GB2273862A - Enclosure for electrical and/or electronic equipment - Google Patents

Abstract

An enclosure for housing electrical and/or electronic equipment comprises a framework built up of elongate members (1) and at least one panel (13) which is separately formed with respect to the elongate members of the framework. The panel (13) is attached to the elongate members bounding a face of the framework to form a wall of the enclosure, and a marginal portion of the panel effects an interference fit in the groove (2) in one of the elongate members. The marginal portion of the panel has, upstanding from each surface thereof a row of mutually spaced discrete protrusions (14, 14'). <IMAGE>

Description

ENCWSURE FOR ELECTRICAL AND/OR ELECTRONIC EQUIPMENT This invention relates to cabinets, cases or other enclosures for housing electrical and/or electronic equipment and is particularly concerned with an enclosure for this purpose of the kind comprising a framework built up of upright substantially rigid elongate members mutually spaced around the periphery of the framework and substantially rigid elongate members extending substantially horizontally between and secured to the upper and lower ends of adjacent upright members of the framework, and at least one panel which is separately formed with respect to the elongate members of the framework and which is attached to the elongate members bounding a face of the framework to form a wall of the enclosure.

One form of enclosure of this kind with which the invention is especially, but not exclusively, concerned houses or constitutes a rack comprising a plurality of mutually spaced pairs of opposed guide rails into which opposed edges of circuit boards can be slid from an open front face of the enclosure.

With a view to facilitating assembly of an enclosure of the kind described, it is the practice to arrange for one or more than one of the marginal portions of a panel to effect an interference fit in a groove extending lengthwise within the adjacent elongate member bounding a part of the face of the framework of which the panel is to constitute a wall. Such an interference fit is achieved by means of a row of mutually spaced discrete protrusions which upstand from one surface of the panel along said marginal portion or each of said marginal portions, the height of the protrusions having regard to the thickness of the panel and to the width of the groove in the elongate member being such that said marginal portion of the panel will effect the required interference fit.Where the elongate members and the panel or panels of an enclosure are of a metal or metal alloy and the enclosure is to provide effective electromagnetic shielding for electrical and/or electronic equipment to be housed in the enclosure, a reliable electrical contact of low electrical resistance between the or each elongate member and the panel is essential.It is the general practice for the elongate members of the framework of an enclosure of the kind described to be extrudates of metal or metal alloy and we have found that the widths of the grooves of nominally identical elongate members can vary from member from member and/or that, in some circumstances, the act of inserting into the groove of such an elongate member a marginal portion of a panel having upstanding from one surface of said marginal portion a row of discrete protrusions can result in removal from the tops of the protrusions such an amount of metal or metal alloy as to render the fit of said marginal portion of the panel in said groove loose and unreliable and having an undesirably high electrical contact resistance.

It is an object of the present invention to provide an improved enclosure in which a marginal portion of a panel effects an interference fit in a groove of an elongate member of the framework of the enclosure, which interference fit is substantially more reliable than such interference fits hitherto proposed and used.

According to the invention, in an enclosure described above a marginal portion of a panel effecting an interference fit in the groove of an elongate member of the framework of the enclosure has upstanding from each surface of the panel a row of mutually spaced discrete protrusions so disposed that each protrusion of each row, except the protrusion at each end of said marginal portion, lies between adjacent protrusions of the other row, the height of the protrusions and the pitch of adjacent protrusions along said marginal portion having regard to the thickness of the panel and to the width of the groove being such that said marginal portion of the panel is elastically distorted into an undulating form throughout its length and each protrusion is urged into contact with the adjacent side wall of said groove.

Preferably, the pitch between adjacent protrusions of each row of discrete protrusions is uniform throughout the length of the row and, in this case, preferably also the pitch between adjacent protrusions of one row is equal to the pitch between adjacent protrusions of the other row. Each protrusion of each row of discrete protrusions, except the protrusion at each end of said marginal portion, preferably is substantially centrally disposed between adjacent protrusions of the other row.

Each discrete protrusion upstanding from each surface of said marginal portion of the panel may be of any convenient shape but preferably is a dimple of substantially hemispherical shape and, in this case, preferably also is formed by punching or otherwise effecting an indentation in the opposite surface of said marginal portion.

The elongate members of the framework and the panel or panels of the enclosure may be of metallic or non-metallic material. Where the enclosure is toprovide electromagnetic shielding for electrical and/or electronic equipment housed therein, the elongate members of the framework and the panel or panels of the enclosure will be of metal or metal alloy or for example aluminium will be of a non-metallic material having a coating of metal or metal alloy.

By way of example, for a panel having a thickness of t mm, each discrete protrusion of substantially hemispherical shape will have a maximum height, i.e. the distance between the top of the protrusion and the remote major surface of the panel, lying in the range 1.4t to 1.5t, the pitch between adjacent protrusions in each row will lie in the range lot to 100t and preferably in the range 43t to 45.5t, and the groove in the elongate member will have a width lying in the range 1.3t to 1.4t.

In addition to providing an improved enclosure of the kind described in which a marginal portion of a metal panel effects an interference fit in a groove of a metal elongate member, which interference fit provides a substantially more reliable electrical contact between said panel and the elongate member than interference fits hitherto proposed and used, an improved enclosure of the invention in which the panel or panels and elongate members are of non-metallic material will have an interference fit between a marginal portion of the or a panel and the groove of an elongate member in which the risk of any vibration between the panel and the elongate member when the improved enclosure is in service is substantially reduced. Moreover, we have found that the improved enclosure can be repeatedly disassembled and reassembled without any significant reduction in the reliability of the interference fits and, where a panel and an elongate member are of metal or metal alloy, without any significant increase in electrical contact resistance.

The invention also includes, for use in an enclosure of the kind described, an improved panel having along at least one marginal portion of the panel and upstanding from each of its surfaces, a row of mutually spaced discrete protrusions so disposed that each protrusion of each row, except the protrusion at each end of said marginal portion, lies between adjacent protrusions of the other row, the height of the protrusions and the pitch between adjacent protrusions along said marginal portion having regard to the thickness of the panel and the width of a groove in an elongate member of the framework of the enclosure in which said marginal portion is to effect an interference fit being such that, when said marginal portion effects an interference fit in said groove, said marginal portion will be so elastically distorted that it is in an undulating form throughout its length and that each protrusion is urged into contact with the adjacent side wall of said groove.

The invention is further illustrated, by way of example, by the accompanying drawings, in which: Figure 1 is a fragmental cross-sectional view of a known form of interference fit of a marginal portion of a panel in a groove in an elongate member of the framework of an enclosure for electronics equipment; Figure 2 is a fragmental cross-sectional view of a marginal portion of a preferred panel for use in a preferred enclosure according to the invention; and Figure 3 is a fragmental cross-sectional view of a preferred interference fit of a marginal portion of the preferred panel shown in Figure 2 in a groove in an elongate member of the framework of a preferred enclosure according to the invention.

Referring to the accompanying drawings, figure 1 shows part of rigid metal elongate member 1 that forms part of the framework of conventional enclosure for electrical and/or electronics equipment. The member is in the form of an aluminium extrusion that is provided with a groove 2 for receiving the edge of an aluminium panel 3 of the enclosure. In order to form an interference fit within the groove 2, the marginal portion of the panel 3 is provided with an array of protrusions 4 of generally lenticular shape that are formed by stamping indentations 5 into the opposite side of the panel.As stated above, such a form of panel has the disadvantage that the fit of the panel 3 in the groove can be unreliable and have undesirably high contact resistance due to differences in the width of grooves 2 in nominally identical members, and removal of the tops of protrusions 4 during insertion of the panel 3.

Figure 2 shows one form of an aluminium panel 13 according to the invention. In this form of panel, an array of protrusions 14 have been formed in one surface 20 by stamping indentations 15 in the opposite surface 21 of the panel, and an array of protrusions 14' have been formed in the opposite surface 21 by stamping indentations 15' in the surface 20, the protrusions 14 and 14' being arranged alternately so that each protrusion in one surface except those at the end, lies between a pair of protrusions in the opposite surface.

The height of each protrusion is about 0.4 to 0.5 times the thickness of the sheet from which the panel 13 is formed, so that the thickness of the marginal portion between peaks of protrusions 14 and 14' on opposite surfaces of the panel is about 1.8 to 2.0 times the thickness of the sheet.

When the marginal portion of the panel is inserted in the groove 2 of an elongate member 1 of an enclosure framework, as shown in figure 3, the height of the protrusions 14 and 14' arranged alternately on opposite surfaces of the panel 13 causes the marginal portion of the panel to be forced into an undulating configuration.

due to the resilience of the panel, the protrusions 14 and 14' are pushed against the sides of the groove 2 while the panel is in place thereby causing the panel 13 and elongate member 1 to have a relatively low contact resistance along their contact length.

Claims (13)

1. An enclosure for housing electrical and/or electronic equipment comprising a framework built up of upright substantially rigid elongate members mutually spaced around the periphery of the framework and substantially rigid elongate members extending substantially horizontally between and secured to the upper and lower ends of adjacent upright members of the framework, and at least one panel which is separately formed with respect to the elongate members of the framework and which is attached to the elongate members bounding a face of the framework to form a wall of the enclosure, wherein a marginal portion of a panel effecting an interference fit in the groove of an elongate member of the framework of the enclosure having upstanding from each surface of the panel a row of mutually spaced discrete protrusions so disposed that each protrusion of each row, except the protrusion at each end of said marginal portion, lies between adjacent protrusions of the other row, the height of the protrusions and the pitch of adjacent protrusions along said marginal portion having regard to the thickness of the panel and to the width of the groove being such that said marginal portion of the panel is elastically distorted into an undulating form throughout its length and each protrusion is urged into contact with the adjacent side wall of said groove.

2. An enclosure as claimed in claim 1, wherein the pitch between adjacent protrusions of each row is uniform throughout the length of the row.

3. An enclosure as claimed in claim 2, wherein the pitch between adjacent protrusions of one row is equal to the pitch between adjacent protrusions of the or each other row.

4. An enclosure as claimed in any one of claims 1 to 3, wherein each protrusion of each row of discrete protrusions, except the protrusion at each end of said marginal portion, is substantially centrally disposed between adjacent protrusions of the other row.

5. An enclosure as claimed in any one of claims 1 to 4, wherein each protrusion is a dimple of substantially hemispherical shape.

6. An enclosure as claimed in claim 5, wherein each protrusion is formed by punching or otherwise effecting an indentation in the opposite surface of the marginal portion.

7. An enclosure as claimed in any one of claims 1 to 6, wherein the elongate members of the framework and the panel or panels are formed from metal or metal alloy or from a non-metallic material having a coating of metal or metal allow.

8. An enclosure as claimed in any one of claims 1 to 7, wherein each protrusion has a maximum height in the range of 1.4 to 1.5 times the thickness of the panel.

9. An enclosure as claimed in any one of claims 1 to 8, wherein the pitch between adjacent protrusions in each row is in the range of ten to one hundred times the thickness of the panel.

10. An enclosure as claimed in any one of claims 1 to 9, wherein the groove in the elongate member has a width in the range of 1.3 to 1.4 times the thickness of the panel.

11. An enclosure substantially as hereinbefore described with reference to, and as shown in, figures 2 and 3 of the accompanying drawings.

12. A panel for use in an enclosure for housing electrical and/or electronic equipment comprising framework built up of upright substantially rigid elongate members mutually spaced around the periphery of the framework and substantially rigid elongate members extending substantially horizontally between and secured to the upper and lower ends of adjacent upright members of the framework, and at least one panel which is separately formed with respect to the elongate members of the framework and which is attached to the elongate members bounding a face of the framework to form a wall of the enclosure, the panel having along at least one marginal portion of the panel and upstanding from each of its surfaces, a row of mutually spaced discrete protrusions so disposed that each protrusion of each row, except the protrusion at each end of said marginal portion, lies between adjacent protrusions of the other row, the height of the protrusions and the pitch between adjacent protrusions along said marginal portion having regard to the thickness of the panel and the width of a groove in an elongate member of the framework of the enclosure in which said marginal portion is to effect an interference fit being such that, when said marginal portion effects an interference fit in said groove, said marginal portion will be so elastically distorted that it is in an undulating form throughout its length and that each protrusion is urged into contact with the adjacent side wall of said groove.

13. A panel for use in an enclosure for housing electrical and/or electronic equipment substantially as hereinbefore described with reference to, and as shown in, figures 2 and 3 of the accompanying drawings.