Water heater having molded plastic storage tank and associated fabrication methods

• US 5,668,922 A
• Filed: 11/16/1995
• Issued: 09/16/1997
• Est. Priority Date: 11/16/1995
• Status: Expired due to Term

• Current Assignee: Rheem Manufacturing Company (Paloma Co., Ltd.)
• Original Assignee: Rheem Manufacturing Company (Paloma Co., Ltd.)
• Inventors: Gantt, Timothy D., Poole, David C., Ross, David O.
• Primary Examiner(s): HOANG, TU BA
• Application Number:
  US08/558,680
• Time in Patent Office: 670 Days
• Field of Search: 392/451, 392/485, 392/341, 392/450, 392/441, 392/444, 392/445, 392/449, 220/444, 220/445, 220/466, 220/4.05, 220/4.13, 220/4.24, 220/4.25, 220/459, 122/13.2
• US Class Current: 392/441
• CPC Class Codes: B29C 65/00 Joining or sealing of preformed parts , e.g. welding of plastics materials; Apparatus therefor general aspects of processes or apparatus for joining preformed parts B29C66/00; using porous material formed by internal pressure generated therein for joining preformed parts B29C44/1228, B29C44/326
• CPC Class Codes: B29C 65/561 using screw-threads being integral at least to one of the parts to be joined
• CPC Class Codes: B29C 65/58 Snap connection
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/1142 Single butt to butt joints
• CPC Class Codes: B29C 66/128 Stepped joint cross-sections
• CPC Class Codes: B29C 66/1282 comprising at least one overlap joint-segment
• CPC Class Codes: B29C 66/12841 comprising at least two butt joint-segments
• CPC Class Codes: B29C 66/54 Joining several hollow-preforms, e.g. half-shells, to form hollow articles, e.g. for making balls, containers; Joining several hollow-preforms, e.g. half-cylinders, to form tubular articles
• CPC Class Codes: B29C 66/543 joining more than two hollow-preforms to form said hollow articles
• CPC Class Codes: B29C 66/5432 joining hollow covers and hollow bottoms to open ends of container bodies
• CPC Class Codes: B29C 66/55 sealing elements being incorporated into the joints, e.g. gaskets B29C66/52296 takes precedence
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/8322 Joining or pressing tools reciprocating along one axis
• CPC Class Codes: B29K 2023/12 PP, i.e. polypropylene
• CPC Class Codes: B29K 2069/00 Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2077/00 Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2079/085 Thermoplastic polyimides, e.g. polyesterimides, PEI, i.e. polyetherimides, or polyamideimides; Derivatives thereof
• CPC Class Codes: B29K 2081/04 Polysulfides, e.g. PPS, i.e. polyphenylene sulfide or derivatives thereof
• CPC Class Codes: B29K 2081/06 PSU, i.e. polysulfones; PES, i.e. polyethersulfones or derivatives thereof
• CPC Class Codes: B29L 2024/00 : Articles with hollow walls
• CPC Class Codes: B29L 2024/006 : multi-channelled
• CPC Class Codes: B29L 2031/7126 : large, e.g. for bulk storage
• CPC Class Codes: B29L 2031/7156 : Pressure vessels
• CPC Class Codes: F24H 1/181 : Construction of the tank
• CPC Class Codes: F24H 1/182 : Insulation

Abstract

An electric water heater has a body structure formed in a manner eliminating the need for a separate metal water storage tank therein. The body structure is formed from a coaxially and sealingly joined series of one-piece molded plastic body sections including opposite end sections having closed outer ends. Each one piece molded plastic body section has tubular inner and outer shell portions that are coaxial with one another and radially separated by a circumferentially spaced series of radially extending ribs molded integrally therewith and defining therebetween a circumferentially extending series of arcuate insulation spaces. In the assembled body structure the inner shell portions entirely define in the water heater an internal water storage vessel portion that is outwardly enveloped by the insulation spaces and structurally reinforced, via the integral ribs, by the outer shell sections. Suitable inlet and outlet piping is operatively communicated with the interior of the body structure, and water disposed in the internal storage vessel portion thereof may be selectively heated by one or more electric resistance type heating elements operatively mounted on the water heater body structure.

Claims

1. Water storage apparatus comprising:

a plurality of molded plastic one piece hollow tubular body sections positioned in a coaxial, end-to-end orientation in which there is at least one axially adjacent pair of body sections, and including first and second opposite end sections having closed outer ends, each of said body sections having at least one open end portion and further having;

(1) a tubular inner shell section,

(2) a tubular outer shell section coaxially circumscribing said tubular inner shell section and forming between said inner and outer shell sections an annular insulation space, and

(3) a circumferentially spaced series of ribs extending radially across said annular insulation space and dividing said annular insulation space into circumferential segments, said ribs being integrally molded with said inner and outer shell sections, and said closed outer ends of said first and second opposite end sections being integrally molded with said first and second opposite end sections; and

joining means for permanently and sealingly joining opposing contiguous open end portions of each axially adjacent pair of said plurality of body sections in a manner forming from said plurality of body sections a hollow water storage body structure having an internal water storage vessel portion defined entirely by said inner shell sections, outwardly enveloped by said annular insulation spaces and structurally reinforced, via said ribs, by said outer shell sections.

2. The water storage apparatus of claim 1 wherein:

said plurality of body sections includes only said first and second opposite end sections.

3. The water storage apparatus of claim 1 wherein:

said plurality of body sections includes said first and second opposite end sections and at least one additional body section coaxially interposed between said first and second opposite end sections.

4. The water storage apparatus of claim 1 wherein said joining means include:

an induction weld at the opposing open end portions of each axially adjacent pair of said plurality of body sections.

5. The water storage apparatus of claim 1 wherein:

said annular insulation space segments are empty.

6. The water storage apparatus of claim 1 wherein:

said annular insulation space segments are filled with a thermal insulation material.

7. The water storage apparatus of claim 1 wherein:

said plurality of body sections are of a reinforced polypropylene-based plastic material.

8. The water storage apparatus of claim 1 wherein:

said plurality of body sections are structural foam plastic moldings.

9. The water storage apparatus of claim 1 wherein:

each axially facing pair of open end portions of said plurality of body sections have annular, interlocked axially notched portions.

10. The water storage apparatus of claim 1 in which said water storage apparatus is a water heater and further comprises:

supply means for flowing water to be heated from an external source into the interior of said internal water storage vessel portion,

heating means operative to heat water disposed within said internal water storage vessel portion, and

outlet means for discharging heated water from said internal water storage vessel portion of said hollow water storage body structure.

11. The water heater of claim 10 wherein said heating means include:

at least one electric resistance type heating element extending into said internal water storage vessel portion of said body structure.

12. A method of fabricating water storage apparatus comprising the steps of:

providing a plurality of molded plastic one piece hollow tubular body sections including first and second opposite end sections having a closed outer end, each of said body sections having at least one open end portion and further having a tubular inner shell section, a tubular outer shell section coaxially circumscribing said tubular inner shell section and forming between said inner and outer shell sections an annular insulation space, and a circumferentially spaced series of ribs extending radially across said annular insulation space and dividing said annular insulation space into circumferential segments, said ribs being integrally molded with said inner and outer shell sections, and said closed outer ends of said first and second opposite end sections being integrally molded with said first and second opposite end sections;

positioning said plurality of body sections in a coaxial, end-to-end array, in which there is at least one axially adjacent pair of body sections, with said closed outer ends of said end sections facing axially outwardly at opposite ends of said array; and

permanently and sealingly joining opposing contiguous open end portions of each axially adjacent pair of said plurality of body sections to form from said plurality of body sections a hollow water storage body structure having an internal water storage vessel portion defined entirely by said inner shell sections, outwardly enveloped by said annular insulation spaces and structurally reinforced, via said ribs, by said outer shell sections.

13. The method of claim 12 wherein:

said providing step is performed by providing only said first and second opposite end sections.

14. The method of claim 12 wherein:

said providing step is performed by providing said first and second opposite end sections and at least one additional body section coaxially interposable therebetween.

15. The method of claim 12 wherein:

said joining step includes the step of induction welding opposing open end portions of each axially adjacent pair of said plurality of body sections.

16. The method of claim 12 wherein said joining step includes the steps of:

forming annular, axially inwardly extending notches in each axially facing pair of open end portions of said plurality of body sections, and

axially interlocking each facing pair of said open end portions using said notches therein.

17. The method of claim 12 further comprising the step of:

filling said annular insulation space segments with a thermal insulation material.

18. The method of claim 12 wherein:

said providing step is performed by molding said plurality of body sections from a reinforced polypropylene-based plastic material.

19. The method of claim 12 wherein:

said providing step includes the step of forming said plurality of body sections using a structural foam plastic molding process.

20. The method of claim 12 further comprising the steps of:

providing supply means for flowing water to be heated from an external source into the interior of said internal water storage vessel portion,

operatively extending at least one electric resistance type water heating element into said internal water storage vessel portion of said body structure, and

providing outlet means for discharging heated water from said internal water storage vessel portion of said body structure.