Locks – Operating mechanism – Using a powered device
Patent
1997-05-06
1998-11-24
Boucher, Darnell M.
Locks
Operating mechanism
Using a powered device
70282, 70496, 70283, 70375, E05B 4900
Patent
active
058393056
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an electrically operable cylinder lock.
It has long been considered desirable to provide an electrically operable cylinder lock which is fully self contained and which is such a size and shape that it can be substituted for an ordinary cylinder lock, but this goal has proved elusive for several reasons.
One problem which arises is that of ensuring that the electrical energy required to operate the lock is minimised. We have previously proposed energy saving locking devices using an electromagnet to restrain movement of a detent element. With this arrangement the detent element coacts with a movable part of the lock so that when the movable part is in a normal rest position the air gap between the detent element and the electromagnet one is minimised so that only a relatively low current is required to restrain the detent from moving into a locking position as the movable part is turned out of its normal rest position. The inclusion of such an arrangement in an electrically operated cylinder lock poses problems because of the confined space available and because it must be resistant to so-called "rapping"--a lock opening technique in which torque is applied to the movable part of the lock whilst the body of the lock is tapped repeatedly to make any spring-loaded detents in the lock jump out of their locking positions.
A lock device in accordance with one aspect of the present invention comprises a body having a bore, a rotatable barrel in said bore, said barrel being provided with an axially extending locking slot formation, an axially extending bar slidably mounted in the body for radial movement relative to the barrel between a detent position in which the bar projects into the locking slot formation to limit turning of the barrel and a release position in which the bar is clear of said lock slot formation, a cam formation on said barrel for displacing the bar from its detent position and its release position as the barrel is turned in the body and an electromagnet energisable to retain said bar by magnetic attraction in its release position.
Preferably, the cam formation on said barrel comprises two separate cam portions at opposite ends of said locking slot, acting on portions of the bar at opposite ends thereof. In this case, the bar is preferably urged towards the barrel by two independent springs acting on opposite ends of the bar.
Alternatively, the cam formation on the barrel may be of constant cross-sectional shape, spaced cam-engaging portions being provided at opposite ends of the bar.
The cam formation on said barrel may have a single peak profile so as to locate the bar in its release position when the barrel is in a normal rest position, but preferably the cam formation has a twin peak profile such that in a normal rest position the bar is in its detent position, but is displaced to its release position by initial turning of the barrel out of the normal rest position. In this case, the spring loading of the bar can be used to locate the barrel in its rest position. This arrangement also makes it significantly more difficult to release the lock by so-called "rapping".
Preferably, the electromagnet is mounted in the body so as to be freely movable radially relative to the barrel and the cam formation on the barrel is dimensioned so as to ensure that the bar makes actual physical contact with the electromagnet and displaces it radially outwardly as the bar is moved to its release position.
The electromagnet may be housed in a carrier which has a slot in which the bar is slidable and location means for springs which act on the bar. The carrier with the electromagnet, bar and springs pre-assembled with it, can be inserted into an opening in the body during assembly of the lock. When the electromagnet is free to move axially as described above, such freedom is provided by allowing free movement of the electromagnet within the carrier.
Another problem which arises is that there is a need in an electrically operated lock to provide some sort of switch to energise the lock ci
REFERENCES:
patent: 3889501 (1975-06-01), Fort
patent: 4712398 (1987-12-01), Clarkson et al.
patent: 4807454 (1989-02-01), Sengupta et al.
patent: 4827744 (1989-05-01), Namazue et al.
patent: 5010750 (1991-04-01), Boser et al.
patent: 5351042 (1994-09-01), Aston
patent: 5561997 (1996-10-01), Milman
patent: 5699686 (1997-12-01), Neumayer et al.
Boucher Darnell M.
Yale Security Products Limited
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