GB2039586A - Lock assembly for a door - Google Patents

Abstract

A lock assembly comprises a rotatable follower (12) operated by a knob or lever (not shown) on a door, a slidable runner member (6) with which the rotatable follower is engaged, a relatively heavy coil spring (7) interposed between the slidable runner and a fixed abutment (1b), and relatively light springs (13) accommodated in a latching nose (4) which is slidable on flat bearing portions (6d) of the runner to allow latching without movement of the runner. <IMAGE>

Description

SPECIFICATION Lock assembly for a door The present invention relates to a lock assembly with a latch bolt for use with a door. A primary object of the present invention is to improve the mechanism for operating the latch bolt so that a lock of the type described may function positively with reduced size and weight.

According to the invention there is provided a lock assembly for a door, comprising a rotatable drive member rotated by an operating member, a slidable drive member engaged by said rotatable drive member, a relatively heavy coil spring interposed between said slidable member and an element fixed relative thereto and at least one relatively light coil spring accommodated in a latch bolt and engaged by at least one corresponding bearing portion of said slidable member.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a lock assembly according to the present invention; Figure 2 shows the lock assembly in exploded perspective; Figure 3 shows the assembly of Figure 1 with a cover removed; Figure 4 illustrates an operative position of the assembly indicated in Figure 3; Figure 5 shows in perspective the details of a latch bolt and its associated members; and Figure 6 indicates an operative position of the mechanism depicted in Figure 5.

Referring to the drawings, a lock assembly of the invention includes a channel-shaped frame 1 having an opening 2 at one longitudinal end and carrying a mounting plate 3 integrally therewith. A latch bolt 4 is slidably received in a channel-shaped dead bolt 5 which is in turn slidable within the frame 1. These bolts 4 and 5 are both movable into and out of the frame through the opening 2.

A flat spring seat 1 b extends from and substantially perpendicular to a bottom wall la of the frame 1 so as to retain one end of a relatively heavy i.e.

strong coil spring 7, the other end of which is anchored to a member 6 adapted to drive the latch bolt 4. The drive member 6 is therefore constantly biased by the spring 7 toward the opening 2 of the frame. The drive memberS, has a pair of parallel flat extensions 6a directed rearwardly along opposite side walls icoftheframe 1, and each of these extensions is formed with a recess 6b. One of the extensions 6a is shown to include a lug Sc which is longitudinally, slidably engaged in an elongate slot (not shown of the frame 1. The engagement of the lug 6c with the slot thus limits the forward movement of the drive member 6.

The dead bolt 5 is provided with a portion 5a extending rearwardly along the inner surface of one of the extensions 6a of the drive member 6. This extension 5a of the dead bolt is slotted as at Sb while a bottom wall Sc is notched as at Sdto guide the spring seat 1 b of the frame therethrough. A pin 9 extends from the bottom wall Sc of the dead bolt to retain a positioning leaf spring 8.

A member 10 for driving the dead bolt 5 is journalled in the frame 1 and in combination with the frame 1, a closure member or cover 11 constitutes a housing of the lock assembly. The drive member 10 has a central bore 10a in which a stub shaft of rectangular cross-section (not shown) is engaged.

This stub shaft is to be rotated selectively by a thumb piece or a cylinder latch associated with each of the operating members, in the form of knobs or levers, on opposite sides of a door. A drive arm 10b extends from the outer periphery of the drive member 10 into engagement with the slot Sb of the dead bolt 5. Also provided on the outer periphery of the drive member 10 is a projection 1 Oc aligned in position with the drive arm lOb and engaged with the free end of the leaf spring 8.

A drive disc 12 is rotatably mounted on the dead bolt drive member 10 at its central opening 12a.

Radial shoulders 1 2b on the circumference of the disc 12 are engaged in the recesses 6b provided to the first drive member 6.

The disc 2 is also formed with an arcuate slot 12c in which is movably received an arcuate actuating lever (not shown) operatively connected with the knobs or levers.

The latch bolt 4 has a recess or chamber defined by a common front wall 4a and two rear walls 4b each of which is formed with a longitudinally extending through opening 4c. Relatively light, i.e.

weak, coil springs 13 are positioned between the front wall 4a and two rear walls 4b while flat bearing portions 6d of the drive members extend through the respective openings 4c of the rear walls 4b into engagement with the rear ends of the corresponding coil springs 13 as in Figure 5.

A cover plate 14 is rigidly connected to the latch bolt 4 with its tabs 14a pressed onto recessed portions 4d of the latch bolt. Tab pieces 14b on parallel extensions of the cover 14 are detachably engaged with shoulders 6e on the drive member 6.

The lock assembly having the above construction will be operated as follows. When a door carrying the lock assembly therewith remains in a open position, the relatively heavy coil spring 7 keepsthe latch bolt drive member 6 advanced whereby the latch bolt 4 remains extended beyond the frame 1 under the action of the relatively light coil springs 13 interposed between the bearing portions grand latch bolt wall 4a (Figures 3 and 5). As the door is moved from the an open to a closed position, the latch bolt 4 engages a co-operating metal fixture on a pillar ot the like and thereby retracts while compressing the coil springs 13 (Figure 6). Upon full closure of the door, the latch bolt 4 snaps into the metal fixture on the pillar by the returning action of the coil springs 13.

To open the door from the closed position, a knob on the door is turned in either direction so that its associated arcuate lever rotates the disc 12. Then either one of the shoulders 12b of the disc 12 moves the drive member 6 rearwardly and thereby the latch bolt 4 retracts due to engagement of the shoulders 6e with the corresponding tab pieces 1 4b of the cover 14 (Figure 4).

When the lock has its associated rectangular stub shaft rotated by a cylinder latch or the like while the door is in the closed position, the dead bolt drive member 10 is rotated causing the dead bolt 5 to extend into a latching position with its drive arm lOb extending through the slot 5b of the dead bolt.

Turning the drive member 10 in the opposite direction will bring the dead bolt 5 back to an unlatching retracted position.

It will thus be appreciated that the present invention reduces the size and weight of a lock of the type described while ensuring positive actions of the latch bolt.

The construction and operation of the bolts 4 and 5 by way of their associated driving members and intermediate members, forms the subject of our copending U.K. Patent Application No. (our ref. 101393M).

Claims (7)

1. A lock assembly for a door, comprising a rotatable drive member rotated by an operating member, a slidable drive member engaged by said rotatable drive member, a relatively heavy coil spring interposed between said slidable member and an element fixed relative thereto, and at least one relatively light coil spring accommodated in a latch bolt and engaged by at least one corresponding bearing portion of said slidable member.

2. An assembly as claimed in claim 1, wherein one end of said relatively heavy coil spring engages a spring seat formed on a frame of the lock assembly and the other end thereof engages said slidable drive member so as to bias the drive member towards an opening at one end of the frame.

3. An assembly as claimed in claim 2, wherein said latch bolt is engaged with said slidable drive member, so that rotation of said operating member to cause said drive member to move away from said opening causes retraction of said latch bolt as well as compression of said relatively heavy coil spring.

4. An assembly as claimed in any one of claims 1 to 3, wherein said latch bolt has an internal chamber containing said at least one relatively light coil spring. one end of said spring engaging a first wall of the chamber and the other end being engaged by at least one bearing portion of the slidable member, which projects into said chamber, the arrangement being such that with the door in an open position, in use, the slidable member is biased by said relatively heavy coil spring so that it keeps the latch bolt in its extended position, closure of the door causing the latch bolt to engage the door frame and thus retract to compress said at least one relatively light coil spring, and said at least one spring causing the latch bolt thereafter to extend into its associated recess in the door frame.

5. An assembly as claimed in claim 4, wherein said latch bolt comprises a first part defining said chamber and having said first wall of the chamber, and a second part in the form of a cover plate substantially closing the chamber except for at least one opening in a further wall of the chamber opposite said first wall, through which opening said at least one bearing portion projects.

6. An assembly as claimed in any one of ciaims 1 to 5 in which two relatively light coil springs are accommodated in said latch bolt.

7. A lock assembly for a door substantially as hereinbefore described with reference to and as shown in the accompanying drawings.