AU633133B2 - Electrical door latch release mechanism - Google Patents

Description

II i <t 633

AUSTRALIA

Patents Act 1952 COMPLETE SPECIFICATION 9999 99 9 9 It t I it Applicant: HARCOR SECURITY SEALS PTY LIMITED Address 2A Wilmette Place, Mona Vale, New South Wales, Australia Address for Service: Chrysiliou Moore Chrysiliou P.O. Box 373 Collaroy Beach NS'W 2097 Complete Specification for an invention entitled: "DOOR LATCH RELEASE MECHANISM" The following statement is a full description of this invention, including the best method of performing it known to me: 8 016838 240890 -2- This invention relates generally to door locks. In particular, this invention is concerned with a door latch release mechanism in which a pivotal striker or keeper is latched by a stop and releasable by rotation of the stop. In one embodiment, the invention includes an arrangement whereby the stop may be energised electrically to release the striker or energised electrically to lock the striker by use of a reversible armature or a similar arrangement.

Electrically operated door latch release mechanisms mounted on door frames and the like for locking or unlocking doors from remote locations such as in security buildings are known. There are many problems associated with known mechanisms. These include the failure of many prior art mechanisms to operate when a load is applied to the door.

For instance, if a wind exerts force against the door or if g a person leans against the door, the relationship between I the striker and the latch may become distorted, so ct i Ithat deactivat-on of the latch does not free the striker.

Another problem arises from attempts at forced entry. In some prior art mechanisms, the striker is latched by a 4I relatively small pin or the like and the exertion of force il ,o can cause this pin to bend or break, thus releasing the door in an unauthorised situation.

Many prior art mechanisms are difficult to clean or service because they lack ready access ;o working parts. Many are constructed With insufficient chassis strength. There is a need for a mechanism which can permit access to parts and which has a strong chassis.

~r r- C 3 In addition to the above, it is desirable to provide a door latch release mechanism which has a dual mode of operation, so that the mechanism can be converted from one which is latched when energised to one which is unlatched when energised. There is a need for a dual mode operation which is simple to convert and which minimises the risk of error on the part of the person effecting the conversion.

French Patent No. 1,021,024 discloses a door latch release mechanism in which the striker is latched by thrusting against a shaft rather than being held by a relatively small pin or the like as mentioned above. However, because the striker thrusts against the flat of the shaft, -exertion of force on the striker will transmit a torque with the risk of distortion of the mechanism.

It is an object of this invention to provide a door latch release mechanism which is capable of overcoming or substantially alleviating some or all of the problems referred to above. It is a further object of the invention to provide a door latch release mechanism which may be adapted easily to conversion from the "energised locked" configuration to the "energised unlocked" configuration.

Accordingly, this invention comprises a door latch release mechanism having: a housing adapted for mounting in a door jamb; a striker mounted on a shaft in the housing for pivotal

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;j i I I- I I d~ 3a movement between a door lock tongue engagement position and a door lock tongue release position; a stop mounted in the housing and having a portion capable of contacting the striker so as to latch the striker and prevent pivoting thereof from the door lock tongue engagement position, the portion of the stop being generally semi-circular in cross-section; and means for rotating the stop about its axis to an extent effective to release the striker; characterised in that the stop has its longitudinal axis parallel to the longitudinal axis of the shaft, the striker has an elongated edge parallel to each of said axes and the portion of the stop is adapted to engage substantially the whole of the elongated edge in a tangential manner.

The invention will now be described with reference to

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I I I -4preferred embodiments thereof, as follows.

o 00 06 e 660 o 00 o 0 0 .000 Preferably, the stop is rotated by electromagnetic means comprising an armature attached to the stop and a core magnetised by a surrounding coil, the armature and the coil each having an inclined surface capable of attraction to each other in response to the application of electrical energy. In this embodiment, the armature is not affected by gravity and the forces acting on the armature are identical for left hand and right hand doors, which affords the mechanism of the present invention added advantages over the prior art.

In an especially preferred embodiment, the armature is reversibly attached to the stop; reversing of the armature changes the direction of rotation of the stop, thus enabling conversion of the mechanism from a configuration where activation of the armature latches the striker, to a configuration where activation of the armature unlatches the striker. The conversion may be effected within a few seconds and has significant advantages in enabling the reduction of the amount of stock carried by locksmiths.

As illustrated in the Drawings discussed below, the shaft on which the striker is mounted preferably has its axis parallel to the axis of the stop, the striker has an elongated edge parallel to each axis and the portion of the stop is adapted to engage substantially the whole of the elongated edge. This arrangement adds strength to the latching of the striker and reduces wear along the site of engagement, so that the permissible loading of the door is 0000 0 L.

0 0I 6 0 p -r increased.

In addition, the elongated edge of the striker is preferably tangential to the circumference of the stop, so that attempts at forced entry would not achieve release of the door, unless the force applied is so great that the mechanism itself breaks.

The striker should be biassed away from the stop, so that release of the striker causes it to pivot on the shaft. A return spring may be provided for this purpose.

Similarly, the stop should be biassed towards disengagement .444 4 of the striker. This may be accomplished by a return spring, 4 which must oppose, for example, the magnetic force generated 4#4444 by the coil.

As an alternative, rotary magnets may be located one at each end of the stop. The magnets act in opposing directions and i may be operated by a change-over switch. Because the spring opposing the magnetic force of the coil can be omitted in t this embodiment, the operating force may be increased. This can enhance reliability and operation under low voltage 20 conditions. In addition, with this configuration it is 4.44 j 4° possible to seal the striker/armature/coil unit and to effect reversal of rotation of the stop by changing the electrical connections to the rotary magnets.

Instead of using a return spring or a pair of rotary magnets as described above, the stop may be motor driven. If geared motors are used, the force on the stop may be increased to such aii xtent that the door lock will remain operational II I~ -6- 9999 o 9 It 9 9 4 1 despite external forces exerted on the door such as a strong wind or a human body.

The housing is preferably made of a mild steel bar split unevenly on both ends and bent intD two hat shaped sections of different depth (or manufactured of two separate bars joined together by welding or brazing), so that a face plate with one inclined face for the depression of dead latch buttons can be attached over the full length of the chassis.

This configuration affords a proper bearing surface and gives added strength.

The chassis may be provided with a cover, the removal of which may permit cleaning and servicing as well as access to the armature and/or the coil.

In a situation where it is desired to change the voltage to be applied to the mechanism, the coil which is wholly contained within the chassis and accessible as described, may be replaced in a relatively simple operation, rather than having to discard the whole mechanism.

The coil magnetised core which may be of circular or square 20 cross section with one inclined face can be screwed to one end of the chassis and forms a part of a magnetic path. The armature, preferably of trapezoidal cross section, is fastened to the stop which passes through the flanks of the chassis. Activation of the armature causes a clockwise or anticlockwise rotation of the stop if the coil is energised or de-energised. Once the stop has rotated to a sufficient extent, the edge of the striker is released and the striker pivots to free the door lock tongue.

It 6 9.9 9 99 wrr. y ii -7- The invention will now be described with reference to the Drawings. It is to be understood', however, that the Drawings are for the purposes of illustration only and are not to be interpreted as limiting on the scope of the invention.

In the Drawings: Figure 1 is a sectional side view of an embodiment of the invention; Figure 2 is a sectional plan view of the core and coil along the lines A A of Figure 1 and viewed from above; 10 Figure 3 is an elevation of the lower part of the o o embodiment in Figure 1 in direction B, with the cover removed; Gotta: Figure 4 shows a cross section of the latching mechanism viewed from above; .°go ~Figure 5a is a sectional plan view along the lines A A of Figure 1 and viewed from below; Figures 5b and 5c show the armature in two configurations; and 4W Figure 6 details the operation of the striker mechanism.

r o. Referring first to Figure 1, a steel bar 1 of rectangular cross-section is split and bent into two hat shaped sections of different depth 2 and 3 so that a chassis is formed to which a face plate 4 can be fastened by screws 5. Face plate S4 has one inclined face (refer Figure 2) for the operation I of dead latch push buttons.

Two compartments 6 and 7 are formed by the chassis and both compartments are easily accessible after removal of -8cover 8 held by screw 9.

Compartment 6 contains electromagnetic parts for the operation of the latch release. Compartment 7 contains the electrical parts for monitoring the state of the latch release, although these parts have been omitted from the Drawings.

Steel bar 1 includes flanks 10 and 11 which define between them a central compartment containing striker or tongue release 12 (refer Figure 4) pivotally mounted on shaft 13 10 and held by spring tension (the spring is not shown) against thrust plate 14 so as to engage tongue 15 of an adjacent door lock. Elongated ground edge 16 of striker 12 is opposed by the solid part of stop 17 (refer Figures 1 and 4) and o o aoa thus is prevented from rotation about shaft 13, unless stop 17 rotates clockwise by approximately 20 degrees to allow edge 16 to pass through the centre of stop 17.

li4 Rotation of stop 17 is accomplished by armature 18 (refer Figures 3, 5a and 5b) fastened to stop 17. The movement of t t armature 18 is limited by projections 19 and 20 (Figures 1 and 5a). Armature 18 has a trapezoidal cross section opposed by the inclined face of core 21 (Figures 1 and 2) so that a Soo diminishing air gap is created between armature 18 and core 21 if coil 22 (Figures 1, 2 and 3) is energised. Movement of armature 18 is opposed by torsion spring 23 (Figure 1).

Referring especially to Figure 6, striker 12 pivoted around shaft 13 is prevented from rotating in the direction of the arrow shown by stop 17 resting in bearings 34. Stop 17 has a centre portion of semi-circular cross-section. The latched 9 -9condition of striker 12 thrusting against the door tongue (not shown in this Figure) prevents the opening of the door.

Armature 18 is fastened by pin 26 to stop 17 and is attracted to the inclined surface of core 21 when magnetised by the coil surrounding it (not shown in this Figure), thus rotating stop 17 in the direction of the arrow shown. This rotation in turn releases striker 12 and allows it to pivot about shaft 13.

By withdrawing armature 18 from pin 26 and inserting 10 armature 18 the opposite way, and rotating it by I g approximately 180 degrees, (refer Figure 5c) the direction of rotation of stop 17 can be changed, thus locking striker 12 if the coil surrounding core 21 is energised. In this t configuration, the torque of spring 23 should be reversed by changing the engagement point of one of its ends. In addition, screw 24 (Figure 1) should be slackened and core 21 should be rotated by 160 degrees (being 180 degrees less the operational movement of 20 degrees).

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Claims (8)

1. A door latch release mechanism having: a housing adapted for -Irwting a door jamb; a striker mounted on a shaft in the housing for pivotal movement between a door lock tongue engagement position and a door lock tongue release position; a stop mounted in the housing and having a portion capable of contacting the striker so as to latch the striker and prevent pivoting thereof from the door lock tongue engagement position, the 10 portion of the stop being generally semi-circular in cross section; and means for rotating the stop about its axis to an extent 0r00e effective to release the striker; characterised in that the stop has its longitudinal axis parallel to the longitudinal axis of the shaft, the 0o striker has an elongated edge parallel to each of said o axes, and the portion of the stop is adapted to engage 0 substantially the whole of the elongated edge in a 6* o tangential manner. a

2. A door latch release mechanisi a; zlaimed in claim 1, wherein the stop is rotated by electromagnetic means comprising an armature attached to the stop and a core magnetised by a surrounding coil, the armature and the core having opposed inclined surfaces, the inclined surface of the armature being attracted towards the inclined surface of the core in response to the application of electrical energy to the coil. Fl 'Vt, C I; II C r I 11

3. A door latch release mechanism as claimed in claim 2, wherein the armature is reversibly attached to the stop and the core is rotatable with respect to the housing to an extent sufficient for the direction of rotation of the stop to be reversed when the armature is reversed.

4. A door latch release mechanism as claimed in any one of claims 1 to 3, which includes means to bias the stop towards the position where the striker is released, thr bias means being chosen from the group consisting of: 10 a return spring mounted on the stop; a rotary magnet located at each end of the stop and operable to act in opposing directions by a change over switch; and a geared motor located at each end of the stop.

5. A door latch release mechanism as claimed in any one of claims 2 to 4, wherein the housing is a chassis having a cover the removal of which permits access to the armature and/or the coil.

6. A door latch release mechanism as claimed in claim wherein there is attached to the chassis a face plate having an inclined surface adapted to depress a dead latch button on the door lock.

7. A door latch release mechanism as claimed in claim or 6, wherein the chassis is made of mild steel.

8. A door latch release mechanism as claimed in claim 1, I t;i i i i i i: i 12 substantially as herein described with ref eacc .ice to the attached drawings. Dated this 4th day of November 1992. HARCOR SECURITY SEALS PTY LIMITED By its Patent Attorney KERRY MOORE CHRYSILIOU of CHRYSILIOU MOORE CHYRSILIOU *rt~ 4 4, 4**4 4. .4 .4 4 0~ 44 0e$q~q 4 0 4, 4* 9 4S 4. .44441 I 4 It III,'. I 4, A,