GB2214968A - Door lock with automatically engaging cylindrical bolt - Google Patents

Abstract

A door lock includes a rectangular cylindrical bolt 11 mounted on a housing 10. A rotary cam 15 connected to a handle 14 is provided for withdrawing the bolt. A spring-loaded detent pin 17 mounted on the housing can coact with an abutment 12<d> on the bolt to retain the latter in its withdrawn position. A release member 19 is mounted for movement in a direction parallel to the bolt withdrawal direction, its end being shaped so that it is displaceable by contact with a coacting striker (not shown). A cam surface on the member 19 coacts with a peg 21 on the pin 17 to release the bolt when the member 19 is moved towards a withdrawn position on closing the door. Mechanisms are also provided for disabling the cylinder lock on one side of the door and for overriding the release member to hold the bolt in its withdrawn condition. <IMAGE>

Description

DOOR LOCKS This invention relates to door locks.

Most conventional nightlatch type door locks make use of a bolt which has a curved or angled face so that it is automatically retracted by contact with a coacting keeper as the door is being closed. It is considered, however, that the level of security of a door lock could be improved by using a plain rectangular section bolt instead of one with a curved or angled face, as it is more difficult to displace a plain bolt using a tool inserted in the gap between the door and its frame.

It is, however, desirable to provide for automatic locking on closing of the door and it is an object of the present invention to provide an automatically operating lock having a plain rectangular section bolt.

A door lock in accordance with the invention comprises a housing, a rectangular section bolt slideably mounted on said housing, spring means urging said bolt to a projecting position, withdrawal means for withdrawing said bolt to a withdrawn position, detent means for retaining said bolt in said withdrawn position and detent release means including a release member mounted on said housing for sliding movement in direction parallel to the bolt movement direction, said release member being spring urged to a projecting position and being displaceable in use, by closing of a door on which the housing is mounted, to a withdrawn position, said release member being coupled to said detent means to release said detent means on sliding movement of the release member towards its withdrawn position.

Preferably, said withdrawal means comprises a rotary cam mounted on the housing and having a pair of wings engageable respectively with a pair of abutment faces on a bolt lath attached to said bolt, said wings lying in plane which is spaced from the locus of an adjacent face of the bolt.

The rotary cam may also incorporate a cranked finger directed towards the bolt when the rotary cam is in a rest position, the bolt being provided with a coacting finger directed towards said rotary cam, said fingers coacting to provide dead bolt action.

An example of the invention is shown in the accompanying drawings, in which: Figure 1 is a back view of the lock with its back plate removed; Figure 2 is a section on line 2-2 in Figure 1; Figure 3 is a section on line 3-3 in Figure 1; and Figure 4 is a section on line 4-4 in Figure 1, but showing the lock with its back plate in position.

The lock shown in the drawings includes a housing 10 which has a flange 10a at one end thereof. The housing is intended to be mounted on a door with the flange 10a lying in a recess at the edge face of the door.

A rectangular section bolt 11 has a bolt lath 12 attached to it and this assembly is slideably mounted on the housing with the bolt projecting through a rectangular aperture in the flange 10a. The lath 12 is basically of U-shaped configuration, toggled at 12a to provide a tongue 12b for connection to the bolt 11.

The ends of the two limbs are bent at right angles to the general plane of the "U" to provide a pair of abutment faces 12C. The bolt 11 and attached lath 12 are slideable relative to the housing between the bolt-projecting position shown to a bolt retracted position in which the free end of the bolt 12 is substantially flush with the exterior face of the flange 10a. The bolt 12 is urged to the bolt projecting position by a coiled wire spring 13 in the housing.

For retracting the bolt from its bolt projecting position, tnere is provided a handle 14 mounted on the housing for rotary movement about an axis perpendicular to the general plane of the bolt lath 12. A cam 15 is mounted on the handle inside the housing and has a pair of oppositely projecting wings 15a which engage the respective abutment faces 12C on the bolt lath. These two wings lie in a plane which is spaced from the locus of the adjacent face of the bolt 11. As the handle is turned in either direction from its rest position shown, one of the wings 15a moves away from the flange 10a, pushing back the lath 12 and the other moves towards the flange 10a, but the spacing of the wings 15a from the locus of the bolt ensures that there is no collision between these parts.In this way it is possible to obtain a relatively long displacement of the bolt, by turning of the handle in either direction.

To provide a deadlocking action there is provided a finger 15b on the cam 15 which is cranked out of the plane of the wings 15b so as to lie in the path of a coacting finger lla on the bolt. When the handle is in its rest position, retraction of the bolt is prevented by end to end engagement of the fingers lla, 15b It will be noted from Figures 1 and 4, however, that there is a significant clearance between the ends of the fingers, which ensures that the fingers do not collide when the bolt is withdrawn normally by turning the handle. Figure 4 shows a handle restraining device 16 in the form of a ball mounted in a blind cross bore in the handle and urged by a spring onto a handle bearing surface of the housing.The bearing surface is formed with a notch to receive the ball when the handle is in its rest position. This ensures that the handle 14 does not turn under the influence of gravity if the bolt is retracted slightly by applying some tool to the bolt and that the fingers lla and 15b do collide to provide the required deadlock action in these circumstances.

Since the bolt is of rectangular section and does not have the inclined or curved face normally used on the bolt of a nightlatch type lock, the normal type of slam action cannot be obtained. A detent means is therefore provided for holding back the bolt in its retracted position and there is also a release means for releasing it automatically when the door on which the lock is mounted is closed.

This holding means includes a spring-loaded pin 17 slideably mounted in a socket in the housing and moveable in a direction perpendicular to the general plane of the bolt lath 12. The position of this pin 17 is controlled by a cam-slot 19a in a release member 19 mounted on the housing beside the bolt so as to be slideable in a direction parallel to the bolt movement direction. The release member 19 is urged by a spring 20 to a limit position determined by interengageable slots 19b, 10b on the release member and the housing.

In this limit position, an end portion of the release member 19 projects through a slot in the flange 10a and there is an inclined end face 19e on this end portion can coact with a keeper mounted on the associated door frame, such that the release member is displaced longitudinally as the door is closed. The cam slot 19a in the release member is engaged by a transverse peg 21 attached to pin 17, such that when the release member 19 is in its limit position as shown, the pin 17 is free to move into the path of the lath 12. When the member 19 is displaced longitudinally on closing of the door the cam slot causes the pin 17 to be displaced downwardly as viewed in Figure 3.Thus, on opening of the door, which involves firstly turning the handle to withdraw the bolt and then moving the door, the pin 17 can move to a position in which it prevents return movement of the bolt by engaging an abutment 12d on the lath 12. When the door is closed, the member 19 is displaced into the housing, releasing the pin 17 from the abutment 12d and allowing the bolt to be shot by the spring 13.

The lock also has a manually operable hold-back device 22, best seen in Figure 2. This includes a manual push button with a circlip 23 on its end. If the bolt is withdrawn by turning the handle the push button can be pushed in so that it coacts with another abutment 12e on the lath 12 (see Figure 1). If the handle is released in this position the bolt is held back and circlip 23 prevents the push button returning to its released position. Slight turning of the handle releases lath 12 from the circlip and resets the manual hold-back facility.

Figure 4 shows the lock cover 24 (or mounting plate).

This has a rotatable member 25 mounted on it for connection in the usual fashion to a pin-tumbler cylinder lock on the outside of the door. An abutment 25a on this member coacts with a pin 15e on the cam 15 so that when member 25 is turned in one direction it picks up the pin 15c and causes the cam 15 (and the handle 14) to turn with it to withdraw the bolt. There is also a wing 25b on member 25 which, by turning the cylinder of the lock in the opposite direction using its key can be positioned behind an abutment 12f on the lath. The lock is arranged to be lockable in this position and the wing 25b then provides a deadstop which prevents opening of the lock using the handle.

Claims (8)

1. A door lock comprising a housing, a rectangular section bolt slideably mounted on said housing, spring means urging said bolt to a projecting position, withdrawal means for withdrawing said bolt to a withdrawn position, detent means for retaining said bolt in said withdrawn position and detent release means including a release member mounted on said housing for sliding movement in direction parallel to the bolt movement direction, said release member being spring urged to a projecting position and being displaceable in use, by closing of a door on which the housing is mounted, to a withdrawn position, said release member being coupled to said detent means to release said detent means on sliding movement of the release member towards its withdrawn position.

2. A door lock as claimed in claim 1 in which said withdrawal means comprises a rotary cam mounted on the housing and having a pair of wings engageable respectively with a pair of abutment faces on a bolt lath attached to said bolt, said wings lying in plane which is spaced from the locus of an adjacent face of the bolt.

3. A door lock as claimed in claim 2 in which said rotary cam also incorporates a cranked finger directed towards the bolt when the rotary cam is in a rest position, the bolt being provided with a coacting finger directed towards said rotary cam, said fingers coacting to provide dead bolt action.

4. A door lock as claimed in claim 3 including a handle restraining device for restraining turning of a handle attached to said rotary cam under the influence of gravity if the bolt is displaced slightly towards its withdrawn position by applying a tool to the bolt.

5. A door lock as claimed in claim 4 in which said restraining device comprises a spring-loaded ball located in a cross-bore in the handle, said ball coacting with a V-groove within a bearing on the housing.

6. A door lock as claimed in any preceding claim in which said detent means comprises a spring-loaded pin movable relative to the housing in a direction perpendicular to the direction of movement of the bolt and coacting with an abutment on the bolt.

7. A door lock as claimed in claim 7 in which a cam surface is provided on said release member for displacing the pin out of engagement with said abutment when the release member is displaced towards its withdrawn position.

8. A door lock substantially as hereinbefore described with reference to and as shown in the accompanying drawings.