JP5068340B2 - Freezer refrigerator - Google Patents

Description

  The present invention relates to a refrigerator-freezer that performs hot gas defrosting.

  The refrigerant circuit in the refrigerator / freezer is composed of a compressor, a condenser, a capillary tube, and an evaporator in this order, and cools the air in the storage by the evaporator. The air cooled in the evaporator is sent out to a storage (a refrigeration room, a freezing room, a vegetable room, or the like) by an internal fan, and forms a circulation air path that returns from the storage to the evaporator again. Moisture that enters the storage as the door of the storage opens or closes or moisture contained in the air in the storage due to the moisture of the food adheres to the surface of the low-temperature evaporator and forms frost. When the cooling operation is carried out for about one day, the evaporator is covered with frost, the ventilation resistance of the evaporator is increased and the air volume is reduced, and the thermal resistance between the refrigerant and the air is increased and the refrigeration capacity is reduced. Therefore, it is necessary to defrost the evaporator once a day in order to suppress a decrease in the refrigerating capacity.

  In a conventional refrigerator, a heater type defrosting operation is common. However, in the form in which the evaporator is arranged near the freezer compartment, the ratio of the heat of the heater leaking into the storage during the defrosting operation is high. Not only does the internal temperature rise and food quality decreases, but power consumption during cooling operation increases. Here, a bypass pipe connecting between the compressor and the condenser, and between the capillary tube and the evaporator, and a hot gas defrosting type removal in which the refrigerant flow is switched to the bypass pipe by a three-way valve during the defrosting operation. There is a refrigerator-freezer that performs a frost operation (see, for example, Patent Document 1). In this hot gas defrosting type defrosting operation, by supplying gas refrigerant compressed to a high temperature and high pressure with a compressor to the evaporator, the frost is melted from the inside, so compared to the heater type defrosting operation, An increase in the internal temperature can be suppressed. Therefore, food quality can be kept good and power consumption can be reduced.

Japanese Patent Laying-Open No. 2005-249254 (page 4, FIG. 1)

  However, the refrigerator-freezer described in Patent Document 1 uses a three-way valve for switching between the cooling operation and the defrosting operation. During the cooling operation, the three-way valve causes the refrigerant flow path to be a discharge port of the compressor. Therefore, the refrigerant flow path from the discharge port of the compressor to the upstream side of the bypass pipe is closed. However, it is difficult to completely close the refrigerant flow path by the three-way valve, and the high-temperature and high-pressure gas refrigerant compressed by the compressor leaks directly from the slight gap into the bypass pipe. Therefore, since the leaked high-temperature and high-pressure gas refrigerant joins the low-temperature two-phase refrigerant between the evaporator and the capillary tube, there is a problem that the refrigerating capacity is lowered.

  The present invention has been made in order to solve the above-described problems, and it is an object of the present invention to suppress a decrease in refrigeration capacity due to a leakage refrigerant from a three-way valve and a refrigerant in a main circuit during a cooling operation. And

The refrigerator-freezer according to the present invention includes at least a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor and dissipates heat, and decompresses and expands the refrigerant condensed by the condenser. A main circuit in which a capillary, a three-way valve that switches a refrigerant flow path, the refrigerant flowing out of the capillary flows, and an evaporator that absorbs heat by evaporating the refrigerant flowing out of the three-way valve are sequentially connected by a refrigerant pipe; , a bypass pipe for connecting the refrigerant flow path and the three-way valve between the condenser and the compressor, and, and a bypass circuit constituted by the installed expansion device in the bypass pipe, the expansion When the refrigerant pressure between the expansion device and the three-way valve is P1 ′ and the refrigerant pressure between the capillary and the three-way valve is P2 ′, the capacity coefficient of the device is P2 ′ / P1 ′ < 0 .5 .

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the refrigerating capacity by the leakage refrigerant | coolant from a three-way valve and the refrigerant | coolant of a main circuit can be suppressed at the time of cooling operation.

It is a block diagram of the refrigerant circuit of the refrigerator-freezer which concerns on Embodiment 1 of this invention. It is a part of rear view of the refrigerator-freezer which concerns on Embodiment 1 of this invention. It is the figure which looked at the cooling room (storage room) 17 of the refrigerator-freezer which concerns on Embodiment 1 of this invention from the door front side. It is a ph diagram at the time of cooling operation in the refrigerator-freezer according to Embodiment 1 of the present invention. It is a ph diagram at the time of defrosting operation in the refrigerator-freezer according to Embodiment 1 of the present invention. It is a block diagram of the freezing circuit of the refrigerator-freezer which concerns on Embodiment 2 of this invention. It is a part of rear view of the refrigerator-freezer which concerns on Embodiment 2 of this invention. It is the figure which looked at the cooling room (storage room) 17 of the refrigerator-freezer which concerns on Embodiment 2 of this invention from the door front side. It is a ph diagram at the time of cooling operation in the refrigerator-freezer according to Embodiment 2 of the present invention. FIG. 10 is an enlarged view in the vicinity of point B and point C in the ph diagram shown in FIG. 9. It is a ph diagram at the time of defrosting operation in the refrigerator-freezer according to Embodiment 2 of the present invention.

Embodiment 1 FIG.
(Configuration of refrigeration circuit)
1 is a configuration diagram of a refrigerant circuit of a refrigerator-freezer according to Embodiment 1 of the present invention.
As shown in FIG. 1, a compressor 1 that compresses refrigerant, a condenser 2 that exchanges heat by condensing gas refrigerant compressed by the compressor 1, and freezing due to moisture in the refrigerant that has passed through the condenser 2. A dryer 3 for preventing, a capillary 4 for expanding the refrigerant that has passed through the dryer 3, and an evaporator 5 for evaporating the refrigerant that has flowed out of the capillary 4 and passed through the three-way valve 6 are sequentially connected by a refrigerant pipe. Is configured. Among these, the refrigerant pipe connecting the evaporator 5 and the compressor 1 is constituted by the suction pipe 20. In addition, an evaporator fan 11 that blows the air cooled by the evaporator 5 into a storage (a refrigeration room, a freezing room, a vegetable room, or the like) is installed above the evaporator 5.

  Further, a bypass circuit is configured by the bypass pipe 7 connecting the three-way valve 6, the refrigerant pipe connecting the compressor 1 and the condenser 2, and the capillary 8 installed in the bypass pipe 7. .

  The capillary 4 has a capacity coefficient (Cv value) in consideration of a pressure drop caused by passing through the three-way valve 6 and can be attenuated to a predetermined pressure.

  The three-way valve 6 is, for example, a rotary electromagnetic valve, which can be used even under a low temperature condition such as in a refrigerator, and has a flow path diameter comparable to that of the capillary 4.

  The capillary 8 has a capacity coefficient (Cv value) of a refrigerant at 0 ° C. from the discharge pressure of the compressor 1 in a hot gas defrosting defrosting operation (hereinafter simply referred to as “hot gas defrosting operation”) described later. The capacity coefficient (Cv value) is larger than that of the capillary 4.

  The capillary 8 corresponds to the “expansion device” in the present invention.

FIG. 2 is a part of a rear view of the refrigerator-freezer according to Embodiment 1 of the present invention, and FIG. 3 is a view of the cooling chamber (storage chamber) 17 of the refrigerator-freezer as viewed from the front side of the door.
As shown in FIG. 2, a machine room 12 is formed in the lower part of the back surface of the refrigerator-freezer according to the present embodiment. In the machine room 12, there are a compressor 1, a condenser 2, a dryer. 3. A machine room fan 13 for blowing air to the compressor 1 and a drain pan 14 are accommodated.

  Further, as shown in FIG. 3, the evaporator 5 is installed in the center of the cooling chamber 17, and the evaporator fan 11 that blows the cooled air into the cooling chamber 17 is installed on the upper portion of the evaporator 5. A tray 19 is installed in the lower part of the chamber 17.

Next, details of the refrigerant circuit path of the refrigerator-freezer according to the present embodiment will be described with reference to FIGS. 2 and 3.
First, the main circuit in the refrigerant circuit will be described. In the machine room 12, the refrigerant discharged from the compressor 1 flows into the condenser 2. The refrigerant that has flowed out of the condenser 2 circulates through a pipe disposed inside the steel plate 15 of the refrigerator-freezer main body that functions as a natural heat dissipation condenser outside the machine room 12, returns to the machine room 12 again, and the dryer. Into 3 The refrigerant that has flowed out of the dryer 3 flows again through the capillary 4 disposed inside the heat insulating wall 16 of the refrigerator-freezer main body outside the machine room 12, and this capillary 4 is cooled from the hole 18 that is the inlet of the cooling chamber 17. Enter the room 17. The refrigerant flows through the capillary tube 4 that has entered the cooling chamber 17 and flows into the evaporator 5 through the three-way valve 6 installed in the cooling chamber 17. The refrigerant flowing out of the evaporator 5 flows through the suction pipe 20, and the suction pipe 20 goes out of the cooling chamber 17 through the hole 18 serving as the outlet of the cooling chamber 17. The refrigerant flows through the suction pipe 20 that has exited the cooling chamber 17 and flows into the compressor 1 in the machine chamber 12.

  As described above, by using a three-way valve 6 that can be used even under low temperature conditions such as in a refrigerator, and installing the three-way valve 6 in the cooling chamber 17, the sound generated when the three-way valve 6 is switched. Can be confined in the cooling chamber 17, and the quietness of the refrigerator-freezer can be realized.

  Next, a bypass circuit in the refrigerant circuit will be described. In the machine room 12, the refrigerant discharged from the compressor 1 flows through the bypass pipe 7, and the capillary tube 8 in the bypass pipe 7 disposed inside the heat insulating wall 16 of the refrigerator-freezer main body outside the machine room 12. Circulate. The capillary 8 enters the cooling chamber 17 from the hole 18 that is the inlet of the cooling chamber 17. The refrigerant flows through the capillary 8 as the bypass pipe 7 and reaches the three-way valve 6 installed in the cooling chamber 17. Here, the capillary 8 installed in the bypass pipe 7 is passed from the center in the thickness direction of the heat insulating wall 16 on the back surface of the refrigerator-freezer to the outer half, thereby suppressing wasteful heat dissipation.

(Cooling operation of freezer refrigerator)
FIG. 4 is a ph diagram during cooling operation in the refrigerator-freezer according to Embodiment 1 of the present invention. The refrigerant states at points A to F in FIG. 4 correspond to the refrigerant states at points A to F in FIG. The cooling operation of the refrigerator-freezer according to the present embodiment will be described with reference to FIGS. 4 and 1.

  The state of the refrigerant in the refrigeration cycle of the main circuit in the cooling operation transitions in the order of A → B → C → D → E. In the cooling operation, the flow path from the bypass circuit is closed in advance by the three-way valve 6. The high-temperature and high-pressure gas refrigerant (point A) compressed and discharged by the compressor 1 flows into the condenser 2. The gas refrigerant that has flowed into the condenser 2 undergoes heat exchange with the air in the machine chamber 12 to condense, become liquid refrigerant, and flow out of the condenser 2. At this time, the condenser 2 dissipates heat by condensing the gas refrigerant. The liquid refrigerant (point B) flowing out of the condenser 2 passes through the dryer 3 and flows into the capillary tube 4 and is expanded and decompressed by the capillary tube 4 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant (point C). This gas-liquid two-phase refrigerant passes through the three-way valve 6 (point D), flows into the evaporator 5, and exchanges heat (heat) with the air in the cooling chamber 17 sent by the rotation drive of the evaporator fan 11. Is absorbed and vaporized, and becomes a low-temperature and low-pressure gas refrigerant and flows out of the evaporator 5. The gas refrigerant (point E) flowing out from the evaporator 5 flows through the suction pipe 20, flows into the compressor 1, and is compressed again.

  Further, as described above, although the flow path from the bypass circuit is closed, the refrigerant from the bypass circuit leaks into the main circuit through a slight gap in the three-way valve 6. The state of the refrigerant with respect to the leaked refrigerant transitions in the order of A → F → D → E. The high-temperature and high-pressure gas refrigerant (point A) compressed and discharged by the compressor 1 flows through the bypass pipe 7, flows into the capillary tube 8 installed in the bypass pipe 7, and is expanded and depressurized by the capillary tube 8 (point F) Further, the refrigerant is expanded and depressurized in the three-way valve 6, and in this three-way valve 6, the refrigerant flows in from the capillary 4 in the main circuit (point D) and flows into the evaporator 5. The refrigerant that has flowed into the evaporator 5 flows out of the evaporator 5 as a low-temperature and low-pressure gas refrigerant as described above. The gas refrigerant (point E) flowing out from the evaporator 5 flows through the suction pipe 20, flows into the compressor 1, and is compressed again.

  Here, the refrigerant in the state of the point C in the main circuit increases the enthalpy from the state of the point C to the state of the point D due to the merge with the refrigerant leaking from the bypass circuit. As a result, the refrigerating capacity is reduced. The amount of increase in enthalpy is proportional to the leakage flow rate, and the leakage flow rate is calculated by the following equation (1).

In this equation (1), Q is the leakage flow rate [m ³ / h], P1 ′ is the refrigerant pressure [MPa] after passing through the capillary 8, and P2 ′ is the refrigerant pressure between the capillary 4 and the three-way valve 6 [ MPa], G is the specific gravity of the refrigerant after passing through the capillary 8, and Cv is a capacity coefficient when the flow path from the bypass circuit of the three-way valve 6 is closed. Here, since the refrigerant pressure P1 ′ is the refrigerant pressure downstream of the high-pressure bypass circuit and the refrigerant pressure P2 ′ is the pressure downstream of the low-pressure capillary 4, the relationship between the refrigerant pressure P1 ′ and the refrigerant pressure P2 ′ is The relationship of P2 ′ / P1 ′ <0.5 is satisfied, and the flow of the leaked refrigerant is a choke flow. In this case, the leak flow rate Q is a value that does not depend on the refrigerant pressure P2 ′ as shown in the equation (1). Become. The refrigerant in the bypass circuit decreases in pressure and temperature by passing through the capillary tube 8, so that the refrigerant pressure P 1 ′ and the specific gravity G of the refrigerant at this time are higher than the pressure and specific gravity of the refrigerant discharged from the compressor 1. In addition, since the rate of decrease in the refrigerant pressure is greater than the rate of decrease in specific gravity, the leakage flow rate Q from the bypass circuit to the main circuit via the three-way valve 6 in this case is not provided with the capillary tube 8. It becomes smaller than the leakage flow rate. As a result, the increase in enthalpy due to the leakage refrigerant from the bypass circuit joining the refrigerant flowing through the main circuit is also reduced, and the reduction in the refrigeration capacity of the refrigeration cycle is suppressed.

(Defrosting operation of a refrigerator)
FIG. 5 is a ph diagram during the defrosting operation in the refrigerator-freezer according to Embodiment 1 of the present invention. The refrigerant states at points A, E, and F in FIG. 5 correspond to refrigerant states at points A, E, and F in FIG. The hot gas defrosting operation of the refrigerator-freezer according to this embodiment will be described with reference to FIGS. 5 and 1.

  The state of the refrigerant in the refrigeration cycle in the hot gas defrosting operation transitions in the order of A → F → E. In the hot gas defrosting operation, the flow path from the capillary 4 is closed in advance by the three-way valve 6. The high-temperature and high-pressure gas refrigerant (point A) compressed and discharged by the compressor 1 flows through the bypass pipe 7, flows into the capillary tube 8 installed in the bypass pipe 7, and is expanded and depressurized by the capillary tube 8 ( Point F). Then, the refrigerant flowing out from the capillary tube 8 passes through the three-way valve 6 and flows into the evaporator 5. Here, the refrigerant flowing into the evaporator 5 maintains a high temperature, and the frost generated in the evaporator 5 is dissolved and removed by the high-temperature refrigerant. Thereafter, the refrigerant (point E) flowing out of the evaporator 5 flows into the compressor 1 and is compressed again. By the above hot gas defrosting operation, the temperature rise in the cooling chamber 17 can be suppressed, the quality of the food stored in the cooling chamber 17 can be maintained well, and the conventional heater type Power consumption can be reduced as compared with the defrosting operation.

(Effect of Embodiment 1)
By providing the capillary 8 in the bypass circuit as in the above configuration and operation, the leakage flow rate of the refrigerant from the bypass circuit to the main circuit during the cooling operation can be reduced. It is possible to suppress a decrease in the refrigerating capacity due to the merging, and to maintain good quality of food stored in the cooling chamber and reduce power consumption during the hot gas defrosting operation.

  In addition, by using a three-way valve 6 that can be used even under low temperature conditions such as in a refrigerator, and installing the three-way valve 6 in the cooling chamber 17, the sound generated when the three-way valve 6 is switched is cooled. 17 can be confined, and quietness of the refrigerator-freezer can be realized.

  Further, when the three-way valve 6 has a flow path diameter similar to that of the capillary tube 4 and the capillary tube 4 has a capacity coefficient (Cv value) considering the pressure drop due to passing through the three-way valve 6, the three-way valve 6 The capacity of the refrigerator can be increased by downsizing.

  Moreover, useless heat dissipation can be suppressed by letting the capillary tube 8 installed in the bypass pipe 7 pass through the range from the center in the thickness direction of the heat insulating wall 16 on the back of the refrigerator-freezer to the outer half.

  Further, by providing the three-way valve 6 between the capillary 4 on the low pressure side and the evaporator 5, it is possible to reduce the pressure resistance of the three-way valve 6, thereby achieving downsizing and cost reduction. be able to.

Embodiment 2. FIG.
(Configuration of refrigeration circuit)
FIG. 6 is a configuration diagram of a refrigeration circuit of a refrigerator-freezer according to Embodiment 2 of the present invention.
As shown in FIG. 6, the compressor 1 that compresses the refrigerant, the condenser 2 that exchanges heat and condenses the gas refrigerant compressed by the compressor 1, passes through the condenser 2, and further passes through the three-way valve 6. A dryer 3 for preventing freezing due to moisture in the refrigerant, a capillary 4 that expands the refrigerant that has passed through the dryer 3 and further passed through the three-way valve 9, and an evaporator 5 that evaporates the refrigerant flowing out of the capillary 4 Sequentially connected by refrigerant pipes constitute a main circuit. Among these, the refrigerant pipe connecting the evaporator 5 and the compressor 1 is constituted by the suction pipe 20. In addition, an evaporator fan 11 that blows the air cooled by the evaporator 5 into a storage (a refrigeration room, a freezing room, a vegetable room, or the like) is installed above the evaporator 5.

  Further, a bypass circuit 31 is constituted by a bypass pipe 23 that connects the three-way valve 22 and a refrigerant pipe that connects between the compressor 1 and the condenser 2. And the bypass circuit 32 is comprised by the bypass pipe 10 which connects the three way valve 9, the refrigerant | coolant piping which connects between the capillary 4 and the evaporator 5, and the capillary 21 installed in the bypass piping 10. FIG. .

  The three-way valve 22 and the three-way valve 9 have the same capacity coefficient (Cv value) when the three-way valve 6 is closed in the first embodiment.

  The capillary 21 has a capacity coefficient (Cv value) that can be attenuated from the discharge pressure of the compressor 1 to the saturated vapor pressure of the refrigerant at 0 ° C. in the hot gas defrosting operation described later. Cv value) is large.

  The capillary 21, the three-way valve 22, and the three-way valve 9 correspond to the “expansion device”, the “first three-way valve”, and the “second three-way valve” in the present invention, respectively. Further, the bypass pipe 23 and the bypass circuit 31 correspond to the “first bypass pipe” and the “first bypass circuit” in the present invention, respectively. The bypass pipe 10 and the bypass circuit 32 correspond to the “second bypass pipe” and the “second bypass circuit” in the present invention, respectively.

FIG. 7 is a part of a rear view of the refrigerator-freezer according to Embodiment 2 of the present invention, and FIG. 8 is a view of the cooling chamber (storage chamber) 17 of the refrigerator-freezer as viewed from the front side of the door.
As shown in FIG. 7, a machine room 12 is formed in the lower part of the back surface of the refrigerator-freezer according to the present embodiment. In the machine room 12, there are a compressor 1, a condenser 2, a dryer. 3, a three-way valve 9, a machine room fan 13 that blows air to the compressor 1, a drain pan 14, and a bypass pipe 23 are accommodated. The three-way valve 9 is disposed on the opposite side of the compressor 1 with respect to the machine room fan 13, and is disposed at a position where the machine room fan 13 blows air. Thereby, the air heated with the compressor 1 will be sprayed on the capillary tube 21, and heat dissipation can be suppressed.

  Further, as shown in FIG. 8, the evaporator 5 is installed in the center of the cooling chamber 17, and the evaporator fan 11 that blows the cooled air into the cooling chamber 17 is installed on the upper portion thereof, and cooling is performed. A tray 19 is installed in the lower part of the chamber 17.

Next, details of the route of the refrigerant circuit of the refrigerator-freezer according to the present embodiment will be described with reference to FIGS.
First, the main circuit in the refrigerant circuit will be described. In the machine room 12, the refrigerant discharged from the compressor 1 flows into the condenser 2. The refrigerant that has flowed out of the condenser 2 circulates in a pipe disposed inside the steel plate 15 of the refrigerator-freezer body that functions as a natural heat dissipation condenser outside the machine room 12, returns to the machine room 12, and returns to the three-way side. It flows into the dryer 3 through the valve 22. The refrigerant that has flowed out of the dryer 3 passes through the three-way valve 9 and again flows through the capillary tube 4 disposed inside the heat insulating wall 16 of the refrigerator-freezer main body outside the machine room 12. The capillary tube 4 is connected to the cooling chamber 17. It enters into the cooling chamber 17 through the hole 18 that is the inlet. The refrigerant flows through the capillary 4 that has entered the cooling chamber 17 and flows into the evaporator 5. The refrigerant flowing out of the evaporator 5 flows through the suction pipe 20, and the suction pipe 20 goes out of the cooling chamber 17 through the hole 18 serving as the outlet of the cooling chamber 17. The refrigerant flows through the suction pipe 20 that has exited the cooling chamber 17 and flows into the compressor 1 in the machine chamber 12.

  Next, the bypass circuits 31 and 32 in the refrigerant circuit will be described. In the bypass circuit 31, the refrigerant discharged from the compressor 1 in the machine room 12 flows through the bypass pipe 23 and reaches the three-way valve 22. In the bypass circuit 32, the refrigerant flowing out from the three-way valve 9 in the machine room 12 circulates through the capillary 21 in the bypass pipe 10 disposed inside the heat insulation wall 16 of the refrigerator-freezer body outside the machine room 12. The capillary 21 enters the cooling chamber 17 through the hole 18 that is the inlet of the cooling chamber 17. The refrigerant flows through the capillary tube 21 as the bypass pipe 10 and reaches the evaporator 5 installed in the cooling chamber 17. Here, the capillary tube 21 installed in the bypass pipe 10 is passed from the center in the thickness direction of the heat insulating wall 16 on the back surface of the refrigerator-freezer to the outer half, so that useless heat dissipation can be suppressed.

(Cooling operation of freezer refrigerator)
FIG. 9 is a ph diagram at the time of cooling operation in the refrigerator-freezer according to Embodiment 2 of the present invention, and FIG. 10 is the vicinity of point B and point C in the ph diagram shown in FIG. It is an enlarged view. The refrigerant states at points A to E in FIG. 9 correspond to the refrigerant states at points A to E in FIG. The cooling operation of the refrigerator-freezer according to the present embodiment will be described with reference to FIG. 9, FIG. 10, and FIG.

  The state of the refrigerant in the refrigeration cycle of the main circuit in the cooling operation transitions in the order of A → B → C → D → E. In the cooling operation, the flow path from the bypass circuit 31 is closed in advance by the three-way valve 22, and the flow path to the bypass circuit 32 is closed in advance by the three-way valve 9. The high-temperature and high-pressure gas refrigerant (point A) compressed and discharged by the compressor 1 flows into the condenser 2. The gas refrigerant that has flowed into the condenser 2 undergoes heat exchange with the air in the machine chamber 12 to condense, become liquid refrigerant, and flow out of the condenser 2. At this time, the condenser 2 dissipates heat by condensing the gas refrigerant. The liquid refrigerant flowing out of the condenser 2 (point B) passes through the three-way valve 22 (point C), passes through the dryer 3, and further passes through the three-way valve 9 and flows into the capillary tube 4. The refrigerant is expanded and depressurized by the capillary 4 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant (point D). This gas-liquid two-phase refrigerant flows into the evaporator 5, undergoes heat exchange (absorbs heat) with the air in the cooling chamber 17 sent by the rotation drive of the evaporator fan 11, vaporizes, and is cooled at low temperature and low pressure. Gas refrigerant flows out of the evaporator 5. The gas refrigerant (point E) flowing out from the evaporator 5 flows through the suction pipe 20, flows into the compressor 1, and is compressed again.

  Further, as described above, although the flow path from the bypass circuit 31 is closed, the refrigerant from the bypass circuit 31 leaks from the slight gap of the three-way valve 22 to the main circuit. The state of the refrigerant with respect to the leaked refrigerant changes in the order of A → C → D → E. The high-temperature and high-pressure gas refrigerant (point A) compressed and discharged by the compressor 1 flows through the bypass pipe 23 and joins with the refrigerant flowing from the condenser 2 in the main circuit at the three-way valve 22 (point C). , Flows into the dryer 3. Then, the refrigerant that has passed through the dryer 3 flows into the capillary tube 4 through the three-way valve 9, and is expanded and depressurized by the capillary tube 4 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant (point D). Flow into. The refrigerant that has flowed into the evaporator 5 flows out of the evaporator 5 as a low-temperature and low-pressure gas refrigerant as described above. The gas refrigerant (point E) flowing out from the evaporator 5 flows through the suction pipe 20, flows into the compressor 1, and is compressed again.

  Here, the refrigerant in the state of point B in the main circuit increases in enthalpy from the state of point B to the state of point C due to merging with the refrigerant leaking from the bypass circuit 31, so that there is no refrigerant leakage. As a result, the refrigerating capacity is reduced. The amount of increase in enthalpy is proportional to the leakage flow rate, and the leakage flow rate is calculated by the following equation (2).

In this equation (2), Q is the leakage flow rate [m ³ / h], P1 ′ is the discharge pressure from the compressor 1 (refrigerant pressure in the bypass pipe 23) [MPa], and P2 ′ is the condenser 2 and the three-way valve 22. Refrigerant pressure [MPa], G is the specific gravity of the refrigerant in the bypass pipe 23, Cv is the capacity coefficient when the flow path from the bypass circuit 31 of the three-way valve 22 is closed, and ΔP ′ is the refrigerant pressure P1 ′. This is the pressure difference (P1′−P2 ′) from the refrigerant pressure P2 ′. In the main circuit, pressure loss occurs when the refrigerant passes through the condenser 2, so that the refrigerant pressure P2 'is lower than the refrigerant pressure P1', but the amount of decrease is very small, and the refrigerant pressure P1 ' The pressure ratio with the refrigerant pressure P2 ′ is larger than 0.5. Here, in the refrigerant circuit shown in FIG. 1 of Patent Document 1, the refrigerant pressure P1 ′ is the refrigerant pressure discharged from the compressor, the refrigerant pressure P2 ′ is the refrigerant pressure in the bypass pipe, and the specific gravity G is the compressor. Assuming that the specific gravity of the refrigerant discharged from the refrigerant is, the leakage flow rate is calculated by the equation (1) in the first embodiment. At this time, when the specific gravity G, the capacity coefficient Cv of the three-way valve 22 (three-way valve 2 in Patent Document 1), and the refrigerant pressure P1 ′ are equal, √ {ΔP ′ in the equation (2) of the present embodiment. (P1 ′ + P2 ′)} (= √ (P1 ′ ² −P2 ′ ² ) is a value smaller than 0.87 · P1 ′ ² in the equation (1) in the case of Patent Document 1, and therefore, the present embodiment The leakage flow rate Q in the refrigerant is smaller than the leakage flow rate in Patent Document 1. As a result, the increase in enthalpy due to the leakage refrigerant from the bypass circuit 31 joining the refrigerant flowing through the main circuit is also reduced. Thus, a decrease in the refrigeration capacity of the refrigeration cycle is suppressed.

(Defrosting operation of a refrigerator)
FIG. 11 is a ph diagram during the defrosting operation in the refrigerator-freezer according to Embodiment 2 of the present invention. The refrigerant states at points A, D and E in FIG. 11 correspond to the refrigerant states at points A, D and E in FIG. The hot gas defrosting operation of the refrigerator-freezer according to the present embodiment will be described with reference to FIGS. 11 and 6.

  The state of the refrigerant in the refrigeration cycle in the hot gas defrosting operation transitions in the order of A → D → E. In the hot gas defrosting operation, the flow path from the condenser 2 is closed in advance by the three-way valve 22, and the flow path to the capillary 4 is closed in advance by the three-way valve 9. The high-temperature and high-pressure gas refrigerant (point A) compressed and discharged by the compressor 1 flows through the bypass pipe 23 and further passes through the three-way valve 22, the dryer 3 and the three-way valve 9, and flows into the capillary 21. It is expanded and depressurized by the capillary 21 (point D). Then, the refrigerant flowing out from the capillary 21 flows into the evaporator 5. Here, the refrigerant flowing into the evaporator 5 maintains a high temperature, and the frost generated in the evaporator 5 is dissolved and removed by the high-temperature refrigerant. Thereafter, the refrigerant (point E) flowing out of the evaporator 5 flows into the compressor 1 and is compressed again. By the above hot gas defrosting operation, the temperature rise in the cooling chamber 17 can be suppressed, the quality of the food stored in the cooling chamber 17 can be maintained well, and the conventional heater type Power consumption can be reduced as compared with the defrosting operation.

(Effect of Embodiment 2)
As described above, the cooling operation is provided by including the bypass circuit 31 including the three-way valve 22 and the bypass pipe 23 connecting the refrigerant pipe connecting the compressor 1 and the condenser 2. Since the leakage flow rate of the refrigerant from the bypass circuit 31 to the main circuit at the time can be reduced, it is possible to suppress a decrease in refrigeration capacity due to the merge of the leaked refrigerant to the main circuit, and at the time of hot gas defrosting operation In, the quality of the food stored in the cooling chamber can be maintained satisfactorily and the power consumption can be reduced.

  Moreover, useless heat dissipation can be suppressed by letting the capillary tube 21 installed in the bypass pipe 10 pass through the range from the center in the thickness direction of the heat insulating wall 16 on the back of the refrigerator-freezer to the outer half.

  And by arrange | positioning the three-way valve 9 on the opposite side to the machine room fan 13 with respect to the compressor 1, the heat heated by the compressor 1 is sprayed on the capillary tube 21, whereby heat radiation can be suppressed.

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Condenser, 3 Dryer, 4 Capillary, 5 Evaporator, 6 Three-way valve, 7 Bypass piping, 8 Capillary, 9 Three-way valve, 10 Bypass piping, 11 Evaporator fan, 12 Machine room, 13 Machine room fan , 14 Drain pan, 15 Steel plate, 16 Heat insulation wall, 17 Cooling chamber, 18 holes, 19 Tray, 20 Suction pipe, 21 Capillary tube, 22 Three-way valve, 23 Bypass piping, 31, 32 Bypass circuit.

Claims (9)

At least a compressor that compresses the refrigerant, a condenser that condenses the refrigerant compressed by the compressor and dissipates heat, a capillary that decompresses and expands the refrigerant condensed by the condenser, and a refrigerant flow path A main circuit in which a three-way valve into which refrigerant flowing out from the capillary flows and an evaporator that absorbs heat by evaporating the refrigerant flowing out from the three-way valve are sequentially connected by a refrigerant pipe;
At least a bypass pipe connecting the refrigerant flow path between the compressor and the condenser and the three-way valve, and a bypass circuit configured by an expansion device installed in the bypass pipe;
Equipped with a,
The capacity coefficient of the expansion device is P2 ′ / P1 when the refrigerant pressure between the expansion device and the three-way valve is P1 ′ and the refrigerant pressure between the capillary and the three-way valve is P2 ′. ' A refrigerator-freezer characterized by satisfying <0.5 . At least a compressor that compresses the refrigerant, a condenser that condenses the refrigerant compressed by the compressor and dissipates heat, a capillary that decompresses and expands the refrigerant condensed by the condenser, and a refrigerant flow path A main circuit in which a three-way valve into which refrigerant flowing out from the capillary flows and an evaporator that absorbs heat by evaporating the refrigerant flowing out from the three-way valve are sequentially connected by a refrigerant pipe;
At least a bypass pipe connecting the refrigerant flow path between the compressor and the condenser and the three-way valve, and a bypass circuit configured by an expansion device installed in the bypass pipe;
With
The three-way valve had a flow channel diameter substantially the same as the capillary flow channel diameter.
A refrigerator-freezer characterized by that. At least a compressor that compresses the refrigerant, a condenser that condenses the refrigerant compressed by the compressor and dissipates heat, a capillary that decompresses and expands the refrigerant condensed by the condenser, and a refrigerant flow path A main circuit in which a three-way valve into which refrigerant flowing out from the capillary flows and an evaporator that absorbs heat by evaporating the refrigerant flowing out from the three-way valve are sequentially connected by a refrigerant pipe;
At least a bypass pipe connecting the refrigerant flow path between the compressor and the condenser and the three-way valve, and a bypass circuit configured by an expansion device installed in the bypass pipe;
With
The expansion device is installed in the range of the outer half from the center in the thickness direction of the main body wall of the refrigerator-freezer.
A refrigerator-freezer characterized by that. The refrigerator-freezer according to claim 1, wherein the three-way valve has a flow path diameter substantially the same as the flow path diameter of the capillary tube. The three-way valve had a flow channel diameter substantially the same as the capillary flow channel diameter.
The refrigerator-freezer of Claim 3 characterized by the above-mentioned. The expansion device according to claim 1, claim 2 or claim 4 freezer refrigerator, wherein a from the center of the thickness direction of the refrigerator body wall is installed in the range of the outer half. It has a storage room for refrigerated or frozen food,
The said three-way valve was installed in the said storage chamber. The refrigerator-freezer in any one of Claims 1-6 characterized by the above-mentioned. The refrigerator-freezer according to any one of claims 1 to 7 , wherein the defrosting operation is performed in a state where the three-way valve is switched so that refrigerant flows through the bypass circuit. The refrigerator according to any one of claims 1 to 8, wherein the expansion device has a capacity coefficient larger than that of the capillary tube.

Images