The present invention 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 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 doors, gates and the like in closed positions and, typically, comprise a spring loaded latch bolt which is resiliently urged outwardly of the 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 mechanism is to be locked in its latched position, the latch normally incorporates a separate 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 turnable member.
U.S. Pat. No. 1,688,240 comprises a spring loaded latch bolt which is resiliently urged 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 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 first 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 bolt to extend beyond the door, whereupon the latch bolt pulls the locking member from the slot, thus releasing the outside door knob.
U.S. Pat. No. 5,433,495 also discloses a door latch mechanism within a body of a door, comprising a latch bolt which is retractable in response to turning of a door knob on either side of the door. One of the knobs is designed to be 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.
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.
According to one aspect of the present invention there is provided a 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 latch 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 turning of the cam means in response to turning of said one door handle in the opposite direction.
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 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 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 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.
It may be desirable for the cam means to be profiled to prevent the slidable 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 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.
The locking device may include a door handle with the cam means integral with the handle. Conveniently, the handle is rotatably 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 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 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 turn.
According to this aspect of the present invention there is provided an auxiliary locking device, which may be fitted to an existing latch. In this 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 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 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 response to turning of said one door handle in one direction, and the locking means is releasable by turning of the cam means in response to turning of said one door handle in the opposite direction.
In one embodiment, the cam means of the latch mechanism 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 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 of movement relative to the latch bar, when turned in said one 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 latch bars is rotatable in said one direction to cause its actuating member to engage the latch bolt and prohibit retraction thereof by turning of the other latch bar.
Embodiments of the present Invention will now be described, by way of example, with reference to the accompanying drawings, in which:
The locking device 1 illustrated In
Referring to
The handle body 4 has a blind passageway 17 extending into the body from the inner end thereof opposite the lever arm 5 and fitting onto the adjacent projecting end of the latch bar 18 (shown in chain dotted lines on FIG. 5). The passageway 17 has an internal profile formed from specially designed longitudinally extending ribs 19 which are arranged so as to enable the handle to engage and turn the square section latch bar, when the handle is turned in a clockwise direction from the rest position, and enable the handle to turn relatively to the latch bar when the handle is turned in an anti-clockwise direction from the rest position.
Disposed in the housing 2, adjacent the inner end of the part 6 of the handle body 4, is an annular cam or locking bush or member 20. (see also
Cast on the inside of the housing 2, adjacent its periphery, is a locking bar guide 25 (see
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 of the housing and in the base plate 22 for these screws.
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 1.5 mm.
When the handle 3 of the locking device 1 is in its rest position shown in
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 18 so that the latter turns with the handle and, hence, the latch bolt is retracted 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 20 to return to the rest position where the detent 14 re-enters the pocket 12 to index,the handle in this rest position.
To lock the door, the handle 3 is lifted upwardly from its rest position, in an anti-clockwise direction. In this direction of rotation, because of the design of the ribs 19, the handle turns 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 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 anti-clockwise movement of the handle is positively prevented by the cam follower engaging the stop side 32 of the cam recess 31. The latch bolt is, thus, firmly locked against turning, preventing operation of the latch from the opposite side of the door. The door is thus locked. 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.
In a modification shown in
In another modification shown in
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 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 block to move into locking relation with the latch bar under control of the cam member.
In yet another modification shown in
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 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.
Moreover, the operation of the locking device is simple. With the door 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 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
In a modification shown in
Hence, if either handle is turned, for example, through 45°, in this 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
Whilst particular embodiments have been described it will be 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 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.
Number | Date | Country | Kind |
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9911593 | May 1999 | GB | national |
0006157 | Mar 2000 | GB | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCTGB00/01920 | 5/19/2000 | WO | 00 | 11/16/2001 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO0071841 | 11/30/2000 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
1688240 | Keigwin | Oct 1928 | A |
4720127 | Doolan | Jan 1988 | A |
4900073 | Doolan | Feb 1990 | A |
4920773 | Surko, Jr. | May 1990 | A |
5077994 | Trull et al. | Jan 1992 | A |
5433495 | Uffner | Jul 1995 | A |
5651280 | Park | Jul 1997 | A |
Number | Date | Country |
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3840183 | May 1990 | DE |