Note: Descriptions are shown in the official language in which they were submitted.
TAMPER-RESISTANT ASSEMBLY
WITH WEAR-RESISTANT SHUTTERS
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of provisional application
No. 61/871,723, filed August 29, 20131
FIELD OF THE INVENTION
[0002] The present invention relates generally to a shutter member
of a tamper-resistant assembly of an electrical wiring device. More
particularly, the present invention relates to a cover member for a shutter
member of an electrical wiring device. Still more particularly, the present
invention relates to a shutter member having pockets to receive tabs of a
cover member to secure the cover member to the shutter member.
BACKGROUND OF THE INVENTION
[0003] Shutter assemblies are disposed in electrical wiring devices
to
prevent accidental insertion of an object into an electrically energized
portion of the electrical wiring device. A ramped surface of a first shutter
member overlies a blocking portion of a second shutter member. An
inserted object contacts the ramped surface of the first shutter member,
thereby sliding the first shutter member out of the way. The inserted
object is prevented from accessing the energized contact by the blocking
portion of the second shutter member. Accordingly, two objects must be
inserted to defeat the shutter members of the shutter assembly to access
the electrical contacts.
[0004] Inserting two objects, such as the blades of a plug, contacts
the two ramped surfaces of the two shutter members, thereby causing
both shutter members to slide. The two blades of the inserted plug then
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can engage the electrical contacts disposed behind the shutter assembly.
After repeated plug insertions, the ramped surfaces of the shutter
members, which are usually molded of plastic, can become gouged or
otherwise marred. Such damage can cause the shutter members to fail to
operate upon insertion of a plug, such that the plug cannot be electrically
connected to the electrical contacts of the electrical wiring device.
[0005] While protective shutter covers are known in the prior art,
they typically are complex and complicate assembly of the device in which
they are installed. Accordingly, a need exists for a simple, easy-to-install
cover member for protecting the shutters of a tamper-resistant assembly
of an electrical wiring device.
SUMMARY OF THE INVENTION
[0006] A tamper-resistant assembly for an electrical device according
to the invention includes a housing, at least one shutter member having a
ramped surface and movably mounted in a housing, and a cover member
connected to the shutter member and overlying and protecting the
ramped surface from an object inserted in an opening in the electrical
device. The shutter member has a pair of pockets on opposite sides of the
ramped surface. The cover member has a central portion and a pair of
laterally extending wings on opposite sides of the central portion anchored
in the pockets.
[0007] The pockets in the shutter member preferably extend laterally
outward from the sides of the ramped surface. The wings of the cover
member preferably are configured such that they flex inward during
assembly and then snap into the pockets. Other mating features of the
cover member and the shutter member help ensure that the cover
member remains securely anchored during use of the electrical device.
[0008] The invention also is directed to a tamper-resistant electrical
receptacle that incorporates the aforementioned tamper-resistant
assembly. The assembly preferably has a pair of shutter members that
move in opposite directions, and each shutter member has a cover
member as described above.
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[0008A] In a broad aspect, the present invention pertains to a tamper-
resistant assembly for
an electrical device comprising a housing, and at least one shutter member
movably mounted in
the housing, the shutter member having a ramped surface and a pair of pockets
on opposite sides
of the ramped surface, each pocket having a respective side surface and end
surface. There is a
cover member connected to the at least one shutter member and overlying and
protecting the
ramped surface from an object inserted in an opening in the electrical device.
The cover member
has a central portion and a pair of laterally extending wings on opposite
sides of the central
portion forming an obtuse angle with the central portion, each of the wings
conforming to the
respective side surface of the pockets, and anchored in a respective one of
the pockets.
[0008B] In a further aspect, the present invention provides a tamper-
resistant electrical
receptacle comprising a housing, and a pair of electrical contacts in the
housing, and a pair of
external opening in the housing, the contacts being accessible through
respective ones of the
openings by respective blades of an inserted electrical plug. A pair of
shutter members is
movably mounted in the housing between respective ones of the contacts and
respective ones of
the openings, each shutter member having a ramped surface and a pair of
pockets on opposite
sides of the ramped surface, each pocket having a respective side surface and
end surface. There
is provided a pair of cover members, each cover member connected to a
respective one of the
shutter members and overlying and protecting the ramped surface from a plug
blade inserted in
the opening. Each of the cover members has a central portion and a pair of
laterally extending
wings on opposite sides of the central portion forming an obtuse angle with
the central portion.
Each of the wings conform to the respective side surface of the pockets, and
is anchored in a
respective one of the pockets.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0009] A preferred embodiment of the disclosed invention is
described in detail below purely as an example, with reference to the
accompanying drawing, in which:
[0010] FIG. 1 is a perspective view of an electrical wiring device with
a cover removed and receiving a tamper-resistant assembly in accordance
with an exemplary embodiment of the present invention;
[0011] FIG. 2 is another perspective view of the electrical wiring
device of FIG. 1;
[0012] FIG. 3 is a perspective view of the tamper-resistant assembly
of FIG. 1;
[0013] FIG. 4 is a side elevational view of the electrical wiring device
of FIG. 1 prior to insertion of an electrical plug therein;
[0014] FIG. 5 is an end elevational view in cross section taken along
line 5-5 of FIG. 4;
[0015] FIG. 6 is an end elevational view in cross section taken along
line 6-6 of FIG. 4;
[0016] FIG. 7 is a side elevational view of the electrical wiring device
of FIG. 1 after insertion of an electrical plug therein;
[0017] FIG. 8 is an end elevational view in cross section taken along
line 8-8 of FIG. 7;
[0018] FIG. 9 is an end elevational view in cross section taken along
line 9-9 of FIG. 7;
[0019] FIG. 10 is an exploded perspective view of a first shutter
member and a cover member of FIG. 1;
[0020] FIG. 11 is a perspective view of the cover member connected
to the first shutter member of FIG. 10;
[0021] FIG. 12 is a lower perspective view of the cover member
connected to the first shutter member of FIG. 10;
[0022] FIG. 13 is another lower perspective view of the cover member
connected to the first shutter member of FIG. 10;
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[0023] FIG. 14 is an exploded perspective view of a second shutter
member and a cover member of FIG. 1;
[0024] FIG. 15 is perspective view of the cover member connected to
the second shutter member of FIG. 4;
[0025] FIG. 16 is a lower perspective view of the cover member
connected to the second shutter member of FIG. 14; and
[0026] FIG. 17 is another lower perspective view of the cover member
connected to the second shutter member of FIG. 14.
[0027] Throughout the drawings, like reference numerals will be
understood to refer to like parts, components and structures.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT
[0028] As used in this application, the terms "front," "rear," "upper,"
"lower," "upwardly," "downwardly," and other orientative descriptors are
intended to facilitate the description of the exemplary embodiments of the
present invention, and are not intended to limit the structure thereof to
any particular position or orientation.
[0029] The present invention generally relates to a cover member 11
securable to a shutter member of a tamper-resistant assembly 55 of an
electrical wiring device 56, as shown in FIGS. 1-17. First and second
shutter members 12 and 41 in accordance with an exemplary
embodiment of the present invention, as shown FIGS. 1-4, can be used
with any suitable electrical wiring device, such as a combination 15 and
20 amp electrical receptacle 56 as shown in FIGS. 1, 2 and 4-9. The
tamper-resistant assembly 55 provides tamper resistance for the electrical
wiring device 56 adapted to receive both 15 and 20 amp plugs 57 and 58,
as shown in FIGS. 4 and 7.
[0030] The tamper-resistant assembly 55, as shown in FIG. 3,
includes a base member 59, the first shutter member 12, the second
shutter member 41 and a spring 60. The first shutter member 51 is
slidably connected to the base member 41.
[0031] The electrical receptacle 56 has a front cover 61 connected to
a back housing 62 with a ground strap 63 connected thereto, as shown in
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FIG. 1. The ground strap 63 has openings 64 disposed at opposite ends
adapted to receive fasteners 65 to connect the electrical receptacle 56 to
an electrical box (not shown). The ground strap 63 may extend around a
rear surface of the back housing or may, alternatively, be disposed
between the front cover and the back housing. A plurality of arms 66
extend forwardly from the back housing 62 and are received by
receptacles 67 of the front cover 61 to connect the front cover to the back
housing. Conductive elements are disposed within the back housing 62
to receive and make electrical contact with inserted blades of an electrical
plug, as shown in FIGS. 8 and 9.
[0032] The front cover 61 has openings suitably disposed to receive
the prongs and blades of a conventional male plug. The electrical
receptacle 56 shown in FIGS. 1 and 2 is a duplex electrical receptacle,
although the present invention is not limited thereto. A first opening 68
and a second opening 69 are disposed in the front cover 61 to receive the
blades that form part of the power circuit for the appliance being
connected thereto. A third opening 70 receives the ground prong of a
grounded three-prong connector. The first opening 68 is substantially
rectangular in shape and the second opening 69 is substantially T-
shaped. The second opening 69 may receive a plug blade that is either
substantially parallel to the blade passing through the first opening 68 as
shown in FIG. 9, or that is substantially perpendicular to the blade
passing through the first opening 68 as shown in FIG. 8. The second
opening 69 has a first portion 71 substantially parallel to the first opening
68 arid a second portion 72 substantially perpendicular to the first
opening 68 (as well as being substantially perpendicular to the first
portion 71 of the second opening 69).
[0033] A plug 57 in which the two blades 73 and 74 passing through
the first and second openings 68 and 69 are substantially parallel is
referred to as a parallel blade plug, such as a 15 amp plug shown in
FIGS. 7 and 9. A plug 58 that has the blade 76 passing through the
second opening 69 disposed in a plane substantially perpendicular to the
,
plane in which the blade 77 passing through the first opening 68 is an
orthogonal blade plug, such as a 20 amp plug shown in FIGS. 7 and 8.
The ground prong 75 (FIGS. 4 and 6) is typically substantially D-shaped
in cross-section, and is generally longer than the blades passing through
the first and second openings 68 and 69. However, the tamper-resistant
assembly 55 shown and described does not interfere with the presence of
such a grounding plug.
[0034] Operation of the first and second shutter members 12 and 41
in the tamper-resistant assembly 55 and a more detailed description of
the tamper-resistant assembly 55 and the electrical wiring device 56 is
described in U.S. Patent No. 7,510,412 to Valentin, which may be referred to
for
further details.
[0035] As shown in FIGS. 1-3, 10 and 14, each cover member 11
includes a substantially planar surface 13 and wings 14, 15 that extend
laterally outward from opposite sides of the planar surface 13. Preferably,
an obtuse angle is formed between the wings 14 and 15 and the planar
surface 13. Tabs 16 and 17 extend from an upper side of the planar
surface 13. A hook member 18 extends from a lower side of the planar
surface 13.
[0036] As best seen in FIG. 10, the first shutter member 12 includes
a ramped surface 19 disposed between two arms 20 and 21. The ramped
surface 19 extends from a lower surface 22 to an upper surface 23. A
recess 24 is formed in the lower surface 22 and a protrusion 25 is
disposed on the upper surface 23. A blocking portion 26 is formed
rearward of the ramped surface 19. An aperture 27 in the blocking
portion 26 receives a second blade of an electrical plug when the first
shutter member 12 is moved by a first blade of the electrical plug.
[0037] Pockets 28 and 29 are disposed in the arms 20 and 21 of the
first shutter member 12. As seen in FIG. 10, the pockets 28 and 29
extend forwardly and laterally outward from opposite edges of the ramped
surface 19. Each pocket thus has a side surface 30 and an end surface
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31. Wings 14 and 15 of cover member 11 conform to the side surfaces 30
of their respective pockets 28 and 29.
[0038] To connect the cover member 11 to the first shutter member
12, the cover member 11 is moved rearward toward the ramped surface
19, as indicated by the arrow in FIG. 10. The distance between the distal
ends of the wings 14 and 15 is greater than the maximum distance
between the side surfaces 30 of the pockets 28 and 29, such that the
arms 20, 21 cause the wings to flex inwardly until they snap into the
pockets 28 and 29. At this point, an inner surface of the cover member's
planar surface 13 is disposed adjacent the ramped surface 19; the tabs 16
and 17 are disposed on opposite sides of the protrusion 25; the upper
edge 32 of the planar surface 13 (between the tabs 16 arid 17) contacts
the protrusion 25, thereby preventing further rearward movement of the
cover member 11; and the hook member 18 is received in the recess 24 in
the lower surface 22, also preventing further rearward movement of the
cover member 11. Also, the trailing edges of the wings 14 and 15 engage
the end surfaces 31 of the pockets 28 and 29, thereby preventing forward
movement of the cover member 11. The cover member 11 thus is securely
connected to the first shutter member 12 and is prevented from
independent movement when an inserted object strikes its planar surface
13, thereby protecting the shutter member's ramped surface 19 from
being marred by the insertion.
[0039] As best seen in FIG. 14, the second shutter member 41
includes a ramped surface 42 disposed between two arms 43 and 44. The
ramped surface 42 extends from a lower surface 45 to an upper surface
46. A recess 47 is formed in the lower surface 45 and a protrusion 48 is
disposed on the upper surface 46. A blocking portion 49 is formed
rearward of the ramped surface 42. An aperture 50 in the blocking
portion 49 receives a second blade of an electrical plug when the second
shutter member 12 is moved by a first blade of the electrical plug.
[0040] Pockets 51 and 52 are disposed in the arms 43 and 44 of the
second shutter member 41. As seen in Fig. 14, the pockets 51 and 52
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extend forwardly and laterally outward from opposite edges of the ramped
surface 42. Each pocket has a side surface 53 and an end surface 54. A
cover member 11 is connected to the second shutter member 41 in a
substantially similar manner as the first shutter member 12.
[0041] The first and second shutter members 12 and 41 are
preferably made of a thermoplastic, such as nylon or acetal. More
preferably, a glass-filled nylon is used to increase the structural strength
and rigidity of the manufactured parts. The cover member 11 is
preferably made of a metal, such as stainless steel or spring steel,
although any suitable material can be used. Preferably, the cover
member material is harder and more scratch resistant than the shutter
member material to withstand repeated insertions without substantially
marring or otherwise damaging the cover member and affecting
operability thereof.
[0042] The foregoing preferred embodiment, its description and its
mentioned advantages are merely illustrative and are not to be construed
as limiting the scope of the present invention. Various modifications,
alternatives and variations will be apparent to those of ordinary skill in
the art, and are intended to fall within the scope of the invention as
defined by the appended claims and their equivalents.
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