AU658528B2

AU658528B2 - An improved hollow wall mounting device

Info

Publication number: AU658528B2
Application number: AU46058/93A
Authority: AU
Inventors: Simon David Hill
Original assignee: Gerard Industries Pty Ltd
Current assignee: Clipsal Australia Pty Ltd
Priority date: 1992-09-04
Filing date: 1993-09-02
Publication date: 1995-04-13
Anticipated expiration: 2013-09-02
Also published as: AU4605893A

Description

658528

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Regulation 3.2 4 i Name of Applicant: GERARD INDUSTRIES PTY LTD Actual Inventor: SIMON DAVID HILL .6 Address for Service: R K MADDERN ASSOCIATES, 345 King William Street, Adelaide, South Australia, Australia Invention title: "AN IMPROVED HOLLOW WALL MOUNTING DEVICE" Details of Associated Provisional Application No: PL 4479 filed 4th September 1992 The following statement is a full description of this invention, including the best method of performing it known to us.

This invention relates to an improved mounting device for releasably mounting an object within an opening in a hollow wall or ceiling. In particular, the invention is directed to an improved mounting device for mounting an electrical fitting, such as a power outlet or switch, to a hollow wall, wherein the fitting comprises a facia plate which is arranged to lie flat against the wall, and a body portion which projects inwardly through an opening in the wall.

It is well known to mount electrical fittings, such as switches and power outlets, to walls using wall boxes or mounting brackets which are placed behind the wall durirg construction, and fastening screws which secure the fitting to a facia plate which in turn is secured by further mounting screws to the wall boxes or bracketry.

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The applicant is also aware of an exhaust fan mounting which makes use of a plurality of rotatable clamping arms located around the periphery of the main frame of the fan and which are movable between retracted and extended positions. The S. S arms, when in their extended positions clampingly engage against marginal edge portions of the opening in which the fan is installed, Each clamping arm is caused to rotate by means of a screw which extends through a tubular boss portion integrally formed at the inner end of the clamping arm, the arrangement being such that as the screw is t.ghtened, the clamping arm rotates to its extended clamping position, rotation of each arm being limited by a stop which is integrally moulded on the main frame.

It is the main object of the present invention to provide a hollow wall mounting device which eliminates the need for wall boxes and mounting brackets normally used with prior art mounting arrangements, and which will allow objects such as wall mounted electrical fittings, to be easily and quickly mounted in position.

It is a further object of the present invention to provide an improved hollow wall mounting device which is simple and 2 inexpensive to manufacture, and which can be used to mount a wide variety of items within a hole or aperture in a hollow wall or ceiling.

In its broadest form therefore, the present invention provides an improved hollow wall mounting device for releasably mounting an object in an opening in a wall, comprising a pair of co-operable interengaging arms rotatable relative to one another about an axis, one of said arms constituting a swingable clamping arm, the other a locking arm, each said arm having a screw receiving hollow mounting stem at its inner end, each said stem having a bore extending therethrough co-axial with said axis, said stems slidably

S.

engaging one within the other, a fastening screw receivable within and extending through said bores, limit means for limiting the extent of rotational movement of said clamping arm relative to said locking arm so that the clamping arm is constrained to swing between a retracted position wherein it lies to the same side of said axis as the locking arm and an extended position where it projects to the side opposite to SS 55 that of said locking arm, arranged and constructed so that upon initial tightening of the screw, the clamping arm is rotated to its extended position wherein it is locked, by o said limit means, against further rotational movement in the tightening direction of the screw, whilst further tightening of the screw causes the swing arm to clampingly engage :against an inner marginal edge portion of the opening in the wall in which the fitting is installed, with said locking arm being arranged to bear against a fixed surface for restraining same against rotation.

Preferably, the mounting stem of the clamping arm is sized so as to slidably snugly receive the mounting stem of the locking arm.

Preferably, the limit means for limiting relative rotation between the pair of interengaging arms comprises an internal key extending axially along the bore of the stem of the clamping arm and a semicircular keyway on the outer surface 3 of the stem of the locking arm. The key and keyway cooperate together to limit the extent of rotational movement of the clamping arm, the opposite longitudinal edges of the keyway serving as abutment surfaces against which the key respectively abuttingly engages when the clamping arm is in the fully retracted or extended position. This feature avoids the need to provide stop surfaces on the frame of the fitting being installed.

Preferably, the clamping arm is curved whilst the locking arm is essentially shaped.

Preferably, each of the arms is integrally moulded of suitable plastics material.

*e too*$ Preferably, the locking arm is provided with snap-off sections for the purpose of length adjustment which allows the arm to be used with a wide variety of fittings or components being mounted to the wall.

S. Preferably, the locking arm has a spring clip arrangement which is designed to maintain a constant pressure on the clamping arm, whereby as the clamping arm, during tightening of the fastening screw, rides up the mounting stem of the locking arm, the locking arm is held against the rear surface of the fitting or component being installed.

OS 0 The present invention is especially suitable for mounting electrical fittings such as switches or power outlets which comprise a facia plate and a mounting plate which carries the switch or power outlet socket, the mounting plate having a surface area which is slightly smaller than that of the facia plate, with the body of the switch or outlet socket projecting inwardly through the opening in the wall. The facia plate is clamped against the wall by means of a pair of mounting devices of the present invention, one on each side of the mounting plate, clamping screws passing through holes in the facia plate which align with the axial bores formed in the telescopically engaging mounting stems of the arms. The 4 screws are then turned to rotate the clamping arms to their extended positions, further tightening of the screws drawing the arms into clamping engagement against the rear surface of the wall.

In order to more fully explain the present invention, an embodiment is described hereunder in some further detail with reference to the accompanying drawings wherein: Fig. 1 is an exploed perspective view of the mounting device according to this invention, 10.. Fig. 2 is a rear elevational view showing a wall mounted *l electrical switch plate mounted to a wall using the mounting 0S devices of the present invention; @00* Oe Figs. and and Figs. and are elevational views of the locking and clamping arms respectively of the mounting device shown in Fig. 1; and i ee•Figs. and show the manner of installation of the mounting device of this invention.

Referring to the drawings, the invention is described in relation to a wall mounted electrical switch assembly which comprises a plastic facia plate 10, an electrical switch 11, having a plastic switch body 13 which projects re6 4 w;udly of

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the facia plate 10. The switch 11 and facia plate 10 are secured together by a snap-fitting engagement but of course fastening screws may be used in lieu thereof.

The facia plate 10 is positioned over an opening in a wall 14 on which the switch plate assembly is desired to be mounted, with the switch body 13 projecting inwardly through the opening and into the cavity behind the wall 14.

A pair of mounting screws 17 project through holes 18 formed in the facia plate adjacent opposite sides thereof, each screw 17 supporting a mounting device 19 which forms the essence of the present invention.

Each mounting device 19 comprises a pair of movable arms 23 which are able to rotate relative to one another, the arm 20 constituting a locking arm whilst the arm 23 constitutes an outer clamping arm designed to clampingly engage against a marginal edge portion of the wall opening, whilst the inner arm 20 is arranged so that its distal end abuts against an engagement surface on the switch 11. Each arm 20,23 is provided with a mounting stem 24,25 respectively having an axial bore 26,27 extending therethrough, the bores 26,27 S. having a common axis which is coincident with the axis of the

S..

S associated fastening screw 17.

In this embodiment, mounting stem 24 of arm 20 is slidably 01i: located within the bore 27 of stem 25 of the clamping arm 23, with the screw 17 passing through the bore 26 of stem 24 and in turn through a small diameter hole 30 in the distal end 31 of stem 25. The diameter of the bore 26 is chosen so that a. S the threaded shank of the scre,, 17 can pass therethrough with a clearance fit, whilst the small diameter passage 30 at the distal end 31 of stem 25 is dimensioned so that the thread on the shank of the screw 17 makes screw contact with passage wall. With this arrangement, as the screw 17 is turned, the rotation of the shank will in turn cause the clamping arm 23 to also rotate once the threaded shank makes engagement with the small diameter outlet hole In order to limit the extent of relative rotational movement between the arms 20,23, the bore 27 of stem 25 is provided with an axial key 32 which cooperates with an arcuate keyway 33 formed on the outer surface of stem 24. It will be appreciated that the extent of arc movement of the clamping arm 23 is dependent upon the circumferential extent of the curved keyway 33, the axial edges 35,36 which border the keyway 33 constituting stops against one of which the key 32 abuts when the arm 23 is in its retracted or extended position.

When the electrical fitting is being installed in the opening in the wall 14, the arms 20,23 are positioned so that they both extend to one side of the shank of the screw 17, i.e. in the direction of the switch 11, with the key 32 of stem abutting against edge 36 of keyway 33. The free end of the locking arm 20 is arranged to abut against an engagement surface either on the switch 11 or on the rear surface of the plate 10 so that, when so engaged, it is inhibited against rotation in the tightening direction of the screw 17. With the locking arm 20 thus locked, turning of the screw 17 causes the clamping arm 23 to rotate from a retracted aOf. position wherein it lies inboard of the facia plate 10 to an S extended position wherein its distal end portion locates behind an inner marginal edge portion of the opening in the wall 14. Further tightening of the screw 17 draws the clamping arm 23 into clamping engagement against the marginal edge portion of the hole 14, the arm 23 being restrained *fee against any further rotational movement in the tightening direction of the screw by virtue of the abutting engagement between the key 32 and edge 35 of keyway 33.

With the screws 17 thus so tightened, the facia plate is **gO securely mounted to the wall 14.

In this embodiment each of the arms 20,23 is an integral "i moulding of suitable plastics material. However, it will be realised that the each of the arms need not be integrally moulded and that the mounting stem may be separately formed from the arm component.

Referring to Fig. 3(a) of the drawings, the stem 24 of the inner arm 20 is provided with an axially extending resilient finger 38 which grippingly engages against the bore surface of bore 27, and serves as a spring clip in order to maintain a constant pressure on the swinging clamping arm.l 23, when the stems 24,25 are interengaged. This ensures that as the clamping arm 23 rides up the outer tubular wall of the stem 24, the locking arm 20 is held firmly against the back 7 surface of the facia plate 10. This will ensure that the free end of the inner arm 20 will remain engaged against an engagement or abutment surface on the rear side of the facia plate 10 and hence be restrained against axial displacement which might otherwise cause the arm 20 to disengage from its locked position.

Preferably, the clamping arm 23 is provided with serrations or teeth near to or at its free end which are designed to bite into the _-ear surface of the wall 14, thereby improving the gripping engagement of the clamp arm 23 against the wall surface when in its fully tightened clamped position.

S Preferably, the arm 20 is provided with a plurality of S breakaway or snap-off sections 39,39' so that its length can be selected as desired, thereby allowing the arm to be used with a wide variety of electrical accessory plates and fittings. The arm need not necessarily be of angle epee configuration as shown in Fig. 3(a) but rather may be a simple linear arm which extends radially from the shank of *-the fastening screw 17.

A brief consideration of the abovedescribed embodiments will 6*WS :indicate that the invention provides for a very simple and inexpensive hollow wall mounting device which eliminates the need for wall boxes, mounting plates, bracketry etc. which S: are normally placed behind the wall during construction thereof. It should also be appreciated that the mounting device of the present invention is not necessarily limited to the mounting of electrical wiring fittings but can easily be adapted for use with other objects and items which are designed to be mounted in an aperture or opening in a hollow wall or a wall panel.

Claims

2. An improved hollow wall mounting device according to claim 1 wherein the bore of the mounting stem of the clamping arm is sized so as to slidably snugly receive the mounting stem of said locking arm, the length of the mounting stem of the clamping arm being slightly greater than that of the mounting stem of the locking arm.
3. An improved hollow wall mounting device according to either claim 1 or claim 2 wherein said limit means are integrally formed with said mounting stems. 9
4. An improved hollow wail mounting device according to claim 3 wherein said limit means ci mprises an internal key extending axially along the bore of the stem of the clamping arm, and a semi-circular keyway on the outer surface of the stem of said locking arm, said key and keyway co-operating together to limit the extent of rotational movement of said clamping arm. An improved hollow wall mounting device according to any one of the preceding claims wherein said clamping arm is curved in plan. I. S 6. An improved hollow wall mounting device according to any *d one of the preceding claims wherein said locking arm is approximately L-shaped.
7. An improved hollow wall mounting device according to any one of the preceding claims wherein said locking arm is provided with breakaway arm portions to enable the effective length of the arm to be adjusted during the mounting procedure.
8. An improved hollow wall mounting device according to any one of the preceding claims wherein the mounting stem of said locking arm is provided adjacent its distal end with an S axially extending resilient flexible finger in its outer wall surface which, when the stems are slidably interengaged, makes pressure contact with the bore surface of the mounting stem of the clamping arm.
9. An improved hollow wall mounting device according t- any one of the preceding claims wherein each said arm anu its mounting stem is integrally moulded of synthetic plastics material. An improved hollow wall mounting device according to any one of the preceding claims wherein said locking arm is I- arranged so that its distal end, during the tightening of the fastening screw, bears against an engagement surface on the rear wall of paid object, said locking arm being restrained against rotation in the screw tightening direction by virtue of its engagement with said engagement surface.
11. An improved hollow wall mounting device according to any one of the preceding claims wherein the distal end of said clamping arm is provided with serrations or teeth arranged to bite into the rear surface of the wall for enhancing the gripping engagement of the clamping arm against the wall surface when in its fully tightened extended position. St 0e S 12. An improved hollow wall mounting device according to any one of the preceding claims wherein said object is an electrical wiring accessory mounting plate. J 4o
13. An improved hollow wall mounting device substantially as P** hereinbefore described with reference to and as illustrated in the accompanying drawings. 0* OS Dated this 2nd day of September 1993. GERARD INDUSTRIES PTY LTD By its Patent Attorneys R K MADDERN ASSOCIATES S ^p A BSTRACT This invention relates to a hollow wall mounting device (19) for releasably mounting an object in an opening in the wall, the device comprising a pair of co-operable relative rotatable arms (20, 23), one arm (20) constituting a locking arm with the other arm (23) constituting a swinging clamping arm designed to clampingly engage against a marginal edge portion of the wall opening, the arms (20, 23) having hollow mounting stems (24, 25) which slidably locate one within the other, a fastening screw (17) extending through the interengaging hollow stems (24, 25), and limit means (32, 33) on the stems (24, 25) for limiting the extent of rotational movement of the clamping arm (23) which is constrained to swing between a retracted position wherein it lies to the same side of the locking arm (20) and an extended position where it projects to the side opposite to that of the locking arm arranged so that upon initial tightening of the screw the clamping arm (23) is rotated to an extended position wherein it is locked against rotational movement in the tightening direction of the screw whilst further tightening of the screw (17) causes the arm (23) to assume its clamping position.