Note: Descriptions are shown in the official language in which they were submitted.
Il . 11~i9~5~ ~
AIRCONDITIONER
BACKGROUND OF THE INVENTION
This invention relates to improvements in an
airconditioner utilizing a vapor compressing and refrigerating
cycle, and particularly to such an airconditioner increased
in airconditioning capability during the drop in outdoor
temperature to efficiently cool and warm an associated room
or rooms in the whole year.
Heretofore there have been widely employed
airconditioners having the vapor compressing and refrigerating
cycle. Because of the atmosphere used as a heat source,
those airconditioners have been characterized in that the
capability of warming an associated room or rooms decreases
upon a reduction in outdoor temperature for example, in the
winter, in cold districts, in the morning or in the evening.
Particularly they have encountered the problem that, when
the outdoor air falls to a few temperature in Centigrade
above the freezing of water point, a frost is caused on the
surface of an outdoor heat exchanger resulting in a problem
that the heat exchange capability thereof is extremely
d!eteriorated .
There have been alreadily proposed some approaches
to that problem occurring in the room warming mode of
operation utilizing the atmosphere as a heat source. One of
the approaches has been to provide an indoor or an outdoor
heat exchanger with an electric heater serving as an auxiliary
heat source. For the indoor heat exchanger with the electric
heater, an indoor air blower is used to directly take out
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. 11~i9653
warm air while for the outdoor heat exchanger with the
electric heater, a refrigerant involved is heated by the
electric heater for the purpose of transporting heat to the
indoors. However the use of such an electric heater as the
auxiliary heat source has been disadvantageous in that the
cost of operation is expensive as compared with other heat
sources and a limitation exists in view of the installation
of an electric source involved.
Also it has been previously known to provide the
outdoor heat exchanger with a water heater. This measure
has be required to use a boiler resulting in the high cost
of equipment and also in a large-sized apparatus which is
inevitably attended with a large area occupied thereby. On
the other hand, the frost on the outdoor heat exchange has
been able to be removed in the room cooling mode of operation
performed for a short time interval. This measure, however,
has been disadvantageous in that the defrosting increases a
heat loss and the room warming mode of operation is
temporarily suspended.
In addition, there has been proposed a measure ~f
replenishing a lack of a room warming capability. According
to the measure, a combustion device has been incorporated
into an indoor exchanger to heat an associated heat exchanger
with the resulting combustion gas thereby to supply warm air
to the interior of the particular room or rooms for room
warming purposes, while the combustion gas is externally
exhausted after having heated the heat exchanger and the
room or rooms is or are cooled by a room cooling device
separately di'sposed. Thus the presence of the indoor
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11~i9653
combustion device has been disadvantageous in that it is
required to dispose pipings for sucking burning air and
exhausting the exhaust combustion gas which results in many
limitations as to the installation.
On the contrary, there has been also another
measure of providing the outdoor heat exchanger with a
combustion device as a heat source enabled in the room
warming mode of the operation. A combustion gas from the
combustion device has supplied thermal energy required for
the particular refrigeratnt to be evaporated thereby to
prevent a reduction in room warming capability upon a decrease
in outdooe temperature. With a high temperature combustion
gas used as the heat source, it is to be understood that a
contrivance is required not only to efficiently use the heat
for evaporating the refrigerant but also to solve a problem
that a heating efficiency is not high. This is because even
though the outdoor heat exchanger would be partly heated by
the combustion device, the resulting heat is partly dissipated
through a piping to the indoors.
Accordingly it is an object of the present invention
to provide a new and improved airconditioner including a
refrigeration circuit in which a liquid and a vapor phase of
a refrigerant involved are distributed in well balaned state
in any of modes of operation to be highly economically
operated in the whole year.
SUMMARY OF THE INVENTION
The present invention provides an airconditioner
selectively operative in the room cooling mode, the first
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room warming mode using the outdoor air as a heat source,
and the second room warming mode using a forced heat
generation source as a heat source, comprising compressor
means for compressing a refrigerant; an indoor heat exchanger
disposed in heat exchange relationship with the indoor air
to be operated as an evaporator in the room cooling mode of
operation and as a condenser in the first and second room
warming mode of operation; an outdoor heat exchanger disposed
in heat exchange relationship with the outdoor air to be
operated as a condenser in the room cooling mode of operation
and as an evaporator in the first room warming mode of
operation, the outdoor heat exchanger reserving therein the
refrigerant in its liquid phase in the second room warming
mode of operation; a separate heat exchanger for heating the .
refrigerant in the second room warming mode of operation,
the separate heat exchanger reserving therein the refrigerant
in its liquid phase in both the room cooling mode and the
first room warming mode of operation; forced heat generation
means for imparting heat to the separate heat exchanger in
the second room warming mode of operation; piping means for
reserving the refrigerant in its liquid phase in both the
room cooling mode and the first room warming mode of
operation, the piping means having an internal volume added
to that of the separate heat exchanger to be substantially
eqaul to an internal volume of the outdoor heat exchanger;
the piping means being connected in series to the separate
heat exchanger at least in the second room warming mode of
operation; first valve means connected between the piping
means and the.outdoor heat exchanger to be open in both the
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room cooling mode and the first room warming mode of operation
and closed in the second room warming mode of operation;
first pressure reducing mechanism connected in series to the
first valve means to reduce a pressure of the refrigerant
flowing therethrough in the first room warming mode of
operation; first bypass means for bypassing the refrigerant
tending to flow into the first pressure reducing mechanism
in the room cooling mode of operation; second valve means
connected in parallel to the outdoor heat exchanger to be
open in the second room warming mode of operation and closed
in the remaining modes of operation; second pressure reducing
mechanism connected ~etween the indoor heat exchanger and
the piping means to reduce a pressure of the refrigerant
flowing therethrough in the room cooling mode of operation;
second bypass means for bypassing the refrigerant tending to
flow into the second pressure reducing mechanism in the
first and second room warming modes of operation; flow rate-
of-refrigerant adjusting means connected to the compressor
means to adjust a flow xate of the refrigerant flowing into
the separate heat exchanger in the second room warming mode
of operation; and control means for selectively controlling
the first and second valve means and the flow rate-of-
refrigerant adj-lsting means to selectively put them in their
operating positions as determined by the room cooling mode
and the first and second room warming mode of operation
respectively.
In order to selectively operate the airconditioner
in the first and second room warming modes, the control
means may be~connected to a temperature sensor means for
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S3
sensing an outdoor temperature and responsive to a sensed
outdoor temperature to select either one of the first and
second room warming modes of operation.
In a preferred embodiment of the present invention,
the aircondikioner may comprise a refrigerant compressor; a
four-way valve; an outdoor heat exchanger disposed in heat
exchange relationship with the outdoor air to be operated as
a condenser in the room cooling mode of operation and as an
evaporator in the first and second room warming modes of
operation the outdoor heat exchanger reserving the refrigerant
in its liquid phase in the second room warming mode of
operation; a parallel combination of a first check valve
permitting a refrigerant to flow therethrough in the room
cooling mode of operation, and a first pressure reducing
mechanism for reducing a pressure of the refrigerant flowing
therethrough in the first room warming mode of operation; a
first electromagnetic valve open in both the room cooling
mode and the first room warming mode of operation and closed
in the second room warming mode of operation; a piping for
reserving the refrigerant in its liquid phase in both the
room cooling mode and the first room warming mode of
operation; a separate heat exchanger heated by a burner to
heat the refrigerant, the separate heat exchanger reserving
the refrigerant in its liquid phase in both the room cooling
mode and the first room warming mode of operation, a parallel
combination of a second check valve permitting the refrigerant
to flow therethrough in the first and second room warming
modes of operation, and a second pressure reproducing
mechanism for reducing a pressure of the refrigerant in the
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room cooling mode of operation; and an indoor heat exchanger
disposed in heat exchanger relationship with the indoor air
to be operated as an evaporator in the room cooling mode of
operation and as a condenser in the first room warming mode
of operation; all the abovementioned components being
connected in series to one another in the named order and
the indoor refrigerant being connected to the four way valve
to form a refrigeration circuit in each of the room cooling
mode and the first room warming mode of operation with an
internal valume of the piping substantially equal to a
difference in internal volume between the outdoor heat
exchanger and the separate heat exchanger. The airconditioner
further comprises a second electromagnetic valve connected
in parallel to the outdoor heat exchanger between the piping
and the four-way valve to be open in the second room warming
mode of operation and closed in the remaining modes of
operation which valve forms a refrigerant circuit in the
second room warming mode of operation with the piping, the
indoor heat exchanger and the components disposed there-
between, and a series combination of a third electromagnetic
valve and a throttle mechanism conne~ted between a delivery
and a suction side of the compressor, the third electro-
magnetic valve being open in the second room warming mode of
operation.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more readily
apparent from the following detailed description taken in .
conjunction with the accompanying drawings in which:
1. t ~ 3
Figure 1 is a block diagram of a refrigerant
circuit running through one embodiment according to the
airconditioner of the present invention;
Figure 2 is a graph illustrating the relationship
between an entalpy of a refrigerant and a pressure thereof
useful in explaining the operation of the arrangement shown
in Figure l;
Figure 3 is a diagram similar to Figure 1 but
illustrating a modification of the present invention; and
Figure 4 is a diagram similar to Figure 1 but
illustrating another modification of the present invention.
Throughout the Figures like reference numerals
designate the identical or corresponding components.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to Figure 1 of the drawings, there
is illustrated a refrigeration circuit running through one
embodiment according to the airconditioner of the present
invention selectively operated in the room cooling mode, a
first room warming mode using the outdoor air as a heat
source and the second room warming mode using a burner as
the heat source. The arrangement illustrated comprises an
electrically driven refrigerant compressor 10 with an
accumulator lOa connected via a four-way reverse valve 12 to
a refrigeration circuit traced from an indoor heat exchanger
14, through a parallel combination of a check valve 16 and a
pressure reducing mechanism 18, a separate heat exchanger 20
and thence to a refrigeration piping 22. Then the
refrigeration piping 22 is connected to an electromagnetic
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valve 24 subsequently connected to a parallel combination of
a check valve 26 and a pressure reducing menanism 28 which
is, in turn, connected to an outdoor heat exchanger 30
subsequently, connected to the four-way reverse valve 12 to
complete a closed loop refrigeration circuit as shown at
solid line in Figure 1. Further an electromagnetic valve 32
is connected to a series combination of the components 24,
26-28 and 30 to form a branch for the refrigeration circuit
as shown also at solid line in Figure 1.
The compressor 10 is provided with a series
combination of an electromagnetic valve 34 and a throttle
mechanism 36 connected across a delivery and a suction side
thereof through the accumulator lOa for purposes as will be
apparent later. The four-way reverse valve 12 is connected
across the delivery and suction dides of the compressor 10
and operative to flow the refrigeration circuit with the
compressed refrigerant from the compressor 10 in the direction
of the arrow A shown in Figure 1 in the room cooling mode of
operation and in the direction of the arrow B also shown in
Figure 1 in the first and second room warming modes of
operation.
The indoor heat exchanger 14 is disposed in heat
exchanger relationship with the indoor air while the outdoor
heat exchanger 30 is disposed in heat exchanger relationship
with the outdoor air. The separate heat exchanger 20 is
operatively coupled to forced heat generation means such as
a burner 38. The burner 38 is supplied with a fuel-air
mixture preliminarily prepared by mixing air from an air
feed tube 40,with a fuel from a fuel feed tube 42 in a
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ll~ 3
proper proportion in order to prevent soot from being
generated in the combustion process. In the second room
warming mode of operation the burner 38 burns the fuel-air
mixture to supply combustion heat to the separate heat
exchanger 20. That is, this heat exchanger 20 exchanges
heat between the refrigerant flowing therethrough and the
resulting combustion gas.
- The arrangement comprises further a control unit
46 and a temperature sensor 48 operatively coupled to the
control unit to sense an outdoor temperature.
The check valve 16 is connected in the refrigeration
circuit so that the refrigerant is permitted to flow pass
therethrough from the indoor heat exchanger 14 to the separate
heat exchanger 20, that is, in the first and second warm
J modes of operation while the check valve 26 is arranged to
permit the refrigerant to flow therethrough from the outdoor '
heat exchanger 30 to the electromagnetic valve 24.
The operation of the arrangement shown in Figure l
will now be described. In the room cooling mode of operation
the control unit 46 is operated to close the electromagnetic
valves 32 and 34 and open the electromagnetic valve 24.
Thus the compressed refrigerant from the compressor lO flows
through the refrigeration circuit traced from the compressor
lO through the four-way valve 12, the outdoor heat exchanger
30, the check valve 26, the now open electromagnetic valve
24, the piping 22, the heat exchanger 20, the pressure
reducing mechanism 18, the indoor heat exchanger l~, the
four-way valve 12 and thence to the compressor lO.
I ~
Under these circumstances the indoor heat exchanger
14 is operated as an evaporator while the outdoor heat
exchanger 30 is operated as a condenser with the result that
the heat exchanger 20 and the piping 22 located upstream of
the pressure reducing mechanism 18 with respect to the
stream of the refrigerant are fully filled with the
refrigerant in its liquid phase.~ Also the pressure reducing
mechanism 28 is operated to reduce a pressure of the
refrigerant therethrough.
In the first room warming mode of operation using
the outdoor air as the heat source, the control unit 40 is
operated to close the electromagnetic valves 34 and 32 and
open the electromagnetic valve 24. Thus the compressed
referigerant flows through a refrigeration circuit traced
from th compressor 10 through the four-way valve 12, the
indoor heat exchanger 14, the check valve 16, the heat
exchanger 20, the piping 22, the now open electromagnetic
valve 24, the pressure reducing mechanism 28, the outdoor
heat exchanger 30, the four-way valve 12 and thence to the
compressor 10. At that time the heat exchangers 14 and 30
serve as a condensor and an evaporator respectively. Thus
the piping 22 and the heat exchanger 20 located upstream of
the pressure reducing mechanism 28 with respect to the
stream of the refrigerant are substantially fully filled
with the refrigerant in its liquid phase. The pressure
reducing mechanism 18 is operated to reduce a pressure of
the refrigerant flowing therethrGugh.
Also in the second room warming mode of operation
using the co,mbustion heat as a heat source, the electro-
1.1~ 3
magnetic valve 24 is closed while the electromagnetic valves32 and 34 are open. Therefore the compressed refrigerant
flows partly through a refrigeration circuit traced from the
compressor 10 through the four-way valve 12, the indoor heat
exchanger 14r the check valve 16, the heat exchanger 20, the
piping 22~ the now open electromagnetic valve 32, the four-
way valve 12 and thence to the compressor 10 on the one hand
and partly through a path traced from the compressor 10
through the now open electromagnetic valve 34 the throttle
mechanism 36 and thence to the compressor 10 on the other
hand. At that time the indoor heat exchanger 14 is operated
as a condenser while the heat exchanger 20 is operated as an
evaporator so that the refrigerant are evaporated under a
pxessure and at a temperature high as compared with the
first room warming mode of operation. Also the outdoor heat
exchanger 30 condenses the refrigerant and is filled with
the refrigerant in its liquid phase in the steady-state
operation. This is because the electromagnetic valve 24 is
in its closed position.
As described above, the control unit-40 selectively
control the closure and opening of the electromagnetic
values 24, 32 and 34 to selectively operate the arrangement
of Figure 1 in the room cooling mode and the first and
second room warming modes.~ To this end, the control unit 46
connected to the temperature sensor 48 has stored therein a
predetermined temperature set so that the outdoor heat
exchanger 30 can not provide a predetermined room warming
capability as a result of the outdoor temperature decreasing
to reduce a quantity of heat exchanged by the same. The
~ ;i3
control unit 46 compares that predetermined set temperature
with an outdoor temperature sensed by the temperature sensor
48 to determine if the sensed temperature is less than the
set temperature. When having determined so, the control
unit 46 controls the electromagnetic valves 24, 32 and 34 to
operate the arrangement of Figure 1 in the second room
warming mode. otherwise the control unit 46 controls those
electromagnetic valves to operate the arrangement in the
first room warming mode.
The fact that the outdoor heat exchanger 30 is
fully filled with the refrigerant in its liquid phase is
effective for permitting the heat exchanger 30 to dissipate
only an extremely small quantity of heat to the outdoor air.
This will now be described in conjunction with Figure 2
wherein there is illustrated a pressure p of the refrigerant
plotted in ordinate against an enthalpy i thereof in abscissa.
Figure 2 illustrates a heat cycle in the second room warming
mode of operation using an external heat source such as the
burner 38 on a Mollier chart for the refrigerant. The heat
cycle includes those portions designated by the reference
numerals 10, 14, 20j 22 and 30 and corresponding to the
compressor 10, the indoor heat exchanger 14, the heat
exchanger 20, the piping 22 and the outdoor heat exchanger
30 respectively. Also Figure 2 shows-a pair of isothermal
lines at dotted-and-dashed lines one of which is designated
by the reference numeral 100.
From Figure 2, it is seen that the pressure of the
refrigerant in the outdoor heat exchanger 30 is substantially
equal to that in the heat exchanger 20 but a temperature
~ 3
within the former heat exchanger is far less than that
within the latter and rather close to the outdoor temperature.
This means that the outdoor heat exchanger 30 scarecely
disF;ipates heat to the outdoor air.
Further heat from the heat exchanger 20 is
transmitted to the outdoor heat exchanger 30 only through a
refrigerant piping connecting the two heat exchangers to
each other. In other words this transmission of heat is
conducted through the refrigerant in its liquid phase flowing
through that piping or the thick wall portion thereof
resulting in an extremely small quantity of transmitted
heat.
Accordingly, even though the outdoor heat exchanger
30 would be cooled with any invaded external wind, the
resulting dissipation of heat is very minute. Therefore it
is possible to efficiently transmit a quantity of heat
absorbed by the refrigerant in the heat exchanger 20 to the
indoor heat exchanger 14.
Also the piping 22 is shown in Figure 1 as being
coated with a thermally isolating material 22a. As the
thermally isolating material 22a is effective for suppressing
the heat exchange effected between the piping 22 and that
portion of the outdoor air surrounding the latter. Thus the
refrigerant remains in its vapor or gas phase (see Figùre
2).
As described above, the heat exchanger 20 and the
piping 22 are fully filled with the refrigerant in its
liquid phase in the first room warming mode of operation
while the out,door heat exchanger 30 is fully filled with the
~ 3
refrigerant in its liquid phase in the second room warming
mode thereof. Accordingly, in order to ensure the good
operation in either of the first and second room warming
modes, it is important that the piping 22 have its internal
valume as determined so that the internal volume of the
outdoor heat exchanger 30 is substantially equal to the sum
of the internal volume of the heat exchanger 20 and that of
the piping 22.
Since the heat exchanger 20 is operatively coupled
to the combustion gas higher in temperature than the outdoor
air as the auxiliary heat source, the same can be fairly
small-sized as compared with the outdoor heat exchanger 30
resulting in a decrease in internal volume thereof. Therefore
it will readily be understood that the purpose of the piping
22 is to substantially compensate for a difference in internal
volume between the heat exchanger 20 ~nd 30.
Because of the presence of the piping 22, the
outdoor heat-exchanger 30 serves as a liquid reservoir in
the second room warming mode of operation and the heat
exchanger 20 and the piping 22 serve as liquid reservoirs in
both the first room warming mode thereof using the outdoor
air as the heat source and the room cooling mode thereof.
Thus in any of room warming and cooling modes of operation
just described, the refrigeration circuit includes the
refrigerant having its liquid phase substantially identical
in disbribution to its vapor phase.
From this it is seen that, by preliminarily
designing the proper distribution of the refrigerant
concerning its liquid and vapor phases, it is possible
always to perform the satisfactory operation.
1~ 3~3
By rendering the inside diameter of the check
valve 16 and the electromagnetic valve 32 larger than that
of the check valve 26 and the electromagnetic valve 24, a
power required,for the compressor 10 to be driven can
effectively reduce in the second room warming mode of
operation. This is because the check valve 16 and the
electromagnetic valve 32 have flowing therethrough the
refrigerant in its vapor and liquid phases or in its vapor
phase in the second room warming mode of operation so that
the use of the inside diameter as high as possible decreases
pressure loss.
Since the refrigeration circuit put in the second
room warming mode of operation decreases in pressure loss
and utilizes combustion heat at an elevated temperature as
the heat source as described above, the refrigerant can be
high in evaporating pressure within the heat exchanger 20
and the compressor 10 can have an extremely small compression
ratio. Thus,a compression work is small as compared with
the room cooling mode or the first room warming mode of
operation. However an increase in evaporating pressure
causes a decrease in specific volume of the refrigerant
sucked by the compressor 10. Therefore the refrigerant
increases in mass flow rate and therefore in quantity
recirculating through the refrigeration circuit~ This
increase in recirculating quantity causes an increase in
pressure loss through the refrigeration circuit. As a
result, the compression work is not so decreased which will
be evident from the following relationship between the
capability of, warming the room and the recirculating quantity
expressed by
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R = gG~qVN/v (1)
where R designates the room warming capability in Kcal/hr, q
the room warming effect in Kcal/Kg, V a cylinder volume of
the compressor in m3, v a specific volume in m3/kg of
the refrigerant sucked by the compressor/ N the number of
rotation of the compressor per minute, and G designate the
recirculating quantity in kg/hr of the refrigerant. Assuming
that a constant load is imposed on the room warming and R,
q, N and V are constant, a rise of the evaporating pressure
causes a aecrease in specific volume until the refrigerant
has its recirculating quantity in excess of a proper value
relative to the room warming capability R.
It is particularly noted that, as the compressor
is used in common to the room cooling mode and the first
room warming mode of operation, the refrigerant recirculates
in extremely excessive quantity through the refrigerant
circuit in the second room warming mode of operation. In
order to ajust this exccessively recirculating quantity
under a high evaporating pressure, the present invention
includes a shunt circuit formed of the electromagnetic valve
34 and the throttle mechanism 36 serving as flow rate-of-
refrigerant adjusting means. In the second room warming
mode of operation, the electromagnetic valve 34 is open by
the control unti 46 to permit one portion of the refrigerant
delivered from the delivery side of the compressor 10 to be
shunted to the suction side thereof. Then the throttle
mechanism 36 controls a quantity of the shunted refrigerant
so that the heat exchanger 30 has flowing through a
recirculating quantity of the refrigerant required for a
~ 53
-`-' I' ' ' .
¦ predetermined room warming capability to be exhibited. This
¦ measure permits a pressure loss on the refrigerant circuit
¦ to decrease to extremely reduce a power required for the
¦ compressor 10 in the second room warming mode of operation.
¦ While the present invention has been illustrated
¦ and described in conjunction with the heat exchanger 20
¦ located downstream of the parallel combination of~the check
¦ valve 16 and the pressure reducing mechanism 18 with respect
¦ to the stream of the refrigerant occurring in the first and
¦ second room warming mode of operation. It is to be understood
¦ that the same is not limited thereby or thereto and that the
¦ heat exchanger 20 may be located downstream of the electro-
¦ magnetic valve 32 as with respect to the stream of refrigerant
¦ occurring in the second room warming mode of operation.
¦ This is shown in Figure 3 wherein there is illustrated a
¦ modification of the present invention. The arrangement
¦ illustrated is different from that shown in Figure 1 only in
¦ that in Figure 3 the heat exchanger 20 is directly connected
¦ in series to the electromagnetic valve 32 on that side
¦ thereof nearer to the four-way valve.
¦ In the arrangement of Figure 1 -the refrigerant
¦ flowing through the refrigerant circuit in the second room
¦ warming mode of operation is adjusted to the optimum
¦ recirculating quantity by the electromagnetic valve 34 and
¦ the throttle mechanism 36 for shunting one portion of the
¦ refrigerant from the delivery side of the compressor 10 to
¦ the suction side thereof. However it is to be understood
¦ that present invention is not limited to such an adjustment
¦ of the flow ~ate of the refrigerant and that it is possible
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llti'~j53
to control the flow rate of the refrigerant by adjusting the
number of rotation in unit time of the compressor 10 as will
be seen from the expression (1). For example, this measure
may use a frequency converter for controlling a frequency of
an electric power applied to an electric motor for the
compressor 10.
Figure 4 shows another modification of the present
invention wherein a frequency converter 50 is disposed
between the control unit 40 and the compressor 10 with the
omission of the third electromagnetic valve 34 and the
throttle mechanism 36.
In other respects the arrangement illustrated is
identical to that shown in Figure 1.
In the arrangement of Figure 4 the frequency
converter 48 is responsive to a control signal from the
control unit 46 to control a frequency of an associated
electric source. The compressor 10 operated in the second
room warming mode is required to have its number of rotation
in unit time less than that for in each of the room cooling
mode and the room warming mode. Thus in the second room
warming mode of operation, the source frequency from the
frequency converter decreases in proportion to the number of
rotation in unit time required for the compressor 10 and
supplies the frequency thus decreased to the electric motor
for the compressor 10. This measure permits the flow rate
of the refrigerant recirculating through the heat exchanger
20 to be adjusted to a proper magnitude resulting in a
reduction in electric power required for the compressor to
be driven.
i~ 36S3
The present invention has several advantages. For
example, a heat loss due to the heat dessipation to the
outdoor air can be suppressed in the second room warming
mode of operation and also the refrigerant has its liquid
and vapor phases distributed in the well balanced state
within the refrigerant circuit in any of the modes of
operation. Accordingly the present air conditioner can be
highly economically operated in the whole year.
While the present invention has been illustrated
and described in conjunction with a few preferred embodiments
thereof it is to be understood that numerous changes and
modifications may be resorted to without departing from the
spirit and scope of the present invention. For example, the
compressor 10 may be replaced by a volume controlled
compressor including the so-called bypass passageway with a
control valve disposed in the main body thereof with the
omission of the electromagnetic valve 34 and the throttle
mechanism 36.
