Note: Descriptions are shown in the official language in which they were submitted.
-1~ Case 2748
HIGH INTENSITY BALL~ST ASSEMBLY
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The present invention relates to a ballast housing
assembly for use with gaseous discharge lamps, and partic-
ularly it relates to a remote weatherproof ballast housing
assembly.
It is well kno~n in the art o~ weatherproo~ ballast
housin~ construction that the electrical components of the
ballast circuit show improved reliability and longevity when
protected from adverse en~ironmental effects.
One approach employed in the construction of weather-
proof ballast housing has been to use a potting compound, such
as an epoxy resin or asphalt~ to position an seal the com-
ponents within the ballast housing. There are, however,
multiple disadvan-tages which may arise through the use of
potting compounds. For example, water has been kno~n to
become trapped within the voids o~ hydroscopic potting
compounds such as asphalt. O~er a period of time a corrosive
solution may be produced through interaction o~ the water with
the potting compound and where such a solution has access
to the electrical components there exists the possibility of
premature ballast circuit ~ailure. Another disadvantage which
may be encountered when pott~ng compounds such as cured
epoxy-sand blends are utilized, is the potential explosive
hazard that ~rises ~hen the ballast circuit is operated at
abnormally high temperatures that may occur during ballast
failure. Under these conditions the epoxy compound breaks
down, generatin~ methane gas which may subsequently ignite
and, in the enclosed housing~ explode. Still another
disadvantage associated with potting compounds is their
- tendency to restrict capacitor expansion during a capacitor
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Case 2748
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fail condition, thus precluding a timely capacitor shut down.
One prior art weatherproof ballast housing assembly
which is not subject to the above mentioned disadvantages is
disclosed in Canadian Patent No. 923,607 which issued on
March 27, 1973 to Freegard et al. The Freegard patent dis-
closes an unpotted weatherproof ballast housing assembly
consisting of a single deep drawn or spun aluminum housing
member supported on an elaborate structural base. The housing
member itself performs no support function. A cast base is
provided which acts both as a heat sink and a support member
to provide the necessary strength in the ballast housing
assembly. The need for such an elaborate base in the Freegard
ballast housing remains a disadvantage in the cost of manu-
facturing such a housing.
Canadian Patent No. 906,631 issued to Osteen et al
on August 1, 1972, discloses an unpotted weatherproof ballast
housing assembly having two compartments. The housing members
of Osteen's assembly are complementary castings wherein one
of the castings provides a ridge portion along its upper face
which fits with a corresponding trough in the lower face of
the other casting so as to affect a weatherproof seal along
the abutting faces in the assembly. The housing members
fu~-ther provide the structural support for the electrical
components and for a luminaire which is designed to depend
from the ballast housing. The structural requirements placed
on the housing members give rise to a design from which heat
cannot be readily dissipated and so, special consideration
is given to the thermal isolation of the capacitor from the
heat produced by both the transformer and the depending
luminaire. An insulating multi-layered composite plate
structure is provided to affect the thermal isolation of
the capacitor. The plate is clamped between the abuting
faces of the housing members and effectively divides the
chamber into two compartments wherein the respective
electronic components are located. The cast housing
members and the plate structure contribute significantly
to the increased cost of manufacturing the ballast housing
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Case 2748
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assembly.
It is therefore a feature of the present invention
to provide a weatherproof ballast housing assembly which
is ineXPensive to manufacture and easily maintained.
~riefly, the present invention pro~ides a weather-
proof ballast hoUSing assembly suitable foruse with a gaseous
discharge lamp. The ballast housing assembly comprises two
housing members, one having an offset flange portion and the
other having an open ended rim portion. The flange portion and
the rim portion of the respective housing members co-act in
conjunction with suitable securing means over a co-acting region
to provide a weatherproof chamber. The co-acting housing
members and the securing means further serve to secure in
mutually fixed relation with the housing members a plate
member of a sub-assembly. The sub-assembly further com-
prises a transformer and a capacitor mounted on opposing
surfaces of the Plate member. The plate member divides the
chamber into two compar*ments in which respectively reside
the transformer and the capacitor. The particular arrangements
of the housing members and the sub-assembly in relation to the
securing means is suchthat the ballast housing assembly is
weatherproof; inexpensive to manufacture and easily main-
tained.
Therefore, ir accordance with a broad aspect of the
present invention there is provided a ballast housing assembly
suitable for use with a gaseous discharge lamp. The ballast
housing assembly comprises first and second housing members
defining a chamber having an axis. The first housing member
has an offset flange portion which comprises a flrst segment
extending parallel to the chambers axis. A second segment
of the offset flange portion serves to space the first segment
from the first housing member. The second housing member
has an open ended rim portion. The first segment of the
flange portion of the first housing member co-acts with a
predetermined length of the rim portion of the second housing
member to align the rim portion and the first segment in
mutually aligned relation, thereby defining a weatherproof
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Case 2748
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seal over the co-acting regionO The housing member having
the largest cross-sectional dimension as measured across
the co-acting region is oriented uppermost along the axis
of the final assembly. The plate member is a part of a
sub-assembly which further comprises a transformer and a
capacitor mounted on opposing surfaces of the plate member.
The plate member overlays the rim face of the lower housing
member and divides the chamber into two compartments. Also
included in the ballast housing assembly is removable
securing means for securing the first and second housing members
in mutually fixed relation with the plate member.
For a better understanding of the nature and features
of the present invention, reference may be made to the
diagrammatic representations of selected embodiments for
lS the ballast housing assembly as depicted in the accompanying
drawings.
Figure l is a partially cut away, three dimensional
view of the preferred embodiment of the present invention.
Figure 2 is an enlarged view of a portion of the
co-acting region of the ballast housing assembly shown in
Figure l.
Figures 3, 4 and 5 are views of portions of the
co-acting regions ~or various alternate embodiments of the
ballast housing assembly of the present invention.
Referring now to Figures 1 and 2, the preferred
embodiment of the present invention is shown as a remote,
weatherproof ballast housing assembly which is suitable for
use with a gaseous discharge lamp. The ballast housing
assembly comprises an upper housing member 10 having an
open ended cylindrical rim portion 12 and a lower housing
member 14 having a radially offset flange portion 16. The
flange portion 16 includes a radially planar segment 18
that extends inwardly towards the longitudinal axis 20 of
the chamber 22. The flange portion 16 further includes a
cylindrical segment 24 that extends upwardly away from the
planar segment 18 to terminate in a circular rim face 26.
A sub-assembly 30 comprises a plate member 28 that overlays the
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Case 2748
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circular rim face 26 of the lower housing member 14 so as to
divide the chamber 22 into upper and lower compartments 44
and 46 respectively. The plate member 28 has a depen~ing
skirt portion 32 which extends throughout a co-acting
region 34 (see figure 2). The co-acting region 34 is
defined as that region lying between and including the
cylindrical rim portion 12 of the upper housing member 10
and the cylindrical segment 24 of the flange portion 16.
Suitable securing means such as screws 36 are disposed about
the co-acting region 34 to secure the upper and lower
housing members 10 and 14 respectively, in mutually fixed
relation with the plate member 28. Also shown/ mounted on
the opposing surfaces of the plate member 28 are a
transformer 38, a capacitor 40 and an ignitor circuit 48,
each of which form a part of the sub-assembly 30. It should
be understood that the principal heat transfer path from
transformer 38 is via radiation through the air space of
upper compartment 44 to the upper housing member 10. Heat
is dissipated from the upper housing member exterior surfaces
through convection and radiation to the environment. Also,
transformer 38 is shown located in the uppermost compartment
44 thereby further enhancing the dissipation of heat
generated through trans~ormer operation. A similar heat
transfer path is provided for heat generated by the capacitor
40 and the ignitor circuit 48 through the lower compartment 46
to the lower housing member 14. While plate member 28 may
function to some degree as a heat sink for the components
mounted thereon, the main thermodynamic function is to
present a heat barrier between the transformer 38 and ~he
capacitor 40/ignitor circuit 48. It will be understood that a
wire path,appropriate to ballast circuit applications, will
extend to the various electrical components and will communi-
cate exteriorly of the ballast housing assembly as re~uired.
Figure 1 shows such a path 51 extending through the base
of the lower housing member 14 by way of a strain relief devide
56. Clearly a similar path must also exist between the upper
and lower compartments, 44 and 46 respectively.
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Case 2748
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Figure 1 shows such a path 52, in cross section. Open path
52 extends through plate member 28 and further includes a
through plate member 28 and further includes a drip protrusion
53. The drip protrusion allows condensation produced
within upper compartment 44 to drip to the floor of lower
housing member 14, but prevents the droplets from migrating
along the lower surface of plate member 28 and contacting the
electrical components mounted thereon. It is no~ed that lead
54 is formed with a loop 55 as shown in Figure 1. This
prevents condensation from travelling along the exterior of
the wire and contacting the electrical components to which
the wire is attached. Instead, the condensation gravitates
to the lowest point of loop 55 and, when a large enough droplet
is formed, falls to the floor of lower housing member 14. It
will be understood that, while for the sake of clarity only
one lead is shown, the number of leads in any particular ballast
arrangement will be commensurate with the number of leads
required for the operation of the ballast circuit. Drainage
of the lower housing member 14 is provided through the floor
of the lower housing member via a strain relief device 56.
Water is permitted to escape through gaps in and around the
strain relief device. A mounting bracket 50 is provided ~or
mounting the ballast housing assembly on a suitable support.
Referring now to Figure 3 there is shown a portion
of the co-acting region for an alternate embodiment of the
ballast housing assembly of the present invention. Figure 3
illustrates, inter alia, an upper housing member 310 having
a radially offset flange portion 316, and a lower housing
member 314 having an open ended cylindrical rim portion 312
which terminates in a circular rim face 326. The flange
portion 316 includes a radially planar segment 318 w~ich
extends outwardly from the longitudinal axis of the chamber.
The flan~e portion 316 further includes a cylindrical segment
324 which extends downwardly from the planar segment 318.
A plate member 328 o~erlays the circular rim face 326 of the
lower housing member 314. The plate member 328 includes a
depending skirt portion 332 which extends throughout a
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Case 2748
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a co-acting region 334. The co-acting region 334 is defined as
that region lying between and including the rim portion 312
and the cylindrical segment 324. Securing means such as
screws 36 are disposed about the co-acting region 334 to
secure the upper and lower housing members, 310 and 314
respectively, in mutually fixed relation with plate member
328. The plate members described in connection with
Figures 1, 2 and 3 all include a depending skirt portion.
The skirt portion in each case provides extra strength to
the ballast housing assembly as a whole, increases the
load bearing capacity of the plate member and improves the
weatherproof seal throughout the co-acting region.
Referring now to Figure 4, there is shown a portion
of the co-acting region for an alternate embodiment of the
present invention. The~plate member of this embodiment does
not include a depending skirt portion. Upper and lower housing
members 410 and 414 respectiveIy, are identical to the
coxresponding members described in relation to Figure 3. A
yasket 460 is disposed throughout the co-acting region
434 defined between and including rim portion 412 and cyl-
indrical segment 424. Securing means such as screws 36
are disposed about the co-acting region 434 to secure the
upper and lower housing memb-ers, 410 and 414 respectively,
in mutually fixed relation with plate member 428. The
arrangement of elements in this embodiment permit a further
cost reduction in manufacturing although some structural
strength is sacrificed. Accordingly, this arrangement is
best suited for smaller ballast assemblies. The gasket
material maintains the highly weatherproof seal character-
istics of the ballast housing assemblies described in
Figuresl, 2 and 3 .
Referring now to Figure 5, there is shown a portion
of the co-acting region for an alternate embodiment wherein,
again, the plate member does not include a depending skirt
portion nor is there a yasket provided in the co-acting
region. Upper and lower housing members~ 510 and 514
respectively, are similar to those described in relation
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Case 2748
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to Figures 3 and 4. The embodiment of ballast housing
assembly of Figure 5 is best suited to smaller ballast
assemblies for use under climatic conditions which are
somewhat less rigorous than those under which the preceding
embodiments are best suited for use.
The foregoing has been a description of various
embodiments of the present invention.
It should be understood, however, that the present
invention is not necessarily restricted to a ballast housing
assembly having a cylindrical configuration. For example,
a ballast housing assembly having a rectangular shape may
be alternately employed to reflect, through the teachings
of the instant disclosure, the substance and advantages
of the present invention~
Furthermore, any suitable drainage means may be a
employed to drain the lower housing member.
It will also be understood that, while the instant
disclosure deals with a weatherproof ballast housing assembly,
a few minor alterations such as the exclusion of drain holes
and the appropriate application of gasket materials or
sealants will render the ballast housing assembly of the
instant invention dust tight or water right, depending on
the nature and extent of the alterations made thereto.
Further alternate embodiments will be readily
apparent to a man skilled in the art in light of the instant
disclosure. ~ccordingly, the present invention should only
be limited to that which is claimed in the accompanying
claims.
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