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Патент USA US2133967

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foci. 25, 193s..
2,133,967
L. B. M. BUCHANAN
CONTROL FOR REFRIGERATING APPARATUS
Filed Augflß. 1937
L'
as
F70» E.
WITNESSES
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LssL/z B. M DucHmvnN.
6_ H
BY
ATTORN
mensa oci, 2s, 193s
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i,
V2,133,967-
UNITED STATES ‘PATENT OFFICE
CONTROL Fon REFRI'GERATING >APPA
nATUs
Leslie B. M. Buchanan, Springfield, Mass., al
signor to Westinghouse Electric & Manufac
turing Company, East Pittsburgh, Pa., a cor
poration oi' Pennsylvania
’
Application August 18, 1937, Serial No. 159,858
'10 Claims.
My invention relates to refrigerating apparatus
and has -for an object to provide an improved
control therefor,
~
` A further object of my invention is to control
5 the operation of a refrigerating machine in response to the temperatures’or different zones
being cooled,
.
.
.
A further object of the invention is to limit
10 the maximum temperature of a cooling element
(Cl. 62f-4')
sponse to a predetermined low temperature of
aIlOther zone.
Reference will now be had to the drawing
wherein I have disclosed a cabinet structure I0
ÍOI’med Of insulating Wells and Cleñning e Cham~ 5
ber II for articles to be refrigerated. An evapo
rator I2 of any suitable type is disposed in heat
transfer relation with the air in the chamber II
and may include means fOI‘ SUDDOrtinE trays I3
of a _refrigeraung machine and the 'minimum ' in which media to be concealed Or maintained 10
temperature of the media coded thcrebic
A still further object of the invention is to
provide an improved thermostatic control for a
_ refrigerator that responds to temperature con“’ ditions inaplurality of remotely disposed regions.
These `¿md other Objects are effected by my
' 2
at sub-freezing temperatures may be disposed.
Circulation of refrigerant through the evapo
ratOr l2 iS effected by a refrigerant condensing
unit generally Shown at M and Preferably in“
olndïng a Compressor '5 driven by. on oloomo 15
motor i6, and a condenser I‘I, the latter being
invention as will be apparent from the following
cooled 1n any Won known manner suon as’ for
description and claims taken in connection with
example’ by moans »of o fan -w- Refrigerant
the accompanying drawing, forming a part of
vaporized in the evaporator I2 at relatively low
this appiicaticn’ in which:
pressure and temperature by heat abstracted 20
Fig i is a diagrammatic viow of a refrigerator irom the air 1n thechainber II and the media
mechanism controlled in accordance with my in- ~ m tno trays ‘3 lo Withdrawn from the evaporator
vention; and
I2 through a suction conduit I9 by the com
Fig_ 2 is a sectional View taken along the iine pressor I5. The withdrawn vapor is compressed
'25
H_H of a detail shown in Fig i.
to a relatively high pressure by the compressor 25
I have Chosen to show my invention oopiiod
I5 and is delivered through a conduit 2| to the
to a conventional single evaporator refrigerator
of the domestic type but it is to be understood
30 that other forms of refrigoroting apparatus may
be controlled equally well including two temperature machines wherein a plurality of evaporate“
oondonser '_7 Wnerein'it is Cooled and o.ondonsrd'
Liqmd refrigerant passes from the cçndenser n
to the evaporator. I2 through aconduit 22 having
a suitable expanslon device’ Such as' for example’ 30
a conventional capillary tube 23 connected there
are employed and Operatm at different tempera_
ln. The pressure of the refrigerant is reduced as
tures
it passes through the tube 23 so that vaporiza
The present ,inveâtion deñnes an im_
,
35 provement over the control shown and claimed
in my oopending application» Serial No- 159:6571
ñled
0f the
August
present
18, applicatiOn.
and assigned
In this
t0 theCODending
assignee
application, I have disclosed a. control of the gen40 eral type vshown in the present application applied to various forms of refrigerators including
, a form wherein two different temperatures are
maintaincd in diñcrcni; cbambers~
The control disoicsod in the present ar,oiioiaf
tion at relatively low temperature may be ef~
¿eoted in the evaporator ‘L The system de_ 35
scribed heretofore operates on the well known
be
compressolmcondenser-expander
understood that other forms cycle
of refrigerating
but
systems may be employed and controlled in ac
cordance with the invention.
,
40
In practicing my invention, I provide a con'
tr01 mechanism generally ShOWl'l at 25 fOr ini
tiating and terminating operation of the con
densing unit I4 in accordance with temperature
tion operates in a similar manner to the control
âfälditmns “il digêäemi zàmes of the cäìmäîrl‘ H’ 45 c
is an improvement thereover lin that Ithe mini-
municating with a plurality of reservoirs zo and
of the aforementioned copending application but zo îlarxîâëa; âllnbe zìnccoänììäëà ïílrêîgtso aîldecâïî
mum temperature maintained m the higher tem"
50 peraturo zone may be in err-cess of the maximum
temperature of the low temperature zone. In
both the present and the copending applications,
operation of the compressor is initiated lin response to a predetermined high temperature of
55 one zone being cooled and is terminated in re-
29 for containing a volatile ñuid. The reservoirs
28 and 29 may be of any suitable construction 50
but’ as shown, are defined by bulbs communi.
gating with the tube 21,
The charge of fluid in the system deñned by
the bellows 26, the tube 21, and the reservoirs 29
and 29 is such that liquid is present in one of u
'
2,133,967
E
the reservoirs 23 or 29 while the remaining res
ervoir, the tube 2ï and the bellows 26 contain gas.
The pressure in a thermal responsive system
charged in this manner will always correspond
the spring 3i and lever 39 permits' overtravel of
the lever 33' with respect to the lever 39 during
a movement of these members and subsequent to
the engagement of the lever 39. with one of its
stops ¿52 and 33.
_A switch mechanism generally indicated at 44
is actuated by the lever 39 and includes a station
ary contact shown diagrammatically at Q5 and a
of lowest temperature and, therefore, vthe pres
movable contact d3, the latter being carried bya
sure of vaporization is determined by thertem
perature of said low temperature region. It will ` movable support 37 pivoted at ¿i8 to the. frame. 10
An over-center spring ¿i3 connects the lever '39
be apparent, therefore, that normally the reser
voir 28’ being in heat »transfer relation, with the to the support di and eii‘ects a snap-action of the
e'vaporator i2 or ina zone of low temperature is latter in a switch’closing and opening direction
the lowest temperature portion! of the thermal as the center ofthe spring passes the center of
the pivot- 33. Downward movement ofthe con
responsive system and contains the liquid. Ac
cordingly, expansion of the bellows is responsive tact support di is limited by a stop> 5i. The
to the temperature of the reservoir 23 and the switch mechanism 34 which I have shown defines
evaporator 62. Should the temperature of the one'form that may be employed', but it will be
reservoir 28 be heated to a value in excessoi the understood 'that `any suitable form oi switch
20
mechanism may be used.
_
temperature of the reservoir 29 which is normal
The compressor motor i6 is energized from a
ly higher in temperature than the reservoir 28,
suitable power source represented by line conduc
the iiuid vaporized in the reservoir 23 would con
tors Lr-Lz under control of the switch 35i. Clos
dense in the reservoir 29 and, therefore, move
ment of the bellows 23 would be in accordance ing and opening of the switch initiates and termi
with the temperature of the reservoir 29. As the nates operation of the motor i5 and the com 25
'
’
rese-“voir 29 responds to the temperature of the pressor i3.
‘
Operation v
air in the chamber li, movement of the bellows
would bein accordance with the temperature of
.As shown in the drawing, the switch ¿i4 is open
the air in the chamber ii or higher temperature as the temperature oi the evaporator i2 is below
the value at which operation of the compressor 3.0'
zone.
to the lowest temperature to which anypart of
the system is subjected. The reason for this op
eration is because the fluid collects in the region
In order that the- control of the movement of . is started., Circulation of >condensed refrigerant
the bellows may be transferred from the low in heat transfer relation with the thermal ele
temperature reservoir 28 to thereservoir 29, suf- , ment or reservoir 28 is not effected at this time
ñcient heat is imparted to the reservoir 28 to ele
so that this reservoir is colder than the reservoir
vate its temperature above that of the reservoir
23 and, therefore, controls expansion of the bel
23. This may be accomplished in’ any suitable
manner but, preferably, I employ the heat of the
condensed liquid for this purpose. Accordingly,
lows 23. The pressure in the bellows 26 is rela
tively low so that thelever 33 engages the stop 38.
a portion'of the conduit 22 is disposed in heat
d0 transfer relation with the evaporator I2 and the
reservoir 23, as shown at 3i. During operation
of the compressor I5, the circulated refrigerant
heats the reservoir 28 so that control is efîected
by the reservoir 29 and during inactive»periods
of the compressor when circulation of refriger
ant and heating of the reservoir 28 is substan
tially terminated, the reservoir 23becomes the
controlling element. Further reference to the
transfer of control of the expansion oi the bel
`so
lows 23 will be madehereinafter.
»
The construction oi the thermostat 25 will now
be described in detail. A frame member 32 pro
vides a support for the various elements of the
thermostat mechanism 25 and has the bellows
55 23 secured thereto in any suitable manner.
‘Movement of the bellows 26 is imparted to a lever
33 that swings about a fixed pivot 34. A‘spring
35 biases the bellows 26 in opposition to the pres
sure therein and bears against an adjusting screw,
In the description which follows, itv will _be
assumed that the compressor is started -_in re
spense to a predetermined maximum evaporator 40
temperature of 30° F. and stopped when the tem
perature of the air in the space i! has been de
pressed to 42° F.- The maximum temperature of
the air in the space il ‘at the time of starting the
compressor and the minimum temperature of the. 45
evaporator l2 at 4the time of stopping the com
pressor will vary, depending upon their respective
heat loads. In the description which follows, it
will be assumed that the. temperature of the air
in the space ii increases to 45° F. during the in 50
active periods oi’ the compressor and that the
minimum temperature of the evaporator l2 is
24° F.
The stop 33 is adjusted to limit downward
movement of the lever 33 and contraction of the 55
bellows when the pressure in the bellows corre
sponds to a temperature somewhat lower than
30° F., say 29°v F. The other stop 37 limits upward
movement of the lever 33 and expansion of the
bellows 23 when the pressure corresponds to .a >60
temperature somewhat in excess oi 42° F., such as
43° F. The amount of movement oi the lever
39 permitted by the stops d2 and 43 is just suf
iicient to permit operation of the switch 44 and
is of less angular extent than the amount of 65
movement 'of the lever 33.
60 shown at 33. Upward and downward movement
of the lever 33 is limited by respective stops 3l '
and 38 which are adjustable as shown.
A second lever 39 may >be carried by the pivot
345 and is actuated by the lever 33 through a lost
65 motion connection preferably including a spring
di secured to the lever 33 and engaging the lever 39
As operation of the compressor has just been 1
as best shown in Fig. 2. The spring is moved by
terminated by the opening of the switch as, the
the bellows 23 and the Alever 33 and eiîects move
ment of the lever 39 through frictional engage
70 ment therewith. Upwardand downward move
ment of the lever 39 is limited by stops 42 and
43, respectively, which may be made adjustable
as shown. The angular movement of the lever 33
is greater than the angular movement of the lever
-75 39 so that the lost motion connection deñned by
temperature'of the air in the chamber ii is 42°
F. and the temperature of the evaporator is 24° F. 70
Heating of the reservoir 28 by the warm con
densed refrigerant is terminated so that the res
ervoir 28 becomes colder than the reservoir 29
and, therefore, becomes the controlling factor for
determining pressure in thebellows 26. As the
nsv
alsace?
3
temperature of the evaporator l2` and of the air ‘ that its maximum temperature is about 32' F. `
in the space Il increase due to the heat load whereby defrosting during each cycle is effected.
thereon, the pressure within the bellows progres
sively increases. Expansion of the bellows is pre
vented by the bias of the spring 3l until the pres
gure therein obtains a value corresponding to
As the minimum air temperature is maintained .
at a predetermined value, variations-of the mean
temperature thereof are relatively small during
relatively wide variations in the ambient or room
temperature. The maximum cabinet air temper
As the temperature of the evaporator increases ature will vary with variations in ambient tem
above 29° F., the'pressure within the bellows 28
10 is suiiicient to` start lupward movement of the perature but the variations in the mean tempera
ture are substantially reduced over a conventional
-lever 33. Upward movement of the lever 39 is control in which the circulation of refrigerant is
also enected, belng'frictionally engaged with the under control of the temperature of the evapora
spring Il. When the temperature of the evap
tor. In the latter case, the mean temperature is
orator is increased toa value of 30° F., the lever subject to wide variation whenthe ambient tem
15 39 will have been moved suiiiciently to eiïect en
perature varies as the cabinet air exerts substan
gagement of the contacts 43 and 48. The motor tially no control over the refrigerating machine.
I9 is therefore energized and circulation of re
In the present system, the temperature diiîer
-frigerant by the compressor I5 is started. Heat
ential of the evaporator will vary with different
ing of the reservoir 23 is initiated so that vcon
20 trol of the pressure in the bellows is transferred ambient temperatures although the maximum
evaporator temperature is maintained substan
t-o the reservoir 29. As the reservoir 29 is sub
tially
constant. When the -ambient temperature
jected to a relatively high temperature of air in is high, the compressor is operated for longer
the space Il, the pressure in the bellows rapidly periods in order to depress the cabinet air tern
increases. At this time, the temperature of the perature to 42° F. and, therefore, the minimum
vals air in the space Il is relatively high, for exam evaporator temperature may be depressed to vai
ple, 45° F.
.
The rapid increase in pressure in the bellows
26 eñects upward movement of the lever 33 until
it engages the stop 3l. Upward movement of
the lever 39 is prevented, however, by the stop
42 and, therefore, overtravel of the lever 33 with
respect to. the lever 39 is permitted by the lost
motion connection defined by the spring 4l of
the lever 39. Operation of the compressor `l5
effects a reduction in temperature of-the evap
orator i2 and the air within the space Il. The
pressure within the bellows 2S is progressively
decreased but contraction of the bellows is not
effected at temperatures above 43° F. as the bias
10
15
20
25
ues below 24° F. The minimum evaporator tem
perature therefore is reduced as the temperature
of theA ambient or room atmosphere increases.
The maximum evaporator temperature is main
tained substantially constant for varying ambient 30
temperature but the temperature differential of
the evaporator varies inversely with variations
in ambient temperature.
In control systems wherein the temperature of
the cabinet air controls the refrigerating machine,
a substantially constant mean air temperature
may be obtained but the temperature of the evap
orator will vary so that it may operate above and
below a freezing' temperature at different times
of the spring 35 is insuiiicient to overcome the depending upon the temperature of the ambient
pressure in the bellows. When the temperature atmosphere.
of the air has been depressedv to 43°, the bias
It will be apparent that my improved control
of the spring 35 is sufficient to overcome the pres
provides for the selection of various temperatures
sure in the bellows 26 and initiates downward of .the different zones being cooled and that the
45 movement of the lever 33 so that it is moved minimum temperatures of the higher temperature
out of engagement with the stop 3l.
zone may be higher than the vmaximum tempera
As the spring 4| engages the lever 39, the lat
ture of the lower 'tempera-ture zone. By adjusting
ter moves downwardly with the lever 33 and out the stops 31 and 38, the temperatures at which the
of engagement with the stop I2. When the tem
switch M is opened or closed may be varied, and '
50 perature of the air within the space II has been , the mean temperatures of the evaporator and of
depressed to 42° F., the lever 39 will have been the cabinet air may, therefore, be varied relative
moved suii‘lciently to effect opening of the switch to each other.
44. Accordingly, operation of the compressor and
While I have shown my invention in but one
heating of the reservoir 23 are terminated and form, it will be obvious to those skilled in the
55 the reservoir 23 again becomes lthe controlling
that it is not so limited, but is susceptible 55
factor for determining the pressure within the art
of various changes and modifications without
bellows 28.
departing from the spirit thereof and I desire,
As the temperature of the reservoir 23 is rela
therefore,
that only such limitations shall be
tively low or at a value of 24° F. at this time, the
60 pressure in the bellows is rapidly reduced Aand placed thereupon as are imposed by the prior
art or as are speciiically set forth in the append eo
the bellows, therefore, contracts until the lever ed
claims.
33 engages the stop 39 which as mentioned here
What
I claim is:
.`
inbefore occurs when the pressure within the bel
1. In refrigerating> apparatus, the combina
lows 2B corresponds to temperatures of 29° F. and ’
tion of means defining relatively low and high
65 below. The complete cycle of operation has now
y temperature zones to- be refrigerated, evaporator
been described._
~
,
v
means for abstracting heat from both zones,
From the foregoing description, it will be ap
parent that I have provided an improved control , means for circulating refrigerant through the
evaporator means, a switch _for initiating and
for a refrigerator wherein the minimum tempera
70 ture of the air in the refrigerated zone and the terminating’operation of the circulating means,
maximum temperature of the evaporator are a thermostatic device for actuating said switch
maintained at predetermined values by a single and including first and second elements respon
control mechanism. Accordingly, the evaporator sive, respectively, to the temperatures of the low
may be operated at sub-freezing temperatures for and higher temperature zones, said element re
75 preserving frozen‘articles or may be operated so sponsive to the temperature of the low temper
ature zone being eifective to clo‘se the switch
2,138,967
è
during inactive periods of the circulating means,
means effective during active periods of the cir
culating means for transferring control of the
switch to the element responsive to the temper
ature of the higher temperature zone whereby
said element is rendered eiîective to open the
switch and means for transmitting movement of
the thermostatic device to the switch and pro
viding for overtravel of the device with respect
to the switch so that movement is imparted to
the switch during the first portion of a movement
a thermostatic device including a bellows and
ñrst and second thermal responsive elements
communicating with the bellows and containing
a lvolatile fluid, said first and second elements
being disposed in heat transfer relation with the
respective low and high temperature zones, said
thermal responsive element associated with the
low temperature zone determining the pressure
in the bellows during inactive periods of the cir
culating means, means r‘or increasing the tem
perature of the element associated with the low
of the thermostatic device and relative move ' temperature zone to a value in excessl of the
ment between the thermostatic device and the temperature of the other thermal responsive
element during active periods of the circulating
switch is permitted during the remaining por
tion of the movement of the thermostatic device. means whereby said other‘ element determines
the pressure of the fluid in the bellows, adjust
2. In refrigerating apparatus, the combina
tion oi means defining relatively low and high able means for limiting the range of movement
temperature zones to be refrigerated, evaporator of the bellows, a switch for initiating-and termi
means for abstracting heat from both zones, hating operation of the circulating means, a
movable member for actuating the switch,
20 means for circulating refrigerant through the
.evaporator means, a» switch for initiating and means for determining the range of movement
terminating operation of the circulating means, of the movable member and means for transmit
ting movement of the bellows to the movable
a bellows for actuating the switch, first and sec
ond elements communicating with the bellows- member and providing for overtravel of the bel
lows with respect to the movable member subse
25 and enclosing a volatile iiuid, said iirst and 'sec
quent to an operation of the switch.
ond elements being disposed in heat transfer re.
5. In reirigerating apparatus, the combina
lation with the media in the low and high tem
tion
of means defining first and second zones to
perature zones, respectively, ‘a mechanism for
transmitting movement of the bellows to said be refrigerated at diüerent temperatures, evap
30 switch and eñective to operate the switch during> orator means for abstracting heat from both
the iirst portion of a movement of the bellows zones, means for circulating refrigerant through
the evaporator means, control means for initiat
and to permit overtravel of the bellows with re
spect to the switch during the remaining portion
of the movement of the bellows, and means ef
35 fective‘during operating periods oi the circulat
„
20
25
30
ing and terminating operation of the circulation
i means, thermal-responsive means for actuating
the controlmeans and responsive to a Apredeter- I
ing means for raising the' temperature oí" the- mined temperature of the low temperature Zone
element associated with low temperature zone for initiating operationv of the circulating means
to a value in excess ci the temperature oi the and responsiveto a predetermined temperature
element associated with the higher temperature of the higher temperature zone for terminating
operation of -the same,l said zones being main- ,
zone.
y
3. In a refrigerating apparatus, the combina
tion of means deñning relatively low and high
temperature zones to be refrigerated, evaporator
means for abstracting heat from both zones,
45 means for circulating refrigerant through the
evaporator means, a switch for initiating and
terminating operation of the circulating means,
a >thermostatic device including a bellows and
tained between diiierent high and low tempera
tures and the low temperature of _the high tem
perature zone being of higher value than the
high temperature of the low temperature zone.
d. in refrigerating apparatus, the combination 4.5
of means defining ñrst and second zones tovbe
refrigerated at different temperatures, evaporator
means for abstracting heat- from both zones,
iirst and secondthermal responsive elements means for circulating refrigerant through the
evaporator means,`a switch for energizing and 50
50 communicating with the bellows and containing ’ deenergizing the refrigerant circulating means, a
an expansible ñuid, said iirst-ancl second ele
ments being disposed in heat transfer relation movable member actuated in response to the tem
with'the respective low and high temperature perature of the low temperature zone during
zones, a switch for initiating and terminating periods when the circulating means is deenergized
and actuated in response to the temperature of. 55
55 operation ci the refrigerant circulating means, the high temperature zone during periods when
adjustable means for determining the range oi
the circulating means is energized, means for
movement of the bellows, means for transmit
limiting
the movement of the movable member,
` ting movement of the bellows to the switch and
a mechanism for imparting movement of the
providing for overtravel oi the bellows subse
movable member to the switch and including a GG
'60 quent to an operation of the switch, said ther
mal responsive element associated with the low connection permitting overtravel of the movable
member subsequent to an operation ofthe switch,
temperature zone being effective during inac
and means for adjusting the amount of overtravel
tive periods of the circulating means for deter
mining the movement of the bellows, and means permitted by said connection.
7. ln refrigerating apparatus, the combination
for rendering the thermal responsive element~
65
_ associated with the high vtemperature :tone eüec
of means defining a chamber to be refrigerated,
an evaporator for abstracting heat from said
chamber, means for circulating refrigerant
through the evaporator, a switch for energizing
and deenergizing the circulating means, thermal
Ily operated means for actuating said switch and
responsive to the temperature of the evaporator
for Yclosing the switch and to the temperature of
the media in said chamber for opening the same,
terminating operation of the circulating means, . a lost motion mechanism .for imparting move
tive for controlling the movement of the bellows
during active periods of the circulating means.
4. In reirigerating apparatus, the combina
70 tion of means dei‘lnlng relatively low and high
temperature zones to be refrigerated, evapora
tor means for abstracting heat from both zones,
means for circulating refrigerant through the
evaporator means, a switch for initiating and
'e
e
2,188,907
ment of the thermally operated means to the
switch and providing for overtravel of the. mech
anism subsequent to an operation of the switch
and means for adjusting the amount of overtravel
oi the mechanism whereby the temperatures at
which the switch is opened or closed may be
varied.
l
8. In refrigerating` apparatus, the combination
of means deilnlng a chamberI to be refrigerated,
an evaporator _for abstracting heat from said
chamber, means for circulating -refrigerant
through the evaporator, a switch for energizing
and deenergizing the circulating means, an ex
pansiblel bellows for having thermal elements
communicating therewith and disposed respec
tively in heat transfer relation with the evapora
toi- andthe media cooled thereby, said elements
and bellows enclosing an expansible iluid, a lever
for actuating said switch, means deilning a con
20 nection between said bellows and said lever and
providing for overtravel of the bellows with re
spect to the lever, means for adjusting the amount
of said overtravel whereby the temperature at
which the switch is opened or closed may be
raised. and means for transferring control -from
one of said thermal elements to another so that
the element associated with the evaporator is
effective during inactive periods of the circulat
ing means and the element associated with the
media being cooled is elective during active
periods thereof..
,9. In refrigerating apparatus, the combination
of means defining a chamber to be refrigerated,
an evaporator for abstracting -heat from said
5
tively in heat transfer relation with the evapora
tor and the media cooled thereby, said elements
and bellows enclosing an expansible iluid, means
for selectively rendering the thermal elements ef
fective to control expansion oi the bellows so that 5
the element associated with the evaporator is ac
tive during deenergized periods of the circulat
ing means and the element associated with the
media cooled by the evaporator is eii’ective dur
ing energized periods of the circulating means, 10
means for limiting the amplitudes of the bellows,
a lever for actuating the switch, means for limit
ing the movement of the lever and defining a
. range of movement therefor and a frictional con- .
nection between the bellows and said lever where 15
by movement of the bellows is imparted to the
lever when the latter is intermediate the limits of
its range of movement and movement of the bel
lows relative to the lever is permitted when said
lever is at one of the limits of its range.
tion of means defining a zone to be cooled, an
evaporator for abstracting heat from the media
in said zone, means for circulating refrigerant
through the evaporator, means for controlling the
operation of the circulating means and movable
to ñrst and second positions wherein the circu
lating means is active and inactive, respectively,
means for actuating the controlling means and
pansible bellows for having thermal elements
communicating therewith and disposed respec
2.5
including elements responsive, respectively, to the 30
temperature of the evaporator and the media
cooled thereby, means for selecting the element
which is to actuate the controlling means and
means deñning a lost motion connection between
chamber, means for circulating refrigerant fthe actuating means and -the controlling means
through the evaporator, a switch for energizing and providing for overtravel ofthe actuating
and deenergizing the circulating. means, an ex
20
10. In refrigerating apparatus, the combina
means with respect to the controlling means sub
sequent tooperating the controlling means.
LESLIE B. M. BUCHANAN.
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