GB2230655A - Grommet - Google Patents

Abstract

A grommet for insertion in an aperture (20) through which a cable (28) is already extending. In order to fill the aperture substantially, the grommet is preferably in two parts (21, 22) which may be similarly shaped and together define an aperture for the cable. Channels at the edges of the grommet, as defined between heads of screws (29 - 31) and margin portions of the grommet, are engaged the aperture edge. Preferably the geometry of the grommet is such that the parts 21, 22 are compressed upon insertion and thus reliably held in the aperture. <IMAGE>

Description

GROMMET This invention relates to a grommet and in particular, but not exclusively, to a grommet which is insertable into an aperture after a cable/conduit has been routed through the aperture.

According to the present invention there is provided a grommet for insertion in an aperture of a wall through which an elongate element is extending, which grommet includes a plate-like member having channels at selected positions at its edges and a recess for accommodation of the elongate element, respective portions of the aperture's edge being engaged in said channels in use of the grommet.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which Fig. 1 illustrates a view of a unit into which a cable extends via an aperture which is partially filled by a grommet; Fig. 2 illustrates a plan view of the grommet of Fig. 1; Fig. 3 illustrates a cross-section through part of a grommet and the unit wall; Fig. 4 illustrates a variant of the grommet of Fig. 2 which facilitates its insertion; Fig. 5 illustrates a plan view of a first embodiment of split grommet inserted in a unit aperture of a first size with the cable extending therethrough; Fig. 6 illustrates a plan view of a second embodiment of split grommet inserted in a unit aperture of a second size;; Fig. 7 illustrates a plan view of a third embodiment of split grommet inserted in a unit aperture which is of a different shape and has limited accessibility; Fig. 8 illustrates a plan view of a fourth embodiment of split grommet inserted in a unit aperture which has walls on all sides of the cable; Fig. 9 illustrates a plan view of a fifth embodiment of split grommet, comprised of nested elements, inserted in a unit aperture; Figs. lOa to lOc illustrate installation of one split grommet part of the Fig. 5 type in a unit aperture, and Fig. lla and llb illustrates sections through part of two embodiments of grommets, having projections instead of screwheads for fixing purposes, and the unit wall.

Referring firstly to Fig. 1, there is a requirement associated with, for example, telecommunications equipment cabinets that personnel having access to the interior of the cabinet be protected from electrocution. In a particular form of cabinet there is a power supply arrangement housed at the base of the cabinet which is connected via a cable/conduit to various other units within the cabinet. The actual power supply arrangement is covered by a housing unit 1 and the cable conduit 2 extends from the housing unit 1 via an aperture 3 which is substantially greater in size than the cable/conduit cross-section.Thus not only is the cable freely movable within the aperture, with the possibility of the housing unit becoming live, if the latter is of electrically conductive material, but there is also the risk that items dropped by personnel working elsewhere in the cabinet will fall through the aperture, and that such personnel may inadvertently contact the wires of the cable since the aperture is so large.

In Fig. 1 the aperture is illustrated as partially closed by a grommet 4. This grommet 4 comprises a flat plate 5 (Fig. 2) of electrically insulating material which has a slot 6 extending thereinto, thus rendering it somewhat U-shaped. The housing unit 1 is, in the illustrated form, partially open at the back so that the aperture 3 is itself in the form of a slot. The grommet 4 as illustrated has four screws 7 inserted in the plate 5, see also Fig. 2. The plate 5 is wider than the aperture 3 as can be appreciated particularly from Fig. 3 which illustrates how the plate 5 is held in the aperture 3, namely by the side wall (edge) 8 of the aperture being held captive between the head 9 of screw 7 and the margin portion 10 of the plate 5. In the embodiment illustrated in Figs.

1 and 2 there are four such screws and thus four points of support for the plate 5. As indicated in Fig. 2 the plate may have extension arms 11 which make the length of the plate equivalent to the internal depth of the unit, thereby helping to determine the insertion of the grommet 4 in the aperture 3 although requiring a larger area grommet. To mount such a grommet after the cable 2 has been routed through the aperture 3 it is merely necessary to slide the plate in from the rear of the unit, with the edges of the aperture disposed between the screw heads 9 and the margin portions 10 of the plate.As a result of tolerances in the width of the aperture 3 and the distances between the screws 7 in the direction of the width of the aperture, the plate may not slide easily into the aperture or may, alternatively, only fit loosely in the aperture and it will then be necessary to tighten the screws to obtain a better fit. In view of the slot 6 in the plate 5 of this design of grommet, which is insertable after cable routing, the cable 2 cannot be held centrally in the aperture and away from the unit 1, as is desirable for electrical insulation purposes, and at the same time substantially fill the aperture. Furthermore there are possible problems with fitting (sliding) and loose fit, as mentioned above.

These latter problems can be obviated by suitable choice of the geometry of the grommet and material of the plate. In particular an arrangement with only three screws as illustrated in Fig. 4, as well as reducing the cost by reducing the number of screws, facilitates insertion of the grommet in the aperture and if the material and shape of the plate are such that the plate can be compressed across its width during insertion and the screw positions appropriately chosen to ensure such compression occurs, then once inserted the grommet will be held securely in position. The three screws are arranged at the apices of an acute angled triangle. A four screw arrangement which also involves compression can also be envisaged.With such a three screws compressible arrangement the grommet is first held so that one screw 13 on the two screw edge is engaged with the corresponding aperture wall at the entrance to the slot providing this aperture, the grommet is then rotated to engage the screw 12 on the one screw edge with the corresponding aperture wall, and then the grommet is slid into the aperture until the other screw 14 on the two screw edge engages the aperture wall, and compresses the grommet plate across its width so that further movement into the aperture is controlled by the friction thus induced. The basic method of insertion is described further hereafter with reference to Fig. 10.

With the grommets so far described whilst they can be inserted following cable routing, there remain the disadvantages that the aperture is only partially filled and the cable is not totally supported/guided or disposed approximately in the centre of the housing unit aperture, which is preferable on safety grounds. A two-part grommet which can be slid into an aperture in a similar manner to that described above after cable routing can, however, position, guide and support the cabling approximately in the centre of the housing unit aperture and at least substantially fill the aperture.

Various embodiments of such two-part or split grommets will now be described.

The embodiment illustrated in Fig. 5 is shown associated with a housing unit aperture 20 which is somewhat wider than it is deep. The grommet plate parts 21 and 22 are of identical shape and are slightly wider than the aperture 20 as indicated by the dashed lines.

Each plate part is generally trapezoidal in shape, one part of opposite sides 23, 24 being parallel but of different lengths, a third side 25 being normal to the said pair and the fourth side being generally at an angle to the said pair. The fourth side includes a part circular recess 27 which accommodates part of the conduit/cable 28 as illustrated and two aligned portions 26, 26a. Three screws 29, 30 and 31 are disposed in each plate, one screw 29 on the shorter side 23 and two screws 30 and 31 on the longer side 24. The wall of the aperture is held captive between the heads of the screws and the plate margins as described above.

The embodiment illustrated in Fig. 6 is shown associated with a housing unit aperture 40 which is deeper that that illustrated in Fig. 5. Once again the grommet plate parts 41 and 421 are of identical shape and slightly wider than aperture 40. The shape differs from that of Fig. 5 in that whilst one pair of sides 43, 44 are parallel and of different lengths, the difference in length is not so great as that in Fig. 5, and the third side 45 is normal to the pair of sides 43 and 44, the fourth side 46 includes a part circular recess 47 for accommodating part of conduit/cable 48 and two portions 49, 49a which are substantially parallel rather than aligned as with portions 26, 26a. Three screws 50, 51 and 52 are disposed in each plate, one screw 50 on the shorter side 43 and two screws 51 and 52 on the longer side 44.The wall of the aperture is held captive between the heads of the screws and the plate margins as described above.

The embodiment illustrated in Fig. 7 involves two grommet parts 60, 61 which have the same basic shape as those illustrated in Fig. 5. The embodiment is shown associated with an aperture 62 which differs from those previously described in that access to it is from one side rather than at the back. The access opening 63 is not as wide as before. In order to allow insertion of the grommet parts the width W of the access opening 63 must at least be equal to the screw pitch P.

The embodiment illustrated in Fig. 8 also involves two grommet parts 70, 71 which have the same basic shape as illustrated in Fig. 3. The embodiment is shown associated with an aperture 72 which has walls on all sides of the cable/conduit 73, thus there is no access opening as in the previous embodiments. For clarity the aperture is illustrated as slightly larger than the aperture. The part 70 is inserted into the aperture 72 in a similar way to the corresponding parts in the other embodiments, which is described in detail hereinafter with reference to Fig. 10, but the screw 74 of part 71 must be removable in this case in order to enable location of part 71 in the aperture and subsequently replaced when part 71 has been inserted and screw heads 75 and 76 and the respective margins of the plate part 71 have engaged the aperture wall.

The embodiment illustrated in Fig. 9 involves a two part grommet divided in a different manner to the previously described embodiments. The grommet parts 80 and 81 are nested together. The aperture 82 in this case has access from the back as in Fig. 1. Grommet part 80 is a large plate slightly wider than aperture 82 and provided with a slot 83 and is thus substantially U-shaped as described with reference to Figs. 1 and 2.

The width of slot 83 is suitable to accommodate conduit/cable 84 and is correspondingly semi-circularly shaped at its closed end for that purpose. The grommet part 81 is a small plate having a width slightly greater than slot 83, and a concave part-circularly shaped end face to accommodate the conduit/cable 84. The part 80 is secured in the aperture 82 as a result of its being wider than the aperture and the provision of screws 85,86, 87, the aperture wall being held captive as described above. The part 81 is secured in the slot 83 as a result of being wider than it and the provision of screws 88, 89 90 whereby the slot wall is held captive in a similar manner to that described above for the aperture wall.

Installation of a split grommet of the Fig. 5 type in an aperture which is open towards the rear will now be described with reference to Figs. 10a - which use the same reference numerals as Fig. 5. It is first necessary to insert grommet part 21. Since the cable 28 is not in a fixed position at this time it can be held to one side slightly whilst the part 21 complete with screws 29, 30 and 31 is slipped into position. The narrow end of part 21 is inserted first from the right hand side of slot 20 to locate the screw 29 for capture of the aperture wall opposite the aperture opening.

Part 21 is then pivoted, moving the screw 29 to the left along the aperture wall until first the screw 30 is located at the right hand part of the aperture wall which is thus captured and finally the screw 31 is located at the right hand part of the aperture wall for capture thereof and there results the compression across the width of the part 21, whereupon the part 21 is slid into its final illustrated position under the guidance of screws 29, 30 and 31, and under the control of the friction induced.

Then with the cable 28 located in the part circular section 27 of part 21, part 22 is inserted as follows. The part 22 is inserted from the left hand side of aperture 20 as indicated in Fig. 10a with screw 31 engaging and sliding down the left hand side of aperture 20 and thus capturing the wall of the latter.

The part 22 is pivoted (rotated) to engage screw 29 with the right hand side of aperture 20, thus capturing the wall of the latter. (Fig. 10b) part 22 is next slid into the aperture until the screw 30 engages the left hand side of aperture 20, thus capturing the wall of the latter. This has the effect of sideways compressing the part 22 and results in friction at the screws. The part 22 is then slid the rest of the way into the aperture (Fig. 10c) under the control of the induced friction.

The geometry of the grommet parts and the modulus of the plate material determines the sensitivity, slidability and movement thereof in the aperture. The three screws on each grommet part constrains it to follow the contours of the aperture, which preferable are parallel but which do not have to be straight as illustrated. Each grommet part is made and shaped so that it can be flexibly compressed, the slots or part-circular cut-outs providing this facility. The screws not only keep the grommet parts within the aperture but also tightening thereof may be employed to keep the cable firmly in position.

The description has so far only referred to the use of screws for maintaining the grommet parts within the aperture. Other projections secured to the plates or formed integrally therewith, Fig. lla can alternatively be used. Fig. llb illustrates such a projection which is in the form of peg 91 with a head 92 which provides the function of the screw head in the other embodiments. The head 92 may have a square cross-section. The peg 91 has a first stem portion 93 and a second stem portion 94 with a step 95 therebetween which limits the amount of insertion of the peg into an aperture of the plate 96.

The peg is held securely in the plate such as by an interference fit or suitable adhesive. The axial distance between head 92 and step 95 corresponds substantially to the thickness of the aperture wall 97.

In some of the embodiments described above peg-type projections can be used instead of all of the screws.

In other embodiments, such as Fig. 8, a screw or other removable projection, must be provided in at least one position (screw 74 in Fig. 8), although peg-type projections can be used at the other positions. The peg-type projections can have rectangular/square cross-sectioned stem portions although circular or part-curved cross-sections may facilitate insertion by enabling pivoting. The "integral" projection of Fig.

lla comprises a head portion 100, a stem portion 101 integral with plate 102, the wall 103 of the aperture being gripped (engaged) between the head 100 and the margin of plate 102. Irrespective of the type of projection involved, there is effectively defined thereby a channel at the respective portion of the grommet plate, respective portions of the aperture's edge being engaged in the channels.

Whilst the invention has been described with reference to grommet s for telecommunications equipment cabinets, this is not the only possible application of their use, There are many instances where it is required substantially to block an aperture through which a cable/conduit or other elongate member extends subsequently to routing such a member through the aperture. The two-part grommets described above enable this to be achieved in a particularly simple manner and by virtue of their geometry and the resultant compression the grommets are reliably maintained in the apertures into which they are inserted. Typically the grommet plates may be comprised of SRBF.

Whilst the apertures to be filled are substantially rectangular as specifically described, other shaped apertures could be filled by correspondingly shaped plates with appropriately positioned projections and suitable recesses for the elongate member which will provide the compressibility.

Claims (15)

CLAIMS.

1. A grommet for insertion in an aperture of a wall through which an elongate element is extending, which grommet includes a plate-like member having channels at selected positions at its edges and a recess for accommodation of the elongate element, respective portions of the aperture's edge being engaged in said channels in use of the grommet.

2. A grommet as claimed in claim 1 wherein the plate-like member has margin portions, which make it wider in a first direction that the aperture, and a plurality of projections perpendicular to the plane of the plate-like member disposed adjacent to the margin portions, each of which projections has a head portion that together with the adjacent margin portion defines said channels.

3. A grommet as claimed in claim 2 wherein the aperture has a pair of generally parallel sides spaced apart in the first direction and wherein there are three said projections, two associated with one said side and the other associated with the other said side, which projections are disposed at the apices of an acute angled triangle.

4. A grommet as claimed in claim 2 or claim 3 wherein the material and geometry of the plate-like member and the positions of the projections are such that when inserted in the aperture the plate-like member is compressed and forces result which ensures that the plate-like member is reliably held in position in the aperture.

5. A grommet as claimed in claim 2 wherein the aperture has a pair of generally parallel sides spaced apart in the first direction, wherein the plate-like member is divided into two portions, each of which portions has three said projections.

6. A grommet as claimed in claim 5 wherein the two portions have the same shape and size.

7. A grommet as claimed in claim 6 wherein the portions are generally trapezoidal with a pair of parallel sides spaced apart in the first direction, one of which sides is longer than the other, a third side substantially perpendicular to the parallel sides, and a fourth side generally angled with respect to the first direction and including a part circular recess, which part circular recesses together define said recess for the accommodation of the elongate element.

8. A grommet as claimed in claim 5 wherein one portion is larger than the other, has a central slot whereby to partially define the recess and is generally U-shaped, and wherein the other portion is of dimensioned and shaped such as to substantially fill that part of the central slot not occupied by the elongate member.

9. A grommet as claimed in any one of claims 5 to 8 wherein the three said projections in each said portion are disposed at the apices of respective acute-angled triangles.

10. A grommet as claimed in claim 7 wherein the aperture is a closed aperture, wherein the portions are inserted one after the other and the last to be inserted portion has a projection which is removable to enable it to be so inserted and replaceable following insertion.

11. A grommet as claimed in any one of the preceding claims wherein the projections are comprised at least partly by screws.

12. A grommet as claimed in any one of claims 2 to 10 wherein the projections are composed at least partly by members formed integrally with the plate-like member of the portions thereof.

13. A grommet as claimed in any one of claims 5 to 10 wherein the two portions are such that when inserted in the aperture the elongate element is positioned substantially centrally of the aperture.

14. A grommet as claimed in claim 9 as appendant to claim 7 wherein one said projecton is associated with the shorter of the two sides of the plate-like member portions, and two said projections are associated with the longer of the two sides.

15. A grommet substantially as herein described with reference to and as illustrated in the accompanying drawings.