Title: Tank apparatus with open weave reinforcing patch structure
Abstract: A filament-wound tank portion of an electric water heater has a wall opening through which an electric heating element of other structure extends into the interior of the tank. The opening is reinforced by a stacked series of single layer, open weave patch members which are interdigitated with layers of the filament winding and through which the opening extends. The filament winding and the patches are impregnated with and intersecured by a cured resin material. As an alternative to cutting portions of the patches during formation of the tank wall opening, the patches may be provided with suitable pre-formed openings with reinforced peripheries, the subsequently formed tank wall opening extending through these reinforced, pre-formed patch openings. The single layer, open weave patches are also utilized to reinforce other types of filament-based tank wall structures.
Patent Number: 6,898,373 Issued on 05/24/2005 to Jackson
| Inventors:
|
Jackson; Barry N. (Woodbury, MN)
|
| Assignee:
|
Rheem Manufacturing Company (New York, NY)
|
| Appl. No.:
|
667621 |
| Filed:
|
September 22, 2003 |
| Current U.S. Class: |
392/451; 156/166; 220/590 |
| Intern'l Class: |
F24H 001/20 |
| Field of Search: |
156/166-180
220/590
392/441-449
|
References Cited [Referenced By]
U.S. Patent Documents
Primary Examiner: Campbell; Thor S.
Attorney, Agent or Firm: Konneker & Smith, P.C.
Claims
1. Filament-wound tank apparatus comprising:
a tank;
a wound filament structure extending externally around and reinforcing said tank
in a circumscribing relationship therewith, said wound filament structure having
an outer surface;
at least one single layer, open weave reinforcing patch disposed between said
tank and said outer surface of said wound filament structure and being secured
to said wound filament structure; and
an opening extending into the interior of said tank from said outer surface of
said wound filament structure and through said at least one single layer, open
weave reinforcing patch.
2. The filament-wound tank apparatus of claim 1 wherein:
said tank is a water heater storage tank.
3. The filament-wound tank apparatus of claim 1 wherein:
said tank is of a non-metallic construction.
4. The filament-wound tank apparatus of claim 1 wherein:
said tank is of a plastic construction.
5. The filament-wound tank apparatus of claim 1 wherein:
said tank is of a blow-molded plastic construction.
6. The filament-wound tank apparatus of claim 1 wherein:
said at least one single layer, open weave reinforcing patch is imbedded in said
wound filament structure.
7. The filament-wound tank apparatus of claim 1 wherein:
said wound filament structure is defined by a multi-layer filament winding impregnated
with a cured resin material, and
said at least one single layer, open weave reinforcing patch is impregnated with,
and adhered to said wound filament structure by, said cured resin material.
8. The filament-wound tank apparatus of claim 1 wherein:
said at least one single layer, open weave reinforcing patch is a stacked series
of single layer, open weave reinforcing patches interdigitated with layers of said
wound filament structure, said opening extending through each patch.
9. The filament-wound tank apparatus of claim 8 wherein:
each of said single layer, open weave reinforcing patches has a pre-formed hole
extending therethrough and through which said opening passes, said pre-formed hole
having a reinforced periphery.
10. The filament-wound tank apparatus of claim 1 wherein:
said at least one single layer, open weave reinforcing patch has a pre-formed
hole therein through which said opening extends.
11. The filament-wound tank apparatus of claim 10 wherein:
said at least one single layer, open weave reinforcing patch is imbedded in said
wound filament structure.
12. The filament-wound tank apparatus of claim 10 wherein:
said pre-formed hole has a reinforced periphery.
13. The filament-wound tank apparatus of claim 1 wherein:
said tank has a generally cylindrical configuration with a side wall portion,
and
said opening extends through said side wall portion.
14. The filament-wound tank apparatus of claim 1 further comprising:
a structure sealingly extending through said opening into said tank.
15. A water heater comprising:
a tank adapted to hold a quantity of water to be heated;
a wound filament structure extending externally around and reinforcing said tank
in a circumscribing relationship therewith, said wound filament structure having
an outer surface;
at least one single layer, open weave reinforcing patch disposed between said
tank and said outer surface of said wound filament structure and being secured
to said wound filament structure;
an opening extending into the interior of said tank from said outer surface of
said wound filament structure and through said at least one single layer, open
weave reinforcing patch;
heating apparatus for heating water in said tank;
a jacket structure extending outwardly around said wound filament structure and
forming therebetween a cavity; and
insulation disposed within said cavity.
16. The water heater of claim 15 wherein:
said water heater is an electric water heater, and
said heating apparatus includes an electric heating element sealingly extending
through said opening into the interior of said tank.
17. The water heater of claim 15 wherein:
said tank is of a non-metallic construction.
18. The water heater of claims
15 wherein:
said tank is of a plastic construction.
19. The water heater of claim 15 wherein:
said tank is of a blow-molded plastic construction.
20. The water heater of claim 15 wherein:
said at least one single layer, open weave reinforcing patch is imbedded in said
wound filament structure.
21. The water heater of claim 15 wherein:
said wound filament structure is defined by a multi-layer filament winding impregnated
with a cured resin material, and
said at least one single layer, open weave reinforcing patch is impregnated with,
and adhered to said wound filament structure by, said cured resin material.
22. The water heater of claim 15 wherein:
said at least one single layer, open weave reinforcing patch is a stacked series
of single layer, open weave reinforcing patches interdigitated with layers of said
wound filament structure, said opening extending through each patch.
23. The water heater of claim 22 wherein:
each of said single layer, open weave reinforcing patches has a pre-formed hole
extending therethrough and through which said opening passes, said pre-formed hole
having a reinforced periphery.
24. The water heater of claim 15 wherein:
said tank has a generally cylindrical configuration with a side wall portion,
and
said opening extends through said side wall portion.
25. The water heater of claim 15 wherein:
said at least one single layer, open weave reinforcing patch has a pre-formed
hole through which said opening extends.
26. The water heater of claim 27 wherein:
said preformed hole has a reinforced periphery.
27. The water heater of claim 15 further comprising:
a structure sealingly extending through said opening into said tank.
28. Tank apparatus comprising:
a filament-based wall structure;
a single layer, open weave reinforcing patch secured to said wall structure;
and
an opening extending into the interior of said tank apparatus through said wall
structure and said reinforcing patch.
29. The tank apparatus of claim 28 wherein:
said tank apparatus is a water heater storage tank.
30. The tank apparatus of claim 28 further comprising:
a structure sealingly extending through said opening into the interior of said
tank apparatus.
31. The tank apparatus of claim 28 wherein:
said reinforcing patch is imbedded in said filament-based wall structure.
32. The tank apparatus of claim 28 wherein:
said filament-based wall structure has an interior surface defining the interior
surface of said tank apparatus.
33. The tank apparatus of claim 28 wherein:
said tank apparatus further comprises an inner tank body reinforcingly enveloped
by said filament-based wall structure.
34. The tank apparatus of claim 28 wherein:
said wall structure and said reinforcing patch are intersecured by a cured resin
material portion of said wall structure.
35. The tank apparatus of claim 28 wherein:
said wall structure comprises a filament winding material impregnated with a
cured resin material.
36. The tank apparatus of claim 28 wherein:
said wall structure comprises chopped fiber material impregnated with a cured
resin material.
37. The tank apparatus of claim 28 wherein:
said reinforcing patch has a pre-formed hole therein through which said opening
extends.
38. The tank apparatus of claim 37 wherein:
said pre-formed hole has a reinforced periphery.
39. A water heater comprising:
tank apparatus for storing a quantity of water to be heated, said tank apparatus
including a filament-based wall structure, a single layer, open weave reinforcing
patch secured to said wall structure, and an opening extending into the interior
of said tank apparatus through said wall structure and said reinforcing patch;
heating apparatus for heating water in said tank apparatus;
a jacket structure extending outwardly around said tank apparatus and forming
therebetween a cavity; and
insulation disposed within said cavity.
40. The water heater of claim 39 further comprising:
a structure sealingly extending through said opening into the interior of said
tank apparatus.
41. The water heater of claim 39 wherein:
said reinforcing patch is imbedded in said filament-based wall structure.
42. The water heater of claim 39 wherein:
said filament-based wall structure has an interior surface defining the interior
surface of said tank apparatus.
43. The water heater of claim 39 wherein:
said tank apparatus further comprises an inner tank body reinforcingly enveloped
by said filament-based wall structure.
44. The water heater of claim 39 wherein:
said wall structure and said reinforcing patch are intersecured by a cured resin
material portion of said wall structure.
45. The water heater of claim 39 wherein:
said wall structure comprises a filament winding material impregnated with a
cured resin material.
46. The water heater of claim 39 wherein:
said wall structure comprises chopped fiber material impregnated with a cured
resin material.
47. The water heater of claim 39 wherein:
said water heater is an electric water heater.
48. The water heater of claim 39 wherein:
said reinforcing patch has a pre-formed hole therein through which said opening
passes.
49. The water heater of claim 48 wherein:
said pre-formed hole has a reinforced periphery.
Description
BACKGROUND OF THE INVENTION
The present invention generally relates to pressure vessels, such as water heater
storage tanks and, in a preferred embodiment thereof, more particularly provides
a filament-wound plastic water heater tank in which a specially designed patch
structure is utilized to reinforce an opening extending inwardly through the exterior
filament winding and the tank wall.
Filament-wound pressure tanks, such as those incorporated in various
types of water heaters, are typically constructed using an inner tank body which
may be representatively of a blow-molded plastic construction. To reinforce the
inner tank body it is exteriorly wound with a resin-impregnated filament, such
as a fiberglass filament material, in a combination of helical and circumferential
wraps such that the finished filament winding comprises a series of filament material
layers. The applied filament winding on the exterior of the tank body is then cured
to harden it to thereby substantially reinforce the tank body to permit it to handle
internal operating pressure levels that It might not otherwise be able to withstand.
If the filament-wound tank requires the formation of a wall opening therein,
such
as a heating element sidewall opening in a water heater tank, it is necessary to
cut the filament fibers to extend the opening into the tank interior. This hole-cutting
operation substantially weakens the exterior reinforcing portion of the overall
tank structure. To compensate for this weakening, one or more reinforcing patches
are applied to the tank structure. These patches are designed to help tie the cut
filament fibers to each other and to different layers of the filament winding.
Conventionally, these reinforcing patches are of a multi-layered
triaxial design, with different fiber directions in the layers, and are customarily
of a tight weave, sometimes being knitted to retain their shape and body. The multilayered
tight-weave patches are applied to the tank within the various filament winding
layers to reinforce the area and fibers that will be cut when the tank opening
is subsequently formed. Each patch is soaked in the resin material to help bond
it to the layers of the filament winding, with each patch being of a very tight
weave and thick construction to help transfer the load in the different directions
of the windings around the tank. The design goal of utilizing this type of patch
structure is to cause the installed tight weave, multilayer patches to bond to
the different layers of the filament windings with the resin soaked into the patch
and the filament fibers.
In the formation of filament-wound tanks (as well as filament-based tanks of
various
non-wound varieties), this conventional patch reinforcing technique has several
problems, limitations and disadvantages. For example, this type of patch structure
is often prone to failure, thereby substantially weakening the strength of the
tank, due to delamination of the various individual patch elements caused by stress
on their outer layers by filament windings bonded thereto. This problem arises
from the difficulty of adequately resin-bonding the various layers of each individual
patch member to one another. Additionally, it is often difficult to assure that
resin flows completely through each patch. Moreover, the conventional large thickness
of these multilayer patches undesirably places additional stress on the contiguous
filament layers by causing them to sharply bend around the patch edges.
As can be readily seen from the foregoing, a need exists for an improved hole-reinforcing
patch technique in the production of filament-based pressure tanks such as the
filament winding reinforced water storage tank portions of water heaters. It is
to this need that the present invention is directed.
SUMMARY OF THE INVENTION
In carrying out principles of the present invention, in accordance with a preferred
embodiment thereof, an electric water heater is provided with a specially designed
filament-wound water storage tank apparatus disposed within an outer jacket, a
cavity disposed between the tank apparatus and jacket structure being filled with
a suitable insulation material. Heating apparatus including an immersible electric
resistance heating element is provided for heating water stored in the tank structure
for on-demand delivery therefrom.
From a broad perspective, the tank structure in a representative embodiment
thereof includes a tank which is representatively of a blow-molded plastic construction
and adapted to hold a quantity of water to be heated, and a wound filament structure
extending externally around and reinforcing the tank. At least one single layer,
open weave reinforcing patch is disposed between the tank and the outer surface
of the wound filament structure and is secured to the wound filament structure,
illustratively by a cured resin material with which the filament winding portion
of the wound filament structure and the at least one single layer, open weave reinforcing
patch are impregnated. An opening, which sealingly receives the electric heating
element (or some other structure extending into the tank), extends into the interior
of the tank from the outer surface of the wound filament structure and through
the at least one single layer, open weave reinforcing patch. The tank opening may
extend through a side wall portion or an end wall portion of the tank, and the
tank may be provided with more than one reinforced side wall and/or end wall openings.
In an illustrated embodiment of the filament-wound tank apparatus a stacked series
of single layer, open weave reinforcing patches are imbedded in the wound filament
structure and interdigitated with layers of the filament winding thereof, the tank
opening which sealingly receives the electric heating element extending through
holes in the individual patches which are created when the element opening is cut
through the wound filament structure and a wall portion of the underlying tank
body. Alternatively, a single patch, imbedded in the filament winding or placed
directly against the inner tank body, may be used in suitable applications. As
another alternative, the patches may have pre-formed holes therein through which
the subsequently formed element opening passes. The pre-formed holes in the patches
have peripheries which may be reinforced, as by a knitting or weaving procedure.
The use of single layer, open weave patches imbedded in the wound filament structure
or placed directly against the inner tank body permits resin applied to the filament
winding and/or to the patches to easily flow into, around and through the patches
to allow a more thorough and complete resin bonding between and among the patch
and winding fiber portions of the overall reinforcing structure surrounding the
underlying tank body. Moreover, the use of single layer, open weave reinforcing
patches substantially eliminates the problem of patch delamination, and also reduces
the stress-inducing bending of the filament winding at the patch edges.
In other forms of the invention, the filament portion of the tank structure may
be of a non-wound type (such as chopped fiberglass, for example), and the finished
tank structure may lack an inner tank body, the tank wall being defined by a filament-based
material deposited externally on a subsequently removed bladder or mandrel structure.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified, partially sectioned side elevational view of an upper
portion of an electric water heater embodying principles of the present invention;
FIG. 2 is a simplified, partially sectioned side elevational view of a specially
designed filament wound storage tank portion of the water heater which has been
removed from the water heater for illustrative purposes;
FIG. 3 is an enlarged scale schematic cross-sectional view through a portion
of a unique tank hole-reinforcing structure incorporated in the tank;
FIGS. 4-7 are enlarged scale side elevational views of portions of representative
single layer, open weave patches used in the overall reinforcing patch structure; and
FIG. 8 is a schematic cross-sectional view through an alternate fiber-based
tank structure also embodying principles of the present invention.
DETAILED DESCRIPTION
Referring initially to FIGS. 1 and 2, in a preferred embodiment thereof,
the present invention provides an electric water heater
10 (an upper portion
of which is shown in FIG. 1) having a specially designed filament-wound water storage
tank portion
12 incorporated therein and adapted to hold a quantity of pressurized
water
14 to be heated for on-demand delivery from the tank. Tank
12
has an inner body portion
16, representatively of a blow-molded plastic
construction, from the upper end of which three pipe sections upwardly extend—a
cold water inlet pipe
18, a hot water outlet pipe
20, and a temperature
and pressure relief pipe
22 If desired, a variety of other materials could
be utilized for the inner body portion
16 including, but not limited to,
injection molded plastic and metal.
The inner tank body portion
16 is externally reinforced by means of a
resin-impregnated filament winding structure
24 (representatively a fiberglass
filament material) which is wrapped around the outer surface of the tank body
16,
in a series of layers, in a combination of helical and circumferential wraps. After
the winding structure
24 is applied to the inner tank body portion
16
it is hardened thereon by a suitable resin curing process. Alternatively, another
filament or fiber-based reinforcing material (such as, for example, a chopped fiberglass
material) could be substituted for the winding structure in certain applications
without departing from principles of the present invention.
Extending outwardly around the tank
12 is an outer jacket structure
26 which defines around the tank
12 an insulation cavity
28
filled with a suitable insulation material
30, representatively hardened
foam insulation material As illustrated in FIG. 1, the pipes
18,
20,
22
extend outwardly through an upper end portion of the jacket
26.
Heating apparatus is provided for heating the pressurized water
14
stored in the tank
12 and representatively includes a schematically depicted
electrical resistance immersion type heating element
32 sealingly extending
into the interior of the tank
12 through an opening
34 cut through
the filament winding
24 and a sidewall portion of the inner tank body
16
after the formation of the tank
12.
According to a key aspect of the present invention, a specially designed
patch structure
36 which circumscribes the opening
34 is incorporated
in the tank
12 and serves to reinforce it around the opening
34 by
substantially reducing the filament weakness around the periphery of the opening
34 caused by the cutting of the filament fibers bordering it.
Referring now to FIGS. 2-4, patch structure
36 representatively
comprises a stacked series of single layer, open weave patch members
38
interdigitated with and resin-bonded to layers of the filament winding
24—filament
winding layers
24a-
24d being illustratively shown in
FIG. 3, with layer
24a being the outermost filament layer. A portion
of one of the individual single layer, open-weave patches
38 is shown in
FIG.
4. Representatively, each patch member
38 may be formed from
a variety of suitable materials such as, for example, fiberglass, carbon, kevlar,
etc. As can be seen in FIG. 4, each patch member
38 has a spaced series
of parallel individual strands
40 secured at an angle (representatively
ninety degrees) to another spaced series of parallel individual strands
42,
with substantial through-holes
44 bordered by the individual strands
40,
42
being present in the patch
38.
The use of the single layer, open weave patch members
38 to reinforce
the tank hole
34 provides various advantages compared to conventionally
utilized patch methods for doing so. For example, the use of an open weave type
patch desirably permits resin to flow around the patch fibers and through the open
weave to lock the patch in place and to completely bond it to the other layers
in the outer reinforcing portion of the overall tank structure. This better allows
the patch fibers or strands to transfer the load on the tank fibers around the
tank hole without the prior problems of patch delamination. Allowing the resin
to completely flow in, around and through each patch allows a more complete bonding
between all of the layers of the tank. Additionally, the single layer nature of
each patch substantially prevents the stress-inducing sharp bending of the winding
filaments contiguous with the edges of the installed patches.
While each of the individual patches
38 is illustratively shown as being
of a single strand variety, with each of the sets of strands
40,
42
being of the same material, and the strand sets being generally perpendicular to
one another, a variety of other patch configurations could be utilized If desired.
For example the weave can be of different types, shapes and size as long as it
is an open weave pattern. The open weave pattern can be adjusted to suit different
strength requirements. It can be vary from single strand construction with small
openings to multiple woven strands with relatively large openings. The weave pattern
could be different in the weft and warp directions to suit the specific loading
direction in the application, and other configurational modifications could be
made to the patches without departing from principles of the present invention.
Additionally, while the patches are shown as being interdigitated with the various
filament winding layers, it will be appreciated that the innermost patch could
be placed directly against the outer surface of the inner tank body if desired.
Moreover, while the patch structure has been representatively illustrated as comprising
a stacked series of individual patches, in suitable applications it could alternatively
be defined by a single patch—either imbedded in the filament winding or
other filament or fiber-based material, or placed directly against the inner tank body.
As an example of one possible alternate type of patch, the portion of the single
layer, open weave patch
38a shown in FIG. 5 is of a single layer,
open weave construction in which each of the strands
40a,
42a
is formed from a group of individual patch strands
40 or
42 as
opposed to the single strand patch construction shown in FIG.
4. As an example
of another possible type of alternate patch, the portion of the single layer, open
weave patch
38b shown in FIG. 6 has strand structures
40b,
42b
formed each formed from multiple individual strands, and has smaller through-openings
44b.
As previously described herein, the tank opening
34 is illustratively
formed
by cutting through the filament winding
24 and the individual patch portions
38 of the patch structure
36 after the patches
38 have been
operatively disposed in the filament winding. According to another aspect of the
present invention, shown in FIG. 7 in conjunction with the alternate patch member
embodiment
38c, openings
46 may be pre-formed in each of the
patch members
38c prior to their operative placement in the filament
winding structure
24, with the peripheries
48 of the patch openings
46 being reinforced by, for example, weaving or knitting the patch fibers
around the periphery of the pre-formed opening
46. Alternatively, pre-formed
patch holes without reinforced peripheries could be utilized.
When the patches
38c, with their preformed, reinforced openings
46 are interdigitated with and resin-bonded to the various layers of the
filament winding structure
24 the patch openings
46 (which may be
slightly larger than the tank opening
34) are aligned with the location
of the still to be formed tank opening
34. Thus, when the tank opening
34
is later formed only the filament winding layers are cut—no cutting of any
of the patch strands results from this hole cutting operation.
While the present invention has thus far been representatively illustrated
and described as being incorporated in the storage tank portion of a water heater,
it is to be clearly understood that principles of the invention are in no manner
limited to water heaters and can alternatively be utilized to advantage in conjunction
with a variety of other types of filament-wound or other filament or fiber-based
pressure vessels. Similarly, while the patch-based hole reinforcement technique
representatively illustrated and described herein has been used in conjunction
with a tank hole through which an electric heating element is operatively inserted,
such technique can also be utilized in conjunction with a wide variety of other
structures inserted through a tank hole. Further, the patch-based vessel reinforcing
techniques illustrated and described herein may be used to reinforce vessel holes
located in portions of vessels other than their sidewalls.
Cross-sectionally depicted in schematic form in FIG. 8 is a portion
of an alternate embodiment
12a of the previously described tank
12.
Tank
12a has a filament or fiber-based wall structure
48 which
surrounds the interior
50 of the tank
12a, the wall structure
48 being representatively defined by layers
52, which may be filament
winding layers, chopped fiber layers or other types of fiber/filament layers, impregnated
with a cured resin material and interdigitated with single layer, open weave patch
members
38 as previously described in conjunction with the tank
12.
The patch members
38 are locked to the filament layers
52 by the
cured resin material impregnating the entire wall structure
48, and the
reinforced opening
34 extends into the tank interior
50 through the
interdigitated patch members
38 and filament layers
52. The opening
portions extending through the patch members
38 may be formed when the opening
34 is formed through the wall structure
48, of the patch members
38 may have pre-formed, reinforced holes formed therethrough as previously
described in conjunction with the patch member
38c shown in FIG.
7.
It should be noted that the tank apparatus
12a schematically shown
in FIG. 8 is not provided with an inner tank body which is reinforced by the filament/fiber-based
wall structure
48. Instead, the interior surface
54 of the wall structure
48 defines the interior surface of the finished tank apparatus
12a.
This is achieved by forming the wall structure
48 on the outer surface of
an appropriately shaped mandrel or bladder
56 (shown in phantom in FIG.
8) which is removed after the formation thereon of the filament/fiber-based wall
structure
48.
The foregoing detailed description is to be clearly understood as being given
by way of illustration and example only, the spirit and scope of the present invention
being limited solely by the appended claims.
*
