GB2200681A

GB2200681A - Cover plate for cylinder rim lock

Info

Publication number: GB2200681A
Application number: GB08702452A
Authority: GB
Inventors: John Mcgill
Original assignee: Surelock McGill Ltd
Current assignee: Surelock McGill Ltd
Priority date: 1987-02-04
Filing date: 1987-02-04
Publication date: 1988-08-10
Also published as: GB8702452D0

Abstract

The cylinder rim lock has a key operable cylinder 1 with a connecting turn bar 3 for engaging a slot in a cam spindle for operating a latch bolt of the lock and a cam spindle cover plate 9 has a hole 11 for passage of connecting turn bar 3, the plate 9 incorporating a blind 12 pivotally mounted for obturating the hole 11 and spring 14 for biassing the blind 12 to obturate that hole should bar 3 be withdrawn. A spring detent 16 is optionally provided for securing the blind 12 in its obturating position. Cover plate 9 is shown recessed into door 1. The embodiment of Figure 3 shows a different arrangement from Figure 1 for securing of cylinder 1. Instead of the profiled bezel 7, a housing (17) and a locking ring (19) screwed onto a threaded rear section of the housing are utilised. <IMAGE>

Description

COVER PLATE FOR CYLINDER RIM LOCK This invention relates to a cam spindle cover plate for a cylinder rim lock assembly comprising a key operable cylinder equipped with a connecting turn bar for engaging a slot in a cam spindle for operating a latch bolt of the lock.

Cylinder rim locks are very well known, for example from British Patent No 762,243. and prior user of that and like designs.

Such locks comprise a key-operable cylinder which is to bse located within the thickness of a door or like closure and which has a connecting turn bar projecting into a slot in a cam spindle of the rim lock to be fitted to a rear face of the closure so that turning of the connecting bar effects movement of a latch bolt in the rim lock. The cylinder of such locks conventionally -has a front face portion which defines a flange, and two or more rearwardly directed threaded holes to receive machine screws for fixing purposes. For fixing the cylinder into the closure, it is conventional to provide a profiled front bezel which defines a recess for the front flange of the cylinder, and a back plate provided with holes. one allowing clearance for the connecting turn bar, and two for the machine screws used to fix the cylinder in place.The profiled front bezels most commonly available are pressed from sheet brass which is rather less than Imm in thickness, and the back plate is typically pressed from sheet steel about lmm thick. The size of such cylinders has become standardised, and to fix the cylinder in place. a hole one and one quarter inches in diameter (32mm) is drilled through the closure, the front flange of the cylinder is seated in the recess of the profiled bezel and the assembly is passed through the drilled hole so that the profiled bezel seats against the rim of the hole on the front face of the closure.The back plate is then passed over the connecting bar and presented to the rear face of the closure, whereafter two machine screws are screwed through the back plate into the threaded holes in the cylinder and tightened to clamp the front profiled bezel and back plate against the opposite faces of the closure and thus fix the cylinder into position.

There is a particular problem of security associated with this manner of fixing, in that it is a relatively easy, using a suitable lever, to prise the profiled front bezel and cylinder flange forwards and thus remove the cylinder from the closure by breaking the machine screws or dragging their heads through the back plate. It is then a simple matter to operate the latch bolt by inserting a screwdriver in the slot of the cam spindle of the rim lock and turning it.

It is an object of the present invention to provide improved security for such a rim lock.

According to this invention, there is provided. for a cylinder rim lock assembly comprising a key operable cylinder equipped with a connecting turn bar for engaging a slot in a cam spindle for operating a latch bolt of the lock, a c'jn spindle cover plate provided with a hole for passage and turning of such a connecting turn bar, said cover plate incorporating a pivotally mounted blind for obturating said hole and means for biassing the blind to obturate that hole.

In the event that the cylinder can be removed from the door or like closure, as the connecting turn bar is withdrawn through the hole in the cover plate, the blind will be pivoted across to obturate that hole thus preventing easy and immediate access to the slot in the cam spindle of a rim lock, so providing additional security.

The cover plate and blind are suitably made from steel. The steel may be plated, or a stainless steel if desired.

A preferred feature of the invention is that said cover plate further incorporates a detent for securing the blind in its obturating position.

The invention includes a cylinder rim lock assembly comprising a key operable cylinder equipped with a connecting turn bar for engaging a slot in a cam spindle for operating a latch bolt of the lock, characterised in that such assembly further includes a cover plate as herein defined.

It is preferred that said cover plate is of such shape and size that it can lie wholly within the area of that face of the lock which is to be fixed against a closure when its turn bar hole is in register with the cam spindle.

The invention also includes a door or like closure to which is secured a cylinder rim lock assembly as defined, wherein the cover plate is mounted to the rear face of the closure beneath the rim lock and with the blind facing towards the rim lock.

A preferred embodiment of the invention will now be described with reference to the accompanying diagrammatic drawings in which: Figure 1 is a partial cross sectional view of a rim lock cylinder fixed in a door, Figure 2 is an elevation of a cam spindle cover plate, and Figure 3 is a view corresponding to that of Figure 1 of an alternative rim lock cylinder installation.

In Figure 1 there is shown comprise a key-operable cylinder 1 of a rim lock (otherwise not shown) which is located within the thickness of a door or like closure 2 and which has a connecting turn bar 3 arranged for projection into a slot in a cam spindle of the rim lock to be fitted to a rear face of the closure so that turning of the connecting bar 3 effects movement of a latch bolt in the rim lock. The cylinder shown is of conventional form and has a front face portion which defines a flange 4. and two or more rearwardly directed threaded holes to receive machine screws 5,6 for fixing purposes. For fixing the cylinder into the closure, as is well known per se, there is provided a profiled front bezel 7 which defines a recess for the front flange 4 of the cylinder 1.

and a back plate 8 provided with holes, one allowing clearance for the connecting turn bar 3, and two for the machine screws 5,6 used to fix the cylinder in place. The profiled front bezels 7 most commonly available are pressed from sheet brass which is rather less than lmm in thickness, and the back plate 8 is typically pressed from sheet steel about lmm thick. The size of such cylinders has become standardised, and to fix the cylinder in place. a hole one and one quarter inches in diameter (32mm) is drilled through the closure, the front flange 4 of the cylinder is seated in the recess of the profiled bezel 7 and the assembly is passed through the drilled hole so that the profiled bezel seats against the rim of the hole on the front face of the closure.The back plate 8 is then passed over the connecting bar and presented to a rear face of the closure, whereafter two machine screws 5,6 are screwed through the back plate into the threaded holes in the cylinder and tightened to clamp the front profiled bezel and back plate against the opposite faces of the closure and thus fix the cylinder into position.

The slot in a cam spindle of a rim lock is then offered up to the connecting turn bar 3, and the rim lock (not shown as such) is then secured to the rear face of the closure, usually by means of wood screws.

In accordance with the present invention, improved security is afforded by the presence of a cam spindle cover plate.

A preferred embodiment of such a cam spindle cover plate is shown in section in Figure 1 and in elevation in Figure 2.

In the installation shown in Figure 1, the cover plate 9 is recessed into the rear face of the door 1.

As shown in Figure 2. the cam spindle cover plate 9 is rectangular in shape, and it is of such size that it will be hidden by the rim lock when the latter is fixed to the door. The cover plate 9 has holes at its corners for the location of fixing screws 10, and it also has a hole 11 for passage and clearance of the connecting turn bar 3.

The rear face of the cover plate 9 is provided with a blind 12 mounted on a pivot axle 13 so that it can swing to obturate the hole 11 under the bias of a spring 14 should the connecting turn bar 16 be withdrawn from the hole. A stop pin 15 is provided to prevent the spring 14 urging the blind 12 beyond the obturating position. One edge of the blind 12 is arcuate and bears against a spring detent 16 arranged to hold the blind 12 in its obturating position to prevent unauthorised access to the slot of the cam spindle of the rim lock from the front of the door. The cover plate is mounted to the door so that its blind 23 pivots downwardly into the obturating position. The weight of the blind thus acts as a supplementary bias.

Thus, in the event that the cylinder is removed from the door or like closure, as the connecting turn bar is withdrawn through the hole in the cover plate, the blind will be pivoted across to obturate that hole thus preventing easy and immediate access to the slot in the cam spindle of a rim lock.

An alternative rim lock cylinder installation is shown in Figure 3.

In Figure 3, the cylinder 1. instead of being secured to the door or like closure 2 by means of a profiled bezel 7 and back plate 8, is fixed into a housing which is in turn secured to the door. The housing 17 is held in place by pressure exerted on the front face of the door 2 by an integral front housing flange 18 and by a locking ring 19 screwed onto a threaded rear section of the housing 17. The locking ring 19 is located within a recess 20 cut into the rear face of the door 2. The locking ring 19 is circular and is provided with tommy holes 21 in order to facilitate tightening. In order to prevent the housing 17 from rotating while the locking ring 19 is being tightened. a key 22 is located in a hole drilled into the housing 17 behind the front flange 18, which key bears against the wall of a slot 23 out in the front face of the door.The slot 23 is hidden by the flange 18 when the housing is in place.

In order to fit the housing 17 to the door 2, recess 20 is first cut with an appropriate sized drill bit, the drill bit is replaced, and the hole 2 is then drilled through the door. The housing is then passed through the door from the front and the locking ring is tightened.

The rear of the housing 17 is closed by a wall 24 which is pierced by holes for the seating of machine screws 5.6 and by a hole 25 for the passage of the connecting turn bar 3 of the rim lock cylinder 1. The front flange 4 of the rim lock cylinder 1 seats in a closely fitting recess 26 machined in the front of the housing 17. The cylinder 1 may be secured into the housing 17 using the machine screws 5,6 either before or after the housing is fixed into the door.

The side wall of the housing 17 is preferably at least 4 mm thick.

It may for example be 6 to 7 mm thick.

The front flange 18 of the housing is bevelled, and preferably has a greatest thickness of at least 4 mm. Such thickness may for example be 8 to 9 mm.

The installation is equipped with a rim lock cover plate 9 as shown in Figure 2 and as previously described.

Claims

1. For a cylinder rim lock assembly comprising a key operable cylinder equipped with a connecting turn bar for engaging a slot in a cam spindle for operating a latch bolt of the lock. a cam spindle cover plate provided with a hole for passage and turning of such a connecting turn bar. said cover plate incorporating a pivotally mounted blind for obturating said hole and means for biassing the blind to obturate that hole.

2. A cover plate according to claim 1, wherein said cover plate further incorporates a detent for securing the blind in its obturating position.

3. A cylinder rim lock assembly comprising a key operable cylinder equipped with a connecting turn bar for engaging a slot in a cam spindle for operating a latch bolt of the lock, characterised in that such assembly further includes a cover plate according to claim 1 or 2.

4. A cylinder rim lock assembly according to claim 3, wherein said cover plate is of such shape and size that it can lie wholly within the area of that face of the lock which is to be fixed against a closure when its turn bar hole is in register with the cam spindle.

5. A door or like closure to which is secured a cylinder rim lock assembly according to claim 3 or 4, wherein the cover plate is mounted to the rear face of the closure beneath the rim lock and with the blind facing towards the rim lock.

6. A door or like closure according to claim 5, wherein the cover plate is so mounted that the blind pivots downwardly towards the obturating position.

7. A door or like closure according to claim 5 or 6. wherein the cover plate is recessed into the rear face of the door.