Note: Descriptions are shown in the official language in which they were submitted.
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Drag Reduction Fairing for a Trailer Converter Dolly
Field of the Invention
This invention relates to devices to reduce drag and therefore increase fuel
efficiency with respect to trailers, and in particular, relates to fairings
which are to be used in
5 combination with trailer converter dollies.
Background of the Invention
In recent years, trucking companies have become more conscious of the costs of
fuel consumed by their vehicles, particularly those trucks - which are very
often referred to
as tractors - whose purpose is to tow a trailer or trailers along the roadway,
and especially
10 at high speeds along a highway. While the manufacturers of such trucks
are doing their
best to improve efficiencies by making their truck designs more aerodynamic,
and making
their engines more fuel efficient, the fact remains that significant
aerodynamic losses occur
as a result of trailer design, especially at high speed. The current trailer
designs create drag
on the trailer due to wind resistance as the trailer moves. Even if the engine
and the
15 aerodynamic design of the trucks is improved, there still remains the
problem of reducing
the drag created by the trailer, so as to thereby increase the fuel efficiency
of the towing
truck.
=
Federal and state authorities in the United States and Canada are increasingly
tightening the restrictions as they apply to the trucking industry, requiring
increased
20 efficiency so as to reduce carbon and greenhouse gas emissions from the
trucks. Indeed,
the California Air Resources Board has mandated that trailers must manifest
lower drag
coefficients so as to reduce carbon and greenhouse gas emissions in that
state.
One common approach to reduction of drag by trailers has been to fit or
retrofit the
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trailers with fairings mounted along each side of the trailer, as seen in, for
example, US
Patent No. 7578541.
Another approach has been to provide a central drag reduction plate along at
least
a portion of the trailer length, as described in US patent publication No.
2013/0285411. The
central drag reduction plate can be located adjacent to an additional
transverse fairing
which extends across the trailer, in front of the rear set of wheels. It is
well established that
trailer wheel assemblies are not aerodynamic and can increase the drag on the
trailer when
it is driven.
Other approaches have included the use of a variety of fairing of different
sizes and
shapes located on the underside of the trailer. These are typically located at
or near the
landing gear assemblies, and/or the trailer wheel assemblies.
While these approaches do provide some aerodynamic advantages, and thus some
fuel economy benefits, further improvement in this area is always desirable.
Further, common in the trucking industry is the use of multiple trailers
attached in
series to a single tractor. In this approach, a first additional trailer is
typically attached to the
tractor, or attached to a fifth wheel assembly located at the back of the
tractor. At the back
of the first trailer is trailer hitching assembly, such as an pintle hook, to
which a converter
dolly assembly can be attached. The converter dolly assembly comprises a
support frame
to which a wheel assembly, and an additional fifth wheel assembly is attached,
and also
includes a corresponding hitching assembly, such as an pintle eye at its front
end, which is
adapted to be connected to the trailer pintle hook. A further trailer
(sometimes referred to as
a "pup" trailer) can be attached to the converter dolly, by use of the
additional fifth wheel.
In turn, the second trailer can also include a further pintle hook, or other
hitching
assembly, to which a further converter dolly, and thus trailer, can be fitted.
While use of converter dollies is well established in order to add an
additional trailer
or trailers to a tractor-trailer or truck-trailer configuration, there has
been little attempt to
improve the aerodynamics around the dolly, and its integral wheel assembly.
The present inventors have unexpectedly discovered that placing fairings on
the
dolly, in front of the wheels on each side of the wheel assembly, will reduce
drag on the
tractor-trailer combination, especially at higher speeds. Regardless of the
use of other
fairings fitted to the tractor and/or trailer, the fairings of the present
invention, attached to
the converter dolly, provide additional aerodynamic benefits.
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Description of the Prior Art
Several patents teach the use of underbody trailer fairings, which have some
adjustability as to their fitment to a trailer.
In U.S. Patent No. 5,921,617 patent issued July 13, 1999 to Loewen et al, and
teaches a fairing assembly whicl has longitudinally extending forward and
rearward
sections. The intent is for the rearward section to be moved longitudinally so
as to
adjustably locate its rearward edge in a selected position forward of the
wheel assembly of
the trailer. To accommodate such adjustment, the rearward section is coupled
to and
longitudinally movable with the support frame for the wheel assembly, thereby
maintaining
its longitudinal adjustment relative to the trailer and to the wheel assembly.
A hinge
mechanism permits each section of the fairing to be pivotally displaced
between lowered
and raised positions. The patent states that improved fuel economy may be
achieved while
the trailer is towed at highway speeds over long distances with proper
mounting of the
fairings. The lowered and raised positions of the fairings are intended to
accommodate
situations where the trailer may be moved over ramps or uneven terrain.
U.S. Patent No. 6,644,720 issued November 11, 2003 to Long et al, and teaches
an
adjustable trailer underbody fairing structure, where the fairing includes an
adjustable
fairing panel which extends and collapses as the rear wheel assembly of the
trailer is
moved, so as to present a planar fairing surface at all times. Once again, the
patent speaks
of improving long distance fuel economy for the haulage of trailers by the
fitment of fairings
mounted at each lower longitudinal edge of the trailer. It is important,
according to the
patent, that the fairing can be adjusted quickly and easily to accommodate
repositioning of
the wheel assembly of the trailer, so that the length of the fairing shall be
optimized in each
situation so as to reach maximum fuel economy. Accordingly, the fairing
structure includes
a foldable panel which has a plurality of vertically oriented slats that are
slidably mounted
on a telescoping frame, each of the slats having a fabric mounted thereon. The
intention is
that the adjustable fairing panel shall fold and unfold in the manner of an
accordion, so as
to permit adjustment of the fairing. However, it is important, as well, for
the fabric to be put
into tension in order to maintain reduced fuel efficiency.
U.S. Patent Application Publication 2008/0238139, published October 2, 2008,
relates to an application filed by Cardolle. That application proposes a
somewhat different
approach so as to reduce fuel consumption, particularly for motorized vehicles
when they
are pulling trailers, many of which lack in aerodynamic design. The intent is
to provide a
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structure which gives clearance between the axles of the trailer, and which
allows access to
the underbody of the trailer. This involves the provision of a transverse
fairing which can be
designed to facilitate the forward movement of the trailer by placing the
fairing in front of a
rear wheel assembly so as to divert airflow which is engulfed in the underside
of the trailer
towards the sides of the trailer. Accordingly, a fairing shell is placed in
front of the wheel
assembly and is shaped so as tc divert the air that flows away from the wheel
assembly.
The shell covers substantially the frontal area of the wheel assembly, and may
have side
extensions which extend along the sides of the trailer so as to at least
partially cover the
sides of the wheel set.
U.S. Pat. No. 4,262,953 that issued to McErlane teaches "an airfoil or
deflector
panel for being mounted ahead of the rearmost set of wheels of a vehicle such
as a truck or
tractor-drawn trailer to direct air flow in a manner which reduces the
relatively negative air
pressure normally occurring behind a moving vehicle. The surface of the
deflector which is
presented in the direction of vehicle motion has a bilateral or compound
convex curve."
U.S. Pat. No. 4,640,541 that issued to FitzGerald teaches "an air deflector
for the
rear wheels of vehicles such as trucks and trailers is disclosed. The
deflector consists of a
fairing suspended beneath the truck or trailer body immediately in front of
the rear wheels
and extending completely across the width of the body. The surface of the
fairing is curved
in both a lateral and a vertical direction to deflect impinging air and
entrained water or snow
around or under the wheels.
U.S. Pat. No. 4,938,524 that issued to Straub teaches "a semi-truck trailer
gooseneck assembly comprises a single curved plate extending transversely
between and
beyond the twin parallel longitudinal girders to form a single lower flange.
The curved plate
extends from the assembly supporting the floor over the fifth wheel and
connecting the king
pin to the trailer.
U.S. Pat. No. 6,837,536 that issued to Schwartz teaches "a belly pan, or
membrane
of rigid yet flexible material is of elongated shaped outline to be mounted
along the bottom
of tractor-trailer. An aerodynamic shaped deflector is attached to the frontal
portion of the
landing gear of the trailer and attaches to the belly pan for reducing drag
between the
underside of the trailer and the support beams of the landing gear.
U.S. Pat. No. 6,974,178 that issued to Ortega teaches an apparatus for
reducing the
aerodynamic drag of a wheeled vehicle in a flow stream, the vehicle having a
vehicle body
and a wheel assembly supporting the vehicle body. The apparatus includes a
baffle
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assembly adapted to be positioned upstream of the wheel assembly for
deflecting airflow
away from the wheel assembly so as to reduce the incident pressure on the
wheel
assembly.
U.S. Pat. No. 7,093,889 that issued to Graham teaches a device comprising a
plurality of load bearing struts attached to the bottom of the rectangular
body adjacent its
sides, a plurality of opposing flat sheets attached to the load bearing
struts, and angled
flaps attached to the lower edge Jf the opposing sheets defining an obtuse
angle with the
opposing flat sheets extending inwardly with respect to the sides of the
rectangular body to
a predetermined height above the ground, which, stiffen the opposing flat
sheets, bend to
resist damage when struck by the ground, and guide airflow around the rear
wheels of the
vehicle to reduce its aerodynamic resistance when moving.
U.S. Pat. Publication No. 2008/0296930 by Roush et al., describes a trailer
fairing
or fairing for reducing aerodynamic drag from trailer landing gear and/or
wheel assembly
wherein one or more fairings is directly connected to the forward facing
structural supports
of the landing gear, or to the underside of the trailer, in order to reduce
the aerodynamic
drag of the wheel assembly or landing gear.
Also, various converter dollies are known which include fenders of various
sizes and
shapes. However, these are typically provided only to prevent water spray, or
the like,
and/or to protect the wheels. They provide little or no aerodynamic benefits.
Summary of the Invention
The advantages set out hereinabove, as well as other objects and goals
inherent
thereto, are at least partially or fully provided by the trailer converter
dolly fairings of the
present invention, as set out herein below.
In accordance with one aspect of the present invention, therefore, there is
provided
a converter dolly apparatus comprising a support frame, a wheel assembly, a
fifth wheel
assembly, and a hitching apparatus, and additionally comprising at least one
drag
reduction, aerodynamic dolly fairing, attached to the converter dolly
apparatus, and
positioned in front of at least one wheel assembly.
Typically, a converter dolly will have a wheel assembly comprising at least
one
wheel on each side of the dolly, connected to each other through an axle. More
typically, a
single axle dolly will have two wheels located on either side of the dolly.
Preferably, the
converter dolly of the present invention, will include two dolly fairings,
attached to the dolly,
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which are located in front of the wheel, or wheels, located on each side of
the converter
dolly. It will be noted, however, that use of a single fairing, mounted on the
converter dolly,
and which extends across the dolly in front of both sets of wheels, is not
excluded from the
present invention.
Dual axle dollies are also known in which two axles are provided. In this
embodiment, wheel sets of two wheels are typically provided on each axle, on
each side of
the dolly. As such, the phrase "wheel assembly" includes an' of these types of
arrangements.
The dolly fairings can have any suitable shape and size, and can include
angled
plates, or the like, positioned in front of the wheels. Preferably, however,
the converter dolly
comprises two aerodynamic dolly fairings, each of which is located on a side
of the
converter dolly, in front of the wheels. The fairings can have any suitable
aerodynamic
shape so as to provide an improved aerodynamic effect. For example, the
fairings can be
horizontally or vertically angled flat plates, horizontally or vertical "V-
shaped" plates, curved
or conical shaped, or include pyramidal sections or the like. In one preferred
embodiment,
the dolly fairings have an aerodynamic shape which includes a section which
can be
described as a curved, hollow, frusto-conical section having a base, which is
open towards,
or around the wheels.
The dolly fairings can extend forwards or rearwards, to suit the individual
environment. The dolly fairings can also extend rearward to cover the top or
outside of the
wheels, although this approach is not typically preferred since it might
interfere with
checking or adjustment of the wheel lug nuts, or the like.
The dolly fairings are preferably located so as to be below the level of the
dolly fifth
wheel, and thus, not interfere with connection of the additional trailer to
the converter dolly.
The dolly fairings can extend as close to the ground, as is deemed practical,
but typically
and preferably, remain between 5 and 30 cm from the ground, when in use.
The dolly fairing can also include a flexible material secured along at least
a part of
its bottom edge, to minimize damage to the dolly fairing. The flexible
material can include
products such as rubber, or flexible plastic, or the like, and can comprise
between 10% to
25% of the height of the converter dolly fairing. For example, use of a
material such as
EPDM rubber (e.g. ethylene propylene diene monomer (M-class) rubber), secured
along
the bottom of the dolly fairing can provide protection against scuffing or
breaking of the dolly
fairing.
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The height of the flexible material comprises a portion of the overall height
of the
fairing, and when present, preferably accounts for between 10% to 25% of the
overall
height of the dolly fairing.
The dolly fairings are preferably attached to the converter dolly frame, using
any
conventional fastening technique, so that the dolly fairings will not
interfere with the wheels
when the trailer is being turned. The fastening system can be rigid, but
preferably is
somewhat resilient so as to allow the dolly fairing to flex on impact during
any accidental
contact.
As a result of being attached to the dolly, the dolly fairings remain attached
to the
dolly, when the converter dolly is not in regular use. As such, there is no
need to move or
remove the dolly fairings, when the dolly is not in use.
In a further aspect, the present invention also provides a dolly fairing for
use on a
set of wheels in a wheel assembly, which dolly fairing is adapted to be
attached to a
converter dolly.
It will also be noted that the fifth wheel on some converter dollies is
movable
forwardly and rearwardly of the dolly, along the dolly's longitudinal axis.
This is normally
more common on dual axle dollies, and in these embodiments, the dolly fairings
are
preferably attached to the dolly in such a manner that the dolly will not
interfere with the fifth
wheel as it is moved.
The material of the dolly fairings may be chosen from any suitable materials
for this
application. Preferably, the dolly fairings are made from a material selected
from the group
consisting of steel, aluminum, alloys of steel, alloys of aluminum, plastics
such as
polyethylene or polypropylene, reinforced composite plastics materials such as
fibreglass,
thermoset composites, thermoplastic materials (e.g. TPO), and the like.
TPO typically refers to polymer/filler blends usually consisting of some
fraction of
PP (polypropylene), PE (polyethylene), BCPP (block copolymer polypropylene),
rubber, and
a reinforcing filler.
Also, combinations thereof and therebetween, such as sheets of steel
sandwiching
a plastic core, or combinations of different types of composite materials, and
the like, might
be used.
However, any suitable material can be used, and the use of other materials is
not
excluded from the present invention.
Preferably, the dolly fairing is somewhat resilient so that it will return to
its original
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position if deflected as a result of coming in contact with any obstacles.
Also, since the
addition of dolly fairings adds weight to the entire tractor-trailer system,
which can increase
fuel consumption, it is desirable to have a dolly fairing that is as light as
possible. As such,
the use of light-weight, dolly fairings located immediately in front of the
dolly wheels, is of
greatest utility in the practise of the present invention.
Brief Description of the Drawing
The novel features which are believed to be characteristic of the present
invention,
as to its structure, organization, use and method of operation, together with
further
objectives and advantages thereof, will be better understood from the
following drawings in
which a presently preferred embodiment of the invention will now be
illustrated by way of
example. It is expressly understood, however, that the drawings are for the
purpose of
illustration and description only and are not intended as a definition of the
limits of the
invention. Embodiments of this invention will now be described by way of
example only, in
association with the accompanying drawings in which:
Figures lA and 1B are side and top views of a single axle, prior art converter
dolly;
Figure 2 is a side view of a prior art converter dolly in position between two
trailers;
Figure 3 is a perspective view of a converter dolly of the present invention,
with
converter dolly fairings attached;
Figures 4 and 5 are top and side views of the converter dolly shown in Figure
3;
Figure 6 is a further perspective view of the converter dolly shown in Figure
3;
Figure 7 is a perspective view of a tractor-trailer assembly utilizing the
converter
dolly of the present invention; and
Figure 8 is a perspective view of a tandem axle converter dolly, according to
the
present invention.
Detailed Description of the Preferred Embodiments
The novel features which are believed to be characteristic of the present
invention,
as to its structure, organization, use and method of operation, together with
further
objectives and advantages thereof, will be better understood from the
following drawings in
which a presently preferred embodiment of the invention will now be
illustrated by way of
example only. In the drawings, like reference numerals depict like elements.
It is expressly understood, however, that the drawings are for the purpose of
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illustration and description only and are not intended as a definition of the
limits of the
invention. Also, unless otherwise specifically noted, all of the features
described herein may
be combined with any of the above aspects, in any combination.
Referring to the drawings, and particularly to Figures lA and 1B, a single
axle
converter dolly 10, in accordance with the prior art, is shown. Dolly 10
includes a frame
section 12, to which a wheel assembly 14 is attached. Wheel assembly 14
includes wheels
16 located on each side of dolly 10, and a connecting axle 18 which connects
wheels 16 to
each other.
A hitching apparatus, which in this case is an pintle eye 20 is fitted to the
front of
frame 12, and is adapted to connect to an pintle hook 22, located at the rear
of a first trailer
24, as seen in Figure 2. Any suitble trailer hitching means can be used,
however, including
ball-type trailer hitches, and the like. A pintle eye and hook (or hitch) are
most preferred
however.
A fifth wheel assembly 26 is fitted on the top of frame 12, and is orientated
so that a
further, second trailer 28, can be attached to dolly 10, by use of the fifth
wheel.
Commonly mud-flaps 32 are provided to control water spray, and the like, but
these
provide little or no aerodynamic benefits.
Dolly 10 also includes a variety of air hoses, support stands, chains,
electrical
connectors, and the like, in accordance with current practises.
In Figure 2, the use of connector dolly 10 to connect a second trailer 28 to a
first
trailer 24, can clearly be seen.
In Figures 3 to 6, a converter dolly 40 of the present invention is shown
comprising
a frame 42, to which a wheel assembly 44 is attached. Wheel assembly 44
includes wheels
46 located on each side of dolly 40, and a connecting axle 48 which connects
wheels 46 to
each other. A hitching apparatus, which in this case is an pintle eye 50 is
fitted to the front
of frame 42, and is adapted to connect to an pintle hook (not shown) of a
first trailer. A fifth
wheel assembly 56 is fitted on the top of frame 42, and is orientated so that
a further,
second trailer can be attached to dolly 40, by use of the fifth wheel.
In Figures 3 to 6, two dolly fairings 60 are fitted to frame 42. Fairings 60
are hollow,
made of composite reinforced fibreglass, and are located on each side of dolly
40. Fairings
60 are aerodynamically shaped, and are positioned immediately in front of
wheels 46. At a
front section of fairings 60 is a section 62 generally having a frusto-conical
shape, and an
open rear-ward section 64 which is open towards wheels 46. Preferably the
dolly fairings on
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either side of the converter dolly are mirror images of each other, so that
the installation of
the dolly fairings on the dolly of the present invention, is preferably
essentially symmetrical.
It can thus be noted that in Figures 3 to 6, and Figure 4 in particular, that
the left-
hand fairing is the mirror image of the right-hand fairing. It can also be
seen that the fairings
on the dolly have a more curved outer surface, with respect to the
longitudinal axis of the
dolly, while the inner surface is more angled. Also, it can be seen that for
the wheel
assembly shown in Figures 3 to 6, the front of the fairing is shaped so that
its leading edge
is located inside of the outermost wheel, on each side of the dolly. This
provides a
stabilizing effect on the dolly, during use.
In Figure 7, a perspective view of a tractor-trailer system is shown having a
tractor
70 with a first trailer 72 connected to tractor 70. At the back of trailer 72
is a converter dolly
40 of the present invention, to which is attached a second trailer 74.
In Figure 8, a dual axle dolly 80 is shown, having a frame 82, a fifth wheel
84, an
attachment pintle eye 86, and two wheel assemblies 88 and 90, and each having
two
wheels 92 on each side of dolly 80. Each wheel assembly 88 and 90 has an axle
94
connecting the two wheels 92 on each side of dolly 80 to the corresponding two
wheels 92
on the other side of dolly 80. In front of each set of wheels 92 of wheel
assembly 88, is a
dolly fairing 96, according to the present invention. It is also noted, that
fifth wheel 84 is
movable along the longitudinal axis of dolly 80, by use of locking set 98.
There has thus been described a converter dolly fairing system which may be
employed to reduce the drag on a towed trailer, particularly one which is
being towed at
high speed along a highway, by use of a converter dolly. Thus, it is apparent
that there has
been provided, in accordance with the present invention, a converter dolly
which fully
satisfies the goals, objects, and advantages set forth hereinbef ore.
Therefore, having
described specific embodiments of the present invention, it will be understood
that
alternatives, modifications and variations thereof may be suggested to those
skilled in the
art, and that it is intended that the present specification embrace all such
alternatives,
modifications and variations as fall within the scope of the appended claims.
Additionally, for clarity and unless otherwise stated, the word "comprise" and
variations of the word such as "comprising" and "comprises", when used in the
description
and claims of the present specification, is not intended to exclude other
additives,
components, integers or steps. Further, the invention illustratively disclosed
herein suitably
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may be practiced in the absence of any element which is not specifically
disclosed herein.
Moreover, the words "substantially" or "essentially", when used with an
adjective or
adverb is intended to enhance the scope of the particular characteristic;
e.g., substantially
planar is intended to mean planar, nearly planar and/or exhibiting
characteristics associated
with a planar element. Also, terms such as "forwardly", "rearwardly", "up" or
"down", or the
like, are used in their normal sense which respect to the use of the dolly in
its normal
operation.
Further, use of the terms "he", "him", or "his", is not intended to be
specifically
directed to persons of the masculine gender, and could easily be read as
"she", "her", or
"hers", respectively.
Also, while this discussion has addressed prior art known to the inventor, it
is not an
admission that all art discussed is citable against the present application.
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