Closure fasteners – Bolts – Sliding
Reexamination Certificate
1999-05-10
2001-03-13
Browne, Lynne H. (Department: 3627)
Closure fasteners
Bolts
Sliding
C292S169140, C292SDIG002, C292SDIG005
Reexamination Certificate
active
06199922
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a latch unit and assembly, and to a method of operating a latch unit. In particular it relates to a latch unit having a slidable bolt, typically for securing a movable panel to a fixed member, such as to a part of a frame for the panel.
In this specification, “left” and “right”, “forward”, “rearward” and similar geometric terms refer to parts in a typical orientation of use as shown in
FIG. 1
, unless otherwise specified.
BACKGROUND TO THE INVENTION
When it is desired to secure a movable panel to a fixed member such as to an upright of an outer frame member, it is known to use a sliding bolt mounted to the panel, the bolt end being fittable behind or within a keeper carried by the frame, whereby to effect the securement. The keeper typically is a plate mounted over a recessed portion of the fixed member or an apertured body secured to the fixed member. The panel typically is a hinged panel which closes perpendicularly or nearly so to the fixed member and thus to the keeper. In use the bolt is slidable between (a) a holding or forwardly extended position in which the bolt end can fit within the recess or aperture provided by the keeper whereby to secure the panel in the closed condition, and (b) a rearwardly retracted or non-holding position in which the bolt end cannot engage the keeper whereby to allow the panel to move relative to the fixed member.
Usually the bolt is mounted in a bolt housing, and is slidable between guides carried by the bolt housing. Various types of bolt and bolt assembly are known, some of which are lockable in the holding position.
One type of bolt assembly has resilient bias means for the bolt, the resilient bias means conveniently being a compression spring or a leaf spring mounted in the bolt housing, the spring urging the bolt end towards the holding position, the bolt end having a chamfer; in the condition of use the chamfer faces the keeper as the panel is being closed. As the panel is moved to its closed condition the keeper forces back the bolt against the spring and into its non-holding position, until the bolt end is aligned with the recess or aperture whereupon the spring urges the bolt into its holding position; this action is often referred to as latching, and the spring as a latch spring, whilst the bolt assemblies of which the biassed and chamfer-ended bolts form a part, are referred to herein as latch units.
One common form of latch unit is designed to be fitted to the interior surface at the rim of an inwardly opening door, such as a front door of a domestic dwelling. For simplicity, the following disclosure will refer to a latch unit for such use (rim latch); however, the latch unit of the invention can also be morticed into a door or other panel, and can be fitted to windows and other movable panels. The keeper for such latch unit will usually be formed with an aperture, sized to receive the bolt end and needing only to be affixed to the door frame or other fixed member in order to provide in the holding position a self-contained embracement of the bolt end, and for simplicity also the following disclosure will assume such a keeper.
A latch unit typically has a bolt which can be moved rearwardly (retracted) by an actuator. The actuator will often be connected at one side to a “thumb-turn” (usually the side which will be to the inside of the building in use), the thumb-turn being rotated to move the bolt from its holding to its non-holding position. At its other side the actuator will often be connected to the barrel of a lock (usually the side which will be to the outside of the building in use), so that from that side it is necessary to insert a key to retract the bolt from its holding position.
Because the bolt of a latch unit would otherwise automatically enter the keeper (“latching” action) when the door is closed, it is common to require a device to be fitted which an occupier can operate in order to permit the force of the latch spring to be over-ridden. Such device will therefore permit the bolt to be retained in its non-holding position i.e. non-latching condition, so that the occupier for instance does not need to use a key or other operating means in order to regain entry into the premises. A means to over-ride the latch spring, and to maintain the bolt away from its holding position is often referred to as a “latch-back” device.
DESCRIPTION OF THE PRIOR ART
It is known to provide a latch-back device for a rim latch, the device typically comprising a slidable plate which can be moved substantially perpendicularly to the direction of movement of an extension secured to a short latch bolt. Whilst the latch bolt is being held in its non-holding position, as by a thumb-turn, the plate can be moved into engagement with a recess or the like in the extension for the latch bolt so that thereafter the plate retains the extension and thus the latch bolt in its non-holding position. When the occupier or other person desires to re-activate the latch unit, the plate is moved to release the extension whereby to permit the latch bolt to move axially, specifically to be urged to its holding position by the latch spring.
It is possible to operate this known latch-back device with one hand, but this is difficult and often awkward to achieve, so that in practice setting the latch-back device often requires the simultaneous use of both hands, one hand to rotate and hold the thumb-turn and the other then to move the plate. In addition, the operating means for the plate is small, and can be difficult to grip so that the latch-back device may be seldom or never used by the elderly or disabled. It is believed that these known (two-handed) latch-back devices are particularly difficult to operate for those suffering from arthritis or rheumatism. The known latch back devices are not safe to use on the safety exit (“panic”) doors of multi-occupier premises.
STATEMENT OF THE INVENTION
We seek to provide a latch unit having a retaining means or latch-back device which reduces or avoids the disadvantages with the known devices, and which can be simpler to operate. In particular, we seek to provide a latch unit in which the latch-back device can automatically re-set, and which can thereafter be released by one hand. We therefore seek to provide a latch unit in which the latch-back device does not require a latch-back plate or the like to be moved by the user whilst the bolt is simultaneously being held manually in a retracted position against the force of the latch spring.
According to one feature of the invention we provide a method of operating a latch unit, the latch unit having a bolt, the bolt being movable in a first direction between a holding position in which a part of the bolt projects from the housing and a non-holding position in which the said part projects less from the housing, the bolt being biassed towards the holding position, the latch unit having actuating means for moving the bolt in said first direction from its holding position to its non-holding position against said bias, the bolt having a retaining means to retain it at a position away from its holding position, characterised in that the retaining means can be activated to retain the bolt only upon further movement of the bolt in the said first direction to a position rearwards of the non-holding position.
The retaining means is automatically activated upon said further movement of the bolt in the said first direction. The retaining means is conveniently a pivoted lever, or alternatively a slidable plate or lever.
Preferably, in the non-holding position the said part does not project from the housing, perhaps being flush with a planar outer forward surface of the housing.
It is thus a feature of this invention that the bolt may be moved by the actuating means in the first direction from its holding position to its non-holding position and that only upon further or continued movement in said first direction effected by the actuating means can the retaining means be effective. In particular, we provide a method of operating a latch
Barrett William A.
Browne Lynne H.
Fuierer Marianne
Hultquist Steven J.
Walsh John B.
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