FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Modular enclosure for holding Printed Circuit Boards APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai - 400 030, Maharashtra, India, an Indian Company
INVENTOR
Sathe Mahesh of Crompton Greaves Ltd, Industrial Design Centre, Global R&D, Crompton Greaves, Kanjurmarg (East), Mumbai - 400042 Maharashtra, India; an Indian National
PREAMBLE TO THE DESCRIPTION :
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

Field of the Invention:
This invention relates to the field of mechanics.
Particularly, this invention relates to the field of extruded mechanical assemblies.
Still particularly, this invention related to a modular enclosure for holding Printed Circuit Boards.
Background of the Invention:
Printed Circuit Boards (PCB) revolutionalised the world of electronics by providing a single flat board with electronic components soldered on to them, and tracks embedded onto said PCBs to interconnect said soldered electronic components. Typically, a PCB is a quadrangular board with a length side and breadth side. The height of the electronic components soldered on to the PCB defines the height of the PCB, in general.
Advancements in the field of electronics necessitated use of multiple PCBs for one single assembly, and required the need to house said multiple PCBs together. The limitations of installing multiple PCBs together lies in overcoming electromagnetic interference (EMI) problems with respect to two adjacently located PCBs. A housing was designed to hold such PCBs together. A general limitation of the housing was to handle thermal loads of every PCB and to provide adequate EMI / RF shielding.

Typical enclosures include the design of a rectangular box (cuboid) with an open entry side. There were provided slots to receive the PCB, said slots being defined in their gap in relation to thickness of said PCB. Also, in order to eliminate thermal overload and electromagnetic interference as discussed above, the PCBs were spaced apart at a pre-defined (particularly, greater) distance. The PCBs are generally slid in and out of the slots. Typical enclosures may relate to sub-assemblies hosting electronic sub-assemblied within a larger assembly housing.
Normally EMI/RFI shielding is achieved by thin metallic sheet which sometimes creates trouble while servicing the electronic sub assemblies.
There is a need to provide IP65 protection for such housings. IP65 housing ensures that no dust enters the housing and that water projected (by a 6.3mm nozzle) on the housing, from any direction, does not have any harmful effect i.e. by way of ingress within the housing.
There is a need for a better enclosure for PCBs.
Prior art
Prior art enclosures were made of a combination of plastic and metal which does not provide full EMI / RF shielding.

US6259173 discloses a Modular protective relay with submodules. A protective relay having internal processing circuitry embodied by removable and replaceable modules. Each module includes a main circuit board having common circuitry and also includes removable and replaceable submodules which electrically connect with the main circuit board to perform specific functions. The protective relay can have its functions altered by replacing one or more modules or submodules. However, IP protection is not provided. Also, EMI/RF shielding is not fool-proof.
Objects of the Invention:
An object of the invention is to provide a modular enclosure for holding Printed Circuit Boards (PCB) with electronic components on them, which enclosure being adapted to provide at least IP65 protection.
Another object of this invention is to provide an enclosure with electromagnetic interference shielding.
Yet another object of the invention is to provide an enclosure with RF shielding.
Summary of the Invention:
According to this invention, there is provided a modular enclosure for holding a plurality of Printed Circuit Boards (PCB), said modular enclosure

being adapted to provide EMI / RF shielding and IP protection, said enclosure comprises:
a. housing with extruded barrier sheets, each barrier sheet running along the
length and width of said housing, said barrier sheet being provisioned at
various intervals along the height of said housing to define gap shelves
between two consecutive barrier sheets, between a topmost barrier sheet
and the housing dorsal surface, and between a lowermost barrier sheet
and the housing ventral surface;
b. two lateral extruded sheets, a top extruded sheet, a bottom extruded sheet,
a front face extruded sheet, a back face extruded sheet adapted to form a
perimeter of said housing; and
c. mating mechanism at each location where the extruded sheets mate to
define said perimeter, said mating mechanism being defined by the
lateral extruded sheets including a top edge with a protruding edge
running along its length and further including a bottom edge with a
protruding edge running along its length, wherein slots are defined at the
lateral flanged ends of said operative horizontal top extruded sheet and
said operative horizontal bottom extruded sheet to receive said protruding
edges of each lateral extruded sheet, thereby locking said lateral extruded
sheets with said top extruded sheet and said bottom extruded sheet to
form a housing, and provisioning a gasket in the spaced apart gap
between said top end of protrusion edge and inner ventral wall of said
slot, wherein the winged portion of the protrusion edge and the winged
portion of the top edge extending thereof, mate with each other such that
they are in metal to metal contact.

Preferably, said gasket is a rubber gasket.
Particularly, said gasket is an O-ring
Typically, said housing includes slots along the inner lateral walls of the lateral extruded sheets in order to receive PCBs.
Typically, said housing includes a plurality of bolts through the flanges located at the lateral ends, beyond the slots of the top extruded sheet and bottom extruded sheet.
Brief Description of the Accompanying Drawings:
The invention will now be described in relation to the accompanying drawings, in which:
Figure 1 illustrates a schematic front cut section view of the modular enclosure;
Figure 2 illustrates a side view of the modular enclosure;
Figure 3 illustrates a side section view of the modular enclosure;
Figure 4 illustrates a top view of the modular enclosure; and
Figure 5 illustrates an isometric front section view of the modular enclosure.

Detailed Description of the Accompanying Drawings:
According to this invention, there is provided a modular enclosure for holding Printed Circuit Boards (PCB) in its operative configuration. Typically, said modular enclosure is adapted to provide EMI / RF shielding amidst providing IP65 protection.
Figure 1 illustrates a schematic front cut section view of the modular enclosure. Figure 2 illustrates a side view of the modular enclosure. Figure 3 illustrates a side section view of the modular enclosure. Figure 4 illustrates a top view of the modular enclosure. Figure 5 illustrates an isometric front section view of the modular enclosure.
In accordance with an embodiment of this invention, there is provided a housing with extruded barriers (12); each barrier running along the length and width of the housing. Said barriers are provisioned at various intervals along the height of the housing to define a gap between two consecutive barriers, between the topmost barrier and the housing dorsal surface (14), and between the lowermost barrier and the housing ventral surface (16). The housing includes two lateral extruded sheets (18), a top extruded sheet (14), a bottom extruded sheet (16), a front face extruded sheet (20), a back face extruded sheet (22) which forms its perimeter. It includes intermediate extruded sheets (12) which form the gaps or shelves within the housing.

In accordance with another embodiment of this invention, there is provided a mating mechanism (30) at each location where the extruded sheets mate to define the perimeter. The lateral extruded sheets (18) include a top edge with a protruding edge (32) running along its length and further includes a bottom edge with a protruding edge running along its length. The top extruded sheet (14) and the bottom extruded sheet (16) are operatively horizontal sheets. At their lateral ends, slots (34) are defined which receive the protruding edges (32) of each lateral extruded sheet (18). The slots (34) receive the protruding edges thereby locking the lateral extruded sheets (18) with the top extruded sheet (14) and the bottom extruded sheet (16) to form a housing. The operative top surface of the protruding edge (32) which slides into the slot (34) is spaced apart from the inner surface of the slot. A (rubber) gasket or an O-ring (rubber) (36) is placed in the spaced apart gap. The winged portion (32a) of the protrusion edge (32) and the winged portion (34a) of the top edge (34) extending thereof, mate with each other such that they are in metal to metal contact. This metal to metal contact provides a path for electromagnetic grounding and ensures that there is no residual electromagnetic / RF interference from the inserted PCBs.
The housing may further include slots (40) along the inner lateral walls of the lateral extruded sheets in order to receive PCBs (42).
The PCBs (42) are inserted in operative horizontal condition with EMI/RFI shielding, without need of development of special extrusion cross section or an extrusion die. According to the prior art, self tapping screw based end

covers were used for enclosing box extrusions which were not capable of offering IP 65 protection over a longer period of time. This drawback of prior art system has been overcome by having rugged bolting system. In accordance with an additional embodiment of this invention, there is provided a plurality of bolts (52) through the flanges (50) located at the lateral ends, beyond the slots (34) of the top extruded sheet (14) and bottom extruded sheet (16), The bolts (52) run through flanges of each of said barriers (12), thereby providing a firm enclosure. The bolts (52) provide a height adjustment mechanism as the flange of the barrier sheets may be located at one of the multiple pre-provided slots on the bolt in accordance with the height of the gap / shelf to be achieved between two barrier sheets.
In the prior art, stacking of enclosures also is avoided as the 3 side extrusions carry fourth side covers which normally just gets snapped onto 3 sided extrusions and do not allow any kind of sealing for achieving IP65 protection. This particular limitation is taken care of in this invention by having slots (34) machined onto base of 3 sided extrusion which allows accommodation of 'O' shaped rubber gaskets (36) during stacking of such extrusions one above the other with raised section on other side of 3 sided extrusion's entry into this groove and then clamping the stacked extrusions with series of bolting carried onto flanges of extrusion. Another advantage of such assembly is compartmentalized IP65 protection, which means IP65 protection failure effect reduction of almost 80 % for entire relay system which is very much essential from MTBF based electronic sub assemblies.

Apart from IP65 protection, the stacked construction also offers RFI/EMI Shielding between each PCB sub-assembly (gap) with each extrusions base metallic wall falling between each PCB.
The same design can be adopted for other enclosures needing compartmentalized IP 65 protection and MEI/RFI shielding with enclosure walls.
With this invention, since the EMI/RFI shielding is achieved by enclosure walls itself, servicing electronic sub assemblies is easier. Since extrusion tool cost is saved, the modular enclosure solution is relatively less expensive.
The front face extruded sheet (20) and the back face extruded sheet (22) fit onto the remainder of the bolted housing with barriers (12) and PCBs (42) to completely seal the housing,
Due to this invention, the following advantages can be cited:
1. No special extruded section is required to be developed.
2. Improved IP protection from MTBF based electronic sub-assemblies.
3. Improved EMI/RFI SHIELDING between electronic sub assemblies which are part of main relay.

We claim,
1. A modular enclosure for holding a plurality of Printed Circuit Boards (PCB), said modular enclosure being adapted to provide EMI / RF shielding and IP protection, said enclosure comprising:
a. housing with extruded barrier sheets, each barrier sheet running along
the length and width of said housing, said barrier sheet being
provisioned at various intervals along the height of said housing to
define gap shelves between two consecutive barrier sheets, between a
topmost barrier sheet and the housing dorsal surface, and between a
lowermost barrier sheet and the housing ventral surface;
b. two lateral extruded sheets, a top extruded sheet, a bottom extruded
sheet, a front face extruded sheet, a back face extruded sheet adapted
to form a perimeter of said housing; and
c. mating mechanism at each location where the extruded sheets mate to
define said perimeter, said mating mechanism being defined by the
lateral extruded sheets including a top edge with a protruding edge
running along its length and further including a bottom edge with a
protruding edge running along its length, wherein slots are defined at
the lateral flanged ends of said operative horizontal top extruded sheet
and said operative horizontal bottom extruded sheet to receive said
protruding edges of each lateral extruded sheet, thereby locking said
lateral extruded sheets with said top extruded sheet and said bottom
extruded sheet to form a housing, and provisioning a gasket in the
spaced apart gap between said top end of protrusion edge and inner

ventral wall of said slot, wherein the winged portion of the protrusion edge and the winged portion of the top edge extending thereof, mate with each other such that they are in metal to metal contact.
2. An enclosure as claimed in claim 1 wherein, said gasket is a rubber gasket.
3. An enclosure as claimed in claim 1 wherein, gasket is an O-ring
4. An enclosure as claimed in claim 1 wherein, said housing includes slots along the inner lateral walls of the lateral extruded sheets in order to receive PCBs.
5. An enclosure as claimed in claim 1 wherein, said housing includes a plurality of bolts through the flanges located at the lateral ends, beyond the slots of the top extruded sheet and bottom extruded sheet.