GB2148382A - Latching mechanism - Google Patents

Abstract

The latching mechanism is provided to lock a longitudinally movable drive element 2 for a turn-and-tilt window or door in position, when the sash or door is opened, and includes a two-arm lever 5 pivotal between a locking position and a release position. The lever 5 is mounted by a hook-like portion 12 which engages the edge of a slot 11 formed in a cover plate 1 and retained in position by means of an abutment 13 on the cover plate 1. The lever 5 is spring-urged into engagement with a slot 10 in the drive element 2 and is manually released. <IMAGE>

Description

SPECIFICATION Improvements in or relating to a locking mechanism The present invention relates to a locking mechanism, and more particularly relates to a locking mechanism adapted to lock an elongate drive element in a preselected position.

It has been proposed previously to provide mechanisms actuated by elongate drive elements which move longitudinally to cause the mechanisms to adopt various configurations. For example, reference may be made to the various mechanisms present in turn-and-tilt windows and doors. Such windows and doors are provided with an operating handle which, when it is rotated, causes various elongate drive elements present in the sash or the frame of the door to move longitudinally. The drive elements cause various bolts to be driven to positions in which they project from the sash or frame, to engage with corresponding recesses present in an outer frame, mounted securely in the structure of a building.When the handle has been operated in one predetermined manner the sash or window may be opened by pivoting the sash or door about a vertical axis adjacent one edge thereof - that is to say the sash or door can be opened in the manner of a conventional door. However, when the handle has been operated in another predetermined way the sash or door may be tilted into an open position, the sash or door then pivoting about a horizontal axis.

Finally the sash or door may be securely locked in a closed position.

It is desirable, with a mechanism of this type, to be able to lock the drive elements in position when the sash or door is in an open condition, since if the handle is inadvertently actuated, or if the drive elements move for some other reason, whilst the sash or door is in an open position, considerable damage can be done to the door and to the described mechanism.

It has thus been proposed previously to provide a mechanism for locking elongate drive elements, such as the drive elements found in a turn-and-tilt window or door fitting, in position when the sash or door is in an open position. The prior proposed locking mechanism includes a lever which is pivotally mounted on the sash or door, the lever being pivotal about an axis which is perpendicular to the plane of the sash or the door, so that the lever can be pivoted within the plane of the sash or the door. The lever carries a catch or the like which, in one position of the lever, can be inserted into a corresponding aperture or recess formed in the drive element. It is intended that the catch is to be engaged with the recess or aperture when the drive element is in a predetermined position and when the sash or door is open.A biassing means, such as a spring, is provided to bias the lever into the locking position whenever the sash or door is open. However, the device is arranged so that when the sash or door is in the closed position, the lever is moved against the said biassing means as a consequence of part of the lever engaging the frame mounted on the building, in which the sash or door is fixed, the catch thus being disengaged from the recess or aperture in the drive element. One example of an arrangement of this type is disclosed in German Utility Model Specification No. 1,915,834. The described arrangement has a complex construction because the lever, which carries the catch, is pivotally mounted on a pivot pin which is retained on a special plate, the plate being screwed to the sash or door.

The present invention seeks to provide a locking mechanism of the general type described above having a simple construction, permitting uncomplicated fitting of the locking mechanism, even to a drive element which has already been mounted in position.

According to this invention there is provided a locking mechanism to prevent incorrect or inadvertant operation of an apparatus including one or more longitudinally movable drive elements, which drive elements are displaceable into a number of actuation positions, the locking mechanism consisting of a lever which is pivotally mounted at or adjacent a central region thereof by means of a hook, formed on the lever, which is engaged in a slot formed in a carrier, one arm of the lever to one side of the pivot axis carrying a catch or abutment to be engaged, when the lever is in a locking position, with at least one locking recess or aperture in the drive element, when the drive element is in a predetermined actuation position, the other arm of the lever constituting an element that can be actuated to disengage the said catch or abutment from the locking recess or aperture in the drive element, therebeing biassing means biassing the lever into the locking position, and an abutment element associated with the carrier which coacts with an abutment on the lever directed in the opposite direction to the direction of engagement of the hook to retain the lever in position.

Preferably the said carrier consists of a cover plate behind which the said drive element is held and guided. The slot used for mounting the two-arm lever in position, which also permits the catch or abutment to be moved into and out of engagement with the drive element, may be previously formed in the cover plate, for example as a narrow slot situated on the longitudinal centreline of the cover plate. In such a way the locking mechanism can easily be fitted at any time by a simple operation, and may be removed equally simply.

Conveniently the hook provided on the two armed lever is defined by a longitudinal web projecting from the underside of the appropriate lever arm, which web passes through the said slot in the carrier, part of the web defining the said hook. If such a design is adapted, the two-arm lever may be provided with secure lateral guidance without any substantial risk of jamming.

Advantageously the abutment element associated with the carrier is constituted by a screw which is adopted to be introduced into a hole in the carrier, part of the screw then being located immediately adjacent the free end of the lever arm carrying the catch or abutment, thus preventing withdrawal of the lever from the slot. If the screw uses the abutment as a sheet-metal screw or a self-tapping screw the receiving hole in the carrier, for example in the cover plate, can be a plain hole stamped out at the same time as the adjacent slot is formed.

In one embodiment of the invention said hook is engaged with one end of the slot, and the free end of the said one arm is inserted in the slot, with the free end of the slot adjacent the end slot wall, thus preventing withdrawal of the hook from the slot, an abutment element being provided which limits the permissible pivotal angle of the lever relative to the carrier.

The said abutment element may consist of a set screw mounted on the said other arm of the two arm lever.

Alternatively the abutment element may constitute a rotatable locking pin or bolt having an offset locking projection, the locking pin or bolt being mounted on the said other arm of the lever, the arrangement being such that in one rotational position the locking projection impinges upon part of the mechanism, thus limiting the permissible tilting angle of the lever, whereas in another rotational position the locking projection enters an aperture or recess, thus not limiting the permissible tilting angle.

In all the above described embodiments the carrier for the two-arm lever may consist of a cover plate behind which the drive element provided with the locking recess or aperture is held and guided for longitudinal movement. The slot used for mounting the two-arm lever, is also used to permit entry of the catch or abutment, and is formed in the cover plate beforehand. Thus the slot is situated in the cover plate and the locking mechanism can thus at any time be fitted and removed by simple operation.

Preferably an element is provided which is connected to the two arm lever, and which projects beyond the free end of the said other arm, the projecting part carrying on actuating memberfor engagement with a fixed abutment.

Preferably the extending portion is constituted by a plate of elastically resilient material. The inherent elasticity of the plate contributes to the fact that distances of very diverse sizes between the sash frame or door frame peripheral surfaces, and the fixed frame can be bridged without difficulty and without any complicated adjustments having to be made to the locking mechanism.

Conveniently an additional supporting spring is disposed between the plate and the said one arm of the two arm lever. With such an arrangement the compensatory function can be optimised. The provision of the supporting spring is particularly advantageous if the plate has a re-adjustment facility with respect to a lever by means of a set screw or the like.

In one embodiment the element that projects beyond the end of the said one lever arm is a leaf spring, carrying at its free end the said actuating member.

In one preferred embodiment the member is formed with a guide slot to slidingly receive the leaf spring, enabling it to be mounted on the end of the leaf spring in two reversed or offset positions. The inherent elasticity of the leaf spring is preferably such that considerable differences in distance between the peripheral surface of the sash or door frame and the fixed frame, for example 12 mm, can be abridged without difficulty, and without complex adjustments being necessary. In this connection it is particularly advantageous if a gap is provided between the free end of the said other arm opposite the underside of the leaf spring, said gap widening in a wedge-like fashion towards the free end of the other arm.In such an arrangement that part of the leaf spring which supports the actuating member can automatically adjust to any differences in distance between the sash frame or door frame peripheral surface and the fixed frame over the length of this wedge-shaped gap without any appreciable increase in the spring prestressing.

Preferably the underside of the said actuating member forms an abutment which limits the permissible pivoting angle of the two arm lever. The advantage of this construction is that the two-arm lever of the locking mechanism can be fitted to the carrier simply by pushing it onto the carrier when the actuating member is removed from the leaf spring. It can then be secured against unintentional release from the carrier simply by fitting the actuating member onto the leaf spring.

Conveniently, the end of the actuating member adjacent the said one lever arm has an extension carrying a locking projection which is releasably engageable in a corresponding locking notch on the lever arm against the bias of the leaf spring. This construction facilitates reliable final fitting of the locking mechanism on the drive element cover plate.

Advantageously the locking projection engages with the locking notch after the style of a toggle joint.

Such a construction may ensure that the locking mechanism adjusts completely automatically, and without difficulty, to varying distances between the sash or door frame and the fixed frame, while enabling considerable differences in travel to be bridged.

Preferably said actuating member defines a sloping guide bevel for engagement with said fixed abutment. Where the actuating member can be pushed onto the free end of the leaf spring in two reversed or offset positions, the locking mechanism can be readily used for right-hand or left-hand operation, merely by selecting the correct orientation for the actuating member.

Preferably the said biasing means are constituted by a spring acting between the lever and the carrier.

In one embodiment the spring comprises a leaf spring, one limb of which is connected to the lever arm carrying the catch or abutment, while the other limb projects beyond the hook in the direction of the lever arm forming the actuating element, this limb engaging on the top of the carrier with a biassing force.

Preferably a transverse web is provided passing through an aperture in the leaf spring, through the two arm lever and through the member mounted on the top thereof.

Conveniently the lever is provided on one side of the drive element, and a drive mechanism is provided on the other side. The provision of the locking mechanism at this position is advantageous for various reasons. Firstly there is usually an unused space available between the sash or door frame and the fixed frame in the zone where the drive mechanism is fitted, and this enables the locking mechanism to be accommodated easily. Secondly it has been found that if the locking mechanism is located in this position, perfect operation of the locking mechanism is virtually guaranteed at all times.It is believed that one reason for this is that the manual forces effecting the opening and closing of the door or sash act on the actuating gear handle, and if the locking mechanism is located near the actuating gear handle there is a minimum risk of the door or sash twisting as the door or sash is closed. The invention also relates to a locking mechanism when mounted in the sash or door of a turn-and-tilt window or door, the locking mechanism locking the drive elements of the turn-and-tilt mechanism.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a part sectional, part elevational side view of part of a drive mechanism for a turn-and-tilt window or door incorporating a locking mechanism in accordance with the invention, the locking mechanism being shown in the locking position, Figure2 is a view corresponding to Figure 1 showing the locking mechanism in the unlocking or disengaged position, Figure 3 is an elevational view taken in the direction of the arrow III in Figure 1, Figure 4 is a part sectional elevational view showing part of a second embodiment of a drive mechanism for use in a turn-and-tilt window or door, again incorporating a locking mechanism in accordance with the invention, the locking mechanism being shown in the locking condition, Figure 5 is a view corresponding to Figure 4 showing the locking mechanism in the unlocking or disengaged condition, Figure 6 is an elevational view taken in the direction of arrow VI in Figure 4, Figure 7 is an elevational view, partly in section, showing part of a further drive mechanism for use on a turn-and-tilt window or door, again incorporating a locking mechanism in accordance with the invention, the locking mechanism being shown in the locking position, and Figure 8 is a view corresponding to Figure 7 showing the locking mechanism in the unlocking or disengaged position.

Figures 1 to 3 of the accompanying drawings illustrate, in detail, part of a mechanism provided on a sash or door of the turn-and-tilt type. A cover plate 1 which is mounted on the side edge of the sash or door, lies immediately above an elongate drive element 2. The drive element 2 is mounted in position so that it can effect a longitudinal displacement. The drive element 2 is provided with a plurality of apertures therein which engage with teeth provided on a pinion 3 which is mounted within an appropriate housing, forming an actuating gear, as is conventional. The housing is rigidly connected to the cover plate 1 and encloses part of the drive element 2. An actuating lever or handle may be used to rotate the pinion 3, thus effecting longitudinal displacement of the drive element 2.

It is intended that the drive element 2 can be moved, relatively to the cover plate 1, to adopt a number of selected different positions. In a typical example the drive element will be intended to adopt three such positions, each of which corresponds to a quite specific condition of the mechanism provided in the turn-and-tilt sash or door. For example the first position is that adopted by the mechanism when the sash or door is in the closed and locked position, the second position is that when the sash or door is capable of turning about a vertical axis, in the manner of a conventional door, and the third position is that adopted when the sash or door is capable of tilting about a horizontal axis.

As has been mentioned it is desirable, or even essential, for the drive element to be locked in position when it is in at least one of the two positions that it adopts when the sash or door may open normally the position that the drive element adopts when the sash or door opens about a vertical axis. It is preferred that the drive element is locked automatically in position as soon as the sash or door is moved out of its closed position, in the opening direction, but equally the drive element must be released, again automatically, as soon as the sash or door returns, from the open position, back to its closed position in relation to the fixed window frame. The locking mechanism 4, illustrated in Figures 1 to 3, is provided for this purpose.

The locking mechanism 4 consists of a lever 5 which is pivotally mounted at a point intermediate its ends. The lever thus has two arms, one on each side of the pivot point. The lever 5 is mounted directly on the cover plate 1 so as to be pivotal about an axis which is perpendicular to the plane of the sash or door, that is to say so that the lever can be pivoted within the plane of the sash or door. One arm 6 of the lever forms or supports an actuating element which cooperates with the fixed frame in which the sash or door is mounted when the sash or door is moved to the closed position, whilst the other arm 7 is provided with a protruding longitudinal web 8 which terminates with a catch or detent 9 which is dimensioned to cooperate with at least one locking recess 10 in the drive element 2. The recess 10 may, of course, be one of the recesses provided for engagement with the pinion 3, or may be a recess provided specifically for the purpose of engaging the catch 9.

The web 8 mounted on the lever arm 7 passes through a relatively narrow slot 11 formed in the cover plate 1, the slot preferably being formed on the longitudinal centreline of the cover plate.

In the region where the longitudinal web 8 merges with the lever arm 7, towards the central region of the leverS, the web 8 defines a hook-like portion 12 which extends towards the lever arm 6, thus defining an open recess which is open towards the lever arm 6. In assembling the described locking device, the web 8 is inserted through the slot 11, and the lever 5 is then moved towards the left, as shown in Figures 1 and 2, and the hook 12 then engages the cover plate 1 at the end of the slot 11. The engagement between the hook 12 and the cover plate 1 constitutes a pivotal connection between the lever 5 and the rest of the mechanism.To ensure that the lever 5 remains in position, that is to say to ensure that the hook 12 does not become disengaged from the cover plate 1, an abutment 13 is provided, in the form of a screw which is screwed into a hole 14 provided in the cover plate 1, the head of the screw being located in front of a part of the lever 5 which faces in the opposite direction to the direction of engagement of the hook 12. In the illustrated example the head of the screw 13 is located in front ofthe end face 15 on the lever 5, and it will be appreciated that whilst the screw is in position it is not possible to move the lever 5 in such a direction that the hook 12 becomes disengaged from the cover plate 1.The screw acting as the abutment 13 may be a sheet-metal screw or a self-tapping screw, so that the hole 14 in the cover plate 1 can be stamped out as a plain hole at the same time that the slot 11 is provided.

A biassing means 16, in the form of a coil spring (although it is to be understood that alternatively a piece of soft rubber may be used) is secured on the underside of the lever arm 6, which acts as the actuating means for the locking mechanism 4, and bears against the outside of the cover plate 1. The biassing means 16 tends to bias the lever 5 of the locking mechanism 4 into the position shown in Figure 1. In this position the catch or abutment 9 on the underside of the arm 7 is brought into engagement with the locking recess 10 of the drive element 2, as soon as the drive element 2 has been moved to a position in which a recess 10 is aligned with the catch 9 and the sash or door has been moved towards an open position relatively to the fixed frame, permitting the lever 5 to move to the position illustrated in Figure 1.Thus the drive element 2 is held in position and cannot move longitudinally.

If the sash or door is moved towards the closed position relatively to the fixed frame the lever arm 6, which is in a protruding position, engages against the fixed frame, or an abutment plate mounted on the fixed frame, and is pivoted out of the locking position shown in Figure 2 into the release position shown in Figure 3, against the action of the biassing means 16. The pivoting movement is carried out about the pivot axis defined by the engagement between the nose 12 and the cover plate 1 at the end of the slot 11. Consequently the catch or abutment 9 moves out of the aperture or recess 10 in the drive element 2, the drive element 2 thus being released.

The drive element 2 can then effect a longitudinal displacement relatively to the cover plate 1 on actuation of the pinion 3.

In the embodiment illustrated in Figures 1 to 3 an additional plate 17 is provided on the arm 6 of the lever 5. The plate 17 may be mounted in position by rivetting or by means of screws. The plate 17 consists of an elastically resilient material, such as spring steel strip or a plastics material, and is dimensioned to project considerably beyond the free end of the lever arm 6, as can be seen from Figures 1 and 2. The part of the plate 17 that projects beyond the free end of the lever arm 6 has a laterally directed inclined lug 18, which can be seen most clearly in Figure 3. The lug 18 is bent down, on one side, towards the cover plate 1.The lug 18 thus acts as a cam or bevel which, when the sash or door is moved towards the closed position, engages the fixed frame, or an abutment on the fixed frame, thus ensuring that the lever moves smoothly from the locking position to the unlocking position.

The inherent elasticity of the projecting part of the plate 17 provides the advantage that one embodiment of a locking mechanism 4 can be utilised on a wide range of windows and sashes where the distance between the door or sash frame peripheral surface to the fixed frame is within a wide limit. Thus the described locking mechanism may be used where there is only a relatively narrow gap, or where there is a relatively wide gap, without any need to alter or adjust the locking mechanism. Even if used with gaps of very different sizes, it has been found that the operational ability and reliability of the preferred embodiment of the locking mechanism as illustrated in Figures 1 to 3 is not impaired.

It is envisaged that, in certain cases, it may be advantageous to provide an additional support spring 19 between the plate 17 and the lever arm 6 which forms the actuating element, this spring 19 acting as an elastic intermediate element to optimise the force transmission from the inherently resilient plate 17tothe lever arm 6.

Although the locking mechanism described above and illustrated in Figures 1 to 3, has been found to be particularly advantageous for use in conjunction with drive element mechanisms consisting of a cover plate 1 with a drive element guided beneath the cover plate 1, this being a type of mechanism that is commonly used in conjunction with wooden or plastic sashes and doors, it has been found possible to provide a locking mechanism of the type described on drive element fittings of the kind in which the drive elements are displaceably directed in an undercut profiled groove in the sash or door.

All that is required in such cases is to fit a carrier in the form of a plate with a slot 11 in the zone where the locking mechanism 4 is to be mounted, the plate being located in front of the open side of the undercut groove. The locking mechanism can then releasably engage the drive element 2, in the manner described above, provided that the drive element 2 has appropriate recesses or apertures corresponding to the apertures 10 in the embodiment described above.

Referring now to Figures 4to 6 of the accompanying drawings a second embodiment of a drive element fitting is illustrated. In this embodiment a cover plate 1 is located above a drive element 2 which is guided for longitudinal displacement underneath the cover plate 21. An actuating gear 23 is provided, containing a pinion, as is conventional.

The casing of the actuating gear 23 is rigidly connected to the cover plate 21 and encloses the drive element 22. A rotary driving means, such as a pinion, is mounted within the actuating gear 23, the pinion meshing with the drive element 22, thus enabling the drive element 22 to be longitudinally displaced relatively to the cover plate 21 by means of an actuating handle or lever.

The drive element 22 can be moved, relatively to the cover plate 21, into a number of different positions. In a typical example the drive element 22 will be intended to be moved to three such positions, each of which corresponds to a specific position of the mechanism present in the turn-and-tilt sash or door in which the illustrated arrangement is mounted. The first such position may be the position that the mechanism adopts when the sash or door is in the closed and locked position, the second position may be that adopted when the sash or door may turn about a vertical axis for opening in a door-like fashion, and the third position may be that adopted when the mechanism is in such a position that the sash or door may open in a tilting manner about a horizontal axis.As has been mentioned, in many cases it is desirable, or even essential, for the drive element to be locked in position, at least in one of the two actuation positions outlined above normally the position associated with turning the sash or door to open in a door-like manner. The drive element should be locked in position automatically as soon as the sash or door is moved out of its closed position in the opening direction, and also the drive element must be released, automatically, as soon as the sash or door returns from the open position back to its closed position relative to the fixed frame, mounted on the building, in which the sash or door is supported. In the illustrated embodiment a locking mechanism 24 is provided to fulfill this function.

The mechanism 24 consists of a lever 25 which is mounted about a pivot axis which is located adjacent the centre of the lever. Thus the lever 25 must be considered to be a two-armed lever. The lever 25 is pivotally mounted on the cover plate so as to be pivotal about an axis which is perpendicular to the plane of the sash or door, that is to say the lever is pivotable in a plane which is parallel to the plane of the sash or door. One arm 26 of the lever forms an actuating element which cooperates with the fixed frame, or an abutment on the fixed frame, whilst the other arm 27 of the lever carries a longitudinal web 28, a protruding terminal part of which forms a catch or abutment 29 which is adapted to cooperate with at least one recess or aperture 30 provided in the drive element 22.The recess or aperture 30 may be a recess or aperture specifically provided to cooperate with the catch or abutment 29, or may be one of the recesses or apertures already provided in the drive element 22 to cooperate with the pinion present in the actuating gear 23. The web 28 is provided on the underside of the arm 27 and passes through a narrow slot 31 formed in the cover plate 21, the slot 31 preferably being formed on the longitudinal centreline of the cover plate 21.

In the region of the web 28 that is adjacent the right hand arm 26 of the lever as illustrated in Figures 4 and 5, the web 28 is provided with a recess which effectively defines a hook-like part 32 which projects towards the lever arm 26. The hook 32 can be brought into engagement with the cover plate 21, through the slot 31, the hook then providing a pivotal connection for the lever 25 to the cover plate.

The lever is retained in the engaged position, that is to say is retained with the hook 32 engaging the cover plate 21, by virtue of the fact that the edge 33 of the catch or protrusion 29 which is remote from the hook is located immediately adjacent an edge 34 of the slot 31. The angle through which the lever 25 can be pivoted is limited, relative to the cover plate, by means of a screw 35 which, after the lever has been inserted in position, is screwed into the arm 26 of the two armed lever 25 to such an extent that the end of the screw 35 projecting from the underside of the arm 26 cooperates with the outer surface of the cover plate 21, or with part of the casing of the gear 23, thus forming an abutment member which limits the angle through which the lever 25 can be pivoted.

The arrangement is such that the edge 33 of the catch 29 cannot be completely lifted out of the slot 31 in the cover plate 21, but always remains at least partially in the slot 31. Thus the face 33 is always immediately adjacent the edge 34 of the slot 31, and the lever cannot be manipulated or moved to release the hook 32 from the cover plate 21.

A biassing means in the form of a leaf spring 36 is secured to the underside of the arm 27 which carries the web 28, and the spring has a substantially "Z" shape, the spring thus comprising a fixing limb 36', a free limb 36" and a web 36" interconnecting the fixing limb and the free limb. The free limb 36" projects beyond the hook 32 in the direction of the arm 26, which forms the actuating element, the free limb 36" engaging on the outside of the cover plate 21 and the adjacent part of the casing of the gear 23, as can be seen in Figures 4 and 5.

The leaf spring 36 tends to bias the lever 25 of the locking mechanism 24 into the position illustrated in Figure 4, in which the catch or abutment 29 on the underside of the arm 27 is brought into engagement with the recess or aperture 30 in the drive element 22. The catch or abutment 29 is moved into the recess or aperture 30 as soon as the drive element 22 has been displaced so that the recess 30 is positioned to receive the catch or abutment 29 and when the sash or door is moved into an open position relative to the fixed frame. The drive element 22 is thus automatically locked against undesired displacement relatively to the cover plate, by means of the locking mechanism 24.

If the sash or door is moved into the closed position relatively to the fixed frame, the lever arm 26 of the locking mechanism 24 engages the fixed frame or an abutment on the fixed frame, thus causing the lever 25 to pivot out of the locking position shown in Figure 4 into the release position shown in FigureS, against the action of the leaf spring 36. The pivoting movement is carried out about the pivot axis defined by the hook 32 engaging the cover plate 21 at one end of the slot 31.

Consequently the catch or abutment 29 moves out of the recess or aperture 30 in the drive element 22, thus releasing the drive element 32 to permit longitudinal displacement of the drive element 22 relatively to the cover plate 21. Such movement may be effected by the actuating gear 23.

A leaf spring 37 is secured at one end thereof, for example by rivetting, to the top of the two-arm lever 25. The other end of the leaf spring 37 projects considerably beyond the end ofthe arm 26, as can be seen from Figures 4 and 5. The part ofthe leaf spring which projects beyond the arm 26 is provided with a pressure member 38 at the free end thereof.

The pressure member is provided to cooperate with the fixed frame or an abutment mounted on the fixed frame when the sash or door is closed. The element 38 is provided with a sloping or cam-like upper surface, as can be seen mostly clearly in Figure 6, to facilitate smooth operation of the described device.

To enable the element 38 to be fitted in two inverted offset positions on the free end of the leaf spring 37, for optional right-hand or left-hand operation of the locking mechanism 24, the element 38 is formed with a guide 39 having, for example a downwardly open "T" cross section. On the surface situated opposite the open side thereof, the guide is formed with a recess 40 which can cooperate with a projection 41 provided on the leaf spring 38 to enable the element 38 to be retained securely in position.

The inherent elasticity of the freely projecting part of the leaf spring 37 has the advantage that a single construction of the described locking mechanism can, without any difficulty, be utilised in situations where there is only a narrow gap between the door or sash and the fixed frame in which the door or sash is mounted, and situations where there is a relatively wide gap between the door or sash and the fixed frame in which the door or sash is mounted, without the operational ability or reliability of the locking mechanism 24 being significantly impaired.Any excessive increase in the pre-stressing of the leaf spring 37 can be obviated if the arm 26 forming the actuating element defines a gap 42 between the spring and the upper edge of the arm 26 when the spring is in the relaxed state, the gap widening substantially in the form of a wedge towards the free end of the spring. This enables the spring 37 to adopt the position illustrated in Figure 5 when the sash or door on which the described arrangement is mounted is in the closed position.

To enable the screw 35 to be accessible at all times, without being obstructed by the leaf spring 37, an aperture 43 is provided in the leaf spring 37 at an appropriate position above the wedge-shaped opening 42.

The longitudinal web 28, which carries the abutment or catch 29 is provided with an upstanding web 44 which passes through aligned, appropriately dimensioned apertures in the fixing lever 36' of the leaf spring 36, the arm 27 of the two-arm lever 25 and the leaf spring 37, and is secured, for example by way of rivets, to the top of the leaf spring 37.

It will be appreciated that the locking mechanism 24 described above and illustrated in Figures 4 to 6 of the accompanying drawings may be assembled simply and rapidly. Instead of the screw 35 being provided to retain the lever 25 in position, alternatively a locking pin or bolt or the like may be provided, which is rotatable, the locking pin or bolt having, at the lower end thereof, an offset locking projection. When the locking pin or bolt is rotated to a first position the projection will strike against the top of the cover plate 21 as the right hand end of the lever 25 is moved downwards, as shown in Figures 4 and 5, whereas when the locking pin or bolt is rotated to another position, the locking projection enters into a recess or aperture formed in the cover plate 21, thus permitting the lever 25 to be demounted from the illustrated position.

Figures 7 and 8 illustrate a further embodiment of the invention. The figures show a part of a drive element fitting, comprising a cover plate 51 and a drive element 52 mounted beneath the cover plate 51, the drive element being adapted to be driven longitudinally by means of an actuating gear 53. The actuating gear 53 includes a casing which is rigidly connected to the cover plate 51 and which also encloses a drive element 52. A rotary driving means, such as a pinion, is mounted within the casing of the actuating gear 53. The pinion may mesh with apertures provided in the drive element 52 so that, by rotating the pinion with means of an actuating lever or the like, the drive element 52 may be longitudinally displaced relatively to the cover plate 51.

The drive element 52 may be moved, relatively to the cover plate 51, into a number of different positions, for example three such positions, each of which corresponds to a quite specific actuating position of the mechanism. In the situation where the mechanism is used to actuate a turn-and-tilt window or door the first actuation position is the position in which the sash or door is locked in a closed position, the second actuation position is the position in which the sash or door may turn about a vertical axis in a door-like fashion, and the third actuation position is the position in which the sash or door may tilt about a horizontal axis.

As has been mentioned, in many cases it is desirable, or even essential, for the drive element to be locked automatically in position as soon as it reaches at least one of the two actuation positions, normally the actuation position associated with the turning of the sash or window about a vertical axis in a door-like manner, as soon as the sash or door is moved out of its closed position. On the other hand, the drive element must be released, again automatically, as soon the sash or door moves away from the open position back into its closed position in relation to the fixed window frame. In the present described embodiment a locking mechanism 54 is provided for this purpose.

Referring to Figures 7 and 8 a cover plate 51 is provided under which a drive element 52 is located for longitudinal movement. A drive gear 53 is provided containing a pinion or the like adapted to engage and move the drive element 52 when the pinion is rotated by means of a handle or the like.

The locking mechanism 54 consists of a lever 55 which is pivotally mounted substantially adjacent its midpoint, and thus the lever 55 may be considered to consist of a two-armed lever. The lever 55 is mounted on a cover plate 51 for pivotal movement about a pivotal axis which is perpendicular to the plane of the sash or door. Thus the lever 55 pivots in the plane of the sash or door. One arm 56 of the lever forms an actuating element which is intended to cooperate with the fixed window or door frame, or an abutment on the fixed window or door frame.The other arm 57 of the lever 55 carries a protruding web 58 which, in turn, carries a catch or abutment 59 intended to cooperate with at least one locking recess or aperture 60 in the drive element 52.The locking recess or aperture 60 may comprise an aperture provided in the drive element for engagement with the pinion within the drive gear 53, but alternatively the recess or aperture 60 may be provided specifically for the purpose of cooperating with the catch or abutment 59.

The said longitudinal web 58 passes through a narrow slot 51 formed in the cover plate 51, the slot preferably extending on the longitudinal centreline of the cover plate 51.

The longitudinal web is provided, at the end immediately adjacent the arm 56, with a hook-like portion 62 which projects in the direction of the lever arm 56, and which defines a recess, which is open towards the lever arm 56, this recess being capable of being brought into engagement with the edge of the slot in the cover plate 51, thus constituting a pivotal connection between the lever and the cover plate.

The lever 55 can pivot about the connection between the hook 62 and the cover plate 51 between the two positions illustrated in Figures 7 and 8. It will be noted that, in each position, a face 63 present on the left hand end of the lever arm 57 is immediately adjacent an edge 64 of the aperture 61 in the cover plate 51, and thus the lever cannot be removed from the slot. The reason for this is that the pivoting angle of the lever 55 is limited by a stop or abutment 65 which is mounted on the lever arm 56 after the lever has been mounted in position. The operation of the stop or abutment 65 can be seen from Figures 7 and 8.

A resilient biassing means in the form of a leaf spring 66 is secured to the underside of the arm 57.

The spring has a substantially "Z" shape and comprises a fixing limb 66', a free limb 66" and an intermediate connecting web 66"' between the said two limbs. The free limb 66" projects beyond the hook 62 in the direction of the arm 56, which forms the actuating element. The free limb 66" of the spring bears, with prestressing, on the outside of the cover plate 51 and that part of the casing of the gear 53 which is in the region of the spring, as will be clear from Figures 7 and 8. The leaf spring 66 tends to bias the two-arm levers of the locking mechanism 54 into the locking position as shown in Figure 7.In this position the catch or abutment 59 is biassed into engagement with the aperture or recess 60 in the drive element 52, and is held therein as soon as the drive element 52 has been displaced so that the recess 60 therein is co-aligned with the catch or abutment 59, and the sash or door is moved into an open position relative to the fixed frame. Subsequently the drive element 52 is automatically locked against unwanted longitudinal displacement. If the sash or door is then moved towards the closed position relative to the fixed frame, the lever arm 56 (or elements carried thereby) engage against the fixed frame or an abutment thereon, thus tending to pivot the lever 55 against the bias of the spring out of the locking position into the release position shown in Figure 8.The pivoting movement of the lever 55 is carried out about the hook 62 engaging beneath the cover plate 51 at one end of the slot 61. As a result of this pivoting movement the catch or abutment 59 is moved out of the aperture or recess 60 in the drive element 52, thus releasing the drive element 52 to permit longitudinal displacement thereof relative to the cover plate 51. Such movement may be effected by the actuating gear 53.

A leaf spring 67 is secured, at one free end thereof, for example by rivetting, to the top of the two-arm lever 55, The other end of the leaf spring 67 extends considerably beyond the free end of the arm 56, which forms the actuating element. The part of the leaf spring 67 which projects beyond the end of arm 56 is provided with a pressure member 68 at the free end thereof which acts as a guide surface to cooperate with the fixed frame or the abutment mounted on the fixed frame. The member 68 may have a sloping.or cam-like upper surface to facilitate operation of the described device, the surface corresponding, for example, to the sloping surface of the element 38 as shown in Figure 6.

To enable the member 68 to be releasably fitted to the free end of the leaf spring 67, it may be formed with a guide slot 69 which may, for example, have a downwardly open "T" cross section. The leaf spring may be inserted into the slot, the member 68 being slid into position along the leaf spring.

The member 68, at the end thereof adjacent the arm 56, has an extension 73 in the form of an arm with a locking projection 70 on the top surface thereof. The projection 70 is designed to engage with a corresponding a notch 71 provided on the underside of the arm 56 and the elements are designed to be interconnected, against the bias of the leaf spring 67, when the leaf spring 67 is inserted in the guide 69 and the member 61 is pushed towards the lever 55. Thus the locking projection 70 becomes snap-fastened in the locking notch 71.It is to be understood that the inherent elasticity of the freely projecting part of the leaf spring 67 not only holds the projection on the member 68 in locking engagement with the notch 71 in the arm 56, but also provides the advantage that just one construction of locking mechanism 54 can, without any problem, be utilised in many positions where there are wide or narrow gaps between the frame of the door or sash and the fixed frame in which the door or sash is mounted, without impairing the functional ability or reliability of the locking mechanism 54.

Any extensive increase in the prestressing of the leaf spring 67 can be obviated in a simple manner if the lever arm 56 forming the actuating element has an upper surface which defines a gap 72 widening, in a wedge-like manner, towards the free end thereof, with respect to the underside of the leaf spring 67 when the latter is in the completely unstressed state (see Figure 7).

Advantageously, the projection 70 is held in engagement with the notch 71 in the style of a toggle joint by means of the inherent elasticity of the leaf spring 67, in all possible operating positions of the locking mechanism 54. It will be understood that the member 68 cannot unintentionally disengage from the leaf spring 67, this being achieved in a simple manner.

When the locking mechanism is in the disengaged position, as shown in Figure 2, the underside of the member 68 acts as an abutment in cooperation with the top of the cover plate 21, and that part of the gear housing engaging overthe same, thus limiting the maximum pivoting angle of the two-arm lever 55.

Thus, as long as the member 68 is mounted on a leaf spring 67, and its extension arm 73 engages beneath the arm 56 of the lever 55, the edge 63 of the catch or abutment 59 cannot be completely lifted out of the slot 61 in the cover plate 51, but remains opposed by the front end 64 of the slot, thus retaining the lever 55 in the mounted position.

To separate the locking mechanism from the cover plate Sl,the member 68 must first be pulled away from the leaf spring 67, against the action of the inter-engaging locking means 70 and 71. Only when this step has been performed can the arm 56 of the two-arm lever 55 be pressed down sufficiently against the action of the leaf spring 67 to enable the complete lifting of the edge 63 of the catch or abutment 59 out of the slot 61 of the cover plate 51, thus enabling the hook 62 to be disengaged from the cover plate 51. Of course, to re-assemble the structure this process is reversed.

It is to be noted that the longitudinal web 58 formed integrally with the catch and/or abutment 59 is provided with a transverse web 74 which passes through the fixed limb of the leaf spring 66, through the two arm lever 55 and through the leaf spring 67, the web passing through appropriately shaped apertures, the web being rivetted to the top of the leaf spring 67.

Claims (26)

1. A locking mechanism to prevent incorrect or inadvertant operation of an apparatus including one or more longitudinally movable drive elements, which drive elements are displaceable into a number of actuation positions, the locking mechanism consisting of a lever which is pivotally mounted at or adjacent a central region thereof by means of a hook, formed on the lever, which is engaged in a slot formed in a carrier, one arm of the lever to one side of the pivot axis carrying a catch or abutment to be engaged, when the lever is in a locking position, with at least one locking recess or aperture in the drive element, when the drive element is in a predetermined actuation position, the other arm of the lever constituting an element that can be actuated to disengage the said catch or abutment from the locking recess or aperture in the drive element, therebeing biassing means biassing the lever into the locking position, and an abutment element associated with the carrier which coacts with an abutment on the lever directed in the opposite direction to the direction of engagement of the hook to retain the lever in position.

2. A locking mechanism according to claim 1 wherein the said carrier consists of a cover plate behind which the said drive element is held and guided.

3. A locking mechanism according to claim 1 or claim 2 wherein the hook provided on the two armed lever is defined by a longitudinal web projecting from the underside of the appropriate lever arm, which web passes through the said slot in the carrier, part of the web defining the said hook.

4. A locking mechanism according to any one of claims 1 to 3 wherein the abutment element associated with the carrier is constituted by a screw which is adapted to be introduced into a hole in the carrier, part of the screw then being located immediately adjacent the free end of the lever arm carrying the catch or abutment, thus preventing withdrawal of the lever from the slot.

5. A locking mechanism according to any one of claims 1 to 3 wherein said hook is engaged with one end of the slot, and the free end of the said one arm is inserted in the slot, with the free end of the slot adjacent the end slot wall, thus preventing withdrawal of the hook from the slot, an abutment element being provided which limits the permissible pivotal angle of the lever relative to the carrier.

6. A locking mechanism according to claim 5 wherein the said abutment element consists of a set screw mounted on the said other arm of the two arm lever.

7. A locking mechanism according to claim 5 wherein the abutment element constitutes a rotatable locking pin or bolt having on offset locking projection, the locking pin or bolt being mounted on the said other arm of the lever, the arrangement being such that in one rotational position the locking projection impinges upon part of the mechanism, thus limiting the permissible tilting angle ofthe lever, whereas in another rotational position the locking projection enters an aperture or recess, thus not limiting the permissible tilting angle.

8. A locking mechanism according to any one of the preceding claims wherein an element is provided which is connected to the two arm lever, and which projects beyond the free end of the said other arm, the projecting part carrying an actuating memberfor engagement with a fixed abutment.

9. A locking mechanism according to claim 8 wherein the extending portion is constituted by a plate of elastically resilient material.

10. A locking mechanism according to claim 9 characterised in that an additional supporting spring is disposed between the plate and the said one arm of the two arm lever.

11. A locking mechanism according to claim 9 wherein the element that projects beyond the end of the said one lever arm is leaf spring, carrying at its free end the said actuating member.

12. A locking mechanism according to claim 11 wherein the actuating member is formed with a guide slot to slidingly receive the leaf spring enabling the member to be mounted on the end of the leaf in two reversed or offset positions.

13. A locking mechanism according to claim 11 or 12 wherein the underside of the said actuating member forms an abutment which limits the permis sible pivoting angle of the two arm lever.

14. A locking mechanism according to any one of claims 11 to 13 wherein the end of the actuating member adjacent the said one lever arm has an extension carrying a locking projection which is releasably engageable in a corresponding locking notch on the lever arm against the bias of the leaf spring.

15. A locking mechanism according to claim 14 wherein the locking projection engages with the locking notch after the style of a toggle joint.

16. A locking mechanism according to any one of claims 11 to 15 wherein a gap is provided between the free end of the said one arm and the underside of the leaf spring.

17. A locking mechanism according to any one of claims 1 to 16 wherein said actuating member defines a sloping guide bevel for engagement with said fixed abutment.

18. A locking mechanism according to any one of claims 1 to 17 wherein the said biassing means are constituted by a spring acting between the lever and the carrier.

19. A locking mechanism according to claim 18 wherein the spring comprises a leaf spring, one limb of which is connected to the lever arm carrying the catch or abutment, while the other limb projects beyond the hook in the direction of the lever arm forming the actuating element, this limb engaging on the top of the carrier with a biassing force.

20. A locking mechanism according to claim 19 wherein a transverse web is provided passing through an aperture in the leaf spring, through the two arm lever and through the member mounted on the top thereof.

21. A locking mechanism according to any one of the preceding claims claims wherein the lever is provided on one side of the drive element, and a drive mechanism is provided on the other side.

22. A locking mechanism according to any one of the preceding claims when mounted in the sash or door of a turn-and-tilt window or door, the locking mechanism locking the drive elements oftheturn- and-tilt mechanism.

23. A locking mechanism substantially as herein described with reference to and as shown in Figures 1 to 3 of the accompanying drawings.

24. A locking mechanism substantially as herein described with reference to and as shown in Figures 4 to 6 of the accompanying drawings.

25. A locking mechanism substantially as herein described with reference to and as shown in Figures 7 and 8 of the accompanying drawings.

26. Any novel feature or combination of features disclosed herein.