GB2175044A

GB2175044A - Letter plates

Info

Publication number: GB2175044A
Application number: GB08512616A
Authority: GB
Inventors: Andrew James Sharam
Original assignee: GLOSTER PLASTICS Ltd
Current assignee: GLOSTER PLASTICS Ltd
Priority date: 1985-05-18
Filing date: 1985-05-18
Publication date: 1986-11-19
Also published as: GB2175044B; GB8512616D0

Abstract

A letter plate comprising a frame 10, 13 and a flap 18 hingedly connected to the frame 10, 13 along one edge, to cover an opening 11 therein, and spring means in the form of a torsion bar 25 having tongues 26, 27 at opposite ends respectively the tongue 26 at one end being located in a slot in the flap 18 and the tongue at the other end engaging in an opening 16 in the frame, pretensioning of the torsion bar being arranged to bias the flap towards the closed position. <IMAGE>

Description

SPECIFICATION Letter plates This invention relates to letter plates of the kind comprising a frame defining a generally rectangular aperture and having means whereby it can be secured to a door or other structure and a flap hinged to the frame and having spring means urging it into a position in which it normally closes the aperture but from which it can be swung to reveal the aperture, to allow letters or other matter to be passed through.

Conventional letter plates have been provided with torsion or other metal springs and hinge fittings but it has been proposed to employ a spring in the form of a plastics rod which has its ends anchored so as to act as a torsion bar tending to hold the flap in its closed position against the frame, to close the aperture. This has the advantages of simplicity in manufacture and assembly as well as being reliable and compact and also proof against corrosion, to which metal springs are subject.

It is the object of the present invention to provide a letter plate having a torsion bar spring system which is particularly effective and reliable in use.

According to the invention there is provided a letter plate comprising, in combination, a frame defining an aperture and a ftap connected by hinge members at opposite sides of the frame and arranged to swing between a closed position, covering the aperture and an open position in which the aperture is exposed and spring means acting between the frame and the flap, said spring means comprising a torsion bar having, at one end, a formation extending laterally of the bar and engaging in a slot in the flap, to locate that end of the torsion bar against rotation relatively to the flap and at the other end, a further formation also extending laterally of the torsion bar and locating in an opening in the frame adjacent to the flap and at a position spaced from the ends of the flap.

The invention will now be described by way of example with reference to the accompanying drawings in which the single figure is an exploded perspective view of a letter plate constructed in accordance with the invention.

The letter plate shown comprises a hollow rectangular frame 10. In this example the frame is made of plastics material as a moulding and defines a rectangular aperture 11. The shorter sides of the rectangular frame are provided with sets of holes 12 to accept fixing screws by means of which the assembly can be secured to a door or other structure either directly or through another similar letter plate assembly mounted at the opposite side of the door or structure.

A second component 13 of the frame also made as a plastics moulding, has a flanged shallow rectangular tubular form. The tubular portion 14 is arranged in use to extend within the door or structure and can co-operate with a similar tubular portion on a letter plate assembly mounted at the other side of the door or structure, in telescopic manner. Trapped between the frame 10 and the second component 13 may be a soft seal (not illustrated).

The frame 10 and component 13 are secured together as by welding and the frame has location pegs 15 by means of which the parts are held correctly assembled prior to welding.

The frame 10 has a hole 16 situated at a position along the longer side of the aperture 11 and at the upper side of the frame, when this is fitted in use. Aligned with the hole 16 is a slot 17 in the component 13. The slot 17 is formed in the upper flange and when the frame and further components are welded together the hole 16 and slot 17 are aligned to provide a through opening from front to back of the frame assembly.

A flap 18 is provided to close the aperture 11 in use. The flap can swing from a normal position, closing the aperture, to an open position in which the aperture is exposed. The flap in this example is a metal extrusion having along its upper edge a C-section formation defining a circular section recess 19 having a narrower slot 20. The flap is made with constant cross-section and is conveniently produced by extrusion.

However at a position spaced from one end of the flap the slot 20 is enlarged at 21.

The two ends of the flap receive hinge pins 22, 23 by means of which the flap is hinged in the frame. The frame 10 has respective holes 24 in the shorter sides and the hinge pins 22, 23 are headed. The larger head portions of the pins are in tight frictional engagement in the holes 24 and the smaller ends of the pins engage in the ends of the recess 19 extending through the length of the flap 18.

The letter plate can be used in this form in which case the flap is simply urged towards its closed position to cover the aperture 11, by gravity. However, where the flap is to be spring urged towards its closed position to cover the aperture 11, a torsion bar spring means 25 is used. This is formed from a suitable plastics material such as nylon having a degree of resilience. It comprises a straight rod with locating formations 26, 27 at its two ends respectively. In the free position, as shown in the drawing, the formations 26, 27 are at right angles. The formation 26 is a shallow tongue which has a width approximating to that of the slot 20 in the flap 18. The bar 25 is located within the recess 19 and the tongue 26 extends into the slot 20, thus securing that end of the rod 25 against rotation relatively to the flap 18.

The other end of the rod has the formation 27 which is a longer tongue. This passes through the enlargement 21 of the slot 20 in the flap and into the hole 16 and slot 17 in the frame 10 and component 13. In order to reach this position, the tongue has to be rotated through approximately 90 , thus giving pre-tension to the spring to urge the flap into its closed position.

As the flap is raised, in use, towards its open position the bar 25 is further stressed in torsion and movement of the flap is permitted by means of the clearance afforded by the enlargement 21 of the slot 20. The confines of the enlargement 21 serve to limit the travel of the flap and in use the fully open position of the flap may be substantially at right angles to the general plane of the frame, that is, generally horizontally when the assembly is in a position of use.

The spring means 25 has a length and torsional strength calculated to provide the required spring force on the flap and the position of the ends of the spring means may be varied according to requirements.

The flap, in the closed position, will locate against the seal which is trapped between the frame 10 and component 13, thus providing a weather seal.

The frame and flap may be constructed from different materials to provide differing decorative appearance and a number of different sizes can be produced.

Claims

1. A letter plate comprising, in combination, a frame defining an aperture and a flap connected by hinge members at opposite sides of the frame and arranged to swing between a closed position, covering the aper ture, and an open position in which the aperture is exposed; and spring means acting between the frame and the flap, said spring means comprising a torsion bar having, at one end, a formation extending laterally of the bar and engaging in a slot in the flap, to locate that end of the torsion bar against rotation relatively to the flap and at the other end, a further formation also extending laterally of the torsion bar and locating in an opening in the frame adjacent to the flap and at a position spaced from the ends of the flap.

2. A letter plate as claimed in Claim 1 in which the torsion bar is formed as one piece with the formation at one end and the further formation at the other end being respective tongues extending laterally of the bar and being set at different angles relatively to the centre of the bar, when the torsion bar is in its free, unstressed condition.

3. A letter plate as claimed in Claim 1 or Claim 2 in which the flap is slotted throughout its length and the torsion bar is substantially enclosed therein with the said formation on the torsion bar engaging with the edges of the slot at a position near the centre of the flap.

4. A letter plate as claimed in any one of the preceding claims in which the frame is made from two components secured together and the opening in which the further formation on the torsion bar fits is defined, in part, between the two components.

5. A letter plate -as claimed in any one of the preceding claims in which the flap is hingedly connected to the frame by means of plugs engaging in holes in the frame and in opposite ends of a slot extending throughout the length of the flap.

6. A letter plate substantially as hereinbefore described with reference to and as shown in the accompanying drawings.