NZ218564A - Snap-in flush mount switch - Google Patents

Description

218564 NEW ZEALAND PATENTS ACT, 1953 No.: 218564 Date: 9th December 1986 COMPLETE SPECIFICATION "Improvements in/or relating to electrical switch gear" I, 2Q/We, PPL HOLDINGS LIMITED, a New Zealand company, of 14 Hazeldean Road, Christchurch, New Zealand hereby declare the invention for which^I / we pray that a patent may be granted toXXe/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - 218564 This invention relates to a switching assembly.

Domestic and light industrial switches are mounted in a mounting plate which is fixed to a box located in a wall or similar structure. It is sometimes desirable to have a facility whereby the switch modules can be removed from the mounting plate. With the existing designs of such module switches at present available, the module unit is mounted from the rear of the plate. These switch modules clip into place in an aperture in the mounting plate but because of the rear loading, any significant force applied to the front of the switch may cause the switch module to disengage from the plate. To provide suitable protection against this occurrence, additional fixing means, usually in the form of screws, are inserted. This means of mounting is not entirely satisfactory both because the unit is still subject to displacement by heavy front loading particularly impact loading and in any event, the switch modules can be comparatively easily removed by an unauthorised person with the use of a simple tool such as a screwdriver blade.

It is proposed with the present invention to provide a front mounting switch module. This will mean a construction that is better designed to resist displacement from impact on the face of the switch. As an ancillary feature, it is intended to provide a mounting which will be difficult to disengage without the assistance of a module ejector. This will tend to ensure only qualified tradespersons are able to remove the switch modules from the mounting plate.

In the specification the "switch module" it is intended to encompass the housing in which will hold the switch components or other ancillary equipment that can be used on a mounting plate. As an example of such ancillary 218564 m equipment, it is intended to include a neon unit, a press switch, an n infra-red controlled switch, a cord outlet, an attachment for a hi-fi speaker or television aerial, a fused unit, a pull cord switch and a cord outlet. These are intended to be illustrative and not exhaustive of the type of ancillary equipment that can be mounted in a housing module for use in association with the mounting plate. Also it would be part of the design to provide a blank which can be used to fill an opening in a plate where no switch module or ancillary unit is to be used.

Accordingly the present invention consists in a flush mounted electrical switch assembly comprising a mounting plate defining an opening to receive and mount a removable switch module and a removable switch module having a housing with mounting means to locate and engage said module in said opening in the mounting plate, characterised in that members on opposite sides of the opening each project into the opening in the mounting plate, the top surfaces of the members defining a common plane recessed below the v.- top face of the mounting plate, the bottom surfaces of the members defining shoulders on opposite sides of the opening and in that the mounting means of the switch module housing includes a peripheral lip at the top of the housing to engage in the opening in the mounting plate with the bottom face w of the lip resting on the top surfaces of the members, and mounting arms extending on opposite sides of the housing up from the base of the housing, said arms being resiliently deformable when the module is inserted in the opening from the top face of the plate to pass the projecting members and spring back to engage the shoulders formed thereby-to hold the switch module in place in said mounting plate. \ 218564 - 3a - ^ One preferred form of the invention and a modification thereof will now be described with reference to the accompanying drawings in which: Figure 1 is a diagrammatic view showing part of the mounting plate with the switch module ready to be inserted therein, G 218564 Figure 2 shows the switch module partially inserted in the mounting plate, Figure 3 shows the switch module inserted in place, Figure 4 shows a partial sectional view through one side of the opening in the mounting plate and the corresponding part of a modified switch module when the switch module is partially in place, and Figure 5 shows the alternate form of the invention when the switch module is fitted in place.

In the preferred form of the invention a switch module 1 is constructed so that it contains the necessary electrical componentry and as has been previously explained it is intended in this specification that the term "switch module" should be interpreted to include other ancillary equipment which may be usefully mounted in a mounting plate.

The housing 2 of the switch module is a moulded plastic housing preferably moulded from some suitable grade of plastic, normally a suitable nylon. The housing 2 contains the switch components. These are not illustrated in the present drawings but are described and claimed in our New Zealand Patent Specification No. 218565.

The mounting plate 3 is a normal flush mounting plate designed to be attached to a box fixed in a wall or similar structure in accordance with the requirements of the regulatory authority in the country concerned. The plate may have one or a plurality of apertures each to receive a switch module and these apertures can be arranged in any convenient pattern. 218564 Each opening 4 has a peripheral recess 5 extending in from the top face 6 of the mounting plate. Throat members 7 below the recess 5 project into the opening 4 creating shoulders 8 on the under surface thereof. A skirt 9 projects down from the under surface of the plate.

The housing 2 has a top lip 10 designed in use to engage in the recess 5 so that the top of the switch module will be flush or substantially flush with the top 6 of the plate 3 as is illustrated in Figure 3. The housing below the lip 10 is cut away with resilient arms 11 and 12 rising upwardly and extending outwardly from the base of the housing. The top 13 of the arms 11 and 12 is arranged in use to engage beneath the shoulder 8 when the module is fitted in place again as is illustrated in Figure 3.

The switch module is inserted from the front of the plate 3. The throat members 7 compress the resilient arms 11 and 12 as is illustrated in Figure 2. The switch module when inserted fully as shown in Figure 3 allows the arms 11 and 12 to spring back with the ends 13 under the shoulders 8. The arms are preferably still slightly compressed to assist in firmly holding the switch module in place. Preferably two arms are provided on each side of the switch. This is not critical but it is a more desirable configuration.

When it is necessary to remove the switch module from the mounting plate, a module ejector is employed. This comprises a substantially square socket having a skirt designed to engage with the arms 11 and 12. The arms have an inclined face 14 which will be engaged by the skirt of the ejector. As the skirt is moved up the incline, it will move into the space defined by the skirt 9 dependent from the mounting plate 3. The skirt of the ejector can be comparatively thin because when it moves into association with the skirt 9 it v . wr,, 2185^4 is supported and further movement upwardly causes the ejector skirt to compress the resilient arras 11 and 12 to a configuration essentially as illustrated in Figure 2 thereby allowing the switch module to be moved from the mounting plate. While a comparatively simple form of ejector is able to remove the switch module, it is a specialist tool and without that specialist tool it would be very difficult to remove the switch module from the mounting plate.

The preferred form of invention described above has certain advantages in that it allows a material to be selected which is not subjected to any significant stress during use but it does require a tolerance in manufacture and does not allow any adjustments in thickness of the switch mounting plate. In certain cases where a degree of adjustment is desirable or the stress loading applied to the material was not considered so critical or special material was available to withstand high stress loading, a construction as illustrated in Figures 4 and 5 could be employed.

In this instance, the mounting plate 3, throat members 7, recess 5, shoulders 8 and skirt 9 are the same as previously described. In the case of the housing 2 the resilient mounting arm 12a has a different configuration at the head 15. The head 15 has a serrated or stepped upper surface 16. In this instance because of the serrated upper surface 15 there would be a range of positions where the switch unit could be engaged with the shoulder 8. As will be seen from the configuration adopted in Figure 4, the head 15 is deformed substantially to allow a disposition to be assumed which will enable the head to pass the throat members 7. This deformation stresses to a substantial degree the material in the arm 3 and it is for this reason that care needs to be exerted in selecting the material if such a configuration is adopted. 2185^4 With the present invention either mode of the switch module can be inserted into the mounting plate from the front to provide an aesthetically pleasing and very strong assembly.

In use, a tradesperson has the capacity to easily remove the switch module so that it can be replaced if defective. It can be adjusted in position, it can be replaced by one of the ancillary units, it can have a blank inserted where it had been removed or it can be inserted in position where a blank was previously fitted. There is thus a great range of flexibility and a strong safe assembly is provided. From a practical point of view, the above described construction has the advantage that it can be manufactured using simpler dyes on the plate section because there are not undercut areas needed to provided the retention legs as are necessary with rear mounted switch modules.

Claims (1)

1*;vl;218564;r> WHAT WE CLAIM IS:;1. A flush mounted electrical switch assembly comprising a mounting plate defining an opening to receive and mount a removable switch module and a removable switch module having a housing with mounting means to locate and engage said module in said opening in the mounting plate, characterised in that members on opposite sides of the opening each project into the opening in the mounting plate, the top surfaces of the members defining a common plane recessed below the top face of the mounting plate, the bottom surfaces of the members defining shoulders on opposite sides of the opening and in that the mounting means of the switch module housing includes a peripheral lip at the top of the housing to engage in the opening in the mounting plate with the bottom face of the lip resting on the top surfaces of the members, and mounting arms extending on opposite sides of the housing up from the base of the housing, said arms being resiliently deformable when the module is inserted in the opening from the top face of the plate to pass the projecting members and spring back to engage the shoulders formed thereby to hold the switch module in place in said mounting plate.;2. A flush mounted electric switch assembly as claimed in Claim 1 wherein two mounting arms are arranged on each side of the housing.;3. A switch assembly as claimed in Claim I or Claim 2 wherein each mounting arm is integrally moulded with the housing and extends upwardly_and^outward;Nw*"' x> • " 218564 I (Tx< ,,, f - 9 - from the base of the housing to terminate in an end designed to engage a shoulder in the mounting plate. 4. A switch assembly as claimed in Claim 1 or Claim 2 wherein each mounting arm terminates in a head having a series of serrations or indentations on a top face thereof to allow for engagement in one of a plurality of positions with a shoulder in the mounting plate. 5. A switch assembly as claimed in any one of the preceding claims including a dependent skirt projecting from the under surface of the mounting place around the periphery of the opening. 6. A flush mounted electrical switching assembly when constructed, arranged and operable substantially as herein described with reference to the O accompanying DAY0FO^«^ DATED a , pabK. & S0N AGENTS FOR THE~APPU£^I§i