WO2009082246A1

WO2009082246A1 - A smoke alarm

Info

Publication number: WO2009082246A1
Application number: PCT/NZ2008/000346
Authority: WO
Inventors: David Kelly
Original assignee: Schneider Electric (Nz) Limited
Priority date: 2007-12-21
Filing date: 2008-12-22
Publication date: 2009-07-02
Also published as: AU2008261150B2; NZ564722A; AU2008261150A1

Abstract

A smoke alarm comprises a body housing a smoke sensor, a mounting plate for attaching to a surface for mounting the smoke alarm to the surface, a plastics hinge on one side of the body and mounting plate and between the body and mounting plate, and a latch arrangement between the body and mounting plate spaced from the plastics hinge for holding the body normally closed against the mounting plate, the latch being releasable to enable the body of the smoke alarm to be pivoted away from the mounting plate while remaining connected to the mounting plate on one side by the plastics hinge, the plastics hinge on at least one side of the hinge and either the body of the smoke alarm or the mounting plate each comprising interengaging means enabling the body of the smoke alarm to be replaceably detached from the mounting plate. The plastics hinge may be comprised in a component formed separately from either the body or the mounting plate.

Description

"A SMOKE ALARM"

FIELD OF INVENTION

The invention relates to smoke alarms for domestic, commercial, or industrial use of the type which are typically mounted to a ceiling, or high on a wall, or similar.

BACKGROUND

Smoke alarms installed typically comprise a body housing a smoke sensor, and a separate mounting plate for attaching to a ceiling surface for example, for mounting die smoke alarm to die celling. The mounting plate is screwed or otherwise fixed to the ceiling. The body of die smoke alarm houses die smoke sensor and a battery, and is normally attached to the mounting plate but may be detached by hand (without the use of tools), for example to enable replacement of the smoke alarm battery, or if the ceiling is being painted to avoid getting paint on the body of the smoke alarm.

Typically, to fit the body of the smoke alarm to the mounting plate it is necessary to both align die body with die mounting plate while rotating the body, to thereby attach the body to the mounting plate, which it is not always easy to do when reaching overhead, often standing on a chair or ladder for example.

SUMMARY OF INVENTION

The invention provides a smoke alarm comprising a body housing a smoke sensor, a mounting plate for attaching to a surface for mounting the smoke alarm to the surface, a plastics hinge on one side of die body and mounting plate and between the body and mounting plate, and a latch arrangement between die body and mounting plate spaced from the plastics hinge for holding the body normally closed against the mounting plate, die latch being releasable to enable die body of the smoke alarm to be pivoted away from the mounting plate while remaining connected to the mounting plate on one side by the plastics hinge, the plastics hinge on at least one side of the hinge and either die body of die smoke alarm or the mounting plate each comprising interengaging means enabling the body of the smoke alarm to be replaceably detached from the mounting plate.

The body and mounting plate of the smoke alarm of the invention are connected by die plastics hinge in a clam-shell configuration enabling die body of the smoke alarm, after release of die latch typically provided on die odier side of die smoke alarm opposite to die plastics hinge, to be pivoted away from the mounting plate. The body of die smoke alarm may be closed against die mounting plate by pivoting the body of the smoke alarm back towards the mounting plate causing the latch to re-engage, to hold the body of the smoke alarm closed against the mounting plate.

In addition, after the latch has been released and the body of the smoke alarm pivoted away from the mounting plate, the body of the smoke alarm may be separated completely from the mounting plate, to enable the smoke alarm to be taken down completely from a ceiling to which the mounting plate is fixed for example, leaving the mounting plate in place, and may be subsequently reattached to the mounting plate and then pivoted back towards the mounting plate to reinstall the smoke alarm.

In one form a tab is provided on one side of the hinge, shaped to engage into a retaining formation on the rear of the body of the smoke alarm. In an alternative form a tab such a tab may be provided on the other side of the plastics hinge, shaped to engage into a retaining formation on the mounting plate. In a particularly preferred form the plastics hinge is comprised in a component formed separately from either the body or the mounting plate as will be further described. This is advantageous because it enables the mounting plate to be formed of a different plastics material which gives the mounting plate higher stiffness or rigidity, from the plastics hinge component which must be formed from a softer plastics material.

The term "comprising" as used in this specification means "consisting at least in part of. When interpreting each statement in this specification that includes the term "comprising", features ■ other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is further illustrated by the accompanying drawings and following description of a preferred form of the invention, by way of example and without intending to be limiting. In the drawings:

Figure 1 is a view of the preferred form smoke alarm attached to a ceiling surface, with the body of the smoke alarm fixed to the mounting plate,

Figure 2 is a view of the preferred form smoke alarm with the body of the smoke alarm unlatched from the mounting plate and pivoted away from the mounting plate, showing the underside of the mounting plate and the rear of the body of the smoke alarm, Figure 3 is a view of the preferred form smoke alarm with the body latched to the mounting plate, from the rear of the mounting plate,

Figure 4 is a perspective view from of the back of the mounting plate with the body of the smoke alarm fixed to the mounting plate,

Figure 5 is a view of the body and mounting plate of the preferred form smoke alarm with the body unlatched from the mounting plate and illustrating detachment and reattachment of the body to the mounting plate,

Figure 6 is a perspective view from the back and to one side of the mounting plate also with the body removed from the mounting plate showing a separate component comprising the plastics hinge attached to the mounting plate, and

Figure 7 is a close up view showing the interengaging means between the body and mounting plate enabling detachment and reattachment of the body from the mounting plate.

DETAILED DESCRIPTION OF PREFERRED FORM

Referring to the drawings, the body or housing of the smoke alarm is indicated at 1 , and the mounting plate at 2. The body and mounting plate are typically moulded from a plastics material or materials. The body 1 of the smoke alarm may be formed in two parts, which after installation of the smoke sensor including associated circuit board are permanently or semi- permanendy fixed together. A cavity 3 for containing a battery is provided in the rear of die body of the smoke alarm (see Figure 2, and a battery B is shown in position in Figure 5).

Optionally the smoke alarm may be of a type which may be interconnected with other similar alarms, enabling sending of an alarm signal to other alarms located for example in the same house or building but too far away to direcdy detect smoke giving rise to the alarm condition, and in the preferred form an electrical contact 4 from the smoke sensor electronics is exposed through one of apertures 5 in the rear of the body of the smoke alarm, - see Figure 3 — which contacts with a corresponding terminal-6 on the underside of the mounting plate 2 when the body of the smoke alarm is closed against the mounting plate. Referring also to Figure 4, such interconnect and also power wiring in the ceiling or wall of die building may be terminated at the terminals 6 & 7 exposed on the back of the mounting plate. Any excess wiring can be located in the pocket 8 immediately in front of the terminals 8 or in the channel 9, after which at installation of the smoke alarm the mounting plate is subsequently screwed to the ceiling or wall surface on which the alarm is being installed via the mounting holes provided in the mounting plate to of which are indicated at 10. When closed the interconnect contact 4 and the power contacts 11 make contact with their corresponding terminals 6 & 7. The battery of the smoke alarm may act as a back up for operation of the smoke alarm in die event of a power failure. Where the smoke alarm is not permanendy wired into the power supply of the house or building, the battery provides the main power source for the smoke alarm.

A plastics hinge generally indicated at 12 is provided between the mounting plate 2 and main body 1 of the smoke alarm, and a latch arrangement is provided on the opposite side of the smoke alarm. The body 1 and mounting plate 2 are coupled by the" plastics hinge 12 in a clam-shell configuration. Referring particularly to Figure 5, in the preferred form the mounting plate comprises an integral downwardly projecting moulded hook 13, which is engaged by a plastic spring latch provided in the smoke alarm body, when the body 1 of the smoke alarm is closed against the mounting plate 2 (as shown in Figure 1). The latch 14 may be released by pushing on a button or operating tab 15 to unlatch the body 1 from the part hook 13 on the mounting plate 2. The housing body 1 may then be pivoted away from the mounting plate 2, about the plastics hinge 12 on one side. The body 1 may be subsequently pushed closed against the mounting plate 2 to cause re-engagement of the latch 14, holding the body 1 and mounting plate 2 together again until the latch 13 is subsequendy released.

The main body 1 of the smoke alarm can also be detached fully from and subsequendy reattached to the mounting plate 2. This is generally indicated in Figure 5. The plastics hinge 12, on at one side of the hinge, and the body 1 of the smoke alarm, comprise interengaging means enabling the body 1 of the smoke alarm to be replaceably detached from the mounting plate 2. In the preferred form the plastic hinge comprises a tab 16 on one side, having a truncated V-shape as shown, which is shaped to allow easy alignment when slotted between two channel formations 17 provided on the rear of the body 1 of the smoke alarm in a similar V-confϊguration, to couple the body 1 of the smoke alarm to the hinge 12. The tab 16 also comprises extending spring elements 18 on either side, each having a small outwardly facing protrusion 19 at it's outer end, as shown particularly in Figures 6 and 7. The arrangement is such diat, referring to Figure 6 and 7 and also Figures 5 and 2, to release the housing 1 of the smoke alarm completely from the mounting plate 2, the body 1 may simply be pulled downwardly in the direction of arrow A in Figure 5. Doing so will cause the parts 17 to ride over the protrusions (delete) 19 (the spring elements 18 flexing towards each other slighdy), enabling the body 1 to be pulled from the tab 16 and separated from the mounting plate 2. To subsequently reconnect the body 1 to the mounting plate 2, the body 1 is moved upwardly in the direction of arrow B (assuming the mounting plate 2 to be pre-fϊxed to a ceiling for example) so that the tab 16 is entered between the parts 17 on the rear of the body 1 , and is pushed home until the tab 16 and body 1 and particularly parts 17 reach their fully interengaged position shown in Figures 2 and 6. The body 1 may then be pivoted upwardly about the plastics hinge 12 to latch the body 1 closed against the mounting plate 2.

In the preferred form the tab 16 is provided on the body 1 side of the plastics hinge 12, but in an alternative embodiment the tab 16 may be provided on the mounting plate 2 side of die plastics hinge 12. That is, when the housing is detached from the mounting plate 2 the plastics hinge 12 remains affixed to the housing, with the free tab 16 or equivalent on the other side of the plastics hinge. The mounting plate 2 then comprises a retaining formation into which the tab 16 may be engaged, by pushing the body 1 upwardly or sidewardly towards the mounting plate 2, to attach the body 1 to the mounting plate 2 (and reverse for detachment of the body 1 from the mounting plate 2).

Also, in the preferred form shown the plastics hinge 12 is comprised in a component formed separately from either the body 1 or mounting plate 2 of the smoke alarm. This is shown particularly in Figure 6. A component 20 comprising the plastics hinge 12 fits into the back of the mounting plate 2 as shown. In particular a flat part 20a on the other side of the plastics hinge 12 to the tab 16 is received on the back of the mounting plate 2 and is captured between the rear of the mounting plate 2 and the surface to which the mounting plate 2 is fixed when the mounting plate 2 is installed and screwed home to the surface. The hinge component 20 protrudes through an opening in a peripheral rim of the mounting plate 2 as shown. The mounting plate 2 and hinge component 20 may then be formed from different plastics materials. This is advantageous in diat it enables the mounting plate to be formed from a plastics material which will give the mounting plate 2 increased stiffness and rigidity, relative to a softer material from which the plastics hinge component 20 is formed. A stiffer or more rigid mounting plate is advantageous because it minimises distortion of the mounting plate when it is screwed to an uneven ceiling or other surface, which in turn can give rise to ill fitting between the housing 1 and the mounting plate 2 and unreliable operation of the latch 13.

The foregoing describes the invention including a preferred form thereof. Alterations and modifications as will be obvious to those skilled in the art are intended to be incorporated in the scope hereof as defined in the accompanying claims.

Claims

CLAIMS:

1. A smoke alarm comprising: a body housing a smoke sensor, a mounting plate for attaching to a surface for mounting the smoke alarm to the surface, a plastics hinge on one side of the body and mounting plate and between the body and mounting plate, and a latch arrangement between the body and mounting plate spaced from the plastics hinge for holding the body normally closed against the mounting plate, the latch being releasable to enable the body of the smoke alarm to be pivoted away from the mounting plate while remaining connected to the mounting plate on one side by the plastics hinge, the plastics hinge on at least one side of the hinge and either the body of the smoke alarm or the mounting plate each comprising interengaging means enabling the body of the smoke alarm to be replaceably detached from the mounting plate.

2. A smoke alarm according to claim 1 wherein the plastics hinge is comprised in a component formed separately from either the body or the mounting plate.

3. A smoke alarm according to either claim 1 or claim 2 wherein said interengaging means comprises a tab on one side of the plastic hinge and a complementary receiving formation on the rear of the body of the smoke alarm into which the tab may releasably interengage to releasably couple the body of the smoke alarm to the hinge.

4. A smoke alarm according to any claim 3 wherein the tab comprises extending spring elements on either side arranged to snap fit into said receiving formation on the rear of the body of the smoke alarm.

5. A smoke alarm according to any one of claims 2 to 4 wherein the plastics hinge component comprises a flat part on one side of the plastics hinge arranged to be received on the back of the mounting plate and captured between a rear of the mounting plate and a surface to which the mounting plate is fixed, with the hinge component protruding through an opening in a peripheral rim of the mounting plate.

6. A smoke alarm according to any one of claims 1 to 5 wherein the latch is provided on a side of the smoke alarm opposite the plastics hinge.

7. A smoke alarm according to any one of claims 1 to 6 wherein the latch arrangement comprises a hook projecting from the mounting plate which is engaged by a plastic spring latch provided in the smoke alarm body when the body of the smoke alarm is closed against the mounting plate, and which latch arrangement is releasable by pushing on a button or operating tab to one side of the smoke alarm to unlatch the spring latch from the hook on the mounting plate.

8. A smoke alarm according to any one of claims 1 to 7 wherein a cavity for containing a battery is provided in the rear of the body.

9. A smoke alarm according to any one of claims 1 to 8 wherein the body of the smoke alarm on its rear and the mounting plate comprise electrical terminals arranged to interengage and make electrical contact when the body of the smoke alarm is closed against the mounting plate.

10. A smoke alarm according to any one of claims 1 to 9 wherein the mounting plate is formed of a plastics material which gives the mounting plate higher stiffness or rigidity than the- plastics hinge component.

11. A smoke alarm substantially as herein described with reference to the accompanying drawings.