GB2306558A - Locks - Google Patents

Abstract

A mortice lock with "nightlatch" function comprises a deadbolt 3 and a spring bolt 4. The deadbolt is normally blocked by a detainer 9 but can be retracted by key operation of a locking cylinder 15. The spring bolt 4 can be retracted by handle operation only from the inside, via a follower 19. To retract the spring bolt from the outside, key operation of the cylinder 15 is required. For this purpose there is provided a second follower 24 linked to the cylinder thrower 17 through two link members 28 and 31. The thrower 17 lifts the member 31 which pivots the member 28 to turn the follower 24, this linkage serving to amplify the movement imparted by the thrower to the member 31 in its transmission to the follower.

Description

Locks The present invention relates to locks. More particularly the invention relates to door locks of the kind comprising: a casing; a deadbolt borne in the casing for extension and retraction; a spring bolt borne in the casing and biased to extend therefrom; a detainer borne in the casing for blocking the deadbolt against forced retraction; a locking cylinder mounted to the casing and having a rotatable thrower for displacing the detainer and retracting the deadbolt, said thrower being rotatable by operation of a correct key in the cylinder at least from outside the region closed by the door; a rotatable follower borne in the casing and linked to the spring bolt, said follower being rotatable to retract the spring bolt by operation of a handle, knob, push-bar or other such manipulable member from inside but not outside the region closed by the door; and a linkage within the casing for retracting the spring bolt by rotation of said thrower while the deadbolt is in its retracted position.

Such a lock has a so-called "nightlatch" function, meaning that the spring bolt cannot be retracted by handle or the like operation from the outside but only by key operation of the cylinder to turn the said thrower.

It is to an improvement of such a lock that the present invention relates and the invention accordingly resides in a lock of the kind stated where the aforesaid linkage between the thrower and spring bolt comprises: a second rotatable follower borne in parallel with the firstmentioned follower and linked to the spring bolt, said second follower being rotatable to retract the spring bolt independently of the first-mentioned follower; a first, pivotal linkage member pivoted in the casing at one end and linked to the second follower at the other end for rotating the same; and a second, translatable linkage member one end of which is linked to the first linkage member intermediate the ends of the latter and the other end of which is engageable by said thrower; whereby the distance through which said other end of the first linkage member is caused to move for rotating the second follower is amplified with respect to the distance through which said other end of the second linkage member is caused to move by rotation of said thrower.

The invention will be more particularly described, by way of example, with reference to the accompanying drawing which illustrates the internal mechanism of one preferred embodiment in the condition in which the deadbolt is retracted and the spring bolt extended.

Referring to the drawing, the illustrated lock is of mortice style, having a casing 1 normally closed by a cap (not shown) and with an attached forend 2. A deadbolt 3 is borne in the casing for extension and retraction between unlocking (illustrated) and locking conditions, and a spring bolt 4 is also borne in the casing, the bolt 4 having a chamfered head 5 to interact with a striking plate (not shown) in the conventional manner, and being biased to extend from the casing by a spring 6 compressed against a fixed block 6A The basic operation of the deadbolt mechanism is as described in GB-A-2281587.

Thus the bolt 3 has a head 7 guided through the forend 2, and a tail 8, of lesser width than the head, in parallel with a detainer 9 which is borne for lifting at right angles to the direction of movement of the deadbolt.

The detainer 9 carries a transverse bar 10 the two ends of which extend into respective rectangular apertures 11 in the two sides of the lock casing. A spring 12 acts on the detainer 9 normally to keep it in its lower (illustrated) position in which the bar 10 engages in one of two notches 13 or 14 in the upper surface of the bolt tail 8, depending on whether the bolt 3 is extended or retracted, to block the deadbolt against movement. More particularly, when the bolt 3 is extended and the bar 10 engages in notch 14, any end loads applied to the bolt head 8 in an attempt to force it back will be securely resisted by transference through the bar 10 to both sides of the lock casing.

A conventional locking cylinder 15 is mounted transversely through complementary apertures in the lock casing and fixed in place by means of a screw 16 from the forend 2 in conventional manner. The cylinder 15 has a rotatable thrower 17 for extending and retracting the deadbolt 3 in accordance with its direction of movement.

More particularly, to extend the deadbolt 3 from its illustrated position the thrower 17 is given one complete turn in the anti-clockwise sense (as viewed). As the thrower turns it first engages the underside surface of the detainer 9 to lift the same against the action of the spring 12 and carry the bar 10 out of notch 13 and clear of the top surface of the bolt tail 8. Thereafter the thrower engages in a gating 18 in the bolt tail and, while the detainer 9 is still lifted, throws out the bolt 3 to its extended position, finally releasing the detainer to fall under the action of the spring 12 with its bar 10 now engaging in the notch 14.Retraction of the deadbolt from this position is the reverse of this process, with the thrower 17 turning clockwise (as viewed) to lift the detainer 9, engage in gating 18 and pull in the bolt, and finally release the detainer 9 to fall with the bar 10 in the notch 13. The cylinder 15 may be double-sided, that is to say equipped with a tumbler mechanism at each end so that from either side of the door the thrower 17 can only be turned by the insertion of a correct key. Alternatively, it may be single-sided, with a tumbler mechanism at the outside end and a simple thumb turn at the opposite end for rotating the thrower from the inside. In either case, however, operation of the cylinder to extend and retract the deadbolt from the outside can only be achieved by use of a correct key.

A handle follower 19 is mounted for rotation on a bushing within the casing 1. This follower has a squaresectioned spindle hole 20, by which it is rotatably connected through a spindle (not shown) to a handle mounted on the inside face of the door. There is no corresponding handle on the outside face of the door, however, and the portion of the lock casing which faces the spindle hole 20 on the outside will be blanked off, preferably with a drill-resistant plate. The follower 19 has an ear 21 engaging a sliding plate 22 linked to the spring bolt 4. A compression spring 23 biases the plate 22, and thereby the follower 19, to the illustrated rest position, in which the spring bolt 4 can operate to latch the door when closed. To retract the spring bolt from the inside, the aforesaid handle is manipulated to turn the follower 19 clockwise (as viewed) and shift the plate 22 to the right (as viewed) against the combined action of the springs 23 and 6, thereby drawing in the whole of the bolt. Release of the handle then allows the mechanism to return to the illustrated position under the action of the springs 23 and 6, and the door will be latched again by the bolt 4 as soon as it is slam-closed.

In keeping with the "nightlatch" function of this lock, retraction of the spring bolt 4 from the outside can only be accomplished by key operation of the cylinder 15. In this way the door has security against unauthorised entry as soon as it is slam-closed. The linkage by which spring bolt retraction is effected from the cylinder 15 will now be described.

A second follower 24 is borne rotatably in parallel with the follower 19 but each of these followers is rotatable independently of the other. The follower 24 has an ear 25 engaging a sliding plate 26 linked to the spring bolt 4 in parallel with but separate from the plate 22. In particular, the plate 26 is not subject to the action of the spring 23. The follower 24 is articulated at 27 to a link 28 which is pivoted on a fixed pin 29. The link 28 is in turn pinned at an intermediate position 30 to the upper end of a lever 31 which extends through a vertical slot 32 behind the head 7 of the deadbolt 3 and terminates in a projection 33 directed towards the cylinder 15. A spring 34 acts between the pin 29 and the lever 31 to bias that lever anti-clockwise (as viewed) to the extent permitted by its engagement in the slot 32.

In order to retract the spring bolt 4 from the outside with the mechanism in the condition shown in the drawing, therefore, a correct key is inserted into the cylinder 15 and turned to partially rotate the thrower 17 in the clockwise direction (as viewed), full rotation of the thrower in this condition being blocked by its eventual abutment with the underside of the deadbolt tail 8. As the thrower 17 turns through this angle, it encounters the projection 33 at the lower end of the lever 31 and thereby slides that lever up through the slot 32 so as to pivot the link 28 anti-clockwise (as viewed). The link 28 accordingly turns the follower 24 clockwise (as viewed) to retract the spring bolt 4 with its ear 25.

As stated above, the sliding plate 26 linked to the ear 25 is separate from the plate 22 and not subject to the action of the spring 23. Only the action of the relatively lighter spring 6 therefore need be overcome when the bolt 4 is to be withdrawn by the follower 24 through the mechanism linked to the cylinder thrower 17, thereby minimising the torque which must be applied to the key in the cylinder 15 for this purpose. After opening the door the key can be turned back in the cylinder 15 to permit the mechanism to return to the illustrated condition.

The link 28 serves to amplify the movement of the upper end of the Sever 31 in transmitting movement from the thrower 17 to the follower 24. The sprung lever 31 has freedom to displace clockwise (as viewed) through a small distance in the slot 32 so that if the thrower 17 has been left in a displaced position in line with or above the projection 33 full retraction of the deadbolt 3 will not be hindered and the thrower 17 can be returned to its rest position by subsequent operation of the cylinder 15.

It will be appreciated that when the deadbolt 3 is extended the lever 31 is carried in the slot 32 clear of the locus of the cylinder thrower 17. When both bolts 3 and 4 are to be retracted from the outside, therefore, the deadbolt 3 is first retracted by a complete revolution of the thrower 17 as described above and retraction of the spring bolt 4 follows by an additional partial rotation of the thrower 17.

In a modified version of the above-described lock a manually-operated snib may be provided for holding the spring bolt 4 in its retracted position if so desired.

Another modified version in which the lock has also an "escape" function - that is to say where there is additional mechanism for retracting the deadbolt 3 together with the spring bolt 4 by operation of the inside handle - is described in our copending United Kingdom patent application no. [Agent's ref 11/95/1].

Claims (4)

1. A door lock comprising: a casing; a deadbolt borne in the casing for extension and retraction; a spring bolt borne in the casing and biased to extend therefrom; a detainer borne in the casing for blocking the deadbolt against forced retraction; a locking cylinder mounted to the casing and having a rotatable thrower for displacing the detainer and retracting the deadbolt, said thrower being rotatable by operation of a correct key in the cylinder at least from outside the region closed by the door; a rotatable follower borne in the casing and linked to the spring bolt, said follower being rotatable to retract the spring bolt by operation of a manipulable member from inside but not outside the region closed by the door; and a linkage within the casing for retracting the spring bolt by rotation of said thrower while the deadbolt is in its retracted position; said linkage comprising: a second rotatable follower borne in parallel with the first-mentioned follower and linked to the spring bolt, said second follower being rotatable to retract the spring bolt independently of the firstmentioned follower; a first, pivotal linkage member pivoted in the casing at one end and linked to the second follower at the other end for rotating the same; and a second, translatable linkage member one end of which is linked to the first linkage member intermediate the ends of the latter and the other end of which is engageable by said thrower; whereby the distance through which said other end of the first linkage member is caused to move for rotating the second follower is amplified with respect to the distance through which said other end of the second linkage member is caused to move by rotation of said thrower.

2. A lock according to claim 1 wherein said second linkage member is carried by a slot in the deadbolt for translation when engaged by said thrower, but with limited freedom to pivot within that slot away from the thrower; and comprising spring means normally biasing said second linkage member to lie within said slot in a pivotal position in which it is engageable by said thrower while the deadbolt is in its retracted position.

3. A lock according to claim 1 or claim 2 comprising first spring means for biasing the spring bolt to its extended position and second, stiffer spring means for biasing the first-mentioned follower to a rest position; the second follower being linked to the spring bolt so as to be subject to the action of said first spring means but not said second spring means.

4. A door lock substantially as hereinbefore described with reference to the accompanying drawing.