AU627372B2

AU627372B2 - Improved latch

Info

Publication number: AU627372B2
Application number: AU65581/90A
Authority: AU
Inventors: Gunther Sprekeler
Original assignee: Whitco Pty Ltd
Current assignee: Whitco Pty Ltd
Priority date: 1989-10-30
Filing date: 1990-10-30
Publication date: 1992-08-20
Anticipated expiration: 2010-10-30
Also published as: AU6558190A

Description

v 627372 COMMONWEALTH OF AUSTRALIA The Patents Act 1952-1969 Name of Applicant WHITCO PTY LTD.

0 000000 0 00 0 0 *0 00 00 0 000 0 i~* 0 0 000 0 .0 SO 0 '6000 Aaarcess of Applicant(s) 4 50 Sherwood Road, SHERWOOD QUEENSLAND 4075, AUSTRALIA Ac-tual, Inventor(s) Acdaress for Service% CULLEN CO., Patent Trade Mark Attorneys, 240 Queen Street, Brisbane, Qid. 4000, Australia.

0000 0 0000 0.00 0 00 00 0 0000 0 0 0000 000000 0 0 60 ~j 0 0 0000 00 00 00 0 0 COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED; IMPROVED LATCH The following statement is a full description of the invention including the best method of performing it known to us

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THIS INVENTION is directed to an improved latch and is particularly directed, although not limited to, an improved latch for security screen doors and the like.

Security screen doors have become a popular means of deterring would-be intruders. Security screen doors generally comprise a hollow box-like extruded aluminium peripheral frame and a sturdy screen of metal mesh or cast decorative panels within the frame.

One disadvantage with such security doors is that they possess an inherently flexible nature. Although one e• side of the door frame may be rigidly supported towards the upper middle and lower regions by hinges, the opposed, side is supported only in the middle region by a lock. It has been found that these screen doors can be opened by levering the upper and/or lower door frame portions outwardly, thus bending the frame in the region of the lock. This results in the tongue of the lock being able to be levered out of a slot in a striker thereby allowing the screen door to be opened.

In one other earlier proposal a multi point locking e« 0 system was provided. In that system there was a main latch tongue which projected from a edge of the door and two auxiliary bolts, one auxiliary bolt, in the locked position, would extend through an aperture in the head of the door frame and the other would extend through an aperture in the floor. With such systems there was a tendency for the aperture in the floor to become filled with dirt and other objects and thus the system was sc mctiii'es difficult to use in I-~--~IIIILILIIIIIII11111 I I n 3 One' attempt at improving such an arrangement is to provide a lock in the middle region of a security screen door and a remotely located latch member. Operation of the central lock operates the remote latch member. Such an arrangement is disclosed in Australian Patent Application 30549/84.

A similar lock is disclosed in the applicant's earlier Patent 574388 which includes a central deadlocking lock and a pair of remotely positioned latches.

A disadvantage with the abovementioned locks is that the remo:ely positioned latches are not of the deadlocking type. Thus, an intruder is able to manipulate the latch tongue of the remotely positioned latches to force the latch tongue back into the main body. This then allows the security door to be forced in the manner described above by levering 5 the upper and/or lower door frame portions outwardly, thus bending the frame in the region of the main lock.

4 SIt is an object of the invention to provide an improved latch for a security screen door which at least partially overcomes the abovementioned disadvantages.

.2p In one form the invention resides in a latch for a security screen door the latch including a body; a latch tongue slidably mounted in said body for movement between an extended position and a retracted position; and an operating member pivotally movable between a first position where the latch tongue is extended and a second position where the latch tongue is retracted, the operating member having a first arm operatively connected to the latch tongue and a second arm

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v -I 4 F operatively connected to an actuating member for actuating the operating member, the first arm when in the first position adopting an over centre position and therefore being unable to return to its second position by attempted depression of the latch tongue thereby deadlocking the latch tongue in its extended position.

The latch may be mounted to a security screen door or other type of door at a position spaced from the conventional central lock and door handle. Preferably the latch is located at the top and/or bottom portion of the door.

The door preferably contains two latches one mounted to the top portion and the other to the bottom portion of the door.

The latch may be mounted such that the latch tongue engages with the side, top or bottom portions of the door frame.

The latch may be operably connected to the central S alook such that operation of the central lock operates the or each latch. Alternatively, the or each latch may be operated separately from the central lock.

The body is suitably made by die casting although 2t this is not necessary. The body may include side walls and a top and bottom wall and a rear wall to define a chamber into which the latch tongue can be retracted. One side wall may be provided by a removably fixed cover plate to the body by suitable fixing members such as screws. The body may include mounting extensions. The extensions facilitate attachment of the latch to a door or the like. The extensions may extend outwardly from opposed walls of the body, The extensions may

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A have apertures to allow fixing members to secure the latch to a door.

The latch tongue is suitably formed from die cast material. The tongue may be of a substantially rectangular configuration having opposed side faces. One or both of the side faces may be tapered to provide a nose portion. Each side face may also include a ribbed portion extending part way along the side face. The ribbed portion may be designed to catch the edge of the aperture in the striker if the latch t.6' tongue is forced by an intruder. The latch tongue may be a.

S biassed into its extended position by biassing means such as t a spring. austfralian patent appnli catin P.T 11 .i relate.-. ton latch tongue having gr 2e- or serrations on side faces theen w made by th present faplicant.---- The operating member may be pivotally mounted to the body. The operating member may comprise a lever having a pair of arms defining an angle therebetween, the apex portion of the lever formed by the two arms being pivotally mounted to the body. One of the arms may be operatively connected to .OQ the latch tongue while the other of the arms may be operatively connected or connectable to an actuating member.

Actuation of the actuating member may pivot the operating member which in turn moves the latch tongue between the extended and retracted positions.

When the latch tongue is in the extended position, the arm of the operative member which is operatively connected to the latch tongue can adopt a position such that 6 the latch tongue is prohibited from moving from its extended position to the retracted position. Retractioni of the latch tongue may only be possible upon initial pivotal movement of the operating member away from its prohibiting position.

The invention shall be better understood by reference to a preferred embodiment thereof as illustrated in the accompanying drawings in which:- FIG 1 is an exploded view of a latch tongue according to the invention.

e *i S1*i. FIG 2 is a side elevation view of the latch tongue of FIG 1.

The latch 10 comprises a body 11, a latch tongue 12, and an operating member 13. Body 11 is die cast and has a peripheral wall 14 which provides a top, bottom and rear wall, a side wall 15, and a second side wall 29 which is formed separately from body 11 and securable thereto through S screws, rivets or the like. The front of the body has integrally formed mounting extensions 16 formed with apertures for allowing fixing members such as screws or rivets to pass through the apertures to fix the extensions to 0 a door or like member. The two side walls 15, 29 of body 11 when assembled define a chamber in which latch tongue 12 can slide.

Latch tongue 12 is also of a die cast material and is of a generally rectangular configuration. The latch tongue has two opposed side walls 17, 18 which have a ramped or tapered portion 19 at their forward end to provide the 7 provided on both side faces 17, 18 (only one face shown) behind ramped face 19. The ribbed portion extends vertically across each side face and acts to engage against the edge of the stri'er aperture should latch tongue 12 be forced by an intruder.

One rear corner of latch tongue 12 has a cut away portion and an arcuate slot 21 is provided in the floor of the cut away portion. The arcuate slot 21 is substantially L 5* shaped and includes a first and second channel and an edge.

.o 0 t The operating member comprises a substantially L g.

S S 0 shaped lever having a first arm 22 and second arm 23. At the apex of arms 22 and 23 there is an aperture 24 about which the operating member pivots. The operating member pivots about pivot pin 25 which is integrally formed on body 11 Arm 22 is provided at its distal end with a pin 26 which is 000 configured to be received within arcuate slot 21.

FIG 2 shows the assembled latch with the latch S00,'29 tongue 12 in the extended position. In this position pin 26 on arm 22 is located at one end of arcuate slot 21. In this configuration, the operating member 13 is in an over centre position and to one side of edge 30 of the slot 21 and therefore latch tongue 12 cannot be moved from its extended position by simply forcing the tongue into the body due to abutment of pin 26 against the wall of arcuate slot 21 and the presence of edge j.

8 The other arm 23 of operating member 13 is provided with a bore 27 into which can be fixed an end of an actuating member such as a rod, shaft or chain (not shown). Movement of the actuating member will pivotally move operating member 13 which in turn moves pin 26 from one end of arcuate slot 21, past edge 30 and to the other end of the slot. As depicted in FIG 2, pin 26 is in an over centre position and prevents latch tongue 12 from retracting. Upon pivotal movement of operating member 13, pin 26 travels through arcuate slots from the end depicted in FIG 2 to the other end 28 which moves pin 26 away from its over centre position.

Movement of pin 26 through arcuate slot 21 causes latch S tongue 12 to retract within body 11. Obviously, pivotal movement of operating member 13 in the opposite direction 15 will cause pin 26 to travel from position 28 back to the position illustrated in FIG 2.

*9 The actuating member (not shown) may be a rod linked to the central lock of the screen door such that operation of the bolt of the central lock also operated latch tongue 19 by virtue of the actuating member pivoting operating member 13. In use, two latches like that discussed would be used in conjunction with a central lock of the screen door. One of the latches would be located above the central lock and the other below the central lock. The latches and the central lock are arranged such that the respective latch tongues normally extend outwardly through an adge of the door when in the extended position.

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9 Thus, when the latch as described in the above embodiment is in the latched position, i.e. when latch tongue t is in the extended position, latch tongue cannot readily be forced into its retracted position.

It should he realised that various other changes and modifications may be made to the embodiment described without departing from the spirit and scope of the invention.

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Claims

1. A latch for a security screen door the latch including a body; a lat /h tongue slidably mounted in said body for movement between an extended position and a retracted position; and an operating member pivotally movable between a first position where the latch tongue is extended and a second position where the latch tongue is retracted, the operating member having a first arm operatively connected to the latch tongue and a second arm operatively connected to an actuating member for actuating the operating member, the first arm when in the first position adopting an over centre position and therefore being unable to return to its second position by attempted depression of the latch tongue thereby deadlocking the latch tongue in its extended position.

2. The latch as -laimed in claim 1, wherein said first arm and said second arm define an angle therebetween and include an apex portion, said operating member being pivotally mounted to said body at said apex portion.

3. The latch as claimed in any one of the preceding claims, wherein said latch tongue includes a slot disposed adjacent a rear portion of the latch tongue, said operating member being operatively connected to the latch tongue through said slot.

4, The latch as claimed in claim 3, wherein said slot is substantially L shaped in configuration and includes a first channel extending generally towards a front portion of the latch tongue and a second channel extending generally towards an upper portion of the latch tongue, said first and i. 2 as second channels defining an edge adjacent their proximal ends.

The latch as claimed in claims 3 or 4, wherein said first arm is provided adjacent its free end with a pin which is configured to be received within said slot.

6. The latch as claimed in cI,-Uv,, 5, wherein actuation of said operating member to its first-position to move said latch tongue to its extended position causes said pin to move along a portion of said slot and to locate adjacent the free end of said first channel, and said operatingmember is caused to adopt an over centre position thereby deadlocking said latch tongue.

7. The latch as claimed in claim, 6, wherein actuation of said operating member to its second position to move said latch tongue to its retracted position causes said pin to mo-vo from the first channel over the edge and along said second channel whereby the latch tongue is undeadlocked.

8. A door comprising a. central lock and one or more latches as claimed in any one of the preceding claims, said latches being mounted to said door remote from said central look and operatively connected to the central lock such that operation of the bolt of the central lock actuates the operating member of said one or more latches to r0a,-Cact or extend said latch tongue.

9. A latch substantially as hereinbeforG described with reference to the accompanying drawings. D- TED this Twentysixth day of May 1992. WHITCO PTY LTD by their Patent Attorneys CULLEN CO.