AU687503B2 - Door latch - Google Patents

Description

P/00/011 28/"9 AUSTRALIA Regulation 3.2 Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD

PATENT

Invention Title: DOOR LATCH *.Tie following statement is a full description of this invention, including the best *4ii~thod of performing it known to me:- S e (Se w it hin) THIS INVENTION relates to a door latch and is more specifically concerned with a doorlatching mechanism which holds a door closed until it is required to open it.

Most households with infants fit latches on cupboards and cabinets to prevent the infants from opening them and then playing with their contents. Usually conventional turnbuckle latches are used for this purpose but they are unsightly and also require a hole to be drilled on a visible part of the cabinet frame to receive the fixing screw for the turnbuckle. Other forms of mechanical latch are also available but a child quickly learns how to operate these by studying the actions of its parents when opening the cupboard.

An object of this invention is to provide an improved latching mechanism for holding a door of a cabinet closed.

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In accordance with the present invention, a door latching mechanism includes a unit for fitting into a surround of a door apertureat a position at which a ferro-magnetic latching member in the unit is gravity-biased towards a door-latching position, and a hand-held, magnetic actuator separate from the unit, for displacing the member to a door-freed S: position magnetically when placed at a pre-determined location on the surround; the unit being formed as a plastics tube spanned in an intermediate portion by an apertured web and containing the latching member which is formed as a tappet having its stem extending

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through the web aperture and its head larger than the aperture and located on one side thereof, the axial length of the head being substantially less than the axial length of the portion of the tube in which it moves when the mechanism is operated, so that at all operating positions of the mechanism the head remains within the confines of the tube.

By placing the actuator on a work-top surface immediately above the unit, the tappet head is attracted upwards and frees the stem from the opening in the door may then be opened. The hand-held actuator may be provided with a felted under-surface so that it does not scratch the work-top surface with repeated use.

In an alternative arrangement, the member is hinged to the unit and is gravity biased to turn about the hinge towards its door-latching position. The member may be turned in the other direction about the hinge by the magnetic attraction of the actuator when it is required to free the door for opening.

The advantage of the invention is that the hand-held actuator can be placed on a shelf above adult-head height, so that a child cannot reach it. Without the actuator, the door cannot be opened. It will be noted that the latching of the door in the closed position is effected without the attachment of unsightly devices to its exposed surfaces, and without blemishes to the exposed surfaces of the door and its surround.

The invention will now be described in more detail, by way of example, with reference to the accompanying diagrammatic and informal drawings, in which:

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.•FIGURE 1 is a vertical section through one upper corner portion of a hinged door of a kitchen cabinet held closed by a door-latching mechanism; and,

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2 is an exploded view showing component parts of the door-latching mechanism of figure 1.

Figure 1 sh, door 1 of a cabinet which is hinged to close 3 rectangular vertical aperture 2 benealu a work-top 3.

The closing upright marginal edge of the door 1 is provided in its upper edge, adjacent its upper corner, with an opening 4 in which is held a cup socket The upper side of the surround of tne door 1, is provided by a front edge 7 of the underside of a work-top. An upright hole 9 is drilled into the underside of the work-top at a concealed position lying directly above the opening 4. An open-ended tubit ar plastics unit 11 is fitted into the hcle 9 and cemented in position.

Figure 2 shows the unit 11 in more detail. It comprises an upright cylinder formed internally with a web 13 which spans horizontally across its intermediate portion and has a central aperture 17. The vertical space above the web 13 is greater than the depth

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of the cup socket 5. A ferromagnetic tappet 14 has a circular head 15 which is located above the web 13, as shown in figure 1, and a vertical central stem 16 which extends down through the web aperture 17 and protrudes atits underside beyond the undersurface of thle work-top 3 to provide a member for holding the door closed, as shown in figure 1.

A hand-held actuator 18 comprises a plastics block of material covered at its underside by a layer of felt 19 and having a magnet 20 embedded in it. The horizontal dimension of the magnet is substantially larger than the head of the tappet so that, by positioning the actuator block on the work-top 3 above the general position of the unit, the tappet 14 is attracted upwardly and the lower end of its stem 16 lifts out of the cup-socket 5. The door may then be opened.

The above described mechanism is cheap to manufacture and easy to install. It is reliable in operation and cannot be operated without the actuator 18. Thus, by keeping the actuator 18 at a remote location, where small children cannot reach it, unauthorised access to the cupboard is prevented.

Although the invention has been described with reference to a mechanism for fitting above the door, it is within the scope of the invention to have a unit which is fitted in the upright closing jamb forming part of the surround of the door. In this case, the sliding o tappet may be replaced by a horizontally-hinged segment having a latching member which fits into an edge opening in the door when the door is closed. The segment is gravity biased to urge the latching member towards its door-latched position. The segment also carries a magnet or armature which turns it towards a door freed position when the actuator is placed in a predetermined position on the door surround. The door may then be opened.

The ubstitution of a hinged latching member for a gravity-operated sliding one, is less attractive commercially as it is more expensive to manufacture and harder to fit.

In some situations it may be desirable to allow the door to be slammed shut, without obstruction from the latching member, when the actulator is not present on the work-top 3. This result may be achieved by providing the lower end of the stem 16 with a rounded under-surface and positioning a shallow ramp surface on the opening side of the cupsocket 5. During terminal movement of the door to its closed position, the underside of the stem 16 rides up the ramp surface and lodges in the socket when the door is in its fully closed position.

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In a further example of the invention, also not illustrated, the latching member comprises a horizontally displaceable, ferromagnetic, slide bolt mounted for axial movement along a plastics smooth-walled tube let into the door surround, and having its axis horizontal. The actuator is provided with a magnet which, by 'wiping' the actuator horizontally in the required direction of movement of the bolt and along the exposed surface of the surround next to the magnet, displaces the bold magnetically in the required direction to engage, or disengage the latching mechanism, as required.

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Claims (4)

1. A door-latching mechanism which includes a unit for fitting into a surround of a door aperture at a position at which a ferro-magnetic latching member in the unit is gravity-biased towards a door-latching position, and a hand-held, magnetic actuator separate from the unit, for displacing the member to a door-freed position magnetically when placed at a pre-determined location on the surround; the unit being formed as a plastics tube spanned in an intermediate portion by an apertured web and containing the latchirg member which is formed as a tappet having its stem extending through the web aperture and its head larger than the aperture and located on one side thereof, the axial length of the head being substantially less than the axial length of the portion of the tube in which it moves when the mechanism is operated, so that at all operating positions of the 0* mechanism the head remains within the confines of the tube. *t4,

2. A mechanism as claimed in claim 1, arranged and adapted to operate substantially as hereinbefore described.

3. A mechanism as claimed in claim 1, arranged and adapted to operate substantially as described with reference to the accompanying drawings.

4. A door hinged to close an opening in a surround and arranged to be held in its closed position by a mechanism as claimed in any one of the preceding claims. Dated: this <4?day of November, 1997. TRICIA O'KEEFE and PETER JOHN O'KEEFE By (Applicant's Patent A.orney) (Applicant's Patent orney) ABSTRACT (Figure 1 refers) A door located beneath an work-surface is held closed by a shank (16) of a ferro-magnetic stud (14) having a head (15) lying above an apertured web (13) spanning across the interior of a plastics tube unit (11) with the shank (14) extending down through the web aperture. To free the door for opening, a hand-held magnetic actuator (18) is placed on top of the work- surface This magnetically attracts the stud (14) upwardly so that its shank (16) is raised out of a socket piece let into the upper edge of the door *o oe* 6 *oo III~" II