Note: Descriptions are shown in the official language in which they were submitted.
B OUND OF THE INVENTION
This invention relates to interlocking mechanisms for
switched socket outlets.
In a known interlocked switched socket outlet, a plug
inserted therein is secured against withdrawal by direct pull
from the socket by a bayonet-type fixing, the operation of which
simply requires the plug to be given a small twist after inser-
tion. The socket is surrounded by a ring which is moved axially
against the action of springs by insertion of the plug through
engagement with a skirt projecting therefrom, The ring is
capable of rotation between a plug-accepting position, in which
a key projecting inwardly from the ring is receivable within a
corresponding cut-out on the skirt when the plug is aligned for
insertion, and a plug-inserted position into which the ring is
rotated by the twisting movement required to secure the plug in
the socket, Rotation between these two positions is limited by
two pins, each having a flat, circular head and each projecting
through a respective diametrically opposite arcute slot formed
in a flange projecting from the ring, Each flange is recessed
2~ at one end of the slot to receive a pillar head when the ring
is in the accepting position; as the ring is resiliently urged
against the heads by the above-mentioned springs, it is locked
against rotational movement in either direction,
The ring is also formed with a cam projecting into a
recess at one end of a slide bar located tangentially of the
ring and arranged so that rotation of the ring caused by twisting
the plug causes longitudinal displacement of the slide bar in a
corresponding sense. The bar is apertured at the other end to
receive the free end of an operating rod, the other end of which
is pivotally connected to a crank on a switch spindle, such that
operation of the switch from the "off" to the "on" position
causes the rod to move axially and
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1 project further through the aperture, the pivotal connection
allowing the free end of the rod to move with the bar. A stop
screw passes through the housing in a position which is opposite
the end of the rod when the ring is in the plug-accepting position.
I-~en the socket is out of use, the ring is in the
plug-accepting position and the switch is in the "off" position.
Any inadvertent attempt to move the switch to the "on" position
is prevented by abutment of the end of the rod against the stop
screw. Insertion of the plug into the socket initially causes
engagement of the key on the ring into the recess on the plug
skirt, and continued insertion causes the ring to be moved axially
against the action of the springs t~ disen~age the pillar heads
from the recesses and allow rotation of the ring with the skirt
o~ the plug when the latter is twisted to lock the plug into
position. By this rotation of the ring, the slidebar is moved
away from the stop screw to a position which allows the operating
rod to move sufficiently for the switch to be moved to the "on"
position. If an attempt is made to remove the plug while the
switch is in the "on" position, the necessary movement of the
slide bar is prevented by the abutment of the end of the rod
against the side of the set screw.
The above-described construction is, however, dependent
on the rotation of the plug in the socket outlet.
SUr~MARY OF T~E INVENTION
According to the present invention, there is provided
an interlock mechanism for a switched socket outlet having a switch
and a socket for accepting a plug having an external key, the
mechanism comprising an interlock member which is mounted for
sliding movement between a switch-open position and a switch-closed
position, an eccentric cam member rotatable by operation of the
switch for imparting said movement to the interlock member and a
1 pin which is displaceable against the action of resilient means
by the key upon insertion of the plug, the arrangement being such
that in the switch-open position the interlock member allows in-
sertion of the plug to cause depression of the pin from a normal
position, in which the pin prevents attempted closure of the switch
by obstructing displacement of the interlock member to the switch-
closed position, to a retracted position in which the pin allows
such movement of the interlock member. The interlock member may
be so arranged as, when in the switch-closed position, to obstruct
the return path of the key to prevent attempted withdrawal of the
plug from the socket when the latter is live. Preferably, the
interlock member is also so arranged that the key prevents its
being displaced from the switch-open position until the plug is
fully inserted. Preferably the switch is a/rotary switch, that is
a switch actuated by the rotation of a spindle or shaft.
The mechanism according to the invention is particula~ly
suitable for a side-by-side arrangement of the socket and switch
which allows the interlock member to be arranged for sliding move-
ment imparted by an eccentric on the switch spindle. However,
where the socket and switch have other relative dispositions, it
may be necessary to employ some form of linkage between the inter-
lock member and the switch in order to impart the necessary
movement to the interlock member.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the invention will now be described,
by way of example, with reference to the accompanying drawings in
which:
Figure 1 is a side elevation, partly in section, showing
a switched'socket outlet incorporating an interlocking mechanism
according to the invention, with the plug withdrawn;
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1 Figure 2 is an elevation similar to that of Figure 1
showing the socket with the plug inserted;-and
Figure 3 is a horizontal section through the socket
outlet of Figure 1 viewed from beneath.
DETAILED DESCRIPTION
As best shown in Figure 1, the interlocked switched
socket outlet 10 of this invention is housed in a box 11 to which
a cover 12 is secured at each corner by a screw 13, The outlet
is typically rated at 15 amperes and 250 volts. A socket 14
having a basal flange 15 is supported from the cover 12 by posts
16 to which the flange 15 is screwed; access to the socket 14 is
through a circular aperture provided with a small-keyway 17 and
closable by a spring cover 18. A plunger 19 is arranged for
reciprocal movement within corresponding apertures through the
flange 15 and a plate 20, the lower portion 21 passing through
the plate 20 being of reduced thickness and~surrounded by a spring
22 which urges the plunger 19 upwardly, Also depending from
cover 12 is a switch 23 having a spindle 24 on which is mounted
a knob 25 and an eccentric 26.
As shown in Figure 2, a plug 27, having a depending
skirt 28 from which projects a key 29 having a distal end face 30
and a proximal end face 31, may be inserted into the socket 15.
As may best be seen from Figure 3, a slide plate 32
embracing the socket 15 is slidable mounted on the underside of
the cover 12, movement being imparted by the camming action of
the eccentric 26 against the wall of an orifice 33. The slide
plate 32 is formed with two depending support plates 34 and 35
between which extends a web constituting detent plate 36. That
portion of the slide plate 32 bounded hy the plates 34 and 35, and
the plate 36 constitutes a catch 37.
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1 With the switch 23 in the "off" position, the passage
of the key 29 through the keyway 17 i~ unobstructed and the plug
27 may ~e inserted until the leading end face 30 of the key 29
has engaged the end face of the plunger 19 and depressed it
against the action of the spring 22. In the fully inserted
position of the plug 27, the switch 23 may be closed because the
associated movement of the eccentric 26 causes sliding movement
of the slide plate 32 to the right as seen in the Figures. This
sliding movement is impeded neither by the plunger 19, which is
held depressed by the key 29, or by the key 29 itself~ as its
upper face 31 is cleared by the catch 37. Clearly, the plug
cannot be withdrawn until the switch 23 is in the "off" position
and the slide plate in the position shown in Figures 1 and 3.
Operation of the switch 23 with the plug 27 withdrawn
is prevented by abutment of the 32 against the projecting plunger
19; and operation of the switch 23 before full insertion of the
plug 27 is additionally prevented by abutment of the catch 37
against the key 29,
Although the mechanism has been described with reference
to a relatîvely small socket outlet, it can be adapted for use
with much larger outlets and with any outlets for use with plugs
having similar locking key features,
While one advantageous embodiment has been chosen to
illustrate the invention~ it will be understood by those skilled
in the art that various changes and modifications can be made
therein without departing from the scope of the invention as
defined in the appended claims,
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