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United States Patent Application	20060201957
Kind Code	A1
Harrington; Wayne ;   et al.	September 14, 2006

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Claims

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1. An electrical enclosure plug for obstructing an aperture in an electrical fitting box, said plug comprising: a spanning member; retention apparatus extending away from said spanning member; said retention apparatus having at least a first catch depth and a second catch depth; said retention apparatus being movable on insertion to a deflected condition; and said retention apparatus being biased away from said deflected position.

2. The electrical enclosure plug of claim 1 wherein said retention apparatus includes an array of prongs.

3. The electrical enclosure plug of claim 2 wherein one prong of said array of prongs includes a first detent corresponding to a first catch depth, and one prong of said array of prongs includes a second detent corresponding to a second catch depth.

4. The electrical enclosure plug of claim 2 wherein said array of prongs includes a first set of prongs having detents corresponding to said first catch depth, and a second set of prongs having detents corresponding to said second catch depth.

5. The electrical enclosure plug of claim 4 wherein one of said sets of prongs has a radially outwardly facing set of detents, said prongs are spaced on a pitch circle, and clearance spacing between any two adjacent prongs on said pitch circle is less than 180 degrees.

6. The electrical enclosure plug of claim 4 wherein one of said sets of prongs includes at least three prongs, and said prongs are spaced on equal centers.

7. The electrical enclosure plug of claim 1 wherein said plug includes a skirt extending to one side of said spanning member, said retention apparatus extending to the same side of said spanning member.

8. The electrical enclosure plug of claim 1 wherein said spanning member includes at least one biased peripheral member, and, when said retention apparatus is at either said first or second catch depth in engagement with an electrical box, said peripheral member works in opposition to said retention member.

9. The electrical enclosure plug of claim 1 wherein said spanning member includes a peripheral spring, and, when said plug is at either said first clinch or said second catch depth relative to a wall of an electrical box, said peripheral spring engages one side of the wall of the electrical box, and said retention apparatus engages the other side of the wall of the electrical box, and said spring carries a pre-load.

10. The electrical enclosure plug of claim 1 wherein said spanning member includes a peripheral rim, and said retention apparatus is mounted to said spanning member adjacent to said peripheral rim.

11. The electrical enclosure plug of claim 10 wherein said rim includes a depending skirt that is operable in opposition to said retention apparatus.

12. The electrical enclosure plug of claim 1 wherein said retention apparatus includes an array of legs, at least some of said legs have catches, and said plug includes a biasing member positioned to work in opposition to said catches.

13. The electrical enclosure plug of claim 12 wherein said plug has a direction of insertion designated as an axial direction, and a first catch is mounted to a first leg, and said first catch includes a first cam portion, a first wedge portion, and a second wedge portion, said cam being located to cause deflection of said first leg on insertion of said plug into an aperture of an electrical box, said first wedge portion having a first slope relative to said axial direction, said second wedge portion having a second slope relative to said axial direction, said first and second wedge portions acting in opposition to said biasing member, and said first slope being steeper than said second slope.

14. The enclosure plug of claim 12 wherein said plug has a direction of insertion designated as an axial direction, and said first catch includes a wedge region formed to operate in opposition to said biasing member, said wedge region having a varying slope, said slope varying from a steeper slope away from said spanning member to a shallower slope nearer to said spanning member.

15. The enclosure plug of claim 12 wherein said spanning member includes a peripheral skirt, and said peripheral skirt has a circumferential margin, and at least one relief formed in said circumferential margin.

16. The enclosure plug of claim 12 wherein said plug is a monolithic molded part.

17. The enclosure plug of claim 12 wherein said biasing member is a peripheral skirt; said array of legs includes a first set of at least three legs mounted on a pitch circle, each of said first set of legs having a first catch, each said first catch having a cammed run-in portion, and a wedging clinch portion; each of said first catches being operable at said first catch depth; said array of legs includes a second set of at least three legs mounted on a pitch circle, each of said second set of legs having a second catch; each said second catch having a cammed run-in portion and a wedging clinch portion; and each of said second catches being operable at said second catch depth.

18. The enclosure plug of claim 17 wherein said first and second sets of legs are mounted on the same pitch circle.

19. The enclosure plug of claim 17 wherein said first and second sets of legs are intermixed.

20. The enclosure plug of claim 17 wherein said first and second sets of legs are alternately intermixed on the same pitch circle.

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Description

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FIELD OF THE INVENTION

[0001] This invention relates to enclosure plugs for blocking apertures.

BACKGROUND OF THE INVENTION

[0002] Enclosure plugs for wall apertures are used in various industries such as the automotive and electrical industries. For example, in the electrical industry sheet metal electrical boxes may be formed with perforated areas such as pre-formed frangible blanks. These are provided on walls of electrical boxes and may be knocked out as necessary to provide apertures for the installation of cables, wires, or other conduits. When the installation is complete, those apertures which do not have wiring passing through or otherwise remain in use must be blocked, and enclosure plugs are used to fill these knock-out apertures.

[0003] In general, it may be desirable to have enclosure plugs for filling knock-out apertures that may tend not to be inconvenient to install, that tend to remain in place once installed, that tend not to have increased manufacturing costs, or that may tend to accommodate only apertures in walls of a single thickness. For example, the devices of U.S. Pat. Nos. 3,392,872 and 3,902,625 both require the use of tools to install the devices into wall apertures, while the device of U.S. Pat. No. 3,358,870 would fit apertures in walls of only a certain thickness.

SUMMARY OF THE INVENTION

[0004] In an aspect of the invention there is an enclosure plug for obstructing a wall aperture. The plug has a spanning member and retention apparatus extending away from the spanning member. The retention apparatus has at least a first catch depth and a second catch depth. The retention apparatus is movable for installation into the aperture to a deflected position. The retention apparatus is biased away from the deflected position.

[0005] In an additional feature of that aspect of the invention, the present invention provides an enclosure plug for obstructing a electrical box knock-out aperture.

[0006] In another feature, the retention apparatus has an array of projections. In a further feature, the array includes one projection having retaining means corresponding to a first catch depth and one projection having retaining means corresponding to a second catch depth. In yet another feature, the enclosure plug is composed of resilient non-conductive material, preferably plastic. In yet a further feature, the spanning member includes a peripheral skirt with a circumferential margin, the circumferential margin preferably having at least one relief formed therein.

BRIEF DESCRIPTION OF THE ILLUSTRATIONS

[0007] These and other features of the embodiments of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings, by example only, and not by way of limitation, wherein:

[0008] FIG. 1 is a perspective view from above and to one side of an enclosure plug;

[0009] FIG. 2a is a perspective view from of an enclosure plug similar to the enclosure plug of FIG. 1 but of a larger size;

[0010] FIG. 2b is a plan view of the enclosure plug of FIG. 2a;

[0011] FIG. 2c is a side view of the enclosure plug of FIG. 2a;

[0012] FIG. 2d is a diametral section of the enclosure plug of FIG. 2a;

[0013] FIG. 2e is an enlarged detail of the enclosure plug of FIG. 2a;

[0014] FIG. 3 is a side view of an enclosure plug like that of FIG. 1 or FIG. 2a installed in an electrical box;

[0015] FIG. 4a shows a first view of the plug of FIG. 2a approaching installation;

[0016] FIG. 4b shows a second view of the plug of FIG. 4a in a deflected condition;

[0017] FIG. 4c shows a third view of the plug of FIG. 4a in a seated condition; and

[0018] FIG. 4d shows a fourth view of the plug of FIG. 4a in a seated condition in a thicker wall than in FIG. 4c.

DETAILED DESCRIPTION

[0019] The description that follows, and the embodiments described therein, are provided by way of illustration of an example, or examples, of particular embodiments of the principles of aspects of the present invention. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the invention. In the description, like parts are marked throughout the specification and the drawings with the same respective reference numerals. The drawings are not necessarily to scale and in some instances, proportions may have been exaggerated in order more clearly to depict certain features of the invention.

[0020] In the description that follows, reference may be made to electrical wall boxes, or junction boxes or enclosures, such as may be used to contain switches, sockets, and other electrical connections. There may also be reference to a plug for insertion into an aperture of such as box. To the extent that the plug may be for insertion into an aperture, the plug may be advanced in an insertion direction. In a cylindrical polar co-ordinate system, that direction may be defined as an axial direction, or longitudinal axis, or x-direction. Similarly, distance away from that axis may be defined as being in a radial direction, or radially, or in the direction of an r-axis. The third co-ordinate in such a polar cylindrical frame of reference is the circumferential direction, sometimes referred to as the .THETA. direction. In this type of co-ordinate system, radially inward may refer to an orientation or displacement toward the long axis of the part, radially outward, or away, may refer to orientation or displacement away from the long axis, and circumferential may refer to location, orientation or displacement about the long axis. To the extent that the plug may have a base or cap member lying predominantly in a radial-circumferential plane, items may extend longitudinally, or axially, to either side of that plane.

[0021] An aperture obstructing apparatus may be identified as an enclosure plug 10. It may be insertable into an aperture in an insertion direction, that direction running in the direction indicated generally by Arrow `A`, and which direction may be identified as the axial direction associated with axis 11. Plug 10 may be employed for blocking an aperture 14 in a wall 12. Wall 12 may be a sidewall of an electrically conductive enclosure, such as, for example, a junction box, or may be a wall in a vehicle, such as a vehicle firewall or floor pan opening. Plug 10 may include a first member that may tend to extend predominantly radially, and which may be referred to as a base wall, a head, a cap, or a cover, and which may be identified herein as a bridging or spanning member 16. Spanning member 16 may include a circumferentially extending margin or member, such as may be indicated generally as 17, and which may be a biasing member, or a reinforcing or framing member, or both. Member 17 may be in the nature of a depending skirt, or rim, 19.

[0022] Plug 10 may also include a retention apparatus, indicated generally as 18. Retention apparatus 18 may be mounted to extend axially away from spanning member 16, and may be in the nature of an array of structural members 20 mounted about the axis 11, at radial distances such as may correspond to the aperture size of a junction box, be it nominally 1/2'', 3/4'', 1'', 11/4'', 11/2'', 2'' or some other size, such as may tend to lie in the range of 3/8 inches to 3 inches. On insertion, the retention apparatus 18 may advance into the aperture, while rim 19 overhangs, or extends radially beyond, the periphery of the aperture. That is, it is too large to fit through the aperture and is prevented from advancing further by the wall surrounding the aperture.

[0023] Structural members 20 may be arranged about axis 11 such that the free circumferential gap, such as gap `G`, between any two adjacent co-operating members may subtend an angle of less than 180 degrees. Array 20 may be such that it includes a first set of members 22 that are mutually co-operating, the integers of that set being identified in one embodiment as 23, 24 and 25; and a second set of members 26 that are mutually co-operating, the integers of that second set being identified as 27, 28 and 29. It may be that each of these members has a detent, catch, or retainer, such as may be identified as 30 in the case of the members of set 22, and 22 in the case of the members of set 26. It may also be that the first set 22 has a nominal catch depth, indicated as .delta..sub.1, and the second set has a second nominal catch depth, indicated as .delta..sub.2. The first catch depth may be different from the second catch depth. These catch depths may correspond to the wall thicknesses of electrical enclosure boxes, and may, in one embodiment correspond to standard thicknesses, such as 0.085'' and 0.145''. It may be that first set 22 may be employed to retain plug 10 when engaged in a wall of a first thickness, such as .delta..sub.1, and second set 26 may be employed to retain plug 10 when engaged in a wall of a second thickness, such as .delta..sub.2, the one thickness being a lesser thickness, and the other thickness being a greater thickness. It may be that the catch depths are clinch depths in which the slope of the catch may tend to wedge the wall against the overhanging rim 19 of spanning member 16.

[0024] It may be that the members of set 22 are arranged such that there is no clear angular gap of more then 180 degrees between any two adjacent members of set 22. The clear angular gap may be less than 150 degrees. It may also be that the members of set 22 may be arranged on a pitch circle, such as 35, and may be arranged on equal pitches on that pitch circle. For example, where there are three such members, they may be spaced on 120 degree centers, with the gap spacing being 120 degrees less the width of one member taken on the radius of the pitch circle (where the members have equal widths).

[0025] It may also be that the members of set 26 are also arranged on a pitch circle, which may be the same pitch circle, 35, as the members of set 22. Again, the members of set 26 may be arranged such that there is no clear angular gap between any two adjacent members that exceeds 180 degrees, and which, in one embodiment, may be less than 150 degrees. It may be that the members of set 26 may be arranged on equal pitches on their pitch circle, and, where there are three such members, that pitch may be 120 degrees on centers, with the gap between integers being the angular pitch on centers less the angle corresponding to the arctan of the width of one member taken on the radius of the pitch circle, assuming the members to have equal width. It may be that the integers of sets 22 and 26 may be intermixed, and they may be intermixed in an alternating manner about the same pitch circle. They may be intermixed in a manner such that the integers of both sets, taken together, share common pitching between centers. The number of integers may be such that one integer is diametrically opposed to another, and it may be that one integer of set 22 may be diametrically opposed to an integer of set 26. While only two sets of integers are shown, this is intended to be generally representative of a plurality of sets of members, be there 2, 3, 4 or more such sets, each set having a different catch depth.

[0026] The base or cap portion of plug 18 may function as a biasing member. Spanning member 16 may include a central portion 34, and a peripheral edge portion, 36, such as may be formed to define the skirt, identified as rim 19. Rim 19 has a nominal, undeflected depth of section, and may tend to function as an out-of-plane stiffener of the peripheral edge of central portion 34, and of spanning member 16 more generally. The skirt, or rim, may be considered a peripheral array having a land 36, such as may bear upon the outside face of the wall member to which plug 10 is to be engaged on insertion. Land 36 may include more than one portion, such as portions 37 and 38, which may also be termed wall interface surfaces, or members, or abutments, or feet, or footings, as may be. It may by that rim 19 includes circumferential interruptions, or reliefs 40, such as may be formed through land 36, and such as may permit a toll, such as a slot head screw-driver, to be inserted in the event that it is necessary to pry plug 10 out of the aperture to which it is engaged. The removal of plug 10 from an aperture may not necessarily be a non-destructive event. That is, plug 10 may be a single use item whose removal may include the destruction or damage of plug 10 so that it may no longer be suitable for subsequent use.

[0027] The members, or integers, of sets 22 and 26 of retention apparatus 18 may be in the form of members rooted in the cap portion of plug 10. In one embodiment they may have a root 41 in spanning member 16, and a distal portion 42 extending axially away from root 41, and hence to one side and away from spanning member 16. The members of sets 22 and 26 may be referred to as legs, or fingers, or prongs, that extend away from the base defined by the cap or spanning member 16 of plug 10. Taking members 23 and 27 as being representative, such extending members may have the general form of a cantilever arm, or beam, having a built in end at root 41 that is capable of transmitting both a bending moment and a shear force, and a free end, identified as tip 44.

[0028] Each of members 23 and 27 may have a radially inwardly facing side, 46, and a radially outwardly facing side, 48. The members of sets 22 and 26 may each have a slight radially outward slope, such that the resultant array may be somewhat outwardly radially splayed, the tips 44 being wider apart than the roots 41. Radially outwardly facing side may include a run-in portion, such as may be termed a camming portion 50, adjacent to, and extending generally axially rearwardly of tip 44 (rearwardly, in the sense of opposite to the direction of insertion). Camming portion 50 may include a first lead in portion 52 and a second lead in camming portion 54 that is sloped radially outward as a function of axial station, this slope being associated with camming lead-in slope .alpha..sub.1 in the case of set 22, and .alpha..sub.2 in the case of set 26. The slope of set 22, .alpha..sub.1, may be steeper than the lead-in slope .alpha..sub.2 of set 26.

[0029] Rearwardly of camming portion 50 is a wedging, or catching, or retaining slope portion 56. Portion 56 may include a first, generally steeper initial region 58, and a second, generally more shallowly sloped region 60, the slopes associated with those regions being identified as .beta..sub.1 in the case of set 22 and .beta..sub.2 in the case of set 26; and .gamma..sub.1 in the case of set 22 and .gamma..sub.2 in the case of set 26, respectively. .gamma..sub.2 may tend to be a steeper slope than .gamma..sub.1. It may be appreciated that camming portion 50 and wedging portion 56 meet at a summit, or radially most distant point or region 62 from axis 11. It may be that for integer 23 and its co-operating integers, summit region 62 (and the other camming and wedging members) may tend to lie more axially distant from root 41 and, more particularly, from the radial circumferential plane 64 in which land 36 may lie, than does region 62 (and the other associated camming and wedging regions) of integer 27 and its co-operating integers.

[0030] When a radial force is applied to camming portion 50, integer 23 (or 27 as may be) may tend to deflect radially toward axis 11, as indicated by Arrow `B`. To the extent that this force is imposed by the inner periphery 68 of aperture 14 in a wall 70 of a junction box, or other wall riding along camming portion 50, that periphery may, for the purposes of this description, be assumed to be immovable, and a radial bending displacement will be imposed on integer 23 or 27. Since root 41 is a built-in moment connection, and root 41 is located in the relatively stiffened region of spanning member 16 adjacent to rim 19, there may be resistance to this deflection, both at root 40 and in terms of bending deflection within members 23 or 27, as may be, such that member 23 (or 27, as may be) is biased away from that deflected position and radially outward toward the original undeflected condition.

[0031] Once the summit of the camming portion passes the inner lip 72 of periphery 68, however, member 23 (or member 27 as may be) may tend to deflect radially outwardly again, as the wedging portion 56 begins to engage lip 72 of periphery 68. The radially outward force of the deflected cantilever, working on the tangent of the slope of first wedging portion, namely region 58, may tend to urge land 36 toward, and possibly against, the outward face 74 of wall 70. When land 36 abuts wall 70, any residual deflection of integer 23 (or 27) may tend to yield a clinching force to cause wall 70 to be engaged, or slightly squeezed, from both sides. Plug 10 is resilient, such that rim 19 may tend to deflect slightly in a predominantly, or entirely elastic manner when clinched, and may tend to function as a biasing member, or peripheral spring, working in opposition to the wedging portions of the retention members, rim 19 then being a biased peripheral member. The first wedging portion slope is steeper than the second portion slope, such that, initially, the axial force of the deflected cantilever working on the slope face against the wall per unit of axial deflection (yielding a spring constant, for small deflections, defined by the change in force over the change in distance) is greater, or greatest initially, and lessens if and when the second portion is reached. It may be that the change of slope point 80 between the first and second slope regimes may correspond to a standard wall depth, and it may be that at this depth it is intended that plug 10 sit in engagement with that wall, with little or axially squeezing preload in either rim 19 or axial tension in integers 23 or 27 or their co-operating members. Axially inwardly of the second wedging region is a shank region 76 that terminates at root 40. When plug 10 is in a clinch condition, there may be an axial force in member 23 or 27, as may be, tending to pull generally axially on spanning member 16, and hence on rim 19. In the case where the wall thickness is less then .delta..sub.1, the plug 10 may continue in the insertion direction with the wall riding along, shank region 76 of the integers of set 22, and being clinched, or caught, by the integers of set 26 where the wall thickness is such as to catch or clinch at .delta..sub.1, then the integers of set 26 may remain in a deflected condition. In any case, wall 70 may tend to be captured, or bracketed, between portion 56 and land 36, such that plug 10 is discouraged from being removed.

[0032] FIGS. 4a to 4c shows are sequential views as an integer of set 26, such as member 23, is inserted into a wall 70 of a thickness corresponding to catch depth d2, with FIG. 4c showing the seated position when plug 10 is engaged. The same sequence of events would apply for the introduction an integer 27 of set 26 into an aperture 14 in a wall 70 having a wall thickness corresponding to catch depth d1. In the first instance, when set 22 is in the condition of FIG. 4c, set 22 would extend beyond lip 72, and in which member 23 has sprung back to the undeflected condition. By contrast, when integer 23 is endgaged as illustrated in FIG. 4d, the members of set 26, such as integer 27, may be in a deflected condition such as shown in FIG. 4b.

[0033] The retention apparatus 18 is movable for installation into the aperture 14 into a deflected position and is biased away from the deflected position. The plug 10 may be installed by aligning the retention apparatus 18 with the aperture 14 and applying pressure on the outer surface 78 of the spanning member 16 in the forward direction of insertion parallel to axis 11 of the aperture 14, thereby forcing the retention apparatus 18 into the aperture 14. The retention apparatus 18 moves into the deflected position in order to pass through the aperture 14. As the widest portion of the detent of retention apparatus 18 completes passing through the aperture 14, at least part of the retention apparatus 18 is biased away from the deflected position. Once in place, an opposed surface of the spanning member 16, namely land 36, adjacent to the wall 12 and the retention apparatus 18 can engage the wall 12, as shown in FIGS. 5 and 6e, either to bracket and trap the wall, or, if clinched, there may be a spring load in the rim, and there may be a tensile load in the legs, namely integers 23 (or 27 as may be) and their co-operating members.

[0034] In embodiments of the invention in which the plug 10 is adapted for installation in a wall 12 of an electrical box, retention apparatus 18 may be formed of a nonconductive resilient material, such as plastic, in order to prevent shorting of wiring in such electrical box due to contact of the wiring with the retention apparatus. Plug 10 may be composed of a nonconductive resilient material. In some embodiments, plug 10 may be formed as a single moulded unit, i.e., a molded monolith.

[0035] A plug such as plug 10 may be used with an aperture having a diameter less than the diameter of the spanning member 16 as long as insertion of the plug 10 into such aperture causes the retention apparatus 18 to move into the deflected position, and provided the members of the array of retention members of the retention apparatus 18 may fit within the diameter of such aperture, it will be understood by those skilled in the art that plugs 10 may be manufactured with spanning members 16 and retention apparatuses 18 of differing dimensions to adapt them for use with apertures of varying sizes.

[0036] While the embodiments of the invention relate to enclosure plugs for electrical box knock-out apertures, the enclosure plug of the invention has application outside the electrical industry.

[0037] Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention.

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