AU653280B2 - A light fitting apparatus - Google Patents

Description

6 r) Lhr~i 80 S F Ref: 220564

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

I -I S S *4 Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: p. *r

S.

I S Roy Michael Halle 137A Victoria Road Bellevue Hill New South Wales 2023

AUSTRALIA

Roy Michael Halle Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia A Light Fitting Apparatus ASSOCIATED PROVISIONAL APPLICATION DETAILS [31] Application No(s) [331 Country PL0018 AU PL0314 AU [323 Application Date 13 December 1991 8 January 1992 The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5815/5 The present invention relates to underwater pool lights and, in particular to an underwater pool light fitting having electrical connections which prevent ingress of water into the light fitting.

Existing pool light fittings which are placed under water level have an electrical cable gland which is the aperture through which the electrical cable passes. A gland is used to clamp the electrical cable to provide a substantially air-tight seal.

A major failing of the supposedly air-tight seal is that when the light is switched on, the air within the lamp sealed volume heats up and therefore pressure within the light fitting increases. The extra pressure within the light fitting due to the heating and expansion, causes air to escape from the light fitting through the gland which is supposedly air-tight. This process may occur over a long period of time as the elasticity of the plastics in the electrical cable can deteriorate at the gland.

"i As the air is slowly escaping from within the light fitting, the negative pressure or partial vacuum within the light fitting when the light is switched off, becomes substantially stronger until a situation is reached where the negative pressure is such that water is sucked into :m 20 the light fitting. Such a situation is undesirable as the light fitting tends to deteriorate with the water inside thereof.

It is an object of tlhe present invention to provide an improved light fitting apparatus which substantially overcomes or ameliorates the above mentioned disadvantages.

i 25 According to one aspect of the present invention there is disclosed a light fitting apparatus Including a sealed volume within which a lamp is locatable, an aperture which connects said sealed volume and exterior of said light fitting, said aperture having an electric cable attached thereto with sealing means to seal said aperture around the exterior of said electric cable, wherein said apparatus includes an expansion chamber means in fluid communication with said sealed volume to receive air which expands from said sealed volume as pressure within the sealed volume rises, wherein said air returns to the sealed volume from said expansion chamber as the pressure within said sealed volume falls, and wherein said expansion chamber means is located in said electrical cable which communicates with said sealed volume via said aperture.

Some embodiments of the present invention will now be described with reference to the drawings in which: S H'I/0603c

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a a a a Fig. 1 is a cross-sectional side view of a light fitting apparatus of a preferred embodiment, Fig. 2A is a rear view of a backplate of the apparatus of Fig. 1, Fig. 2B is a side view of the backplate of Fig. 2A, Fig. 2C is a cross-sectional view along the lines C-C of Fig. 2A, Fig. 3 is a side view, partly in section, of an electrical cable of the apparatus of Fig. 1, and Fig. 4 is a cross-sectional side view of the apparatus of another arrangement.

The apparatus of a preferred embodiment includes a light fitting 1 which is locatable on a side wall of a swimming pool (not illustrated).

The light fitting 1 includes a sealed volume 2 between a lens 3 and a backplate 4. The lens 3 is securable to the side wall by bolts (not illustrated). The lens 3 has a flow through anti skirt rim 5 adjacent the side wall. A lamp 6 is positioned in the sealed volume 2 to provide light in the swimming pool. The sealed volume 2 is sealed to prevent ingress of water so that the lamp 6 operates efficiently.

The backplate 4 has an aperture 7 located in a stepped portion 8.

A gland 9 is sealingly fitted to the aperture 7 on the outside of the sealed volume 2. The gland 9 has an internally threaded portion 10 which mates with an externally threaded portion 11 of a gland nut 12 (Fig. 3).

The gland nut 12 is part of an electrical connector 13 attached to an electrical cable 14. The connector 13 fits into the gland 9 as illustrated in Fig. 1 and is screwed into position, and the lamp 6 is pushed into contact with the electrical contacts (not illustrated) of the connector 13.

The connector 13 has pair of rings 15 to maintain the seal of the sealed volume 2. The electrical connector 13 has connected thereto the electrical cable 14 which includes an active wire 16 and a neutral wire 17. The electrical cable 14 has its outer sheath 18 removed adjacent the electrical connector 13. A flexible tube 19 is fitted over the exposed active and neutral wires 16 and 17 between the electrical connector 13 and end 20 of the of the outer sheath 18. the tube 19 is flexible and is sealed with an air-tight seal at the electrical connector 13 as it is fitted over a plurality of ribs 21 of the connector 13 and is clamped by the gland nut 12. The tube 19 is sealed over the outer sheath S18 by means of a clamp 22.

~~1F/0603c As the tube 19 is flexible it is easily expanded when there is greater air pressure within the tube 19 than outside the tube 19. The tube 19 effectively acts as an expansion chamber.

In operation, as the air within the sealed volume 2 heats due to the operation of the lamp 6, the air pressure within the sealed volume 2 rises substantially. As this pressure rises, air is able to escape from within the sealed volume 2 through the electrical connector 13. The air flows through the electrical connector 13 into the tube 19. As the tube 19 is clamped securely at both ends thereof, the air remains within the tube 19 and is not allowed to escape. When the lamp 6 is switched off, and the air within the sealed volume 2 cools, the pressure within the sealed volume 2 falls. The air within the tube 19 then flows back through the electrical connector 13 and aperture 4 into the sealed volume 2 of the light fitting 1. This means that the air within the sealed volume 2 of the light fitting 1 does not leak out of the light fitting 1.

This prevents the ingress of water which presently occurs in existing light fittings.

Another arrangement is illustrated in Fig. 4. In this arrangement a light fitting 31 includes a sealed volume 32 between a lens 33 and a 20 backplate 34. The light fitting is similar to the previously described embodiment except that the expansion chamber is attached directly to the backplate 34. The expansion chamber has a flexible, bladder-like membrane tube 35 clamped to a gland 36 which screws onto an aperture 37 in the rear surface of the backplatA 34. The tube 35 expands or retracts as necessary as the ai iressure with the sealed volume 32 changes.

The foregoing describes only one embodiment of the present invention, and modifications obvious to those skilled in the art can be S: made thereto without departing from the scope of the present invention.

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Claims (8)

1. A light fitting apparatus including a sealed volume within which a lamp is locatable, an aperture which connects said sealed volume ant exterior of said light fitting, said aperture having an electric cable attached thereto with sealing means to seal said aperture around the exterior of said electric cable, wherein said apparatus includes an expansion chamber means in fluid communication with said sealed volume to receive air which expands from said sealed volume as pressure within the sealed volume rises, wherein said air returns to the sealed volume from said expansion chamber as the pressure within said sealed volume falls, and wherein said expansion chamber means is located in said electrical cable which communicates with said sealed volume via said aperture.

2. Apparatus as claimed in claim 1, wherein said expansion chamber means includes a hollow flexible tube portion which lies longitudinally within said electrical cable.

Apparatus as claimed in claim 2, wherein said flexible tube portion is adjacent an electrical connector which connects said cable to said aperture.

4. Apparatus as claimed in claim 3, wherein said connector sealingly fits into a gland which is sealingly fitted to said aperture, and said lamp fits into said electrical connector.

Apparatus as claimed in claim 1, wherein said expansion chamber further comprises a flexible membrane sealingly clamped to an opening in a surface of said sealed volume.

6. Apparatus as claimed in claim 5, wherein said opening is located in a backplate at the rear of said sealed volume.

7. Apparatus as claimed in claim 5 or 6, wherein said membrane :has a closed bladder-like structure and is clamped to a gland which is sealingly screwed to said aperture.

8. A light fitting apparatus substantially as described with reference to Figs. 1-3 or Fig. 4 of the accompanying drawings. DATED this THENTY-FIRST day of JULY 1994 Roy Michael Halle Patent Attorneys for the Applicant SPRUSON FERGUSON HRF/0603c A Light Fitting Apparatus ABSTRACT A light fitting apparatus for a swimming pool is disclosed. The apparatus includes a light fitting with a sealed volume between a lens and a backplate A lamp is positicied within the sealed portion An electrical connector (13) is sealed into a gland (9) which fits into an aperture in the backplate An electrical cable (14) which is used to supply power to the lamp includes a flexible tube (19) which acts as an expansion chamber to receive air which escapes from said sealed portion through the connector when pressure within the sealed portion rises. The air is then able to be returned to the sealed volume via the connector (13) when the pressure within the sealed portion returns to normal. Alternatively, a flexible bladder (35) is provided in communication with the sealed volume eq Fig. 1 .o C.. HRF/STA/0603c