Refrigeration – Refrigeration producer – Heat exchange between diverse function elements
Reexamination Certificate
2000-05-17
2002-06-18
Tanner, Harry B. (Department: 3744)
Refrigeration
Refrigeration producer
Heat exchange between diverse function elements
C062S200000, C062S505000
Reexamination Certificate
active
06405559
ABSTRACT:
This application is the national phase under 35 U.S.C. § 371 of PCT International Application No. PCT/JP98/04449 which has an International filing date of Oct. 2, 1998, which designated the United States of America.
TECHNICAL FIELD
The present invention relates to a refrigerating apparatus provided with an injection circuit.
BACKGROUND ART
Conventionally, as a refrigerating apparatus of this type, there has been one shown in FIG.
8
. This refrigerating apparatus has a main circuit
57
in which a compressor
51
, a condenser
52
, a supercooling heat exchanger
53
, a main expansion valve
54
, an evaporator
55
and an accumulator
56
are connected in series.
A branch pipe
60
that branches from the main circuit
57
between the condenser
52
and the supercooling heat exchanger
53
is connected to an inner pipe
53
A of the supercooling heat exchanger
53
.
This inner pipe
53
A extends from the downstream side to the upstream side inside an outer pipe
61
and is connected to an injection pipe
62
. The branch pipe
60
has a mechanical expansion valve
63
, and the degree of opening of this mechanical expansion valve
63
is changed by a signal from a thermosensitive tube
65
. attached to the injection pipe
62
.
The injection pipe
62
is connected to an intermediate-pressure portion
51
A of the compressor
51
. The injection pipe
62
has a solenoid controlled valve
66
. By opening and closing this solenoid controlled valve
66
, the injection of a gas refrigerant to the compressor
51
is turned on and off.
This refrigerating apparatus is improved in refrigerating efficiency by supercooling the refrigerant that is directed from the condenser
52
toward the main expansion valve
54
by a supercooling circuit constructed of the supercooling heat exchanger
53
, the branch pipe
60
and the mechanical expansion valve
63
. The refrigerating efficiency is further improved by injecting the branching refrigerant, which has absorbed heat in the supercooling heat exchanger
53
and comes from the branch pipe
60
, from the injection pipe
62
into the intermediate-pressure portion
51
A of the compressor
51
.
It is sometimes better for the improvement in efficiency to send the whole refrigerant to the evaporator
55
without making the main-stream refrigerant branch into the branch pipe
60
. In this case, the solenoid controlled valve
66
is closed so as to operate neither the supercooling circuit nor the injection circuit. It is to be noted that the mechanical expansion valve
63
cannot completely be closed due to its mechanism.
However, according to the aforementioned conventional refrigerating apparatus, noises occur due to the opening and closing of the solenoid controlled valve
66
provided for turning on and off the injection circuit, and this leads to the particular problem that noises are caused by the chattering at the time of change in pressure.
Furthermore, the provision of the solenoid controlled valve
66
only for turning on and off the injection circuit disadvantageously causes cost increase.
Next,
FIG. 10
shows the refrigerant circuit of another conventional refrigerating apparatus. This refrigerant circuit is provided with a main refrigerant circuit
210
in which a compressor
201
, a four-way control valve
202
, an outdoor heat exchanger
203
, a first expansion valve
205
, a gas-liquid separator
206
, a second expansion valve
207
and an indoor heat exchanger
208
are connected in series. This refrigerant circuit is further provided with a bypass circuit
211
for connecting the ceiling of the gas-liquid separator
206
to an intermediate-pressure portion
201
a
of the compressor
201
. This bypass circuit
211
has a solenoid controlled valve
212
. In this prior art example, the four-way control valve
202
makes a communication path indicated by the dashed lines during heating to execute a heating operation using the indoor heat exchanger
208
as a condenser. If the solenoid controlled valve
212
is opened during this heating, then a gas refrigerant from the gas-liquid separator
206
is made to pass through the bypass circuit
211
and injected into the intermediate-pressure portion
201
a
of the compressor
201
. As described above, it is sometimes the case where the amount of refrigerant flowing through the indoor heat exchanger
208
that is operating as a condenser is increased by bypassing the first expansion valve
205
and the outdoor heat exchanger
203
and returning the gas refrigerant from the bypass circuit
211
to the compressor
201
, for the improvement in efficiency.
FIG. 9
shows the above heating operation expressed by Mollier chart. As expressed by this Mollier chart, a flow rate Gc in the indoor heat exchanger
208
that serves as a condenser is the sum (Ge+Gi) of a flow rate Ge in the outdoor heat exchanger
203
that serves as an evaporator and a flow rate Gi through the bypass circuit
211
. If the whole gas is injected from the gas-liquid separator
206
into the compressor
201
, then the flow rate Gi of gas injection becomes (Gc×X). In this case, X represents the dryness (0.2 to 0.3, for example) of the refrigerant at the exit of the expansion valve
207
. Therefore, the flow rate Gc in the indoor heat exchanger
208
becomes Gc=Ge/(1−X).
If frost is formed on the outdoor heat exchanger
203
in this heating operation, then a reverse-cycle defrosting operation is executed. That is, the four-way control valve
202
is switched over to make the communication path indicated by the solid lines, by which the outdoor heat exchanger
203
is operated as a condenser to melt the frost. Then, by opening the solenoid controlled valve
212
also in this reverse-cycle defrosting operation, it is enabled to return the gas refrigerant from the bypass circuit
211
to the compressor
201
, increase the amount of refrigerant that is circulating from the compressor
201
to the outdoor heat exchanger
203
and rapidly melt the frost on the outdoor heat exchanger
203
.
However, during this reverse-cycle defrosting operation, as shown in
FIG. 11
, the dryness at the exit of the expansion valve
205
is small (for example, X=0.1 or smaller), when the gas component of the refrigerant is little. For this reason, the circulating refrigerant has increased less in amount even if the gas injection is executed during the defrosting operation, and this has resulted in little effect on reducing the defrosting time.
DISCLOSURE OF THE INVENTION
Accordingly, the first object of the present invention is to provide a low-noise low-cost refrigerating apparatus capable of controlling the supercooling circuit and the injection circuit. The second object of the present invention is to provide a refrigerating apparatus capable of reducing the defrosting time.
In order to achieve the above objects, the present invention provides a refrigerating apparatus that includes a compressor, a condenser, a main expansion mechanism, an evaporator and a supercooling circuit having a supercooling heat exchanger provided between the condenser and the main expansion mechanism and includes an injection circuit for injecting a gas refrigerant from the supercooling heat exchanger into an intermediate-pressure portion of the compressor, the apparatus comprising:
a motorized expansion valve provided in a supercooling pipe that diverges from a main flow on the upstream side of the supercooling heat exchanger and reaches the supercooling heat exchanger.
In this refrigerating apparatus, the injecting operation of the injection circuit can be turned off by completely closing the motorized expansion valve. The degree of supercooling of the supercooling circuit and the amount of injection of the injection circuit can be set to the desired values by controlling the degree of opening of the motorized expansion valve to the desired degree of opening.
That is, according to this refrigerating apparatus, the motorized expansion valve plays the role of the prior art solenoid controlled valve and the role of the prior art mechanical expansion v
Daikin Industries Ltd.
Tanner Harry B.
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