GB2209557A

GB2209557A - Lock protection device

Info

Publication number: GB2209557A
Application number: GB8820512A
Authority: GB
Inventors: Peter Banham
Original assignee: Banham Patent Locks Ltd
Current assignee: Banham Patent Locks Ltd
Priority date: 1987-09-04
Filing date: 1988-08-30
Publication date: 1989-05-17
Anticipated expiration: 2008-08-30
Also published as: GB2209557B; GB8820512D0

Abstract

A device to prevent forcing of a spring-loaded bolt consists of a plate (2) attached to the outer face of a door (6) adjacent the door frame and at the level of the bolt. The plate has a limb (22) which projects outwards from the door (6), and which, when the door (6) is closed, lies in a channel created by inwardly curved portion (34) of plate (4), this arrangement blocks any pathway past the edge of the door for an attempt to force the bolt back by slipping in a flexible card. <IMAGE>

Description

LOCK PROTECTION DEVICE The present invention concerns a lock protection device for doors to prevent the bolt of a night latch on the door from being slipped by insertion of a resilient flexible material around the edge of the door.

It is well known that some night latches can be slipped by inserting a piece of thin mica or flexible plastic through the gap between the door and the door frame, so as to push back the spring-loaded bolt and thereby release the door. Although door frames are generally rebated so that the overlapping portion of the door frame shields the gap between the door and the frame, this danger can still occur if the door and door frame are not a very close fit.

The object of the present invention is to prevent opening of the door in this manner. Accordingly the invention provides a lock protection device for a night latch or other lock having a spring-loaded bolt which device comprises a first plate having means by which it can be secured to the front or outer face of a door at the level of the lock and such that a part of the plate will project outwardly therefrom, adjacent the door frame, and a second plate having means for it to be secured to the door frame at the level of the first plate, and comprising a part which extends inwardly to overlap said outwardly projecting portion of the first plate when the door is closed.

If such an arrangement is fitted to a conventional door with rebated door frame, the presence of the two plates in close overlapping relationship can ensure that it is impossible for a flexible blade or sheet to be inserted between them and slid in as far as the bolt on the latch, owing to the convoluted path that is formed between the bolt and the exterior.

Preferably the portion of the second plate comprises a channel section in which the projecting front edge of the first plate enters as the door is closed. The second plate then so encloses the first plate that it would require an inserted flexible blade to bend around approximately 180 to pass between the plates, which still further reduces the possibility of it being inserted for enough to contact the bolt.

For mounting on a cylinder night latch the first plate can conveniently be formed with a mounting portion that has an aperture fitting the end of the cylinder projecting from the front face of the door and is secured by being clamped between the door and an escutcheon that surrounds the projecting end of the cylinder. This ensures that the first plate cannot be removed from the door except by removal of the escutcheon which conventionally is secured by bolts passing through the thickness of the door and which are inaccessible from the exterior.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a cross-section in a horizontal place of a door closure showing the first and second plates of the lock protection device in position on the door and its frame respectively, and Figure 2 and 3 are pairs of elevations of the first and second plates of the device in Figure.

Figure 1 shows the first and second plates 2, 4 of the protection device in position on a door 6 and its door frame 8 respectively. The door carries a night latch 10 with a spring-loaded bolt 12 that enters keeper 14 on the door frame to lock the door. The night latch comprises a lock cylinder 16 that extends through the thickness of the door 6 to its front face 18, where the end of the cylinder 16 projects and is surrounded by an escutcheon 20.

The first plate 2 is an L-section, limb 22 of which projects outwardly from the door 6 at right-angles to a main limb 24 which is secured against the front face, an aperture 26 in the main limb fitting closely the protuding lock cylinder. The aperture is shrouded and the plate is clamped in place by the escutcheon 20, which encircles the lock cylinder 16 and is secured to the door by bolts (not shown) passing through the door from the inside. The noncircular form of the aperture will be noted, the lobes 30 providing clearance for similar protuberances on the lock cylinder or the escutcheon bolts or their threaded housings, which thereby prevent rotation of the plate 2. The plate is thus positively and fixedly secured and cannot be released from the door without first gaining access to the interior.

The second plate 4 is a J-section, the main flat web 32 of which is attached to the door frame 8 to lie adjacent and parallel to the projecting portion 22 of plate 2. From the web 32 there extends a curved portion 34, in this example occupying an angle of nearly 1800. The curved portion 34 of the J-section plate is positioned to overlap and extend rearwards past the projecting limb 22 of plate 2 when the door is closed, as can be clearly seen from Figure 1. It is then not possible for a flexible strip or card of sufficient resilience to force the bolt to be fed around the gap between the two plates and the door and door frame because of the convoluted nature of the path to the followed.

The plate 4 is attached to the door frame by screws through holes 36 in the web and when the door is closed the heads of the screws are hidden by the limbs 22 of plate 2. This ensures that plate 4 cannot be removed unless the door is open. The arrangement of the two plates as seen in Figure 1 also shows that it would be extremely difficult to prise them apart, because the opening of the gap between them faces the door.

A further feature of illustrated arrangement is that it is relatively unobtrusive. In particular there are few projecting parts and these are relatively small, creating no obstruction.

Claims

1. A lock protection device for a night latch or other lock having a spring-loaded bolt, the device comprising a first plate having means by which it can be secured to the front or outer face of a door at the level of the lock and such that a part of the plate will project outwardly therefrom, adjacent the door frame, and a second plate having means for it to be secured to the door frame at the level of the first plate and comprising a part which extends inwardly to overlap said outwardly projecting portion of the first plate when the door is closed.

2. A device according to claim 1 wherein said overlapping part of the second plate comprises a channel section and the front edge of the outwardly projecting part of the first plate lies in the channel section when the door is closed.

3. A device according to claim 1 or claim 2, the first plate of the device having an aperture for receiving a lock cylinder of said lock, whereby the first plate is clamped between the front face of the door and an escutcheon that surrounds the front face of the cylinder.

4. A device according to any of the preceding claims wherein the means for securing the second plate to the door frame is covered by the outwardly projecting portion of the first plate when the door is closed.

5. A lock protection device substantially as described herein and as illustrated in the accompanying drawings.