AU2006200379A1 - Lock with tongue and striker plate assembly - Google Patents

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

Name of Applicant: EGRESS AUSTRALIA PTY. LTD.

Actual Inventor(s): DARREN MICHAEL PULEIO Address for Service: SANDERCOCK COWIE SUITE 8C, 50-54 ROBINSON STREET DANDENONG VIC 3175 Invention Title: LOCK WITH TONGUE AND STRIKER PLATE ASSEMBLY Details of Associated Provisional Application(s): No(s): Australian Provisional Application No. 2005900339 Filed: 2 7 th January, 2005 The following statement is a full description of this invention, including the best method of performing it known to us: 1 Fc2006-I -27,Z:\Filingegfess. file. pd, I -la- TITLE: LOCK WITH TONGUE AND STRIKER PLATE ASSEMBLY FIELD OF THE INVENTION This invention concerns locks for security doors, such locks may have with tongues and striker plates which are modified to resist a prying force on the door which intruders exert in an attempt to spring the lock tongue from the striker plate.

2006-0i-27,Z:\Specifications\egress.capwpd, I BACKGROUND OF THE INVENTION Night latches may be opened by unauthorised persons by sliding a plate or blade against the curved face or the tongue in order to move it clear of the striker plate. This mode of entry has been defeated by introduction of a groove cut in the face of the tongue so that pressure on the blade would not result in sliding motion of the tongue. In practice, the striker plate sometimes had an edge which engaged the groove but often did not, so the locks were prone to failure by the exertion of prying force. The purpose of the groove was to prevent unauthorised opening by use of an inserted blade. The lodging of the same groove in the striker plate during prying was unintentional but useful to the householder in that it made unauthorised entry more difficult.

AU616068 concerns locks for security doors and discloses the provision firstly of serrations on the opposed side faces of the lock tongue and secondly a striker plate with an aperture and an edge which could arrest the serrated tongue if the door were forced with ajemmy. The effect of the insertion of ajemmy between the door and its frame by an intruder outside the door is to push the door against the frame rebate.

Pushing the door in this way moves the lock tongue serrations into engagement with the projecting edge of the striker plate. This cooperation is intended to resist further movement thereby neutralising the attack.

In practice, such serrations fail to meet the tests applied by the appropriate authorities who require that the lock resists opening for a specified period.

The serrations may fail to lodge in the striker plate for various reasons. Each door and frame are slightly different in clearance. The door hinges permit different range of movement. Atmospheric dampness or dryness alters the dimensions of wooden components. The alignment of a lock in the door may favour arrest from one direction but not in the opposite direction. The lock must resist attack from an intruder trying to gain entry from outside so to resist attack from outside, engagement of the lock with the striker plate edge must be inevitable.

2006-01 -27,Z:\Specificatiops\egress.cp. wpd,2 In our co-pending application for Patent No. 2004203232, we describe a lock for a security door which has a lock of the type which can be locked from the outside but opened from the inside. Such locks are vulnerable to being forced because security doors are commonly of lighter construction than solid external doors.

SUMMARY OF THE INVENTION One apparatus aspect of the invention provides a lock assembly having a lock tongue and striker plate, the tongue having two or more side by side grooves in at least the inside face of the tongue directed normally to the latch tongue motion and the striker plate having an aperture which allows to and fro motion of the tongue and a tab projecting from the inside edge, the aperture allowing to and fro motion of the tongue for lock operation but the application of prying force causes the tab to enter the groove preventing tongue withdrawal.

The grooves may be of rectangular section.

More specifically the invention provides a lock and striker plate assembly comprising a lock with a latch tongue having opposed faces for insertion through an aperture in a striker plate, one or both faces having at least two side by side grooves extending at least across the mid portion of the face, wherein the grooves are mutually separated one from the next adjacent groove by an intermediate margin in order that the tongue face may slide to and fro in the aperture past the striker plate, wherein adjacent grooves are mutually separated by intermediate margins of the face of the tongue, and a striker plate having an aperture for the tongue defined by a pair of opposed edges separated sufficiently to allow the opposed faces of a latch tongue to pass between the edges, at least one edge having a projection capable of entering a groove and obstructing the withdrawal of the tongue.

BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of the invention is now described with reference to the accompanying 2006-01-27,Z:S pecification sress.cap.wpd,3 -4drawings, in which: Figure 1 is a side view of the tongue.

Figure 2 is a plan of the tongue.

Figure 3 is a perspective view of the tongue.

Figure 4 is a plan of the striker plate.

DETAILED DESCRIPTION WITH RESPECT TO THE DRAWINGS In our co-pending Application No. 2004203232, we describe a security door lock of which the tongue and striker plate are components. That document explains the manner of operation of the tongue and the reason for the slope of the tongue shown in Figures 1- 3. This description is therefore confined to the tongue and striker plate.

Referring now to Figure 1, the foremost part of the tongue 2 is the part which enters the cavity of the door indicated by broken lines. In practice, the separation between the door accommodating the lock and the frame which accommodates the striker may vary by reducing the projection into the aperture.

Accordingly, the flat face 6 of the zinc die-cast tongue has three side by side grooves 8, 12 in the central field of the face. Each groove is 3mm wide, 1mm deep and long. The grooves are situated at 5mm centres and the foremost groove 8 has a centre line disposed parallel to and 7mm away from the nose 14 of the tongue. Consequently about 50% of the tongue face area consists of grooves.

In Figures 2 and 3 the dispositions of the grooves in both faces are evident. The tongue is 10.5mm thick and is intended to shoot into the cavity 16 making at least two grooves invisible within the aperture.

Referring now to Figure 4, the cavity of Figure 2 must be sufficiently deep to allow at 2006-01 27,Z:Specificatios\egress.cap. wpd4 least two grooves to move past the striker plate upon locking by the operator.

The steel striker plate has a conventional curved striker 18 and screw holes 20. The substantially rectangular aperture 22 has two longer edges 24 lying 15mm apart. Each has a central raised step 26, 28, 14mm long and 1.5mm high, projecting into the path of the tongue. The depth of the aperture is 34mm, some 4.5mm deeper than the depth of the tongue.

Step 28 will flex if the door is forced.

In use the tongue will pass between the steps with 1.5mm clearance on each face.

Grooves are provided in both faces of the tongue but in use the face of the tongue closest to the door rebate will be arrested. As soon as the intruder moves the door 2mm closer to the door rebate, step 28 engages one of the grooves 10, 12. Further displacing force will deform the striker plate partially preventing the step 28 from jumping out of the groove.

We have found the advantages of the above embodiment to be: 1. The engagement of groove and step is more reliable than the prior art models.

2. The lock performs reliably despite variations in the fit of the security door in relation to the door frame.

It is to be understood that the word "comprising" as used throughout the specification is to be interpreted in its inclusive form, ie. use of the word "comprising" does not exclude the addition of other elements.

It is to be understood that various modifications of and/or additions to the invention can be made without departing from the basic nature of the invention. These modifications and/or additions are therefore considered to fall within the scope of the invention.

2006-01 -27.Z:\Speccfiatiowgrms.cmp.

Claims (6)

1. A lock assembly having a lock tongue and striker plate, the tongue having two or more side by side grooves in at least the inside face of the tongue directed normally to the latch tongue motion and the striker plate having an aperture which allows to and fro motion of the tongue and a tab projecting from the inside edge, the aperture allowing to and fro motion of the tongue for lock operation but the application of prying force causes the tab to enter the groove preventing tongue withdrawal.

2. A lock assembly as claimed in Claim 1, wherein the grooves are of rectangular section.

3. A lock assembly as claimed in Claim 2, wherein the grooves are 1-3mm wide.

4. A lock assembly as claimed in any one of Claims 1-3, wherein the grooves are 0.5-1.5mm deep. A lock assembly as claimed in any one of Claims 1-4, wherein the grooves are

15-20mm long. 6. A lock assembly as claimed in any one of Claims 1-5, wherein the grooves are at 3-7mm centres. 7. A lock assembly as claimed in any one of Claims 1-6, wherein the tongue has a striker plate entry portion devoid of grooves. 8. A lock assembly as claimed in Claim 7, wherein the portion is 5-10mm long. 9. A lock assembly as claimed in any one of Claims 1-8, wherein the tongue is L- shaped having a grooved part for engaging the striker plate and a hook part for engagement by a tongue actuator.

2006-01 -27,Z:\Speifications\egress.cap.wpd,6 A lock and striker plate assembly comprising a lock with a latch tongue having opposed faces for insertion through an aperture in a striker plate, one or both faces having at least two side by side grooves extending at least across the mid portion of the face, wherein the grooves are mutually separated one from the next adjacent groove by an intermediate margin in order that the tongue face may slide to and fro in the aperture past the striker plate, wherein adjacent grooves are mutually separated by intermediate margins of the face of the tongue, and a striker plate having an aperture for the tongue defined by a pair of opposed edges separated sufficiently to allow the opposed faces of a latch tongue to pass between the edges, at least one edge having a projection capable of entering a groove and obstructing the withdrawal of the tongue. 11. A lock assembly as claimed in Claim 10, wherein the projection is a tab deep. 12. A lock assembly as herein described with reference to and as illustrated in Figures 1-4. Dated this 2 7 th day of January, 2006. SANDERCOCK COWIE PATENT ATTORNEYS FOR EGRESS AUSTRALIA PTY. LTD. 2006-01 -27,Z: peicafiionm egr..scap.wpd 7