GB2378587A - Floor boxes having a spring biased ratchet locator - Google Patents

Abstract

In a floor box of a type having a box frame (62) and comprising a plurality of retractable blades (64), which in use engage beneath a floor opening (56) to clamp the frame in position, each blade (64) is held in an extended position by an outwardly biased ratchet mechanism (78, 82 and 84). The ratchet may comprise a coil compression spring (78) acting against the frame, and a spring pawl (82) integral with the blade and engageable with teeth (84) formed on the frame.

Description

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Title: Floor Boxes Field of the invention This invention relates to floor boxes, and more especially to electrical outlet boxes which provide electrical terminals in an underfloor cabling system and to which flying leads can be connected from above the floor from telephones, electrical equipment, computers and the like.

Background to the invention Mountings for floor boxes basically comprise a box frame for securing the box to the edge of an opening in the floor, and a carpet frame and lid assembly which holds down the edge of the carpet around the floor opening. Both the box frame and the carpet frame and lid assembly require to be secured to the floor and there exist several known arrangements for this purpose.

In one arrangement the box frame fixes to the floor and has an internal projecting flange to which an inner edge of the carpet frame beneath the lid secures by fixing screws. In another arrangement, in which the carpet frame and box frame are integrally connected, the box frame carried a member which engages the underside of the floor, and a carpet frame screw fixes to this member to clamp the entire assembly in position. Another recent proposal is to replace the fixing screws of the first-mentioned arrangement by a ratchet mechanism.

In EP-A-0656676 there is disclosed a floor box of a type having a frame unit carrying a plurality of retractable blades which in use engage beneath the floor at the edge of the floor opening to clamp the frame unit in position. Such a floor box is hereinafter referred to as a-floor box of the type described".

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It is an object of the present invention to provide an improved floor box of the type described which enables the box to be easily and securely mounted in floor openings of various thicknesses.

Summary of the invention According to the present invention, in a floor box of the type described each blade is held in an extended or projected position by an outwardly biassed ratchet mechanism.

The blade is preferably biased outwardly by a compression spring acting against the box frame.

The ratchet mechanism may comprise a spring pawl integrally formed on the blade; and the pawl may be upwardly directed to engage with teeth formed on the box frame.

To enable the floor box to be adjusted, for example during installation, the spring pawl is preferably formed with a lateral extension to enable the pawl to be manually moved out of engagement with the ratchet teeth.

Advantageously the blade is formed at its outer edge with a steep ramp, which is preferably serrated to provide a plurality of teeth or steps for engaging a corner edge of the floor opening.

The steep ramp enables a large range of floor thicknesses to be accommodated, the ratchet mechanism ensuring that the blade cannot involuntarily be retracted once in position against the floor opening.

Brief description of the drawings A floor box in accordance with the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

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Figure 1 is a diagrammatic cross-sectional view at one side of a floor aperture in which a known floor box is received; Figure 2 is a side view, partly in section, of an improved floor box arrangement in accordance with the invention; Figure 3 is an enlarged detail of a ratchet mechanism of the floor box in operation; Figure 4 is a side view showing the blade; Figure 5 is an end view of the blade shown in Figure 4; Figure 6 shows the blade in perspective; Figure 7 is an enlarged detail view of the serrated ramp of the blade; and Figure 8 is an enlarged detail of a spring pawl formed on the blade.

Detailed description of the drawings The principle of the arrangement of the known floor box will be understood from Figure 1 The floor 10, having a carpet or floor covering 12, is formed with an aperture 14 in which is mounted a floor box 16, typically an electrical outlet box in an underfloor cable system.

In use, terminals in the box are accessible through an openable lid 17 in the floor, which lid forms part of a carpet frame and lid assembly 18.

The box 16 is held in place by a box frame 20 to which a plastics carpet frame 22 is secured by fixing screws 24 (only one shown).

The entire assembly requires to be mounted firmly in place in the floor aperture. This is achieved by means of two pairs of outwardly urged blades 26, one blade at each corner of the box, each pair being biased outwards by a compression spring 28.

One of the blades 26 is shown in Figure 1 and it will be seen that it has a ramp surface 30 at its outer end, where the blade engages the underside of the floor when it is projected outwardly of the box frame 20 via the spring 28. The assembly is thus fixed in position by the clamping action on the edge of the floor around the aperture 14 by the carpet frame 22 and blade 26. Different thicknesses of floor covering 12 are automatically catered for and,

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by pressing down on the carpet frame during fitting, maximum projection of the blade is ensured to achieve a strong clamping action.

An improved floor box in accordance with the invention, which operates on a similar principle to that of the known box of Figure 1, is shown in Figures 2 to 8.

Referring first to Figure 2, a raised floor 52 is covered by carpet tiles 54, and has a cut out 56 in which is mounted a rectangular floor box 58 incorporating a rim or lip 60 which sits over the carpet tiles 54. Electric terminals (not shown) in the box are accessible via a lid (not shown) which fits within the rim 60 and is preferably hinged to the box. The box comprises a frame 62, and in the one corner shown in the drawing is slidably mounted a clamping blade 64. It will be understood that a similar blade (not shown) is mounted at each of the three other corners of the frame, one blade being disposed to the left of Figure 2 to face in the opposite direction to blade 64.

The box, including the blade, is preferably formed of a thermoplastics material by an injection moulding process.

As best seen in Figures 4 to 7, at its outer edge the blade has a steeply inclined ramp formed with a plurality of small serrated teeth or steps 66, which serve in use to engage under the lower edge 68 of the cut out 56 in the floor 52.

The inner side of the blade has a cheek 70 from which a pair of T-shaped slides 72 project to the outer side of the blade. The slides engage in a horizontal slot 74 in the frame 62, thereby guiding the blade to slide horizontally in or out.

Above the cheek 70 the blade carries a plastic mandrel 76 on which is mounted a coil compression spring 78. The outer end of the mandrel passes slidingly through a lug 80 projecting from the frame 62, against which the spring 78 is compressed.

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Integrally formed at the top of the blade is a spring pawl 82 which engages with a series of ratchet teeth 84 formed on the underside edge of the box frame. The pawl 82 can be manually disengaged from the teeth 84 by means of a finger 86 projecting from the side of the pawl, as best seen in Figure 8.

At the upper left-hand corner of the blade, as viewed in Figure 2, a rectangular arm 88 projects upwardly and slightly outwards towards the box frame. When the blade is fully retracted, by manually pressing down the finger 86 to disengage the pawl 82 from the teeth 84 and drawing back the finger (and hence the blade), the arm 88 can engage behind a stop 90 formed on the box frame, thereby securing the blade in a locked position, eg while the box is being installed.

An important advantage of the floor box described above, is that the steep angle of the blade ramp enables a large range of floor thicknesses (including carpet tiles) to be catered for. In that the blade can be locked in its extended position, by virtue of the ratchet mechanism, it is ensured that the floor box is firmly wedged in situ and will resist any upward force which might be exerted on the box.

Additionally, it is ensured that if there is for example heavy walking traffic over the floor box, any resulting reduction in the effective floor thickness (particularly compression of the carpet tiles) will automatically be taken up by the blade being biased further outwards, while the pawl engages with a subsequent ratchet tooth to maintain the new clamping position.

Claims (8)

1. C1090. 00/A CLAIMS 1. A floor box of a type having a frame unit carrying a plurality of retractable blades which in use engage beneath the floor at the edge of the floor opening to clamp the frame unit in position, in which each blade is held in an extended or projected position by an outwardly biased ratchet mechanism.
2. 2. A floor box according to claim 1 in which the ratchet mechanism comprises a compression spring acting against the box frame.
3. 3. A floor box according to claim 2 in which the ratchet mechanism further comprises a spring pawl integrally formed on the blade.
4. 4. A floor box according to claim 3 in which the pawl is upwardly directed to engage with teeth formed on the box frame.
5. 5. A floor box according to claim 3 or claim 4 in which the spring pawl is formed with a lateral extension to enable the pawl to be manually moved out of engagement with the ratchet teeth, so as to allow the floor box to be adjusted during installation.
6. 6. A floor box according to any one preceding claim in which the blade is formed at its outer edge with a steep ramp.
7. 7. A floor box according to claim 6 in which the steep ramp is serrated to provide a plurality of steps for engaging a corner edge of the floor opening.
8. 8. A floor box substantially as herein described with reference to, and as illustrated in, Figures 2 to 8 of the accompanying drawings.