Note: Descriptions are shown in the official language in which they were submitted.
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1 "LATCH MECHANISMS"
2 This invention relates generally to latch mechanisms
3 and improvements therein.
4 The latch mechanism of the present invention may be
adapted to be mounted in an assembled position to a door or
6 other closure. To this end, as is conventional, the door
7 may include a first bore therein extending between opposite
8 major side walls thereof and a second bore extending from a
9 side edge of the door to the first bore. A striker plate
may be provided on a section of a door frame surrounding the
11 door the striker plate being adjacent the second bore.
12 Currently known latch mechanisms are relatively
13 complicated mechanisms which are expensive to manufacture
14 and difficult to maintain. Furthermore, the various
components have almost always been formed from metal.
16 It is an object of the present invention to provide an
17 improved latch mechanism and parts for use therein which is
18 relatively uncomplicated and is suited for manufacture from
19 substantially all plastics material.
According to one aspect of the present invention there
21 is provided a latch bolt assembly for use in a latch
22 mechanism the latch mechanism including an actuator for
23 operating the latch bolt assembly; the latch bolt assembly
24 comprising; a casing having a guide passage therein with
openings at each end of the guide passage and a central axis
26 extending between the openings, a bolt device including a
27 head section with a tongue and a control section, at least
28 part of the bolt device being receivable within the guide
29 passage for movement therein in the direction of the central
axis between a latched position and a retracted position.
31 The control section is operatively connectible to the
32 actuator of the latch mechanism so that operation of the
33 actuator causes movement of the bolt device in the guide
34 passage. The assembly further includes biasing means
disposed between co-operating stops on the casing and on the
36 bolt device such that in an operating position the biasing
37 means normally urges the bolt device towards the latched
38 position.
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1 In the assembled position, the casing of the latch bolt
2 assembly is fitted to the door so that at least part thereof
3 is disposed within the second bore with the recess being
4 generally axially aligned with the axis of the second bore.
The bolt device is movable relative thereto in the recess so
6 that in the latched position the tongue is capable of being
7 located adjacent the striker plate so as to inhibit opening
8 of the door. In the retracted position, the tongue is clear
9 of the striker plate so that the door can be opened. The
actuator is at least partially disposed within the first
11 bore and operatively connected to the bolt device so as to
12 cause movement thereof.
13 Preferably the casing and the bolt device include co-
14 operating regions which together form a housing which
retains the biasing means captive in the operating position.
16 The co-operating regions preferably include a recess
17 disposed in one of or both the casing and the bolt device so
18 as to define the housing for the biasing means. In one
19 preferred form, a recess is provided in the bolt device the
other part of the housing being defined by an internal wall
21 surface of the guide passage. Preferably, the stop on the
22 casing comprise a flange projecting into the recess in the
23 bolt device the stop on the bolt device being defined by an
24 end wall of the recess therein.
The head section of the bolt device may be generally
26 complementary in cross-sectional shape to that of the guide
27 passage.
28 The bolt device may comprise an elongated body with the
29 head section at one end and the control section at the other
end. Preferably the body intermediate its ends is waisted
31 or reduced in cross-sectional dimension. This has the
32 effect of providing a self-aligning feature which may be
33 required due to installation error.
34 The biasing means may be in the form of a compression
spring means such as a helical compression spring.
36 An access aperture may be provided in the wall of the
37 bolt device opposite to the recess and extending into the
38 recess which facilitates mounting of the biasing means in
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1 the operating position. The axis of this aperture is
2 preferably inclined toward one end of the recess so that
3 when the bolt device is disposed within the guide passage
4 the biasing means can be passed through the aperture and
correctly positioned within the housing in the operating
6 position.
7 The actuator of the latch mechanism may be in the form
8 of a rotatable shaft operatively connected to the control
9 section of the bolt device so that rotation of the actuator
shaft causes movement of the bolt device between the latched
11 and retracted position. As mentioned above, the actuator
12 when in the assembled position is at least partially
13 disposed within the first bore for rotation therein. The
14 actuator shaft may be operatively connected to one or more
operating handles by which the actuator can be rotated.
16 Preferably the control section of the bolt device
17 comprises at least one cam reaction surface which is
18 engageable by a co-operating cam member on the actuator.
19 The cam member and cam surface are preferably configured so
that the cam member rolls along the cam reaction surface.
21 Preferably two cam members are provided on the actuator
22 shaft each being associated with a respective reaction
23 surface the arrangement being such that rotation of the
24 actuator shaft in either direction causes movement of the
bolt device from the latch to the retracted position and the
26 biasing means tends to return the bolt device to the latched
27 position.
28 In one preferred form, the control section comprises an
29 aperture in an end portion of the bolt device remote from
the head section the aperture having an end wall the inner
31 surface of which defines the cam reaction surfaces.
32 Preferably the end wall includes a notch therein for
33 receiving a complementary rib on the actuator shaft with the
34 cam members being disposed on opposite sides of the rib.
Preferably the biasing means urges the cam member and
36 associated reaction surface into engagement with one
37 another.
38 In one form of the invention, the casing may comprise a
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1 tubular section having the guide passage therein and a
2 mounting plate at one end of the tubular section which is
3 adapted to be secured to the side edge of the door with the
4 tubular section projecting into the second bore. The bolt
device is disposed within the passage with its control
6 section extending into the first bore and the actuator shaft
7 extends axially of the first bore between the two opposed
8 sides of the door.
9 The latch mechanism may further include a support
housing to which the operating handles may be mounted. The
11 support housing may include a tubular section which extends
12 through the first bore in the door and a flange which is
13 adapted to be secured to the door so as to hold the support
14 in place. Preferably a portion of the internal wall surface
of the tubular section forms a bearing surface for the
16 handles which preferably are in the form of rotatable knobs.
17 The actuator shaft is adapted to extend through the tubular
18 section of the support and is operatively connected at each
19 end to a respective handle. An aperture may be provided in
the wall of the tubular section of the support provides for
21 operative connection between the latch bolt assembly and the
22 actuator.
23 Preferably all of the parts referred to above with the
24 exception of the biasing means are formed from a suitable
plastics material although it will be appreciated that other
26 materials could be used.
27 According to another aspect of the present invention
28 there is provided a locking device for a latch mechanism,
29 the latch mechanism including a bolt device movable between
the latched and retracted positions, an actuator shaft
31 operatively connected to the bolt device such that rotation
32 thereof about an axis of rotation causes movement of the
33 bolt device between the latched and retracted position and
34 at least one operating handle operatively connected to the
actuator shaft by which the actuator shaft can be rotated.
36 The bolt device may be in the form of the latch bolt
37 assembly described above although it could take other forms.
38 Basically, the locking device of the invention comprises a
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1 locking element which is mounted for movement in the
2 direction of the axis of the actuator shaft between a lock
3 position in which rotation of the actuator shaft by the
4 handle is inhibited and a release position in which the
actuator shaft can be rotated by the or each operating
6 handle. The locking device further includes a control
7 member operatively connected to or engageable with the
8 locking element, the control member being mounted for
9 movement in the direction of the axis of the actuator shaft
between the first and second positions whereby in said first
11 position the locking element is caused to adopt the lock
12 position and in the second position the locking element can
13 adopt the release position. The arrangement is such that
14 when in the first position, the control member is capable of
rotational movement and in the second position it is
16 inhibited from such rotational movement. The locking device
17 further includes an actuating member operable to cause the
18 axial movement of the control member and drive means
19 associated with the actuating member and the control member
for causing rotation of the control member when in the first
21 position.
22 Preferably the locking device further includes a
23 mounting body operatively connected to the actuator shaft
24 the mounting body being adapted to support at least part of
the locking element and the control member and permit axial
26 movement therealong in the direction of the axis of the
27 actuator shaft. The mounting body preferably operatively
28 connects the actuator shaft to the handle and may comprise a
29 tubular or rod like member operatively connected to one end
of the actuator shaft.
31 In one form, the locking element may comprise a first
32 part which includes one or more segments which, in the lock
33 position, are adapted to engage a stop which may be formed
34 on the door or on the support housing of the latch mechanism
described earlier to inhibit rotation of the actuator shaft
36 the first part further including a pair of arms which are
37 operatively connected to a second part which comprises a
38 ring-like element slidable along the mounting body.
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1 The control member may be in the form of an annular
2 disc-like element receivable on the mounting body for
3 movement therealong in the axial direction. The disc element
4 is adapted to engage the ring-like element of the locking
element so that axial movement thereof causes movement of
6 the locking element between the release position to the
7 locking position
8 Preferably the drive means comprises a plurality of
9 ratchet elements on the disc-like member engageable by
projections on the actuator. The actuator preferably
11 comprises a manually depressible button and is arranged such
12 that by depressing the button the projections engage the
13 ratchet elements so that when the locking member is in the
14 lock position the control member is capable of being
rotated. Means is provided for inhibiting the rotation of
16 the control member by the drive means when the locking
17 element is in the release position. Such means may be in
18 the form of one or more axially extending ribs which are
19 adapted to co-operate with apertures in the control member
thereby preventing relative rotation between the two parts.
21 Biasing means may be provided for urging the locking
22 element into the release position. The biasing means may be
23 in the form of a helical spring adapted to act on the second
24 part of the locking element.
The operation of the preferred form of the locking
26 device is as follows. When the actuator button is depressed
27 it causes the disc-like control member to move axially along
28 the mounting body thereby moving the locking element into
29 the lock position. In this initial movement the control
member is inhibited from rotation because of the ribs on the
31 mounting body.
32 When the control member clears the ribs the ratchet
33 element and projections co-operate to cause a limited
34 rotation of the control member so that the apertures are
offset from the ribs and as such the control member is
36 prevented from returning under the influence of the biasing
37 spring. In this position, the locking element is in the
38 lock position and rotation of the actuator shaft is
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1 inhibited.
2 Further depression of the button causes the projections
3 and ratchets to co-operate to cause a further partial
4 rotation so that the apertures and ribs are aligned thereby
enabling the control member and the locking element to be
6 axially moved into the release position.
7 Preferred embodiments of the invention will be
8 hereinafter described with reference to the accompanying
9 drawings and in those drawings:-
Figure 1 is an exploded isometric view showing one form11 of latch mechanism according to the invention;
12 Figure 2 is a sectional side elevation showing the
13 latch bolt assembly according to the present invention;and
14 Figure 3 is an exploded isometric view showing the
latch mechanism including the locking device according to
16 the present invention.
17 Referring to the drawings, the latch mechanism
18 generally indicated at 1 is adapted to be mounted to a door
19 4 having a first bore 5 therein and a second bore 10 which
extends through to the first bore 5. A striker plate 1 is
21 provided as is conventional.
22 The latch mechanism 1 includes a latch bolt assembly
23 comprising a casing 9 comprising a tubular section 9A having
24 a guide passage 9B therein and a face plate 9C by which the
casing is secured to the side edge of the door by means of
26 screws 11 the tubular section 9A extending into a second
27 bore 10 in the door 4. The latch bolt assembly further
28 includes a bolt device 12 having a head section 12A and a
29 control section 12B, the body portion between the head
section and control section being waisted at 12F.
31 Biasing means in the form of a compression spring 16 is
32 disposed within a recess 12C in the bolt device 12 the
33 compression spring 16 extending between stops 9D and 12D.
34 The spring 16 can be mounted within the recess 12C via
access aperture 12G.
36 The control section 12B of bolt device 12 includes a
37 pair of cam reaction surfaces or pads 12E having a locating
38 slot 12F therebetween. The control section 12B of the bolt
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1 device 12 is disposed within the first bore 5.
2 An actuator in the form of an actuator shaft 13 extends
3 through the first bore 5 and is operatively connected to
4 operator handles in the form of knobs 7 and 8 by means of
wing nuts 14 and 15. The actuator shaft 13 includes cam
6 sections 13A which engage against pads 12E. A centering rib
7 13B is disposed within slot 12F.
8 The compression spring 16 operates between the stops 9D
9 and 12D on the casing and bolt device exerting a force on
the bolt device such that continuous contact is achieved
11 between the bolt device and the cams of the actuator shaft
12 13 so that engagement of the bolt device to the striker
13 plate is assured.
14 The cams of the actuator shaft 13 are symmetrical but
offset to the shaft/center line axis. The cams of the shaft
16 bear on the inner pads of the bolt device in such a way that
17 rotation of the cam shaft in either direction causes either
18 the upper or lower cam to retract the bolt device.
19 To open the door clockwise or anti-clockwise, rotation
is applied to either knob 7 or 8 thus causing the bolt
21 device to be retracted by rotation action of the shaft 13
22 and is guided in the linear direction by the casing 9
23 thereby disengaging from the striker plate 1.
24 Upon releasing door knob 7 or 8 and closing the door,
compression spring 16 provides the necessary tension to
26 return the system to its original position automatically
27 with the tongue of the bolt device re-engaging the striker
28 plates and both cams of the shaft being returned to full
29 contact with the inner pads of the bolt assembly.
Fascias 17 and 18 serve to cover the nut attachment of
31 knobs 7 and 8 and to present a smooth appearance when fitted
32 to the knobs. Fascias 17 and 18 are retained to knobs 7 and
33 8 by means of a series of tongues which are moulded integral
34 with the fascias and which register in and snap into
matching openings in knobs 7 and 8 so as to be firmly
36 retained.
37 Escutcheons 19 and 20 are provided for decorative
38 purposes only and are arranged as a snap-on fitting to
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1 support 2 and flange 3.
2 A support housing 2 is mounted within the first bore 5
3 and held in position by means of flange 3 and a flange on
4 the support housing 2. The support housing 2 provides a
5 bearing surface for the operating knobs 7 and 8.
6 The locking device which comprises a separate aspect of
7 the present invention is shown in more detail in Figure 3.
8 The locking device includes a locking element 24 which is
9 mounted for movement in the axial direction of the axis of
the actuator shaft between a locked position in which
11 rotation of the actuation shaft by the operator handles is
12 inhibited in a release position in which the actuator shaft
13 can be rotated. The locking element 24 includes a first
14 part 24A in the form of a yoke having at one end two
15 segments 24B. The segments can act between the shaft 3 and
16 the support housing 2 to prevent rotation of the shaft. At
17 the opposite end of the first part 24A there are two arms or
18 probes 24C which are a free sliding fit in matching openings
19 in the knob and extend through so as to be secured to a
20 second part 23 which is in the form of a ferrule or ring-
21 like element which is slidably mounted on a mounting body
22 22.
23 The mounting body 22 iS in the form of a tubular member
24 which is used to secure the cam shaft to the operating knob.
25 The body 22 has a series of ribs 22A at one end thereof for
26 reasons which will become apparent.
27 The support housing 2 possesses a raised rib (not
28 shown) within its internal diameter, this rib being
29 positioned such that contact by one or both of the segments
30 24B of yoke 24A prevent rotation of yoke 24A and also
31 prevent rotation of the shaft 3 rendering the mechanism
32 locked.
33 Spring 26 provides the force necessary to hold yoke 24A
34 out of contact with support housing 2 for normal operation
35 of the latch mechanism; ie the locking element is in the
36 release position.
37 Ferrule 23 and yoke 24A act as one unit ie the locking
38 element which can be made to slide into engagement or
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1 disengagement with the rib within the support housing 2 to
2 lock or unlock the latch mechanism. The control member
3 comprises an annular disc-like member 27 receivable on the
4 tubular mounting body 22 for movement thereon. Drive means
in the form of a ratchet 27A is provided on disc 27. The
6 disc 27 has a circular but notched opening at its middle
7 which matches the ribs 22A at the end of the tubular member
8 22. Ratchet 27 is allowed to slide freely on the tubular nut
9 23 but rotation is prevented by the longitudinal ribs 22A
thereon.
11 Actuator button 28 is cylindrical in form whose inner
12 opening matches the ribbed end of the tubular nut 22 is in
13 free sliding fit on the nut. Rotation of the button 28 is
14 prevented by the longitudinal ribs.
The device means further comprises a set of teeth 28A
16 on button 28. In the normal unlocked condition, continuous
17 contact exists between the teeth and ratchet and the teeth
18 on the button 28.
19 When button 28 is depressed and made to move along the
tubular nut 22 control member 27 is also forced to move and
21 carry before it ferrule 23 which in turn causes yoke 24A to
22 engage with the rib within the support housing 2 and lock
23 the latch mechanism.
24 The ratchet on the control member and the teeth 28A on
the button 28 are so arranged that when button 28 is
26 depressed and control member 27 is caused to slide and pass
27 the end of the ribs 22A and thereby partial rotation of the
28 control member 27 takes place as a result of the
29 interengagement of ratchet elements 27A and teeth 28A. The
control member 27 is thereby retained in this position by
31 the longitudinal ribs 22A of the tubular nut 22 thus
32 ensuring that the yoke is retained in the locked position.
33 Spring 29 is provided to return button 28 to its
34 original position.
To unlock the system, the button is again depressed
36 causing tooth contact with ratchet 27A. The tooth form again
37 causes partial rotation of control member 27 allowing the
38 holes in control member 27 to once more align with the
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1 longitudinal ribs of tubular nut 22 and become free to
2 slide. Spring 26 then provides the force necessary to
3 disengage yoke 24 from the rib within the support 2 and
4 return yoke 24, ferrule 23 and control member 27 to the
original unlocked position.
6 Fascia 21 is similar to previously described fascia 17,
7 except that an opening is provided for access to button 28.
8 The shape of button 28 is such that it will not pass through
9 the opening in fascia 21.
Finally it is to be understood that various
11 alterations, modifications and/or additions may be
12 incorporated into the various constructions and arrangements
13 of parts without departing from the spirit and ambit of the
14 invention.
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