Source: http://www.allindianpatents.com/patents/200930-a-door-locking-device-and-a-door-latch-mechanism
Timestamp: 2018-07-21 07:53:43
Document Index: 12261530

Matched Legal Cases: ['art 6', 'art 6', 'art 6', 'art 6', 'art 6', 'art 6', 'art 6', 'art 6', 'art 6', 'art 6', 'art 6', 'art 57', 'art 60']

Indian Patents. 200930:A DOOR LOCKING DEVICE AND A DOOR LATCH MECHANISM
A DOOR LOCKING DEVICE AND A DOOR LATCH MECHANISM
A locking device (1)for a door latch mechanism having a latch bar (18) turnable to retract a latch bolt of the door latch mechanism by turning either of two door handles (3) coupled to opposite ends of the latch bar is characterised by coupling Imeans (4,17,19) for coupling an associated door handle (3) to the latch bar for turning; the latch bar when the coupling means is turned in one direction and turnable I relative to the latch bar in the opposite direction, locking means (20,26) to prohibit turning of the latch bar (18) by one of the door handles (3), and cam means (6) for controlling actuation of the locking means (20,26), the cam means and locking means being able to turn relatively to one another in response to relative turning movement of the coupling means and latch bar so that the locking means is actuated in response to turning of the other door handle (3) in one direction, whereafter the locking means is releasable by turning the other door handle in the opposite direction.
" A DOOR LOCKING DEVICE AND A DOOR LATCH MECHANISM"
This invention relates to a door locking device and a door latch mechanism.
The present invention particularly relates to locking devices for door latches of the type which may be released to enable opening of a door by turning one of the 5 associated door handles on opposite sides of the door. The locking device enables the latch to be locked in its latched position from one side of the door and prohibits the door from being opened by turning of the handle on the opposite side.
Door latches are used to retain closures such as doors and gates in closed positions and, typically, comprise a spring loaded latch bolt which is resilientty urged outwardly of the 10 latch into a latching position in which it is engageable with a retainer or catch on an adjacent door frame to latch the door in its closed position. The latch is retracted in order to permit opening of the door by turning of a square section bar which projects from opposite sides of the latch and the door and which may be turned by handles fitted to opposite ends of the bar. The handles may be knobs or lever arms. If a door having such a latch
15 mechanism is to be locked in its latched position, the latch normally incorporates a separate i key-operated bolt or, alternatively, one or both latch handles may be fitted with a complicated central locking mechanism actuated by a central push button or tumable member.
US-A-1688240 comprises a spring loaded latch bolt which is resiliency urged
20 outwardly to engage a catch in the door jamb and which is retractable in response to turning of either of a pair of coaxial latch bars, each fitted with a door knob. To lock the door from the inside, when it is closed, the inside door knob is turned in either direction. This knob is coupled by its latch bar to a cam which, in response to turning of the knob, pushes a locking member mounted on the latch bar, within the latch mechanism, so
25 that a part of the locking member engages a slot in the housing of the mechanism. When engaged with the slot the locking member prevents the other latch bar from turning so that the outside door knob cannot be turned. Hence, the door
cannot be opened from the outside. To release the outside knob, the inside knob must f;rst be turned to retract the latch bolt and this enables the door to be opened. When the door is opened, the inside knob has to be released by the user to enable the spring loaded boit to extend beyond the door, 5 whereupon the latch bolt pulls the locking member from the slot,thus releasing the outside door knob.
US-A-5433495 also discloses a door latch mechanism within a body of a door, comprising a latch bolt whicn is retractable in response to turning of a door knob en either side of the doer. One of the knobs is designed to be
10 pushed in towards the door to prevent the latch bolt from being retracted by either knob. To enable the door knobs to be able to subsequently retract the latch bolt, the same door knob is then pulled out.
CH-A-565307 discloses a sash window with a crank handle and a spring biased lock.
15	An object of the present invention is to provide a locking device for the
latch bolt of a door latch mechanism, which device may be actuated by a turning action of the door handle also used to retract the latch bolt for opening of an associated door.
20 locking device for use with a door latch mechanism in which the door latch mechanism has a latch bar which is turnable to retract a latch bolt of the door latch mechanism by turning of a door handle at either end of the latch bar, the locking device being characterised by
locking means adapted to be actuated to prohibit turning of the latcn
2 5 bar and retraction of the latch bolt, and
cam means for controlling the locking means and adapted to be coupled to the latch bar, whereby the locking means is actuated by turning of the cam means in response to Turning of one of the door handles of the door latch mechanism in one direction, whereafter the locking means is releasable by
30 turning of the cam means in response to turning of said one door handle in the
/C*:
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Preferably, the cam means is coupled to the latch bar by coupling means enabling the cam means to turn relatively to the latch bar, when turned in said one direction. The coupling means may comprise a passageway in the 5 cam means for fitting the cam means to the latch bar, said passageway having an internal profile which enables the cam means to turn through a limited arc of movement relative to the latch bar, when turned in said one direction.
The locking means may comprise first means turnable with the latch
10 bar and second means which is engaged" with the first means to prohibit turning of the latch bar in response to turning of the cam means in said one direction, and which is disengaged from the first means by turning the cam means in the opposite direction.
In one embodiment, the second means comprises a slidable locking
15 member controlled by the cam means. The first means may comprise a detent, and the slidable locking member may be engagable with the detent to prohibit turning of the latch bar. The detent may be disposed on a rotatable locking member adapted to be mounted on the latch bar so as to turn therewith.
20	It may be desirable for the cam means to be profiled to prevent the
siidable locking member from engaging the first means when the cam means is turned in said opposite direction whilst permitting the slidable locking member to engage the first means when turned in said one direction. The cam means may have a recess which permits the slidable locking member to
25 move into engagement with the first means, said recess having a stop portion at one end which prevents the cam means from turning further in said one direction upon engagement of the locking member in the recess, and a ramp portion at its opposite end to ease the locking member from the recess when the cam means is turned in the opposite direction.
30	The locking device may include a door handle with the cam means
A o. .1 c M n c n.
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integral with the handle. Conveniently, the handle is rctatably mounted in a housing adapted to be secured in a fixed position relative to the door latch mechanism. The second means may be mounted in said housing.
The coupling means of the locking device may comprise a first part in
5 the cam means and a second part turnable with the latch bar which the first
part is adapted to engage, the cam means being able to turn through a
limited arc of movement relative to the latch bar when turned in said one
direction, when the coupling parts are disengaged.
The locking device may have indexing means for indexing the door
10 handle alternatively in either of two positions in one of which the latch bar is
prohibited from turning, and in the other of which the latch bar is free to
According to this aspect of the present invermon Ibfite is provided an auxiliary lockin_q_rij£yic£, which may be fitted to an existing latch. In this
15 case, the locking device with a handle is fitted in place of one of the original latch handles in order to provide The latch with a locking facility, so that a door can be locked from one side and cannot be opened by turning the latch handle attached to the latch bar on the opposite side of the door.
According to another aspect of the present invention there is provided
20 a door latch mechanism comprising a latch bolt which is retractable in response to turning of a latch bar, characterised by locking means adapted to be actuated in response to turning of a door handle fitted to the latch bar to prohibit retraction of the latch bolt by turning of a handle on the opposite side of the door, whereafter the locking means is releasable by turning said
25 one handle in the opposite direction.
The locking means of the latch mechanism may be adapted to be actuated to prohibit turning of the latch bar, and include cam means for controlling the locking means, which cam means is coupled to the latch bar, whereby the locking means is actuated by turning of the cam means in
30 response to turning of said one door handle in one direction, and the locking
07-2001	GBCC01S20
means is rsieasable by turning of the cam means in response to turning of said cne door handle in the opposite direction.
In one embodiment, the cam means cf the latch mechanism is coupled to the latch bar by coupling means enabling the cam means to turn relatively 5 to the latch bar, when turned in said one direction, the coupling means comprising a passageway of rectangular cross-section in the cam means by which the cam means is coupled to the latch bar and wherein the latch bar has an external profile which enables the cam means to turn through a limited arc cf movement relative to the latch bar, when turned in said one
IC direction.
In another embodiment, the latch mechanism may include first and second coaxial latch bars for projecting from opposite sides of the door, the locking means comprising actuating members on said latch bars, the actuating members being engageable with the latch bolt, whereby at least one of the
15 latch bars is rotatable in said one direction to cause rts actuating member to engage the latch bolt and prohibit retraction thereof by turning of the other
latch bar.
2	0	Figure 1 is a plan view of one embodiment of the invention;
Figure 2 is a rear elevational view taken along lines 2-2 of Figure 1;
Figures 3 and 4 are sectional views taken along fines 3-3 and lines 4-4 cf Figure 2 respectively;
Figures 5 to 12 illustrate details of the locking device;
25	Figures 1 3 to 16 illustrate alternative details;
Figures 17 and 18 are details of another embodiment of the invention;
Figure 19 is a plan view of yet another embodiment of the invention;
Figures 20 and 21 are sectional views taken aiong lines 20-20 and lines 21-21, respectively, of Figure 19;
3	0	Figure 22 is a plan view of the locking device of Figure 19 shown in its
3-07-2001 G30C01920
Figures 23 and 24 are sectional views taken along lines 23-23 and lines 24-24, respectively, of Figure 22;
Figure 25 is a plan view of the locking device of Figure 19 shown in its 5 locked position; and
Figures 26 and 27 are sectional views taken along lines 26-26 and lines 27-27, respectively, of Figure 25.
The locking device 1 illustrated in Figures 1 to 16 of the accompanying drawings is designed for fining to the latch bar of a door latch inset within the 10 body of a door between opposite sides of the door. The latch bar is of square cross section and projects from opposite sides of the door and a normal door
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handle is fixed to the end of the latch bar at one side of the door and the locking device is fitted to the end of the latch bar on the opposite side to permit the door to be locked from that side. As is conventional, the latch includes a spring loaded latch bolt which is resiliency urged into a projecting 5 position for engaging a catch on the door frame so as to latch the door in a closed position. The latch bar is coupled to the latch bolt by a conventional latch mechanism which operates to retract or withdraw the latch bolt into the latch casing and disengage it from a cooperating door catch, in response to turning of the latch bar. so as to permit the.door to be opened.
10	Referring to Figures 1 to 12, the locking device 1 comprises a cast
metal housmq or escutcheon 2 .in which is journalled a door handle 3. This door handle comprises a generally conical body 4 from the outer end of which projects a lever arm 5 by which the handle may be manually turned. The opposite end of the body 4 has a cylindrical part 6 of reduced diameter
15 compared to the diameter of the adjoining pan of the body. This reduced diameter part 6 projects into the housing 2 through a suitable hole m the housing and is journalled in an annular collar 7 projecting from the housing, about the hole, by means of a sleeve 8 (see also Figure 8). The sleeve has an annular flange 9 projecting between and in abutting relation with both the
20 free end of the collar 7 and the body 4. It is prevented from turning tn the collar by grooves 10 of the sleeve 8 engaging cooperating ribs 11 (Figure 12) projecting from the inside of the collar 7. The sleeve has first and second pockets 12.13 spaced circumferentially about its inner periphery for encaging a dome shaped detent 14 mounted in the cylindrical part 6 of the
25 handle for indexing the handle in the rest and locked positions, respectively.
The detent is mounted in a socket 1 5 (Figures 4 and 7} in the cylindrical
part 6 and is spring biassed towards the surrounding sieeve 8. The handle 3
is secured to the housing 2 by means of a circlip 1 6 fitted to the cylindrical
part 6 of the body 4 and abutting the inside of the housing.
30	The handle body 4 has a blind passageway 17 extending into the
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body from trie inner end thereof opposite the lever arm 5 and fitting onto the adjacen; projecting end 0: the latch bar 18 (shown in chain dotted lines on Figure 5). The passageway 17 has an internal profile formed from specially designec longitudinally extending ribs 19 which are arranged so as to enable :¦ the handle to engage ana turn tr.e square section latch bar, when the handle is turned in a clockwise direction from the rest position, and enable the handle to turn relative:-/ to the latcn bar when the handle is turned in an anticlockwise direction from the rest position.
Disposed m the housing 2, adjacent the inner end of the part 6 of the
10 handle bcdy 4. is an annular cam or locking bush or member 20 (see also
Figure 9) which has a collar 21 projecting from its end opposite the part 6
and journalled in a suitable hole in a base plate 22 attached to the housing 2.
The locking bush is rotatabie relative to the housing and base plate and has
a central, square aperture 23 for engaging the latch bar and a locking notch
15 or recess or detent 24 in its periphery.
Cast en the inside of the housing 2, adjacent its periphery, is a locking bar guide 25 (see Figures 10 and 1 1) which is in the form of a channel that is radially disposed to the axis of rotation of the handle 3. The guide mounts a locking bar or member 26 which is shdable radially in the channel ana is
2C spring biased towards the locking bush 2u and the cylindrical pan 6 of the
handle body A. The locking bar includes a protrusion 21 which is slidable in a
guide slct 2S in the tase plate 22 and aligned with the locking bar guide 25.
The inner end of the cylindrical part 6 has a cam surface formed on its
periphery for controlling movement of the locking bar. At its radially inner
25 end the locking bar has a cam follower portion 30 in engagement with the cam surface and the latter includes a camming recess 31 which, when the handle 3 and cylindrical parr 6 are turned to a predetermined locking position, permits the locking bar to clip into engagement with the notc.h 24 in the locking bush 20. One end 32 of the camming recess serves as a stop
30 which engages the cam follower portion 30 of the locking bar 26 to prevent
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further turning of the cylindrical par: 6 and handle 3 once the locking bar is engaged with the notch 24 in the locking bush 20 and the opposite end 33 of the camming recess is inclined cr ramped to facilitate disengagement of the locking bar from the notch when the handle is turned in the opposite z direction.
The housing 2 of the locking device 1 is attached to one side of a door by means of screws, with the passageway 17 of the handle body 4 engaged with the latch bar 18. Holes 34 are provided through the wall cf the housing and in the base plate 22 for these screws.
10	The handle 3 maybe a JPS Raven handle or equivalent. The housing 2
may be a zinc alloy coating, the sleeve 8 may be of nylon and the detent 14 may be of brass. The base plate 22 may be stamped from steel plate and may have a thickness of 1.5mm.
When the handle 3 of the locking device 1 is in its rest position shown
15 in Figure 2, the locking bar 26 is aligned with the notch 24 in the locking bush 20 but is prevented from being urged into engagement with the notch by the cam surface on the cylindrical handle part 6. In this position, the detent 1 4 engages the first pocket 1 2 in the sleeve 8. to index the handle in its rest position.
2C	To open a door fitted with the locking device 1, the lever arm 5 of the
handle 3 is turned in a clockwise direction from its rest position, when viewed from the front. When turned in this direction, the ribs 19 of the handle body 4 couple and engage the square section of the latch bar 1 3 so that the latter turns with the handle and, hence, the latch bolt is retracted
25 allowing the door to be opened. At the same time, the locking bush 20 also rotates with the latch bar. The turning of the handle body 4 causes the detent 14 to disengage from the first pocket 12 in the sleeve 8. When the lever arm 5 is released, the latch bar turns under the action of the latch spring in an anti-clockwise direction causing the handle 3 and locking bush
30 20 to return to the rest position where the detent 14 re-enters the pocket 12
8 to index the handle in this rest position.
To lock the door, the handle 3 is lifted upwardly from its rest position, in an anticlockwise direction. In this direction of rotation, because of the design of the ribs 19, the
5	handle tums relatively to the latch bar 18 and locking bush 20. The turning of the handle
causes the detent 14 to disengage from the first pocket 12. As the handle body 4 rotates, the camming recess 31 moves into contact with the cam follower portion 30 of spring loaded locking bar 26 enabling the latter to fall into engagement with the notch 24 in the locking bush 20 which, in the indexed rest position of the handle, is aligned with the locking bar 26
10 thereby locking the latch bolt in its extended position. As the door locks, the detent 14 engages the second pocket 13 to index the handle in this locked position. Further anticlockwise movement of the handle is positively prevented by the cam follower engaging the stop side 32 of the cam recess 31. The latch bar 18 is, thus, firmly locked against turning, preventing operation of the latch from the opposite side of the door. The door is thus locked.
15 Returning the handle clockwise to its rest position reverses the movement described above. The inclined side 33 of the camming recess 31 eases the locking bar 26 radially outwardly from the body 4 in response to the latter being turned and causes the locking bar to disengage from the locking bush 20, thereby releasing the latch bar so that it can be turned from the opposite side of the door.
20	In a modification shown in Figure 13 (which is similar to Fig. 7), the passageway 17
in the cylindrical part 6 of the handle has an internal profile formed from an alternative arrangement of longitudinally extending nbs 61 .
In another modification shown in Figures 14 and 1 5, the locking device includes a dog clutch 35 having two halves 36,37. The first clutch half 36 has a square shaped aperture
25 38 and the latch bar engages within the aperture so as to couple the first clutch half to the latch bar. This first clutch half replaces, or is fixed to, the locking bush 20. The second clutch half 37 is attached to the inner end of the handle body and has a circular shaped
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aperture 39 through which the latch bar freely projects. The latch bar is also freely rotatabie within the handle body passageway.
Each half of the clutch has a pair of lugs 40 which respectively abut against the lugs 40 in the opposing clutch half when the locking device is in 5 its rest position. When the handle is turned clockwise from its rest position, the engaged lugs cause both halves 36,37 of the clutch to rotate, which turns the latch bar 18 to retract the-latch bolt. When, however, the lever arm is turned anti-clockwise from the rest position, the pairs of lugs are disengaged, thereby allowing the handle to turn relative to the latch bar and the locking
1C block to move into locking relation with the latch bar under control of the cam member.
In yet another modification shown in Figure 16, the locking device includes a circular plate 41 which has a pair of opposing arcuate slots 42 engaged by a pair of pegs 43. The circular plate has a square shaped aperture
15 44 within which the latch bar 18 engages so as to couple the circular plate to the latch bar. This circular plate replaces, or is fixed to, the locking bush 20 of the first embodiment. The pegs project from the inner end of the handle body which is freely rotatabie relatively to the latch bar. When the handle is turned clockwise from the rest position, the pegs are forced against the ends
20 of the arcuate slots 42, causing the latch bar 18 to rotate. When, however, the handle arm is turned anti-clockwise from the rest position, the pegs travel freely along the slots enabling the handle to turn relative to the latch bar.
An advantage of the above described embodiment is that the locking device can be easily attached to one side of a door, replacing any existing door
2 3 handle arrangement on that side of the door. The door handle arrangement on the other side of the door need not be changed. The locking device does not require a receiving cavity to be chiselled into the body of a door between opposite sides of the door or any other form of carpentry work to be performed.
30	Moreover, the operation of the locking device is simple. With the door
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closed, the handle of the locking device is Turned upwards, for example, through 45° and this locks the latch bar extending through the door and,, hence, the latch. The door cannot then be opened from the opposite side. However, in the case of emergency, such as a fire, the door is simply and 5 quickly opened by the normal method of pulling the handle down. Practical tests have shown that it is far quicker to operate than any other form of lock, whether this be a key or bolt, and there is no fumbling in the case of panic as it is the natural way to open the door.
In a second embodiment shown in Figure 1 7, the cylindrical part 6 of
10 the handle has a blind, rectangular section passageway 62 extending into the handle body for fining to the latch bar 63 which has an external profile defined by the bar being hexagonal in cross-section. This enables the handle to engage and turn the latch bar 63, when the handle is turned in a clockwise direction from the rest position, and enables the handle to turn relatively to the
15 latch bar when the handle is turned in an anti-clockwise direction from the rest position.
In a modification shown in Figure 18 to the second embodiment, the hexagonal section latch bar has been replaced by a latch bar 64 which has an external profile defined by the bar being "S" shaped in cross-section.
20	Figures 19 to 27 illustrate a third embodiment of the invention which
essentially consists in a modified door rim latch very similar to those in current use and which is intended to be inset within the body of a door between opposite sides of the door. In this embodiment, instead of a latch bar of square cross section extending through the latch and the door, the
2 5 latch bar is split into first and second coaxial latch bar members 44,45 each projecting from one side of the door and having a lever door handle 46,47 fitted thereto for turning the latch bar member. The two handles are suitably journalled and operate independently of one another. The latch includes a latch bolt 48 which is resiliency urged into a latching position by a
^0 compression spring 49. The latch bolt has a hollow latch body 50 formed as
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a pressing and having a solid nose 51 for engaging a cc-cperatmg catch on the dcor frame. The latch bar members project into the latch body and each member has a cam 52,53 attached to its end projecting into the body. These cams control movement of the latch bolt and each cam has an acurate flange 5 54,55 projecting from the cam about part of its circumference. The cam flanges are arranged to engage a slot 56 in the top part 57 of the body 50 of the latch bolt and, in the rest position illustrated in Figures 19, 20 and 21, where the latch bolt is urged into engagement with its co-operating catch by the compression spring 49, the radial edges of the flange are in contact with
10 the body 50 and the handles are horizontal. The cam flange associated with at least one of the handles is formed with an additional lug 58 at the peripheral end of the flange opposite that engagable with the end of the slot 56 which, when the latch bolt is in its extended, latching position can engage with a co-operating slot 59 in the bottom part 60 of the latch body. When the
15 latch is in its latching position, turning of the relevant latch handle 46 or 47 in an anti-clockwise direction moves the associated cam flange 52,53 so as to engage the lug 53 with the slot 59 and prevents the latch bolt from being retracted.
Hence, if either handle is turned, for example, through 45°, in this
20 case, downwardly from the rest position, either cam operates the latch, by means of its acurate flange actuating the latch body, and opens the latch bolt 50 in a normal manner, as shown in Figures 22, 23 and 24. However, if the handle with the locking iug is moved through 453 anti-clockwise from the rest position, its cam lug 58 engages in the slot 59 in the bottom of the
2 5 latch body, as illustrated in Figures 25, 26 and 27, and prevents the latch from being retracted if any attempt is made to move the other door handle. The dcor is thus locked. The non-locking side of the door has a handle which will not move from the horizontal position in an anti-clockwise manner so that a door can only be locked from one side.
30	Whilst particular embodiments have been described it will be
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understood that various modifications may be made without departing from the scope of the invention as defined by the appended claims. For example, the locking device could be easily adjusted to be operated by a left-handed lever arm instead of a right-handed lever arm. The direction of rotation of the 5 lever arm can be reversed to lock or open the door respectively. The lever arm may be replaced by a knob. The components of the locking device may be made of any suitable material. In the last described embodiment, a catch may be used to retain or index the first handle in place in order to lock the door from the opposite side. 10
13 WE CLAIM-
1 A locking device (1) for use with a door latch mechanism having a latch bar (18) which is turnable to retract a latch bolt of the door latch me.chanism by 5 turning either of two door handles (3) coupled to opposite ends of the latch bar, the locking device being characterised by
coupling means (4,17,19) for coupling an associated door handle (3) to
the latch bar, said coupling means being adapted to couple the associated
handle to the latch bar for turning the latch bar when the coupling means is
10 turned in one direction and said coupling means being turnable relatively to the
latch bar in the opposite direction,
locking means (20,26) adapted to be actuated so as to prohibit turning of the latch bar (18) by one of the door handles (3), and
cam means (6) for controlling actuation of the locking means (20,26), said 15 cam means and locking means being able to turn relatively to one another in response to relative turning movement of said coupling means and said latch bar so that the locking means is actuated in response to turning of the other door handle (3) in one direction, whereafter the locking means is releasable by turning said other door handle in the opposite direction. 20
2. A locking device as claimed in claim 1, wherein the coupling means comprises a passageway (17) for fitting to the latch bar (18), said passageway having an internal profile (19) which enables the coupling means to engage the latch bar when turned in said one direction from a rest position and to turn
relatively to the latch bar when turned in said opposite direction from the rest position.
3.	A locking device as claimed in claim 1 or 2, wherein the coupling means
5 (4,17,19) comprises said cam means (6).
4.	A locking device as claimed in claim 3, wherein the locking means
comprises first means (20) turnable with the latch bar (18) and second means
(26) which is engagable with the first means (20) to prohibit turning of the latch
10 bar in response to turning of the coupling means (4,17,19) and, hence, the cam means (6) in said opposite direction relative to the latch bar, and which is disengaged from the first means by turning the coupling means in said one direction.
15 5. A locking device as claimed in claim 4, wherein the second means comprises a slidable locking member (26) controlled by the cam means.
6.	A locking device as claimed in claim 5, wherein the first means comprises
a detent (24), and the slidable locking member (26) is engagable with the detent
20 to prohibit turning of the latch bar.
7.	A locking device as claimed in claim 6, wherein the detent (24) is
disposed on a rotatable locking member (20) adapted to be mounted on the
latch bar (18) so as to turn therewith.
8.	A locking device as claimed in claim 5 or 6, wherein the cam means is
profiled to prevent the slidable locking member (26) from engaging the first
means (24) when the cam means is turned in said one direction whilst permitting
5 the slidable locking member to engage the first means when turned in said opposite direction.
9.	A locking device as claimed in any of claims 5 to 8, wherein the cam
means has a recess (31) which permits the slidable locking member (26) to
10 move into engagement with the first means (24), said recess having a stop portion (32) at one end which prevents the cam means from turning further in said opposite direction upon engagement of the locking member in the recess, and a ramp portion (33) at its opposite end to ease the locking member from the recess when the cam means is turned in said one direction.
10.	A locking device as claimed in any preceding claim, wherein the cam
means (6) and coupling means (4,17,19) are integral with the associated door
handle (3). .	' "	-
\" ¦' '
20 11. A locking device as claimed in claim 10, wherein the associated door handle (3) is rotatably mounted in a housing (2) adapted to be secured in a fixed position relative to the door latch mechanism.
12. A locking device as claimed in claim 11, wherein the locking means
(20,26) is mounted in said housing (2).
13. A locking device as claimed in claim 1, wherein the coupling means comprises a first part (37,40,43) turnable with the cam means and a second part b (36,40,41) turnable with the latch bar and engagable with the first part such that, when the cam means is turned in said opposite direction, the coupling parts are disengaged and, when the cam means is turned in said one direction, the coupling parts are engaged to rotate the latch bar.
10 14. A locking device as claimed in claim 1, wherein the coupling means comprises a passageway (62) of rectangular cross-section, and the latch bar has an external profile which enables the coupling means to turn relative to the latch bar, when turned in said opposite direction, and to turn the latch bar when turned in said one direction.
15. A locking device as claimed in any preceding claim, having indexing means (14) for indexing the coupling means in either of two positions in one of which the locking rmeans (20,25) is actuated, and in the other of which it is released.
V $0*^ 16/^/\ door latch mechanism jcomprising a latch bolt which is retractable in
^response to turning of a latch bar (18) by turning either of two door handles (3) , coupled to opposite ends of the latch bar, and a locking device (1) which is
pvtCftJ^t CJ6&>+*
actuated, so as to prohibit retraction of the latch bolt by turning of one of the
door handles, in response to turning of the other door handle in one direction,
whereafter the locking device is releasable by turning said other door handle in
the opposite direction^gharacterisedln^hat said locking device comprises
5	coupling means (4,17,19) for coupling one end of the latch bar (18) to an
associated door handle (3), said coupling means being coupled to the latch bar so as to turn the latch bar when the coupling means is turned in one direction by the associated door handle and said coupling means being turnable relatively to the latch bar in the opposite direction,
10	locking means (20,26) adapted to be actuated so as to prohibit turning of
the latch bar (18) by said one door handle, and
cam means (6) controlling actuation of the locking means (20,26), said cam means and locking means being able to turn relatively to one another in response to relative turning movement of the coupling means and the latch bar
15 so that relative turning movement of the coupling means in said opposite direction actuates the locking noeans, whereafter the locking means is releasable by relative turning movement of the coupling means in said one direction.
20 17. A latch mechanism as claimed in claim 16, wherein the coupling means comprises a passageway (17) for fitting to the latch bar (18), said passageway having an internal profile (19) which enables the coupling means to engage the latch bar when turned in said one direction from a rest position and to turn
18.	A latch mechanism as claimed in claim 16 or 17, wherein the coupling
5 means (4,17,19) comprises said cam means (6).
19.	A latch mechanism as claimed in claim 18, wherein the locking means
lb 20. A latch mechanism as claimed in claim 19, wherein the second means comprises a slidable locking member (26) controlled by the cam means.
21.	A latch mechanism as claimed in claim 20, wherein the first means
comprises a detent (24), and the slidable locking member (26) is engagable with
2 0 the detent to prohibit turning of the latch bar.
22.	A latch mechanism as claimed in claim 21, wherein the detent (24) is
23.	A latch mechanism as claimed in claim 20 or 21, wherein the cam means
is profiled to prevent the slidable locking member (26) from engaging the first
24.	A latch mechanism as claimed in any of claims 20 to 23, wherein the cam
25.	A latch mechanism as claimed in any of claims 16 to 24, wherein the cam
20 26. A latch mechanism as claimed in claim 16, wherein the coupling means comprises a first part (37,40,43) turnable with the cam means and a second part (36,40,41) turnable with the latch bar and engagable with the first part such that, when the cam means is turned in said opposite direction, the coupling parts are disengaged and, when the cam means is turned in said one direction, the
coupling parts are engaged to rotate the latch bar.
27.	A latch mechanism as claimed in claim 16, wherein the coupling means
comprises a passageway (62) of rectangular cross-section, and the latch bar
5 has an external profile which enables the coupling means to turn relative to the latch bar, when turned in said opposite direction, and to turn the latch bar when turned in said one direction.
28.	A latch mechanism as claimed in any of claims 16 to 27, having indexing
10 means (14) for indexing the coupling means in either of two positions in one of
which the locking means (20,26) is actuated, and in the other of which it'is released.
A locking device (1)for a door latch mechanism having a latch bar (18) turnable to retract a latch bolt of the door latch mechanism by turning either of two door handles (3) coupled to opposite ends of the latch bar is characterised by coupling Imeans (4,17,19) for coupling an associated door
handle (3) to the latch bar for turning; the latch bar when the coupling means is turned in one direction and turnable I relative to the latch bar in the opposite direction,
locking means (20,26) to prohibit turning of the latch bar (18) by one of the door handles (3), and
cam means (6) for controlling actuation of the locking means (20,26), the cam means and locking means being able to turn relatively to one another in response to relative turning movement of the coupling means and latch bar so that the locking means is actuated in response to turning of the other door handle (3) in one direction, whereafter the locking means is releasable by turning the other door handle in the opposite direction.
IN/PCT/2001/01345/KOL
HEELEY PETER
LLETY DAFYDD, MEIFOD, POWYS SY22 6HL, UNITED KINGDOM
1 HEELEY PETER LLETY DAFYDD, POWYS SY22 6HL, UNITED KINGDOM
2 JONES PHILIP DAVID 9 PORTHILL GARDENS, SHREWSBURY, SHROPHSIRE, SY3 9SH, UNITED KINGDOM
E05B 13/08;E05C 1/16
PCT/GB00/01920
1 0006157.2 2000-03-14 U.K.
2 9911593.3 1999-05-19 U.K.