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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is generally related to heat exchanger assemblies
and, more particularly, to heat exchanger assemblies which are formed by
bending a planar heat exchanger element into a generally cylindrical shape
and connecting two end surfaces of the generally cylindrical heat
exchanger element together with specially formed brackets.
2. Description of the Prior Art
Many different types of heat exchanger coils are well known to those
skilled in the art. For example, planar heat exchanger assemblies are
commonly used in condensers of air conditioning systems. It is also known
to combine planar assemblies to form A-coils that are well known for use
as evaporators in air conditioning systems. For certain applications, it
is also known to bend a generally planar heat exchanger element into a
cylindrical shape and direct an air flow radially through the heat
exchanger. This type of cylindrical heat exchanger assembly has been used
for many years in condenser applications for home air conditioning systems
and, more recently, cylindrical evaporators have been developed for
inclusion within the plenum chamber of a furnace for use as an evaporator
in an air conditioning system.
When planar coils are connected together to form A-coils, they are
typically attached to each other or to additional plate components with
sheet metal screws or other mechanical fastening techniques. When planar
coils are bent to form cylindrical heat exchanger assemblies, opposing end
surfaces of the assembly are attached to each other using an intermediate
plate surface that is mechanically attached to both brackets on opposing
end surfaces of the bent heat exchanger. Although certain non-heat
exchanging components have been manufactured which utilize brackets that
are shaped to be received in locking association when disposed proximate
to each other and placed under a separating force, this technique has not
been applied to heat exchangers. Instead, known methods for attaching the
opposing end surfaces of cylindrical heat exchangers utilize additional
components, such as connector plates, attached between opposing brackets
with mechanical fasteners used to connect each bracket to the connector
plate.
U.S. Pat. No. 4,340,015, which issued to Wright et al on July 20, 1982,
discloses the use of a fastener strip that is shaped to receive
specifically bent end portions of a heat exchanger condenser cover. It
provides an apparatus for encasing a heat exchanger unit. A wrapper is
disclosed which comprises solid portions for structural support of the
heat exchanger unit and fastening means including closure means formed on
each end of the wrapper with a fastener strip which co-operates with the
closure means to secure the wrapper in an appropriate position. While
disclosing interlocking bent portions of sheet metal components, this
patent requires the use of an additional separate component, such as its
fastener strip, to maintain opposing ends of a cover in a predetermined
relationship to each other.
U.S. Pat. No. 2,625,804, which issued to Patch et al on Jan. 20, 1953,
discloses an over-center latch for maintaining the end surfaces of a
cooler band in a predetermined position and maintained the cooler band in
a restrictive association with a barrel in a barrel cooling apparatus. The
invention relates to a cooling and dispensing device for beverages and,
more particularly, describes a device for holding a barrel of beverage in
place within the cooling apparatus.
U.S. Pat. No. 3,260,305, which issued to Leonard et al on July 12, 1966,
describes a folded radiator design for use in association with a space
satellite power plant. The radiators are capable of being wrapped around a
generally cylindrical assembly and then unfolded to extend radially away
from the cylindrical assembly. This patent does not disclose a means for
interlocking the opposing end surfaces of a generally cylindrical heat
exchanger.
The field of heat exchanger technology can be significantly enhanced by
providing a means for maintaining the end surfaces of a cylindrical heat
exchanger in a predetermined association with each other while also
simplifying the manufacturing procedure and reducing the total number of
components and the total cost required to form a generally cylindrical
heat exchanger from a planar heat exchanger element.
SUMMARY OF THE INVENTION
The present invention provides a heat exchanger assembly in which a planar
heat exchanger element is bent to form a generally cylindrical assembly
with end surfaces that are spaced apart in parallel association with each
other. In addition, the present invention provides a simplified means for
attaching the end surfaces to each other in such a way that they are
maintained in a predetermined configuration. In addition, the present
invention provides means for accomplishing these goals with a
significantly reduced number of components and also makes possible a
simplified procedure of assembly that reduces the number of fixtures and
tools required for attaching the two end surfaces together.
In a preferred embodiment of the present invention, a heat exchanger
assembly comprises a heat exchanger element having two end surfaces,
wherein a planar element is bent to form a generally cylindrical member
with the end surfaces disposed in a parallel association with each other.
In addition, first and second mounting brackets are attached to first and
second ones of the two end surfaces. Each of the mounting brackets is
provided with first, second and third portions. The first portions of each
of the mounting brackets are attached to an associated one of the two end
surfaces and a second portion of each of the brackets extends from the
first portion at a preselected angle. A third portion of each of the
brackets extends from the second portion of the bracket at a second
preselected angle. The third portions of the two brackets are disposed in
generally opposite directions from each other to form an interlocking
arrangement between the brackets. In a preferred embodiment of the present
invention, the second preselected angle is between 0.degree. and
90.degree. inclusively, with a most preferred angle being between
0.degree. and 45.degree. inclusively. The generally cylindrical member of
the assembly is formed to have a relaxed shape that disposes the end
surfaces of the heat exchanger with a space between them. The bent heat
exchanger member is deformable, by the application of a compressive force
which reduces the effective diameter of the cylinder, to cause the third
portions of the two brackets to move into interlocking association with
each other. When the compressive force is released, the heat exchanger
moves partially back toward its relaxed position and causes the third
portions of the two brackets to lock into each other and hold the heat
exchanger assembly in a generally cylindrical shape.
The present invention reduces the number of components, and therefore the
cost of the assembly, by removing the need for an intermediate plate to be
attached mechanically to both of the end brackets. Instead of requiring a
plurality of sheet metal screws, or alternative fastening devices, the two
end brackets are shaped to receive each other in an interlocking
association and the natural forces existing within the heat exchanger
structure, which tend to cause the heat exchanger to move toward its
relaxed shape, naturally hold the two brackets together in a restrictive
manner and prevent the heat exchanger assembly from moving into a
non-cylindrical shape larger than that which is intended. No additional
fastening devices, such as sheet metal screws, are required to hold the
two brackets together and, as a result, to hold the end surfaces of the
heat exchanger element in a appropriate relationship with each other.
BRIEF DESCRIPTION OF THE DRAWING
The present invention will be more fully understood from a reading of the
description of the preferred embodiment in conjunction with the drawing,
in which:
FIG. 1 shows a generally planar heat exchanger element of the prior art
comprising a plurality of tubes connected to a plurality of heat exchanger
plates, or fins;
FIG. 2 is a side view of FIG. 1 showing end brackets attached to end
surfaces of the heat exchanger element;
FIG. 3 shows a heat exchanger element of the prior art which is bent from a
generally flat shape into a generally cylindrical shape with end surfaces
disposed in a generally parallel relation with each other with a space
therebetween;
FIG. 4 shows the brackets of the heat exchanger assembly of the prior art
with an additional connector plate and sheet metal screws;
FIG. 5 shows a generally cylindrical heat exchanger made within the scope
of the present invention;
FIG. 6 shows the brackets of the present invention associated in an
interlocking relationship with each other;
FIG. 7 shows a common method used to bend a generally planar heat exchanger
element into a cylindrical shape; and
FIG. 8 shows an end view of a heat exchanger made in accordance with the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Throughout the description of the preferred embodiment, like components
will be referred to with like reference numerals.
FIG. 1 shows a planar heat exchanger that comprises a plurality of heat
exchanger tubes 10 disposed in a generally parallel association with each
other. In addition, a plurality of heat exchanger plates 12, or fins, are
associated in thermal communication with the plurality of tubes 10. The
heat exchanger element shown in FIG. 1 has two end surfaces, 14 and 16.
Each end surface is provided with a bracket. For example, end surface 14
is provided with a bracket 18 and end surface 16 is provided with a
bracket 20. Each of the brackets, 18 and 20, are attached to their
respective end surfaces, 14 and 16.
FIG. 2 shows an end view of the heat exchanger element of FIG. 1. As can be
seen, one row of heat exchanger tubes 10 is provided and connected in
thermal communication with a plurality of heat exchanger fins 12. While
more than one row of heat exchanger tubes can be used, it is advantageous
to use a single row of tubes 10 so that the bending of the heat exchanger
element, as will be described below, is facilitated. As can also be seen
in FIG. 2, the brackets, 18 and 20, are attached to the end surfaces of
the heat exchanger element. As will be described in greater detail below,
the end brackets are each made to comprise first, second and third
portions in a preferred embodiment of the present invention. However, it
should be understood that the heat exchanger element shown in FIGS. 1 and
2 is drawn to represent the type of heat exchanger element that is well
known to those skilled in the art and which does not comprise brackets
that are shaped in accordance with the present invention. The prior art
brackets shown in FIGS. 1 and 2 comprise two straight segments. A first
segment 22 is attached to each of the ends of the heat exchanger element
and another segment 24 extends at a preselected angle from the first
segment.
FIG. 3 shows a generally cylindrical heat exchanger made in accordance with
techniques known to those skilled in the art. The generally planar heat
exchanger element of FIG. 1 has been bent about a central axis. The tubes
10 and heat exchanger fins 12 are formed into the generally cylindrical
configuration shown in FIG. 3. The brackets, 18 and 20, are attached to
the end surfaces of the heat exchanger element and the end surfaces of the
heat exchanger element are associated in a generally parallel
configuration with a space disposed therebetween. FIG. 3 illustrates the
relaxed shape of the bent heat exchanger element. In order to attach the
end surfaces of the heat exchanger together and constrict the heat
exchanger assembly into a cylindrical shape, the extension portions 24 of
the brackets, 18 and 20, must be held together in some manner.
It should be noted that, in FIG. 3, numerous U-shaped tube members are used
to interconnect preselected tubes 10 and additional components, such as
tubing 26 and 28, are shown attached to the heat exchanger. These
additional components are not closely related to the present invention and
will not be described in detail herein.
FIG. 4 shows the end surfaces, 14 and 16 of the heat exchanger shown in
FIG. 3. For purposes of clarity and simplicity, the U-shaped tube
components are not shown in FIG. 4. As can be seen, the brackets 18 and
20, are each provided with a first segment 22 and a second segment 24 with
the second segment 24 extending at some preselected angle from the first
segment 22. The brackets, 18 and 20, are mechanically held together
through the use of an additional component, such as the connector plate
30. The connector plate 30 is mechanically attached to the brackets by use
of sheet metal screws 32. Each of the brackets, 18 and 20, is mechanically
connected to the connector plate 30 by approximately three or more sheet
metal screws. Before describing the advantages of the present invention,
specific attention is directed to FIG. 4 and the illustrated requirement
of a connector plate 30 and a plurality of sheet metal screws 32 to
maintain the end portions, 14 and 16, of the heat exchanger element in the
appropriate association with each other to form the cylindrical heat
exchanger.
FIG. 5 shows a "O" coil heat exchanger made in accordance with the present
invention. By comparing FIGS. 3 and 5, the distinctive differences between
the present invention and the prior art can be seen. The brackets 40 of
the present invention, which will be described in greater detail below in
conjunction with FIG. 6, are shaped in a distinctively different manner
from the brackets, 18 and 20, shown in FIG. 3. The other elements in FIG.
5 are generally similar to those in FIG. 3 and will not be described in
detail herein.
FIG. 6 shows the end portions, 14 and 16 of the heat exchanger element with
the brackets 40 of the present invention attached thereto. Since the two
brackets 40 of the present invention are not exactly identical to each
other, for reasons which will be described below, they will be described
individually. The left bracket in FIG. 6 comprises a first portion 42, a
second portion 44 and a third portion 46. The first portion 42 is attached
to the end surface 16 of the heat exchanger element. It can be formed as
an integral part of the heat exchanger element or, alternatively, can be
mechanically attached to the end surface 16. The second portion 44 extends
from the first portion 42 at a preselected angle to dispose it in an
appropriate location for association with the other bracket. A third
portion 46 of the bracket is disposed at a second preselected angle
relative to the second portion 44. As can be seen, the angle between the
second portion 44 and the third portion 46 forms a hook-like element which
is shaped to receive a similarly configured segment of the other bracket.
Also shown in FIG. 6 is the other bracket 40 which comprises a first
portion 52 which is attached to the end surface 14 of the heat exchanger
element. A second portion 5 extends from the first portion 52 at a first
preselected angle preferably an angle from 10.degree. to 30.degree.
inclusive. The third portion 56 of the bracket is bent to extend at a
second preselected angle preferably from 0.degree. to 90.degree.
inclusive, and even more preferably from 0.degree. to 45.degree. inclusive
from the second portion 54. As can be seen in FIG. 6, the third portions,
46 and 56 of the two brackets extend in opposite directions from each
other so that they can receive each other in a self locking, or
interlocking, relationship brackets can either be integrally formed with
the heat exchanger or separately attachable.
With continued reference to FIG. 6 and with additional reference to FIG. 5,
it can be seen that the third portions, 46 and 56, of the brackets are
shaped to interlock when the end surfaces, 14 and 16, of the heat
exchanger element are forced toward each other by applying a compressive
force to distort the heat exchanger and reduce its effective diameter When
the third portions, 46 and 56 are pushed toward and eventually past each
other, they pass over each other because of the angle of the third
portions with respect to their associated second portions, 44 and 54, and
snap together Each of the third portions 46 and 56, are specifically
shaped to receive each other in this interlocking association. When the
compressive force is released, the heat exchanger will attempt to return
to its relaxed shape that is shown in FIG. 5. The cooperative angles of
the third portions, 46 and 56, of the brackets of the present invention
prevent this return, as shown in FIG. 6, and limit the heat exchanger to a
partial return toward that relaxed shape. As a result, the heat exchanger
continues to apply a force which attempts to pull the two brackets apart
but, instead, results in holding the two brackets in the interlocking
relationship described above. This maintains the relative positions of the
end surfaces, 14 and 16, at the desired position and maintains the heat
exchanger assembly in a generally cylindrical shape.
As described above, the present invention is applicable to heat exchangers
that are formed by bending a planar heat exchanger element into a
generally cylindrical shape. This technique is well known to those skilled
in the art and is illustrated in FIG. 7. In a typical manufacturing
process of this type, a drum 60 is used to roll, or bend, the heat
exchanger element identified by reference numeral 62 around a central axis
which, in this case, is coincident with the axis of rotation of the drum
60. As the drum 60 continues to rotate about its central axis, the
generally planar heat exchanger 62 is bent into the shape illustrated by
reference numeral 64. When the process shown in FIG. 7 is complete, the
heat exchanger is formed into the shape shown in both FIGS. 3 and 5. The
shape is not a complete cylinder but, instead, comprises a slightly larger
diameter because of the relaxed shape of the heat exchanger. However, it
should be understood that the heat exchangers shown in FIGS. 3 and 5 can
be compressed to form a cylinder. When compressed in this manner, some
means can be used to attach the end surfaces of the heat exchanger
elements together to maintain this generally cylindrical shape. FIG. 8
shows the cylindrical shape of the heat exchanger after connecting the
brackets of the present invention together in an interlocking
relationship. In summary, the heat exchanger element, with its tubes 10
and fins 12, is bent into a generally cylindrical shape which is further
held in a more cylindrical form by the action of the brackets.
While the most apparent advantages of the present invention have been
described above, it should also be understood that additional advantages
can be achieved through its use. For example, during manufacturing of the
planar heat exchanger element, it is often painted and cleaned by a
degreasing operation. The angle between the third portion, 46 and 56, and
the second portion, 44 and 54, of the brackets of the present invention
create a hook that can be used to support the heat exchanger element when
in a planar shape and when being painted or cleaned. This hook provides an
incidental benefit that is not available in heat exchangers using the
prior art brackets that are shown in FIG. 4. In addition, while bending
the planar heat exchanger into the generally cylindrical shape, the angle
between the second and third portions of the brackets can be used to hold
the heat exchanger element in position on the drum, such as the drum 60 in
FIG. 7, while removing the necessity of providing additional fasteners
between the heat exchanger and the drum. Although this specific adaptation
is not particularly illustrated in FIG. 7, it should be understood that a
minor adaptation to the drum, and more particularly, the strip 80 shown in
FIG. 7, are relatively simple and easy to accomplish.
Although these additional advantages are also incumbent with the present
invention, the most significant advantage can be seen by comparing FIGS. 4
and 6. In FIG. 4, the connector plate 30 is a necessary additional
component required by the prior art devices. In addition, the plurality of
sheet metal screws 32 are also required. These additional components
require significant time to fabricate and assemble and require the
additional storage of these parts prior to and during assembly.
Another significant advantage of the present invention is related to the
fact that the compressing operation, by which the heat exchanger shown in
FIGS. 3 and 5 is bent to form a cylindrical heat exchanger, requires some
type of fixture to hold the heat exchanger in the deformed shape while an
operator assembles the connector plate 30 to the brackets with the sheet
metal screws 32. One operator cannot easily maintain the compressive force
on the heat exchanger while assembling these numerous parts together In
comparison, the heat exchanger made in accordance with the present
invention can be assembled without the need of an additional fixture to
hold the heat exchanger during the application of the compressive force.
Instead, since the brackets of the present invention are interlocking in
an automatic manner, the compressive force can be applied without the
additional need of a fixture and the end surfaces, 14 and 16 can be pushed
together by reducing the diameter of the assembly and causing the third
portions, 46 and 56, to move toward and eventually past each other because
of the ramp angle provided in the third portions of the brackets. After
passing over each other, by slightly over-bending the assembly during the
compressive deformation, the third portions snap together and capture each
other. This prevents the heat exchanger assembly from completely returning
toward its relaxed shape. Therefore, the assembly operation that attaches
the two brackets together in a device made in accordance with the
preferred embodiment of the present invention, merely requires the
compression of the heat exchanger in a single step operation. No
additional fasteners or connector plates are necessary and no additional
holding fixture is usually needed.
While the preferred embodiment of the present invention has been described
in explicit detail and illustrated with considerable specificity, it
should be clearly understood that alternative embodiments of the present
invention are to be considered within it scope.
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