Note: Descriptions are shown in the official language in which they were submitted.
CA 02571632 2011-10-24
MECHANIZED UNIT FOR PROTECTIVELY ENCASING A UTILITY IN A TRENCH
WITH PROCESSED EXCAVATED TRENCH MATERIAL
BACKGROUND OF THE INVENTION
Mechanized units are known that are moved through a trench in the
ground for the purpose of laying a continuous length or connected lengths of a
utility or
utilities, such as conduits, pipes, cables, etc. or combinations thereof. The
mechanized
unit is primarily intended to place in the trench flexible utilities such as
electrical and
communication and data cables or rigid pipes for water, sewer, and/or gas, or
any
combination thereof, and then encase the one or more utilities with protective
material.
The mechanized unit may be propelled through the trench by being connected
directly
to the device that excavates the trench or by any other mechanical moving
device, such
as a tractor or other vehicle.
In one type of application, the flexible utility or utilities pass down
through the unit onto the bottom of the trench by means of a guide device that
maintains
a desired spatial relationship between utilities in applications in which more
than one
utility is laid in the trench. As the utility or utilities pass through and/or
exit the guide
device, protective material, which has been deposited in the upper portion of
the
mechanized unit, gravitates in a generally vertical direction through the
mechanized unit,
onto and around the utility or utilities being installed. This type of
installation has a
disadvantage in that the material to be used for the encasement must be
specially
obtained, usually by purchasing, from a suitable processing facility, such as
a
gravel/sand pit or stone quarry. Alternatively the encasement material must be
processed on site using portable screening equipment. The purchasing, hauling
and handling or processing and handling of this protective material can add
considerable time and costs to the installation.
U.S. patent 6,981,342, which is assigned to the assignee of the
subject application, describes a mechanized unit that overcomes the forgoing
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disadvantages in an application that uses excavated trench material and that
protects the utility or utilities in a trench in a manner that is efficient
and cost
effective.
In accordance with the invention of the aforesaid patent, a mechanized
unit is provided that places a continuous length or connected lengths of a
utility or
utilities at a predetermined spatial relationship with each other near the
bottom of an
excavated trench. As the mechanized unit moves along the trench, it sweeps the
excavated material that has been placed along the one or both sides of the
trench back
into the trench onto a screening member. The screening member is constructed
with
vertically separate layers of screening material with the screen layers from
top to
bottom having progressively smaller openings. The screening member is mounted
to
the unit with a downward slope from the front to the back in the direction of
unit
movement. As the unit moves, layers of the excavated material of increasing
particle
size are deposited over the utility or utilities one layer above the other.
The layer of
smallest particles directly encase the utility or utilities rather than larger
size particles.
This protects the utility or utilities from stresses or direct physical damage
that would be
caused by large excavated soil or rock particles. The successive upper layer
or layers
further protect the utility. The mechanized unit of the invention accomplishes
this in
one continuous operation together with the laying of the one or more
utilities.
The mechanized unit of the patent is provided with vertical side walls
that hold back the sides of the trench. This prevents collapse of the trench
walls and
also prevents any material from falling into the trench which could damage the
utility or
utilities being installed prior to their encasement by the protective screened
material.
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BRIEF DESCRIPTION OF THE INVENTION
According to the present invention, there is provided a movable unit for
screening excavated material to protectively cover or encase one or more
utilities in
an excavated trench, comprising:
a screening member mounted to the unit and located within the trench above
the one or more utilities in the trench, said screening member having a
plurality of
sections of openings of progressively increasing size relative to the front of
the unit;
a plow for sweeping excavated material lying along at least one side of the
trench onto said screening member, wherein the excavated material swept onto
said screening member passes through the sections of openings of progressively
increasing size to deposit layers of particles of the excavated material of
progressively increasing size onto the utility or utilities installed in the
trench as the
unit moves; and
a guide for placing a length of said one or more utilities into the trench
onto
which the screened material is deposited in the trench as the unit moves.
Preferably, in accordance with the invention, a mechanized unit of the
foregoing type is provided with a simplified screening member that is used to
deposit layers of the excavated material of increasing particle size onto the
one or
more utilities in an excavated trench. The screening member of the invention
has
only a single screen layer with sections of openings of different sizes. That
is, the
screening member extends in a downward sloping direction from the direction of
travel of the unit and the screening member has two or more sections of
openings.
The openings of each section are of substantially the same size and the
openings
of the respective sections progressively increase in size from the front
(higher) end
of the screening member to the rear (lower). Thus, as the excavated material
is
swept from the trench wall onto the screening member, the smaller size
particules
will pass through the smaller size openings first and form a layer that
encases the
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,
one or more utilities, this being followed by a successive layer or layers of
fill
material particles of larger size one on top of the other that pass through
the large
size openings of the respective sections. In a preferred embodiment, a shaker
shakes the screening member.
According to the present invention, there is also provided a movable unit for
screening excavated material to protectively cover or encase one or more
utilities in
an excavated trench, comprising a screening member mounted to the movable unit
and having at least one screen with a plurality of openings sized to permit a
portion
of the excavated material to pass through the openings of the at least one
screen
and deposit onto the utility or utilities installed in the trench as the unit
moves, and a
guide for placing a length of at least one utility into the trench and onto
which the
screened material is deposited as the screening member advances with the
movable unit.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and advantages of this invention will become more apparent
by referring to the following description of operation and referring to the
accompanying drawings, in which:
FIG.1 is a side elevational view in cross-section of the mechanized unit;
FIG.2 is a top view; and
FIG.3 is a orthographical view of the screening member.
DETAILED DESCRIPTION OF THE INVENTION
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Referring to the drawings, the mechanized unit 1 of the invention is
pulled (from right to left as shown in FIG. 1) through a trench 2 by a
conventional
trencher unit 3, illustratively of the wheel type, which excavates the trench.
Such
trencher units 3 dig a trench of predetermined depth and width as it moves
along the
ground. Any other suitable mechanism can be used to excavate the trench and
the
trench also can be hand dug. As the trencher 3 moves it deposits the material
7 that has
been excavated along one or both sides of the top 1 l of the trench 2.
The mechanized unit 1 has a frame to which is mounted a pair of vertical
side walls 30 formed by metal plates that are spaced apart by a distance
generally
corresponding to the space between the trench walls. As the mechanized unit 1
moves
forward, the utility or utilities 4 being installed pass down from a supply
source (not
shown) through the mechanized unit 1 and into the trench 2. The supply source
for the
one or more utilities 4 can be, for example, one or more reels of cable that
are carried by
the unit 1 or by a vehicle moving in parallel with unit 1 along the trench 2,
or pieces of
pipe that are laid down and are joined together. The one or more utilities 4
are
positioned near the bottom of the trench 2, by means of a guide device 6 which
can be
formed of a plurality of rollers or chutes, as appropriate. If more than one
utility is
being laid in the trench, the guide device 6 is preferably configured to
maintain a
desired spatial relationship between the one or more utilities. The unit side
walls 30
prevent the trench from collapsing and protect the utility or utilities as
they are laid in
the trench.
A plow 8 is mounted to each side of the frame of the mechanized unit I
at an angle, for example, about 45 . If the excavated material is placed on
only one side
of the trench, then only one plow is needed. The plows 8 are above the trench
top 11
and contact the excavated material 7 deposited along the one or both sides of
the top 11
of trench 2. As the mechanized unit is moved forward, the plows 8 sweep the
material
7 back into the trench 2 onto the top of a screening member 10, described
below,
mounted to the frame of the mechanized unit 1. As shown in FIG. 2, the ends of
the
plows 8 are stabilized by chains 8a or rigid struts connected to the frame of
the unit.
The height of plows 8 is raised and lowered, preferably by a hydraulic device
9, or by
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any other mechanical means, for example a threaded screw arrangement, so that
the
appropriate amount of excavated material 7 is plowed back into the trench 2.
Referring to Fig. 3, the screening member 10 has a frame having an end
19 pivotally connected to the frame of mechanized unit 1 and extends below the
top 11
of the trench 2. The screening member 10 fits between the mechanized unit side
walls
30 and slopes in a downward direction away from the rear of the unit 1. The
screening
member 10 has one layer and a plurality of screen sections of different size,
or mesh
size. Each plurality of openings of a section is of substantially the same
size, but the
sizes of the openings progressively increase from section to section toward
the rear of
the screening member. As seen in Fig. 3, the screening member 10 single layer
illustratively has four sections 10a, 10b, 10c and 10d with progressively
larger openings
(mesh size) front to rear. That is, the openings of each of the sections is of
the same
size. The openings of section 10b are larger than those of section 10a, the
openings of
section 10c are larger than those of 10b, and the openings of section 10d are
larger than
those of section 10c. While four sections 10a-10d are shown, there can be
fewer, but at
least two, or more than four.
As the mechanized unit 1 moves forward in the trench the smaller
particles that pass through the smaller openings of the section 10a openings
toward the
front of the screening member 10 gravitate to encase and cover the utility or
utilities 4 at
the bottom of the trench 2 prior to the larger particles passing through the
larger
openings of sections 10b, 10c and 10d toward the rear of the screening member
10
gravitating onto the smaller particles previously deposited. Particles that
are larger than
the openings of all of the sections slide off the lower end of the screening
member into
the trench to form the top layer of the encasement. This covers the utility or
utilities 4
with protective material from bottom to top with particle sizes that are
progressively
smaller to larger. While the screening member 10 is shown with four sections
of
openings of different sizes, there can be two or more.
In a typical embodiment, the screening member 10 has a downward
slope of about 18 , a width of 12 inches, and a length of 8 feet. The openings
of section
10a are 3/8", those of section 10d are 1", and those of sections 10b and 10c
of
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increasing size from between 3/8" to 1". All of the foregoing dimensions are
by way of
illustration only and can be varied to suit a particular application.
A shaker 14 formed by a hydraulic motor 15 or any other mechanical
means is mounted to the unit 1 framework. The motor 15 turns a crankshaft 16
that is
connected to the screening member 10 frame by a connecting rod 17. The shaker
14 is
operated at a desired rate and preferably has a movement that moves the
screening
member 10 by a desired distance forward and back and up-and-down. Any suitable
conventional type of shaking or vibrating device can be utilized.
As the excavated material passes vertically through the openings of
sections 10a, 10b, 10c and 10d of the screening member 10, it is separated by
particle
size. In the embodiment shown, as the mechanized unit 1 moves forward, the
screening
member causes four layers of encasing material of progressively larger
particle size to
be laid over the one or more utilities 4. The first layer is the smallest
particle size
material 18 that passes through the openings of the screening member section
10a. The
smallest size particles pass through the first screen section 10a to directly
contact and
cover the utility or utilities 4 that have been placed near the bottom of the
trench 2. If
the one or more utilities are slightly raised from the trench floor, the
smaller size
particles will flow below them and form a bed. The second, third and fourth
layers are
the particles of material that have passed through the progressively larger
openings of
the successive sections 10b, 10c and 10d.
The large particles that do not pass through any of the openings of
sections 10a-10d gravitate down along the upper surface of the screen and are
shaken
down and to the rear of that screen until they fall off of the back end of the
screen and
gravitate onto the already deposited layers of material. Even though the size
of these
largest particles falling off the end of the screen may be relatively large,
they do not
damage the one or more utilities laid in the trench since these are already
covered by
four layers of material of smaller particle size. Also, the force of the large
particles
sliding off the screen is relatively small as compared to a direct vertical
drop of such
large size particles. Accordingly, as seen, the screening member 10 functions
to cover
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the utility or utilities with layers of protective materials of successively
increasing
particle size.
While the illustrative embodiment of screening member 10 has only one
layer, five layers of particles will be provided, these being the layer of
particles from
each of the four screening sections 10a, 10b, 10c and 10d, and the particles
that fall off
the end of the screen.
A guide device 20 preferably is attached at the rear of the mechanized
unit 1 to place a warning ribbon 21 in the trench above the installed utility
or utilities.
The roll of warning ribbon 22 is supported by a warning ribbon roll support 23
attached
to the unit 1 framework.
Specific features of the invention are shown in one or more of the
drawings for convenience only, as each feature may be combined with other
features in
accordance with the invention.
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