Note: Descriptions are shown in the official language in which they were submitted.
- L -
I'he present invention Kelates to a device Eor securing
a manhole cover to a manhole opening and for relieving excess
fluid pressllre which occur within the manhole.
5 BACKGROUND OF T~E INVENTIO~
The present invention is primarily concerned with the
problem of and the consequences associated ~ith "popping" of
sewer lids by excess fluid or pressure within a drainage system,
a situation which is not infrequent in areas which experience
extreme weather conditions. One serious consequence is that
removal of the cover may be sufficientl~ forcible as to cause
injuries to persons or damage to property in the vicinity of the
manhole. Another conse~uence is that the cover may be carried
away with the stream which issues from the manhole opening~
thereby requiring retrieval and replacement of -the cover. More
importantly, this conditions results in an open manhole which,
once the excess pressure has been relieved, may present an
invitation to children or, as has been known to happen, may
actually suck a person into the manhole as water retreats back
into the manhole.
Canadian Patent No. 303 91~ granted on September 16,
1930 proposes a solution to -the aforementioned problem and, in
particular, a manhole cover having a dependin~ skirt having slots
extending upwardly from the bottom of the skirt in a tortuous
fashion and adapted to receive pins extending inwardly from the
manhole opening. Thus r should the water level within the manhole
rise up against underside of the cover, the pins and slots
cooperate to permit the cover and skirt to rise until the pins
reach a horizontal portion of the slots at which point the pins
and slots cooperate to hold the cover in an open position.
Accordingly, excess water is permitted to escape through openings
in the skirt~ This arrangernent does not entirely illeviate the
afore-di6cussed problems. Firstly, it is conceivable that the
pins could be freed from the slots, and the cover thus dislod~ed,
if the ~7ater pressure is sufficiently high and applied abruptly,
such as by an explosion within the manhole. Secondly, since the
~'
3~ D~s
-- 2 --
device is designed to hold the cover in an open position~ it is
still necessary to manually close the cover. Thirdly, the
complex slot design is relatively difficult and, there~ore,
expensive to manufacture.
SUMMARY O_ THE INV~NTION
The present invention seel~s to provide a device which
secures a manhole cover to a manhole in such a way that the cover
is permitted to open under excess pressure conditions and thereby
relieve excess pressure and return automaticall~ to its closed
position once the pressure returns to its normal level~ In
addition, the present invention seeks to provide a light weight
arrangement which is readilly and inexpensively manufactured.
In general, the present invention provides a device for
use with a manhole cover for releasing excess fluid pressure
within a manhole or the like, the device comprising a tubular
member having a tubular wall, fluid inlet means at one end
thereof, fluid outlet means in the wall, means at the other end
thereof for securing the member to the cover, and means for
securing the member to the manhole adjacent a manhole opening for
longitudinal movement of the member between a closed position
whereat the cGver closes the opening and an open position whereat
the cover is displaced fro~ the opening permitting fluid flow
from the manhole into the member via the inlet means and
outwardly of the member and the manhole opening via the outlet
means. ~'he member securing means permits movement of the member
rom the closed position at a predetermined fluid pressure within
the manhole and permits the member to return to the closed
position when the fluid pressure drops below the predetermined
pressure.
BKIEF DESCRIPTION OF TEIE DRAWINGS
-
These and oth~r features of the invention will become
more apparent from the following description in which reference
is made to the appended drawings, wherein:
FIGURE 1 is a longitudinal cross-sectional view of a
manhole opening illustrating a device intended for new manhole
construction constructed in accordance with ~he present invention
operatively securing a manhole cover to a manhole in open and
closed positions;
FIGURE 2 is a partially broken, partial cross-sec-tional
view illustrating a means for connecting a manhole cover to the
device of the present invention;
FIGURE 3 is a view of the underside of a manhole cover;
FIGURE A is a broken cross-sectional view illustrating
an arrangement for connecting the device of the present invention
to a manhole opening in a new manhole; and
FIGURE 5 is a broken cross-sectional view of an
arrangement for connecting the device of the present invention in
an existing manhole.
DESCRIPTION OF A PR ElERRED EMBODIMENT
FIGURE 1 i.llustrates a typical manhole 10 compri.sed of
a tubular member 12 formed of masonary material, such as
concrete, a concrete support ring 13 seated upon the upper end o-f
member 12 and a metal. collar 14 seated upon ring 13 and set in
asphalt 16 or the like forming a road surface 18. In the
illustrated structure, the collar is unitary and comprised of an
annular base portion 20, a conicall tubular neck portion 22 which
extends from the inner edge of the base, a plurality of radially
outwardly exkending reinforcing ribs 24 and a radially inwardly
extending annular flange 25 at the upper end of the neck portion.
4~$~
Flange 25 is formed with an upwardly Eacing seat 28 for the cover
30 and, with neck portion 22, defines a manhole opening or
hatchway 26.
Cover 30 is comprised of a disc-shaped portion 32 from
which a cylindrical skirt 34 concentrically depends. Disc 32 and
skirt 34 together define an annular shoulder 36 which is arranged
to sit upon seat 28 of the collar while the skirt is arranged to
be telescopingly received within opening 26 as shown. Cross-ribs
38 (see FIGURE 3) extend diametrically across the underside of
the disc between the inner cylindrical surface 41 of the skirt.
Each end of the cross-ribs is formed, adjacent surface 41, with a
rectangu]ar aperture 40 whose upper edge 42 is spaced from disc
32 50 as to define a key 44, the purpose of which will become
clear hereinbelow.
In accordance with the present invention there is
provided a device, generally designated by reference numeral 50,
for securing the cover to the manhole in such a way as to permit
excess water within the manhole to flow outwardly of the
hatchway. The device is generally comprised oE an inner tubular
member or sleeve 52, having a tubular wall 54, which is open at
its lower end 56 to define a fluid inlet means. Wall 54 is
perforated so as to define a fluid outlet means. Cover securing
means 58, in the orm of L-shaped fingers, are provided at the
upper end of sleeve 52 for detachably securing the sleeve to the
cover. Sleeve securing means 60 are provided for securing the
sleeve to the manhole adjacent a manhole opening while allowing
longitudinal movement of the sleeve between a closed position,
shown in solid lines in FIGURE 1, whereat the cover closes the
opening and an open position, shown in dotted and dashed lines
whereat the cover i5 removed from the opening permitting fluid
flow from the manhole into the sleeve via the inlet means and
outwardly of the sleeve and the manhole opening via the outlet
means. As explained more fully hereinbelow, securing means 60
permits the sleeve to return to the closed position when the
fluid pressure and level within the manhole return to normal.
~q.l~
As best shown in FLGUE~E 2, the outer diameter of sleeve
52 is substantially the same as that of skirt 34 of the cover so
that the upper end of the sleeve abuttingly engages -the lower
edge of the skirt when the two components are secured together in
the manner which will now be explained. The cover securiny means
58 comprises four equally spaced L-shaped fingers 70. Each
finger has one arm 72 which is secured to the inside surface 71
of the sleeve and projects longitudinally beyond the upper end of
the sleeve and another arm 74 which e~tends generally
circumferentially of and in spaced relation to the upper end of
the sleeveO Arm 74 is arranged to be received within an aperture
40 and is dimensioned so as to be capable of limited axial
movement within the aperture while preventing axial separation of
the cover and sleeve. The edge of arm 74 remote from sleeve 52
is formed with a notch 76 dimensioned to receive a key 44. Thus,
when engaged, the notch and key are operable to prevent rotation
of the cover with respect to the sleeve.
To assemble the cover on the sleeve, the fingers are
inserted in to the spaces between cross-ribs 38 of the cover and
arms 74 are aligned with and inserted into the apertures by
rotation of the cover relative to the sleeve until edge 73 of
arms 72 abut ribs 38, at which point notches 76 and keys 44 are
axially alignedO The cover is then lowered onto the upper edge
of the sleeve which places the keys within the notches. The
reverse procedure is followed in order to remove -the cover. It
will be understood that the cover can be readilly removed from
inside the manhole simply by lifting the cover slightly, rotating
the cover to disengage the fingers Erom the apertures and then
pushing the cover off.
As previously indicated, sleeve 52 is perforated to
define a fluid outlet means. More specifically, the sleeve is
formed with a multiplicity of small diameter apertures 80 which
not only serve as a fluid oulet means but also serve to minimize
the weight of the device. The sleeve may additionally be
provided with a number, such as four for example, equally spaced,
~ '3~3~
longitudinally extending generally rectangular openings 82 to
reduce resistance to fluid flow and to receive the heads of
mounting bolts or nuts ~see FIGURE 5) used in adapting the device
to existing manholes.
A preferred arrangement 60 of securing and guiding
sleeve 52 in a new manhole construction will now be described
with reference to FIGURES 1 and 4 of the drawings. This
arrangement is comprised of an outer tubular member or sleeve 90
which is open at both ends and which is dimensioned to
telescopingly receive sleeve 52. Sleeve 90 is provided with a
number of arms 92, each formed with an upturned lip 94 at its
free end, which are secured to and extend radially outwardly from
the mid portion of ~he sleeve. The underside 96 of arms 92 are
adapted to sit upon the concrete support ring 13 of manhole 10
while the upperside 100 of the arms form a seat for base 20 of
collar 14. Lips 94 serve to concentrically align collar 14 and
sleeve 90. A rib 98 haviny an upwardly inclined undersurface 99
is provided on the underside of each arm 92 ad~acent sleeve 90
for guiding the sleeve into position during initial installation.
Sleeve 90 may be perorated if desired to minimize the weight of
the assembly.
Retaining means 102 in the form of pins, each of which
may comprise a ~olt 104 and elongated nut 106, are secured to and
extend radially inwardly from the upper end of sleeve 90 as
shown7 Each retaining means is arranged to be loosely received
within an associated elongated, longitudinally extending slot 108
in sleeve 52. Upper and lower ends 110 and 112 of slots 108
are operable when engaged with nuts 106 to define the fully
opened and fully closed positions of the inner sleeve. Thus, it
will be seen that sleeve 52 is free to move axially between
limits defined by the ends of slots 108 while being securely
tethered to the manhole.
The sleeves may be formed of any suitable material
including steel, plastic, aluminum and the like. It has been
~ound that an arrangement wherein sleeves 52 and 90 are cold
rolled from 11 gauge 1/8 inch perforated steel plate to provicle
sleeve 52 with an inside diameter of 20 inches and sleeve 90 with
an outside diameter of ~0-9/16 inches, each with a length of 12
inches and a slot 108 length of 10 inches performs quite
adequately for the purposes of the present invention.
Under normal circumstances, the device assumes the
position illustrated in solid lines in FIGURE 1. Should the
water level within the manhole rise to and beyond road level,
water pressure will force the cover and sleeve 52 to move
upwardly thus allowing water to flow outwardly of the manhole
through the apertures in sleeve 52. When the water level returns
to normal, the cover and sleeve automakically return to the
closed position. It will be seen that this arrangement overcomes
the inconvenience and expense of retrieving dislodged manhole
covers following a severve storm, but, more importantly, keeps
the manhole essentially closed to children, animals and the like.
Above described sleeve fastening means 60 is a
preferred arrangement for use with new manhole installations.
FISURE 5 illustra-tes a sleeve securing arrangement which may be
used to readilly modify an existing manhole installation. Rather
than removing the collar to place arms 92 between the collar and
the support ringr as previously explained, there is provided an
outer sleeve 190 which is formed without the arms but which is
secured to the support ring by means of anchor bolts 192 mounted
in the support ring and nuks 194, as shown. The inner ends oE
the bolts and the inner nuts extending into aforementioned
openings 82 in the inner sleeve and, therefore, do not interEere
with th~ operation of the inner sleeve~
It will be understood thak an alternative mounting
arrangement is to mount retaining means 102 directly in the
concrete ring or elsewhere in the manhole. It will be understood
that various other modifications and alterations can be made to
the above described invention without departing from the spirit
of the appended claims.
