GB2281585A

GB2281585A - Key actuated mechanism in window or door lock

Info

Publication number: GB2281585A
Application number: GB9318506A
Authority: GB
Inventors: Nigel Philip Shenton
Original assignee: PLUS PLAN
Current assignee: PLUS PLAN
Priority date: 1993-09-07
Filing date: 1993-09-07
Publication date: 1995-03-08
Anticipated expiration: 2013-09-07
Also published as: GB9318506D0; GB2281585B

Abstract

A key-operated locking mechanism for a door or window comprises a body (1) with a generally cylindrical bore housing a rotatable actuating barrel (35). Rotation of the actuating barrel (35) causes movement of a locking detent (33) from a retracted unlocked position to an extended locking position, or vice versa. The upper surface of the actuating barrel (35) is provided with formations (41) adapted to engage corresponding formations (42) on the tip of a key (40). A rotatable cover barrel (45) is captivated within the open end of the bore and has an aperture (46) through which the tip of the key (40) may be passed. <IMAGE>

Description

Title - Window or Door Locking Mechanism This invention relates to a locking mechanism for windows or doors.

Windows and doors in residential and commercial properties must be capable of being locked, for security purposes. A wide variety of locking devices are used. Many such devices comprise key-operated mechanisms arranged to actuate a detent locking element which can be moved into or out of engagement with a locking recess. The locking mechanism may be enclosed within a fitting such as a handle assembly, and the recess may be formed in a base member on which the handle lever is pivotably mounted. The locking detent element then prevents pivoting movement of the handle. Alternatively, eg in the case of a sliding door, the locking recess may be provided in the window or door casement, the detent locking element directly preventing movement of the casement.

Many known designs of locking mechanism of the general type described above suffer from the disadvantage that they offer inadequate security, eg because they are capable of being opened by, for example, the blade of a screwdriver. Other, more secure devices are complex and costly. Thus, there is a need for a simple, key-operated locking mechanism for windows and doors.

According to the present invention, there is provided a keyoperated locking mechanism for a door or window, the mechanism comprising a body with a generally cylindrical bore housing a rotatable actuating barrel, rotation of the actuating barrel causing movement of a locking detent from a retracted unlocked position to an extended locking position, or vice versa, wherein the upper surface of the actuating barrel is provided with formations adapted to engage corresponding formations on the tip of a key, and there is provided a rotatable cover barrel, captivated within the open end of the bore, the cover barrel having an aperture through which the tip of the key may be passed.

The locking mechanism according to the invention is advantageous primarily in that the formations on the uppermost surface of the actuating barrel are protected, and hidden, by the cover barrel. Rotation of the cover barrel may be caused by insertion of, for example, a screwdriver blade into the aperture but this has no effect on the actuating barrel, and hence on the locking detent. Only an implement with appropriate formations at its tip can engage and rotate the actuating barrel, and thereby cause actuation of the locking detent.

The cover barrel may be generally disc-like, but preferably has a substantial depth, eg a depth comparable in dimension to its diameter, ie it is preferably generally cylindrical. The lower surface of the cover barrel lies substantially flush with the upper surface of the actuating barrel. The aperture is preferably a longitudinal slot of sufficient dimension to permit the tip of a key to be passed through the slot and to engage the formations on the uppermost surface of the actuating barrel.

The formations on the upper surface of the actuating barrel are preferably two or more recesses disposed symmetrically along a diameter of the upper surface. Most preferably, there are two such recesses, and the tip of the key is formed with two correspondingly-spaced projections.

The locking detent is preferably biassed into the unlocked position by a spring.

In a preferred embodiment, the actuating barrel is operably linked to the locking detent through interengaging cam means.

Preferably, the lower end of the actuating barrel is formed as a first cam surface and the upper portion of the locking detent is formed as a non-rotatable cam follower. The first cam surface engages and cooperates with the cam follower such that when the actuating barrel is rotated to the locking position, the locking detent is extended axially against the spring bias, and when the actuating barrel is rotated to the unlocked position the locking detent is retracted under the action of the spring.

Preferably, the first cam surface is provided by an inclined planar bottom end face of the actuating barrel extending obliquely, eg at an angle of approximately 300, to a plane perpendicular to the axis of the actuating barrel. The follower portion of the locking detent then preferably has a similarly inclined planar top face opposed to the first cam surface.

The actuating barrel may be freely rotatable such that continued rotation in one direction causes the locking detent to reciprocate between the locking and unlocked positions.

Preferably, however, rotation of the actuating barrel is restricted to an angular range of less than 3600, eg about 1800, such that the locking detent reaches the extremes of its travel when the actuating barrel is rotated to the ends of its restricted range of rotation.

The locking mechanism according to the invention may be housed in a handle unit, the locking detent being operable to prevent pivotal motion of the handle. Alternatively, eg in the case of a sliding door, the locking mechanism may be housed in a unit fixed to the window or door frame with the locking detent locating in a recess in the window or door casement.

Similarly, in the case of a hinged door or window, the locking mechanism may be housed in a unit fixed to the window or door casement with the locking detent locating in a recess in the frame.

The invention will now be described in greater detail, by way of illustration only, with reference to the accompanying drawings, in which Figure 1 is sectional view of a window casement fastener incorporating a locking mechanism according to the invention, in an unlocked position; Figure 2 is a view similar to that of Figure 1, with the locking mechanism in a locking position; and Figure 3 is an exploded view of the locking mechanism included in the casement fastener of Figures 1 and 2.

As can be seen from Figures 1 and 2, a locking mechanism according to the invention is incorporated into a window handle unit comprising a lever-type handle 1 pivotally mounted on a base plate 2. The handle unit may, for example, be fitted to the sash frame of an openable window by screws. The handle 1 may be provided with an integral latching lug (not shown) adapted to be engaged in a conventional manner with a part of the fixed frame of the window surround when the window is shut. Actuation of the locking mechanism then prevents the handle being pivoted and hence prevents disengagement of the latching lug from the window surround.

The locking mechanism is housed in a bore in the handle 1, and is shown in more detail in Figure 3. The mechanism comprises a base 31 with an aperture 32. A locking detent 33 is mounted above the aperture 32. The base plate 2 is provided with a locking recess 3 which, when the handle is in the closed position, is in registration with the aperture 32.

The stem of the detent 33 is generally cylindrical, but has a flattened side portion (not visible in Figure 3) which corresponds to a straight portion 32a of the otherwise circular aperture 32 so as to prevent rotation of the detent 33.

The detent 33 has an enlarged head portion 33a of circular cross-section. A compression spring 34 is fitted about the stem of the detent 33 and acts between the base 31 and the underside of the detent head portion 33a. The effect of the spring 34 is to bias the detent into a raised or retracted position in which the lower end of the detent 33 issubstantially flush with the aperture 32.

The upper face of the enlarged head 33a of the detent 33 is formed as a plane inclined at about 300 to the horizontal. A rotatable lock barrel member 35 has a similarly inclined lower surface. The barrel member 35 exerts a camming action on the head 33a of the detent 33, which acts as a cam follower.

Rotation of the barrel member 35 is limited by a projecting lateral lug 36 mounted on a limb 37 which is upstanding from the base 31. The lug 36 engages in a groove 38 in the side of the barrel member 35.

The barrel member 35 is rotatable between two extreme positions. In the first extreme position, the cam surfaces of the barrel member 35 and the detent 33 lie flush with one another and the detent 33 is raised. This is the position shown in Figure 1. In the second extreme position, the detent 33 is depressed by the camming action of the barrel member 35, against the action of the spring 34, such that the lower end of the detent 33 protrudes through the aperture 32 and engages in the locking recess 3. This is the position shown in Figure 2. To stabilise the mechanism in this position, the point on the upper surface of the head portion 33a of the detent 33 which contacts the underside of the barrel member 35 is provided with a flat 39. The underside of the barrel member 35 has a similar formation 39a.

Rotation of the barrel member 35 from the first to the second extreme position, and vice versa, is brought about by engagement of a key 40 with a pair of recesses 41 symmetrically disposed along a diameter of the top surface of the barrel member 35. The tip of the key 40 is formed with two projections 42 spaced and dimensioned to engage the recesses 41. A freely-rotatable cylindrical cover barrel 45 is mounted above the barrel member 35. The cover barrel 45 has a diametral slot 46 through which the tip of the key 40 may be passed. To actuate the locking mechanism, the key 40 is inserted through the slot 46 and rotated until the projections 42 engage the recesses 41. This engagement enables the barrel member 35 to be rotated from one extreme position to the other. In contrast, the barrel member 35 cannot be rotated by, for example, the tip of a screwdriver blade, since such an implement lacks suitable formations for engagement with the recesses 41 in the upper surface of the barrel member 35. Insertion and rotation of such an implement causes rotation of the freely-rotatable cover barrel 45, but has no effect on the barrel member 35 and hence cannot cause actuation of the locking mechanism.

Claims

1. A key-operated locking mechanism for a door or window, the mechanism comprising a body with a generally cylindrical bore housing a rotatable actuating barrel, rotation of the actuating barrel causing movement of a locking detent from a retracted unlocked position to an extended locking position, or vice versa, wherein the upper surface of the actuating barrel is provided with formations adapted to engage corresponding formations on the tip of a key, and there is provided a rotatable cover barrel, captivated within the open end of the bore, the cover barrel having an aperture through which the tip of the key may be passed.

2. A locking mechanism as claimed in Claim 1, wherein the cover barrel is generally cylindrical.

3. A locking mechanism as claimed in Claim 1 or Claim 2 wherein the aperture is a longitudinal slot of sufficient dimension to permit the tip of a key to be passed through the slot and to engage the formations on the uppermost surface of the actuating barrel.

4. A locking mechanism as claimed in any preceding claim, wherein the formations on the upper surface of the actuating barrel are two or more recesses disposed symmetrically along a diameter of the upper surface.

5. A locking mechanism as claimed in Claim 5, wherein there are two recesses, and the tip of the key is formed with two correspondingly-spaced projections.

6. A locking mechanism as claimed in any preceding claim, wherein the locking detent is biassed into the unlocked position by a spring.

7. A locking mechanism as claimed in any preceding claim, wherein the actuating barrel is operably linked to the locking detent through interengaging cam means.

8. A locking mechanism as claimed in Claim 7, wherein the lower end of the actuating barrel is formed as a first cam surface and the upper portion of the locking detent is formed as a nonrotatable cam follower, the locking detent being biassed into the unlocked position by a spring and the first cam surface engaging and cooperating with the cam follower such that when the actuating barrel is rotated to the locking position, the locking detent is extended axially against the spring bias, and when the actuating barrel is rotated to the unlocked position the locking detent is retracted under the action of the spring.

9. A locking mechanism as claimed in Claim 8, wherein the first cam surface is provided by an inclined planar bottom end face of the actuating barrel extending obliquely to a plane perpendicular to the axis of the actuating barrel.

10. A locking mechanism as claimed in Claim 9, wherein the follower portion of the locking detent has a similarly inclined planar top face opposed to the first cam surface.

11. A locking mechanism as claimed in any preceding claim, wherein rotation of the actuating barrel is restricted to an angular range of less than 3600 such that the locking detent reaches the extremes of its travel when the actuating barrel is rotated to the ends of its restricted range of rotation.

12. A locking mechanism as claimed in any preceding claim, which is housed in a handle unit, the locking detent being operable to prevent pivotal motion of the handle.

13. A locking mechanism for a door or window, substantially as hereinbefore described with reference to the accompanying Figures.