RESISTORED SACRIFICIAL ANODE ASSEMBLY FOR METAL TANK

ANODE SACRIFICIELLE AVEC RESISTANCE POUR RESERVOIR METALLIQUE

English Abstract

A sacrificial anode assembly is insertable into a metal water storage tank to inhibit corrosion thereof and includes a cylindrical metal anode member having an end retained within a cylindrical plastic insulating sleeve which, in turn, is captively retained within a metal cap portion of the assembly. To regulate the amount of electrical current generated by the assembly during use thereof, a barrel-shaped resistor is supported within the assembly and interconnected between its anode and cap portions. The insulating sleeve has a generally U-shaped groove formed in a closed end thereof, with one leg of the groove extending diametrically across a central opening in the sleeve end that receives a core wire portion of the anode member, and the other groove leg extending generally chordwise relative to the sleeve end. The resistor body is received within the chordwise groove leg, and a lead wire of the resistor is extended through the curved and diametrically extending groove portions and spot welded to the core wire portion received in the central sleeve end opening. The configuration of the groove and the relative orientation of the resistor and sleeve opening causes the bent lead wire to form a resilient connection between the spot weld and the resistor body, thereby substantially reducing vibrational fatigue stress on the spot weld during shipping and handling of a tank having the anode assembly operatively installed thereon.

French Abstract

Une anode sacrificielle peut être insérée dans une citerne d'eau métallique afin d'en inhiber la corrosion : elle est composée d'une anode métallique cylindrique dont un bout est fixé dans une gaine isolante en matière plastique qui est, à son tour, retenue de façon captive dans un chapeau métallique de l'ensemble. Afin d'assurer la régulation de la quantité de courant électrique produite par l'ensemble au cours de son utilisation, une résistance en forme de barillet est supportée dans l'ensemble, et interconnectée entre son anode et son chapeau. La gaine isolante présente une cannelure à forme générale de U, formée dans une extrémité fermée, une jambe de la cannelure s'étendant diamétralement à travers une ouverture centrale dans le bout de la gaine s'étendant d'une manière générale sur sa corde par rapport à l'extrémité de la gaine. Le corps de la résistance est reçu dans la jambe à cannelure dans la corde, et un fil conducteur de la résistance s'étend à travers les parties de cannelures courbes et à direction diamétrale, et est soudé par points sur la partie du câble central, qui se place dans l'ouverture au bout de la gaine centrale. Sous l'effet de la configuration de la cannelure et de l'orientation relative de la résistance et de l'ouverture de la gaine, le fil conducteur plié forme une connexion flexible entre la soudure par points et le corps de la résistance, en réduisant ainsi considérablement la contrainte de fatigue vibratoire sur la soudure par points au cours de l'expédition et de la manutention d'une citerne sur laquelle on installe l'anode.

Claims

The embodiments of the invention in which an
exclusive property or privilege is claimed are defined
as follows:
1. A water heater comprising:
a metal tank adapted to hold a quantity of
water to be heated, and a sacrificial anode assembly
supported on said metal tank, said sacrificial anode
assembly including:
an elongated metal anode member extending
into the interior of said metal tank, said anode member
having a core wire extending axially therethrough and
projecting outwardly through an end of said anode
member,
an insulating sleeve member receiving and
being captively retained on said end of said anode
member, said insulating sleeve member having:
an end wall portion with a central opening
that receives an end portion of said core wire,
a first exterior surface groove formed in
said end wall portion and having a first generally
straight section extending into said central opening
and having an end spaced apart form therefrom, a second
generally straight section offset from said first
section and having an end spaced apart from said
central opening, and a curved third section joining
said ends of said first and second sections, and
a second exterior surface groove formed in
and extending generally axially along a side wall
portion of said insulating sleeve member, said second
exterior surface groove defining a continuation of said
second section of said first exterior surface groove;
a hollow metal cap member receiving and
captively retained on said insulating sleeve member,
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said cap member being secured to said metal tank; and
an electrical resistor having:
cylindrical body portion received in said
second section of said first exterior surface groove in
a spaced apart relationship with said end thereof,
a first electrical lead wire extending from
one end of said resistor body portion sequentially
through a portion of said second groove section, said
curved third groove section, said first groove section,
and across said central opening, said first electrical
lead wire having an outer end portion fixedly and
conductively secured to said end portion of said core
wire, and
a second electrical lead wire extending from
the opposite end of said resistor body portion and
through said second exterior surface groove, said
second electrical lead wire having an outer end fixedly
and conductively secured to said metal cap member.
2. The water heater of Claim 1 wherein:
said first groove section has a laterally
enlarged portion that receives said resistor body
portion and is configured to essentially prevent
movement thereof relative to said insulating sleeve
member.
3. The water heater of Claim 1 wherein:
said outer end portion of said first lead
wire is spot welded to said end portion of said core
wire.
4. The water heater of Claim 1 wherein:
said insulating sleeve member has a generally
cylindrical configuration,
said first groove section extends generally
diametrically across said end wall portion of said
insulating sleeve member, and
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said second groove section extends generally
chordwise across said end wall portion of said
insulating sleeve member.
5. The water heater of Claim 1 wherein:
said insulating sleeve member is molded from
a plastic material.
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Description

` 217~5~ -
Docket No .: RHWH- 0 0 1 9
RESISTORED SACRIFICIAL ANODE: A~ ~ PMRT-Y FOR M13TA1 TANK
RACT~I'.RI I OF T~E INVE NTION
The present invention relates generally to anode devices used
to inhibit corrosion in metal water heater tanks and other metal
5 liquid storage vessels and, in a preferred embodiment thereof, more
particularly relates to a specially designed resistored anode
assembly useful in this corrosion-inhibiting application.
Conventional metal water heater tanks, like other types oE
metal vessels used to store liquids, are subject to corrosion
10 durin~ use. To inhibit this corrosion, sacrificial anodes,
normally constructed of magnesium, aluminum or zinc, are inserted
into the tank. The sacrificial anode is slowly cu.~ during the
corrosion protection process while generating an electrical
current. As the anode is slowly depleted, it~: simultaneously
15 generated electrical current cathodically protects the ~ank against
corrosion .
The service life of the anode tends to be inversely dependent
upon the amount of electrical current it generates in cathodically
protecting the tank. In many fresh water supplies, particularly
20 those having a hLgh mineral content, the current flow generated by
the anode ls relatively high, resulting in a corresponding decrease
in the useful life of the anode. In order to control the rate of
uc,~ u.~.~Lion of a sacrificial anode, various anode ~ u~Lions

~ 2178511
have been proposed in which a resistor is inuuL~ ted in the
anode, and electrically connected between the anode and its
protected tank, to automatically regulate the electrlcal ourrent
generated by the anode during its operation and thereby increa~;e
5 the 6ervice lif e of the anode .
While these resistored anode devices typically extended anode
life, many of them also tended to be of a relativ~ely complex
construction, rather difficult to assemble, and relatively
expensLve to fabricate.
Many of these problems are essentially eliminated by a prior
art sacrificial anode assembly that in~.L~o-~es, in a simplified
manner, an ordinary barrel-type carbon resistor into the interior
of the assembly. This prior art anode assembly include6 a
cylindrlcal plastic insulating sleeve captively retained within the
metal cap portion of the anode assembly and having a closed end
with a central opening through which an end portion of the metal
anode body core rod extends. A diametrically extending groove,
which intersects the central sleeve opening~ is formed in the
closed sleeve end.
The cylindrical resistor body is disposed in a radial portion
of the sleeve end groove, with one of the resis~or end leads being
radially extended over the anode rod end and soldered thereto. The
other resistor end lead passes through an axially extending
exterior side surface groove in the insulating sleeve and is
soldered at its outer end to an external metal cap portion of the
anode assembly.

- ~ 2~
Although this method of operatively positioning a resistor in
a sacrif icial anode assembly provides a worthwhile reduction in
assembly time and cost, and provides the desired regulation of
anode current generation, it has been found that it can create a
problem relating to the tjL~u~:LuLal integrity of the completed anode
assembly. Specifically, it has been found that in certain shipping
orientations of the tank in which the anode assembly L8 installed,
harmonic vibrations may be created within the central anode core
rod which are transmitted to the solder ~oint connectillg a resistor
end lead to the rod. These vibrations can fatigue and break the
rod/lead solder ~oint, thereby rendering the anode assembly
inoperative . .
From the foregoing it can be seen that it would be desirable
to provide a sacrificial anode assembly, of the type having an
insuiating sleeve-installed resistor as generally described above,
which substantially eliminates this vibration-caused solder ~oint
breakage problem. It is accordingly an ob~ect of the present
invention to provide such a sacrificial anode assembly.
SUM~ARY OF THE lrlV~nlll
In carrying out principles of the present invention, in
accordance with a preferred ~ L thereof, a specially
designed resistored sacrificial anode assembly is provided for use
in a metal liquid storage to inhibit vessel corrosion
The anode assembly may be secured to the vessel, to extend
into its liquid filled interior, and ~ ncll~A~ an elongated metal
anode member having a core wire extending longitl~in~l~y
--3--
. .

` ~ 21~85~1
therethrough and pro~ecting outwardly through an end thereof. An
insulating sleeve mem~er, preferably formed from a molded plastic
material, receives and is captively retained on this anode member
end and has an ond wall portlon with a central opening therein that
5 receives an end portion of the core wire. A hollcw metal cap
member received and is captively retained on the insulatLng sleeve
member .
An electrical resistor is ~ po~d within the cap member and
has a cylindrical body portion with first and Gecond ends. First
10 and second electrical lead wires respectively extend outwardly from
the first and second resistor body ends.
Exterior surface groove means are formed in the end wall
portion of the insulating sleeve member and receive the resistor
body in a manner positioning its length perpendicular to the
15 longftudinal axis of the insulating sleeve. These groove means
have a curved portion through which the first electrical lead wire
extends to the core wire end portion, the groove means being
configured to permit lateral ~. t of the first electrical lead
wire therein. Means, representatively in the form of a spot weld,
20 are provided for fixedly and conductively securing an outer end
portion of the f irst electrical lead wire to the core wire end
portion .
Because of the unique conf iguration of the groove means, the
bent first electrical lead wire received therei~ forms a
25 resiliently deflectable interconnection between the spot weld and
the resistor body. Accordingly, late~al vibrational forces created
.
' .",
. ': `

` ~ 2~785~1 ;
in the core ~ire (arising, for example, during shipping and
handling of the vessel within which the anode assembly is
,L~.Led) are not rigidly resisted by the first electrical lead
wire. Instead, the bent first electrical lead wire is causea to
laterally flex within the groove means in response to lateral
vibrational 1 ~Vl t of the core wire end portion, thereby
protecting the lead wire/core wire spot weld against fatigue stress
breakage .
Means are also provided for fixedly and conductiv~ly securing
an outer end portion of the second electrical lead wire to the
metal cap member. In a preferred form thereof, these means include
an exterior side surface groove formed on the insulating sleeve and
receiving the second resistor electrical lead member, and a spot
weld securing an outer end portion of the second lead member to an
open end portion of the cap member.
BRIE F DES~:K~ OF ~IE DRAWINGS
FIG. 1 is a schematic partial cross-sectional view through a
representative metal water heater tank having operatively installed
on a top end thereof a resistored sacrificial anode assembly
embodying princlples of the present invention;
FIG. 2 is an enlarged scale partial cross-sectional view
through the anode assembly taken along line 2-2 of FIG. 1;
FIG. 3 is a cross-sectional view through the anode assembly
taken along line 3-3 of FIG. 2; and
FIG. 4 is a perspective view of an internal plastic insulating
sleeve portion of the anode assembly.
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, ;' '

-~i 2~78~
I~TATT T~n DE SCRIPTION
Ref erring to FIGS . 1-4, the present invention provides a
specially designed resi6tored sacrificial anode assenbly 10 which
is operatively installed in the top end wall 12a of a
representative metal water heater storage tank 12, extends into the
water-filled interior of the tank, and operates to cathodically
inhibit corrosion of the tank. As cross-sectionally i~lustrated ln
FIG. 2, the anode assembly 10 includes a cylindrically shaped
sacrificial anode member 14 having a main body portion 16, a
reduced diameter neck portion 18 having an annular F-ytc.rn~l side
surface indentation 20 formed therein, and an annu~ar ledge 22
formed at the ~uncture of the main body and neck portions 16,18.
Axially extending centrally through the anode member 14 is a metal
core wire or rod 24 having an upper end portion 24a extending
upwardly beyond the upper end of the neck portion 18.
The anode member neck portion 18 is coaxially pressed into the
open lower end 26 of a cylindrical, molded plastic insulating
sleeve 28 having a closed top end 30 through which a central
circular hole 32 is formed. When the anode neck 18 is pressed into
sleeve 28, the wire end portion 24a is received in the hole 32.
Sleeve 28, in turn, is pressed into a hollow cylindrical metal
cap mem~er 36 having an enlarged diameter head portion 38, and a
hollow externally threaded body portion 40 threaded ~nto the top
tank end wall 12a as shown in FIG. 2. A lower end portion 40a of
the body portion 40 is inwardly swaged against the body of the
plastic sleeve 28 to captively retain the sleeve 28 within the cap
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" ' .

- 2~7~51 1 I
member body 40. This swaging also forces an annular portion 34 of
the sleeve 28 lnto the annular groove 20.
To control and maintain the protective anode current at a
suitable level, the anode assembly 10 is provided wiLth a barrel-
shaped resi6tor 42 (see FIGS. 3 and 4) having metal lead wires 44
and 46 extending outwardly from its opposite ends. To support the
re~iistor 42 on the top end of the sleeve 28, a specially configured
exterior surface groove 48 is formed in the sleeve. As best
illustrated in FIGS. 3 and 4, the groove 48 has a portion 48a
extending diametrically across the closed top sleeve end 30 from
opposite sides of the circular sleeve opening 32: a portion 48b
extending generally chordwise across the sleeve end 30 and having
a Lr Illt~V~L~ely enlarged portion 48c; a curved portion 48d joining
ad~acent left ends of portions 48a and 48b: and a portion 48e
extending axially along the external side surface of the sleeve 28
from the right end of the groove portion 48b.
Accordingly, the exterior groove 48 sequentially extends
upwardly along the body of the sleeve, across the top end of the
sleeve in a chordwise direction, bends around at groove portion
48d, and then extends diametrically across the top sleeve end
opening 32. The chordwise groove portion 48c is representatively
illustrated as being parallel to the diametrically extending groove
portion 48a. However, groove portion 48c could be oriented at an
angle to groove portion 48a if desired.
zs The groove portions 44a-44c on the top end of tihe sleeve 28
are vertically deeper than the resistor 42 (see FIG. 2), all of the
. .

2 1 7 8 ~ 1 l ' `
groove portions 44a-44e are laterally wider than the resistor leads
44 and 46, and the horizontal width and length of the laterally
enlarged groove portion 48c are sized to permit the resistor 42 to
be snap-fitted into the groove portion 48c to inhibit movement of
the resistor relative to the groove portion 48c. Alternatively,
the groove portion 48c could be configured to permit at least
limited l v~ L of the resistor within the groove portion 48c.
Prior to the insertion of the sleeve 28 within the body
portion 40 of the cap member 36, the resistor 42 is snap-fitted
into the laterally enlarged groove portion 48c: the resistor lead
44 i8 extended along the groove portions 48b,48d and 48a and spot
welded to the core wire portion 24a as at 50 ~ see FIG. 3 ); and the
resistor lead wire 46 is extended downwardly through the vertical
groove portion 48e. After the anode member-supported sleeve 28 is
operatively inserted into the body of the cap member 36, the outer
end of the lead 46 is spot welded, as at 52 (6ee FIG. 2), to the
lower end of thc cap member body portion 40. ~he completed anode
assembly lO is then ready to be threaded into the tank wall 12a as
illustrated in FIG. 2.
In prior art anode insulating sleeves similar to sleeve 28,
the resistor is fixedly held in a diametrically extending groove
formed in the closed sleeve end. Using this conventional resistor
support configuration, the upper end of the anode care wire, and
thus the core wire/lead wire spot weld, is longit~ in~l~y aligned
with the cylindrical resistor body fixedly held on the closed
sleeve end. Accordingly, lateral vibrational movements of the core

217~5~1 f
wire are axially resisted by the resistor lead wire welded thereto
which, with respect to such lateral vibrational movements of the
core wire, forms an essentially rigid connection between the spot
weld and the f acing end of the resistor body . This essentially
5 rigid connection between the spot weld and the facing resistor body
end can fatigue and break the spot weld, the lead wire, or the
resistor body, thereby undesirably breaking the electrical current
path between the anode core wire and the metal anode cap.
In sharp contra6t, due to the unique conf iguration of the top
10 sleeve end portion of the groove 48 in the present invention, rigid
vibrational forces transmitted to the spot weld 50 (seQ FIG. 30)
from the core wire (arising, for example, when the tank 12 is
shipped in a horizontal orientation) are substantially eliminated.
This desirable result i5 achieved via the lateral shifting of the
15 resistor 42 out of axial alignment with the groove portion 48a, and
the generally ~-shaped configuration of the connected groove
portions 48a,48b,48d.
Specifically, it can be seen in FIGS. 3 and 4 that the spot
weld 50 is resiliently connected to the left end of the resistor 42
20 by the generally U-shaped lead wire 44 received in the connected
groove portions 48a,48b,48d. A vibrational shift of the spot weld
50 to the left as viewed in FIG. 3 is not met with a rigid lead
wire resistance. Instead, such leftward vibrational shift of the
spot weld 50 simply causes the bent portion of the lead wire 44 to
25 resiliently flex, and shift leftwardly within its groove portion
48d, without exerting an appreciable axial force on the resistor
.

2~7~511
42. In a similar manner, a vibrational shift of the spot weld 50
to the right is not met with a rigid lead wire resistance.
Instead, such rightward vibrational shift of the spot weld 50
simply causes the bent portion of the lead wire 44 to resiliently
5 flex, and shift rightwardly within its groove portion 48d, without
exerting an appreciable axial force on the resistor 42.
This resilient lead wire interconnection between the spot weld
50 and the resistor 42 thus advantageously functions to protect the
weld against vibrational fatigue breakage. ~he top sleeve end
10 groove modification embodied in the present invention may be easily
and ;n~ r~n~;vely inco~ ed into the anode assembly 10 to
appreciably increase both its durability and reliability.
The foregoing detailed description is to be clearly u~ld~l~,Lood
as being given by way of illustration and example only, the ~pirit
15 and scope of the present invention being limited solely by the
appended claims.
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.

Representative Drawing