AU726122B2

AU726122B2 - Protected switch

Info

Publication number: AU726122B2
Application number: AU23513/97A
Authority: AU
Inventors: Hargopal Verma
Original assignee: HPM Industries Pty Ltd
Current assignee: HPM Industries Pty Ltd
Priority date: 1996-06-25
Filing date: 1997-05-20
Publication date: 2000-11-02
Anticipated expiration: 2017-05-20
Also published as: AU2351397A

Description

1 P/00/0 1 1 Regulation 3.2

AUSTRALIA

Patents Act 1 990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT

S

S. S S S

S.

Invention Title: PROTECTED SWITCH The following statement is a full description of this invention, including the best method of performing it known to us: GH REF: P04210-VC/RW:SD -2- This invention relates to a switch which is protected against ingress of moisture and, in particular, to a switch that is intended to be used in wet areas, such as in bathrooms and laundries where the presence of moisture may expose a person who operates a switch to a risk of electrocution. The switch may be used alone, for example as a light switch, or it may be employed in conjunction with a switched power outlet socket.

A switch may be protected against the entry of moisture simply by locating it in a weatherproof enclosure and providing an appropriate external operator. However, it is desired by architects, builders and householders that moisture protected switches should "look" the same as conventional switches and the present invention is directed to a switch arrangement that has the external appearance of a conventional wall or architrave mounted *e switch.

S"Various switches have been developed to meet this criterion, for example those which are disclosed in French Patent No. 1222137, German Offenlegungsschrift 27 49 829 and British Patent No. 2044003.

A switch of the type that is more closely related to that of the present invention is disclosed in International Patent Application No. PCT/NZ95/00078 (Publication No. W096/08024), dated 30 August 1995, which has been pursued in Australia under Application No. 33573/95. That application discloses a switch which comprises a mounting plate, a switch rocker pivotably mounted to the mounting plate, a so-called control member formed integrally with and extending rearwardly of the switch rocker, a switch module having moving and fixed contacts mounted to the rear side of the mounting plate, and a diaphragm located between the mounting plate and the switch module. The diaphragm is formed with an aperture through which the control member projects, and the control member carries a switch actuator which functions to cause 0421 3 switching movement of the moving contact with operation of the switch rocker.

It is expected that the above described switch will perform adequately when new, but it is also expected that constant operation of the switch will in time cause damage to the diaphragm in the region where the control member protrudes through the diaphragm. An attempt has been made to minimise the effect of this problem by positioning the region at which the control member protrudes through the diaphragm in line with the pivot axis of the switch rocker.

However, with constant relative movement between the control member and the diaphragm, however small, it is expected that a moisture path will be established through the aperture within the diaphragm.

15 The present invention seeks to avoid the above problem by providing a switch arrangement which comprises a mounting plate having a forward face and an aperture formed in the forward face, a switch actuating rocker pivotably mounted with respect to the mounting plate and positioned within the aperture, and a switch module mounted to the rearward side of the mounting plate. The switch module incorporates fixed and movable contacts and has a pivotable .switch actuator arranged, when pivoted, to act on the movable contact. The switch arrangement is characterised S 25 in that: a drive element is coupled to the rearward side of the rocker and extends between the rocker and the switch actuator for the purpose of transferring pivotal motion of the rocker to the switch actuator, a recess is formed in the switch actuator and is arranged and positioned to receive a free end of the drive element so that, when the rocker is pivoted in one direction or the other, the drive element will impart reverse direction pivotal movement to the 44 35 actuator, and 04210-VC -3A a membrane is secured to the rearward side of the mounting plate and is formed so as to locate between the drive element and the rocker, to thereby provide a barrier to movement of moisture between the rocker and the switch module.

The rocker preferably is formed on its rearward side with a recess and in such case the drive element will be o oo a o• a a a a *o o o• 0421 0-VC 4 shaped to locate within and extend outwardly from the recess. Also, the membrane preferably is formed with a pocket which is arranged to receive one end portion of the drive element and to locate within the recess. With this arrangement, the drive element functions to hold the pocket portion of the membrane in the recess, so that the retained part of the membrane effectively forms a part of the coupling between the drive element and the rocker.

The switch module is preferably mounted to the rear of the mounting plate by way of a moulded carrier, and the carrier preferably is arranged to clamp the membrane to the rearward side of the mounting plate.

The invention will be more fully understood from the S. following description of a preferred embodiment of a eeeoo 15 switch arrangement. The description is provided with e.

e reference to the accompanying drawings in which: Figure 1 shows a sectional elevation view of a portion of the switch arrangement, Figure 2 shows a view of a portion of the switch 20 arrangement as illustrated in Figure 1 but in a different switching position, ~Figure 3 shows a plan view of the rearward side of the switch arrangement, as viewed in the direction of arrow 3 shown in Figure 1, eooe Figure 4 shows a sectional side elevation view of a membrane component of the switch arrangement, and Figure 5 shows a plan view of the membrane.

As illustrated, the switch arrangement comprises a moulded plastics material mounting plate 10 which has a forward face 11. The forward face is covered by a removable plastics material cover plate 12.

An aperture 13 is formed within the forward face of the mounting plate, and a moulded insert 14 is positioned within the aperture. The insert is held in place by integrally formed projections 04210-VC 5 A switch actuating rocker 16 is mounted to the mounting plate 10 by way of the moulded insert 14. The rocker 16 is pivotably mounted to the insert and is arranged to pivot overcentre from the position shown in Figure 1 to that shown in Figure 2.

The rocker 16 is formed on its rearward side with an integrally moulded cylindrical wall 17 which defines a recess 18, and a moulded pin-like drive element 19 is located within and projects outwardly from the recess.

A switch module 20 is mounted to the rearward side of the mounting plate 10 by way of a moulded carrier 21. The carrier 21 is secured to the mounting plate 10 by screws 22 and the switch module 20 is held captive to the carrier by moulded projections 23.

The switch module has a more-or-less conventional construction and it comprises a moulded, generally cylindrical body 24 which contains fixed and moving contacts (not shown). A switch actuator 25 is pivotably mounted to the body 24 and, although not so shown in the 20 drawings, the actuator 25 functions when pivoted to move the moving contact into engagement with one or the other of two fixed contacts.

The actuator 25 is formed with a recess 26 which receives a free end of the drive element 19. When the 25 rocker 16 is pivoted in one direction or the other, the drive element 19 imparts reverse-directional pivotal movement to the actuator A moulded membrane 27 is positioned between the rocker 16 and the switch module 20 for the purpose of precluding the movement of moisture between the rocker and the switch module. The membrane 27 is moulded from a resilient synthetic rubber material and is clamped in position between the rearward side of the mounting plate 10 and the carrier 21.

As is best seen from Figure 4 of the drawings, the membrane 27 is formed with a thin-walled central region 0421 O-VC 6 which includes a well portion 28 and a central pocket 29.

The pocket 29 is shaped and sized to locate within the recess 18 of the rocker 16, and the well portion 28 accommodates local flexing of the membrane with pivotal movement of the rocker 16.

The drive element 19 is a press fit within the pocket 29 and, when fitted into the recess 18, serves to hold the membrane 27 captive to the rocker. Thus, the membrane is located between the drive element 19 and the rocker 16 and it serves to provide a permanent barrier to the movement of moisture between the rocker 16 and the switch module The barrier is preserved regardless of the pivotal position of the rocker.

e 0421 0-VC

Claims

2. The switch arrangement as claimed in claim 1 go wherein the rocker is formed on its rearward side with a recess and wherein the drive element locates within and extends outwardly from the recess.
3. The switch arrangement as claimed in claim 2 wherein the membrane is formed with a pocket which is arranged to receive one end portion of the drive element and which locates within the recess.
4. The switch arrangement as claimed in claim 3 wherein the drive element functions to retain the pocket R/ portion of the membrane in the recess and wherein the 0421 0-VC -8- retained pocket portion of the membrane effectively forms a part of the coupling between the drive element and the rocker. The switch arrangement as claimed in any one of the preceding claims wherein the switch module is mounted to the rear of the mounting plate by way of a moulded carrier, and wherein the moulded carrier is arranged to clamp the membrane to the rearward side of the mounting plate when the moulded carrier is secured to the mounting plate.
6. The switch arrangement as claimed in claim 3 or claim 4 wherein the membrane is formed with a thin-walled central region which includes a central well and wherein the pocket of the membrane is formed as a projection of the 15 central well.
7. The switch arrangement as claimed in any one of claims 3, 4 or 6 wherein the drive element comprises a pin- o like element which is sized and arranged when located within the membrane pocket to provide the membrane pocket with a cross-sectional dimension that is a press-fit within O0 the rocker recess. ooo
8. A switch arrangement substantially as shown in olo• the accompanying drawings and substantially as hereinbefore described with reference thereto. DATED this 21st day of AUGUST 2000 H.P.M. INDUSTRIES PTY LIMITED By their Patent Attorney GRIFFITH HACK 0421 O-VC