close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2131065

код для вставки
27; 1938»
‘
2,131,065
A. OBERMAIER
- RESISTANCE THERIOHETER
Filed Aug. 24, 1934
2 Sheets-Shoot _1
INVENTOR.
J?kn d. 06ermazez'
BY
ATTORNEY.
Sept. 27, 1938.
‘J. A. OBERMAIER
). 2,131,065
RES I STANCE THERMOMETER
Filed Aug. 24, 1934
2 Shoots-Shoot 2
INVENTOR_. ‘
$1322 a. 'aéezwuwz'
a
‘
.
4a
683:
‘
I“
........ A
I
‘
BY‘
.
I
'M
.
r.
ATTORNEY.
Patented Sept. ‘27, 1938
2,131,065
UNITED STATES PATENT OFFICE
2,131,065
RESISTANCE THERMOMETER
John A. Obermaier, Chicago, Ill.
Application August 24,
1934, Serial No. 741,286
(01. 7s_ss2)
The joints between the ends of the thermal
resistance element and the lead wires that eX
tend the circuit to the terminals at the head of
the instrument are as close together as is rea
installation, ’
The thermal responsive element of the resist
ance thermometer of my present invention com
prises a resistance wire of suitable material and
10 size,
coiled to form a ?ne spring, and extended
_ through a series of longitudinal holes in a cylin
drical Piece of insulation. ‘The wire is within
the body of insulation, thus a?’ording protection
against damage. It is one of the objects of the
sonably possible. By reason of the closeness, the 5
two ends of the thermal resistance elements are
necessarily at the same temperature. This is of
importance where the lead wires are of a ma
terial different from that of the resistance ele
ment, as is generally the case, because a di?’eI- 1o
ence in temperature of the two joints at the ends
of the thermal'resistance element would result
in a thermo-electric current, as in a thermo
couple. This would seriously a?ect the accuracy
of the resistance-measuring bridge circuit by 15
which the temperature is determined. By plac
ing the two terminals of the thermal resistance
element very close together, this source
is eliminated. The connector terminals at the
head of the instrument are also placed close to- 20
gether for the same reason.
The resistance element is enclosed in a pro
solid material,
since air is a very good
The substance used should have
a high thermal conductivity and be a suiliciently
goodv electric insulator at the temperatures in
volved as not to affect the resistance of the.
coiled thermal resistance wire. Powdered alu
minum oxide or powdered magnesium oxide are
suitable for this purpose.
'
tective casing comprising a metal tube of suit
able length, the element being at one end of the
head of the thermometer is rather massive and
affords a large heat-radiating surface. The heat
loss may, in the absence of preventive
heat storage capacity,
tions, be such that there is an appreciable tem- 30
gradient along the tube so that the
time lag in the change in temperature of the
inner end of the tube, that is, the end where
the thermal resistance element is located, is not
'on the outside of the insulator changes. By
locating the wire-receiving holes close to the
periphery of the insulation this temperature lag
at the temperature of the surrounding medium.
The supporting insulator used has a certain
is made verysma . '
etemperature lag is fur
ther reduced by making the volume of the in
sulator as small as possible.
This is accom
plished by making the supporting insulator of
the
diameter that will permit the
formation of the requisite number of longitudi
nally—extending holes of the proper size and
spacing adjacent the periphery thereof.
circuit lead~in conductors, which serve also as
Supports for the cylinder of insulation, are an
chored in the Cylinder at the
thereof.
'
portion. By reducing the heat travel from the
tube to the head portion, the temperature gra
dient along the tube is reduced. The travel of
heat from the free end of the tube towards the
head portion may, in some instances, be entirely 45
eliminated by providing heat-absorbing ?ns on
the tube adjacent the head portion. These ?ns
absorb heat-from the Surrounding medium and
choring those conductors adjacent the periphery
since it frees a corresponding number of holes
for the reception of thermal resistance wire or it
permits a reduction in the diameter of the in
sulator, and a corresponding reduction of the
heat storage capacity thereof.
head end of the tube and the head end of the
thermometer,
It is a still further object of the present in
vention to provide a head structure that is sealed '
to prevent the leakage of ?uid through the head 55
2,181,065
2v
portion of the thermometer. This is of impor
the thermometer is used to measure
the temperature of ?uid under pressure. I pro
vide an adequate seal against leakage or that
?uid through the head oi! the thermometer to the
. tance where
In the drawings:
Figure 1 is a longitudinal sectional view of my
improved resistance thermometer with the cap
and plug separated from the body thereof to
facilitate illustration;
‘
Figure 2 is a diagrammatic view .of the internal
outside atmosphere.
circuit connections;
- \
3 is a longitudinal section, through
It is a still further object of the present inven
tion to make the resistance thermometer in the the thermal resistance element, said view bein 10
taken along the line 3-4 of Figure 4;
_
form of a sealed unit from which all the mois
Figure 4 is a top view of the thermal resist
ture
and
much
of
the
air
has
been
removed
and
10
wherein practically all of the free space is ?lled ance element;
'
'
Figure 5 is an enlarged top view of the resist
with material of a higher heat conductivity than
air. Bye-making it in the form of a sealed unit ance thermometer with the cap and plug portions
free of all moisture, the resistance characteristics
Figure 6 is a view, corresponding to Figure 5,
01 the thermal resistance element is not subject to
15 change by chemical action or by slight mechani
of a three-wire resistance thermometer;
Figure 7 is a longitudinal sectional view illus- '
cal injury. By ?lling the .spaces between the pro
tecting tube and the thermal resistance element trating a modi?ed form of cap structure;
Figure 8 is a circuit diagram;
with material of a higher heat conductivity than
diagrammatically, one
air, I reduce the time lag of the instrument. It is
Figure 9 illustrates,
of
the _ thermoresistance
to be noted that I do not depend upon evacua
method of calibration
tion for the maintenance of the accurate condi
bulb; and
'_~.
removed;
tion of the thermometer.. Since the protective
tube is practically ?lled with solid material, any
,
Figure 10 shows a
p
-
.
modi?ed circuit arrange
meat.
Reference may now be had more particularly to
highly objectionable because the amount of for Figure 1 of the drawings. The resistance ther
eign material that can enter is very small. In mometer of my present invention, which I call
small leak that may develop in the tube is not
the case of an evacuated unit a small leak results
in an immediate loss of the vacuum, and fre
quently starts a rapid deterioration of the unit.
It is a further object of .the present invention
to provide a resistance thermometer, the produc
a “thermoresistance bul ”, is a sealed unit com
prising a thermal resistance element i having
two, three, or four outgoing leads that terminate
at a head portion or terminal support 2, and
which is sealed in a protective tubular casing 3,
tion of which can be standardized for either a
two-wire circuit or a three or four-wire circuit,
the diiierences in construction of the three dif
preferably, although not necessarily, of metal.
ferent types of unit being merely in the terminal
portion of the head of the-unit. The thermal re
sistance element is priovidedv with tour lead
wires that extend towards the head of the ther
The unit is provided with a terminal or jack as
sembly l to establish contact with the leads ex
tending to the thermal resistance element,'and
more particularly in
mometer. In the case of a‘ unit for use with a of wires II and II are soldered together at I! and
so four-lead circuit, all four lead wires extend ,to crimped at IS. A second pair of similar wires l4
similarly soldered together at ii and
terminals at the head 0! the instrument. In the
H. The wires l0, H, II and [5 are
case of a unit for use with a three-lead circuit,
diameter to a?ord the requisite
only three terminals are provided, ‘one lead wire
from the unit being left open. The same three
.45 leads extend to the head of the instrument where
the instrument is to be used in a two-wire circuit.
In this arrangement one of the three leads ex
tends to what may be called a dummy terminal,
strength, and preferably of materialhaving a
and provides means for determining the lead wire
resistance from‘the terminal to the thermal re
drical piece of electrical insulation ll. The
be of any suitable material
the temperatures for
sistance element.
40
very low temperature coeiiicient of resistance,
although the latter is not indispensable. The
lower straight ends of the four wires are in
serted through four center holes it in a cylin
'
The resistance thermometer for min a two
wire circuit is standardized in various sizes and
which the
to
material, and should have a
temperature ranges and is provided with a stand- . as high as possible consistent with good electrical
insulating properties. It should have as low a
ard series compensating resistance of a prede
will be
termined value in excess of any lead and line speci?c heat as possible, whereby there
in tempera- \/
a minimum lag between the change
tered.
known installation, the compensating
is reduced in amount so that the sum of the re
maining compensating resistance plus the resist
line wires from the
the Wheatstone
the resist
ance is of the precise value for which the stand
holes it. The crimped portions serve to anchor
the wires against withdrawal.
Thereafter the ,
irom the following speci?cation taken in con
straight portions 20 are clipped oil at the lower
edge of the insulation is.
The cylindrical piece of insulation is is pro
vided with a number of longitudinally-extending
holes 2i spaced Irom one another adjacent the
edge of the insulation. I have here shown eight
such holes, although any other number may be
junction with the accompanying drawings torm
provided, preferably an even number. Through
ardized apparatus is calibrated.
standardization
various standardized units are
different line wire resistances.
of the above and further ob
'10
75;
ture within the insulation is and that outside of
the body. After' the lower ends 20 of the wires
ll, II, M, and ii are extended through the
bottom of the insulation is, they are gripped by
a suitable tool, such as a pair of pliers, and the
crimped portions l3 and I‘! are drawn into the
ing a part thereof.
2,131,065
these holes is drawn a coil
which extends continuously through the eight
3
Thereafter a series of lead wire spacers of solid
nsulation, indicated at 30,
wires I0, l|,.l4, and I5. If theunlt is to be used
as a four-lead compensation unit, which is quite
infrequent, all four wires l0, H, H, and I5 are
extended to the terminal support. If it is to be 5
used either as a two-lead unit or as a three-lead
10 and, what is more important, a reproducibility
and constancy of resistance. For temperatures
' below 400°
F. nickel is a suitable material.
One
unit, only three wires are extended as far as the
terminal support 2, one of the wires, here indi
cated as the wire ll, being a dead wire terminat
10
end of the wire 23, indicated 'at 24, is soldered to
the conductors I0 and II at the point I2. The
other end, 25, is soldered to the conductors l4
15 and
I 5 at l6.
15
20
20
desired, it may
introduction into the casing.
The tubular casing 3 is
25
30
tom of the casing 3. The portion of the tubu~
lar casing above the disc 3| is then ?lled with 30
insulating cement, indicated at 35, thus securing
the thermal resistance unit in place and sealing
the upper end of the tube 3.
The upper end of the tube 3 is externally
35
threaded to receive the terminal support 2.
terminal support 2 is made of suitable insula~
tion, such as “Bakelite” or the like, and is pro
40
vided with an internally-threaded counterbore 36
practically uniform.
at its lower end.
At the
The holes 2| are then ?lled
solid material to increase the heat conductivity
50
This may
winding around the tube a cord or thread soaked
55
minal support, a coating of sealing cement being
provided at the threads. The nut 40 and the
lower end of the terminal support are provided
with mating circular grooves, corresponding to
the grooves 31-38, which fill with cement, as 65
indicated at 42. The sealing cement 39, together
with the cement coating between the nut 40
in a highly volatile liquid,
The liquid then acts as a car
rier for the solid substance. It is introduced into
the holes and then evaporated away, leaving the
solid material behind.
and the terminal support 2, pr .ents any leak
age of fluid through the inteiior of the nut 40.
The notches or grooves 31-38, and 42 are pro 70
vided with a few spaced indentations that serve
to increase the hold of the cement against be
coming loosened when a turning force is applied
to the respective parts. The lower end of the
2,181,065
4
nut 46 is externally threaded, at ‘4| for mount
ing the resistance thermometer.
The upper end of the “terminal support 2 is
provided, in the case of a unit to be used in a
two-lead circuit, with two socket terminals
45-46, with a variable compensating resistance
41, and with a dummy terminal 46. The lead
conductor I6 is connected to the socket terminal
45, the lead conductor I5 to the'dummy terminal
48, and the lead conductor I4 to one end of the
10 compensating resistance
The other vend of
the compensating resistance is connected to the
socket terminal 46. The lead conductors I6, I4,
and I5 are of identical lengths and, being of the
same size and material, are of identical resist
In Figure 6, I have shown an end view of a re
sistance thermometer ior use with a three-lead
bridge. This construction differs from that 0!
Figures 1 and 5, in that here the compensating 5
resistance is omitted, the same being replaced
by a third socket 41’ similar to the terminal
sockets 45 and 46. The wiring connections at
the terminal post are as indicated in Figure 6,
namely, the lead I6 extends to the socket 46, 10
the lead I4 to the socket_46, and the lead I5 to
the socket 41'. In this case, the plug assembly,
is provided with three prongs, rather
, not shown,
15 ance. Therefore, a measure of the resistance be
tween the terminals 46-46 will give a true value
than two, as in Figure 1. The plug and socket
assembly are polarized so that the two may be
brought together in only one predetermined rel; 15
ative angular relationship. This is accomplished,
in the present instance, by locating the socket 41'
of the lead resistance from the terminals 45-46
‘to the thermal resistance element 23, the com
pensating resistance 41 being included in the lead
20 wire resistance._ An explanation of the reasons
for the compensating resistance will be given as
this description proceeds.
closer to the socket 45 than to the socket 46,
although any other polarizing arrangement may
be used.
‘
The tube 3 is ?lled with solid material to im
20
>
In Figure 7, I have shown a modi?ed form of
cap structure to, be used in lieu of the cap 6 of
Figure 1. The cap is indicated at 5’ and com
prises a molded piece of “Bake1ite" or other suit
able insulation having a fore part adapted to
prove the thermal conductivity between the tube
25 and the thermal resistance element I, thereby to
reduce the time lag of heat transfer between the
thread over the terminal support 2.
‘ re cap is
with an elongated externally-threaded
provided
cylindrical rear projection I66, into which is
placed a number of gaskets I6I through which 30
the conductors extend. The gaskets may be of
any sealing material that expands radially upon
axial compression, such as rubber. Another rub
ber gasket I65, and a pair of thin metal washers
ods of ?lling and other ?lling materials, as pre- , I66, are interposed between the outermost gas 35
thermal resistance element I and the outside of
the tube 3. The ?lling may be powdered alumi
num oxide, introduced in the manner previously
30 described in connection with the ?lling ‘of the
holes 2|. It is to be understoodv that other meth
viously set forth, may be used.
The lower ‘end of the tube is closed, but not
sealed, by a vented disc of insulation 55 and a
ket IM and a nut I62.
vented metal closureplug
sition by a lock nut I66. During turning of the '
nut I62 the washers I66 slide on one another to
The unit is then
placed in an oven and baked to drive out the
moisture. Thereafter the vent hole 51 is sealed
by a plug of solder, or the like, while the unit
on the projection I66, and is then locked in po
prevent turning of the gaskets I6I.
is still hot, thereby precluding the drawing-in
of air or moisture upon cooling of the unit.~ When
the unit cools, the air that may still remain in
the tube is under a partial vacuum.
A thin sleeve 56, of copper or other metal hav
40
An explanation will now be given of the mode
of operation of the two-wire resistance thermom
eter above described, for which reference may be
had to Figure 8. The thermometer is here shown
as threaded into a pipe II6 so that the thermal
45 ing a high heat conductivity and provided with
a number of thin circumierentially-extending
radiating fins 5| may, if desired, be secured to
the tube 3 in intimate heat-conducting relation
thereto and below the end of the nut 46.’ The
50 ?ns absorb heat from the medium in which the
I
I.
45
resistance element extends slightly beyond the
center of the pipe The line conductors 63-44
extend to a Wheatstone bridge I I I, the conductor
64 terminating at the corner N2 of the bridge
and the conductor 63 terminating at one pole of -'
adapted to \
a double throw switch II3 which is
connect either to a bridge resistance H4 or to
unit is immersed and thus prevent the establish
the thermometer resistance. The bridge is ad-'
ment of a temperature gradient along the lower
end of the tube 3 by reason of the loss of heat
through the rather massive head portion of the
justed by first closing the switch H3 at its con 5
tact H5 and then adjusting the resistor II6. to
55 unit.
The insulating cementitious material 39
and the-insulator 2 inhibits the loss of heat
60
The gaskets are com
pressed axially by the nut I62 which is threaded
bring the pointer of an» indicating instrument III
to a predetermined position. This fixes the po
tential applied by the battery to the opposite
through the upper end of the tube 3. Whatever
heat is lost, is readilypicked up by the ?ns 5|,
thus preventing the establishment of a tempera
corners of the bridge. Thereafter the switch t
H3 is closed to its alternate contact and the in
ture gradient along the tube 3, which might
to the opposite corners of the bridge, by the bat
tery, is ?xed it follows that the difference of
potential between the two corners of the bridge
to which the instrument III is connected must
otherwise even alter the temperature at the lower
end of the tube 3.
Circuit connections to a Wheatstone bridge, or
other resistance measuring apparatus is provid
ed in the form of terminals comprising a cir
cular disc of insulation 66 from which depend
two jack terminals 6I-—62 adapted to enter the
socket terminals 45 and 46, respectively. A pair
of insulated line conductors 63-64 extend from
70 the two jack terminals, through an opening in
the cap of insulating material 5. The cap 6
is internally threaded at its lower end, as indi
cated at 64, for threading the cap over the up
per portion of the external threads.
strument I" read. Since the potential applied
be determined by the current ?owing through the
circuit including the resistance element of the
resistance thermometer, which element is con
nected as one arm of the bridge, since the re
sistances in the three other arms of the bridge
are fixed. The scale of the instrument may be
calibrated in terms of temperature as determined
by the. resistance of the resistance thermometer.
It is to be noted that the resistance measured
by the Wheatstone bridge includes not only that
3,181,068
5
I20 is connected to the dummy terminal 40 which,
for this purpose, may be made in the form of a
The other end of this resistor is con
nected to the conductor 63. Thereafter the value
of the resistance 41 is varied until the instru
ment II'I reads a temperature exactly that for
which the resistor I20 is set, in this instance,
say 30°. This means that, if the resistor 23 were
I20 and if the tem
10
10
15
15
tus, namely, the Wheatstone
strument II1.
20 a' portion of the resistance
Otherwise, the instru
installation,
portion chosen being such 41 is removed, the
ment would not read at that set value at that
time. Thereafter the calibrating resistor I 20 is
removed and the line conductor 63 connected
20
to the terminal ii.
In Figure 10 I have shown a circuit arrange
ment for a modi?ed form of resistance unit.
arrangement diil'ers from that of Figure 9
25
I6 are within the casing 3, and inaccessible. It
is for this reason that the dummy terminal 40
is provided. In the manufacture of the resist
?xed at any arbitrary value, say, 8 ohms. Since
This unit is calibrated in the
manner previously set forth in the description of
Figure 9. The calibration is facilitated by reason 30
of the fact that the adjustable resistance is adja
this includes the conductor I5, which is of a re
cent the Wheatstone
sistance exactly equal to that of the conductor I0,
it is clear that the lead wire resistance between
the terminals 45—46 and the points I2—-I6 is
made exactly equal to
ment “1 may be read by the person making the
'
adjustment of the resistance.
In Figure 10 the calibrating resistance I20’,
which
40
45
s method of
?xing the lead and line resistance is particularly
applicable where the length of line 63—64, and
the size of wires used, is accurately known 'so
50 that its resistance value can be subtracted from
the resistance 41 at the factory before the unit
6I'—62 of the line plug shown in Figure l. The
unit I20’ is used only during calibration of the
line,
in the
of
Figure
9. manner set forth in the description
If desired, the line compensating resistance 41
or "a may be incorporated in the plug terminal
5 of Figure 1 rather than in the socket terminal
of Figure 1, or than at the Wheatstone bridge cir
cuit of Figure 10.
50
is shipped for installation. However, where the
length of the line conductors 63—54 is not ac
curately known, it may be necessary to measure
55 the resistance at the installation. Where this
is necessary, it may be desirable to use an ar
rangement such as is illustrated in Figure 9.
In Figure 9 I have shown a circuit arrangement
60
including a Wheatstonebridge III, instrument
“1, and line conductors 63—6l, all arranged in
the circuit shown in Figure 10
wherein the adjustable resistance is immediately
adjacent the Wheatstone bridg .
I
The resistance thermometer shown in Figure 10
provide a. calibrating resistor I20 which is of
an accurately known value, say, a value exactly
is provided with an additional resistor I 30. This
resistor does not correspond, functionally, to the
line compensating resistor 41 of Figure 1. This
the same manner as is shown in Figure 8.
65
resistor is made of such a value that the resist
ance of the loop from the terminal 46, the re
sistor I30, conductors H and I5, to the terminal 65
exactly equal to that
of the resistance of the thermal element 23 at,
say, exactly 30°, although any other arbitrary
point may be chosen.
The resistor I20 is of a
material having substantially zero temperature
coe?icient of resistance, One end oi the resistor
41' is some exact pre-determined amount, say,
for instance, 2 ohms. If the conductors ‘I4 and
I5 are rather long, as with a thermometer where
in the stem 3 is comparatively long, the resistor
I 30 is of a smaller value than where the ther 70
mometer is shorter. By reason of this resistor
it is possible to standardize the lead wire resist
ance from the socket terminals 45-46 to the
thermal resistance unit 23 at a ?xed value re
76
2,131,065 ,
6
comprising a tubular piece of insulation, a sup
gardless of the length of‘the unit. Since the
resistance of the lead wires Ill-ll is not e?ective
port therefor comprising a plurality of wires held
within longitudinally-extending holes in the piece
for temperature measurement, a standardization
of insulation, said holes being located adjacent
of this resistance that is'applied to all sizes of the center of the insulation, said insulation hav
thermoresistance bulbs permits the use of any ing a plurality of longitudinally-extending holes
standardized bulb on any pre-calibrated line. therein adjacent the periphery thereof, a thermal
Thus consider the line 63-g-6l of Figure 10. If responsive resistance wire extending through the
the resistance "a is adjusted so that the total last mentioned holes with the ends thereof ter 10
lead and line resistance from the Wheatstone minating at adjacent ends of adjacent holes and
bridge HI to the thermo resistance unit 23 is connected to the supporting wires and the coils
'10 such that one unit will give correct readings, then in the respective holes connected in series, where
give correct
‘ any other standardized unit will also
- readings, regardless of the length of the stem 3
of the particular thermoresistance bulb. In the
circuit shown in Figure 9 the internal lead wire
resistance of the thermoresistance bulb is ad
justed, at the resistance 41, to fit‘it with the
particular linen-£4 on which the bulb'is to be
used. If a different thermoresistance bulb is
15
by the supporting wires constitute‘ the lead-in
conductors to the thermal resistance and relieve 15
it of mechanical strain.
to be used on this line, it must also be calibrated
20 for the particular line. In the circuit shown in
Figure 10 the resistance 41a standardizes the line
resistance so that any standard thermoresistance
bulb of approximately the same length can be
-. 25
used with the same line. The resistor I30 con
stitutes an» additional refinement that permits
the standardization of various thermoresistance
bulbs of different lengths.
In each of the modi?cations above described,
the internal lead wire 15 is provided solely for the
purpose of obtaining va measurement of the
resistance of the lead-in conductors between the
terminals of the resistance thermometer and the‘
2. In a temperature measuring device, a tem
perature responsive electric resistance unit so
constructed and arranged that it changes inre
‘sistance as a ?xed function of the changes in tem
perature of the ambient medium, said unit com
prising a tubular piece of insulation, a support
therefor comprising a plurality of wires held with
in longitudinally-extending holes in the piece of
insulation, said holes being located adjacent the
center of the insulation, said insulation having at
20
least four longitudinally-extending holes therein
adjacent the periphery ‘thereof, a thermal respon
sive resistance wire extending in series through
the last mentioned holes with the ends thereof 30
terminating at adjacent holes and connected to’
the supporting wires, whereby the supporting
wires constitute the lead-in conductors to the
thermal resistance and relieve it of mechanical
strain, both ends .of the thermal resistance wire 35
being at the same end of the piece of insulation
thermal resistance
‘t 23. Since any change in
thereby
the lead and line wire resistance due to change‘ and in close proximity
35 in temperature is of a negligible magnitude in precluding the establishment of a temperature
comparison with the change in resistance of the difference between them and thus precluding the
thermal resistor wire 23, the lead and line wire formation of a thermocouple at the juncture of 40
the thermal responsive resistance wire and the
resistance may be considered constant at all oper
ating temperatures and, therefore, suitable ad
lead-in conductors.
_
justment for that resistance can be made in the
3. A temperature responsive electrical device
calibration of the resistance measuring appa
I am‘aware, it is fundamentally
for use in a resistance thermometer, said device
including a thermal responsive element, a protec
end of which the element is 45
located, a head portion at the other end of the
casing, said head portion comprising a terminal
~sive resistor in a two-‘wire circuit. In a three
assembly of insulation and a mounting nut, said
wire.circuit it is, of course, not necessary to‘ pro
vide "a line compensating resistor, such as the terminal assembly, mounting nut, and casing be 50
ing secured together, and means for preventing
resistor," or "a.
.
_
.
'
It is to be noted that in the apparatus of the leakage along the surfaces between the protecting
present invention the conductor. [5 must have a casing, the mounting nut, and the terminal as
resistance substantially that of the conductor ‘10, sembly, comprising a layer of heat insulating ce
while the conductor II can be’of any resistance mentitious material along the contacting surfaces. 55.
4. A temperature responsive electrical device
value. In practice the conductors “1-44-45 are
of practically the same resistance. However, any for use in a resistance thermometer, said device
55] difference in the resistance of the conductor l4 » including a thermal responsive‘ element, a protec
is not objectionable because the resistance of this tive casing in one end of which the element is
conductor is measured directly in the adjustment ‘located, a head portion at the other end of the
or the resistance 41.‘ In a three-wire bridge the casing, said head portion comprising a terminal
possibilities of error are double because both the assembly of insulation and a mounting nut, said
terminal (assembly, mounting nut, and casing be
conductors I4 and 15 must be of the same resist
ing secured together, and means for preventing
ance as that of the conductor [0.
In compliance with the requirements of the leakage along the surfaces between the protect
patent statutes, I have here shown and described ing casing, the mounting nut, and the terminal
a few preferred embodiments of my invention. assembly, comprising a layer of heat insulating
cem'entitious material along the contacting sur
It is, however, to be understood that the inven
tion is not'limited to the precise embodiments faces, there being mating annular grooves along
here shown, the same being merely illustrative of the contacting surfaces that are filled with beads
the principles of the invention. What I consider of cementltious material to seal against leakage.
new to compensate for all of the lead and line
wire resistance down to the very thermal respon
new and desire to be secured‘by Letters Patent is:
1. In a temperature measuring device, a tem
perature responsive electric resistance unit so
constructed and arranged that it changes in re
sistance as a fixed function of the changes in
temperature of the ‘ambient medium, said unit
(
5. A temperature res
sive device including a
temperature responsive e ectrical resistance ele
ment, a heat conducting protective casing in one
end of which the element is located, circuit con
ductors extending in said casing to the opposite
7
from the casing, and means formed at the end of
the nut remote‘ from the terminal assembly for
mounting the thermometer.
10
9. A temperature responsive electrical resist
dependently of the sealing of said opposite end of
the casing,
ance for use in a resistance thermometer, includ
of outgoing conductors extending
10
a lead-in conductor
one end of the thermal resistance
15
15
20»
20
25
25
30
30
to the atmosphere sur
rounding the head assembly, and means at the
contacting surfaces of the head assembly for pre
venting-?uid leakage from along the outer surface
of the casing, through the head assembly, to the
atmosphere surrounding the head assembly.
7. A temperature responsive device including a
lead wire resistance to the thermal resistance
element.
11. A temperature responsive electrical resist
ance for use in a resistance thermometer com
prising a sealed unit including a protective casing,
a thermal resistance element within the casing at
one end thereof, a terminal assembly at the other
50
end of the casing, a pair of terminals and a com
pensating resistor
'
'
ends of the thermal resistance element to
terminal assembly,
65
connected to one of the terminals and the other
dummy terminal on the terminal assembly, and a
third conductor extending from said dummy ter
the outer surface 01' the eas
ing, through the head assembly, to the atmos
phere surrounding the head assembly, said means
comprising cementitious material covering the
minal to one end of the thermal resistance e1e~
ment.
12. A temperature responsive electrical resist
ance for use in a resistance thermometer, in
cluding a protective casing,
material in mating grooves at contacting surfaces
of the terminal assembly and the mounting mem
her.
8. A temperature responsive device including a
temperature responsive electrical resistance ele
70 ment, 9. heat conducting protective casing in one
70
nut, said terminal assembly, mounting nut, and
76 protective casing being secured together, the
2,181,065
8
jacent the periphery thereof, a thermal respon
ing where the thermal responsive element is lo vsive resistance‘ wire substantially entirely with
cated by reason of the passage of heatbetween in said holes with both ends of the wire termi
the head portion and the adjacent end of the nating at the same end of said mass, a terminal
assembly at an end of said casing, and lead wires
13. A ‘thermal responsive member adapted to connecting the ends of the thermal responsive
resistance wire to the terminal assembly, the
be inserted into a medium and respond to ther
lead wires being of a material different from that
mal changes of said medium, said member in
cluding a casing, a thermal responsive element of the thermal responsive resistance wire, and 10
within the casing adjacent the end thereof that the ends of the thermal responsive resistance
is adapted to be inserted into the medium, a wire being adjacent one another to preclude the
10 head portion at the other end, and means for establishment of a temperature difference be
the casing tween them and a corresponding thermo-electro
inhibiting the transfer of heat along
motive force at the point of juncture of the dis 15
from end to end comprising heat radiating me
tallic projections on the casing adjacent the head similar wires.
16. A temperature ,measuring system including
portion and between that portion and the op-,
15 posite end of the casing.
responsive electric resistance ele
' a temperature
14. A temperature measuring system compris
ment, 9. pair of terminals for establishing cir
ing a resistance thermometer including a pro
cuit connections with said element, a connector 20
including a second pair of terminals movable
tective casing, a thermal resistance element with
into and out of engagement with the ?rst men
in the casing at one end thereof, a terminal as
sembly\at the opposite end of the casing," in tioned terminals, and a compensating resistance
ternal wiring connections between the terminal in‘ series with the circuit through at least one
assembly and the thermal resistance element, re
set of cooperating terminals of the two pairs of 25
sistance measuring means at a point remote‘ terminals, said compensating resistance being
from the thermometer, a two-wire line circuit located adjacent the terminals and spaced from
extending from the resistance measuring means the temperature responsive electric resistance ele
to the‘ terminal assembly, and means for adjust
ment by an amount su?icient to place it out of
ing the line circuit to compensate for the line the region of the variable temperature meas 80
circuit resistance and the resistance of the in ’ ured by the element.
ternal wiring connections comprising a compen
17. A temperature measuring system including
sating resistance in series with the line and a temperature responsive electric resistance ele- ,
means for establishing a loop resistance measur
ment, a pair of terminals for establishing cir
casing.
'
'
ing circuit comprising the compensating resist
cuit connections with said element, a connector 35
ance, the line circuit and conductors extending
from the terminal assembly to the thermal re
sistance element but'excluding that element.’
‘
,15. In a temperature measuring device, a
temperature responsive electrical resistance unit
so constructed and arranged that it changes in
resistance as a ?xed function of the changes
40 in temperature of the ambient medium, said uni
including a protective casing and, within said
casing, a thermal resistance element comprising
45
a comparatively long and narrow mass of insu
lation having longitudinally extending holes ad- I
including a second‘ pair of terminals movable
into and out of engagement with the first men
tioned terminals, and a compensating resistance
in series with the circuit through at least one
set of cooperating terminals of the two pairs of 40
terminals, said compensating resistance being
mounted as one physical unit with one of said
pairs of terminals and located outside of the
region'of the variable temperature being meas
ured.
JOHN A. OBERMAIER.
-
45
Документ
Категория
Без категории
Просмотров
0
Размер файла
1 341 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа