GB2269626A

GB2269626A - Security latch and automatic chain lock

Info

Publication number: GB2269626A
Application number: GB9217231A
Authority: GB
Inventors: Ian Lindsay Haye Mure
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-08-13
Filing date: 1992-08-13
Publication date: 1994-02-16
Also published as: GB9217231D0

Abstract

A security latch containing an automatic chain lock which is attached to the inside of a door which when closed guarantees the automatic engaging of the chain prior to the door locking. Partial rotation of door knob 18 lifts latch 13 enough to disengage edge 30 from retainer edge 29 yet still retain ball 11 and chain 7 which is attached to weight 8 so that the door will only partially open. Fully rotating knob 18 fully lifts latch 13 to release ball 11 and chain 7 allowing door to be opened. The security latch is connected to outer door face through a barrel lock, entrance being made with a key inserted into the barrel lock and rotated, one direction of rotation allowing partial opening of the door as ball 11 and chain 7 will still be retained by latch 13, opposite direction of rotation allowing normal entry. <IMAGE>

Description

SECURITY LATCH AND CHAIN LOCK This invention relates to a security latch with an automatic chain lock primarily for use on doors but can be used to secure any opening device which requires automatic restraint for security reasons after initial opening, as well as providing a secure automatic lock when closing the door. Both latch and chain lock can be released from the opposite face of the door to which it is attached. This invention allows for the automatic retention of the chain with a security latch thus providing for double security for a door on being closed, whether the occupant is staying in the house or leaving it.

There are a number of chain locks of varying descriptions in use but all require an extra operation, after closing the door, to apply the chain lock.

No chain lock device in current use can be released from the opposite face of the door to which it is attached.

According to the first aspect of this invention a horizontal 'U' shaped device, henceforth called a 'U' hook is so mounted that on closing the door it will automatically hook on to a ball to which is attached a chain and its weight.

The inner face of the 'U' hook contains a rising 45 degree ledge which has an angle of lift in the range between 20 degrees-90 degrees, preferably between 45 degrees-70 degrees, and more preferably is substantially 60 degrees.

The prime object of the ledge is initially to pick a ball up, to which is attached a chain, and raise the said ball to a position near the top of the 'U' hook.

The position of the ledge at the top of the 'U' hook being between lmm and lOmm from the top of the 'U' hook, preferably between 2 and 6mm and more preferably is substantially 3mm.

The ball diameter can be between lOmm and 50mm, -preferably between 15mm and 30mm and more preferably is substantially 25mm.

In all cases the major diameter of the 'U' hook must equal the ball diameter with the minor diameter of the hook being between 3 and 7mm and more-preferably 5mm smaller than the major diameter.

The weight of the mass attached to the chain must be sufficient to hold the ball securely in its retainer and must therefore be at least heavier than the ball by between 25%-200%, and preferably 40%-100%.

Alternatively the weight could be replaced with a tension spring which has an expansion of between 30 200mm, preferably 50-150mm and more preferably is substantially 75mm-lOOmm, but exerts a load which is always greater than the mass of the ball.

The 'U' hook which protrudes from the door edge is mounted to a base plate which is itself fixed to the door.

On closing the door the 'U' hook will pick up the ball which is held in a retainer mounted on the door frame. Having raised the ball from its retainer to the top of the 'U' hook it is now held in position with a spring loaded latch which has a swivel point at one end.

The latch contains a scalloped end so that the ball can rest neatly within the latch. The radius of the scallop matching that of the ball.

Beneath and behind the scallop the latch protrudes between 5mm and lOmm for a length of between 10 and 25mm in order to allow the latch to interlock with the ball retainer which also contains a raised tongue of similar height to the protruding lower edge of the latch, and having a similar length to the same protruding position of the latch.

The restraining spring of the latch may be of tension or compression type and will exert a load of between i to 2 Kgs and more preferably 1 to 14 Kgs.

The ball performs an important mechanical operation as well as providing the means for the automatic latching of the chain lock.

During the closure of the door the ball provides the cam action for the automatic raising of the latch to a position where it can automatically interlock with the retainer during its downward action. In order to aid this operation the latch carries a small chamfer of between 30 degrees and 60 degrees on its lower rear edge. Alternatively this chamfer can be replaced with a radius of between 6-lOmm.

The base plate in its centre carries a cam which is in contact with the latch. This cam provides the manual means for opening the door from either the inside or outside face.

To one end of the cam is attached an 'L' shaped or round handle, while the opposite end of the cam carries a slot which is used to locate a flat connector arm which is attached to the lock on the outer face of the door. The lock can be rotated by use of a key which in turn rotates the link arm and hence the cam into which it is inserted.

The cam is held under tension with a tension or compression spring and more preferably a tension spring which provides a load of between * Kg to 14 Kg and more preferably between i Kg to 1 Kg.

The cam is mounted between two bearings one mounted in the base plate and the other in the outside protective cover for the whole mechanism.

Where remote control may be required the cam could be rotated via an electric or pneumatic rotary actuator or alternatively the cam can be replaced with a linear solenoid actuator which can be pneumatically or electrically actuated.

Rotating the cam through about 20-30 degrees allows the latch to rise far enough for it to un hook from its retainer yet still retain the ball. The degree of rotation depending upon the lift angle of the cam and the depth of interlock between the latch and its retainer.

As the latch still has the ball in retention it will automatically pull the chain through the retainer until the weight attached to the chain comes into contact with the retainer and stops all further movement of the door, thus providing the security this device claims.

Rotation of the cam through 30 degrees to 120 degrees, or preferably 40 to 90 degrees or more preferably is substantially 60 degrees, will allow the latch to rise until it is in contact with the mechanism's cover at which point the ball is released from the 'U' hook. It is important to ensure that there is considerable movement during rotation of the cam between these two important release points to ensure that the door will always be initially opened on the chain and will not easily release the ball and chain.

For added safety the cam carries a check lever which will strike a check plate when rotated in a clockwise direction. The check plate being so positioned than only the interlocking action between the latch and its retainer is released. The cam is free to rotate in an anti-clockwise direction until the latch strikes the mechanism cover to release the ball.

This second check feature ensures the cam cannot be over rotated and will therefore always automatically return to its neutral position under the load exerted by both its own retention springs and the load exerted by the latch's retention spring.

A further additional safety feature which ensures that the latch cannot be raised by pulling the chain up in a vertical direction is the positioning of a restraining bar behind the latch which screws into the edge of the base plate and is further retained within the mechanism's cover.

To give additional strength to the mechanism the cam contains a slot which will retain the latch, while a further guide bar can be found on top of the U-hook through which the latch will slide, thus providing a solid sliding action for the latch.

In addition the cam can be provided with extra support from a lower support which protrudes from the base plate and which is so shaped that it carries a depression which equals part of the circumference of the cam in a radial manner.

Some embodiments of the invention will now be described by way of example with reference to the accompanying drawings of which, FIG 1. Shows in perspective the security latch and chain lock in operation with the door partially open.

FIG 2. Shows a side view of the mechanism which illustrates the latching mechanism which locks the door on closing, together with an activated alarm system and alternative tension spring to replace the weight if required.

FIG 3. Shows a front view of the complete mechanism as attached to the door.

FIG 4. Shows a plan view of the mechanism as attached to the door.

FIG 5. Shows an end on view of the mechanism, with the door ajar and retaining the ball and chain check mechanism.

FIG 6. Shows an end on view of the mechanism with the door closed, showing the latch interlock and ball retention, note the ball resting within the scalloped portion of the latch.

Referring to FIG 1. the latching mechanism is shown attached to base plate 15 which is screwed onto the door 1 via four wood screws 16.

The ball retaining mechanism 3 is screwed to door frame 2 via two wood screws 4.

FIG 1. shows the solid ball 10 resting in 'U' hook 12 and being retained with latch 13 which is held in position with spring 21 which is under tension, the spring is held in position via two spring retention pins one-of which 19 is attached to latch 13 and the other 20 being attached to the base plate. iS The restraining chain 7 is shown attached to ball 10, it passes under latch 13 and bar restraint 25 before falling through hole 6 found in the ball retainer 3. The chain is retained in the ball with spring pin 11. The other end of the chain is attached to weight 8 and held in position with spring pin 9.

To Release the ball cam 17 is rotated using handle 18 which locates in a slot 27 within the cam and is held in position via screw 26.

Rotation of cam 17 in either a clockwise or non clockwise direction will raise latch 13 in a vertical manner via swivel 14, until ball 10 is free to run down the guide rails 28 which are found inside 'U' hook 12.

Weight 8 is of sufficient mass to pull chain 7 through hole 6 in retainer 3 until ball 10 is resting on top of hole 6. The door is now free to open.

On closing the door the lower rear edge of latch 13 which has a suitable chamfer 30 which will strike the upper half of the ball 10 allowing latch 13 to rise as it follows the outer radius of ball 10. At the same time U-hook 12 picks up ball 10 from its retainer 3 at a point on the lower half of ball 10. The ball 10 is now raised up within U-hook 12 utilising the sloping guide rails 28 which are located within 'U'-hook's 12 inner face.

The guide rails 28 are designed to effectively lift ball 10 in a vertical motion as 'U' hook 12 moves in a horizontal motion. The net effect of this reaction is to ensure ball 10 has sufficient cam action to not only lift latch 13 over ball 10 but also to ensure the latch will carry far enough to interlock within slot 5 which is found in ball retainer 3.

When closing the door with ball 10 held in position within 'U'-hook 12 by latch 13, the latch will still rise automatically on contact with the retainer 3, by following the outer curve found on tongue 29 which forms part of slot 5 within retainer 3. Latch 13 has a similar radius at point 30 on its lower rear edge.

Spring 21 which keeps latch 13 in position is of sufficient strength to allow for a smooth rising of the latch through cam action from ball 10 or tongue 29 without having to slam the door, but the spring is so designed that the latch will always be firmly held in its down position at rest.

FIG 2 and 6 shows the interlock action between latch 13 and ball retainer 3. Latch 13 having come to rest in this position automatically from either following the outer curvature of ball 10 with its own interlocking tongue 31, or from following the radius found on the raised tongue 29 found on ball retainer 3.

The inner guide rail 28 is shown dotted within 'U' hook 12. This guide rail 28 is used to lift ball 10 from its rest position in ball retainer 3 to the top of 'U' hook 12.

Also shown is alarm contact 43 mounted close to or in contact with weight 8 which can swing freely is mounted within a guide tube 44 which is screwed to door frame 2 in order to stop it swinging and damaging the door frame or its surrounding area. The contact alarm 43 can be set for automatic or manual operation.

A time delay is incorporated within the automatic circuit to allow for normal entry, but where forced entry is used the time delay will come into operation to operate an alarm. This panel also incorporates a manual button or other activating device which can be operated by the householder where the intruder tries to force open the door after initial delatching and yet is still restrained by the chain.

Such manual operation setting off the alarm to alert other personnel within the vicinity that the householder is in trouble.

The other end of cam 17 locates within a bearing hole 36 found in cover 37 which locates over the complete mechanism and is held firmly in position through screw hole 38 which matches with the threaded hole 39 found in 'U' hook 12.

FIG 2. also shows next to the weight a tension spring which could replace the weight. The tension spring 46 being hooked onto chain 7 and anchored to door frame 2 via an anchored plate 47 and wood screws 48.

FIG 3. shows a front view of the latching mechanism attached to a door. 'U' hook 12 is shown extending from the edge of its mounting plate 15. The inner ledge 32 is shown as a dotted line, and it is this ledge that supports the ball. Cam 17 is shown in the centre of mounting plate 15 together with its rotating handle 18 and retaining screw 26. Latch 13 is shown with its pivot point and retainer 14. The latch sits within cam 17 through a slot to rest on the cam face this has the added feature of retaining the cam position within the bearing hole 34 found in mounting plate 15.

Latch 13 carries a radiused scallop at it's extreme end to allow ball 10 to rest properly within 'U' hook 12, also see FIG 5. Latch 13 is further sloped at its top edge 33 to allow it to open far enough to release ball 10, but is so designed as to strike the inner top face of cover 37 so as to stop over-rotation of cam 17.

The cam is held under tension for rotation in either clockwise or counter-clockwise direction.

Tension is applied via spring 23 which is held in position by spring pins 22 on 'U' hook and 24 on the cam for counter-clockwise rotation and by tension spring 35 which is held in position by spring pins 24 on cam and 20 in base support plate for clockwise rotation.

Latch 13 is held under tension through spring 21 which is retained through spring pin 19 mounted on the latch and spring pin 20 mounted on mounting base plate 15.

FIG 4. shows a plan view of the mechanism together with a key lock 49 mounted within the opposite face of door 1. The flat link bar 40 is shown linking key lock 49 to cam 17. This link bar 40 locates within slot 41 which is found within the centre of the rear face of cam 17.

Lock 49 can be any suitable key barrel lock which can be rotated with a key. For additional security this barrel lock can form an additional independent lock which would require opening prior to any movement of link arm 40 which when rotated will rotate cam 17 through a sufficient angle to not only release the latching mechanism between latch 13 and ball retainer 3 but will also release ball 10 to allow for full access through the door, see also FIG 6.

FIG 1 & 4.Bearing hole 34 for cam 17 is shown dotted within mounting plate 15 together with bearing shoulder 42 on cam 17 which locates in hole 36 within cover 37.

FIG 1 & 3.Strike arm 50 located in cam 17 is so positioned that on rotating cam 17 in a clockwise direction strike arm 50 will strike closure -12 so that latch 13 is released from the ball retainer yet still retains ball 10 which is attached to weight 8 via chain 7 thus ensuring that the door can only be partially opened as weight 8 is unable to pass through ball retainer 3.

Claims

1. Security apparatus comprising of two devices wherein: A first device is provided for mounting on a door or window to project from the edge thereof, A second device is provided for mounting on the frame of the said door or window at a location which, when the door or window is closed is adjacent said first device, One of said device comprising releasable catch means, closure means and rotating cam means and The other said device comprising retention and locking means which utilises an elongate weighted element provided with a latching member for automatic engagement with said catch means upon closure of the door or window from its fully open condition (in which said apparatus is disengaged), the releasable catch means being capable of only partial movement for unlocking from said locking means yet still retaining latching means with elongate weight element so that the door or window can only be partially opened as it is restrained by the elongate element, yet full movement of the releasable catch means will disengage the releasable catch means thus allowing for full opening of the door.

2. Apparatus according to Claim I wherein said first device comprises said releasable catch means, closure means and rotating cam means and said second device comprises said retention and locking means with said weighted elongate element.

3. Apparatus according to Claim 1 or 2 wherein said elongate element is flexible.

4. Apparatus according to Claim 3 where said elongate element comprises a chain.

5. Apparatus according to Claim 4 where said chain carries a weight.

6. Apparatus according to Claim 5 where said weight can be replaced with a tension spring which exerts a load similar to the load exerted by the weight.

7. Apparatus according to any preceding Claim wherein said releasable catch means comprises a closure member and means resiliently urging the closure member towards closure of the catch means.

8. Apparatus according to Claim 7, wherein at least one of said latching member and said closure member has a sloping surface at the location of their mutual engagement to facilitate entry of the latching member into the catch means by moving the closure member against the action of said resilient means and away from said closure of the catch means.

9. Apparatus according to Claim 7 or Claim 8, wherein said latching member comprises a substantially spherical surface at the location of mutual engagement of it and the closure member.

10. Apparatus according to any one of Claims 7 to 8, wherein said closure member is provided with a chamfered or bevelled or otherwise sloping surface at the location of mutual engagement between it and the latching member.

11. Apparatus according to any one of Claims 7 to 10, wherein said closure member comprises an elongate lever pivoted at a point distal from the region of its engagement of the latching member.

12. Apparatus according to Claim 11 wherein said elongate lever is held firmly in position with a spring attached between itself and the mounting plate to which its pivot point is also attached.

13. Apparatus according to Claim 9 wherein said latching member is primarily a solid ball.

14. Apparatus according to Claim 11 and 12, wherein said elongate lever has a protruding tongue at point of contact with said closure member.

15. Apparatus according to Claim 14 wherein said protruding tongue on elongate lever has a curved surface on its surface facing the catch and a vertical surface on its surface facing the cover for the complete apparatus.

16. Apparatus according to Claim 1 wherein the retention means comprises a protruding tongue containing a curved surface on its surface which faces the curve on the elongate lever, and a vertical surface on its surface that faces its fixing points.

17. Apparatus according to 11 and 12 wherein said elongate lever is held in a slot of a rotating member which is located between its pivot point and the closure member protruding from the same base plate.

18. Apparatus according to Claim 17 wherein said rotating member has two bearing surfaces one at each end together with a slot that mates with said elongate lever.

19. Apparatus according to Claim 18 wherein said bearing surfaces locate with one surface within the mounting plate and the other surface within the protective cover plate.

20. Apparatus according to Claims 17 to 19 wherein said rotating member carries a rectangular handle mounted within a slot which passes through the bearing surface that mates with the protective cover plate.

21. Apparatus according to Claims 17 to 20 wherein said rotating member is held under tension with 2 loaded springs mounted between a spring pin protruding vertically from its surface and one spring pin protruding vertically from the top surface of the closure member, and one mounted in the base plate.

22. Apparatus according to Claims 17 to 21 wherein said slot within rotating member which interlocks with the said elongate lever, has a radiused surface at the base of the slot so as to provide a smooth contact between said elongate lever and rotating member when said rotating member is rotated.

23. Apparatus according to Claim 22 where said curved surface within the rotating member is curved to form a cam so that on being rotated it will lift said elongate lever in a vertical plane.

24. Apparatus according to Claims 17 to 23 wherein said rotating member will always return to its neutral plane after its handle is released due to the downward load being exerted by the load carried on the elongate lever and the twisting tension load carried by the rotating member.

25. Apparatus according to Claims 17 to 24 wherein over-rotation is checked when the elongate lever comes into contact with the protective cover on the apparatus thus no longer allowing any further rotation, and also when the rotating member's restraining bar comes into contact with the closure member.

26. Apparatus according to any one of Claims 5 to 9, wherein the releasable catch means comprises a release member operable on said closure member.

27. Apparatus according to Claims 7 to 9, wherein said latching member with a spherical surface is a ball which is free to move but which is attached to the elongate member through a restraining member which contains the fixed protruding tongue.

28. Apparatus according to Claim 11, 12 and 13 to 17 wherein said elongate lever rises on contact with the spherical member of the latch as it moves up the sloping ledgered surface contained within the closure member, when the spherical surface has come to rest--at the top of the closure member the elongate lever falls behind the spherical surface following its course and coming to rest with the protruding tongue of the elongate lever interlocking with the protruding tongue on the fixed latching member.

29. Apparatus according to Claim 1 - 28 where said elongate lever is held in its rest and locked position utilising automatic applied load.

30. Apparatus according to Claim 1 to 29 wherein on rotating the rotating member through a short distance will release the elongate lever from its interlocking position with the fixed latching member, but it will still retain the spherical member attached to the flexible elongate member which passes through the fixed latching member.

31. Apparatus according to Claim 30 wherein the said elongate lever retains said spherical member within the said closure member as the two devices described in Claim 1 are pulled apart from each other until the said weight attached to the flexible elongate member has come into contact with the said fixed retaining member and can pull apart no further as said weight cannot pass through the said fixed member due to its diameter being larger than the hole found in the retaining member.

32. Apparatus according to Claim 1 to 31 wherein on rotating the rotating member considerably further will release the spherical member from the closure member where upon the spherical member is pulled down the sloping edges within the closure member by the weight acting at the end of the flexible member to which the spherical member is attached thus allowing for full opening of the door or window.

33. Apparatus according to Claim 17 to 25 wherein said rotating member carries a smaller slot at its centre within the surface at right angles to the bearing surface which inserts into the mounting plate.

34. Apparatus according to Claim 17 to 25 and 33 wherein said rotating member can be rotated via a handle mounted within the slot cut into the end of the end of the rotating member which protrudes through the cover of the apparatus.

35. Apparatus according to Claim 17 to 25 and 33 to 34, wherein sad rotating member can be rotated via the slot cut into the bearing surface which protrudes through the mounting plate of the apparatus.

36. Apparatus according to Claim 35 wherein a barrel lock can be connected to the said rotating member utilising a flat connector strip.

37. Apparatus according to Claim 35 and 36 wherein on rotating the barrel lock the said rotating member can be rotated via the flat connecting rod, thus freeing the elongate lever from its interlocking position with both its fixed retainer and spherical retainer, thus allowing the door or window to be opened.

38. Apparatus according to Claim 1 to 37 wherein there is an electrical fully insulated contact with the weight at the end of the elongate member.

39. Apparatus according to Claim 38 will allow an alarm to be triggered if so set when the weight moves away from its electrical contact.

40. Apparatus according to Claim 39 has a manual override switch which can be triggered by the operator on the inside of the door.