JP2011247476A - Refrigerating cycle with refrigerant pipe for defrosting operation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating cycle capable of performing defrosting operation without taking a heat quantity from others and reliably performing a liquid back operation at this point.SOLUTION: In the refrigerating cycle (1) comprising a compressor (2), a condenser (5), an expansion valve (15), an evaporator (4) and the like, an accumulator (11) is provided on the upstream side of the compressor (2) and a direction switching mechanism (9) is provided on the downstream side. A receiver (14) is provided between the condenser (5) and the expansion valve (15) and the receiver (14) and the accumulator (11) are connected by a refrigerant pipe (R13) for defrosting having an opening and closing valve (29) interposed. A bypass pipe (R9) having a check valve (16) interposed is connected to the expansion valve (15) in parallel. During defrosting operation, a refrigerant is circulated from the compressor (2), to the evaporator(4), the bypass pipe (R9), the receiver (14), the refrigerant pipe (R13) for defrosting and the accumulator (11) in this order.

Description

  The present invention relates to a refrigeration cycle such as a heat pump, a refrigerator, and an air conditioner. More specifically, the present invention relates to a refrigeration cycle including a refrigerant tube for defrost operation that removes frost adhering to a heat exchanger.

  As is well known in the art, a refrigeration cycle such as a heat pump includes a compressor, first and second heat exchangers, an expansion valve, and the like, which are connected to each other by a refrigerant pipe. When the compressor is started and the refrigerant is circulated between the first heat exchanger, the expansion valve, the second heat exchanger, and the like, the state of the refrigerant changes to liquid and gas. At this time, the first heat exchanger functions as a condenser and the second heat exchanger functions as an evaporator, heat is released to the outside in the first heat exchanger, and heat is externally applied in the second heat exchanger. Is absorbed. Therefore, the first heat exchanger can be used as a heating source, the second heat exchanger can be used as a cooling source, and the air conditioning apparatus, the hot water supply apparatus, the refrigerator, and the like can be used.

  If the operation of the refrigeration cycle is continued, frost adheres to the second heat exchanger serving as a cooling source, and the efficiency of heat exchange decreases. Therefore, it is necessary to periodically perform a so-called defrost operation in which the second heat exchanger is defrosted. The method of defrost operation is also well-known, the direction which flows a refrigerant | coolant is changed, the 2nd heat exchanger which was acting as an evaporator is made to act as a condenser, and the 1st heat exchanger which was acting as a condenser To act as an evaporator. Specifically, the refrigerant line is switched by a four-way valve or the like, and the refrigerant compressed by the compressor is sent in the order of the second heat exchanger, the expansion valve, and the first heat exchanger. Then, the high-temperature and high-pressure refrigerant is condensed in the second heat exchanger, is reduced to a low pressure in the expansion valve, is vaporized in the first heat exchanger, and returns to the compressor. Therefore, since heat is released in the second heat exchanger, the attached frost can be melted. On the other hand, the first heat exchanger absorbs necessary heat from the outside.

JP 2008-224088 A

  Patent Document 1 describes a water heater that has a predetermined bypass path and can bypass a part of the refrigerant without passing through a heat exchanger and return it to the compressor during defrost operation. The water heater described in Patent Document 1 includes a compressor, an air heat exchanger, an expansion valve, a water heat exchanger, a bypass pipe, and the like. In normal operation, the refrigerant sent from the compressor circulates through the water heat exchanger, the expansion valve, and the air heat exchanger. Therefore, heat can be absorbed from outside air in the air heat exchanger, and water can be heated to supply hot water in the water heat exchanger. As described above, frost adheres to the air heat exchanger. During the defrost operation for removing the frost, the refrigerant sent from the compressor is sent in the order of the air heat exchanger, the expansion valve, and the water heat exchanger, but a part of the refrigerant is compressed from the upstream line of the expansion valve. Bypassed by a bypass pipe connected to the suction side of the machine. As a result, a part of the refrigerant returns directly to the compressor without passing through the water heat exchanger, and joins with another refrigerant returned through the water heat exchanger.

  The frost adhering to the heat exchanger can also be removed by a conventionally known defrost operation. However, there are problems to be solved. Specifically, when defrosting one heat exchanger to which frost has adhered, there is a problem in that the amount of heat required for defrosting must be absorbed from the outside in the other heat exchanger. That is, the other heat exchanger operates as a heating source during normal operation, but must operate as a cooling source during defrost operation. Therefore, hot water heated for hot water supply or heated air is used as a heat source, and the amount of heat is taken away, so that the temperature of the hot water is temporarily lowered or the temperature of the heating is lowered to deteriorate the performance of the apparatus. It is also not energy efficient. Furthermore, since the amount of heat required for defrost must be absorbed by the other heat exchanger, there is a problem that it takes a long time to obtain a sufficient amount of heat, and it is sufficient when the temperature of the heat source is low. There is also a problem that it cannot be defrosted.

  In the water heater described in Patent Document 1, since a part of the refrigerant is bypassed without passing through the water heat exchanger during the defrost operation, the amount of heat absorbed by the water heat exchanger can be suppressed, and is somewhat negative. Driving can be suppressed. However, since the amount of heat is taken away from the heated hot water, it is inevitable that the temperature of the hot water decreases. In addition, since a part of the refrigerant is bypassed, it takes time to obtain the amount of heat necessary for defrosting. Furthermore, there is a danger of so-called liquid back operation in which the refrigerant is sent to the compressor as a liquid. In other words, the bypassed refrigerant does not pass through the water heat exchanger and is returned as a liquid, but when the amount of refrigerant returned through the water heat exchanger is small, a part of the combined refrigerant is It is likely to become a liquid. Then, there is a risk that the compressor will break down due to the liquid back operation.

  An object of the present invention is to provide a refrigeration cycle that solves the above-described problems. Specifically, when a defrost operation is performed in a refrigeration cycle, the object is heated from hot objects such as hot water and air that are heated during normal operation. Refrigeration that does not take away heat and therefore does not reduce these temperatures, requires minimal energy and requires less time for defrosting, reliably preventing liquid back operation The purpose is to provide a cycle.

  In order to achieve the above object, the present invention comprises a refrigeration cycle comprising a compressor, a second heat exchanger as a condenser, an expansion valve, a first heat exchanger as an evaporator, and the like. In order to circulate the refrigerant. An accumulator is provided on the upstream side of the compressor, and a switching valve for switching the direction of the refrigerant flow is provided on the downstream side. A receiver is interposed between the condenser and the expansion valve. The receiver is connected to the accumulator by a defrost refrigerant pipe interposing an opening / closing valve. Further, a bypass pipe having a check valve interposed therein is connected in parallel to the expansion valve. When the switching valve is operated to open the on-off valve, the refrigerant circulates in the order of the compressor, the first heat exchanger, the bypass pipe, the receiver, the defrost refrigerant pipe, and the accumulator, and the first heat exchanger is defrosted. The

Thus, in order to achieve the above-mentioned object, the invention according to claim 1 includes at least a compressor, a second heat exchanger, a first throttle mechanism including an expansion valve or a capillary tube, and a first heat. A refrigerating cycle in which the refrigerant is circulated by being connected in this order, and an accumulator for separating the gas and liquid of the refrigerant is disposed on the downstream side of the compressor. Are each provided with a direction switching mechanism for switching the flow direction of the refrigerant, a refrigerant buffer for storing refrigerant is provided between the second heat exchanger and the first throttle mechanism, and from the refrigerant buffer, A defrost refrigerant pipe with an open / close valve is connected to the accumulator, and a first bypass pipe with a check valve is connected in parallel to the first throttle mechanism. , The direction When the switching mechanism is operated and the on-off valve is opened, the refrigerant circulates in the order of the compressor, the first heat exchanger, the first bypass pipe, the refrigerant buffer, the defrost refrigerant pipe, and the accumulator. Is configured to do.
According to a second aspect of the present invention, in the refrigeration cycle of the first aspect, the first heat exchanger is an air heat exchanger that exchanges heat with external air, and the second heat exchanger The heat exchanger is a cold / hot water heat exchanger that exchanges heat with cold / hot water used for air conditioning, and an expansion valve or a capillary tube is provided between the second heat exchanger and the refrigerant buffer. And a second bypass pipe interposing a check valve are provided in parallel, and the refrigeration cycle is also provided with a third heat exchanger that is a heat exchanger for hot water supply. The third heat exchanger is connected to a pipe branched from the direction switching mechanism and connected to the refrigerant buffer. When the heating operation position is selected by operating the direction switching mechanism, the refrigerant is , Compressor, second heat exchanger, second vibrator When the cooling operation position is selected by circulating in the order of the pipe, the refrigerant buffer, the first throttle mechanism, and the first heat exchanger, the refrigerant becomes the compressor, the first heat exchanger, and the first heat exchanger. When the bypass pipe, the refrigerant buffer, the second throttle mechanism, and the second heat exchanger are circulated in this order and the hot water supply operation position is selected, the refrigerant is the compressor, the third heat exchanger, and the refrigerant buffer. When the cooling hot water supply operation position is selected in the order of circulation of the first throttle mechanism and the first heat exchanger, the refrigerant is the compressor, the third heat exchanger, the refrigerant buffer, the second heat exchanger, and the second heat exchanger. The throttle mechanism is configured to circulate in the order of the second heat exchanger.
According to a third aspect of the present invention, in the refrigeration cycle according to the first or second aspect, the refrigerant buffer is constituted by a receiver.

  As described above, according to the present invention, at least the compressor, the second heat exchanger, the first throttle mechanism including the expansion valve or the capillary tube, and the first heat exchanger are provided. Since it is configured for a refrigeration cycle that is connected in order and circulates the refrigerant, the present invention can be applied to substantially most refrigeration cycles. According to the present invention, the refrigerant buffer for storing the refrigerant is provided between the second heat exchanger and the first throttle mechanism. Accordingly, in normal operation, the refrigerant is condensed in the second heat exchanger and then sent to the refrigerant buffer, and a predetermined amount of the refrigerant is stored in the refrigerant buffer in a relatively high temperature state. That is, sufficient heat energy is always secured in the refrigerant buffer, and this heat energy can be used during the defrost operation. According to the present invention, an accumulator for separating the gas and liquid of the refrigerant is provided on the upstream side of the compressor, and a direction switching mechanism for switching the direction of the flow of the refrigerant is provided on the downstream side. Is connected to the accumulator. In addition, a first bypass pipe having a check valve interposed therein is connected in parallel to the first throttle mechanism. In such a refrigeration cycle, when the direction switching mechanism is operated and the on-off valve is opened, the refrigerant is in the order of the compressor, the first heat exchanger, the first bypass pipe, the refrigerant buffer, the defrost refrigerant pipe, and the accumulator. It is configured to circulate. Therefore, the defrosting operation can be performed efficiently. That is, when such an operation is performed, the refrigerant that has condensed and released heat in the first heat exchanger becomes relatively low temperature and is sent to the refrigerant buffer. A relatively high temperature refrigerant is stored. Since this high-temperature refrigerant is sent to the accumulator via the defrost refrigerant pipe, the refrigerant is easily vaporized in the accumulator. This refrigerant can be sent to the first heat exchanger again by the compressor and defrosted. That is, it can defrost efficiently. In this circulation, in order to vaporize the refrigerant, it is not necessary to absorb heat from the outside in a special heat exchanger. If it does so, it is not necessary to take heat quantity from the original heating object, such as hot water and air, and these temperatures do not fall. That is, the performance of the refrigeration cycle does not deteriorate during the defrost operation. In the present invention, since the heat energy substantially accumulated in the refrigerant buffer is used in this way, an effect that defrosting can be performed in a short time is also obtained. Furthermore, since the refrigerant is surely gas-liquid separated by the accumulator provided on the upstream side of the compressor, the risk of so-called liquid back operation is also prevented. In the present invention, when the defrost operation is performed, the temperature of the refrigerant in the refrigeration buffer slightly decreases. If it does so, when returning to normal driving | operation, the effect that the supercooling of a refrigerant | coolant can be taken further will also be acquired.

It is a refrigerant piping flow figure showing typically the refrigerating cycle concerning a 1st embodiment of the present invention. It is a refrigerant | coolant piping flowchart which shows typically the refrigerating cycle which concerns on the 2nd Embodiment of this invention.

The present invention relates to a refrigeration cycle provided with a refrigerant pipe for defrost operation, and this refrigerant pipe is characterized. Hereinafter, a first embodiment of the present invention will be described.
The refrigeration cycle 1 according to the first embodiment has a configuration unique to the present invention as will be described in detail later, but is a heat pump that can be operated by appropriately switching between air conditioning and hot water supply, The flow of the refrigerant piping is shown in FIG. In other words, the refrigeration cycle 1 includes a compressor 2 that compresses a refrigerant and first to third heat exchangers 4, 5, 6, and the like that function as a condenser or an evaporator as is well known in the art. They are connected to each other by pipes and constitute a closed cycle. In brief, the first heat exchanger 4 is provided outdoors, and the second heat exchanger 5 is similarly evaporated so that it acts as an evaporator or condenser to exchange heat with external air. The third heat exchanger is configured to act as a condenser and heat hot water for hot water supply so that it acts as a condenser or a condenser to cool or heat cold / warm water for heating and cooling. . Hereinafter, the first to third heat exchangers 4, 5, and 6 are appropriately referred to as an air heat exchanger 4, a cold / hot water heat exchanger 5, and a hot water supply heat exchanger 6, respectively.

This will be described in detail below.
A refrigerant discharge pipe R1 exits from the compressor 2, and a three-way valve 8 having a conventionally known form is connected to the refrigerant discharge pipe R1. One branch from the three-way valve 8, that is, the hot water supply heat exchanger pipe R <b> 2 is connected to the refrigerant port of the hot water supply heat exchanger 6. The branch refrigerant pipe R3, which is the other branch, is connected to one port of the conventionally known four-way valve 9. The other three ports of the four-way valve 9 are connected to an air heat exchanger pipe R4, a cold / hot water heat exchanger pipe R5, and a refrigerant return pipe R6. The air heat exchanger 4 and the cold / hot water heat exchanger, respectively. 6, connected to the accumulator 11. As is well known, the accumulator 11 is a device that separates the gas and liquid of the refrigerant. The accumulator 11 has an outlet port connected to the compressor 2 by a refrigerant suction pipe R7, and protects the compressor 2 from sucking liquid refrigerant. Yes. When the three-way valve 8 and the four-way valve 9 are switched, the refrigerant discharged from the compressor 2 can be selectively sent to the air heat exchanger 4, the cold / hot water heat exchanger 5, and the hot water supply heat exchanger 6, respectively. Therefore, the three-way valve 8 and the four-way valve 9 can be said to be a direction switching mechanism that switches the direction of the refrigerant flow.

  The air heat exchanger 4 is installed outdoors and is provided with a fan 13 to efficiently exchange heat with the outside air, and is used as an evaporator when performing a heating operation or a hot water supply operation, and condensing when performing a cooling operation. Acts as a vessel. The air heat exchanger 4 is connected to a receiver 14 described later by a first receiver-side refrigerant pipe R8. A first expansion pipe 15 is interposed in the first receiver-side refrigerant pipe R8, and a first bypass pipe R9 in which a first check valve 16 is interposed in parallel with the first expansion valve 15 is provided. Is connected. Accordingly, the refrigerant flows through the first check valve 16 and the first bypass pipe R9 when flowing in the direction from the air heat exchanger 4 to the receiver 14, and flows through the first expansion valve 15 when flowing in the reverse direction. . The first receiver-side refrigerant pipe R8 is bifurcated on the receiver 14 side, and one branch is connected to the receiver 14 via a first receiver-side check valve 18. The first receiver-side check valve 18 allows the refrigerant to flow from the air heat exchanger 4 to the receiver 14 side but not in the reverse direction. The other branch of the first receiver side refrigerant pipe R8 is connected to the receiver 14 via the first on-off valve 19, and when the valve is opened, the refrigerant is sent from the receiver 14 to the air heat exchanger 4. Yes.

  The cold / hot water heat exchanger 5 is a heat exchanger in which heat is exchanged between the cold / hot water circulating in the room for cooling and heating and the refrigerant, and is configured by a conventionally known plate heat exchanger. When the cold / hot water heat exchanger 5 acts as a condenser, the cold / hot water can be heated to heat the room, and when it acts as an evaporator, the cold / hot water can be cooled to cool the room. The cold / hot water exchanger 5 is also connected to the receiver 14 by the second receiver-side refrigerant pipe R10. Similarly to the first receiver-side refrigerant pipe R8, the second receiver-side refrigerant pipe R10 is also provided with a second expansion valve 21, and in parallel with the second expansion valve 21, a second check valve is provided. A second bypass pipe R11 in which the valve 22 is interposed is connected. Accordingly, the refrigerant flows through the second check valve 22 and the second bypass pipe R11 when flowing in the direction from the cold / hot water heat exchanger 5 to the receiver 14, and flows through the second expansion valve 21 when flowing in the reverse direction. Become. The second receiver-side refrigerant pipe R <b> 10 is also bifurcated on the receiver 14 side, and one branch is connected to the receiver 14 via the second receiver-side check valve 23. The second receiver-side check valve 23 also causes the refrigerant to flow from the cold / hot water heat exchanger 5 to the receiver 14 side but not in the reverse direction. The other branch of the second receiver side refrigerant pipe R10 is connected to the receiver 14 via the second on-off valve 24, and when the valve is opened, the refrigerant is sent from the receiver 14 to the cold / hot water heat exchanger 5. ing.

  The hot water supply heat exchanger 6 is a plate-type heat exchanger that acts as a condenser, and can supply hot water by heating tap water to a relatively high temperature. The hot water supply heat exchanger 6 is also connected to the receiver 14 by a third receiver side refrigerant pipe R12. A third receiver-side check valve 25 is interposed in the third receiver-side refrigerant pipe R <b> 12 so that the refrigerant does not flow backward from the receiver 14. In the present embodiment, a capillary tube 27 and a bypass on-off valve 28 are connected in parallel to the third receiver-side refrigerant pipe R12. The refrigerant condensed in the hot water supply heat exchanger 6 can be sent to the receiver 14 through the bypass on-off valve 28, or can be sent to the receiver 14 after being decompressed by the capillary tube 27 when the valve is closed. By reducing the pressure of the refrigerant with the capillary tube 27, the refrigerant can be largely supercooled without applying a load to the compressor 2, and high-temperature hot water can be obtained.

  The receiver 14 is a refrigerant buffer that is made of a container having a predetermined capacity and stores the refrigerant. For example, about 3.5 liters of the refrigerant is stored as a liquid. During the cooling / heating operation or the hot water supply operation, the refrigerant stored in the receiver 14 is at a relatively high temperature, for example, 50 to 55 ° C. In the present invention, the defrosting is performed by using the heat energy of the refrigerant stored at a relatively high temperature and in a sufficient amount.

  The refrigeration cycle 1 is provided with a refrigerant pipe peculiar to the present invention, that is, a defrost refrigerant pipe R13. The defrost refrigerant pipe R <b> 13 is a pipe through which a refrigerant flows during defrost operation, and connects the receiver 14 and the accumulator 11. A defrost refrigerant pipe opening / closing valve 29 is interposed in the defrost refrigerant pipe R13.

  The operation of the refrigeration cycle 1 according to the present embodiment will be described. Although not shown in FIG. 1, the refrigeration cycle 1 is also provided with a controller, and various valves and devices are automatically driven by commands from the controller. However, in the following description, it will be described as being operated manually. The refrigeration cycle 1 according to the present embodiment is characterized by a defrost operation that will be described later. First, a normal operation will be described.

(A) Heating operation The three-way valve 8 and the four-way valve 9 are switched to allow the refrigerant discharge pipe R1, the branch refrigerant pipe R3, and the cold / hot water heat exchanger pipe R5 of the compressor 2 to communicate with each other. When the four-way valve 9 is switched in this way, the air heat exchanger pipe R4 and the refrigerant return pipe R6 communicate with each other. The first on-off valve 19 is opened, and the second on-off valve 24 and the defrost refrigerant pipe on-off valve 29 are closed. When the compressor 2 is driven, the refrigerant discharged from the compressor 2 is the cold / hot water heat exchanger 5, the second bypass pipe R11, the receiver 14, the first receiver side refrigerant pipe R8, the first expansion valve 15, The air heat exchanger 4 and the accumulator 11 flow in this order and circulate in the compressor 2. Therefore, the refrigerant condenses in the cold / hot water heat exchanger 5 to release heat to heat the cold / hot water, evaporates in the air heat exchanger 4 and absorbs heat from the outside air. Heating can be performed with heated cold / hot water.

(B) Cooling operation The three-way valve 8 and the four-way valve 9 are switched to allow the refrigerant discharge pipe R1, the branch refrigerant pipe R3, and the air heat exchanger pipe R4 of the compressor 2 to communicate with each other. When the four-way valve 9 is switched in this way, the cold / hot water heat exchanger pipe R5 and the refrigerant return pipe R6 communicate with each other as shown in FIG. The second on-off valve 24 is opened, and the first on-off valve 19 and the defrost refrigerant pipe on-off valve 29 are closed. When the compressor 2 is driven, the refrigerant discharged from the compressor 2 is the air heat exchanger 4, the first bypass pipe R9, the receiver 14, the second receiver side refrigerant pipe R10, the second expansion valve 21, the cold temperature. The water heat exchanger 5 and the accumulator 11 flow in this order and circulate in the compressor 2. Accordingly, the refrigerant condenses in the air heat exchanger 4 to release heat to the outside air, and evaporates in the cold / hot water heat exchanger 5 to cool the cold / hot water. It can be cooled with cooled cold / hot water.

(C) Hot water supply operation The three-way valve 8 is switched to allow the refrigerant discharge pipe R1 of the compressor 2 and the hot water supply heat exchanger pipe R2 to communicate with each other. Further, the four-way valve 9 is switched to allow the air heat exchanger pipe R4 and the refrigerant return pipe R6 to communicate with each other. The first on-off valve 19 is opened, and the second on-off valve 24 and the defrost refrigerant pipe on-off valve 29 are closed. When the compressor 2 is driven, the refrigerant discharged from the compressor 2 is the hot water supply heat exchanger 6, the third receiver side refrigerant pipe R12, the receiver 14, the first receiver side refrigerant pipe R8, and the first expansion valve 15. The air heat exchanger 4 and the accumulator 11 flow in this order and circulate in the compressor 2. Therefore, the refrigerant condenses in the hot water supply heat exchanger 6 to release heat to heat the tap water, evaporates in the air heat exchanger 4 and absorbs heat from the outside air. Therefore, hot water can be supplied.

(D) Cooling and hot water supply operation The three-way valve 8 is switched to communicate the refrigerant discharge pipe R1 of the compressor 2 with the hot water supply heat exchanger pipe R2. In addition, the four-way valve 9 is switched to allow the cold / hot water heat exchanger pipe R5 and the refrigerant return pipe R6 to communicate with each other. The second on-off valve 24 is opened, and the first on-off valve 19 and the defrost refrigerant pipe on-off valve 29 are closed. When the compressor 2 is driven, the refrigerant discharged from the compressor 2 is the hot water supply heat exchanger 6, the third receiver side refrigerant pipe R12, the receiver 14, the second receiver side refrigerant pipe R10, and the second expansion valve 21. The cold / hot water heat exchanger 5 and the accumulator 11 flow in this order, and circulate in the compressor 2. Accordingly, the refrigerant condenses in the hot water supply heat exchanger 6 to release heat to heat the tap water, and evaporates in the cold / hot water heat exchanger 5 to cool the cold / hot water. It can supply hot water and can be cooled by cooled cold / hot water.

(E) Defrost operation If heating operation and hot water supply operation are continued for a predetermined time, frost adheres to the air heat exchanger 4 and the efficiency of heat exchange decreases. Therefore, it is necessary to carry out so-called defrost that periodically removes frost adhering to the air heat exchanger 4. The defrost operation is performed as follows. By switching between the three-way valve 8 and the four-way valve 9, the refrigerant discharge pipe R1, the branch refrigerant pipe R3, and the air heat exchanger pipe R4 of the compressor 2 are communicated. The first on-off valve 19 and the second on-off valve 24 are closed. Open the defrost refrigerant pipe on-off valve 29. When the compressor 2 is driven, the refrigerant discharged from the compressor 2 flows in the order of the air heat exchanger 4, the first bypass pipe R 9, the receiver 14, the defrost refrigerant pipe R 13, and the accumulator 11, and circulates to the compressor 2. . In this circulation, the refrigerant changes as follows. First, the frost that has condensed and adhered in the air heat exchanger 4 is melted. The liquefied refrigerant becomes low temperature and is delayed by the receiver 14. Since a sufficient amount of the relatively high temperature refrigerant is stored in the receiver 14, the high temperature refrigerant flows to the accumulator 11 via the defrost refrigerant pipe R13. Since the refrigerant is hot, it is easily vaporized by an accumulator. The vaporized refrigerant is discharged again by the compressor 2. Thereafter, the air heat exchanger 4 is defrosted in the same manner. In the present embodiment, it is not necessary to use a special heat exchanger to evaporate the refrigerant during the defrost operation. Therefore, it is not necessary to absorb heat from the outside in other heat exchangers, for example, the second and third heat exchangers 5 and 6, and the efficiency of the refrigeration cycle 1 is not reduced. In addition, although the liquid refrigerant is returned to the accumulator 11, the refrigerant is reliably gas-liquid separated in the accumulator 11, so there is no risk that the liquid refrigerant returns to the compressor 2.

  FIG. 2 shows the refrigerant flow of the refrigeration cycle 1 ′ according to the second embodiment. The same devices, refrigerant pipes, etc. as in the previous embodiment are given the same reference numerals and will not be described in detail. In the refrigeration cycle 1 'according to the second embodiment, the heat exchanger is generally composed of first and second heat exchangers 4, 5, that is, an air heat exchanger 4 and a cold / hot water heat exchanger 5. It is configured as a heat pump. As can be easily understood by those skilled in the art, the heating operation and the cooling operation can be switched by the refrigeration cycle 1 '. Also in the refrigeration cycle 1 ′ according to the second embodiment, during the defrost operation, the refrigerant is the compressor 2, the air heat exchanger 4, the first bypass pipe R9, the receiver 14, the defrost refrigerant pipe R13, the accumulator 11, The compressor 2 is circulated in this order. Then, as in the previous embodiment, there is no need to absorb heat in the cold / hot water heat exchanger 5 and defrosting can be performed efficiently.

  Various modifications can be made to the present embodiment. For example, the receiver 14 only needs to store a predetermined amount of refrigerant. Therefore, the receiver 14 may be configured as a simple container, or a part of the refrigerant pipe may be thickened so that a predetermined amount of refrigerant is retained. Further, in this embodiment, an expansion valve is provided as a throttling mechanism for reducing the pressure of the refrigerant, but these can be replaced with a capillary tube. The present invention can be applied not only to a heat pump used for air conditioning and hot water supply, but also to a refrigerator or other refrigeration cycle.

DESCRIPTION OF SYMBOLS 1 Refrigeration cycle 2 Compressor 4 1st heat exchanger Air heat exchanger 5 2nd heat exchanger Cold / hot water heat exchanger 6 3rd heat exchanger Hot water supply heat exchanger 9 Four-way valve 11 Accumulator 14 Receiver 15 1st Expansion valve 16 first check valve 18 first receiver side check valve 19 first on-off valve 21 second expansion valve 22 second check valve 23 second receiver side check valve 24 second Open / close valve 25 third receiver side check valve 27 capillary tube 28 bypass open / close valve 29 defrost refrigerant pipe open / close valve R1 refrigerant discharge pipe R2 hot water heat exchanger pipe R3 branch refrigerant pipe R4 air heat exchanger pipe R5 Heat exchanger pipe R6 Refrigerant return pipe R7 Refrigerant suction pipe R8 First receiver side refrigerant pipe R9 First bypass pipe R10 Second receiver side refrigerant pipe R11 Second bypass pipe R12 Third receiver side refrigerant Refrigerant pipe for R13 defrost

Claims (3)

At least a compressor, a second heat exchanger, a first throttle mechanism composed of an expansion valve or a capillary tube, and a first heat exchanger are provided, and these are connected in this order to circulate the refrigerant. A refrigeration cycle
An accumulator for separating the gas and liquid of the refrigerant is provided on the upstream side of the compressor, and a direction switching mechanism for switching the flow direction of the refrigerant is provided on the downstream side.
A refrigerant buffer for storing refrigerant is provided between the second heat exchanger and the first throttling mechanism, and a defrost refrigerant pipe having an open / close valve is provided from the refrigerant buffer to the accumulator. Connected,
The first throttle mechanism is connected in parallel with a first bypass pipe having a check valve interposed therein,
When the direction switching mechanism is operated and the on-off valve is opened, the refrigerant includes the compressor, the first heat exchanger, the first bypass pipe, the refrigerant buffer, the defrost refrigerant pipe, and the accumulator. A refrigeration cycle characterized by being circulated in order. The refrigeration cycle according to claim 1, wherein the first heat exchanger is an air heat exchanger that exchanges heat with external air.
The second heat exchanger is a cold / hot water heat exchanger for exchanging heat with cold / hot water used for air conditioning.
Between the second heat exchanger and the refrigerant buffer, a second throttle mechanism composed of an expansion valve or a capillary tube and a second bypass pipe interposing a check valve are provided in parallel,
The refrigeration cycle is also provided with a third heat exchanger, which is a heat exchanger for hot water supply, and the third heat exchanger is connected to a pipe branched from the direction switching mechanism and connected to the refrigerant buffer. Connected,
When the direction switching mechanism is operated to select the heating operation position, the refrigerant is a compressor, the second heat exchanger, the second bypass pipe, the refrigerant buffer, the first throttle mechanism, the first Circulate in the order of heat exchangers,
When the cooling operation position is selected, the refrigerant circulates in the order of the compressor, the first heat exchanger, the first bypass pipe, the refrigerant buffer, the second throttle mechanism, and the second heat exchanger. ,
When the hot water supply operation position is selected, the refrigerant circulates in the order of the compressor, the third heat exchanger, the refrigerant buffer, the first throttle mechanism, and the first heat exchanger.
When the cooling hot water supply operation position is selected, the refrigerant circulates in the order of the compressor, the third heat exchanger, the refrigerant buffer, the second throttle mechanism, and the second heat exchanger. A refrigeration cycle characterized by 3. The refrigeration cycle according to claim 1, wherein the refrigerant buffer includes a receiver.

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