 in the up-down
direction. Moreover, an operator does not need to insert
the fingers between the plugs 2 adjacent to each other in
the up-down direction, so that it is convenient to insert a
plurality of plugs 2 into the plug receptacle 1.
(14) In this embodiment, the outlet units 22 are
arranged in the up-down direction; the left or right
electrode-pin insertion holes 25A of the outlet units 22 are
positioned corresponding to each other in the up-down
direction; and the ground-pin insertion holes 25B of the
outlet units 22 are located corresponding to each other in
the up-down direction. Hence, the pin-receiving pieces 13
respectively corresponding to the electrode-pin insertion
holes 25A and the ground-pin insertion hole 25B are located
corresponding to each other in the up-down direction, which
enables the pin-receiving piece connection portion 12 for
connecting the pin-receiving pieces 13 to have a flat plate
shape extending in the up-down direction. In other words,
the shape of the pin-receiving piece connecfri-on portion 12
can be simplified. As a result, scaling up of the plug
receptacle 1 in the left-right direction can b"e suppressed.
(Second Embodiment)
A second embodiment in which a plug receptacle of the
present invention is embodied as a table tap connected to a
DC outlet buried in a wall of a building will be described
with reference to Figs. 12 to 15. Fig. 15 omits
illustration of the cable and the plug.
The entire DC power distribution system 70 installed
at a house H will be described with reference to Fig. 12.
As shown in Fig. 12, the house H is provided with a DC
power supply unit 71 for outputting a DC power; and an
electric device 72 operating at a DC power. The DC power is
supplied to the electric device 72 through DC power supply
lines wdc connected to an output terminal of the DC power
supply unit 71.
Moreover, DC breakers 73 are provided between the DC
power" supply unit 71 and the electric device 72. The DC
breakers 73 monitor a current flowing in the DC power supply
lines Wdc and restrict or interrupt, when an error is
detected, DC power supply from the DC power supply unit 71
to the electric device 72 through the DC -power supply lines
Wdc.
The DC power supply unit 71 basically generates a DC
power by converting an AC power supplied from the outside of
the house H. To be specific, the AC power from the AC power
supply AC passes through a master breaker 75 installed in a
power distributor 74. Then, the AC power is input to an
AC/DC converter 16 including a switching power supply and is
converted into DC power. The DC power output from the AC/DC
converter 54 passes through a control unit 77 and then is
input to the DC breakers 73. Moreover, the DC. breakers 73
are connected to respective DC outlets 80- through the power
supply lines Wdc.
The DC power supply unit 71 has a"*- secondary battery
7 8a used for a time during which power is not supplied from
the AC power supply (e.g., power supply failure period of
the AC power supply or the like), a solar battery 56 for
generating a DC power and a fuel battery 78c. The AC/DC
converter 76 for generating a DC power from an AC power
serves as a main power supply 79, whereas the solar battery
78a, the secondary battery 78b and the fuel cell 78c serve
as a decentralized power source 78.
The control unit 77 controls distribution of the DC
power from the main power supply 79 and the DC power from
the decentralized power source 78. The control unit 77 has
an AC/DC converter 77a for converting DC voltages of the DC
power from the main power supply 79 and the decentralized
power source 78 into required voltages. The DC power from
the main power supply 79 and the decentralized power source
78 are distributed as required and supplied to the electric
devices 77 via the DC outlets 80.
Here, the DC outlet 80 is connected to a plug 3C of a
table tap 3 (hereinafter, referred to as a "tap 3"). By
connecting a plug 72a of an electric device 72 to the outlet
unit 22 of the plug receptacle 1, DC powers from the DC power
supply unit 71 is supplied to the electric device 72.
Hereinafter, a configuration of the tap 3 will be
described with reference to Fig. 13. The' tap 3 of this
embodiment is different from the plug receptacle 1 of the
first embodiment in that the number and the shape of the
outlet units 22 are changed and the plug 3C is provided at
the cable 3B. In the following description, the differences
between the tap 3 and the plug receptacle 1 will be descried.
Moreover, like reference numerals will be used for like
parts as those of the first embodiment, and redundant
description thereof will be omitted.
As illustrated in Fig. 13, the tap 3 include: a
housing 3A; a power supply member (not shown), accommodated
in the housing 3A; a cable 3B connected to the power supply
member and extending from the housing 3A to the outside; and
a plug 3C provided at the other end portion^ of the cable 3B
opposite to the end portion connected to the, power supply
member. The housing 3A io provided with four outlet units
22 spaced from each other in the up-down direction. Further,
the configurations of the power supply member and the plug
3C are substantially the same as those of the power supply
member IB and the plug 2 of the first embodiment.
Next, the shape of the outlet unit 22 in accordance
with the kinds of power supply circuits (hot shown) as power
supply sources will be described with reference to Fig. 14.
The power supply circuits are provided between the DC power
supply unit 71 and the DC outlet 80, e.g., inside the power
distributor 74.
The power supply circuits include at" least an Et.V
(extra-low voltage) circuit and an SELV (safety extra-low
voltage) circuit. The ELV circuit and the SELV circuit are
standardized by ICE 60950-1 and IEC 60335-r. "'
The electric device 72 (see Fig. 12) has different
internal insulation structures depending on whether the
power supply circuit is an ELV circuit or an SELV circuit.
in other words, the electric device 72 -for ELV employs a
double insulation structure or a reinforced insulation
structure. On the other hand, the electric device 72 for
SELV may not employ a double insulation structure or a
reinforced insulation structure and thus has a simpler
insulation structure than that of the electric device 72 for
ELV.
When the electric device 72 for ELV is connected to
the tap 3 for SELV, problems are not generated due to the
complicated insulation structure of the electric device 72.
on the other hand, when the electric device for SELV is
connected to the tap 3 for ELV, a problem in which the
electric device 72 hao a breakdown when a hazardous voltage
is supplied thereto may be generated due to the simple
insulation structure of the electric device 72. Therefore,
the tap 3 and the plug 72a should be identified depending on
whether they are suitable for ELV or SELV. Especially, the
erroneous connection of the electric device'72 for SELV with
the tap 3 for ELV should be prevented.
For that reason, in the outlet unit 22 for SELV, an
extended groove 23b is formed at a lower left corner of the
insertion groove 23, as illustrated in Fig. 14. The
extended groove 23b is continuously extended upward from the
lower sids of the insertion groove 23. On' the contrary, the
outlet unit 22 for ELV is not provided with the extended
groove 23b (see Fig. 13). In this manner, the'outlet unit
22 for SELV and the outlet unit 22 for ELV can be identified.
Hence, the plug 72a for ELV can be inserted into the
outlet unit 22 for SELV, whereas the plug 72a for SELV
cannot be inserted into the outlet unit 22 for ELV. As a
consequence, the connection between the tap 3 for ELV and
the electric device 72 for SELV can be prevented.
Further, the outlet unit can have another
configuration in accordance with the kinds of power supply
circuits, such as a configuration shown in Fig. 20A (first
configuration) in which the extended groove 23b is formed
separately from the insertion groove 23, or a configuration
shown in Pig. 20B (second configuration) in which the
extended groove 23b is formed outside the insertion groove
23, i.e., outside the plug-receiving portion 24.
However, the first configuration is disadvantageous in
that the strength of the plug-receiving portion 24 decreases
due to decrease in the distance between the extended groove
23b and the pin insertion holes 25. In the second
configuration, although the strength of the plug-receiving
portion 24 does not decrease, the outlets-unit 22 is scaled
up due to the space required for the extended groove 23b.
In this embodiment, the extended -groove 23b is
continuously extended from the insertion groove 23 at the
lower portion of the insertion groove 23, so that the
distance between the pin insertion holes 25 and the extended
groove 23b ie longer that that in the first-configuration.
Moreover, the extended groove 23b extends upward from the
insertion groove 23 in the plug-receiving portion 24.
Accordingly, the scaling up of the outlet unit 22 can be
suppressed. That is, this embodiment can solve the problems
of the first and the second configuration.
As shown in Fig. 15, the combination of the outlet
units 22 of the tap 3 may include the outlet units 22 having
a configuration for identifying the kinds of"supply voltages
and the outlet units 22 having a configuration for
identifying the kinds of power supply circuits such as an
SELV circuit and an ELV circuit. The combination of the
outlet units 22 can be variously modified without being
limited to that of Fig. IS.
This embodiment can provide the following effects in
addition to the effects (1) to (14} of the first embodiment.
(15) In this embodiment, the extended groove 23b
extends from the insertion groove 23, so that the scaling up
of the outlet unit 22 or the decrease in strength of the
plug-receiving portion 24 can be suppressed compared to a
case that the extended groove 23b is formed separately from
the insertion groove 23.
(16) In this embodiment, the extend groove 23b is
formed at the lower side of the insertion groove 23 and,
thus, the strength of the plug-receiving portion 24 can be
improved - compared to a case that the extended groove is
formed between the pin insertion holes 25 and the insertion
groove 23. This can suppress the breakage of the plug-
receiving portion 24 which may be caused by insertion and
separation of the plug 72a.
The plug receptacle 1 and the tap 3 can be variously
modified without being limited to those of the
aforementioned embodiments. The following modifications can
be applied not only to the aforementioned embodiments but to
an embodiment haying combination of different modifications.
In the aforementioned embodiments, the supply voltages
of the plug receptacle 1 and the tap 3 are identified by the
inclined sections 23a of the insertion groove 23. However,
the configuration for identifying the supply voltages of the
plug receptacle l and the tap 3 is not limited thereto. The
shape of the insertion groove 23 of the plug receptacle 1
and the tap 3 can be changed such that only the plug 2 and
the surrounding wall 54 of the plug 72a for the same supply
voltage as that of the plug receptacle 1 and, the tap 3 can
be inserted thereinto. For example, a stepped recess 23e
can be formed by cutting one of four corners of the
insertion groove 23, as shown in Fig. 16A. Besides, a
protrusion 23f protruding outward can be formed after
cutting a part of the insertion groove 23, as depicted in
Fig. 16B. The shapes of the surrounding wall 54 of the plug
2 and the plug 72a viewed from the rear side are determined
in accordance with the shape of the insertion groove 23.
Although the inclined sections 23a are formed at the
lower side of the insertion groove 23 in the above-described
embodiments, the inclined sections 23a can be formed at the
upper side of the insertion groove 23
Besides, in the above-described embodiments, the lower
portions 25a of the pin insertion holes 25 are positioned
upper than the center C1 of the plug-receiving portion 24.
However, the positions of the lower portions 25a are not
limited thereto, and can be changed as long as it is
possible to prevent the insertion of the plug pins 51 into
the pin insertion holes 52 when the plug 2 "and the plug 72a
are reversely inserted into the plug receptacle 1 and the
tap 3. The lower portions 25a can be positioned at
substantially the same horizontal level as the center C1.
Although the insertion groove 23 and the plug-
receiving portion 24 are formed in a rectangular shape in
the aforementioned embodiments, the insertion groove 23 and
the plug-receiving portion 24 may be formed in a square
shape.
Further, in the aforementioned embodiments, the
around-pin insertion hole 25B of the outlet unit 22 is
positioned at the same horizontal level as the center C1 of
the plug-receiving portion 24 and vertically lower than the
electrode-pin insertion holes 25A. However, the position of
the ground-pin insertion hole 25B is not limited thereto.
For example, the ground-pin insertion hole 25B can be
deviated rightward or leftward from the center Cl. Or, the
ground-pin insertion hole 25B and the electrode-pin
insertion holes 25A can be positioned at the substantially
same height levsl.
In the second embodiment, the pin insertion holes 25
of the outlet unit 22 include the electrode-pin insertion
holes 25A and the ground-pin insertion hole 25B. However,
the configuration of the pin insertion holes 25 is not
limited thereto. For example, the pin insertion holes 25
may include only the electrode-pin insertion holes 25A
without the ground-pin insertion hole 25B, as can be seen
from Fig. 17 .
In the second embodiment, the extended portion 23b is
formed at the lower left corner of the insertion groove 23.
However, the position of the extended portion 23b is not
limited thereto. For example, the extended groove 23b may
be formed at the lower right corner of the insertion groove.
The extended groove 23b is not necessarily formed at
the lower side of the insertion groove 23, and may be formed
at any one of four sides of the insertion groove 23.
Moreover, the extended portion 23b is not necessarily
provided at the plug-receiving portion 24 For example, the
extended portion 23b may be provided at the front surface
22a of the outlet unit 22.
In the second embodiment, the extended groove 23b is
formed at the lower left corner of the insertion groove 23.
However, the position of the extended groove 23b is not
limited thereto. For example, in the configuration shown in
• Fig. 17 in which the pin insertion holes 25 do not include
the ground-pin insertion hole 25B, the extended groove 23b
can be formed at a lower central portion of the insertion
groove 23, In this configuration, the extended groove 23b
can be formed at the lower central portion of the insertion
groove 23 regardless of types of supply voltages.
In the above embodiments, the shape of the insertion
groove 23 of the outlet unit 22 is changed depending on the
kinds of supply voltages and/or the kinds of power supply
circuits. However, the shape of the insertion groove 23 of
the outlet unit 22 may be partially changed depending on the
kinds of supply currents, as illustrated in Figs. 18A to 18C.
Pigs 18A to 18C show the outlet unit for SELV and 48V
as an example.
The electrical devices require a plurality of supply
currents, e.g., 6A, 12A and 16A. In this embodiment, in
order to identify the outlet unit 22 in accordance with the
types of supply currents, the shape of the insertion groove
23 viewed from the front side is changed by forming an
extended groove 23a' at the insertion groove 23. To be
specific', in case of the supply current of 6A, an extended
groove is not formed as shown in Fig. 18A.
In case of the supply current of 12"A", an extended
groove 23a' having a triangular cross section extends inward
in the left-right direction (Y direction) at an upper
portion of the right inclined section 23a, as illustrated in
Fig. 18B. In case of the supply current of 16A, the
extended portions 23a' are formed at both of the inclined
sections 23a, as shown in Fig. 18C. When the inclined
sections 23 are not formed at the insertion groove 23, the
extended groove 23a' has a quadrangular cross section viewed
from the front side.
The outlet unit can be identified in accordance with
the kinds of power supply circuits such as an SELV circuit
and an ELV circuit in addition to the kinds of supply
currents and supply voltages. To do so, the extended
portion 23b can be formed at the outlet unit 22 for SELV, as
shown in Figs. ISA to 18C.
Various examples of changing the shape of the .
insertion groove 23 of the outlet unit 22 in accordance with
the kinds of supply voltages, supply currents or power
supply circuits are described in PCT; -Application No.
PCT/IB20l0/001892 filed by the present Applicant, the
contents of which are incorporated herein by reference.
In the aforementioned embodiments, the surrounding
wall holding portions 26 to be engaged with the locking
units 55 are formed at both of the left and the right sides
of the insertion groove 23. However, the positions of the
surrounding wall insertion portions 26 are not limited
thereto. For example, the surrounding wall holding portions
26 may be formed at both of the upper and'-lower sides of the
insertion groove 23. In that case, the same effect (9) of
the first embodiment can be obtained.
While the invention has been shown arid 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.
We Claim:
1. A plug receptacle comprising a housing having at least
one outlet unit to which a plug is adapted to be connected
to supply a DC power to the plug, the plug including a
plurality of plug pins having a circular bar shape; and a
substantially quadrangular-shaped surrounding wall for
surrounding the plug pins; and a cable, connected to the
housing, for supplying the DC power to the housing, wherein:
the outlet unit includes a plug-receiving portion
having a plurality of substantially circular pin-inserting
holes into which the plug pins of the plug are inserted, the
plug-receiving portion having a substantially quadrangular
shape viewed from a front side thereof; and an insertion
groove formed to surround a periphery of the plug-receiving
portion, the insertion groove being adapted to receive the
surrounding wall of the plug and having a- substantially
quadrangular shape viewed from the front side; and
the pin-receiving holes are arranged along one side of
the plug-receiving portion serving as a reference side and
offset closer to the reference side than an opposite side to
the reference side.
2. The plug receptacle of claim 1, wherein a shape of at
least one of the plug-receiving portion and "the insertion
groove, viewed from the front thereof, is partially changed
depending on the kinds of a supply voltage or a supply
current.
3. The plug receptacle of claim 2, wherein the shape of
the insertion groove viewed from the front is changed such
that an area of the plug-receiving portion is decreased as
compared with a case that the plug-receiving portion has the
substantially quadrangular shape viewed from the front.
4. The plug receptacle of claim 3 , wherein the shape of
the insertion groove viewed from the front is changed
differently depending on the kinds of the supply voltage or
the supply current by cutting at least one corner of the
substantially quadrangular shape of the plug-receiving
portion depending on the kinds of the supply voltage or the
supply current, and forming the insertion groove along an
outer periphery of the plug-receiving portion.
5. The plug receptacle of claim 2, wherein a portion of
the insertion groove whose shape is changed depending on the
Kinds of the supply voltage or the supply current is closer
to the opposite side to the reference side than the
reference side.
6. The plug receptacle of claim 2, wherein the shape of
the insertion groove viewed from the front is changed such
that an area of the plug-receiving portion is increased as
compared with a case that the plug-receiving portion has the
substantially quadrangular shape viewed from the front.
7. The plug receptacle of claim 2 or 4, wherein the shape
of the insertion groove viewed from the front is partially
changed by forming an extension groove extending from the
insertion groove.
8. The plug receptacle of claim 7, wherein the extension
groove is formed by extending a part of the insertion groove
into the plug-receiving portion.
9. The plug receptacle of claim 7, wherein the extension
groove is provided closer to the opposite side to the
reference side of the plug-receiving portion than the
reference side.
10. The Plug receptacle of claim 7, wherein the extension
qroove is formed on the front surface of the outlet main
body by outwardly extending a part of the insertion groove.
11. The plug receptacle of claim 1, wherein a shape of at
least one of the plug-receiving portion and the insertion
groove, viewed from the front thereof, is partially changed
depending on the kinds of a power supply circuit serving as
a power supply source.
12. The plug receptacle of claim 11, wherein the shape of
the insertion groove viewed from the front is changed such
that an area of the plug-receiving portion is decreased as
compared with a case that the plug-receiving portion has the
substantially quadrangular shape viewed from the front.
13. The plug receptacle of claim 12, wherein the shape of
the insertion groove viewed from the front is changed
differently depending on the kinds of the power supply
circuit by cutting at least one corner of the substantially
quadrangular shape of the plug-receiving portion depending
on the kinds of the power supply circuit, viewed from the
front, and forming the insertion groove along an outer
periphery of the plug-receiving portion.
14. The plug receptacle of claim 11, wherein a portion of
the insertion groove whose shape is changed depending on the
kinds of the power supply circuit is closer to the opposite
side to the reference side than the reference side.
15. The plug receptacle of claim 11, wherein the shape of
the insertion groove viewed from the front is changed such
that an area of the plug-receiving portion is increased as
compared with a case that the plug-receiving portion has the
substantially quadrangular shape viewed from the front.
16. The plug receptacle of claim 11 or 13, wherein the
shape of the insertion groove viewed from the front is
partially changed by forming an extension groove extending
from the insertion groove.
17. The plug receptacle of claim 16, wherein the extension
groove is formed by extending a part of the insertion groove
into the plug-receiving portion.
18. The plug receptacle of claim 16, wherein the extension
groove is provided closer to the opposite side to the
reference side of the plug-receiving portion than the
reference side.
19. The plug receptacle of claim 16, wherein the extension
groove is formed on the front surface of the outlet main
body by outwardly extending the insertion groove.
20. The plug receptacle of claim 11, wherein the shape of
the insertion groove viewed from the front is partially
changed only when the power supply circuit is a safety extra
low voltage (SELV) circuit.
21. The plug receptacle of claim 1, wherein the plug pins
of the plug include a ground pin, and the pin-inserting
holes of the plug-receiving portion include a ground pin
inserting hole into which the ground pin Of the plug is
inserted.
22. The plug receptacle of claim 21, wherein the ground
pin inserting hole is provided offset closer to the opposite
side to the reference side.

Abstract:

A plug receptacle includes a housing having al least one
outlet unit to which a plug is adapted to be connected to supply a DC power
to the plug, and a cable, connected to the housing, for supplying the DC
power to the housing. The outlet unit includes a plug- receiving portion
having a plurality of substantially circular pin- inserting holes into which
plug pins of the plug are inserted and an insertion groove formed to surround
a periphery of the plug-receiving portion. The plug- receiving portion
has a substantially quadrangular shape viewed from a front side thereof
The insertion groove is adapted to receive a surrounding wall of the
plug and has a substantially quadrangular shape viewed from the front
side. The pin-receiving holes are arranged along one side of the plug- receiving
portion serving as a reference side and offset closer to the reference
side than an opposite side to the reference side.