Closure fasteners – Bolts – Swinging
Patent
1996-01-22
1997-11-25
Lindsey, Rodney M.
Closure fasteners
Bolts
Swinging
292210, 292144, E05C 306
Patent
active
056903731
DESCRIPTION:
BRIEF SUMMARY
This invention relates to locks and more particularly to electromechanical locks.
Existing electromechanical locks typically comprise an electromagnet device which is attached to the inside of a door frame at a position where it contacts a fixed steel plate adjacent the outer edge of a hinged door. So long as power is applied to the electromagnet the door is secured or locked in its closed position. When power is removed the door is free to open. However, as well as being bulky and unsightly such locks have a number of operational disadvantages. The attraction force between the plate and magnet can be weakened (and thus the security of the door compromised) by faulty alignment of the plate or foreign matter such as dirt or oxides accumulating between the magnet and plate. Moreover such locks are restricted to fail safe operation and cannot be operated in the fail secure mode.
It is therefore an object of this invention to ameliorate the aforementioned disadvantages. Accordingly, this invention discloses a lock for a movable barrier such as a door or the like, said lock comprising a tongue pivotable on a first axis between a locking position where it engages a strike and an unlocked position where it is clear of said striker, a pawl pivotable intermediate its ends on a second axis between a first position where one end thereof abuts said tongue to hold it in said locking position and a second position where said one end is clear of the tongue and a set of toggles hingedly connected end to end between the other opposite end of the pawl and a third axis, the interconnected ends of said toggles being linked to a spring biased solenoid plunger and stop means movable between a fail secure position where, upon cessation of current through the solenoid, said toggles are aligned against said stop means in a substantially straight configuration to hold the pawl and tongue in said locking position and a fail safe position where, upon cessation of current through said solenoid, said toggles are offset to a release configuration against said stop means and said pawl and tongue being arranged to then pivot to said unlocked position upon a withdrawal force being applied to the striker.
Preferably said pawl and tongue are shaped so that the direction of force exerted therebetween forms a moment about said second axis which biases the pawl to said second position.
It is further preferred that the striker is deflectable on its mounting plate to one side against a spring bias so as to enable said striker to engage around the tongue while said tongue is stationary.
The currently preferred form of this invention will now be described with reference to the attached drawings in which:
FIG. 1 is a perspective view of the exterior of the lock,
FIG. 2 is a schematic cross-sectional view along the line A--A in the fail secure mode,
FIG. 3 is a schematic cross-sectional view along the line A--A in the fail safe mode, and
FIG. 4 is a perspective view of the striker.
The lock exterior may be fabricated from mild steel and be shaped to form an elongated one piece three sided housing which in use may be attached to the inside of a door frame (not shown) using screw holes 1. It may comprise a front face 1A having an aperture 2 into which a door mounted striker 3 enters, a lower wall 3A and an upper wall 3B which has been cut away and is thus not shown on the cross-sectionel views. Referring more specifically to FIGS. 2 and 3 there is shown inside the housing a hook shaped tongue 4 (in the locked position engaging the striker) which is pivotally mounted on a fixed axis 5, an elongated pawl 6 pivotally mounted on a fixed axis 7 and a set of toggles 8 mounted between one end 9 of the pawl and a fixed axis 10. These fixed axes 5, 7 and 10 extend between aligned apertures in the upper and lower walls of the lock housing. The toggles are coupled in series by a hinge 11 which is also connected by a link 12 to the spring biased plunger 13 of solenoid 14 secured to the upper wall of the housing. Preferably the link 12 sits within a diametrical gro
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Lindsey Rodney M.
Millner Monica E.
Trimec Securities Pty. Limited
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