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Патент USA US2294552

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Sept l, 1942.
i E__ GYGAX.
Original Filed May 15, 1937
2 Sheets-Sheet 1
// .
r‘lq 5/
n 43
Sept. l, 1942.`
Original Filed May 13, -1937
2 Sheets-Sheet 2
Patented Sept. l, 1942
~rNr orFlcs
Ernest Gygax, St. Louis, Mo., assigner to Curtis
Manufacturing Company, Wellston, Mo., a cor
poration of Missouri
Originail appiication ll’liay 13, 1937, Serial No.
142,395. Divided and this application Septem
ber 26, 1939, Serial No. 296,636
3 Giaims.
cant will be forced from the compressor having
This invention is a division of my pending
the higher crankcase pressure to the compressor
application, Serial No. 142,395, ñled May 13, 1937.
having the lower crankcase pressure.
Said application has matured into Patent No.
It is, therefore, another object of this inven
tion to provide a condensing unit having dual in
This invention relates to refrigerati-ng systems
terconnected compressors with a means to insure
and controls.
a safe oil level in both compressors at all times.
An increasingly large number of refrigerating
In various installations, for example, in air
systems are subject to varying loads on the evap
conditioning installations, the temperature to
orating coils. In such installations, the amount
which the evaporator is exposed varies and after
of refrigerant which is evaporated in the evap
a shutdown of the system, a rather high positive
orating coils may vary considerably during short
pressure exists in the compressor suction line.
periods of operation of the apparatus. This is
This makes it very difficult to start the Com
especially true of air conditioning installations
pressor after a shutdown period and often results
where the variance of the load on the evaporating
coils may be appreciable. If the load on the 15 in the stalling of the driving motor.
It is an object of this invention to provide a
evaporating coils, that is, their capacity to evap
device to ease the starting load of refrigeration
orate refrigerant, becomes less than the capacity
of the compressor and condenser to condense re
The above and other objects will become appar
frigerant, liquid or partially liquid refrigerant
will be drawn into the compressor crankcase and 20 ent from the following detailed description and
accompanying drawings of my invention. In the
produce serious damage to the compressor be
accompanying drawings:
cause of freezing of the lubricant and locking of
Figure 1 is a diagrammatic view of a portion of
the pistons. It is necessary, therefore, that the
a condensing unit embodying some of the con
load or capacity of the evaporating coils or evap
trols of this invention.
orator be balanced with respect to the capacity
Figure 2 is a diagrammatic view of a portion of
of the compressor or condensing unit.
a condensing unit provided with other controls
Two compressors supplying a common load are
of this invention.
often connected to the same suction line, powered
Figure 3 is a view showing an arrangement of
from the same motor and mounted on the same
base along with other equipment to form a con 30 controls to ease starting loads.
Figure 4 is a detailed view of one type of oil
densing unit. It is often necessary to balance
equalizing valve.
the output of such a condensing unit with the
Referring now to the drawings in which the
capacity of the evaporator at any particular time.
same numerals are used throughout to denote the
The above is accomplished in the present in
vention by the insertion of a modulating or choke 35 same or similar parts: l indicates a driving motor
equipped with a pulley 3 and driving compressors
valve in the suction line of one of the com
5 and 'l through belts 9. Each compressor has
pressors, and controlling it by the condition of
its suction, intake, or inlet, side connected to a
the refrigerant in the common suction line of the
common suction line l l through passages or pipes
condensing unit, in a manner yet to be described.
When such a system is used to control the ca 40 i3 and l5. The outlet of each compressor is con
nected to an oil separator Il by lines I9. A line 2|
pacity of a condensing unit and under certain
may connect with a refrigeration condenser, of
other conditions of compressor operation where
any of the many types known in the art, which is
two compressors are interconnected, it is neces
not shown in the drawings. An oil return line
sary to provide a means to insure that both com
pressors will retain a sufñcient supply of lubricant 45 23 connects the oil separator with the crank
cases 25 and 21 of the respective compressors.
in their respective crankcases to maintain satis
One form of oil equalizing device is shown in
factory operation. This is often attempted when
Figure 1 in which an oil equalizing line 29 con
two compressors are connected to a common suc
nects with the crankcases of each compressor
tion line and each provided with an oil separator
in the outlet, by providing an oil equalizing line 50 and has a valve 3| inserted therein, the function
of which will presently be described. Outlets 32
between the compressor crankcases to equalize
to the equalizing lines may be placed above the
the oil level therebetween. When, however, a
safe oil level in the orankcases. Lines 33 and 35
difference exists between the pressure in the
communicate the pressures in the respective
crankcases of the respective compressors, such a
line will not function properly as all of the lubri 55 crankcases of the compressors to this valve. n.
detailed view of this valve is shown in Figure 4.
tion line. Thus in normal operation, refrigerant
A modulating or choke valve 3l!` may be inserted
in the suction inlet connection to one of the com
pressors and has a line 39 communicating with
from the evaporating coils is drawn» through the
common suction line II and through the pas
the common suction line II.
This valve is of a
type well known in the art which closes when the
pressure made available to it by the line 39 de
creases below a predetermined Value and opens
again when the pressure increases above a prede
termined Value. The valve 3l is of a type which
will open when the pressures communicated to it
by the lines 33 and 35 are substantially equal but
will close when a predetermined difference in
pressure exists between the lines 33 and 35. This
valve may comprise a body portion 49 in which
the oil lines 29 may be inserted. A piston 42 may
slide in an opening or bore 44. A passage 46
cooperates with passages 43 in the body portion
to allow oil or other ñuid to pass through the
valve when it is in the position shown. The
pressure in the respective compressor crankcases
is communicated to the chambers 52 and 54 by
the lines 33 and 35. The chambers may be
sages I3 and I5 to the compressors to be com
pressed and delivered through the lines I9, the
oil separator I 1 and line 2| to a condenser where
the refrigerant is condensed after which it passes
to the evaporating coils to be evaporated. If
the load on the evaporating coils is not sufli
cient to evaporate all of the refrigerant, the pres
sure in the common suction line will fall and
cause the moderating valve 31 to close in accord
ance with the pressure communicated to it
through line 39 and thus reduce the flow of re
frigerant into the compressor 5 which in turn
will reduce the output of the condensing unit until
the evaporating coils evaporate all the refrig
erant which they receive and the pressure in the
common suction line returns to normal.
It is obvious that such a control is very sensi
tive and accurate and will maintain a balance
between the condensing unit capacity and the
load on the evaporating coils even though the
load may vary appreciably during short periods
closed by plates 55 against which springs 58 may
press to maintain the piston by acting against 25 of time.
In Figure 2 the moderating or choke valve is
rods 69. It can be seen that when the pressures
controlled by the temperature within the com
at the opposite ends of the valve piston are equal,
mon suction line. Thus when the evaporating
the valve passages will meet and allow oil to pass
coils do not evaporate all of the refrigerant pro
but when the pressure on one side of the piston is
duced by the condensing unit, the temperature
different from that on the other side, the passages
will not be in line due to movement of the piston
and will effectually prevent any ilow of oil
within the common suction line will fall due to
the evaporatoin of some of the unevaporated re
frigerant. The valve 4I- is arranged to close
when the temperature in the common suction
for the actuation of the moderating or choke 35 line decreases below a predetermined value and
hence a decrease in temperature by causing this
valve by thermal means instead of pressure
valve to close will cause a reduction in the input
means and the moderating valve 4I there indi
to the compressor 5 which will decrease the out
cated is of a type well known in the art, which
through the pipes 29.
The arrangement shown in Figure 2 provides
put of the compressor enough to allow the evap
will close when the temperature communicated
to it decreases below a predetermined point but 40 orating coils to become balanced with the con
densing unit.
will open again when the temperature communi
Either of the modulating valves 31 or 4I need
cated to it increases above a predetermined point.
not be located at the precise point shown; they
The temperature may be communicated to the
may for instance be located on or in the com
valve by a tube 43 containing an eXpansible liq
pressors if desired and control the capacity of
uid and a line 45.
the suction inlet thereto. The function of these
In Figure 2 a slightly different method of
valves is to regulate the compressor capacity by
controlling the oil flow in the equalizing line has
changing the compressor intake opening.
been provided in the form of a reservoir 41, a
In compressors where the suction inlet is made
float valve ¿59 and associated float 5t. It should
>to the compressor crankcase it is obvious that the
also be noted that the line from the crankcase of
pressure in the crankcase of the compressor pro
compressor 5 extends to a low level in the reser
vided with the moderating valve on its intake side
voir 41. A pressure relief valve 5I is placed in a
will vary with the opening and closing of this
line 53 which enters the reservoir and the crank
valve. When the valve chokes or reduces the
case above the oil level. This valve 5| is of a
suction inlet .the pressure will decrease in the
well known type arranged to allow passage of a
crankcase while an increase in pressure will iol
gas in one direction only, in this case, from the
low the opening of the moderating or choke
reservoir to the crankcase. The safe oil level in
each compressor is indicated by the line 55 and
When the moderating valve is open and both
the high oil level by a line 51 in the drawings.
The operation of the choke valve or moderat G0. compressors are operating normally any oil which
is present-l in the refrigerant leaving the com
ing valve will first be described. As previously
pressors will be caught in the oil separators I1
stated, it is necessary to control the output of
and returned to the respective compressor crank
the condensing unit in accordance with the load
cases through lines 23. The oil in the respective
on the evaporating coils so as to prevent liquid or
crankcases may flow through the line 29 to equal
partially liquid refrigerant from being drawn in
ize the oil level in the crankcases. It can be
the refrigerator compressors through the suction
seen that if the valve 3| were not in the line 29,
lines. Such control is necessary with a dual
oil would flow from the crankcase 21 to the
compressor condensing unit as shown in the Fig
crankcase 25 when the moderating valve 31 was
ures 1 and 2 and is accomplished in this inven
tion by inserting a moderating or choke valve 70 closed, due to the decrease in the pressure with
in the crankcase 25. Eventually all the oil in
in the suction inlet to one of the compressors
and controlling the action of this valve by the
the crankcase 21 above the level 55 would be
physical conditions of the refrigerant returning `
forced into the crankcase 25 after which refrig
to the compressors. In Figure 1 the valve shown
erant could be drawn through the line 29 from
is operated by the pressure in the common suc 75 the crankcase 21 to the crankcase 25 and com- `
pressor 5. Such operation would defeat the pur
pose of the moderating valve 31 and makes the
use of a valve similar to the valve 3| desirable.
The valve 3| is interposed in the line 29 and may
have pressure lines 33 and 35 communicating
with the pressure in each of the compressor
crankcases. The valve is arranged so as to open
only when the pressures within the compressor
crankcases as communicated to it by `the lines 33
and 35 are substantially equal. Thus when the
moderating valve is open and the pressures with
same function as this valve. The 'valve may
comprise a body portion 12 provided with an
upper chamber 14 and a lower annular chamber
16. A valve seat 18 cooperates with a valve face
or washer 89 which is secured to a piston 82. The
piston operates in a cylinder bore 84 and is se
cured to a rod 86 which may pass through a bush
ing 88 and packing 90 to be secured to a bellows
92 through a plate 94. A gas tight cover 96 en
closed the bellows and is secured to the body por
tion of the valve. A connection 98 allows a pipe
|99 to be connected thereto by a nut |02. The
in the compressor crankcases are substantially
pipe |00 may be connected to any portion of the
the same, the valve 3| will be open and allow the
suction line between the valve and the evaporat
oil level in the two crankcases to become equal
ized. When, however, ,the pressures in the two 15 ing coils or may be connected directly to the
proper side of the valve itself as shown in this
crankcases become unequal, due to the operation
drawing by a connection |94. The valves 31 and
of the moderating valve, the valve 3| will close
«il in the Figures l and 2l show a line 39 and 45
andthe unsatisfactory cycle of operations above
respectively which are similar to this line and it
outlined will be prevented.
In Figure 2 is shown an optional method of 20 is obvious that the line as here shown could be
connected as there shown or those lines could be
controlling .the iiow of oil or lubricant from one
connected as this one is.
crankcase or lubricant reservoir to another.
An adjustable stop for the piston may be pro
When the moderating valve 4| is open and the
vided by a rotatable rod |06 provided with a por
pressures in the compressor crankca-se substan
tion |93 suitable to be turned by a properly de
tially equal, the lubricating oil is free to flow
signed key or wrench. The rod |95 passes
from one crankcase to the other through the
through a packing nut HU, packing ||2 and
reservoir d1. The level of the lubricant in the
bushing IIB. A threaded portion H6 acts with a
reservoir 41 will depend upon the elevation or
cooperating stationary threaded portion ||8 to
position of the reservoir with respect to the two
give the rod vertical movement when it is rotated.
crankcases. When the moderating Valve ¿il
An end of the rod |20 which may be cylindrical
closes and the pressure within the crankcase of
in shape and oscillate in the sleeve | 2|, may be
the compressor 5 is thus decreased, oil will flow
provided with a washer |22 secured thereto as
from the crankcase of the compressor 1 through
by a screw IZA against which the portion |25 of
the reservoir s1 and into the crankcase of the
the piston may abut. A cap |39 covers the end
compressor 5. This flow cf oil will continue until
of the rod. Thus it can be seen that by rotating
the oil in the compressor 1 is reduced to the level
the rod |05, the distance through which the pis
55 when due to the position of the outlet to the
ton 82 moves may be adjusted to vary the valve
line 29 no more oil will flow but any further flow
opening, A chamber |32 below the piston com
will be of refrigerant from‘the crankcase af the
compressor 1. The refrigerant will flow into the 40 municates with a passage |34 into which a line
|35 may be inserted and secured as by a nut |31.
reservoir 41 and force oil from this reservoir into
The numeral |35 indicates a drain plug which
the crankcase of the compressor 5 until the level
may be desirable. The line |35 communicates
of the oil in the reservoir allows the float 59 to
with a solenoid valve |39.
fall and close the line 29 from compressor 1 by
This valve is of the usual type and will not be
the valve 49. By this arrangement, a safe oil 45
described in detail except that the passage be
level is insured in each compressor and the re
tween the line |35 and a line Ilil is open when
frigerant from the compressor 1 cannot flow into
the valve stem |53 is raised by the passing of an
the suction side of the compressor 5. When the
electric current through solenoid coil |145. The
moderating valve is opened and the pressures
leads |651 and |49 from this coil pass to a cur
within the crankcase become substantially equal .
rent supply through a switch |59. The current
again, oil will be forced from the crankcase of
supply is connected to the motor line of the com
the compressor 5 back into the oil reservoir. The
pressor of the refrigeration system which is being
gas or refrigerant which was in the reservoir can
controlled so that the solenoid valve will be in
flow back through the line E3 and valve 5|, which
operative unless the compressor motor is switched
allows it to pass only one way, that is, into the
on. The switch |59 is of a type which is oper
crankcase of the compressor, to release the gas
ated by pressure communicated to it by line |52
pressure from the reservoir 41. This permits oil
which connects to the compressor suction line be
from the crankcase of the compressor 5 to raise
tween the valve 10 and the compressor. The
the oil level in the reservoir ¿i1 which in turn
opens the iioat valve and allows the oil to flow 60 switch is arranged so that when the pressure
communicated to it exceeds a predetermined
back to the crankcase of the compressor 1.
value, it will close the circuit to operate the
Referring now to Figure 3, the numeral 19 in
solenoid valve.
dicates a special valve which may have a throt
If the special valve 19, switch |50, and solenoid
tling or modulating control section somewhat like
the valve 31 or a temperature control section sim 65 valve |39 are connected as described above and
properly adjusted, a compressor can be started
ilar to the valve lil, and a piston controlled sec
up on a refrigeration system which has become
tion which will be described. This valve, when
warm without overloading or stalling the motor
used with dual compressors, may be located in
due to the abnormal back pressures present.
the line where valves 31 or 4| are located in Fig
The valve 1U as shown in Figure 3 incorporates
ures 1 and 2 respectively. If used on only a sin 70
the throttling portion, i. e., the part controlled
gle compressor, the valve may be located on the
by the bellows along with the piston portion
suction line. A valve which has been used and
which is necessary to ease the starting load. The
found to give satisfactory results is shown in Fig
throttling portion operates similarly to the valve
ure 3 although it will be apparent that other
types of valves may be designed to perform the 75 31 previously described. When the pressure in
the suction line between evaporator 'and the valve
drops too low, the bellowsy moves rthe facev 80
against the seat 78 by raising the rod 85, thus
maintaining a constant suction pressure and
bringing about'the generaly results obtained by
use of the valve 31 previously described.
Ob- ,
viously the bellows section could be interchanged
with a thermostaticr sectionfsimilar yto the ther
I claim:
1. In a device for insuring a safe oil level in
each of the crankcases of a plurality of intercon
nected compressors, an oil reservoir, a fluid pas
sage between said' oil reservoir and each of the
crankcases'of the compressors, each of the said
fluid passages having'one of its ends in communi- '
cation with the oil reservoir and its other end eX
mostatic valve 4| previously described and ther
te'nding' intoy the crankcase yof one of the intercon
nected compressors, said end of the iiuid passage
that extends into the crankcase of one of the
thestarting load, however, and its operation is
compressors rbeingfpositioned ra short distance
as follows:
above the bottom of the said crankcase, and being
After a refrigeration systemhas been idle for
adapted to cooperate ywith the crankcase to
a time and the temperature of the coilsfand lines 15 maintain a safey oily level in the bottom of the
allowed to rise, the pressure of the refrigerant
crankcase at all times, and meansy responsive tor '
results would be the same. The piston portion
vrof the valve yisy the part which rserves to ease
o inthesuction line increasesand sometimes to
the level of theY contents in the oil reservoir to Y
such an extent, depending, of course, on the tern
vary the passage of a fluid through one of said
perature, that it is diñicult to start the com
fluid passages.
pressor due to theincreased back pressures on the 20
2. In a device for insuring ya sato oil level in
each of the crankcases of a plurality of inter
Such diñiculties are often encounteredin air
connected compressors, an oil reservoir, a fluid
conditioning systems when ,ther system may be
passage between said oil reservoir and each of the
shut down over night and restarted during the
rcrankcases of thecompressors, each of the fluid y y
day. If these Valves are connected to the system 25 passages having one of yits ends in communica
as described, a high pressurein the suction line
tion with the oil reservoir and its other end ex
|3 will be communicated tov the switch |58 by the ' ' tending into the crankcase of one of the intercon
line I 52. This high pressure will close the switch
nected compressors, said end of the ñuid passage
{5l}J and if thefmotor line is closed, the lines I 41
vthat extends into the crankcase of one of the
and |49 will be energizedfto open the solenoid 30 compressors f being positioned a , short distance
valve | 39. This allows positive pressurer from the
above the bottom of the said crankcase, and being
ccmpressorfoutlet toy ,be ycOrrlrnurlicated to the
adapted to 'cooperate with the crankcase to main
chamber |32 through lines I4! and |36.,r Pres
tain a safe oil levelin the bottom of the crank
sure in the chamber |32 will cause the piston to
case at all times, means responsive to the level '
rise and close the valve face 80 against the seat 35 of the contents in the oil reservoir to vary the
passage of a fluid through one of said fluid pas
Briefly, a high pressure in the suction line will
sages, said means being arranged to permit the'V
f close the line when the compressor motor is
flow of fluid through the fluid passages when
started. The closing ofthe suction line will allow
ever the levelof the oil in the oil reservoir is
the compressor to start without the heavy load 40 above a predetermined level, and to halt 'the'ñow
of the back pressure. As soon as the compressor
of fluid throughy the one iluid passage whenever
reduces the back pressure in the suction line, the
the level of the oil in the oil reservoir falls to
switch |50 will open, closing the solenoid valve
the predetermined level, and a pressure relief
and allowing the valve face 80 to recede from its
passage to allow the passage of a gas from the
seat until the pressure rises too high again.
45 oil reservoir to one of the compressor crankcases.
I have thus provided a device which allows the
starting load on a refrigeration compressor to be
appreciably reduced. This will obviate the neces
3. A lubrication system for a plurality of re
frigeration compressors, including a lubricant
reservoir, a passage between the crankcase of each
sity of special motors and electrical equipment
of said compressors and the reservoir, said pas
and will add to the life of refrigeration equip 50 sage having one end in communication with the
ment being used.
oil reservoir and its other end extending into the
It is obvious that the various controls may be
crankcase of one of the compressors, said end of
variously combined to meet any particular condi
the passage that extends into the crankcase of
tion desired. Thus either type of throttling sec
the compressor being positioned a short distance
tion could be used with either type of oil equaliz 55 above the bottom of the said crankcase, and being
ing valve and either with or without the unload
adapted to cooperate with the crankcase to main
ing section. The number of compressors might
tain a safe oil level in the bottom of the crank
also be one, two or more, depending on the par
case at all times, a valve means to shut oiî one
ticular system used.
of said passages when the level of a lubricant
While I have described but several embodiments 60 in the lubricant reservoir recedes below a prede
of my invention. it will be apparent to those
termined level, and a pressure relief conduit to
skilled in the art that Various modifications, addi
permit gas to flow from the reservoir to one of
tions, substitutions, and omissions may be made
the compressor crankcases.
in the embodiments shown without departing
from the spirit and scope of the invention as de 65
ñned in the appended claims.
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