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Патент USA US3091954

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June 4, 1963
D. VAN DEN BERGE ETAL
3,091,944
HEAT PUMP SYSTEM
Filed Oct. 31. 1961
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I N V E N T 0R S
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A T T O R N E Y S
United States Patent 0 ” C6
1
3,091,944
Patented June 4, 1963
2
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clearly apparent as the speci?cation proceeds to describe
the invention with reference to the accompanying draw
ings in which:
3,091,944
HEAT PUMP SYSTEM
Dick Van Den Barge and Robert G. Miner, both of La
FIGURE 1 is a schematic representation of a refriger
Crosse, Wis, assignors to The Trane Company, La
Crosse, Win, a corporation of Wisconsin
Filed Oct. 31, 1961, Ser. No. 149,076
4 Claims. (Cl. 6ZP-197)
ation system incorporating the invention in the preferred
embodiment; and
FIGURE 2 schematically represents another form of
the invention. ‘
FIGURE 1 shows the preferred embodiment of the in,
This invention relates generally to a heat pump refrig
crating system and more particularly to a heat pump re 10 vention incorporated in a refrigeration system including
a compressor 10, an outdoor heat exchanger 12, a receiver
trigeration system which incorporates a high ‘side pres
14, expansion means 16 ‘and 17, and an indoor heat ex
sure control when the temperature of the coolant passing
changer 18. Expansion means 16 and 17 are shown as
over the heat exchanger acting as a condenser is below
expansion valves responsive to suction, but obviously
that necessary for proper operation ‘of the expansion
means.
15 other expansion devices may be used without departing
In recent years, the ‘air conditioning industry has had
serious problems in the use of air conditioning equipment
Where the temperature of the cooling ?uid, employed as
the heat absorbing medium for the heat exchanger acting
as a condenser, is abnormally low. The employment of
such low temperature heat absorbing medium results in
a drop in high side pressure below a predetermined level
from the scope of the invention. A tour vvay reversing
valve 20 of any conventional construction is connected
between the heat exchangers 18 land 12. A high pressure
cut-out 22 is connected to discharge line 24 to stop the
compressor 10 in case of unusually high ‘discharge pres
sures. A low pressure cut-out 26 is connected to suction
conduit 28 to stop the operation of compressor 10 in case
of unusually low suction pressures.
causing a reduction in the useful capacity of the ‘heat
On the normal cooling cycle hot uncondensed refrig
exchanger acting 'as ‘an evaporator due to inadequate op
erating pressures at the expansion means. The solution 25 erant will pass through conduit 24, reversing valve 20,
conduit 30 to the outdoor heat exchanger 12 :and be con
to the problem naturally entails raising ‘or maintaining
densed therein. Liquid refrigerant from heat exchanger
the high side pressure. Basically, this is done by ?ooding
12 will then ?ow to receiver 14 through conduits 32 and
or reducing the effectiveness of the heat exchanger ‘acting
34, check valve 36, conduits 38 and 4-0, and three Way
as a condenser when the high side pressure ‘falls below
pressure responsive valve 42. From receiver 14 liquid
a predetermined minimum.
refrigerant ?ows through conduit 44, check valve 46',
In the normal heat pump operation employing air [on
both the heat exchangers the above problem is prevalent
on both the heating and cooling cycles. On the cooling
cycle when the temperature of the condensing medium
is below that desired the evaporator does not perform the
cooling performance required to maintain proper com
fort conditions in the conditioned space. On the heating
cycle the heat exchange medium being heated by the heat
exchanger acting as a condenser is normally of 1a very
low temperature causing insu?icient pressure at the ex
pansion means resulting in premature icing of the heat
exchanger ‘acting ‘as an evaporator and in stopping of the
conduit 48, expands through expansion valve 16, passes
through conduits 5i} and 52, absorbs heat from the air
to be conditioned in the indoor heat exchanger 18 ‘and
returns to the compressor 10 through conduit 54, reversing
valve 20, and conduit 28.
‘ On the normal heating cycle, the position of reversing
valve 2b is reversed and hot uncondensed refrigerant is
delivered to indoor heat exchanger 18 through conduits
24 and 54 where the refrigerant is condensed ‘and gives
up heat to the heat exchange medium passing through
the heat exchanger. Condensed refrigerant then flows
to receiver 14 through conduit 52, check valve 56, con
compressor on low pressure cut-out due to low ‘suction
duits 53 and 4t), and three way pressure responsive valve
pressure.
45
It is, therefore, an object of the invention to provide
automatic control of the head or high side pressure in a
42. Liquid refrigerant from the receiver flows through
conduit 6i), check valve 62, conduit 64, ‘expands through
heat pump system by ?ooding the heat exchanger acting
expansion valve 17 and passes into the outdoor heat ex
changer 12 via conduitsds and 32 wherein it ‘absorbs
vas a condenser in response to high side pressures.
Another object of the invention is to provide a hot gas 50 heat from the heat exchange medium passing over the
heat exchanger. The vaporized re?riger-ant is then re
bypass conduit ?om the compressor ‘discharge line to the
liquid line between the condenser and receiver and to
turned to the compressor via conduit 3%, reversing valve
provide pressure responsive means in the bypass conduit
20, vand suction conduit 28.
‘and in the condenser outlet conduit to control the effec
Three way pressure responsive valve 42 consists of
tive condensing surface of the condenser.
55 casing 70, inlet port 72 connected to hot ‘gas bypass line
A third object ‘of the invention is to provide a heat
74, inlet port 76 connected to liquid line 40, and outlet
pump refrigeration cycle with a hot gas bypass conduit
port 78 connected to receiver 14. A ?exible diaphragm
extending from the compressor discharge line to the liquid
89 of metal or other suitable material is secured to casing
line and bypassing the condenser 1a'nd to provide a pres
70 and moves valve head 82 between valve ports 84 and
sure responsive valve at the junction of the hot gas by 60 86, depending on the pressure in chamber 88 acting against
pass conduit and the liquid line to automatically maintain
the proper high side pressure at low ambient coolant
temperatures.
A still further object of the invention is to provide a
the force ‘of spring WP. Screw member 92 is provided
for adjustment of the compression of spring 90.
Under either the normal heating ‘or cooling operation
of our improved heat pump cycle when the heat exchange
heat pump refrigeration cycle with hot gas bypass conduit 65 medium passing over the heat exchanger acting as a
from the compressor vdischarge line to the liquid line ‘and
bypassing the condenser and to provide pressure respon
sive valves in the hot gas bypass conduit ‘and in the liquid
line between the condenser ‘and the junction of the bypass
conduit and the liquid line to control the high side pres 70
sure.
Other objects ‘and advantages of the invention will be
condenser is above a predetermined minimum tempera
ture, 'hot uncondensed refrigerant will pass through con
duit 74 into chamber 88 of pressure responsive valve 42
and act ‘against diaphragm '80 and spring 90‘ to move
valve head 82 to the left and thereby close valve port
84 and open port 86. As described hereinbefore the
liquid refrigerant from either indoor heat exchanger 12‘
3,091,944.
3
4
or outdoor heat exchanger, depending on whether the
system is in the heating cycle or cooling cycle, will then
pass through conduit 40 and three way pressure respon
sive valve 42 and into the receiver from either conduit
for proper operation of the expansion means. When
the high or normal temperature air is passing over the
heat exchanger acting as a condenser, the high side pres
58 or conduit 38.
'
‘
Assume for discussion purposes that the heat exchange '
medium passing over the indoor heat exchanger 18 is
primarily air recirculated from the area ‘being condi
tioued and the heat exchange medium passing over the
outdoor heat exchanger is ambient air. It can readily
be seen that when the refrigeration system is in opera
tion on the normal cooling cycle there will be periods
when the ambient air temperature will be lower than that
required for proper condensing. This naturally will re
sult in reduced pressure at the expansion valve IG'the-reby
reducing the effective capacity of the heat exchanger 18.
Cl
sure ‘will increase to the proper operating pressure and
valve port 84 will be closed by the pressure transmit
ted to chamber 88 by conduit 74 and the liquid from
the heat exchanger acting as a condenser will pass into the
receiver 14 and the system will resume normal operation.
Modi?cation 0]‘ FIGURE 2
Looking now to FIGURE 2, there is shown a modi
?ed form of the invention. The basic refrigerant com
ponents shown in FIGURE 1 will be denoted by the
same reference numbers in FIGURE 2. Instead of hav
ing a single three Way pressure responsive valve con
nected to ‘the hot gas bypass conduit 74 and to‘ the liquid
Conversely, when the refrigeration system is operating
line 40, I have provided a pressure regulating valve 94 in
on the heating cycle, a problem is encountered on start-up
the hot gas bypass conduit 74 and a back pressure valve
96 in the liquid line 40‘.
since the recirculated air is cooler than desired resulting
in reduced condensing temperatures across the indoor heat
Pressure regulating valve 94 and back pressure valve
exchanger causing reduced effectiveness of the outdoor
96 are similar in construction in that each valve has a
heat exchanger 12. This reduced effectiveness of the
casing 98, a diaphragm 100 secured to the casing 98, a
outdoor heat exchanger 12 resulting in cutting off the
spring 10-2 with adjusting nut 104 exerting pressure on
compressor on low pressure cut-out and constant revers
diaphragm 100, valve stem 106 attached to the diaphragm
ing of the refrigeration cycle to defrost the outside heat 25 100, and with a valve head 108 attached .to valve stem
exchanger 12 because of premature icing. Both the cut
106. Valve 94 differs from valve 96 in that a rise in
ting out of the compressor and constant reversing of the
pressure will close valve 94 but will open valve 96. This
reversing valve 20 result in excessive wear on the com
is accomplished by locating the valve head 108 of valve
ponents of the system and very slow heating of the space
to be conditioned. “Our improved heat pump refrig
eration cycle provides high side pressure control on both
the heating and cooling cycles to alleviate the above men
94 on the outlet side of the valve port 110. Note valve
96 where the valve head 108 is on the inlet side of valve
port 112.
In normal operation when the air temperature is suffi
tioned problems.
ciently high to maintain proper operating pressures, the
As indicated above, control of head pressure is neces
sary on ‘both the heating and cooling cycles. Our new
and improved high side pressure control is effective on
discharge pressure will act on diaphragm 100 of pressure
regulating valve 94 ‘and maintain valve head 108 against
valve port 110- to shut off the passage of hot gas ‘from
the conduit 74 to the receiver 14. At the same time,
both the heating and cooling cycles. Basically our con
trol will‘ ?ood the outdoor heat exchanger 12 on cool—
ing when the ambient air temperature is below a prede
the pressure in the liquid line 40 will act on the dia
phragm 100 of back pressure valve 96 to maintain the
termined minimum or will ?ood the indoor heat ex 40 valve head 108 away from the port 112 against the ac
changer 18 on the heating cycle when the recirculated
air temperature is below a predetermined minimum.
Operation-FIGURE 1
tion of the spring 102. To refrigerant will pass con
secutively through discharge conduit 24, the heat ex
changer acting as a condenser, back pressure valve 96,
receiver 14, expansion valve, heat exchanger acting as
Assuming that either one or the other of the above 45 an evaporator, and back to the compressor 10 through
adverse conditions exist and control of high side pres
suction line 28.
sure is necessary, the refrigeration system will automati
As the high side or head pressure decreases, the dia
cally flood the heat exchanger acting as a condenser. Due
phragm 180 of valve 94 will start to open valve port ‘110
to one or the other of the above mentioned adverse con
by moving valve head 108 to the right. If the high side
ditions the high side pressure will be reduced causing a
reduction of operating pressure at either expansion valve
16 or expansion valve 17 depending on whether the sys
tem is heating or cooling. The pressure in hot gas by
pressure continues to decrease, the valve head 108‘ of
valve 94 will move to a position where valve port 110' is
completely open. The tensions on springs 102 are set
Therefore the liquid condensed in the heat exchanger
the high side. pressure drop.
so that the pressure regulating valve 94 will open com
pass 74 will also be reduced and the spring 90 in con
pletely on decreasing pressure and then after a further
junction with the diagram 80 will move valve head 82 55 decrease of pressure, the back pressure valve 96 will start
to the right, opening valve port 84 and throttling valve
to close. As in the modi?cation of FIGURE 1, back pres
port 86. This has a twofold effect on the system. First,
sure valve 96 will throttle the conduit 40 which provides
liquid will back up in the heat exchanger acting as a
communication between the heat exchangers and the re
condenser decreasing the effective condensing surface and
ceiver, when the head pressure is low. This will cause
causing an increase in head pressure. This is accom 60 condensed liquid to back up in the heat exchanger acting
plished since little or no liquid can flow to the receiver
as a condenser. This modi?cation is completely auto
14 through conduit 40 because ‘of the throttling effect of
matic and is operated directly from the pressures in the
valve head 82 on valve port 86 of three way valve 42.
system in order to flood the condenser in accordance with
On increasing pressure, the
acting as a condenser will accumulate in the heat ex 65 above operation will be reversed and the back pressure
changer causing the head pressure to build up. Secondly,
hot gas from the bypass 74 will pass into the receiver
valve 96 will ‘be completely open before the pressure
regulating valve 94 starts to close.
14 by way of valve port ‘84- and thereby warm the re
It can readily be seen that we have provided a new and
frigerant in the receiver causing an increase in pressure
improved high side pressure control for heat pump sys
which is transmitted to the expansion valve connected to 70 tems which automatically reacts to a drop in head pres
the heat exchanger acting as an evaporator. During
sure to partially or completely ?ood the heat exchanger
periods when low temperature air is passing over the
acting as a. condenser. Such control provides proper
heat exchanger acting as a condenser the valve 42 modu
operating temperatures and pressures when operating on
lates so that the system substantially reaches an equi
the cooling cycle with low ambient air conditions sur
librium at which the high side pressure is satisfactory 75 rounding the heat exchanger acting as a condenser. Our
3,091,944:
5
6
system further eliminates on the heating cycle premature
temperature of the heat exchange medium passing through
icing of the heat exchanger acting as an evaporator and
said outdoor heat exchanger is below a predetermined
minimum.
eliminates unnecessary Wear on the compressor due to
excessive starting and stopping of the compressor on low
2. A reversible cycle refrigeration system comprising:
pressure cut-out.
an indoor heat exchanger, an outdoor heat exchanger,
Looking further at our new and novel head pressure
control for heat pump systems, it is obvious that we have
provided a control which is comparatively small in size,
conduit means for carrying liquid refrigerant connecting
said indoor heat exchanger to said outdoor heat ex
changer, a receiver connected to said conduit means, ex
pansion means operably associated with said heat ex
control of the ?ooding of the heat exchanger acting as a 10 changers, a compressor having a suction line and a
discharge line, reversing means connected to said discharge
condenser. Note that in both forms of the invention dur
and suction lines to reversibly connect said discharge and
ing conditions of high air temperaure, the hot gas bypass
suction line to said heat exchangers for effecting ?ow of
is positively closed, and that the compressor discharge
refrigerant through said system in either direction where
pressure acts directly on the held up liquid in the heat ex
changer acting as a condenser to force the liquid out of 15 by said system may be operated on a cooling cycle with
the outdoor coil functioning as a condenser or on a heat
the heat exchanger and allows it to operate at full capacity.
ing cycle with the indoor coil functioning as a condenser,
Although we have described in detail the preferred em
a hot gas bypass line connected to said discharge line, and
bodiments of our invention, we contemplate that many
automatic pressure responsive valve means connected to
changes may be made without departing from the scope
or spirit of our invention, and we desire to be limited only 20 said receiver, said conduit means, and said hot gas bypass
line to restrict the ?ow of refrigerant from said indoor
by the claims.
heat exchanger when the system is operating on the heat
We claim:
easy and inexpensive to manufacture, and gives positive
1. A reversible cycle refrigeration system comprising:
an indoor heat exchanger, an outdoor heat exchanger,
ing cycle and the temperature of the heat exchange
medium passing through said indoor heat exchanger is
conduit means for carrying liquid refrigerant connecting 25 below a predetermined minimum and to restrict the flow
of refrigerant from said outdoor heat exchanger when the
said indoor heat exchanger to said outdoor heat ex
system is operating in the cooling cycle and the tempera
changer, expansion means operably associated with said
ture of ‘the heat exchange medium passing through said
heat ‘exchangers, a compressor having a suction line and
outdoor heat exchanger is below a predetermined mini
a discharge line, reversing means connected to said dis
charge and suction lines to reversibly connect said dis 30 mum.
3. The structure of claim 2 wherein said automatic
charge and suction line to said heat exchangers for effect
pressure responsive valve means is a three way pressure
ing ?ow of refrigerant through said system in either direc
controlled valve with one port connected to said hot gas
bypass line, a second port connected to said conduit
cycle with the outdoor coil functioning as a condenser or
on a heating cycle with the outdoor coil functioning as a 35 means, and a third port in communication with said re
ceiver.
condenser or on a heating cycle with the indoor coil func
4. The structure of claim 3 wherein said automatic
tioning as a condenser, a hot gas bypass line connected to
pressure responsive valve means is :a pressure regulating
said discharge line, and automatic pressure responsive
valve in said hot gas bypass line and a back pressure valve
valve means connected to said conduit means and ‘said
hot gas bypass line to restrict the ?ow of refrigerant from 40 in said conduit means.
tion whereby said system may be operated on a cooling
said indoor heat exchanger when the system is operating
on the heating cycle and the temperature of the heat ex
change medium passing through said indoor heat ex
changer is below a predetermined minimum and to restrict
the flow of refrigerant from said outdoor heat exchanger 4
when the system is operating in the cooling cycle and the
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,874,550
2,954,681
2,976,696
Musson ______________ __ Feb. 24, 1959
McCormack ___________ __ Oct. 4, 1960
Rhea ________________ __ Mar. 28, 1961
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