FIELD OF THE INVENTION
[0001] This invention relates to a locking device, and in particular to a locking device
for a vertical sliding sash window.
[0002] Directional and orientational terms such as "top", "bottom", "upper" etc. refer to
the locking device in its normal orientation of use as shown in Fig.1.
BACKGROUND OF THE INVENTION
[0003] Vertical sliding sash windows comprising two or more window panels, at least one
of which can slide in a substantially vertical direction in use to open and close
the window, have been in long term and widespread use. A locking device is typically
fitted in order to prevent unauthorised access through the window. The locking device
for a vertical sliding sash window typically comprises a locking member mounted to
one of the window panels which can engage a keeper mounted to the other (or another)
of the window panels. When the window is closed the locking member can be moved to
engage the keeper and prevent relative sliding movement of the window panels and thereby
secure the window in the closed position.
[0004] A known locking device for a vertical sliding sash window is made and sold by the
present Applicant, under the name "Cam-Lok".
[0006] In both of these prior art devices the locking member is mounted within a housing
and can undergo limited rotation. The locking member has a curved locking element
which can project from the housing and engage the keeper, the curved locking element
being almost concentric with the axis of rotation. The lack of concentricity causes
the keeper to be pulled towards the housing as the locking member is rotated into
(further) engagement with the keeper. The keepers of both of these devices have a
slot designed to accept the locking member, the slot having a projecting tab. The
curved locking element can move around the back of the tab in the locking condition
so as to hold the locking member and keeper together.
[0007] Both of these prior devices are lockable, in that a key-operated lock is provided
which can prevent unauthorised rotation of the locking member from its engaged condition
(in which the locking member projects from the housing and engages the keeper) to
its disengaged condition (in which the locking member is retracted into the housing
and does not engage the keeper).
[0008] Also, in both of these devices the locking member is a rotatable plate, the curved
locking element of the locking member comprising a rail along the edge of the plate.
The curved locking element extends beyond the plate to form the leading end of the
locking member which is mounted in cantilever.
[0009] The presence of the plate limits the size of the tab which can project into the slot
in the keeper, as the plate lies alongside the tab in the engaged condition of the
devices. It is therefore not possible to enhance the security by increasing the size
of the tab without reducing the thickness of the plate (and thereby weakening the
locking member), and similarly it is not possible to increase the strength of the
locking member by making the plate thicker without reducing the size of the tab(s)
and making it easier to force the engaged locking member out of the keeper.
[0010] The windows of a building are known to be considered vulnerable by housebreakers
and unauthorised intruders, and are often the route by which unauthorised access is
sought to be obtained to a building. Many different types of locking devices are available
for the different window types, and the locking devices for vertical sliding sash
windows have two major disadvantages to overcome.
[0011] Firstly, because two adjacent window panels must necessarily slide relative to each
other, there must be a sufficiently large gap between them to permit relatively free
sliding movement, and that gap can often present a point of access for a housebreaking
tool. Specifically, an intending intruder will often insert a tool between the two
window panels and seek to force the locking member out of the keeper. To do this the
intruder only has to force the curved locking element past the tab, and the relatively
large gap between the window panels often allows the insertion of a sufficiently robust
tool to achieve this. The locking device for a vertical sliding sash window must therefore
be able to withstand attack from more substantial and useful tools than can normally
be used with other types of window.
[0012] Secondly, the locking device is normally mounted upon the surface of the window panel,
and in the most common case of a two-panel window the locking device will be fitted
at substantially the centre of the window. The locking device is therefore clearly
visible to most occupants of the building, and the locking device must therefore be
aesthetically pleasing and at the same time not too obtrusive, as well as functionally
robust.
[0013] Locking devices for windows are the subject of official standards in many countries.
In the UK the official standard is BS 7950. Many of the locking devices which are
presently available for vertical sliding sash windows fail to meet this standard.
[0014] There is therefore a need to provide a locking device which will meet this standard,
and this need is becoming more significant as vertical sliding sash windows take an
increasing proportion of the window market because of their pleasing appearance.
SUMMARY OF THE INVENTION
[0015] According to the invention there is provided a locking device comprising a locking
member and a keeper, the locking member being mounted for rotation in a housing, the
locking member having a curved locking element, the curved locking element being able
to project beyond the housing and into a slot of the keeper, the slot having a tab
which can be engaged by the curved locking element, the locking member having a leading
end, the locking device having a key-operated lock, characterised by a movable retainer
having an active condition in which the retainer engages and retains the leading end
of the curved locking element.
[0016] Thus, the inventors have realised that during rotation of the locking member from
its disengaged condition to its engaged condition the leading end of the locking member
is caused to move out of the housing and then back into the housing as it undergoes
its arcuate movement. The inventors take advantage of the return of the leading end
into the housing to provide a retainer which can engage the leading end and secure
the locking member against unauthorised rotation away from the engaged condition.
[0017] Preferably, the retainer is driven to its active condition by the key-operated lock.
[0018] Desirably, a part of the retainer can be located in an opening in the leading end
of the locking member. Desirably also, the retainer is a metallic rod. Usefully, the
retainer is pivotably mounted upon a boss, the retainer pivoting between its active
condition and an inactive condition.
[0019] Preferably, the tab extends across the full width of the slot. This is possible with
the present invention as the locking member does not need to be in the form of a plate
with a rail providing the curved locking element and can comprise substantially the
curved locking element alone. Without the plate being required to enter the slot the
tab can extend across the slot so as to reduce the likelihood that the locking member
can be forced past the tab by an intending intruder, and thereby to increase the security
of the locking device.
[0020] Desirably, the keeper comprises a first part and a second part, the first part including
the tab and the second part comprising a cover element. Usefully, the first part and
the second part are made of different materials, the first part being made of a material
providing the required strength for the tab, the second part being made of a material
suited to provide the aesthetically pleasing form. Preferably, the first part and
the second part together define the slot.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] The invention will now be described in more detail, by way of example, with reference
to the accompanying drawings, in which:
- Fig.1
- shows a representation of the device fitted to a vertical sliding sash window;
- Fig.2
- shows a top view of the locking device according to the invention;
- Fig.3
- shows a bottom view of the locking device, with the locking member out of engagement
with the keeper;
- Fig.4
- shows a view similar to Fig.3 but with the locking member engaging the keeper,
- Fig.5
- shows a view similar to Fig.3 but with the locking member locked in engagement with
the keeper;
- Fig.6
- shows an exploded view of the keeper; and
- Fig.7
- shows a view of the assembled keeper.
DETAILED DESCRIPTION
[0022] The locking device 10 is adapted for fitment to a vertical sliding sash window. The
locking device 10 comprises a housing 12 for the locking member 14 (Fig.3) and a keeper
16. The keeper 16 is fitted to the frame of one of the window panels 2 (in this case
the bottom horizontal frame part 4 of the upper window panel 2), and the housing 12
is fitted to the frame of the other window panel 6 (in this case the top horizontal
frame part 8 of the lower window panel 6). In known fashion, one or both of the window
panels 2,6 are mounted for vertical sliding movement in channels (not shown), so that
in use (when the locking device is in its disengaged condition) the window panels
2,6, and the respective keeper 16 and housing 12 can slide vertically relative to
one another.
[0023] As above indicated, the locking device 10 will typically be clearly visible to the
occupant of the building, and is therefore made aesthetically pleasing in front view.
In particular, the visible parts of the housing 12 and keeper 14 are of cooperating
form and matching surface finish. (In Fig.1 the frame parts 4,8 are shown in dotted
outline and the mounting flange 18 would not be visible when the window is closed).
[0024] The housing 12 has an opening through which projects a boss 20 (Fig.3). To the top
of the housing 12 the boss 20 carries an operating handle 22, and to the bottom of
the housing 12 the boss 20 carries the locking member 14. In this way, the operating
handle 20 and the locking member 14 are mounted to move together, and in particular
to rotate together upon or around the boss 20.
[0025] The locking member 14 is therefore mounted for rotation relative to the housing 12.
As shown in Figs. 3,4 and 5 the locking member 14 can be rotated (by way of the operating
handle 22) between the disengaged condition of Fig.3 (in which the curved locking
element is wholly within the housing), and the engaged condition in Figs. 4 and 5
(in which a large part of the curved locking element 24 projects beyond the housing
14 and into the keeper 16).
[0026] The locking member 14 has a curved locking element 24 which is substantially concentric
with the rotational axis of the locking member 14, i.e. with the central axis of the
boss 20. Ideally, however, the inner surface 26 of the curved locking element 24 converges
towards the rotational axis from its leading end 30. This convergence provides a "camming"
action for the locking device, in known fashion. In addition, the curved locking element
24 can taper in the vertical plane so as to provide a camming action also in the vertical
direction if required.
[0027] The keeper 16 is shown in more detail in Figs. 6 and 7. The keeper has a slot 32
and a tab 34 which spans the slot 32. It will be understood that as the operating
handle 22 is rotated from the disengaged condition shown in Fig.3 to the engaged condition
shown in Fig.4, the leading end 30 of the locking member 14 is caused to project from
the housing 12 and to enter the slot 32 to one side of the tab 34, pass around the
tab 34 and pass back through the slot 32 to the other side of the tab 34, finally
re-entering the housing 12. Accordingly, in the engaged condition shown in Fig.4 the
locking member passes around the tab 34 and thereby secures the housing 12 and keeper
16 together.
[0028] It will be observed that the tab 34 is curved slightly so as match the curvature
of the inner surface 26 of the curved locking element 24, and also that the inner
surface 26 has a small flattened region 36 which engages the tab 34 in the engaged
condition of the locking member 14.
[0029] Though not shown in the drawings, adjacent to the leading end 30 the locking member
14 has an opening which can accommodate a part 40 of the retainer 42. In this embodiment
the opening is an aperture through the leading end 30 of the locking member 14, but
in other embodiments the opening is a recess or blind hole in the leading end. The
retainer 42 is a formed metal rod and is mounted upon a boss 44 of the housing 12.
The housing 12 also carries a stop 46 for the retainer 42, and a raised button 50
providing a detent for the retainer 42.
[0030] The boss 20 of the housing 12 also mounts a key-operated lock 52. The key-operated
lock 52 is connected to an actuator 54 which can engage the retainer 42. The key-operated
lock normally rotates with the operating handle 22, so that the actuator 54 normally
rotates with the locking member 14. Accordingly, unless the lock 52 is actuated the
actuator 54 will rotate with the locking member 14 between the disengaged and engaged
conditions shown in Figs. 3 and 4 respectively.
[0031] When it is desired to lock the locking device 10 in the engaged condition, i.e. to
lock the keeper 16 to the housing 12, the correct key is inserted into the lock 52
and the key rotated relative to the operating handle 22. This causes the actuator
54 to rotate relative to the locking member 14, and specifically to rotate in a clockwise
direction from the position shown in Fig. 4 to the position shown in Fig.5. During
this movement, the actuator 54 engages the retainer 42 adjacent to the part 40 and
drives the retainer 42 to rotate anticlockwise as drawn, past the button 50, and to
drive the part 40 into the aperture in locking member 14, as shown in Fig.5.
[0032] In the engaged and locked condition of Fig.5 one end of the locking member 14 is
secured to the housing 12 by way of the retainer 42, whilst the other end of the locking
member is secured to the housing 12 by way of its mounting upon the boss 20. The locking
member 14 is therefore secured to both sides of the tab 34. This permits the locking
member 14 to avoid the requirement for the strengthening plate present in the prior
art devices, and thereby permits the tab 34 to span the full width of the slot 32
(though it will be understood that the strengthening plate can be used in other embodiments
if desired).
[0033] When it is desired to unlock the locking device 10 the key is rotated in the opposite
direction which drives the actuator to move anticlockwise as drawn in Fig.5 to its
position shown in Fig.4. It will be seen that the retainer 42 has a leg 56 which is
engageable by the actuator 52, anticlockwise rotation of the actuator 52 driving the
retainer 42 to pivot clockwise as drawn, past the button 50, and thereby releasing
the part 40 from the aperture in the locking member 14. Thereafter, the operating
handle 22 can be rotated to move the locking member to its disengaged condition.
[0034] It is a particular advantage of the present invention that the lock 52 can be carried
by the boss 20 for the operating handle 22, as this minimises the volume of the housing,
avoids the need for a mechanical link to be made between the lock and the locking
member, and provides an aesthetically pleasing housing. The provision of a lock upon
the boss of the operating handle has not generally been preferred as an intending
intruder can seek to disable the lock by applying force to a locked operating handle.
With the present invention, however, it is not possible to remove the part 40 of the
retainer 42 from the aperture in the locking member 14 without correct operation of
the lock, and force transmitted to the operating handle, even if that is sufficient
to break the operating handle or the internal lock components, will not release the
retainer, nor therefore release the locking member.
[0035] The preferred form of keeper 16 is shown in Figs. 6 and 7. The keeper 16 comprises
a first part 60 and a second part 62, which parts are connected together in the assembled
keeper. Making the keeper 16 in two parts allows the most suitable materials to be
used for each part. In particular, the first part 60 which includes the tab 34 must
be sufficiently strong to withstand the forces expected to be applied by an intending
intruder. The first part 60 is ideally a steel pressing. The second part 62 is the
only part which is visible when the keeper is mounted upon a window panel and the
window is closed (Fig.1), and requires much less mechanical strength than the first
part 60. The second part 62 can therefore be made of a less rigid material such as
a die-cast metal, and have a form and surface finish to match the housing 12.
[0036] The second part 62 has two mounting holes 64 therethrough for receiving fixing screws
or the like (not shown), and the first part 60 has two aligned holes 66 (only one
of which is partially visible in Fig.6). The second part 62 also has two formed lugs
70 which can be located into aligned holes 72 in the first part 60. In the assembled
keeper of Fig.7, the lugs 70 have been deformed into rivets to secure the two parts
60,62 together. When the keeper 16 is mounted to the window the rivets are supplemented
by the fixings passing through the holes 64 and 66, so that there are four fastenings
holding the two parts 60, 62 together and the keeper 16 is substantially rigid.
1. A locking device (10) comprising a locking member (14) and a keeper (16), the locking
member being mounted for rotation in a housing (12), the locking member having a curved
locking element (24), the curved locking element being adapted to project from the
housing and into a slot (32) of the keeper, the slot having a tab (34) which can be
engaged by the curved locking element, the locking member having a leading end (30),
the locking device having a key-operated lock (52), characterised by a movable retainer (42) having an active condition in which it retains the leading
end of the curved locking element
2. A locking device (10) according to Claim 1 in which the retainer (42) is driven to
its active condition by the key-operated lock (52).
3. A locking device (10) according to Claim 1 or Claim 2 in which a part (40) of the
retainer (42) is adapted to locate in an opening in the leading end (30) of the locking
member (14).
4. A locking device (10) according to any one of Claims 1-3 in which the retainer (42)
is a metallic rod.
5. A locking device (10) according to any one of Claims 1-4 in which the retainer (42)
is pivotably mounted upon a boss (44), the retainer pivoting between its active condition
and an inactive condition.
6. A locking device (10) according to Claim 5 in which the housing has a detent (50)
adapted to hold the retainer (42) in its inactive condition.
7. A locking device (10) according to any one of Claims 1-6 in which an actuator (54)
is connected to the key-operated lock (52), the actuator being adapted to engage the
retainer.
8. A locking device (10) according to any one of Claims 1-7 in which the tab (34) extends
across the full width of the slot (32).
9. A locking device (10) according to any one of Claims 1-8 in which the keeper (16)
comprises a first part (60) and a second part (62), the first part including the tab
(34) and the second part comprising a cover element.
10. A locking device (10) according to Claim 9 in which the first part (60) and the second
part (62) are made of different materials
11. A locking device (10) according to Claim 9 or Claim 10 in which the first part (60)
and the second part (62) together define the slot (32).