EP1642367A1 - Boitier comprenant des ouvertures defon ables destine a de l'appareillage electrique - Google Patents

Boitier comprenant des ouvertures defon ables destine a de l'appareillage electrique

Info

Publication number
EP1642367A1
EP1642367A1 EP04743124A EP04743124A EP1642367A1 EP 1642367 A1 EP1642367 A1 EP 1642367A1 EP 04743124 A EP04743124 A EP 04743124A EP 04743124 A EP04743124 A EP 04743124A EP 1642367 A1 EP1642367 A1 EP 1642367A1
Authority
EP
European Patent Office
Prior art keywords
knockout
region
enclosure
force
tear
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP04743124A
Other languages
German (de)
English (en)
Inventor
Nigel Timothy Court
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pittway Systems Technology Group Europe Ltd
Original Assignee
Pittway Systems Technology Group Europe Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Pittway Systems Technology Group Europe Ltd filed Critical Pittway Systems Technology Group Europe Ltd
Publication of EP1642367A1 publication Critical patent/EP1642367A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G3/00—Installations of electric cables or lines or protective tubing therefor in or on buildings, equivalent structures or vehicles
    • H02G3/02—Details
    • H02G3/08—Distribution boxes; Connection or junction boxes
    • H02G3/081—Bases, casings or covers
    • H02G3/083—Inlets
    • H02G3/085—Inlets including knock-out or tear-out sections

Definitions

  • the present invention relates to enclosures with knockout portions.
  • plastics enclosures for electrical equipment have portions which have weakened regions enabling them to be readily “knocked out” to allow the passage of cables, wires and so on.
  • the enclosure is made with increased weakening at the knockout perimeter to make the knockout operation easier, the inherent strength of the enclosure when containing the knockout region is also made weaker.
  • a device comprising a sheet of material having a region of weakness to effect tearing in that region upon the application of a force and focussing means for the tear force to effect precise tear propagation of the material.
  • the focussing means comprises a recess in the sheet of material directed to a region of material weakness.
  • the recess may be sized to accommodate snugly a tool for the application of force, and may be inclined to the main plane of the surface .
  • the focussing means may effect tear propagation being tear initiation and further tearing.
  • the device may have a defined edge of material in a region of material weakness to promote tearing.
  • the material weakness may be promoted by one or more of the following (i) reduced thickness in that region; (ii) increased thickness in another region; (iii) scorings, perforations or other mechanical, thermal, chemical weakness in that region; (iv) use of different materials and/or density of materials.
  • Suitable materials for the invention may, for example, be acrylonitrile butadiene styrene (ABS), polycarbonate (PC), thermoplastics, hybrids of ABS and PC, and polyester dough moulding compounds (DMC).
  • ABS acrylonitrile butadiene styrene
  • PC polycarbonate
  • DMC polyester dough moulding compounds
  • the present invention enables a well-defined predetermined aperture to be readily and quickly provided in a low-cost enclosure, pipe, duct or tray, typically made of plastics material but other materials e.g. soft metals may be used.
  • the knockout can be provided in any appropriate shape required and can have a complex (e.g. undulating) profile provided that particularly sharp changes in direction are avoided.
  • FIG. 1 is a perspective view of a knockout detail as known from the prior art
  • Figure 2 is a section view of the knockout detail of Figure 1
  • Figure 3 is a perspective view of a knockout detail embodying the present invention
  • Figure 4 is a section view of the knockout detail of Figure 3
  • Figure 5 shows the knockout detail of Figure 3 in the process of being removed.
  • Figure 1 shows a conventional knockout detail 10 in an enclosure 11 having a knockout section 12 surrounded by a circular groove 13.
  • FIG 2 is a section view across line X-X of Figure 1.
  • Knockout 12 is attached to enclosure 11 by shearable material 16.
  • the attachment between enclosure 11, knockout 12 and material 16 features sharp edges 14 and 15.
  • Knockout 12 is removed from enclosure 11 by the application of force thereto, such that shearable material 16 tears and breaks.
  • the applied force may cause tearing of material 16 at any point between sharp edges 14 and 15, resulting in an uneven, ragged hole, requiring trimming so that a cable gland or other cable termination device can be inserted through enclosure 11.
  • These ragged edges may cause damage to cables, for example chaffing due to being drawn through the aperture, especially in the case of knockout areas used for multiple cable entry.
  • the imprecise and uneven nature of the tearing, and the strength of the knockout material essential for safety requirements may necessitate an inconveniently large force to be applied.
  • the size of the aperture produced, whether or not trimming is required, is indeterminate and variable, and is most unlikely to result in a close fit with the intended cable gland, or whatever device is involved, precluding any effective sealing action, which in some instances may be an important factor.
  • FIG. 3 shows a knockout detail 20 embodying the features of the present invention.
  • Knockout 22 of thickness 3x10 " metres and circular shape with diameter 2x10 " metres is defined in enclosure 21 of thickness 3x10 metres by circular groove 23 and has a cavity 27 extending in a generally radial direction and with a base surface inclined to the plane of knockout 22.
  • FIG 4 shows a section across line Y-Y of Figure 3.
  • Knockout 22 is attached to enclosure 21 by shearable material 26, of thickness 5x10 "4 metres.
  • the attachment between enclosure 21 and material 26 features sharp edge 24, while the attachment between knockout 22 and material 26 features arcuate edge 25.
  • Figure 5 shows a stage of the tear operation for the knockout.
  • An operator employs tool 30 (e.g. a screwdriver blade) located by cavity 27, to apply force to the knockout 22 in order to tear material 26, detaching the knockout 22 from enclosure 21 and creating an aperture of a precise, predetermined size, suitable for insertion of a cable.
  • the tear initiation point 40 corresponds with the comer of tool 30.
  • Arcuate edge 25 serves to increase substantially the likelihood of shearable material 26 tearing near to sharp edge 24 when force is applied to knockout 22, thereby providing greater consistency in the dimensions and finish of the resulting aperture, by ensuring that material 26 is more resistant to shearing at arcuate edge 25.
  • Cavity 27, used to locate a screwdriver or other tool, causes the force applied using the tool to be focused in a small areas of shearable material 26, guaranteeing the location of tear initiation. This results in a gradual propagation of the tear from this location through and around material 26, and consequently minimises the force necessary to remove knockout 22 from enclosure 21. Cavity 27 at the same time provides a thicker section of material nearer the centre of knockout 22 for the tool to bear against.
  • more than one cavity 27 may be provided to ensure effective tearing of the knockout, especially when a large or complex outline shape of the knockout is required.
  • the present invention provides a knockout detail wherein the knockout force is reduced due to the focusing of force and gradual tear propagation, and the consistency of the resulting aperture is greatly improved, whilst maintaining the strength of current designs when intact.
  • knockout for cable entry
  • the invention is applicable to any appropriate geometric shape of knockout, for example a triangle, ellipse, square, rectangle, rhombus, parallelogram, polygon (given that sharp edges are softened slightly to enable the tear to continue to propagate).
  • the invention is applicable to knockouts for any appropriate type of conduit, object, or other device requiring an aperture, for example pipes, trunking, duct trays and such like.
  • Materials suitable for use as knockouts in the present invention include ABS, polycarbonate (PC) and other thermoplastics with similar characteristics, hybrids of -ABS and PC, also thermoset plastics such as polyester DMC especially with short, low-content glass fibres.

Landscapes

  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Insertion, Bundling And Securing Of Wires For Electric Apparatuses (AREA)
  • Packages (AREA)

Abstract

L'invention concerne un boîtier comprenant des ouvertures défonçables, destiné à de l'appareillage électrique. La forme circulaire des éléments défonçables (22) est définie dans le boîtier (21) par une rainure circulaire (23) et une cavité (27) qui s'étend de façon radiale et qui comporte une surface de base inclinée par rapport au plan de l'élément défonçable (22). Cet élément défonçable (22) est fixé au boîtier (21) par un matériau (26) pouvant être rompu. La jonction entre le boîtier (21) et ledit matériau (26) comprend un bord vif (24) alors que la jonction entre l'élément défonçable (22) et le matériau (26) comprend un bord arrondi (25). Pour enlever les éléments défonçables (22), l'opérateur place un outil (30) (une lame de tournevis, par exemple) dans la cavité (27) et applique une force sur l'élément défonçable (22) afin de casser le matériau (26), ce qui permet de détacher l'élément défonçable (22) du boîtier (21) et de créer une ouverture de taille précise, prédéterminée, dans laquelle peut être introduit un câble. Le point de rupture de départ (40) correspond au coin de l'outil (30). Le bord arrondi (25) de la jonction sert à augmenter sensiblement la probabilité de voir le matériau (26) se rompre à proximité du bord vif (24) lorsqu'une force est appliquée sur l'élément défonçable (22), ce qui permet d'obtenir une ouverture de dimensions et de finition plus précises, car le matériau (26) est plus résistant à la rupture au niveau du bord arrondi (25).
EP04743124A 2003-06-25 2004-06-25 Boitier comprenant des ouvertures defon ables destine a de l'appareillage electrique Withdrawn EP1642367A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0314809A GB0314809D0 (en) 2003-06-25 2003-06-25 Enclosures
PCT/GB2004/002776 WO2005002016A1 (fr) 2003-06-25 2004-06-25 Boitier comprenant des ouvertures defonçables destine a de l'appareillage electrique

Publications (1)

Publication Number Publication Date
EP1642367A1 true EP1642367A1 (fr) 2006-04-05

Family

ID=27637320

Family Applications (1)

Application Number Title Priority Date Filing Date
EP04743124A Withdrawn EP1642367A1 (fr) 2003-06-25 2004-06-25 Boitier comprenant des ouvertures defon ables destine a de l'appareillage electrique

Country Status (3)

Country Link
EP (1) EP1642367A1 (fr)
GB (1) GB0314809D0 (fr)
WO (1) WO2005002016A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102011018796B3 (de) * 2011-04-28 2012-09-06 Jacob Gmbh Elektrotechnische Fabrik Gehäusedurchführung
GB2571320B (en) * 2018-02-24 2023-06-21 Lawrence Carter Peter Spotlight bead

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2140886A5 (fr) * 1971-06-11 1973-01-19 Telemecanique Electrique
DK11278A (da) * 1978-01-10 1979-07-11 Knudsen A S Oprivningslukke

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2005002016A1 *

Also Published As

Publication number Publication date
GB0314809D0 (en) 2003-07-30
WO2005002016A1 (fr) 2005-01-06
WO2005002016B1 (fr) 2005-02-24

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