GB2250543A - Lattice frame closer - Google Patents

Abstract

A lattice frame closer is provided to overcome problems with resistance to opening and closing a lattice frame. A lattice frame comprises an array of arms (3), and a plurality of pivot points (6, 7) around which the arms pivot, and a means for applying a biasing force to one or more pivot points is provided to bias the lattice frame towards the extended position. The biasing means comprises a cylinder (21) housing a piston (24) and a spring (23), the spring urging the piston against a pivot point. The pivot points are arranged in pairs, and the biasing means are arranged in opposed pairs, with one pair acting downwards on an upper pivot point, and the other of the pair acting upwards on a lower pivot point. <IMAGE>

Description

LATTICE FRAME CLOSER This invention relates to a lattice frame closer, in particular to a closer applicable to a lattice frame door.

Lattice frame doors are often used in lift cages. It is desirable that the lift door closes automatically behind passengers as they leave. There are various devices used to close such doors using levers, pulleys, and coil springs. Such devices involve mutilation of the door or body of the cage, or are bulky and unsightly, offer significant resistance to opening the door, or close the door too fast.

In its broadest form, the invention resides in a device for applying a biasing force to one or more of the pivot points of a lattice frame to urge the frame towards an extended position.

More specifically the invention provides an apparatus for closing a lattice frame assembly, the lattice frame being extensible and retractible by pivoting an array of arms about a plurality of pivot points, the apparatus comprising means for applying a biasing force to one or more pivot points to bias the frame towards the extended position.

Preferably the biasing means applies the biasing force in a direction normal to the direction of expansion and retraction.

Preferably, the biasing means comprises a spring which urges a piston against a pivot point. The piston is preferably housed within a cylinder and an adjustor may be arranged between the end of the cylinder and the spring to vary the biasing force.

The spring is preferably a compression spring. The apparatus of the invention is particularly applicable to lattice frame doors, for example, as used on lifts. It is desirable that the lattice door closes automatically and apparatus embodying the present invention may be used to achieve this aim. As the user opens the door manually against the bias of the spring, the bias force must be chosen sdch that undue force is not required to be exerted by the user while retaining acceptably quick closure.

Preferably biasing means are applied at several pivot points in lattice and in an especially preferred arrangement the biassing means are arranged in opposed pairs with one of the pair acting downwards on an upper pivot point and the other of the pair acting upwards on a lower pivot point.

An embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 shows the general arrangement of a lattice door and the possible positions for the lattice frame door closers.

Figure 2 shows a detailed side view of a lattice door closer in position.

Fissure 3 shows a cross-sectional front view of the closer in position.

Figure 4 shows a simplified version of the spring force adjustment.

A typical lift-cage door arrangement comprises a system of vertical primary and secondary bars 1 and 2 respectively in fig 1, joined by a rhomboid lattice of diagonal bars 3 and suspended on rollers 4 from a horizontal supporting guide rail 5.

As the door is opened and closed the lattice bars pivot about their fixed centres 6 and 7 causing their outer joints at 8, 9,10 and 11 to rise and fall.

A downwards force acting at 8 and 10 or an upwards force at 9 and 11tends to force the lattice to open, thus closing the door. The following example shows how such å force can be applied at point 8, the same principle being applicable at points 9,10, ad11.

Figure 2 shows a section across a primary vertical bar. These bars are doubled to straddle the guide rail 5 and may also be suspended by a roller on a shaft 4. For the purposes of applying the force, the only important feature is the presence of short cross-bars rigidly fixed to the vertical ones at positions 12,13 and 14 in fig 1. a specific instance of which is shown at 15 in fig 2.

These cross bars provide suitable anchoring points for one end of a spring mechanism as shown in fig 3. The other end of the spring mechanism presses down on anouter joint of the lattice frame at position 8. This outer joint comprises a short shaft 16 about which the two:lattice bars 17 and 18 pivot.

As the door isa-gene-d and closed this shaftsj des vertically within thehollow 'U" section of the primary vertical bars at 19 and 20.

The spring mechanism comprises an outer cylinder 21, a screw plug to adjust the spring force 22, a compression spring 23 and a freely moving piston 24.

The spring is selected sorthat the whole unit presses firmly at all times against the cross bar 15 and the lattice joint shaft 16. In order to prevent the unit from slipping out of position sideways there are two lugs 2 protruding at the upper end of the cylinder and the piston has a cut-out 26 to match the form of the of the lattice pivot shaft 16. A simpler variation has spacers 27 inserted above the spring to adjust the force, in which case the spacers are retained by lugs 28.

As tube'door is ppened, the lattice pivot shaft rises, forcing the piston 24 to aompness the spring 23. The spring applies a steadily increasing restoring force so that when the doors released if pushes the lattice pivot shaft 16 down, forcing the lattice open and closing the door. The force can be adjusted using the screw plug 22 or the spacers 27 to ensure that the door closes smoothly and quietly and offers little resistance to opening.

If it is necessary to secure the mechanism to the framework this can be achieved without modification of the framework by passing one spring or wire loop through holes drilled in the upper half of the cylinder and round the cross bar 15 and another spring or wire through a hole drilled in the lower half of the piston and round the lattice frame pivot shaft 16.

Claims (8)

1. A lattice frame closer for closing a lattice frame, the lattice frame comprising an array of arms, and a plurality of pivot points, the lattice frame being extensible and retractable by pivoting of the arms about the pivot points, the lattice frame closer comprising means for applying a biasing force to one or more pivot points to bias the lattice frame towards the extended position.

2. A lattice frame closer according to claim 1, wherein the biasing means is arranged to apply the biasing force in a direction substantially normal to the direction of extension and retraction of the frame.

3. A lattice frame closer according to claim 1 or 2, wherein the biasing means comprises a cylinder housing a piston and a spring, the spring urging the piston against a pivot point.

4. A lattice frame closer according to claim 3, wherein the spring is a compression spring.

5. A lattice frame closer according to claims 3 or 4, wherein an adjuster is arranged between the spring and the cylinder to vary the biasing force.

6. A lattice frame closer according to any of claims 1 to 5, wherein the lattice frame comprises a plurality of the said biasing means each for applying a biasing force at an individual pivot point of the lattice frame.

7. A lattice frame closer according to claim 6, wherein the pivot points and the biasing means are arranged in opposed pairs, the biasing means acting to urge the pivot points of a pair in opposite directions.

8. A lattice frame closer substantially as herein described with reference to figures 2 and 3, or 2 and 4 of the accompanying drawings.