GB2288207A - A mortice lock with auxiliary thrower having precise detent means - Google Patents

Abstract

A cylinder-operated mortice lock has an auxiliary thrower 15, which increases the bolt throw and provides a deadlocking action, running in an arcuate track 22 in the lock case between the cylinder thrower/cam 13 and bolt 6. The auxiliary thrower 15 carries a spring-biased ball 24, ie a detent, which engages in recesses (27, 31, fig 3) in the lock case, thereby ensuring precise positioning of the auxiliary thrower at the ends of its travel. This detent arrangement applies no appreciable resistance to the movement of the auxiliary thrower once the ball is released from its recess. Stops 26, 29 are provided to halt the auxiliary thrower 15 at the extremities of its travel. Bolt 6 has a drive surfaces 30, 33 which engage the auxiliary thrower 15 so as to extend/withdraw the bolt 6. <IMAGE>

Description

Locks The present invention relates to locks. More particularly, the invention relates to cylinder-operated locks of the kind comprising a lock case bearing a reciprocable bolt, adapted to be attached to a door or other closure, and a locking cylinder mounted to the case having a rotatable thrower for shifting the bolt when the cylinder plug is released and turned by a proper key.

In order to increase the throw of the bolt in such a lock it is known, e.g. from Dutch patent specification No.

174973, to interpose an auxiliary thrower running in an arcuate track in the lock case, between the cylinder and bolt. The geometrical relationship of the bolt and auxiliary thrower also serves to block the bolt against retraction under end pressure when in the extended condition. In order to provide a yieldable detent action on the auxiliary thrower in its two extreme positions corresponding to full extension and retraction of the bolt, a leaf spring is applied over the top of the auxiliary thrower, which presses it down towards the respective end of its track.Owing to the arcuate form of the path described by the auxiliary thrower, however, the force applied to it by this leaf spring is at a maximum at the mid-point of its travel, where no detent action is required, meaning that an appreciable operating force must be applied by the user to shift the bolt between its extended and retracted positions. The leaf spring also occupies a significant amount of space within the lock case.

In one aspect the present invention seeks to improve the detent springing arrangement of the auxiliary thrower in a lock of the above character and accordingly proposes a lock comprising a case bearing a reciprocable bolt; a locking cylinder mounted to the case having a thrower rotatable by a proper key; an auxiliary thrower borne to follow an arcuate path within the case, the auxiliary thrower being engageable by the cylinder thrower and adapted to extend and retract the bolt in accordance with its direction of movement along said arcuate path; and a spring-biased detent element (e.g. a ball) mounted in the auxiliary thrower and urged into a complementary recess in the lock case when the auxiliary thrower is in the position corresponding to full extension of the bolt.

Preferably the detent element is also urged into a second complementary recess in the lock case when the auxiliary thrower is in the position corresponding to full retraction of the bolt. With such an arrangement, once the spring-biased element has been released from the respective recess at the commencement of the auxiliary thrower's movement it will apply no further appreciable resistance, as opposed to the leaf spring whose force upon the auxiliary thrower increases during the first half of the latter's movement. The detent arrangement in a lock according to the invention may also provide more precise positioning and a more positive detent action for the auxiliary thrower than the known leaf spring, and is more compact.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of a lock in accordance with a preferred embodiment of the invention, with its cap removed; Figure 2 is a front view of the lock of Figure 1; Figure 3 is a side view of the cap for the lock of Figure 1; Figures 4, 5 and 6 are respectively front, side and rear views of the auxiliary thrower for the lock of Figure 1, prior to assembly with its ball and spring; and Figures 7 and 8 are respectively part-sectional views through the auxiliary thrower and lock case of Figure 1, in two different positions of the auxiliary thrower.

With reference to Figure 1, the illustrated lock has a case 1 for mounting in a mortice in a door edge, comprising a formed plate 2 defining one side and the upper, lower and rear edges of the case, an attached forend 3, and a cap 4 (Figures 2 and 3) removably secured by screws passing into threaded posts 5 on the plate 2.

The cap 4 is itself covered by a drill-resistant plate 4A. A reciprocable deadbolt 6 has a head 7 passing through an aperture in the forend 3 and a tail 8 with a lateral pin 9 running in a linear slot 10 in the plate 2.

For extending and retracting the bolt 6 there is a conventional double-sided locking cylinder 11 mounted laterally through the lock case and secured by a screw 12. As usual, the cylinder 11 has a thrower or "cam" 13 lying within the case 1 which can be rotated in either sense through 3600 from either side of the door by releasing and turning the respective cylinder plug 14 with a proper key.

Interposed between the cylinder 11 and bolt 6 is an auxiliary thrower 15 of the form more fully shown in Figures 4 to 6. It has a body with a main forward part 16 and rear part 17, through which runs a notch 18 to receive the cam 13. An arcuate rib 19 extends from the part 16 to run in an arcuate slot 20 in the cap 4 (Figure 3) and a stump 21 extends from the part 17 to run in an arcuate slot 22 in the case plate 2. A blind bore 23 is also formed in the part 16 to house the detent components for the auxiliary thrower which, as seen in Figures 7 and 8, comprise a bearing ball 24 and a compression coil spring 25 acting to urge the ball out of the bore 23.

In the condition of the lock shown in Figure 1, the bolt 6 is fully extended and the auxiliary thrower 15 lies at the leftward (as viewed) extremity of its path of movement defined by the slots 20 and 22, against a stop 26. If any end pressure is applied to the bolt head 7 in this condition it will be resisted by the auxiliary thrower, the geometry of the contact surfaces between bolt and auxiliary thrower being such that there will be no tendency for the auxiliary thrower to be displaced rightwards along its arcuate track by loads acting inwards on the bolt in this condition. It is, however, desirable that a positive detent action is applied to the auxiliary thrower in this condition to avoid the risk that it could be displaced by any impacts or vibration applied to the door.For this purpose the ball 24 carried by the auxiliary thrower extends into a recess 27 (Figures 3 and 7) formed by an extension of the slot 20 in the cap 4, under the bias of the spring 25.

To retract the bolt 6 from the position shown in Figure 1, a proper key is turned in either cylinder plug 14 to rotate the cam 13 clockwise (as viewed) through one complete revolution. In so doing the cam 13 enters the notch 18 in the auxiliary thrower 15 and engages one of its margins 28. The force applied to the auxiliary thrower in this sense cams the ball 24 inwards from the recess 27 and continued turning of the cam 13 drives the auxiliary thrower rightwards along its slots 20,22 until it is finally released by the cam 13 and lies at the opposite extremity of its path, against a stop 29.In the course of this movement the rear part 17 of the auxiliary thrower engages a drive surface 30 on the bolt tail 8 to retract the bolt, the distance through which the bolt is moved during this retraction (and subsequent extension) significantly exceeding that through which it would be moved by direct contact from a cam such as 13.

Throughout this movement of the auxiliary thrower the ball 24 runs along the inner face of the cap 4, as indicated in Figure 8, and imposes no appreciable resistance on the movement of the auxiliary thrower, eventually springing into another recess 31 in the cap (Figure 3) to apply a detent action when the auxiliary thrower reaches its rightward extremity.

To extend the bolt from the latter condition, a proper key is turned in either cylinder plug 14 to rotate the cam 13 anticlockwise (as viewed in Figure 1) through one complete revolution. In so doing the ball 24 is cammed inwards from the recess 31 and the auxiliary thrower 15 is driven back to its Figure 1 position by engagement of the cam 13 with the margin 32 of the notch 18, the bolt being extended by engagement of the part 17 with a drive surface 33 on the bolt tail.

Claims (5)

1. A lock comprising a case bearing a reciprocable bolt; a locking cylinder mounted to the case having a thrower rotatable by a proper key; an auxiliary thrower borne to follow an arcuate path within the case, the auxiliary thrower being engageable by the cylinder thrower and adapted to extend and retract the bolt in accordance with its direction of movement along said arcuate path; and a spring-biased detent element mounted in the auxiliary thrower and urged into a complementary recess in the case when the auxiliary thrower is in the position corresponding to full extension of the bolt.

2. A lock according to claim 1 wherein said detent element is urged into a second complementary recess in the case when the auxiliary thrower is in the position corresponding to full retraction of the bolt.

3. A lock according to claim 1 or claim 2 wherein said detent element is a ball.

4. A lock according to any preceding claim wherein the auxiliary thrower has a portion guided by an arcuate slot in the case, the detent element is borne to extend at least partially through said portion and the or each said complementary recess is formed as an extension to said slot.

5. A lock substantially as hereinbefore described with reference to the accompanying drawings.