GB2149449A - Security latch mechanism - Google Patents

Abstract

The mechanism for a door has first and second retractable bolts 8, 17 for mounting on the inside of a door, and a safety stay 5 for mounting on a surrounding frame. The bolts are interengageable one, 8, behind an abutment 28 on the surrounding frame and one, 17, with the safety stay, e.g. chain 5 in the closed position of the door. The latching mechanism has two opening modes; a first mode in which both retractable bolts 8, 17 are disengaged so that the door can be opened normally from the outside, and a second mode, on opening the door from the inside in which only the bolt 8 engaging behind the abutment is disengaged. This means that the stay 5 is maintained in engagement with the other bolt limiting the opening of the door when opened from the inside. The bolt 17 may however be subsequently disengaged from the stay 5 without having to close or partially close the door. <IMAGE>

Description

SPECIFICATION Improved lock Tke present invention relates to an improved latching mechanism fora door and to a lock mechan- ism for a door including such a latching mechanism.

At present it is well known to provide a safety chain on a doorto allow partial opening of the door without permitting access. However, in known arrangements the chain has to be deliberately engaged with the door, the door opened to see who is there, and then the door has to be closed again to allow release ofthe chain before the door can be fully opened. Thus, known arrangements require a positive decision to engage the safety chain as well as the need to close the door before full opening. In some instances the engaging ofthe safety chain may be inadvertently overlooked which could allow access to an intruder: old people are particularly vulnerable in this respect.

In another known arrangement disclosed in U.K.

Patent Specification No. 1516093 there is disclosed a security device which can take a safety chain with the door when opening the doorfrom the inside. Howev er, that arrangement has two disadvantages: firstly, in the closed position the door latch is not engaged with the safety chain, this can be effected on opening. However, the latching of the safety chain could be by-passed if the door were opened quickly, for example, in a forcible entry and secondly,thelatching ofthesafetychain isa matter of choice determined buy a manually operated peg so thatthe safety chain will only be engaged when the peg is in one of two positions.

According to the present invention there is provided a latching mechanism for a door comprising a retractable bolt means for mounting on the inside of a door, and a safety stayfor mounting on a surrounding frame, the bolt means being interengageable behind an abutment, on orforfitting on, the surrounding frame and with the safety stay in the closed position of the door, the retractable bolt means having two opening modes, a first mode in which the retractable bolt means is disengaged from behind the abutment on the surrounding frame and from the safety stay so that the door can be opened from the outside, and a second mode in which the retractable bolt means limiting the opening ofthe door.

The safety stay may be a safety chain or bar.

Preferably the retractable bolt means comprises first and second retractable bolt members, one for engaging behind the said abutment and one for engaging with the stay which may be released by manipulation of an operating lever. In the preferredembodimentthe first and second retractable bolt members cannot be retracted together thereby making it impossible to open the door with the safety stay in position.

According to the preferred embodiment of the invention, a latching mechanism for a door comprises afirstretractableboltmemberformounting on the inside of the doorfor interengagement behind an abutment on, orforfitting on, a surrounding door frame, a safety stay for mounting on the surround frame, a second retractable bolt memberfor mounting on the inside of the doorfor interengagement with the safety stay, first release means on the inside of the doorfor retracting the first retractable bolt member, second release means on the inside ofthe doorfor retracting the second retractable bolt member, said first and second release means being prevented from simultaneous operation, and interlocking means for simultaneous retraction of both the first and second bolt members from the outside of the door when the door is opened with a key, the arrangement being such that, when the door is opened from the outside it may be opened normally, but when the door is opened from the inside by manipulation of the first release means onlythe first bolt member is retracted whilst the second bolt member is prevented from retraction and remains in engagement with the safety stay allowing opening ofthe door only to a position limited by the length ofthe safety stay, full opening of the door being possible by release of the first release means and manipulation of the second release means to release the second bolt memberfrom the safety stay so that the door may be fully opened without first closing itto release the safety stay. Preferably the safety stay is a chain spring-biassed to its unextended position.

The invention will new be described by way of example with reference to the accompanying drawing in which: Figure 1 is an exploded front elevation of a lock mechanism in accordance with the present invention; Figure 2 is a side elevation of a door showing the lock mechanism in position; Figure 3 is a view ofthe latch portion of the lock mechanism on the inside ofthe door in the direction of arrowAin Figure 2; Figure 4 is a diagrammatic section on 4-4 in Figure 3; Figure 5 is a plan viewofthe interlocking memberof the present invention; Figure6 isa view on arrow B in Figure 5; Figure 7 is a view on arrow C in Figure 1 with the chain in; Figure 8 is a view on arrows in Figure 1 with the chain out; Figure 9 illustrates a modified arrangementwhere the chain is replaced by a safety bar;; Figure loins an exploded perspective view ofthe preferred embodiment; Figure 11 is a plan view showing the latching arrangement in engagement with a door frame; and Figure 12 is a plan view with the door open and the chain engaged.

In the drawings a lock mechanism 1 comprises a lock 2 accessible from the outside of a door 3, a latch portion 4 on the inside of the door aligned with the lock 2, and a safety chain 5 secured to the door frame 40 (figures 11 and 12).

The lock 2 may be of conventional design and forms no partofthis invention, accordingly no details are contained herein Preferably, however, the lock 2 is a cylinder lock having a central, rotatably mounted cylinder which, in the locked position, is prevented from rotating buy a numberofspring-biassed pin tumblers. When the correct keyforthe lock is inserted into the lock 2 the pin tumblers are raised to the position in which the cylinder is free to rotate and therebyturn a semi-circular cam 6 on the inside ofthe door3which is operable to release the latch.

The latch portion 4 has a first retractable bolt member 8 which has a rearwardly extending yoke 38 connected thereto with offsetinnerandoutershoul- ders 9 and 10 at the free end thereof. The inner shoulder9 abutsthe diametriccontourof a cam 11 connected to an opening knob 12 on the inside ofthe door3.Theoutershouldersl0are rearwardly displacedfromthe innershoulders 9 so asto receive an interlocking member 13, also of yoke form, which lies against the yoke 38 and has outer shoulders 14the rearward abutmentsurfaces of which abutthe shoulders 10 and the forward abutmentsurfaces of which are aligned with the abutment surfaces ofthe inner shoulders 9.The abutment shoulders 14 cooperate with the diametric contour of the cam 6 connected to the lock 2. The shoulders 10 on the yoke 38 and the shoulders 14 on the member 13 are provided with clearances as shown to permit the rotation ofthe respective cam 11 and 6. The interlocking member 13 also has an upstanding spacer 15 preventing lateral movement and an inner interlocking extension 16 as will be explained.

In addition to the main retractable bolt member 8 the latch portion 4 of the lock mechanism 1 of the invention also has a second retractable bolt member 17 which extends rightthrough the casing 18 ofthe latch portion4andterminatesin acurved grip 19.

Intermediate its ends the second retractable bolt member 17 has an elongate recess 20 which receives the inner interlocking extension 16 ofthe interlocking member 13 although the recess 20 is longerthan the extension 16. The first and second retractable bolt members 8 and 17 are spring-biassed to theirforward opposition by respective springs 21 and 22 as shown.

In orderto preventthefirst and second bolt members 8 and l7frombeingoperatedsimul- taneously a lever 42 is pivoted to the casing 18 at 42.

The lever41 hasa curved bulbous head 43 atitsfree end which is aligned with and cooperates with a slot 44 in the bolt member 17. In addition a stop 45 is provided on the inside ofthe casing 18so thatthe cam 11 can be rotated in one direction only.

The safety chain 5 shown in Figures 1,7,8,10,11 and 12 is received on an elongate support 23 and has a tubular connector 24 atthefree end thereof which, in its position of rest, is aligned with and receives the head of the second retractable bolt member 17, and a movable stop 25 is connected to spring 26 and cooperates with a fixed stop 27 on the support 23 so thatthe chain 5 is spring-biassed to the position shown in Figures 1 and 7. Located just above the tubular connector 24 is an aperture 28 into which the first retractable bolt member 8 extends when the door is closed.

Positioned on the inside ofthe latch portion 7 ofthe lock mechanism 1 ofthe present invention is a bracket 29 which, when the door has been closed such thatthe second bolt member 17 is received in the tubular connector24, prevents separation ofthe two without retraction ofths second bolt member 17. When the door is closed the bracket 29 lies behind the support 23 as indicated in dotted lines in Figure 1; the two portions being separated for clarity.

In the arrangement of Figure 9 the safety chain is replaced by a solid stay in the form of a hooked bar 51 which is pivoted at 52 to a fixture 53 on the doorframe.

In use, if the door 3 is being opened from the outside with the correct key, the cam 6 is turned which, via engagementwith theouterabutmentshoulders 14On the interlocking member 13 moves the interlocking member 13 rearwardly. This rearward movement retracts the first bolt member 8 through the interaction ofthe interlocking member 13 with the outer abut ment shoulders 10 on the yoke 38 and retractsthe second boltmember 17through the interengagement ofthe inner interlocking extension 16 on the interlock ing member 13 and the elongate recess 20 in the bolt member 17: the bulbous head 43 of the lever 41 riding out oftheslot44. Thus, from the outside, the door opens normally.

On the inside, on operating the door 3 with the knob 12,the cam 11 is turned which, through the interengagementwith the inner shoulders 9, moves the yoke 38 rearwardly thereby retracting the first bolt member 8. However, because there is no corresponding interengagement between the yoke 38 and the interlocking member 13, the yoke 38 moves rearwardly relative to the interlocking member 13 leaving the second bolt member 17 positioned within thetubular connector 24 of the chain. Moreover, the turning of the cam 11 causes an extension 46thereon to push the head 43 of the lever41 firmly into the slot 44 thereby positively preventing simultaneous retraction ofthe second bolt member 17.Thus, when the door is actually opened,the chain 5 is drawn out bytwo or three inches as shown in Figure 8 and 12 until the movable stop 25 engages the fixed stop 27. This enables the person opening the door 3 to open it sufficiently farto see who is outside whilst maintaining positive engagement between the second bolt 17 and the chain 5. Only if it is desired to then open the doorfurther is the bolt member 17 positively moved rearwardly by release ofthe knob 12 and by manipulation ofthe grip 19to release the bolt member 17 from the tubular connector 24. This is permitted without movement ofthe interlocking member 13 by the recess 20 being longer than the interlocking extension 16.Whilst the second bolt member 17 and the tubular connector 24 are still engaged, the bracket 29 prevents the tubular connector 24 being pulled offthe end ofthe second bolt member 17 by a potential intruder. If desired the bolt member 8 and 17 may have a conventional meansforlockingthem in the retracted or extended modes.

Where a safety stay bar 51 is used, the bolt 17 engages behind the bar 51 and, from the inside, provides automatic latching with the bar 1 to allow opening of the door only until the bolt 17 engages with the hook. In order to open the door completely, the second bolt 17 must be retracted, as described above, to disengage itfrom the bar 51. With this arrangement, instead ofthe bracket 29, means would be provided to prevent the bar 51 being pivoted away from the bolt 17 to prevent a potential intruder gaining access.

Claims (9)

1. A latching mechanism for a door comprising a retractable bolt means for mounting on the inside of a door, and a safety stay for mounting on a surrounding frame, the bolt means being interengageable behind an abutment on, orforfitting on, the surrounding frame and with the safety stay in the closed position of the door, the retractable bolt means having two opening modes, a first mode in which the retractable boltmeans is disengaged from behind the abutment on the surrounding frame and from the safety stay so thatthe door can be opened from the outside, and a second mode in which the retractable bolt means is disengaged onlyfrom behind the abutment so that, on opening the doorfrom the inside, the stay is main tainedin engagement with the retractable bolt means limitingtheopening of the door.

2. Alatching mechanism according to claim 1 whereinthe safety stay is a safety chain.

3. A latching mechanism according to claims 1 or 2 wherein-the retractable bolt means comprises first and second retractable bolt members, one for engag- ing behindthesaid abutment and one for engaging with the staywhich may be released by manipulation of an operating lever.

4. A latching mechanism according to claim 3 wherein the first and second retractable bolt members cannot be retracted togetherthereby making it impossible to open the doorwithoutthe safety stay on position.

5. A latching mechanism according to claim 4 including a leverwhich cooperates with the retractable bolt member and which, in use, is held againstthe second retractable bolt member to prevent retraction thereof when the first retractable bolt member is retracted.

6. A latching mechanism for a door comprising a first retractable bolt memberfor mounting on the inside of the doorfor interengagement behind an abutment on, orforfitting on, a surrounding door frame, a safetystayformounting on the surrounding frame, a second retractable bolt member for mounting on the insideofthe doorfor interengagementwith the safety stay, first release means on the inside of the doorforretractingthefirstretractable bolt member, second;;rerease means on the inside ofthe doorfor retracting the second retractable bolt member, said first and second release means being prevented from simultaneous operation, and interlocking means for simultaneous retraction of both the first and second bolt members from the outside of the door when the door isopened with a key, the arrangement being such that, when the door is opened from the outside it may he opened normally, but when the door is opened fromthe inside by manipulation ofthefirst release means only the first bolt member is retracted whilst the second bolt member is prevented from retraction andremains in engagement with the safety stay allowing opening ofthe door only to a position limited bvthelength ofthesafetystay,full opening of the door being possible by release ofthe first release means and manipulation of the second release means to release the second bolt member from the safety stay so thatthe door may be fully opened without first closing itto release the safety stay.

7. A latching mechanism according to claim 6 wherein the safety stay is a safety chain springbiassed to its unextended position.

8. A locking mechanism having a lock and a cooperable latching mechanism according to any one ofthe preceding claims.

9. A latching mechanism substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.