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Патент USA US2112791

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March 29, 1938.
‘
N. M. SMALL ET AL
RIEFRIGERATING SYSTEM
Filed March 28, 1936
2,112,791
\
2 Sheets-Sheet l
March 29, 1938.
N. M. SMALL ET AL
2,112,791
REFRIGERATING SYSTEM
Filed March 28, 1956
2 Sheets-Sheet 2
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Patented Mar. 29, 1938
' 2,112,791
UNITED STATES PATENT OFFICE
2,112,791
REFRIGERATING SYSTEM
Norman M. Small and Leon Buehler, Jr., Waynes
boro, Pa., assignors to Frick Company, Waynes
boro, Pa., a corporation of Pennsylvania
Application March 28, 1936; Serial No. 71,485
.15 Claims. (01. 62-2)
This invention relates to refrigerating systems
?uid pressure in accordance with this .invention.
and more particularly to capacity control means
for refrigerating compressors which are auto
loading valve for returning the capacity control
matically operable in accordance with conditions
in the refrigerating system.
In refrigerating plants a plurality‘ of compres
Cl
Fig. 2 is a sectional view of an automatic un
means operating ?uid back to the fluid supply
source.
'
Fig. 3 is a vertical sectional view through a‘
compressor cylinder and one of the capacity con
sors have been installed in which case one or more
compressors can be shutdown during cool or cold trol ports in connection with ?uid pressure oper
seasons and thus reduce ‘the refrigerating ca- _ ating mechanism.
Fig. 4 is a sectional view of a modi?ed form
10 pacity of the compression side of the plant.
However owners frequently desire to have all the of the fluid pressure operating mechanism for
compressor capacity in a single unit with means the capacity control ports.
Fig. 5 is a fragmentary sectional view showing
for varying the volumetric displacement and the
a modi?cation of part ‘of the unloading valve
present invention relates to this type of installa
shown in Fig. 2.
_
15
15 tion.
Referring to the drawings this invention is
Capacity control using the method of reducing
the effective stroke of the compressor by by-pass
ing part of the gas in the cylinder between the
piston and discharge valves to the suction side
,20 of the compressor is old in the art and is not
' claimed as a part of this invention.
The present invention relates particularly to
capacity control for refrigerating compressors al
though it may be used to equal advantage for air
N.) Cl compressors, gas compressors,_ and other types‘
of ?uid compressors.
An object of the invention is to provide means
whereby the volumetric displacement of a com~
pressor can be controlled by either hand or by
30
automatic means.
1
Another object of the invention is to provide
means for varying the volumetric displacement
of a compressor automatically controlled by tem
perature responsive means.
Another object of the invention is to provide
in a refrigerating system automatically operable
means for operating compressor capacity control
means in accordance with temperature of the re
frigerant in the low side of the system.
A further object of the invention is to provide
in a refrigerating system means for operating‘
compressor capacity control means in accord
ance with the vtrue saturated temperature of re
frigerant in the low side of the system which cor
45 responds “to the back pressure of the expanded
gas regardless of what the superheat temperature
of the expanded gas in the low side of the system
may be.
-
shown by way of example applied to a two cylinder
compressor I0, however, the invention is appli
cable to a_single cylinder compressor or of any
number of cylinders. In the arrangement shown 20
the compressor is provided with a crank case I I,
and a suction conduit I2 communicates with the
compressor intake chamber I3. The compressor
is provided with the usual discharge valves lo
cated in the valve head I4 in the cylinder head as
shown in Fig.3 and compressed gases are con- .
ducted through a discharge line I5 leading to a
condenser and receiver I6. From the receiver re
frigerant ?uid is conducted through a hand con
trol valve Mia and conduit II to an evaporator I8 30
which may be a cooler of any desired type, an ex
pansion valve I8a controlling the discharge of
liquid refrigerant thereinto. The gaseous re
frigerant is then returned from the evaporator
to the compressor through the suction conduit I2.
As shown in Fig. 3 each cylinder is provided
with a chamber I9 extending upwardly from the
intake chamber I3 towards the head of the com
pressor, and the intake chamber I3 is shown pro
vided with an inlet port 20 communicating with
the interior of the compressor cylinder 2| beneath
the piston 22 therein; this piston is provided with
the suitable types of sealing rings'and valves as
indicated. In order to vary the compressor ca
pacity a port 23 communicating through the wall
of the cylinder 2| with chamber I9 is positioned
to provide ~the required capacity reduction of they
compressor. This port provides communication
Other objects, details and advantages of our ' with the cylinder 2| above piston 22 with the
invention will be apparent from the following chamber I9 so as to permit gas to ?ow from the
description of the embodiments thereof shown in cylinder therethfough into the suction chamber
I3 and through the suction port 20 during a
the accompanying drawings, wherein:
_
'Fig. 1 is a perspective view of a refrigerating portion of the upward stroke of the piston. As
indicated, piston 22 has moved upwardly to the
' system showing a compressor provided with ca
55 pacity control means automatically operated by upper edge of port 23 to close the communication
2
2,112,791
with chamber l9 and ‘on further upward move
ment it operates to compress the remaining gas‘
' in the compressor cylinder 2|.
The distance the edge ‘of the port 23 is lo
cated from the head of the compressor depends
upon the amount of capacity reduction desired,
' for example, in Fig. 3 it is located at ?fty per
cent of the stroke of the piston which gives ap
proximately ?fty per cent capacity reduction. If
; 10 a greater capacity reduction is desired the up
per edge of port 23 must be closer to the head
of the compressor, and for a less capacity reduc
tion the port must be lower in the cylinder. The
position of the port in accordance with the re
v15 quired capacity reduction is preferably deter
mined and ?xed at the time the compressor is
constructed.
As shown in Fig. 3 a valve cage 24 is mounted
in ?anges 25 formed in chamber I9 and it extends
20 through an aperture in the exterior wall thereof.
The inner end of cage 24 seats on a gas tight
gasket 26 between it and the compressor cylin
der wall. Cage 24 is provided with a port 21
communicating with port 23 into the interior of
the cylinder and ports 28 communicating with
chamber H) which ports provide passageways
through which gas may be permitted to ?ow as
stated above. This cage 24 acts as a guide for a
valve 29 slidingly mounted therein and which is
30 operable to close the passageway into the com
surrounding plunger 39 which seal as shown
includes a ?exible packing ring and a retainer
ring cooperating therewith and secured to the
end wall of casing 32' by means of screws or‘
the like.
,
It will be noted in the foregoing valve equip
ment, which is a preferred construction although
other forms can be employed for the purpose of
this invention, that with the hand control in the
position shown in Fig. 3 the Valve 29 closes port 10
23 for the full volumetric capacity of ‘the com
pressor, but when the hand wheel is turned to
disengage the stem head 35 from piston 3| valve
29 will be forced by the compression in the
cylinder to an open position pushing with it 15
piston 3| in its cylinder casing 32.
Piston 3|
is adapted to be operated by ?uid pressure be
hind it entering cylinder 32 through a ?uid con
duit 43 communicating therewith.
Cylinder 32
is also provided with ?uid return conduit 44 20
communicating with the other side of the piston
and as shown in Fig. 1, the ?uid return conduits
for each cylinder 32 are interconnected between
the various cylinders and conduct the ?uid to
the compressor crank case, although any suitable 25
source of ?uid supply‘ may be employed other
than the crank case if desired. The ?uid con
duits 43 of the cylinders 32 are interconnected
and coupled with a ?uid pump 45 which has a
supply conduit 45 leading to it from the source 30
pressor cylinder, thus causing the compressor
of ?uid supply,—as shown the crank case M of_
to operate under full capacity.
the compressor.
'
As shown valve 29 is held closed by a' plunger
30 extending from a piston 3| which is slid
35 ingly mounted in an operating cylinder casing
32 which is secured by means of bolts 33 to the
outer wall of chamber l9 with a gasket 34 of
circular cross section between the end of the
cylinder member 32 in the wall of the cham
ber. This gasket forms a gas tight seal and
permits easier alignment of the cylinder with
the valve cage chamber for the valve 29. Piston
3| may be held in the valve closing position as
shown by the engagement of the head 35 on a
45 stem 36 which is provided with a manual operat
Fluid pump 45 is shown operatively connected
by means of a coupling 41 with an electric motor
43 which receives its operating current from a
suitable source of electric power supply indicated
by electrical conductors 49 through a switch 5|]
in the circuit‘ for controlling the operation
thereof.
Switch 59 controlling the operation of the
motor driven pump is actuated by a bellows 5|
by either temperature or pressure of a storage
room or any part of a plant in which'the tem
perature or pressure is to be maintained within
close limits. As shown in Fig. 1 this bellows 45
is contolled by a thermal element 52 cooperating
with the suction conduit |2 of the compressor.
In this arrangement of switch control 50 the
operation of the motor driven pump is automati
cally controlled so that its operation is in ac 50
ing hand wheel 31.
Hand wheel stem 36 is provided with threads
v38 engaging corresponding threads 39 in a cylin
der closing head 40, and the outer end of head 40
60 is provided with a packing member 4|. It will be
‘noted that when hand wheel 31 is turned to dis ' cordance with the temperature of the refrigerant
engage the head 35 from piston 3| and is moved in the suction line, and'in accordancev with the outwardly therefrom the rear of the head 35
conditions required the piston 3| is operated to
which'has a seating surface makes contact with a
close port 23 by valve 29 without using the
55 complementary seat 42 formed in head 40 making
hand control wheel 31, the hand control wheel
a gastight joint therewith whereby the packing being operated to its outermost position to allow
element 4| may be inserted or renewed.
piston 3| to reciprocate in its cylinder for the
Referring to Fig. 4 an operating cylinder cas
automatic operation thereof. Thus the auto
ing 32', of the same construction as shown in
matic operation of the compressor will take
60 Figure 3, is shown with a modi?ed form of piston
place irrespective of weather conditions such as
3|’ and other slight changes; with the exception’ temperature and humidity .which normally have
of these modi?cations, the parts are the same
as those illustrated in Figure 3 but the stem
36 is shown in its outer position with the head
65 35 seated in the seating surface in head 40 as
previously described. In this structure piston
3|’ is provided with a piston packing 3|b in the
form of a molded cup packing instead of piston
rings 3|a such as provided for piston 3|. This
70 cup packing is secured to piston by means of a
cup retainer 3|c. This in turn is held in place
a decided effect on the compressor capacity, and
the compressor will operate at full discharge ca
pacity or at its intermediate discharge capacity
in accordance with the control of switch 5| 65
which, as shown in Fig. 1, is controlled by tem
perature.
‘
Accordingly in the; operation of the control
mechanism when the temperature drops below a
predetermined point the switch opens and breaks 70
the current to motor 48 thereby stopping it. The
_ by a nut 3|d on the end of plunger. 30 extending . ?uid supply is consequently stopped and the fluid
through piston 3|,’ which also maintains piston in the piston cylinder is released through conduits
elements assembled on this plunger.
The cas
ing 32' is also provided with a‘closure seal 30a
43, returning by way of a check valve 53 to con
duit 44 back to the source of ?uid supply. This 75
3
2,112,791 _
allows the compressor to force valves 29 to open
position and consequently unload the com
pressor to the predetermined degree (?fty per
cent or in accordance with the position of port
22 with respect to the compressor cylinder head)
through the various ports back to the suction of
the compressor.
'
chamber surrounding the thermal bulb. This .is
for the purpose of giving a saturated tempera
ture around the bulb regardless what the super
heat temperature may be in the ‘suction line ‘
itself. Accordingly, a true saturated temperature
corresponding to the back pressure is obtained be
cause the temperature of the gas expanded must
correspond to the back pressure in the suction
line, and this true saturated temperature is ob
tained because the gas so expanded does not mix 10
with the superheated gas until it passes down to
the suction line. However when valve 64 is closed
Check valve 53 is closed by a ?uid pressurein
the conduit 43. This valve as shown in Fig. 2,
10 comprises a casing which includes an inlet port
54 and outlet port 55 which ports are connected
to conduits 43 and 44 respectively. Inside the
casing is a reciprocable valve member 55' having the capacity control of the refrigerating system
will operate in accordance with the temperature
an elongated spirally grooved passageway 56 ex
of the gas in the suction line from the evaporator 16
15 tending from its upper face to the lower portion instead of the saturated gas temperature. Thus
thereof whereby ?uid may escape from the inlet
the system may be operated under either condi
or high pressure side to the outlet or low pres
sure side when the pump is inoperative. This tion by operating with valve 64 opened or closed
.
'
valve member has a plunger 51, the end of which as desired.
It will be obviou'sto- those skilled in the art 20
seats
in
a
valve
seat
58
in
the
casing,
and
a
spring
I
20
59 therein tends to force the valve upwardly to that various changes may be made in our device
open the port through valve seat 58. In the , without departing from the spirit of the inven
upper portion of the valve casing is an abutment tion and herefore we do not limit ourselves to
what is shown in the drawings and described in
member 60 having a projection 6| thereon with
in the casing against which the movable valve the specification but only as indicated in the ap-'-"
pended claims.
..
member 55’ is adapted to engage when forced up
wardly by a spring 59. ,The position of the pro
je'ction 6| in the valve casing determines the up
per limit of the movement of valve member 55'.
A check valve 53 with modifications is shown
in Figure 5. Due to inequalities of tension of
30
' spring 59, a compensating spring 59' is positioned
above valve member 55’ and in this arrangement
the abutment member 60 with its projection is
replaced by a head 60' threaded into thecheck
valve casing in place of the member 60. This
head carries a stem 60a having a threaded en
gagement therewith at 601) and a packing mem
ber 690 forms a ?uid tight seal around stem 60a.
Stem
60a has an enlarged spring engaging mem
40
ber 6|’ on its inner end for engaging spring 59'
and its upper end is formed for receiving an op
erating tool such as a kerf 60d for receiving the
blade of a screw driver. By turning stem 60a in
vor out tension on spring 59' may be varied and
by such adjustment compensation for inequali
ties of. spring 59 is provided.
-
When the temperature rises switch 50 is‘auto-'
matically closed, starting motor 45 so that pump
48 is operated to start the circulation of ?uid
through conduit 43 to the cylinders of pistons 3|.
Check valve 53 has its valve member 55' closed
against the spring 59 by the ?uid pressure on ac
count of the resistance of the ?uid passing
through this valve. This in turn puts pressure
through the branch conduits '43 leading to the
piston chambers for each compressor cylinder
and against the pistons 3| which are forced in
.65
We claim:
'
1. In a refrigerating system, a compressor,
capacity control means constructed to operate
only during a portion of the compression stroke
for varying the volumetric displacement of the
compressor for varying the refrigerating capac-
ity of the system, and temperature responsive
means for controlling said capacity control
means, said ‘temperature responsive means being
constructed and arranged for actuation in ac
cordance with the temperature corresponding to
the pressure within the cooling element of the
said refrigerating system.
2. In a. refrigerating system, a compressor, 40
capacity control means for varying the. volu
metric displacement of the compressor for vary
ing the refrigerating capacity of the system, man
ual means for controlling the capacity control
means, and temperature responsive means for
controlling said capacity control means, said tem
perature responsive-means being constructed and
arranged for actuation in accordance with the
temperature corresponding to the pressure with
in the cooling element of the said refrigerating
system.
,
.7
3. A refrigerating system including a com
pressor, an evaporator and suction line for re
turning refrigerant from the evaporator to the
compressor and‘ capacity control means con 55
structed to operate only during a portion of the
compression stroke for varying the volumetric
displacement of the compressor for varying the
wardly and thus the ports 23 by engagement of refrigerating capacity of the system, and means
the valves 29 therewith and the compressor for controlling said capacity control means in
‘ accordance with the temperature-of expanded
then operates at full capacity.
Referring again to the thermal element 52 gas on the low side of the system.
4. A_ refrigerating system including a com-\
which cooperates with suction line l2 of the com
pressor, an evaporator andsuction line for re
pressor, it will be noted that this element is pref
erably positioned in a small chamber 62 which turning refrigerant from the evaporatonto the 65
is closed at its upper end where the thermostatic
bulb screws into it but is in open communication
at its lower end with the suction line. A small
compressor and capacity control means for vary
ing the volumetric displacement of the compres
sor for varying the refrigerating capacity of the
liquid refrigerantline G3 conducting refrigerant
system. and means for controlling said capacity '
control means in accordance with saturated gas 70
70 from receiver 16, shown connected with conduit
11, is connected with an expansion valve_64 which
in turn discharges through a connecting pipe 65
into chamber 62 around thermal element 52.
It will be noted that with valve 64 ?uid re
75 frigerant is discharged and expanded into this
temperature on the low side of the system.
- 5. In a refrigerating system, a compressor in
cluding a compression cylinder and piston there
in, capacity control means constructed to oper
ate only during a portion of the compression 75.
4
2,112,791
,
stroke to affect the volumetric displacement of
the compressor for varying the refrigerating
capacity of the system comprising a port in the
sponding to the pressure within the cooling ele
ment of the said refrigerating system.
cylinder wall and a valve for closing said port,
?uid pressure means for closing said valve, and“
cluding a compression cylinder and piston there
in, capacity control means for varying the volu
metric displacement of the compressor for vary
temperature responsive means for controlling the
supply of said ?uid pressure means.
6. In a refrigerating system, a compressor in
cluding a compression cylinder and piston there
10 in, capacity control means for varying the volu-.
metric displacement of the compressor for vary
ing the refrigerating capacity of the system com
prising a port in the cylinder wall and a valve
10. In a refrigerating system, a compressor in- 4
- ing the refrigerating capacity of the system com
prising a port in the cylinder wall and a valve for
closing said port, a ported cylinder in which said
valve is slidingly mounted, a piston reciprocably 10
mounted behind said valve and having means for
engaging said valve“ to operate it to its closed
position, a source of ?uid supply, a pump for sup
for closing said port, temperature responsive
plying said fluid behind said piston for closing
15 means for operating said valve to close the port
said valve, a conductor for returning ?uid there
from to said source of supply, and a check valve
therein operable to return the ?uid therethrough
to the source of ?uid supply when said pump is
and to permit the valve to open, and manual
control means for closing said valve, said tem
perature responsive means being constructed and
arranged for actuation inaccordance with the
20 temperature corresponding to the pressure with
in the cooling element of the said refrigerating
system.
7. In a refrigerating system, a compressor in
cluding a compression cylinder and piston there
in, capacity control means for varying the volu
metric displacement of the compressor for vary
ing the refrigerating capacity of the system com
inoperative.
11. In a refrigerating system, a compressor, 20
capacity control means for varying the refrigerat
ing capacity of the compressor, a ?uid supply
source, means for placing the ?uid under pressure
for operating said capacity control means to cause
the refrigerating system to operate at full 25
capacity, _a conductor for returning ?uid there.
from to said source of supply, and a check valve
prising a port in the cylinder wall and a valve
therein operable to return the ?uid therethrough
for closing said port, temperature responsive
to the fluid supply source when said ?uid pressure
means is inoperative.
80
12. In a refrigerating system, a compressor
means for operating said valve to close said port
and to permit the said valve to open said port,
and manual control means for operating said
valve including a stem movable inwardly toward
said valve to effect the engagement of said valve
with said port in its closed position and mov-e
able outwardly away from said valve to release
the valve from the effect of said manual control
means.
8. In a refrigerating system, a compressor in
with ?uid pressure operated capacity control
means, a source of ?uid supply and means for
supplying ?uid therefrom under ‘pressure to said
?uid pressure operated control means, a con
ductor for returning ?uid from said control means
to said source of supply, and a check valve there
in for unloading the operating ?uid and returning
it to the source of ?uid supply when the pressure
cluding a compression cylinder and piston there
thereon is reduced.
in, capacity control means for varying the volu—
metric displacement of the compressor for vary
ing the refrigerating capacity of the system com
prising a port in the cylinder wall and a valve
for operating said port, manual control means
for closing said valve including a stem movable
inwardly toward said valve and outwardly away
13. In a refrigerating system, including a com
pressor with ?uid pressure operated capacity con-'
trol means, a source of ?uid supply and means
for supplying ?uid therefrom under pressure to
said pressure operated control means, a conductor
for returning ?uid from said control means to
said source of supply, and a check valve therein for
from said valve, a head on one end'of said stem
arranged on one side to.form a control valve,
unloading the operating ?uid therethrough com
a control cylinder head with a packer through
which said stem operates, and said control cyl
inder head having a cooperating valve seat adapt
ed to receive said control head valve and form
a seal therewith when the stem is in its outer
most position.
9. In a refrigerating system, a compressor in
cluding a compression cylinder and piston there
in, capacity control means constructed to oper
ate only-during a portion of the compression
stroke for varying the volumetric displacement
of the compressor for varying the refrigerating
capacity of the system comprising a port in the
cylinder wall and a valve for closing said port,
a source of ?uid supply, ?uid pressure means
65 for closing said valve, and means for controlling
the supply of said ?uid pressure means, and
means for returning the ?uid directly to the
?uid supply source when the pressure of the ?uid
70 pressure means is reduced so as to permit the
valve to open by the pressure in the compressor
and thereby cause the compressor to operate at
lower capacity, said temperature responsive
means being constructed and arranged for actua
tion in accordance with the temperature corre
40
prising a valve casing having a cylindrical interior
and inlet and outlet ports at opposite ends there
of, a valve member therein operable to close the
communication with the outlet port, said valve
50
including‘ a piston portion’ slidable in said casing,
a spring under said valve member tending to move
it from itsv closing position, and said piston por 55
tion having a restricted passageway therethrough
permitting the passage of ?uid therethrough
when the pressure of the ?uid is reduced.
14. In a refrigerating-system, including a com
pressor with ?uid pressure operated capacity con 60
trol means, a source of ?uid supply and means for
supplying ?uid therefrom under pressure to said
pressure operated control means, a conductor for
returning ?uid from said control means to said
source of supply, and a check valve therein for.
unloading the operating ?uid therethrough com
prising a valve casing having a cylindrical in
terior and inlet and outlet ports‘ at opposite ends,
thereof, a valve member therein operable to close
the communication with the outlet port, said valve 70
including a, piston portion slidable in said’v cas
ing, a spring under said valve member tending
to move it from its closing position, a spring over
said valve tending to move in the reverse direc
tion, means for adjusting the tension of the last
2,112,791
said spring, and said piston portion having a re
stricted passageway therethrough permitting the
passage of ?uid therethrough when the pressure
of the ?uid is reduced.
15. In a refrigerating system, a compressor,
capacity controlling means constructed to operate
only during a portion of the compression stroke
5
of said compressor for varying the refrigerating
capacity of the system, and temperature re-v
sponsive means for controlling said capacity con
trolled means.
NORMAN M. SMALL.
LEON BUEHLER, JR.
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