GB2127892A - Door hinge - Google Patents

Abstract

In order to prevent a thief from opening a closed door by removing the door hinge pins, a door hinge is provided on one leaf (1) with a hardened steel plug (6) arranged to be received in an aperture (18) provided in the second leaf (2) when the leaves are closed. On removal of the hinge pin (3) the plug prevent the door from being opened. The plug is rotatably secured to the first leaf (1) by a circlip (11) (Fig. 2), and a clearance is provided between the plug (6) and the margin of the aperture (8) to facilitate rotation of the plug in the event that an attempt is made to saw through the plug. <IMAGE>

Description

SPECIFICATION Door hinge This invention relates to a door hinge.

With a conventional door hinge it is often possible for a thief to remove the hinge pin when the door is closed and thereby release the door when the door is locked.

The object of the invention is to provide a hinge which will retain a locked door in position in the event that the hinge is removed.

According to the invention a door hinge comprises first and second hinge leaves pivotally connected together, a plug carried by the first leaf, and an aperture provided in the second leaf, the arrangement being such that when the leaves are in a closed position the plug projects into the aperture.

The plug will then retain a door against opening in the event of removal of the hinge pin, provided of course that the hinge is mounted on the door such that the hinge leaves are closed when the door is closed.

Preferably the plug is made of a hardened material which will resist sawing, such as hardened steel.

In order to make it even more difficult for the plug to be sawn, the plug is preferably mounted on the first leaf for rotation about the plug axis, and said aperture is sized to provide clearance between the second leaf and the plug to enable the plug to rotate freely with the hinge leaves in the closed position.

Preferably the plug is of substantially cylindrical shape.

When the hinge leaves are flat, said aperture is preferably round to receive the plug.

In one preferred embodiment the hinge leaves are cranked when viewed parallel to the pivotal axis of the hinge, and the aperture is elongated in a direction transverse to said pivotal axis.

The plug is preferably located at substantially the mid-height of the hinge, so that if an attempt is made to saw through the plug it will be necessary to saw down approximately half the length of the hinge before the plug is reached by the saw.

The plug is preferably held captive to the first leaf by at least one circlip which is located in an annular recess in the plug and on the side of the first leaf that is remote from the closed second leaf.

Two door hinges in accordance with the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a side elevation of a first hinge in its fully open condition; Figure 2 is a horizontal cross-sectional view of the hinge of Fig. 1 at its mid-height, shown in full outline in its closed condition, the open position of one leaf being shown in discontinuous outline; Figure 3 is a side elevation of a second hinge; and Figure 4 is a plan view of the hinge of Fig.

3 but partly sectioned at its mid height, the open position of one leaf being shown in discontinuous outline.

With reference to Figs. 1 and 2, the flat oblong-rectangular hinge leaves 1, 2 in this case are of brass and are pivotally connected together by a plain, brass hinge pin 3 extending through knuckles 4. Each lead has four countersunk screw holes 5.

At the mid-height of first leaf 1 is provided a rotatable, hardened steel plug 6 of which the axis extends substantially normally of the plane of leaf 1. As shown in Fig. 2, the plug comprises a larger diameter portion 7 which projects through a hole 8 provided in the second leaf 2 when the hinge leaves are closed, and a coaxial smaller diameter portion 9 which is a freely rotatable fit in a hole 10 provided in leaf 1. An annular recess is provided in that part of portion 9 which projects from the back of leaf 1 to receive a circlip 11 which holds captive the plug 6 to the first leaf.

The free end of the plug 6 is radiused at 11 to enable the plug 6 to enter hole 8 yet in the closed condition of the leaves to be a relatively close fit in hole 8, but with clearance to permit free rotation of the plug 6.

Since the plug is rotatable, any attempt to saw through the plug will result in rotation of the plug.

The use of a plug incorporated in a hinge, as compared with mounting a plug on a door independently of the hinge, enables a relatively close but rotatable fit to be achieved between the plug and hole 8 since the relative positions of the plug and hole 8 are determined in manufacture. This ensures that little movement, if any, of the door is permitted by the plug 6 in the event that the hinge pin is removed by a thief.

Since the plug is incorporated in the hinge, the hinge can be mounted in the usual way, providing that a small recess is provided in the door or door frame to receive the circlip 11.

In Figs. 3 and 4 parts corresponding to those of the hinge of Figs. 1 and 2 have been given corresponding reference numerals. The hinge of Figs. 3 and 4 comprises hinge leaves 1 and 2 which are seen to be cranked when viewed in plan.

In order to accommodate entry of the plug 7 into hole 8 during closing of the hinge leaves, the hole 8 is made of oval shape, as shown in Fig. 3. In the closed position of the hinge, as shown in Fig. 4, the plug 7 is closely adjacent to the margin of hole 8, except on the side remote from hinge pin 3, but is spaced therefrom to permit free rotation of the plug 7.

Claims (9)

1. A door hinge comprising first and second hinge leaves pivotally connected together, a plug carried by the first leaf, and an aperture provided in the second leaf, the arrange ment being such that when the leaves are in a closed position the plug projects into the aperture.

2. A door hinge as claimed in claim 1 in which the plug is mounted on the first leaf for rotation about the axis of the plug, and the aperture is sized to provide clearance between the second leaf and the plug to enable the plug to rotate freely when the hinge leaves are in the closed position.

3. A door hinge as claimed in claim 1 or claim 2 in which the plug is of substantially cylindrical shape.

4. A door hinge as claimed in claim 3 in which the hinge leaves are substantially flat, and the aperture is round.

5. A door hinge as claimed in claim 3 in which both hinge leaves are cranked when viewed parallel to the pivotal axis of the hinge, and the aperture is elongated in a direction transverse to said pivotal axis.

6. A door hinge as claimed in any of the preceding claims in which the plug is located at substantially the mid-height of the hinge.

7. A door hinge as claimed in any of the preceding claims in which the plug is held captive to the first leaf by at least one circlip which is located in an annular recess in the plug and on the side of the first leaf that is remote from the closed second leaf.

8. A door hinge substantially as described with reference to Figs. 1 and 2 of the accompanying drawings.

9. A door hinge substantially as described with reference to Figs. 3 and 4 of the accompanying drawings.