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Патент USA US2403895

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` MÃ? Ey 346»
c. F. ALBAN ETAL
2,403,895
THERMOSTATIC METAL
Filed Feb. 2s, 1942
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July 16, 1946.
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c. F. ALBAN ErAL `
THERMOSTATIC
2,403,895
METAL
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Filed Feb. 2a; 1942
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Patented July 16, 1946
2,403,895
UNITED STATES PATENT «oF-FICE
‘THERMOstroîrîîîiivnrrsi.l
l
l
l
Clarence F. Alban, Pontiac, and Stanley R. Hood,
Birmingham, `Mich., assignors to W. M. Chace
Company,
Michigan
Detroit, Mich., `a 'corporation ` of
Application February 28, 1942, Serial No. 432,832
2 Claims. (Cl. 297-15)
l
2
This invention relates to thermostatic metal.
'I‘his application is a continuation-impart of our
static metal, such as a Vhigh melting point, a
high coefficient of expansion 4and high strength
at high temperatures, but since manganese Ais
brittle it alone cannot be used for `the high ex
panding lamina of thermostatic metal. Because
of `this manganese is alloyed with copper which
produces a ductile alloy having a high melting
application Serial No. 315,130, iiled January 22,
1940, now abandoned.
Itis a common expedient in temperature re
sponsive mechanisms and controls to utilize the
diiference in expansion of two metals or alloys
point, high strength at high temperatures and
to effect mechanical movement. The mechanical
a remarkably vhigher coeiiicient of expansion than
movement is usually vobtained by usingïone metal
having a vhigh> coeirìcient of expansion and an l0 either Vpure manganese or copper and a remark
ably higher electrical resistivity.
other metal having a low coeliicient of expansion
According to Mechanical Engineers’ Handbook
which are either Ífused together to form thermo
by -Lionel S. Marks, fourth edition, 1941, page
static bimetal or mechanically arranged as, for
624, manganese has a linear coeiiicient of ther
example, a rod within a tube. The degree of
movement obtained and the amount of work 16 mal expansion per degree F. at about ’70° F. of
produced depends in general on three factors:
12.8 >< 10-5,‘nickel 7.2><1'0T6, and copper 9.12X'l0rï6.
This remarkable increase .in -thermal expansion
the strength of the materials used, the temper
of the Aalloy in contrast to manganese is »remark
alture chang , and the difference in expansion
ably demonstrated, `by way of example, if one
coefficients of the two metals.
considers the coeflicient of expansion of an alloy
The following metals and alloys having high
consisting of 72% manganese, 18% copper, and
coefficients ofi-expansion are commonly used in
10% nickel. According >to the law of mixtures,
temperature responsive mechanisms and con
one would expect a low linear coefficient of ex
trols: copper, brass (60% copper, 40% zinc) and
pansion for‘this alloy 0f 11.57 >< 10-6 per degree F.
iron-nickel alloys to` which may be added chro
at about '70° F. Actually one gets the remark
mium, for example, .an alloy containing 22%
ably high linear coefficient `of expansion of
l5.5><l0”6. Because of this property of the
manganese alloy, the thermostatic metal, which
is the subject of this invention, Vhas a remarkably
nickel, 3% chromium, 75% iron. Upto the pres
ent no alloy >has ben developed which has both
an expansionrate higher than a 60-40` brass and
good strength‘characteristics at temperatures as
high deflection rate.
In fabricating the high expanding lamina the
best analysis having the highest strength, high
50% 'nickel are commonly used. Invar (36%
est expansion rate and highest .electrical `resist
nickel, 64% iron) is one such alloy commonly
ivity is a ternary alloy consisting of ‘72% Aman
used for the low expansive element. The low
expansive element `can also be made from an 35 ganese, 18% copper and 10% nickel. Although
the above is the preferred analysis, other excel
alloy of 17% chromium, `4% aluminum, balance
high as 500° »C.
For a` low expansive element
iron-nickel alloys containing between 35% and
lent alloys can be obtained for use as the high
expanding lamina wherein the manganese ranges
iron.
It is an object of this invention toproduce a
laminated thermostatic metal which has a higher
electrical -resistivity and which will produce -a
from `60% to 85% of theal‘loy by weight, `wherein
the copper >ranges from 10% to `35% by weight of
the alloy, and wherein the nickel ranges -from
5% to 30% by weight oi the -alloy. yAlthough the
remarkably lhigher strain energy per degree tem
perature difference than any other known ther
mosta'tic metal.
above are the preferred ranges Yof the constitu
ents of the alloy, ‘these ranges can be widened
.
This invention also contemplates a laminated
thermostatic »metal having an appreciably higher
deilection rate than any other known thermo
Vstatic metal.
jThis object has been vachieved by utilizing a
4.5
somewhat to include other analyses which pro
duce a material much 'better suited as vthe
high expanding lamina , of thermostatic `metal
than other known materials.
In this enlarged
range the constituents by weight would comprise
nary alloy of manganese, copper and‘one o-f the 5,0 the 'following percentages of the alloy: mangan
ese 15% t0 95%, copper 85% to 5%, nickel 0% to
iron group metals, as the high expanding lamina
of the thermostatic metal. >Manganese, both
30%. Cobalt or iron can be substituted Wholly
or in part for .nickel 1in the ranges above speci
commercially pure .manganese and electrolytic
lied. However, nickel is preferred over either
manganese, has properties which make it desir
cobalt or iron. Nickel when alloyed with copper
able as the high expanding lamina of thermo
binary yalloy of manganese and copper or a ter
3
4
One of the best thermostatic bimetals available
and manganese raises the elastic limit of the al
loy and improves the physical properties in gen
eral of the alloy. The nickel also gives the alloy
stability, that is, causes the alloy upon cooling
on the market is known as Chace #2400. The
Chace #2400 bimetal has a low side of Invar
(36% nickel, balance iron) and a high expand
to travel along the same curve that it traverses 5 ing side of 22% nickel, 3% chromium, balance
While being heated. In other Words, nickel
iron by weight. It is interesting to compare the
causes the alloy when its expansion and contrac'2400 thermostatic bimetal with the herein pre
tion characteristics, due to thermal change, are
ierred bimetal; namely, that having a low ex
plotted on a graph, to travel along the same
panding lamina of Invar and a high expanding
curve upon a fall in temperature that it trav‘- 10 lamina of 72% manganese, 18% Copper, 10%
eled upon a corresponding rise in temperature.
Y nickel by weight. A very careful and exhaustive
Manganese having a purity of 99.98% can be
study of these two bizmetals has been made which
produced electrolytically. So-called commershows that the thermostatic metal, which is the
cially pure manganese usually contains about 3%
subject of this invention, is surprisingly superior
to 5% of impurities, such as iron, carbon, alu- 15 to the best of the known bimetals.
minum and silicon. In the above analyses it is
of this study is set forth below:
preferred to use electrolytically pure manganese
»
throughout the entire range. However, commer-
'
'
Advantage-gained through use
cially -pure manganese -can be used up to a point
of?? Mn, tig?, ciät a12% gril
at which the commercially pure manganese ap- 2o
ätafäggïïrgloääìrmggtauc
proximates about 35% of the alloy.
bimetal
Where the
manganese comprises more than 35% of the alloy,
Y
y
3.
orX10-t
«X10-o
~
„X10-a
50%
constant temperature difference:
Ident‘calslz‘e'
Constant temperature diñerence:
' Ident‘calwe‘ght'
Constant electrical current: Identi
Temperature rlse
cel size.
156%
Constant eletrical current: Identi
_
170%
5. Strain energy
Constant electrical current: Identi
cal welght.
4. Strain energy
Ni, balance
Cu
f
anne” “Se
f
amounts of manganese over about 35% of the
1' Smm energy
alloy should be electrolytically pure manganese. 25
' ,
58%
The following expansion data is characteristic
2' Smm energy
Of the ÍOHOWÍIlg allOYSZ
~
30%.
„X10-e
M
' ` _
then to avoid brittleness it is essential that all
Tânèp" 23% Mn,4% 27% Mn, 4% 32% Mn, 5% 9% Mn,5%
A summary
30
cal slze.
_
_
Fe, balance
Cu
Fe, bsleuee
Cu
Ni, 5% Fey
balance Cu
3002221:
22Í4
2310
2413
2dr 35 ing thermal deilection of the rbimetal and is the
400 ----- --
23'4
23-9
25-2
22-2
----- --
Strain energy is the force developed by restrain
Expansion data and representative resistance
data is herewith set forth of the below specified
alloys:
`
Temperature range .Resistance
Alloy
ägzfägâsiggegflâë;
em.per degree C.
measure of the work which the bimetal cando.
TheV above summary showsk (1) On the basis of
a given temperature difference for pieces of the
same size, the ratio of the strain energy avail
40 able through the use of the new manganese ther
mostatic bimetal and the 2400 bimetal is 1.5 to 1;
(2) This relationship, as mentioned immediately
above in paragraph (l), for pieces of the same
foot at 20° C.
Weight of the new manganese thermostatic bi
45 meta1 and the 2400 bimetal is 1.58 to l. (3)
QSXHH
900
The
fact that the electrical resistivity of the new ma
terial is considerably higher than that of the older
28X1Ü'“
sexie-ß
,IOXMH
11140
#2400 results in an added advantage in those
1,140
cases »where the temperature change is accom
950 50 plished from the passage of electric current. The
ratio of the temperature diiïerentials of pieces of
38X10'”
mms, at 20° Q_
780
1,200
the same size of several materials when heated
by the passage of the same quantity of electric
`current will, in the general case where tempera
55 ture difference 1s a linear function of heat input,
The above described binary and ternary alleysa
due t0 their high coefficient 0f expansion and
high electrical resistance are Very useful in the
fabrication of thermostatic metals, particularly
be proportional to the ratio of the electrical re
SiStiVity for the materials in question. It ÍOllOWS
then that-the ratio of the temperature rise of the
new thermo-static bimetal '00 the #2400, when
those thermostatic metals such as bimetal, tri- 60 pieces 0f the Same Size are heated by the passage
mel-,el and other plural laminae thermostatie
of equal amounts of electric current is 1.308 to l.
metals. In the fabrication of such thermostatic
(4) The raf/i0 0f Strain energy 01‘ WOrk resulting
metals a lamina of the above manganese alloy is
from the passage 0f equal amounts 0f electric
fused or Otherwise bonded to a lamine, of a
current through pieces of the same size of the new
metal 0r- alloy having a, 10W coeñlcient of expam 65 manganese Inval' thermostatic bimetal and the
Sion Such as Invar or nickel_ìr0n alloys contain_
#2400 bimetal is 2.566 to l. (5) The relationship
ing between 35% and 50% nickel. If desired, the
mentioned directly above in paragraph (4) for
low expansion lamine, een be made from e, ter-
pieces of the new manganese Invar thermostatic
nary alley of iron, nickel and titanium In such
bimetal and the #2400 bimetal of identical Weight
case> thenickel content will range from 35% to 70 iS 2~70 t0 1-
50%, lelle titanium content from 1% to 4%J kand
the remainder iron" The preferred jr0n_nicke1_
titanium alloy for the low side contains from 35%
to 42% nickel, about 2.5% titanium, and the
remainder iron.
‘
'
In the above described bimetal the difference
between the COemCÍeIlÈS Of eXpal’lSÍOIl Of‘ the high
and 10W 'eXpal'ldîng lamina@ iS greater than in
_ those bimetals heretofore known. , The advan
75 tages of increasing the diiïerence in the expansion
2,4o3,895
5
rates of the two laminae are evident,
6
For ex
ample, where such bimetal is used in temperature
a water heater, the burner of which is controlled
by a tube and rod type thermostat.
The gas supply is admitted through pipe I into
valve chamber 2 and passes through pipe 3 into
the burner (not shown). The valve housing 2
responsive mechanisms and controls, for a given
size of control element the deflection or strength
of the element is increased compared with )a con
trol element of other known bimetals of such given
is provided with a valve 4 pivoted as at 5 and
size, thus making the instrument or device in
backed up by a compression spring E which tends
which it is used more positive or sensitive. Fur
at all times to hold valve 4 in the closed position
ther, because of the high deñection rate and
shown, thereby cutting off the ñow of gas through
strength of such bimetal, where a given combina 10 pipe 3 to the burner. The hot Water tank is des
ignated 1.
tion of strength and deñection is needed in a
control element, smaller amounts can be used
Valve 4 is controlled by a thermostat in the
than is possible where the control element is made
form of a tube 8 secured to the tank 1 as at 9 and
from other known bimetals, thus effecting a sav
a rod I0 mounted within the tube 8 and contact
ing in the cost of the control element. Since this 15 ing the tube 8 at Il. Tube 8 is made of the above
high electrical resistance bimetal has a higher
described high expansion alloy of manganese,
deñection rate than any other known bimetal, it
copper and nickel. The rod I0 can be any suit
lends itself to great utility in the manufacture
low expansion alloy such as Invar. In the posi
of low amperage circuit breakers.
tion shown, the water in the tank is at the ele
'I‘he thermostatic laminated metal which is the 20 vated temperature desired. As the temperature
subject matter of this invention gives a greater
of the water in the tank 1 falls, tube 8 will con
work output for a given electrical input than those
tract thereby raising rod l0 which swings valve 4
thermostatic laminated metals heretofore known.
about its pivot 5 thereby opening valve 4 and
This is important, particularly in electrical devices
permitting gas to flow through line 3 to the heater.
where the electrical resistance of the thermostatic
As the temperature of the water rises, rod 8 will
metal element is important. In such an electrical
expand thereby lowering rod I0 which permits
device Where a thermostatic element having a
spring 6 to close valve 4 and thereby stop the
given electrical resistance and deflection is de
iiow of gas through line 3 to the heater.
sired, it is necessary to use a relatively small piece
We claim:
of the heretofore known thermostatic metals. 30
1. Thermostatic metal comprising a plurality
This was disadvantageous because such a small
of joined metallic laminations, one of said lam
piece of thermostatic metal gave correspondingly
inations having _a relatively high coeiîcient of ex
small power. On the other hand in such an elec
pansion and comprising an alloy of the following
trical device, due to the high electrical resistance
constituents by weight: manganese from 20% up
of the instant thermostatic metal, to satisfy such 35 to 50%, nickel 4% to 20%, balance substantially
given electrical resistance and deflection a piece
all copper; the other lamination having a rela
of the instant thermostatic metal can be used
tively low coefñcient of expansion.
which is larger than the usable ‘piece of hereto
2. In a device responsive to temperature
fore known thermostatic metals. Due to the fact
changes to perform work or mechanical move
that a relatively larger- piece of the instant ther 40 ment, a plurality of metallic members, one of said
mostatic metal can be used, such piece of ther
members having a relatively high linear coefficient
mostatic metal will give more power.
of thermal expansion and comprising analloy of
In the drawings:
the following constituents by weight: manganese
Fig. 1 shows the temperature expansion coeiii
from 20% to 50%, nickel 4% to 20%, balance sub
cient data of two copper-manganese alloys com 45 stantially all copper; the other member having a
pared with standard materials.
relatively low linear coefficient of thermal ex
Fig. 2 shows a bimetal strip having a high ex
pansion and comprising essentially “Invar,” an
panding lamina of manganese, copper and nickel
alloy of iron and nickel.
and a low expanding lamina of Invar. The two
50
laminae are welded together.
CLARENCE F. ALBAN.
Fig. 3 is an illustrative showing of a portion of
STANLEY R. HOOD.
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